JP2009156195A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine capable of suppressing the shortening of a life. <P>SOLUTION: This internal combustion engine is provided with a secondary air supply means 70 capable of supplying secondary air to an exhaust passage 46 to discharge exhaust gas from a combustion chamber 18, an intake air quantity detection means to detect an intake air quantity of air to take in the combustion chamber 18, an atmospheric air pressure detection means 62 to detect atmospheric air pressure, a setting means 82 to set a determination value with respect to the intake air quantity according to atmospheric air pressure and a secondary air control means 81 to control the work of the secondary air supply means 70 according to the intake air quantity and the determination value. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an internal combustion engine, and more particularly to an internal combustion engine that supplies secondary air to an exhaust passage.

  Generally, in an internal combustion engine, there is a catalytic converter including a three-way catalyst that oxidizes and reduces harmful substances such as unburned hydrocarbon (HC), carbon monoxide (CO), and nitrogen oxide (NOx) in exhaust gas. It is provided on the exhaust passage. This catalytic converter is activated when it reaches a predetermined activation temperature or higher, and sufficient purification efficiency of harmful substances can be obtained in the vicinity of the theoretical air-fuel ratio.

  Here, when the internal combustion engine is cold-started at a low temperature, since the intake air temperature is generally low and the atomization of the fuel spray is not sufficient, the amount of fuel supplied into the combustion chamber through the fuel injection valve is increased. It is common to stabilize combustion and promote warm-up. However, if the fuel injection amount is increased to enrich the mixture, unburned fuel (HC, CO, etc.) in the exhaust gas also increases. In addition, the temperature of the catalyst is low when cold and is not fully activated. Therefore, when the air-fuel mixture is enriched when the catalyst temperature does not reach the activation temperature, such as during cold start, secondary air supply (AI) control is performed to Secondary air is mixed into the exhaust gas immediately after being discharged, for example, exhaust gas in the exhaust manifold, and an oxidation reaction that recombusts unburned fuel components contained in the exhaust gas, so-called afterburning, is promoted. In this way, purification of unburned fuel components is promoted upstream of the catalytic converter, and activation of the catalyst is accelerated by the reaction heat.

  As such a conventional internal combustion engine, for example, the secondary air supply control device for an internal combustion engine described in Patent Document 1 has an air flow as a temperature equivalent amount in a three-way catalyst at the start of the internal combustion engine and immediately before the stop of the internal combustion engine. The secondary air introduction mechanism (secondary air supply device) is controlled based on the initial value of the integrated intake air amount calculated from the integrated intake air amount (integrated value of the intake air amount) by the meter and the stop time of the internal combustion engine. The secondary air is supplied to the three-way catalyst from the upstream side of the exhaust passage by driving the air pump that pumps the air. Thus, when the internal air engine is started, when the secondary air is supplied to the three-way catalyst in the exhaust passage, the transition state of the integrated intake air amount that is extremely equal to the transition state of the catalyst temperature of the actual three-way catalyst is used. Without detecting the actual catalyst temperature, the secondary air is supplied to the three-way catalyst with sufficient accuracy without excess or deficiency, and the three-way catalyst is activated early.

JP 2004-76591 A

  However, in the secondary air supply control device for an internal combustion engine described in Patent Document 1 described above, for example, to control the operation and stop of the secondary air supply device with respect to the intake air amount sucked into the internal combustion engine. When the air pump of the secondary air supply device is operated and stopped according to the determination value, for example, the altitude at which the vehicle on which the internal combustion engine is mounted fluctuates, so that the secondary air supply device There is a possibility that the operation period of the system becomes longer, or unnecessary operation and stop are repeated. Thereby, for example, there is a possibility that deterioration of an air pump or the like of the secondary air supply device is likely to proceed, and as a result, the life of the internal combustion engine provided with the secondary air supply device may be reduced.

  Then, an object of this invention is to provide the internal combustion engine which can suppress the fall of a lifetime.

  In order to achieve the above object, an internal combustion engine according to a first aspect of the present invention is provided with a secondary air supply means capable of supplying secondary air to an exhaust passage for discharging exhaust gas from a combustion chamber, and suctioned into the combustion chamber. An intake air amount detecting means for detecting an intake air amount of air, an atmospheric pressure detecting means for detecting atmospheric pressure, a setting means for setting a determination value for the intake air amount based on the atmospheric pressure, and the intake air Secondary air control means for controlling the operation of the secondary air supply means based on the quantity and the determination value.

  In the internal combustion engine according to the second aspect of the invention, the setting means sets an integrated intake air amount determination value that is a determination value for the integrated intake air amount that is an integrated value of the intake air amount, according to an operating state. Air amount determination value setting means; and integrated intake air amount determination value correction means for correcting the integrated intake air amount determination value based on the atmospheric pressure, wherein the integrated intake air amount determination value correction means The integrated intake air amount determination value at a low atmospheric pressure side is corrected to a value smaller than the integrated intake air amount determination value at a high atmospheric pressure side, and the secondary air control means corrects the integrated intake air amount to the correction value. The secondary air supply means is controlled to be in an operating state when it is smaller than the subsequent integrated intake air amount determination value, while before the integrated intake air amount determination value is larger than the corrected integrated intake air amount determination value. And controlling the secondary air supply means to the stop state.

  In the internal combustion engine according to the third aspect of the invention, the setting means sets the instantaneous intake air amount determination value, which is a determination value for the instantaneous intake air amount that is the instantaneous intake air amount, according to the operating state. An amount determination value setting means; and an instantaneous intake air amount determination value correction means for correcting the instantaneous intake air amount determination value based on the atmospheric pressure, wherein the instantaneous intake air amount determination value correction means includes the atmospheric pressure Corrects the instantaneous intake air amount determination value on the high atmospheric pressure side to a value larger than the instantaneous intake air amount determination value on the low atmospheric pressure side, and the secondary air control means adjusts the instantaneous intake air amount after the correction. The secondary air supply means is controlled to be stopped when the instantaneous intake air amount determination value is larger than the value.

  According to the internal combustion engine of the present invention, a setting unit that sets a determination value for the intake air amount based on the atmospheric pressure, and a secondary that controls the operation of the secondary air supply unit based on the intake air amount and the determination value. Since the setting means sets the determination value based on the atmospheric pressure, it is possible to suppress unnecessary operation and stop of the secondary air supply means, and to suppress a decrease in life. Can do.

  Embodiments of an internal combustion engine according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  1 is a schematic configuration diagram of an engine according to an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a secondary air supply device for an engine according to the embodiment of the present invention, and FIG. 3 is an embodiment of the present invention. FIG. 4 is a flowchart for explaining secondary air supply control based on the integrated intake air amount of the engine according to the embodiment of the present invention. FIG. 5 is a flowchart for explaining secondary air supply control based on the instantaneous intake air amount of the engine according to the embodiment of the present invention. FIG. 6 is based on the instantaneous intake air amount of the engine according to the embodiment of the present invention. It is a diagram explaining the secondary air supply control.

  As shown in FIGS. 1 and 2, an engine 10 as an internal combustion engine according to the present embodiment is mounted on a vehicle such as a passenger car or a truck, and a multi-cylinder in which fuel spray is directly injected into a combustion chamber 18 by an injector 41 described later. This is an in-cylinder injection type engine, and performs a series of four strokes consisting of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke while a piston 14 provided in a cylinder bore 13 so as to be capable of reciprocating is reciprocated twice. It is a cycle engine.

