JP2022133866A - Control device for internal combustion engine - Google Patents

Abstract

To temporarily enhance the power performance of a vehicle as needed.SOLUTION: A control device for an internal combustion engine is configured to determine whether or not knocking occurs in a cylinder, when knocking is detected, gradually increase a retard correction amount to be added to base ignition timing until the knocking does not occur any longer, and when no knocking is detected, reduce the retard correction amount to be added to the base ignition timing, as long as knocking does not occur. The control device is configured to set the retard correction amount to zero or minimum in the case of satisfying conditions that a vehicle speed or an engine rotation speed is equal to or below a predetermined value, a state in which an accelerator is opened fully or to a predetermined value close to fully open or more continues for a predetermined time or longer, and acceleration of the vehicle speed or the engine rotation speed is equal to or below a predetermined value, or to correct the base ignition timing to be advanced as compared with the case where the conditions are not satisfied.SELECTED DRAWING: Figure 2

Description

The present invention relates to a control device for controlling an internal combustion engine mounted on a vehicle as a power source.

In a spark ignition type internal combustion engine, in principle, the ignition timing of the air-fuel mixture charged in the cylinder is set according to the operating range of the internal combustion engine at that time. The base ignition timing is determined by comparing the MBT (Minimum advance for Best Torque) in the operating range and the advance amount of ignition timing that is normally considered to be the limit at which knocking does not occur in the operating range. In the low load to medium load range, knocking does not occur even if the ignition timing is advanced to the MBT, so the MBT timing is used as the base ignition timing. On the other hand, in the high load region, there is a risk of knocking if the ignition timing is advanced to the MBT, so the base ignition timing needs to be delayed from the MBT timing.

In addition, the presence or absence of knocking in the cylinder is determined, and control of a so-called knock control system is performed to adjust the ignition timing according to the determination result. When knocking is detected, the ignition timing is gradually retarded until knocking no longer occurs, that is, the retardation correction amount added to the base ignition timing is gradually increased. On the other hand, when knocking is not detected, the ignition timing is gradually advanced as long as knocking does not occur, that is, the retardation correction amount added to the base ignition timing is decreased to improve the output and fuel efficiency of the internal combustion engine. (see, for example, the following patent documents).

JP 2019-132184 A

When the vehicle is traveling on a steep and steep uphill road, or when trying to climb over a high step to enter a parking lot, etc., the driver of the vehicle must press the accelerator pedal strongly from a low vehicle speed or low engine speed state. Perform stepping operation.

At this time, the internal combustion engine is operated in a low-rotation, high-load region where knocking is likely to occur. As a result, the knock control system described above operates to retard the ignition timing and limit the engine torque and engine output regardless of the driver's request. In an environment in which knocking can occur repeatedly, such as when the temperature of the internal combustion engine itself or the intake air temperature is high, the ignition timing retardation correction is increased, and the maximum power performance of the vehicle is reduced accordingly.

As a result, there were times when it was not possible to smoothly run a steep uphill road, or it was difficult to overcome a high step. In particular, when a compact car (a light car or a small car) equipped with a low-displacement internal combustion engine is loaded with a large number of people or heavy luggage, this problem becomes apparent.

SUMMARY OF THE INVENTION An object of the present invention, which has been made in view of the above points, is to make it possible to temporarily increase the power performance of a vehicle as needed.

The present invention is a control device for controlling an internal combustion engine mounted on a vehicle, in which it is determined whether or not knocking has occurred in a cylinder, and when knocking is detected, the current internal combustion engine is controlled until knocking no longer occurs. While gradually increasing the retardation correction amount added to the base ignition timing according to the operating range, when knocking is not sensed, the retardation correction amount added to the base ignition timing is decreased as long as knocking does not occur. When the vehicle speed or engine speed is at a low speed below a predetermined value and the accelerator is fully opened or close to a predetermined value or more, the state continues for a predetermined time or longer. and the acceleration of the vehicle speed or the acceleration of the engine speed is less than or equal to a predetermined value, the retardation correction amount is temporarily set to 0 or a minimum value, and the condition is satisfied. A control device for an internal combustion engine is configured to perform at least one of advancing and correcting the base ignition timing as compared with a case where the base ignition timing is not provided.

