JP2007247628A - Exhaust valve control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust valve control device for an internal combustion engine capable of controlling a sliding amount of a slave piston without depending on a state of working fluid, to stabilize amount of a valve lift of an exhaust valve in a suitable value, and to restrain dispersion of engine brake force and an internal exhaust gas recirculation amount. <P>SOLUTION: A position sensor 80 and a hydraulic control valve 82 are disposed in a hydraulic operation mechanism 70, and the working fluid acting on the slave piston 74 is delivered by the hydraulic control valve in accordance with slave piston position information detected by the position sensor, to control an oil pressure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust valve control device for an internal combustion engine capable of opening an exhaust valve by hydraulic pressure.

Conventionally, with the aim of increasing the engine braking force by opening the exhaust valve just before the top dead center of the compression stroke, the so-called power tard, and the internal EGR effect by opening the exhaust valve during the intake stroke, There is an exhaust valve control device that controls an exhaust valve at a timing different from normal exhaust timing.
Specifically, a master piston that is pressed by a cam to generate hydraulic pressure immediately before the top dead center of the compression stroke or during an intake stroke, and receives the hydraulic pressure generated from the master piston that is connected to the master piston through an oil passage. And a slave piston that opens and opens the exhaust valve.

However, in this configuration, the hydraulic pressure generated by the master piston is uniquely determined by the cam, and it is impossible to adjust the sliding amount of the slave piston, that is, the valve lift amount of the exhaust valve.
Therefore, an oil passage connecting the master piston and the slave piston is provided with a piston that is displaced in the cylinder by an actuator, and the oil pressure is controlled by changing the volume of the oil passage according to the operating condition of the engine. A technique for adjusting the valve lift amount of a valve has been developed (see Patent Document 1).
JP 09-296740 A

However, the oil pressure received by the slave piston changes depending on the conditions such as the oil temperature of the hydraulic oil and the engine speed, and the technique disclosed in Patent Document 1 also depends on the state of the hydraulic oil, so the change As a result, the valve lift amount changes, and there is a problem that the engine braking force and the internal EGR amount vary.
The present invention has been made to solve such a problem, and an object of the present invention is to make it possible to control the sliding amount of the slave piston without depending on the state of the hydraulic oil, so that the valve of the exhaust valve can be controlled. An object of the present invention is to provide an exhaust valve control device for an internal combustion engine that can adjust the lift amount to an appropriate value and suppress variations in engine braking force and internal EGR amount.

  In order to achieve the above-described object, in the exhaust valve control device for an internal combustion engine according to claim 1, an exhaust valve provided in a cylinder head of the internal combustion engine for communicating and blocking between a combustion chamber and an exhaust port, and the internal combustion engine Hydraulic pressure generating means for generating hydraulic pressure by being actuated by a cam interlocking with the rotation of the motor, and the hydraulic pressure generating means is connected to the hydraulic pressure generating means via an oil passage, and slides by the hydraulic pressure generated by the hydraulic pressure generating means to open the exhaust valve. Hydraulic operation means having a slave piston to be valved, hydraulic oil supply / discharge means for supplying and discharging hydraulic oil from a hydraulic oil source of the internal combustion engine to the hydraulic pressure generation means, the oil passage and the hydraulic pressure operation means, and the slave Slave piston position detecting means for detecting the sliding position of the piston, and hydraulic pressure capable of changing the hydraulic pressure applied to the slave piston by discharging the hydraulic oil acting on the slave piston And valves, is characterized in that a hydraulic control means for controlling said hydraulic pressure control valve so as to vary the hydraulic pressure depending on the position of the slave piston which is detected by the slave piston position detecting means.

That is, in an internal combustion engine having a slave piston that opens the exhaust valve by receiving hydraulic pressure, hydraulic pressure is controlled by discharging hydraulic oil acting on the slave piston by the hydraulic control valve according to the sliding position of the slave piston. By adjusting the lift amount of the valve.
The exhaust valve control device for an internal combustion engine according to claim 2, wherein the hydraulic control means supplies hydraulic oil from the hydraulic pressure generating means, the oil passage, and the hydraulic pressure operating means by the hydraulic oil supply / discharge means. When discharging, the hydraulic oil acting on the slave piston is also discharged by the hydraulic control valve.

  That is, when the hydraulic oil is discharged by the hydraulic oil supply / discharge means, the hydraulic oil acting on the slave piston is discharged also by the hydraulic control valve.

According to the first aspect, the hydraulic pressure is controlled by discharging the hydraulic oil acting on the slave piston by the hydraulic control valve according to the sliding position of the slave piston, so that the slave piston does not depend on the state of the hydraulic oil. The sliding amount can be arbitrarily controlled.
Thereby, the valve lift amount of the exhaust valve can be adjusted to an appropriate value and stabilized, and the occurrence of variations in engine braking force and internal EGR amount can be suppressed.