  The engine 10 of the present embodiment is a so-called multi-cylinder in-cylinder injection type, in which a cylinder head 12 is fastened on a cylinder block 11, and pistons 14 are attached to a plurality of cylinder bores 13 formed in the cylinder block 11. Each is fitted so that it can move up and down. A crankcase 15 is fastened to the lower part of the cylinder block 11, and a crankshaft 16 is rotatably supported in the crankcase 15. Each piston 14 is connected to the crankshaft 16 via a connecting rod 17. Has been. Note that oil supplied to each part of the engine 10 is stored at the bottom of the crankcase 15.

  The combustion chamber 18 is constituted by the wall surface of the cylinder bore 13 in the cylinder block 11, the lower surface 11 a (see FIG. 2) of the cylinder head 12, and the top surface of the piston 14. 11a) has a pent roof shape that is inclined so that the central portion is higher. In the combustion chamber 18, a mixture of fuel and air can be combusted, and an intake port 19 and an exhaust port 20 are formed facing the upper portion of the combustion chamber 18, that is, the lower surface 11 a of the cylinder head 12, The lower ends of the intake valve 21 and the exhaust valve 22 are located with respect to the intake port 19 and the exhaust port 20, respectively. The intake valve 21 and the exhaust valve 22 are supported by the cylinder head 12 so as to be movable in the axial direction, and are urged and supported in a direction (upward in FIG. 1) for closing the intake port 19 and the exhaust port 20. ing. An intake camshaft 23 and an exhaust camshaft 24 are rotatably supported on the cylinder head 12, and the intake cam 25 and the exhaust cam 26 are in contact with upper ends of the intake valve 21 and the exhaust valve 22.

  Although not shown, the crankshaft sprocket fixed to the crankshaft 16 and the camshaft sprockets respectively fixed to the intake camshaft 23 and the exhaust camshaft 24 are wound with endless timing chains. The crankshaft 16, the intake camshaft 23, and the exhaust camshaft 24 can be interlocked.

  Accordingly, when the intake camshaft 23 and the exhaust camshaft 24 rotate in synchronization with the crankshaft 16, the intake cam 25 and the exhaust cam 26 move up and down the intake valve 21 and the exhaust valve 22 at a predetermined timing. 19 and the exhaust port 20 can be opened and closed so that the intake port 19 and the combustion chamber 18 can communicate with the combustion chamber 18 and the exhaust port 20, respectively. In this case, the intake camshaft 23 and the exhaust camshaft 24 are set to rotate once (360 degrees) while the crankshaft 16 rotates twice (720 degrees). Therefore, the engine 10 executes the four strokes of the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke while the crankshaft 16 rotates twice. At this time, the intake camshaft 23 and the exhaust camshaft 24 are set to one. It will rotate.

  Further, the valve mechanism of the engine 10 is a variable valve timing-intelligent (VVT) mechanism 27 or 28 that controls the intake valve 21 and the exhaust valve 22 at an optimal opening / closing timing according to the operating state. It has become. The intake / exhaust variable valve mechanisms 27 and 28 are configured by providing VVT controllers 29 and 30 at the shaft end portions of the intake camshaft 23 and the exhaust camshaft 24, and the oil pressure from the oil control valves 31 and 32 is supplied to the intake camshaft 23 and the exhaust camshaft 24. The phases of the camshafts 23 and 24 with respect to the cam sprockets are changed by acting on advance and retard chambers (not shown) of the VVT controllers 29 and 30, and the opening and closing timings of the intake valve 21 and the exhaust valve 22 are advanced or retarded. Is something that can be done. In this case, the intake / exhaust variable valve operating mechanisms 27, 28 advance or retard the opening / closing timing while keeping the operating angle (opening period) of the intake valve 21 and the exhaust valve 22 constant. Further, the intake camshaft 23 and the exhaust camshaft 24 are provided with cam position sensors 33 and 34 for detecting their rotational phases.

  A surge tank 36 is connected to the intake port 19 via an intake manifold 35, and an intake pipe 37 is connected to the surge tank 36. An air cleaner 38 is attached to an air intake port of the intake pipe 37. . An electronic throttle device 40 having a throttle valve 39 is provided on the downstream side of the air cleaner 38. The cylinder head 12 is provided with an injector (fuel injection valve) 41 that directly injects fuel into the combustion chamber 18, and the injector 41 is located on the intake port 19 side and is inclined at a predetermined angle in the vertical direction. Are arranged. The injector 41 is provided such that a fuel injection port opens into the combustion chamber 18. An injector 41 attached to each cylinder is connected to a delivery pipe 42, and a high pressure fuel pump (fuel pump) 44 is connected to the delivery pipe 42 via a high pressure fuel supply pipe 43. Further, the cylinder head 12 is provided with a spark plug 45 that is located above the combustion chamber 18 and ignites the air-fuel mixture.

  On the other hand, an exhaust pipe 47 is connected to the exhaust port 20 via an exhaust manifold 46, and the exhaust pipe 47 is a purification catalyst that purifies harmful substances such as HC, CO, and NOx contained in the exhaust gas. The three-way catalysts 48 and 49 are mounted. Further, the engine 10 is provided with a starter motor 50 that performs cranking. When an unillustrated pinion gear meshes with the ring gear when the engine is started, the rotational force is transmitted from the pinion gear to the ring gear to rotate the crankshaft 16. Can do.

  By the way, the vehicle is equipped with an electronic control unit (ECU) 51 that is configured around a microcomputer and can control each part of the engine 10, and the ECU 51 can control the injector 41, the spark plug 45, and the like. Yes. That is, an airflow sensor 52 and an intake air temperature sensor 53 as intake air amount detection means are mounted on the upstream side of the intake pipe 37, and an intake pressure sensor 54 is provided in the surge tank 36, and the measured combustion chamber The intake air amount of intake air, intake air temperature, and intake pressure (intake pipe negative pressure) are output to the ECU 51. In addition, a throttle position sensor 55 is attached to the electronic throttle device 40, and the current throttle opening is output to the ECU 51. Here, the ECU 51 can calculate the engine load (load factor) as the internal combustion engine load based on the detected throttle opening and intake air amount. The accelerator position sensor 56 outputs the current accelerator opening to the ECU 51. Further, a crank angle sensor 57 that detects the crank angle of the engine 10 outputs the detected crank angle of each cylinder to the ECU 51, and the ECU 51 performs an intake stroke, a compression stroke, and an expansion stroke in each cylinder based on the detected crank angle. The exhaust stroke is determined, and the engine speed is calculated. Here, the engine speed corresponds to the rotational speed of the crankshaft 16 in other words. If the rotational speed of the crankshaft 16 increases, the rotational speed of the crankshaft 16, that is, the engine rotational speed of the engine 10 also increases. Get higher.

  The cylinder block 11 is provided with a water temperature sensor 58 that detects the engine cooling water temperature, and outputs the detected engine cooling water temperature to the ECU 51. The delivery pipe 42 communicating with each injector 41 is provided with a fuel pressure sensor 59 that detects the fuel pressure, and outputs the detected fuel pressure to the ECU 51. On the other hand, the exhaust pipe 47 is provided with an A / F sensor 60 that detects the air-fuel ratio of the engine 10 upstream of the three-way catalyst 48 in the exhaust gas flow direction, and an oxygen sensor 61 downstream of the exhaust gas flow direction. The A / F sensor 60 detects the exhaust gas air-fuel ratio of the exhaust gas before being introduced into the three-way catalyst 48, outputs the detected air-fuel ratio to the ECU 51, and the oxygen sensor 61 is discharged from the three-way catalyst 48. Thereafter, the oxygen concentration of the exhaust gas is detected, and the detected oxygen concentration is output to the ECU 51. The air-fuel ratio (estimated air-fuel ratio) detected by the A / F sensor 60 is used for feedback control of the air-fuel ratio (theoretical air-fuel ratio) of the mixed gas composed of intake air and fuel. That is, the A / F sensor 60 detects the exhaust air-fuel ratio from the rich range to the lean range from the oxygen concentration in the exhaust gas and the unburned gas concentration, and feeds this back to the ECU 51 to correct the fuel injection amount. Thus, the combustion can be controlled to an optimum combustion state that matches the operating state.