According to the present invention, the power performance of the vehicle can be temporarily enhanced as necessary, such as when the vehicle travels on an uphill road with a large gradient or when trying to climb over a high level difference.

1 is a diagram showing a schematic configuration of a vehicle internal combustion engine and a control device according to an embodiment of the present invention; FIG. FIG. 2 is a flow chart showing an example of the procedure of processing executed by the control device for an internal combustion engine according to the embodiment according to a program; FIG. 2 is a timing chart for explaining the contents of control by the control device for an internal combustion engine according to the embodiment;

One embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of a vehicle internal combustion engine according to this embodiment. The internal combustion engine of this embodiment is a port-injection, four-stroke, spark-ignited engine, and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). An injector 11 for injecting fuel toward the intake port is provided upstream of the intake valve of each cylinder 1 and in the vicinity of the intake port connected to each cylinder 1 . A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1 . The spark plug 12 receives an induced voltage generated by an ignition coil and induces spark discharge between a center electrode and a ground electrode. The ignition coil is integrally built into the coil case together with the igniter, which is a semiconductor switching element.

An intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1 . An air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order on the intake passage 3 from upstream.

An exhaust passage 4 for exhausting exhaust guides the exhaust generated as a result of burning fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42 and a three-way catalyst 41 for purifying exhaust gas are arranged on the exhaust passage 4 .

The exhaust gas recirculation device 2 includes an external EGR passage 21 that communicates the exhaust passage 4 and the intake passage 3, an EGR cooler 22 provided on the EGR passage 21, and an EGR passage 21 to open and close the EGR An EGR valve 23 for controlling the flow rate of EGR gas flowing through the passage 21 is included as an element. The inlet of the EGR passage 21 is connected to a predetermined location downstream of the catalyst 41 in the exhaust passage 4 . The outlet of the EGR passage 21 is connected to a predetermined location downstream of the throttle valve 32 in the intake passage 3 (in particular, the surge tank 33 or the intake manifold 34).

An ECU (Electronic Control Unit) 0, which is a control device for an internal combustion engine according to the present embodiment, is a microcomputer system having a processor, memory, input interface, output interface, and the like. The ECU 0 may be formed by connecting a plurality of ECUs or controllers so as to be able to communicate with each other via electric communication lines such as CAN (Controller Area Network).

The input interface of the ECU 0 receives a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed, a crank angle signal b output from a crank angle sensor that detects the rotation angle of the crankshaft of the internal combustion engine and the engine speed. , an accelerator opening signal c output from a sensor that detects the amount of depression of the accelerator pedal or the opening of the throttle valve 32 as the accelerator opening (so to speak, the required engine load factor or engine torque); 3 (downstream of the throttle valve 32, in particular, the surge tank 33 or the intake manifold 34) intake air temperature and intake pressure signal d output from the temperature / pressure sensor that detects the intake air temperature and pressure, the cooling water temperature of the internal combustion engine A cooling water temperature signal e output from a water temperature sensor that detects atmospheric pressure, an atmospheric pressure signal f output from an atmospheric pressure sensor that detects atmospheric pressure, and a vibration type sensor that detects the magnitude of vibration of a cylinder block containing cylinder 1. A vibration signal g output from a knock sensor, an air-fuel ratio signal h output from an air-fuel ratio sensor that detects the air-fuel ratio of exhaust gas flowing through the exhaust passage 4, and the like are input.

From the output interface of the ECU 0, an ignition signal i to the igniter, a fuel injection signal j to the injector 11, an opening operation signal k to the throttle valve 32, an opening operation signal l to the EGR valve 23, etc. Output.