According to the second aspect, when the hydraulic oil generating means, the oil passage, and the hydraulic oil in the hydraulic pressure operating means are discharged by the hydraulic oil supply / discharge means, the hydraulic oil acting on the slave piston is discharged by the hydraulic control valve. The power tard and internal EGR can be stopped early.
Thereby, the responsiveness in a power tard stop and internal EGR stop can be improved, and generation | occurrence | production of the dispersion | variation in engine brake force and internal EGR amount can be suppressed more reliably.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Referring to FIG. 1, there is shown a schematic configuration diagram of an exhaust valve control device for an internal combustion engine according to the present invention.
An engine 1 (internal combustion engine) shown in FIG. 1 is configured as a multi-cylinder diesel engine having two intake / exhaust valves per cylinder, and FIG. 1 shows a longitudinal section of one of the cylinders. ing. In addition, illustration and description are abbreviate | omitted as what has the same structure also about another cylinder.

As shown in FIG. 1, the engine 1 is configured with a cylinder head 4 mounted on a cylinder block 2.
A cylinder 6 is formed in the cylinder block 2, and a piston 8 is provided in the cylinder 6 so as to be slidable up and down.
The cylinder head 4 is provided with an injector (not shown) so as to face the cylinder 6.

The cylinder head 4 has two exhaust openings 10 a and 10 b formed on the lower surface thereof corresponding to the cylinder 6, and an exhaust port 10 extending from the exhaust openings 10 a and 10 b to the side surface of the engine 1 is formed. Has been.
The cylinder head 4 is slidably provided with a pair of exhaust valves 16 and 18 that are urged toward the valve closing side by valve springs 12 and 14 to close the exhaust ports 10a and 10b. The upper ends of the exhaust valves 16 and 18 are connected by a lifter 20.

Further, a rocker shaft 22 is provided on the upper portion of the cylinder head 4, and a rocker arm 24 is rotatably supported on the rocker shaft 22. One end of the rocker arm 24 is in contact with the upper portion of the lifter 20.
Further, a camshaft 26 that rotates in synchronization with the vertical movement of the piston 8 is provided at the upper part of the cylinder head 4, and the cam 28 formed on the camshaft 26 is in contact with the other end of the rocker arm 24. ing.

As the camshaft 26 rotates, the cam 28 pushes up the other end of the rocker arm 24 during the exhaust stroke, so that the rocker arm 24 swings around the rocker shaft 22 and one end of the rocker arm 24 pushes down the lifter 20. Thus, the exhaust valves 16 and 18 are opened.
Although not shown, the intake valve is similarly configured, and the intake port is opened during the intake stroke in synchronization with the rotation of the camshaft 26.

  Further, in addition to a cam for driving a normal intake / exhaust valve like the cam 28, the camshaft 26 is formed with a power-tard cam 29 for each cylinder. Further, a master piston 32 of a hydraulic pressure generating mechanism 30 (hydraulic pressure generating means) is provided at an upper position of the cylinder head 4 at a position close to the power tard cam 29, and the power tard cam 29 is dead in the compression stroke of the corresponding cylinder. It is formed so as to press the master piston 32 immediately before the point.

The master piston 32 is slidably accommodated in a master cylinder 36 of the master piston housing 34. The master piston 32 is pressed and slid by the power tod cam 29 just before the top dead center of the compression stroke of the corresponding cylinder, thereby pressurizing the hydraulic oil filled in the master cylinder 36 and increasing the hydraulic pressure. It has a function to generate.
The master cylinder 36 communicates with one end of the oil passage 40, and the other end of the oil passage 40 is connected to a control valve 50 provided on the upper portion of the exhaust valve 16 of the cylinder head 4.

  The control valve 50 is connected to a hydraulic operation mechanism 70 (hydraulic operation means) formed in the same housing 52 as the control valve 50 through an oil passage 42. Further, the control valve 50 is connected to a solenoid valve 44 (operating oil supply / discharge means) connected to an oil pump (not shown) via an oil passage 46. That is, the control valve 50 is connected to three oil passages: an oil passage 40 on the hydraulic pressure generating mechanism 30 side, an oil passage 42 on the hydraulic operation mechanism 70 side, and an oil passage 46 on the solenoid valve 44 side.

  Specifically, the control valve 50 includes a valve spring 59 in a control valve cylinder 58 in which a drain hole 54 is formed on the upper side and an oil inlet 56 connected to the oil passage 46 on the solenoid valve 44 side is formed on the lower side. A configuration in which a cylindrical valve body 62 incorporating a check ball 60 that forms a check valve biased downward and a return spring 64 that biases the valve body 62 from above to the oil inlet 56 side are housed. I am doing.

  When the hydraulic oil pumped from the oil pump through the solenoid valve 44 flows into the control valve 50 from the oil inlet 56, the check ball 60 is pushed up against the valve spring 59 and the valve body 62 is raised. In addition, the oil passage 46 on the solenoid valve 44 side, the oil passage 40 on the hydraulic pressure generating mechanism 30 side, and the oil passage 42 on the hydraulic operating mechanism 70 side have a function of communicating.