  Therefore, the ECU 51 drives the high-pressure fuel pump 44 based on the detected fuel pressure so that the fuel pressure becomes a predetermined pressure, and also detects the detected intake air amount, intake air temperature, intake pressure, throttle opening, accelerator opening. The fuel injection amount (fuel injection time), the injection timing, the ignition timing, etc. are determined based on the engine operating state such as the engine speed and the engine coolant temperature, and the injector 41 and the spark plug 45 are driven to perform the fuel injection and ignition. Execute. Further, the ECU 51 feeds back the detected oxygen concentration of the exhaust gas to correct the fuel injection amount so that the air-fuel ratio becomes stoichiometric (theoretical air-fuel ratio).

  The ECU 51 can control the intake / exhaust variable valve mechanisms 27 and 28 based on the engine operating state. That is, when the temperature is low, the engine is started, the engine is idle, or the load is light, the exhaust gas blows back into the intake port 19 or the combustion chamber 18 by eliminating the overlap between the exhaust valve 22 closing timing and the intake valve 21 opening timing. Reduce the amount to enable stable combustion and improved fuel efficiency. Further, at the time of medium load, by increasing the overlap, the internal EGR rate is increased to improve the exhaust gas purification efficiency, and the pumping loss is reduced to improve the fuel consumption. Further, at the time of high-load low-medium rotation, the closing timing of the intake valve 21 is advanced, thereby reducing the amount of intake air that blows back to the intake port 19 and improving the volume efficiency. At the time of high load and high rotation, the closing timing of the intake valve 21 is retarded in accordance with the rotation speed, so that the timing is adjusted to the inertial force of the intake air and the volume efficiency is improved.

  Here, for example, when the engine 10 of the present embodiment is cold-started under a low temperature condition, the intake air temperature is generally low and the atomization of the fuel spray is not sufficient, so the fuel spray is supplied into the combustion chamber 18 through the injector 41. Generally, the amount of fuel is increased to stabilize engine combustion and promote warm-up. However, if the fuel injection amount is increased to enrich the mixture, unburned fuel (HC, CO, etc.) in the exhaust gas also increases. In addition, the temperature of the three-way catalysts 48 and 49 is low when cold and is not fully activated. For this reason, when the air-fuel mixture is enriched when the catalyst temperature does not reach the activation temperature, such as during cold start, so-called secondary air supply (AI) control is performed and each combustion chamber is controlled. Exhaust gas immediately after being exhausted from the exhaust gas 18, that is, exhaust gas in the exhaust port 20 serving as an exhaust passage for exhausting the exhaust gas from the combustion chamber 18 and exhaust gas in the exhaust manifold 46, unburned fuel components contained in the exhaust gas It promotes the so-called after-burning oxidation reaction. In this way, purification of unburned fuel components is promoted upstream of the three-way catalyst 48, and activation of the catalyst is accelerated by the reaction heat.

  Specifically, the engine 10 can supply outside air as secondary air into the exhaust manifold 46 (between the combustion chamber 18 and the three-way catalyst 48) as an exhaust passage for discharging exhaust gas from the combustion chamber 18. A secondary air supply device 70 is provided as secondary air supply means. The secondary air supply device 70 includes a secondary air introduction passage 71, an air filter 72, an air pump 73 as a pneumatic feeding means, a combination valve 74 having an on-off valve 75 and a check valve 76, and an intake pressure introduction passage. 77, a switching valve 78, and a secondary air pressure sensor 79.

  The secondary air introduction passage 71 is for introducing secondary air in the exhaust manifold 46. One end of the secondary air introduction passage 71 is connected to the collecting passage portion where the exhaust branch passage portions of the exhaust manifold 46 gather on the upstream side of the A / F sensor 60 with respect to the flow direction (exhaust direction) of the exhaust gas. ing.

  The air filter 72 removes foreign matters in the outside air introduced into the secondary air introduction passage 71, and is disposed at the other end portion on the most upstream side of the secondary air introduction passage 71 with respect to the direction of introduction of the secondary air. Is provided.

  The air pump 73 pumps the secondary air (outside air) introduced into the exhaust manifold 46, and is provided downstream of the air filter 72 in the secondary air introduction passage 71 with respect to the direction of introduction of the secondary air. ing. The air pump 73 is a pump that operates using an electric motor as a drive source, and is electrically connected to the ECU 51, and the driving of the ECU 51 is controlled by the ECU 51.

  The combination valve 74 is provided on the downstream side of the air pump 73 in the secondary air introduction passage 71 with respect to the introduction direction of the secondary air. The combination valve 74 is configured by integrating a pressure-driven on-off valve 75 that opens and closes the secondary air introduction passage 71 and a check valve 76 on the downstream side thereof. The check valve 76 is a valve mechanism for allowing only a forward fluid flow from the air pump 73 to the exhaust manifold 46 and preventing a reverse flow.

  That is, the secondary air introduction passage 71 is provided with the air filter 72, the air pump 73, the opening / closing valve 75 of the combination valve 74, and the check valve 76 of the combination valve 74 in order from the upstream side with respect to the introduction direction of the secondary air. .

  One end of the intake pressure introduction passage 77 is connected to the on-off valve 75 of the combination valve 74, and the other end is connected to the intake manifold 35 as an intake passage. The intake pressure introduction passage 77 is provided with a switching valve 78 in the passage. In other words, the opening / closing valve 75 of the combination valve 74 is connected to the intake manifold 35 via the intake pressure introduction passage 77, and a switching valve 78 is provided in the middle thereof.

  As the switching valve 78, for example, an electromagnetic drive type switching valve is used, and the driving pressure of the on-off valve 75 of the combination valve 74 is switched between the atmospheric pressure and the intake pressure. The switching valve 78 is electrically connected to the ECU 51, and its driving is controlled by the ECU 51.

  The secondary air pressure sensor 79 is provided between the air pump 73 and the on-off valve 75 of the secondary air introduction passage 71, and measures and measures the pressure of the secondary air flowing through the secondary air introduction passage 71. Secondary air pressure is output to the ECU 51.

  Accordingly, when the secondary air is introduced into the exhaust manifold 46, the secondary air supply device 70 switches the switching valve 78 to the “ON position” that is the intake pressure introduction position under the control of the ECU 51. Then, the intake pressure is introduced into the on-off valve 75, and the on-off valve 75 is opened. Thereby, in the secondary air supply device 70, the secondary air discharged by the air pump 73 passes through the on-off valve 75 and flows to the check valve 76 side, and the check valve 76 is opened by the pressure. Air is introduced into the exhaust manifold 46.

  On the other hand, when the secondary air supply device 70 stops the introduction of the secondary air, the air pump 73 is stopped by the control of the ECU 51, and the switching valve 78 is set to the atmospheric pressure introduction position “OFF (off)”. By switching to “position”, the atmospheric pressure is introduced into the on-off valve 75 and the on-off valve 75 is closed. As a result, the secondary air supply device 70 stops the introduction of the secondary air into the exhaust manifold 46, and the pressure of the secondary air does not act on the check valve 76 and the pressure on the exhaust manifold 46 side is high. Therefore, the check valve 76 is automatically closed, and the exhaust gas in the exhaust manifold 46 is prevented from flowing back to the air pump 73 side.