The processor of the ECU0 interprets and executes programs stored in the memory, calculates operating parameters, and controls the operation of the internal combustion engine. The ECU 0 obtains various types of information a, b, c, d, e, f, g, and h necessary for control through an input interface, and as well as knowing the engine speed, determines the air intake into the cylinder 1 (fresh air). ) to estimate the amount. Then, the required fuel injection amount (which can achieve the stoichiometric air-fuel ratio or a target air-fuel ratio near it) that matches the intake air amount, the fuel injection timing (including the number of fuel injections for one combustion), the fuel injection pressure, Various operating parameters such as ignition timing (including the number of times of ignition for one combustion), required EGR rate (or EGR gas amount, EGR gas partial pressure), etc. are determined. The ECU 0 applies various control signals i, j, k, l corresponding to the operating parameters through the output interface.

In determining the spark ignition timing for the air-fuel mixture filled in each cylinder 1, the ECU 0 determines the current operating range of the internal combustion engine [engine speed, intake pressure of surge tank 33 or intake manifold 34 (or accelerator opening). engine speed, engine load factor, engine torque, intake air amount, fuel injection amount)], and a retard correction amount is added to the base ignition timing according to the presence or absence of knocking in cylinder 1. Add.

The base ignition timing is set at a timing that minimizes the possibility of knocking that can be perceived by the human ear and that maximizes the thermo-mechanical conversion efficiency of the internal combustion engine. The base ignition timing in the partial load region where the accelerator opening is not large is the MBT or its vicinity. The base ignition timing in the full-load or high-load region where the accelerator opening is fully open or nearly fully open lags MBT. The memory of the ECU 0 stores in advance map data defining the relationship between the parameters (engine speed, intake pressure, etc.) indicating the operating range of the internal combustion engine and the base ignition timing. The ECU 0 retrieves the map data using the current operating range parameter of the internal combustion engine as a key, and obtains the base ignition timing to be set.

After that, the ECU 0 determines whether or not knocking occurs in each cylinder 1 by referring to the output signal g of the knock sensor, and performs knock control control by adjusting the ignition timing according to the result of the determination. The ECU 0 of the present embodiment samples a vibration signal g indicating the strength of vibration of the cylinder 1 or the cylinder block, and passes frequency components (for example, 7 kHz to 15 kHz components) of vibrations caused by knocking. Input to a band-pass filter that attenuates components other than this vibration. Then, the value of the signal g after being processed by the bandpass filter is compared with the knock determination value, and if the former exceeds the latter, it is determined that knocking has occurred in cylinder 1 which has reached the expansion stroke. If the former is less than or equal to the latter, it is determined that the cylinder 1 is not knocking.

When the occurrence of knocking in cylinder 1 is detected, the ignition timing is gradually retarded until knocking no longer occurs, in other words, the retardation correction amount added to the base ignition timing is gradually increased. On the other hand, when the occurrence of knocking is not detected, the ignition timing is gradually advanced as long as knocking does not occur. Improve performance. The determination of the presence or absence of knocking and the correction of the ignition timing can be performed individually for each cylinder.

When the vehicle is traveling on a steep uphill road with a large gradient, or when trying to climb over a high step to enter a parking lot, etc., the driver must depress the accelerator pedal from a low vehicle speed or low engine speed state. perform the operation of strongly stepping on the . At this time, the internal combustion engine is in a low-rotation, high-load operating range in which knocking is likely to occur. When the above-described knock control control is performed, the ignition timing is retarded, and the thermomechanical conversion efficiency of the internal combustion engine is lowered, that is, the engine torque output by the internal combustion engine is limited. As a result, problems arise such as being unable to smoothly run a steep uphill road or being unable to overcome a high level difference.