  In the engine 10 configured as described above, when the piston 14 descends in the cylinder bore 13, air is sucked into the combustion chamber 18 through the intake port 19 (intake stroke), and the piston 14 falls under the intake stroke. The air is compressed by moving up in the cylinder bore 13 through the dead center (compression stroke). At this time, fuel is injected into the combustion chamber 18 from the injector 41 in the intake stroke or compression stroke, and this fuel and air mix to form an air-fuel mixture. When the piston 14 approaches the top dead center of the compression stroke, the air-fuel mixture is ignited by the spark plug 45, the air-fuel mixture burns, and the piston 14 is lowered by the combustion pressure (expansion stroke). The air-fuel mixture after combustion is discharged as exhaust gas through the exhaust port 20 when the piston 14 rises again toward the top dead center of the intake stroke via the expansion stroke bottom dead center (exhaust stroke). The reciprocating motion of the piston 14 in the cylinder bore 13 is transmitted to the crankshaft 16 through the connecting rod 17, where it is converted into a rotational motion and taken out as an output. When 16 further rotates due to inertial force, the cylinder bore 13 reciprocates as the crankshaft 16 rotates. By rotating the crankshaft 16 twice, the piston 14 reciprocates the cylinder bore 13 twice, during which a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke is performed, and once in the combustion chamber 18. Explosion takes place.

  At this time, the ECU 51 performs the air pump 73 and the switching valve 78 of the secondary air supply device 70 in a state where the three-way catalysts 48 and 49 are not sufficiently activated, such as when the engine 10 is cold started as described above. By controlling the driving of the exhaust gas, secondary air is supplied into the exhaust manifold 46, whereby oxygen in the secondary air can recombust unburned fuel components. Warm-up can be performed. When the three-way catalysts 48 and 49 are warmed up and sufficiently activated, the ECU 51 controls the driving of the air pump 73 and the switching valve 78 to stop (end) the supply of secondary air.

  Whether or not the secondary air supply control by the ECU 51 is to be stopped (terminated) can be determined by various determination methods. Here, the ECU 51 stops (ends) the secondary air supply control depending on whether or not the integrated intake air amount that is the integrated value of the intake air amount detected by the air flow sensor 52 has reached a predetermined integrated intake air amount determination value. ) Can be determined. That is, for example, the ECU 51 obtains an integrated intake air amount from the start of engine start of the intake air amount detected by the air flow sensor 52, and determines that the integrated intake air amount has reached a predetermined integrated intake air amount determination value. In this case, the driving of the air pump 73 and the switching valve 78 is controlled to stop the air pump 73 and the switching valve 78 is switched to the “OFF (off) position” to stop the secondary air supply control by the secondary air supply device 70. Execute control to

  Here, the ECU 51 stops the air pump 73 when the instantaneous intake air amount that is the instantaneous intake air amount detected by the air flow sensor 52 is determined to be larger than a predetermined instantaneous intake air amount determination value. The secondary air supply control by the secondary air supply device 70 is stopped. Thus, for example, when the instantaneous intake air amount becomes relatively large, the supply of the secondary air is temporarily stopped, and the secondary air flow rate (hereinafter simply referred to as “AI flow rate” unless otherwise specified). Can be suppressed. The ECU 51 operates the air pump 73 again when the instantaneous intake air amount becomes smaller than the predetermined instantaneous intake air amount determination value when the integrated intake air amount has not yet reached the predetermined integrated intake air amount determination value. The secondary air supply control is resumed. That is, this secondary air supply device 70 is used when the instantaneous intake air amount is equal to or less than the predetermined instantaneous intake air amount determination value under the condition that the integrated intake air amount has not yet reached the predetermined integrated intake air amount determination value. While controlling the ECU 51 to operate the air pump 73 to supply secondary air, the ECU 51 temporarily stops the air pump 73 when the instantaneous intake air amount is larger than a predetermined instantaneous intake air amount determination value. Control to temporarily stop the secondary air supply is executed.

  Here, the instantaneous intake air amount detected by the air flow sensor 52 is, for example, the intake air amount per unit time that can be detected by the air flow sensor 52. On the other hand, the integrated intake air amount detected by the air flow sensor 52 is an amount obtained by integrating the intake air amount (instantaneous intake air amount), and the ECU 51 detects the intake air amount (instantaneous intake air amount) detected by the air flow sensor 52. ) And the accumulated intake air amount can be stored in the storage unit 88 described later. In other words, the integrated intake air amount is obtained by integrating the intake air amount detected by the air flow sensor 52 after the supply of secondary air is started.

  By the way, the secondary air supply device 70 of the engine 10 has an altitude at which the vehicle on which the engine 10 is mounted travels, for example, when the integrated intake air amount determination value and the instantaneous intake air amount determination value described above are fixed determination values. As a result of the fluctuation, the operation period of the secondary air supply device 70 may become long, or unnecessary operation and stop may be repeated. Thereby, for example, there is a possibility that deterioration of the air pump 73 of the secondary air supply device 70 and the like easily proceeds.

  That is, as described above, the secondary air supply device 70 supplies outside air into the exhaust manifold 46 as secondary air. At this time, the altitude of the vehicle on which the engine 10 is mounted fluctuates, so that the pressure of the outside air supplied as the secondary air into the exhaust manifold 46 by the secondary air supply device 70, that is, the atmospheric pressure (hereinafter, particularly, Unless otherwise noted, it is simply abbreviated as “atmospheric pressure”.)

  When the vehicle equipped with the engine 10 is in a high altitude condition where the altitude is high, that is, in a condition where the atmospheric pressure surrounding the vehicle is a relatively low atmospheric pressure, the air density decreases, so that the vehicle has a low altitude. For example, when the piston 14 descends in the cylinder bore 13 and sucks air in the intake stroke, as compared with the case where the (lowland) condition, that is, the atmospheric pressure surrounding the vehicle is a relatively high atmospheric pressure condition, etc. The pumping loss is reduced, and the amount of intake air in a predetermined period is reduced. For this reason, when the integrated intake air amount determination value under high altitude conditions and the integrated intake air amount determination value under flat ground conditions are set to the same value, the intake air during a predetermined period when the vehicle is under high altitude conditions. Since the amount becomes relatively small, the period until the integrated intake air amount reaches a predetermined integrated intake air amount determination value becomes relatively long. As a result, for example, the operation period of the air pump 73 of the secondary air supply device 70 becomes longer, and the deterioration of the air pump 73 and the like is likely to proceed, whereby the life of the engine 10 provided with the secondary air supply device 70 is increased. May decrease.

  In addition, when the instantaneous intake air amount determination value under the high altitude condition and the instantaneous intake air amount determination value under the flat ground condition of the vehicle equipped with the engine 10 are set to the same value, the vehicle is in the flat ground condition. Since the instantaneous intake air amount is relatively large, there is a possibility that the operation and stop of the air pump 73 of the secondary air supply device 70 that is unnecessary are repeated. In particular, in consideration of high altitude conditions (low atmospheric pressure conditions) in which the discharge pressure of the air pump 73 is reduced, the instantaneous intake air amount determination value under the high altitude conditions is relatively compared to prevent the backflow of exhaust gas to the air pump 73 side. When the instantaneous intake air amount determination value under the flat ground condition is set to the same value as this, the frequency of repetition of operation and stop of the unnecessary air pump 73 of the secondary air supply device 70 is high. Tend to be. As a result, the frequency of repetition of the operation and stop of the air pump 73 is increased, so that the frequency of a large current flowing to the air pump 73 at the start of operation increases. As a result, damage to the air pump 73 is accumulated. The life of the engine 10 provided with the secondary air supply device 70 may be reduced.

  Therefore, as shown in FIG. 2, the secondary air supply device 70 of the engine 10 of the present embodiment is set to set a determination value for the intake air amount based on the atmospheric pressure corresponding to the altitude of the vehicle on which the engine 10 is mounted. A determination value setting unit 82 as means, and a secondary air control unit 81 as secondary air control means for controlling the operation of the secondary air supply device 70 based on the intake air amount and the determination value. By setting the determination value based on the atmospheric pressure, the setting unit 82 suppresses a prolonged operation period, unnecessary operation, and stop of the secondary air supply device 70, and suppresses a decrease in the life of the engine 10. Yes.

  Specifically, the ECU 51 of the present embodiment is provided with a secondary air control unit 81 and a determination value setting unit 82. The determination value setting unit 82 further serves as an integrated intake air amount determination value setting unit. An integrated intake air amount determination value setting unit 83, an instantaneous intake air amount determination value setting unit 84 as an instantaneous intake air amount determination value setting unit, and an integrated intake air amount determination value correction unit as an integrated intake air amount determination value correction unit 85 and an instantaneous intake air amount determination value correction unit 86 as an instantaneous intake air amount determination value correction means. The secondary air supply device 70 of the engine 10 includes an atmospheric pressure sensor 62 as atmospheric pressure detection means.

  The atmospheric pressure sensor 62 detects atmospheric pressure as the pressure of the outside air supplied as secondary air into the exhaust manifold 46 by the secondary air supply device 70, that is, the vehicle is set as a value corresponding to the altitude of the vehicle. It detects the atmospheric pressure surrounding it. The atmospheric pressure sensor 62 outputs the detected (measured) atmospheric pressure to the ECU 51.

  The ECU 51 includes a processing unit 87, a storage unit 88, and an input / output unit 89 that are configured with a microcomputer as a center, and are connected to each other so that signals can be exchanged with each other. The input / output unit 89 is connected to a drive circuit (not shown) that drives each unit including the secondary air supply device 70 of the engine 10 and the various sensors described above. The input / output unit 89 is connected to these sensors and the like. Input and output signals between them. The storage unit 88 stores a computer program for controlling each unit including the secondary air supply device 70 of the engine 10. The storage unit 88 is a hard disk device, a magneto-optical disk device, a non-volatile memory such as a flash memory (a storage medium that can be read only such as a CD-ROM), or a RAM (Random Access Memory). A volatile memory or a combination thereof can be used. The processing unit 87 includes a memory (not shown) and a CPU (Central Processing Unit). The above-described secondary air control unit 81, integrated intake air amount determination value setting unit 83, instantaneous intake air amount determination value setting unit 84, and a determination value setting unit 82 including an integrated intake air amount determination value correction unit 85 and an instantaneous intake air amount determination value correction unit 86. The secondary air supply control of the secondary air supply device 70 of the engine 10 described in FIG. 3 and FIG. 5 is based on the detection results of the sensors provided in the respective units. This is executed by reading into a memory incorporated in the memory and calculating, and sending a control signal according to the result of the calculation. At that time, the processing unit 87 appropriately stores a numerical value in the middle of the calculation in the storage unit 88, and takes out the stored numerical value and executes the calculation. In addition, when controlling this engine 10 and the secondary air supply apparatus 70, you may control by the dedicated hardware different from ECU51 instead of the said computer program.

  The secondary air control unit 81 operates the secondary air supply device 70 based on the intake air amount detected by the air flow sensor 52 and the determination value set for the intake air amount by the determination value setting unit 82. That is, the driving of the air pump 73 and the switching valve 78 is controlled.

  The determination value setting unit 82 sets a determination value for the intake air amount based on the atmospheric pressure detected by the atmospheric pressure sensor 62. Here, the determination value set for the intake air amount by the determination value setting unit 82 is based on the integrated intake air amount determination value set for the integrated intake air amount and the instantaneous intake air amount as described above. And the instantaneous intake air amount judgment value set. The integrated intake air amount determination value is set by the integrated intake air amount determination value setting unit 83 according to the operating state of the engine 10, and is corrected by the integrated intake air amount determination value correction unit 85 based on the atmospheric pressure. On the other hand, the instantaneous intake air amount determination value is set by the instantaneous intake air amount determination value setting unit 84 according to the operating state of the engine 10 and is corrected by the instantaneous intake air amount determination value correction unit 86 based on the atmospheric pressure.

  The integrated intake air amount determination value setting unit 83 sets an integrated intake air amount determination value serving as a reference according to the operating state of the engine 10. The integrated intake air amount determination value setting unit 83 calculates a reference integrated intake air amount determination value based on, for example, the engine coolant temperature detected by the water temperature sensor 58. Here, the ECU 51 stores, for example, a map of an integrated intake air amount determination value (for example, an integrated intake air amount determination value on a flat ground) that is a reference created in advance by experiments or the like according to operating conditions such as engine coolant temperature. The integrated intake air amount determination value setting unit 83 is stored in the unit 88, and the integrated intake air amount determination value setting unit 83 is based on the map indicating the relationship between the engine cooling water temperature and the reference integrated intake air amount determination value. An intake air amount determination value is calculated.

  Based on the atmospheric pressure detected by the atmospheric pressure sensor 62, the integrated intake air amount determination value correction unit 85 corrects the integrated intake air amount determination value serving as a reference calculated by the integrated intake air amount determination value setting unit 83. Specifically, the integrated intake air amount determination value correcting unit 85 determines the integrated intake air amount determination value when the atmospheric pressure is low atmospheric pressure (corresponding to a high altitude condition) and the integrated intake air when the atmospheric pressure is high atmospheric pressure (corresponding to a flat ground condition). Correct to a value smaller than the amount judgment value. For example, the integrated intake air amount determination value correction unit 85 calculates the integrated intake air amount determination value correction coefficient that is set according to the atmospheric pressure detected by the atmospheric pressure sensor 62. A new integrated intake air amount determination value after correction is calculated by multiplying the reference integrated intake air amount determination value.

  Here, the ECU 51 stores, for example, a map of an integrated intake air amount determination value correction coefficient created in advance by experiments or the like according to atmospheric pressure in the storage unit 88, and the integrated intake air amount determination value correction unit 85 The integrated intake air amount determination value correction coefficient is calculated from the atmospheric pressure detected by the atmospheric pressure sensor 62 based on the map indicating the relationship between the atmospheric pressure and the integrated intake air amount determination value correction coefficient, and the integrated intake air amount determination value is calculated. Based on the reference integrated intake air amount determination value calculated by the setting unit 83 and the integrated intake air amount determination value correction coefficient, a new integrated intake air amount determination value after correction is calculated. In other words, the integrated intake air amount determination value correction coefficient is such that the integrated intake air amount determination value correction coefficient (for example, a value smaller than 1.0) on the low atmospheric pressure side (corresponding to the high altitude condition) is on the high atmospheric pressure side. It is set to a value smaller than the integrated intake air amount determination value correction coefficient (e.g., upper limit value 1.0) in the flat ground condition. Accordingly, the integrated intake air amount determination value correction unit 85 corrects the integrated intake air amount determination value when the atmospheric pressure is low and low (corresponding to the high altitude condition) to a relatively small value, and also corrects the high intake pressure (flat land condition). The integrated intake air amount determination value can be corrected to a relatively large value.

  The secondary air control unit 81 controls the driving of the air pump 73 and the switching valve 78 when the integrated intake air amount is smaller than the integrated intake air amount determination value corrected by the integrated intake air amount determination value correction unit 85. Then, the air pump 73 is operated and the switching valve 78 is switched to the “ON (on) position”, and the secondary air supply control by the secondary air supply device 70 is executed. On the other hand, the secondary air control unit 81 controls the driving of the air pump 73 and the switching valve 78 when the integrated intake air amount is larger than the integrated intake air amount determination value corrected by the integrated intake air amount determination value correction unit 85. Then, the air pump 73 is stopped and the switching valve 78 is switched to the “OFF (off) position”, and the secondary air supply control by the secondary air supply device 70 is stopped.