In order to alleviate or avoid the above problem, the ECU 0 of the present embodiment, as shown in FIG. stop (step S2). The ECU 0 maintains a state in which the current vehicle speed or engine speed is at or below a predetermined value (for example, the vehicle speed is at or below 20 km/h) and the accelerator is fully opened or close to a predetermined value or more for a predetermined period of time. or more (for example, 10 seconds or more), and the vehicle speed or the acceleration of the engine speed is a predetermined value or less (for example, the acceleration of the vehicle speed is 20 km/h/s or less). It is judged that the condition of

In step S2, the ECU 0 sets the ignition timing retardation correction amount by the knock control system to 0 or a minimal value close to 0, regardless of whether or not the cylinder 1 is knocking. In short, temporarily ignore knocking.

In addition, the ECU 0 adds a predetermined advance correction amount to the base ignition timing corresponding to the current operating range of the internal combustion engine (step S3. For example, the base ignition timing is set to 3° CA (crank angle) to 5° CA advance). This is an advance amount that may induce mild knocking in cylinder 1 but does not induce severe knocking (heavy knocking).

Steps S2 and S3 both advance the ignition timing as compared to the normal case where knock control is performed, and further increase the thermo-mechanical conversion efficiency of the internal combustion engine, thereby increasing engine torque and engine output. is. When the condition of step S1 is satisfied, both steps S2 and S3 may be performed, or only one of them may be performed. If both steps S2 and S3 are executed, the spark ignition timing for the air-fuel mixture is advanced by 3°CA to 5°CA from the normal base ignition timing.

The control of steps S2 and/or S3 is terminated when a predetermined termination condition is satisfied (step S4), and thereafter normal knock control control (step S5) is resumed. The ECU 0 determines whether the driver's depression of the accelerator pedal is relaxed and the accelerator opening is reduced below a predetermined value, or the acceleration of the vehicle speed or the engine speed exceeds a predetermined value, or even if these conditions are not satisfied, step S1 is executed. It is determined that the condition of step S4 has been satisfied when a predetermined time (for example, several seconds, preferably a short period of time such that knocking does not damage the internal combustion engine) has elapsed since the condition was established.

FIG. 3 illustrates the pattern of control by the ECU 0 of this embodiment. In FIG. ₃ , the condition of step S1 is satisfied at time t1, and the condition of step S4 is satisfied at _time t2.

According to this embodiment, it is possible to temporarily advance the ignition timing to increase the engine torque and output when the vehicle is traveling on a steep uphill road or when trying to climb over a high step. becomes. Therefore, it is possible to ensure the necessary power performance to run a severe uphill road or climb over a high level difference, which contributes to the improvement of the drivability of the vehicle.

The present invention is not limited to the embodiments detailed above. Various modifications can be made to the specific configuration of each part, the procedure of processing, and the like without departing from the spirit of the present invention.

INDUSTRIAL APPLICABILITY The present invention can be applied to control of an internal combustion engine mounted on a vehicle.

0... Control unit (ECU)
1 Cylinder 12 Ignition plug a Vehicle speed signal b Crank angle signal f Accelerator opening signal g Knock sensor output signal i Ignition signal

Claims (1)

A control device for controlling an internal combustion engine mounted on a vehicle,
It is determined whether or not knocking has occurred in the cylinder, and when knocking is detected, the retard correction amount added to the base ignition timing according to the current operating range of the internal combustion engine is gradually increased until knocking does not occur. On the other hand, when knocking is not detected, as long as knocking does not occur, knock control control is performed to reduce the retardation correction amount added to the base ignition timing,
The vehicle speed or engine speed is at a low speed below a predetermined value, the accelerator pedal is fully open or close to full opening at or above a predetermined value, and has continued for a predetermined time or longer, and the vehicle speed or engine speed is accelerating. When a condition of low acceleration equal to or less than a predetermined value is satisfied, the retardation correction amount is temporarily set to 0 or minimized, and the base ignition timing is adjusted compared to when the condition is not satisfied. A control device for an internal combustion engine that performs at least one of advancing correction.

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