  On the other hand, the instantaneous intake air amount determination value setting unit 84 sets a reference instantaneous intake air amount determination value according to the operating state of the engine 10. The instantaneous intake air amount determination value setting unit 84 calculates a reference instantaneous intake air amount determination value based on, for example, the engine coolant temperature detected by the water temperature sensor 58 and the current integrated intake air amount. Here, for example, the ECU 51 determines an instantaneous intake air amount determination value (for example, an instantaneous intake air amount determination value at high altitudes) that is a reference created in advance by experiments or the like according to operating conditions such as the engine coolant temperature and the integrated intake air amount. ) Is stored in the storage unit 88, and the instantaneous intake air amount determination value setting unit 84 is a map showing the relationship between the engine coolant temperature and the cumulative intake air amount and the reference instantaneous intake air amount determination value. Based on the engine cooling water temperature and the integrated intake air amount, a reference instantaneous intake air amount determination value is calculated.

  The instantaneous intake air amount determination value correcting unit 86 corrects the instantaneous intake air amount determination value serving as a reference calculated by the instantaneous intake air amount determination value setting unit 84 based on the atmospheric pressure detected by the atmospheric pressure sensor 62. Specifically, the instantaneous intake air amount determination value correction unit 86 sets the instantaneous intake air amount determination value when the atmospheric pressure is high atmospheric pressure (corresponding to a flat ground condition) and the instantaneous intake air when the atmospheric pressure is low atmospheric pressure (corresponding to a high altitude condition). Correct to a value larger than the amount judgment value. For example, the instantaneous intake air amount determination value correction unit 86 calculates an instantaneous intake air amount determination value correction coefficient that is set according to the atmospheric pressure detected by the atmospheric pressure sensor 62. By multiplying the reference instantaneous intake air amount determination value, a corrected new instantaneous intake air amount determination value is calculated.

  Here, for example, the ECU 51 stores a map of the instantaneous intake air amount determination value correction coefficient that is created in advance by experiments or the like according to the atmospheric pressure in the storage unit 88, and the instantaneous intake air amount determination value correction unit 86 is The instantaneous intake air amount determination value correction coefficient is calculated from the atmospheric pressure detected by the atmospheric pressure sensor 62 based on the map indicating the relationship between the atmospheric pressure and the instantaneous intake air amount determination value correction coefficient, and the instantaneous intake air amount determination value is calculated. Based on the reference instantaneous intake air amount determination value calculated by the setting unit 84 and the instantaneous intake air amount determination value correction coefficient, a new instantaneous intake air amount determination value after correction is calculated. In other words, the instantaneous intake air amount determination value correction coefficient is such that the instantaneous intake air amount determination value correction coefficient (for example, a value greater than 1.0) on the high atmospheric pressure side (corresponding to a flat ground condition) is on the low atmospheric pressure side. The instantaneous intake air amount determination value correction coefficient (e.g., equivalent to the high altitude condition) is set to a value larger than the lower limit value 1.0. Therefore, the instantaneous intake air amount determination value correcting unit 86 corrects the instantaneous intake air amount determination value when the atmospheric pressure is higher than the high atmospheric pressure (corresponding to the flat ground condition) to a relatively large value, and also reduces the instantaneous intake air amount determination value (high altitude condition). Can be corrected to a relatively small value.

  Then, the secondary air control unit 81 controls the driving of the air pump 73 when the instantaneous intake air amount is larger than the instantaneous intake air amount determination value corrected by the instantaneous intake air amount determination value correction unit 86, and the air pump 73 is controlled. Control is performed to temporarily stop and temporarily stop the secondary air supply. The secondary air control unit 81 drives the air pump 73 when the instantaneous intake air amount becomes smaller than the instantaneous intake air amount determination value under the condition that the integrated intake air amount has not yet reached the integrated intake air amount determination value. And the control to restart the secondary air supply by operating the air pump 73 again is executed.

  Next, the secondary air supply control based on the integrated intake air amount of the secondary air supply device 70 of the engine 10 according to the present embodiment will be described with reference to the flowchart of FIG.

  First, the ECU 51 takes in the atmospheric pressure detected by the atmospheric pressure sensor 62 (S100), takes in the engine cooling water temperature detected by the water temperature sensor 58, and the integrated intake air amount determination value setting unit 83 is stored in the storage unit 88 of the ECU 51. Based on the map indicating the relationship between the stored engine coolant temperature and the reference cumulative intake air amount determination value, the reference cumulative intake air amount determination value is calculated from the engine coolant temperature (S102).

  Next, the integrated intake air amount determination value correction unit 85 performs integrated intake from the atmospheric pressure detected by the atmospheric pressure sensor 62 in S100 based on a map showing the relationship between the atmospheric pressure and the integrated intake air amount determination value correction coefficient. An air amount determination value correction coefficient is calculated. Then, the integrated intake air amount determination value correcting unit 85 is based on the reference integrated intake air amount determination value and the integrated intake air amount determination value correction coefficient calculated by the integrated intake air amount determination value setting unit 83 in S102. Then, a new integrated intake air amount determination value after correction is calculated (S104). As a result, the integrated intake air amount determination value on the low atmospheric pressure side (corresponding to the highland condition) is corrected to a relatively small value, and the integrated intake air amount determination value on the high atmospheric pressure side (corresponding to the flatland condition) is relatively It is corrected to a large value.

  Then, the ECU 51 obtains the integrated intake air amount from the start of engine start of the intake air amount detected by the air flow sensor 52, and the secondary air control unit 81 and the integrated intake air amount in S104. The integrated intake air amount determination value corrected by the determination value correcting unit 85 is compared to determine whether or not the integrated intake air amount is greater than the integrated intake air amount determination value (S106). When the secondary air control unit 81 determines that the integrated intake air amount is larger than the integrated intake air amount determination value corrected by the integrated intake air amount determination value correction unit 85 (S106: Yes), the air pump 73 and the switching valve 78 are used. And the switching valve 78 is switched to the “OFF (off) position” to stop the secondary air supply control (AI) by the secondary air supply device 70 (S108). Transition to the control cycle.

  When the secondary air control unit 81 determines that the integrated intake air amount is equal to or less than the integrated intake air amount determination value after correction by the integrated intake air amount determination value correction unit 85 (S106: No), other secondary air It is determined whether a supply control (AI) start condition is satisfied (S110). If the secondary air control unit 81 determines that another secondary air supply control (AI) start condition is not satisfied (S110: No), the secondary air control unit 81 proceeds to the next control cycle. When the secondary air control unit 81 determines that another secondary air supply control (AI) start condition is satisfied (S110: Yes), the secondary air control unit 81 controls the drive of the air pump 73 and the switching valve 78 to control the air pump 73. At the same time, the switching valve 78 is switched to the “ON (on) position” to start the secondary air supply control (AI) (continue if it has already started) (S112), and shift to the next control cycle. . Here, as other secondary air supply control (AI) start conditions, for example, the elapsed time after the start of the engine 10 is a period immediately after the start of a predetermined value or less, and the engine cooling water temperature or the intake air temperature is a predetermined value or less. There are various known conditions such as a low temperature of the engine, a current engine load in a low load range of a predetermined value or less, and a diagnosis result of the secondary air supply device 70 by the failure diagnosis device being normal.

  FIG. 4 is a diagram for explaining secondary air supply control based on the integrated intake air amount of the secondary air supply device 70 provided in the engine 10, where the horizontal axis represents time, the vertical axis represents the integrated intake air amount, and AI. The flow rate.

  In the engine 10 configured as described above, the integrated intake air amount determination value correction unit 85 corrects the integrated intake air amount determination value on the low atmospheric pressure side (corresponding to the high altitude condition) to a relatively small value. The operation period of the secondary air supply device 70 when the vehicle equipped with the engine 10 is under high altitude conditions (under low atmospheric pressure conditions) can be suppressed. That is, for example, when the integrated intake air amount determination value corrected based on the atmospheric pressure by the integrated intake air amount determination value correcting unit 85 is used as the integrated intake air amount determination value, as shown by the solid line in FIG. As shown by the dotted line in the figure, the vehicle has a higher altitude as compared with the case where the reference integrated intake air amount determination value (for example, the integrated intake air amount determination value on flat ground) is used as it is as the integrated intake air amount determination value. Even if the air density decreases under high altitude conditions (under low atmospheric pressure conditions), the integrated intake air amount judgment value on the low atmospheric pressure side (corresponding to high altitude conditions) is corrected to a relatively small value. The time A when the integrated intake air amount reaches the corrected integrated intake air amount determination value is shorter than the time B when it reaches the reference integrated intake air amount determination value. As a result, the operation period of the air pump 73 of the secondary air supply device 70 under high altitude conditions (low atmospheric pressure conditions) can be suppressed short. In this figure, after the air pump 73 is stopped, the AI flow rate is 0 with a slight time difference.

  Next, secondary air supply control based on the instantaneous intake air amount of the secondary air supply device 70 of the engine 10 according to the present embodiment will be described with reference to the flowchart of FIG.

  First, the ECU 51 takes in the atmospheric pressure detected by the atmospheric pressure sensor 62 (S200), takes in the engine cooling water temperature detected by the water temperature sensor 58 and the integrated intake air amount up to now, and sets the instantaneous intake air amount determination value setting unit 84. Is based on the engine cooling water temperature and the cumulative intake air amount based on a map showing the relationship between the engine cooling water temperature and the cumulative intake air amount stored in the storage unit 88 of the ECU 51 and the reference instantaneous intake air amount determination value. The instantaneous intake air amount determination value is calculated (S202).

  Next, the instantaneous intake air amount determination value correction unit 86 performs instantaneous intake from the atmospheric pressure detected by the atmospheric pressure sensor 62 in S200 based on a map indicating the relationship between the atmospheric pressure and the instantaneous intake air amount determination value correction coefficient. An air amount determination value correction coefficient is calculated. Then, the instantaneous intake air amount determination value correction unit 86 is based on the instantaneous intake air amount determination value and the instantaneous intake air amount determination value correction coefficient that are the reference calculated by the instantaneous intake air amount determination value setting unit 84 in S202. Then, a new instantaneous intake air amount determination value after correction is calculated (S204). As a result, the instantaneous intake air amount determination value on the high atmospheric pressure side (corresponding to flat ground conditions) is corrected to a relatively large value, and the instantaneous intake air amount determination value on the low atmospheric pressure side (corresponding to high ground conditions) is relatively It is corrected to a small value.

  Then, the secondary air control unit 81 compares the instantaneous intake air amount detected by the air flow sensor 52 with the instantaneous intake air amount determination value corrected by the instantaneous intake air amount determination value correction unit 86 in S204, It is determined whether or not the instantaneous intake air amount is larger than the instantaneous intake air amount determination value (S206). When the secondary air control unit 81 determines that the instantaneous intake air amount is larger than the instantaneous intake air amount determination value corrected by the instantaneous intake air amount determination value correction unit 86 (S206: Yes), the drive of the air pump 73 is controlled. Then, the air pump 73 is temporarily stopped, the secondary air supply control (AI) by the secondary air supply device 70 is stopped (S208), and the process proceeds to the next control cycle.

  When the secondary air control unit 81 determines that the instantaneous intake air amount is equal to or less than the instantaneous intake air amount determination value after correction by the instantaneous intake air amount determination value correction unit 86 (S206: No), other secondary air It is determined whether a supply control (AI) start condition is satisfied (S210). If the secondary air control unit 81 determines that another secondary air supply control (AI) start condition is not satisfied (S210: No), the secondary air control unit 81 proceeds to the next control cycle as it is. When the secondary air control unit 81 determines that another secondary air supply control (AI) start condition is satisfied (S210: Yes), the secondary air control unit 81 controls the driving of the air pump 73, operates the air pump 73, and performs the secondary operation. The air supply control (AI) is resumed (or continued if it has already been resumed) (S212), and the process proceeds to the next control cycle.

  FIG. 6 is a diagram for explaining secondary air supply control based on the instantaneous intake air amount of the secondary air supply device 70 provided in the engine 10, where the horizontal axis represents time and the vertical axis represents the instantaneous intake air amount and AI. The flow rate.

  In the engine 10 configured as described above, the instantaneous intake air amount determination value correction unit 86 corrects the instantaneous intake air amount determination value on the high atmospheric pressure side (corresponding to the flat ground condition) to a relatively large value. The frequency of repetition of operation and stop of the secondary air supply device 70 when the vehicle equipped with the engine 10 is under a flat ground condition (a high atmospheric pressure condition) can be suppressed. That is, for example, when the instantaneous intake air amount determination value corrected based on the atmospheric pressure by the instantaneous intake air amount determination value correction unit 86 is used as the instantaneous intake air amount determination value, as shown by the solid line in FIG. Compared to the case where the instantaneous intake air amount determination value (for example, the instantaneous intake air amount determination value at high altitude) as a reference is used as it is as the instantaneous intake air amount determination value as shown by the dotted line in the figure, the high atmospheric pressure side (flat ground) The instantaneous intake air amount determination value in the equivalent condition) is corrected to a relatively large value, so that the number of times the instantaneous intake air amount reaches the corrected instantaneous intake air amount determination value, in other words, the air pump 73 The number of times of stoppage (one time of A1 in the figure) is less than the number of times (four times of B1, B2, B3, and B4 in the figure) of reaching the reference instantaneous intake air amount determination value. As a result, unnecessary operation and stop of the air pump 73 of the secondary air supply device 70 under flat ground conditions (high atmospheric pressure conditions) can be suppressed, and the operation and stop of the air pump 73 of the secondary air supply device 70 can be suppressed. The frequency of repetition can be suppressed. Also in this figure, after the air pump 73 is stopped, the AI flow rate becomes 0 with a slight time difference.

  As a result, the secondary air supply device 70 of the engine 10 changes the altitude of the vehicle on which the engine 10 is mounted, and the atmospheric pressure of the outside air supplied as secondary air into the exhaust manifold 46 by the secondary air supply device 70 is increased. Even if it fluctuates, the integrated intake air amount determination value and the instantaneous intake air amount determination value are set according to the atmospheric pressure by the determination value setting unit 82, so that the air pump 73 operates under high altitude conditions (low atmospheric pressure conditions). The period can be suppressed to a short time, and the frequency of repeated operation and stop of the air pump 73 under flat ground conditions (high atmospheric pressure conditions) is suppressed, and the frequency of large current flowing to the air pump 73 at the start of operation is suppressed. Therefore, the progress of the deterioration of the air pump 73 can be suppressed, and the decrease in the life of the engine 10 provided with the secondary air supply device 70 can be suppressed. It can be.

  According to the engine 10 according to the embodiment of the present invention described above, the secondary air supply device 70 capable of supplying secondary air to the exhaust manifold 46 that exhausts the exhaust gas from the combustion chamber 18 and the suction to the combustion chamber 18. An air flow sensor 52 for detecting the amount of intake air, an atmospheric pressure sensor 62 for detecting atmospheric pressure, a determination value setting unit 82 for setting a determination value for the amount of intake air based on the atmospheric pressure, and an amount of intake air And a secondary air control unit 81 that controls the operation of the secondary air supply device 70 based on the determination value.

  Therefore, when the determination value setting unit 82 sets the determination value based on the atmospheric pressure, the operation period of the secondary air supply device 70 and unnecessary operation and stop can be suppressed. It is possible to suppress a decrease in the lifetime.

  Furthermore, according to the engine 10 according to the embodiment of the present invention described above, the determination value setting unit 82 sets the integrated intake air amount determination value that is a determination value for the integrated intake air amount that is the integrated value of the intake air amount. The integrated intake air amount determination value setting unit 83 that is set according to the operating state, and the integrated intake air amount determination value correction unit 85 that corrects the integrated intake air amount determination value based on the atmospheric pressure. The determination value correction unit 85 corrects the integrated intake air amount determination value when the atmospheric pressure is low on the low atmospheric pressure side to a value smaller than the integrated intake air amount determination value on the high atmospheric pressure side, and the secondary air control unit 81 detects the integrated intake air amount. When the air amount is smaller than the corrected integrated intake air amount determination value, the air pump 73 of the secondary air supply device 70 is controlled to be in an operating state, while the integrated intake air amount is larger than the corrected integrated intake air amount determination value. Second Controlling the air pump 73 of the air supply apparatus 70 in a stopped state.

  Therefore, even if the vehicle equipped with the engine 10 is under high altitude conditions (low atmospheric pressure conditions) at high altitude and the air density is reduced, the integrated intake air amount determination value correction unit 85 causes the low atmospheric pressure side (high altitude conditions). Is corrected to a relatively small value, the period until the integrated intake air amount reaches the integrated intake air amount determination value is shortened. The operation period of the air pump 73 of the secondary air supply device 70 (under low atmospheric pressure conditions) can be suppressed to be short, and deterioration of the air pump 73 can be suppressed.

  Furthermore, according to the engine 10 according to the embodiment of the present invention described above, the determination value setting unit 82 operates the instantaneous intake air amount determination value that is a determination value for the instantaneous intake air amount that is the instantaneous intake air amount. An instantaneous intake air amount determination value setting unit 84 that is set according to the state; and an instantaneous intake air amount determination value correction unit 86 that corrects the instantaneous intake air amount determination value based on atmospheric pressure. The value correction unit 86 corrects the instantaneous intake air amount determination value when the atmospheric pressure is high atmospheric pressure side to a value larger than the instantaneous intake air amount determination value when the atmospheric pressure side is low, and the secondary air control unit 81 corrects the instantaneous intake air amount. When the amount is larger than the corrected instantaneous intake air amount determination value, the air pump 73 of the secondary air supply device 70 is controlled to be stopped.

  Therefore, even when the vehicle equipped with the engine 10 is under a flat ground condition (high atmospheric pressure condition) at a low altitude, the instantaneous intake air on the high atmospheric pressure side (corresponding to the flat ground condition) is detected by the instantaneous intake air amount determination value correction unit 86. By correcting the amount determination value to a relatively large value, the number of times the instantaneous intake air amount reaches the instantaneous intake air amount determination value is suppressed, and as a result, unnecessary under flat ground conditions (high atmospheric pressure conditions). The operation and stop of the air pump 73 of the secondary air supply device 70 can be suppressed, the frequency of repeated operation and stop of the air pump 73 of the secondary air supply device 70 can be suppressed, and deterioration of the air pump 73 can be prevented. Can be suppressed.

  The engine 10 according to the above-described embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope described in the claims. In the above description, the internal combustion engine of the present invention is applied to a cylinder injection type multi-cylinder engine. However, the present invention is not limited to this type of engine, but can be applied to an in-line type or a V type engine. Even if it is applied to the internal combustion engine of the type, the same effect can be obtained. In the above description, the secondary air is described as being supplied to the upstream side of the three-way catalyst 48 of the exhaust manifold 46 serving as an exhaust passage. However, the secondary air may be supplied to the exhaust port 20 serving as an exhaust passage. .

  As described above, the internal combustion engine according to the present invention can suppress a decrease in life, and is suitable for use in various internal combustion engines that supply secondary air to the exhaust passage.

1 is a schematic configuration diagram of an engine according to an embodiment of the present invention. It is a schematic structure figure of the secondary air supply device of the engine concerning the embodiment of the present invention. It is a flowchart explaining the secondary air supply control based on the integrated intake air amount of the engine which concerns on embodiment of this invention. It is a diagram explaining the secondary air supply control based on the integrated intake air amount of the engine according to the embodiment of the present invention. It is a flowchart explaining the secondary air supply control based on the instantaneous intake air amount of the engine which concerns on embodiment of this invention. It is a diagram explaining secondary air supply control based on the instantaneous intake air amount of the engine concerning the embodiment of the present invention.

Explanation of symbols

10 Engine (Internal combustion engine)
18 Combustion chamber 20 Exhaust port 46 Exhaust manifold (exhaust passage)
47 Exhaust pipes 48, 49 Three-way catalyst 51 ECU
52 Air flow sensor (intake air amount detection means)
62 Atmospheric pressure sensor (atmospheric pressure detection means)
70 Secondary air supply device (secondary air supply means)
71 Secondary air introduction passage 72 Air filter 73 Air pump 74 Combination valve 75 On-off valve 76 Check valve 77 Intake pressure introduction passage 78 Switching valve 79 Secondary air pressure sensor 81 Secondary air control unit (secondary air control means)
82 judgment value setting section (setting means)
83 Integrated intake air amount determination value setting unit (Integrated intake air amount determination value setting means)
84 Instantaneous intake air amount determination value setting unit (instantaneous intake air amount determination value setting means)
85 Integrated intake air amount determination value correction unit (Integrated intake air amount determination value correction means)
86 Instantaneous intake air amount determination value correction unit (instantaneous intake air amount determination value correction means)

Claims (3)

Secondary air supply means capable of supplying secondary air to an exhaust passage for discharging exhaust gas from the combustion chamber;
An intake air amount detection means for detecting an intake air amount of air sucked into the combustion chamber;
Atmospheric pressure detecting means for detecting atmospheric pressure;
Setting means for setting a determination value for the intake air amount based on the atmospheric pressure;
A secondary air control means for controlling the operation of the secondary air supply means based on the intake air amount and the determination value;
Internal combustion engine. The setting means includes an integrated intake air amount determination value setting means for setting an integrated intake air amount determination value, which is a determination value for the integrated intake air amount, which is an integrated value of the intake air amount, according to an operating state; and the atmospheric pressure And an integrated intake air amount determination value correction unit that corrects the integrated intake air amount determination value based on the integrated intake air amount determination value correction unit, wherein the integrated intake air amount determination value correction unit includes the integrated intake air at a low atmospheric pressure side. The amount determination value is corrected to a value smaller than the integrated intake air amount determination value on the high atmospheric pressure side,
The secondary air control means controls the secondary air supply means to be in an operating state when the integrated intake air amount is smaller than the corrected integrated intake air amount determination value, while the integrated intake air amount is The secondary air supply means is controlled to be in a stopped state when the correction is greater than the integrated intake air amount determination value after correction,
The internal combustion engine according to claim 1. The setting means includes an instantaneous intake air amount determination value setting means for setting an instantaneous intake air amount determination value, which is a determination value for the instantaneous intake air amount that is the instantaneous intake air amount, according to an operating state; And an instantaneous intake air amount determination value correction unit that corrects the instantaneous intake air amount determination value based on the instantaneous intake air amount determination value correction unit. The instantaneous intake air amount determination value correction unit corrects the instantaneous intake air amount on the high atmospheric pressure side. The determination value is corrected to a value larger than the instantaneous intake air amount determination value on the low atmospheric pressure side,
The secondary air control means controls the secondary air supply means to a stop state when the instantaneous intake air amount is larger than the corrected instantaneous intake air amount determination value.
The internal combustion engine according to claim 1 or 2.

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