  The solenoid valve 44 has a function of supplying hydraulic oil to the control valve 50, the oil passages 40 and 42, the hydraulic operation mechanism 70, and the hydraulic pressure generation mechanism 30 of each cylinder through an oil passage 46 from an oil pump as a hydraulic oil source. And has a function of discharging the hydraulic oil. When the hydraulic oil is discharged by the solenoid valve 44, the check ball 60 and the valve body 62 in the control valve 50 are lowered to close the oil inlet 56, and thereafter the oil passage on the hydraulic pressure generating mechanism 30 side. The hydraulic pressure generated from the hydraulic pressure generating mechanism 30 is released from the drain hole 54 in communication with the hydraulic pressure 40.

Further, a hydraulic operation mechanism 70 formed in the same housing 52 as the control valve 50 includes a slave piston 74 provided in a slave cylinder 72 communicating with the oil passage 42 so as to be slidable up and down, and the slave It comprises a slave spring 76 that urges the piston 74 upward.
The lower end of the slave piston 74 is in contact with the upper end of the pin member 78 provided on the lifter 20, and the lower end of the pin member 78 is in contact with the upper end of the exhaust valve 16. The pin member 78 is supported so as to be vertically slidable with respect to the lifter 20, and is configured to be able to operate separately from the vertical movement of the lifter 20.

When the pressure in the slave cylinder 72 is increased, the hydraulic operating mechanism 70 has a function of opening the exhaust valve 16 via the pin member 78 by the slave piston 74 being pushed downward against the slave spring 76. Have.
A position sensor 80 (slave piston position detecting means) for detecting the sliding position of the slave piston 74 is provided on the outer peripheral side portion of the slave piston 74 of the housing 52, and a slave cylinder 72 is provided above the housing 52. A hydraulic control valve 82 (hydraulic control valve) capable of discharging the hydraulic oil stored therein is provided.

Specifically, the position sensor 80 is configured by a Hall element, and has a function of detecting the vertical sliding position of the slave piston 74 and outputting the detected slave piston position information to the ECU 90 mounted on the vehicle. Yes. However, in the present invention, the position sensor 80 is not limited to one using a Hall element.
The hydraulic control valve 82 is a solenoid valve and is controlled by the ECU 90 (hydraulic control means).

In addition to this, the ECU 90 has a function of controlling various devices such as the solenoid valve 44.
The operation of the exhaust valve control apparatus for an internal combustion engine according to the present invention configured as described above will be described below.
In the engine 1 having the above configuration, the power 90 is controlled by the ECU 90 by being switched to the power mode by the operation of the driver.

Specifically, the ECU 90 controls the solenoid valve 44 to supply the hydraulic oil pressure-fed from the oil pump to the control valve 50 of each cylinder via the oil passage 46 when the deceleration of the vehicle is detected in the power tard mode.
When hydraulic oil from the solenoid valve 44 flows in from the oil inlet 56, the control valve 50, as described above, the oil passage 46 on the solenoid valve 44 side, the oil passage 40 on the hydraulic pressure generating mechanism 30 side, and the hydraulic operation mechanism 70. The oil passage 42 on the side becomes a communicating state, and the master cylinder 36 and the slave cylinder 72 are filled with the hydraulic oil through the oil passages 40 and 42.

  In this state, when the master piston 32 is pressed against the power tod cam 29 just before the top dead center of the compression stroke, hydraulic pressure is generated from the master cylinder 36, and the hydraulic pressure is transmitted to the control valve 50 via the oil passage 40. The Then, in the control valve 50, while the valve body 62 is raised, only the check ball 60 is pushed down by the hydraulic pressure from the master cylinder 36, and the oil passage 46 on the solenoid valve 44 side is shut off. That is, only the oil path 40 on the hydraulic pressure generating mechanism 30 side and the oil path 42 on the hydraulic operating mechanism 70 side are in communication, and the hydraulic pressure generated from the master cylinder 36 is transferred from the control valve 50 to the hydraulic operating mechanism 70 via the oil path 42. Is communicated.

In the hydraulic operation mechanism 70, the inside of the slave cylinder 72 is pressurized by the transmitted hydraulic pressure, and the slave piston 74 is pushed down against the slave spring 76. Then, the slave piston 74 opens the exhaust valve 16 via the pin member 78.
As described above, the exhaust valve 16 is opened immediately before the top dead center of the compression stroke, so that the compressed air in the cylinder 6 flows out to the exhaust port 10.

Then, the pressing of the master piston 32 by the power-tard cam 29 is completed and the hydraulic pressure returns to the original value, so that the slave piston 74 and the exhaust valve 16 are returned to their original positions and are closed.
As a result, a force that prevents the piston 6 from descending is generated in the expansion stroke, and an engine brake increasing action, that is, a power tard is obtained.

When the power tard control is stopped by the driver's operation, the ECU 90 controls the solenoid valve 44 to shut off the hydraulic oil pumped from the oil pump, discharge the hydraulic oil from the oil passage 46, and also hydraulic pressure. The hydraulic oil in the slave cylinder 72 is discharged by the control valve 82.
Here, in the initial setting, the engine 1 is in such a condition that the hydraulic oil is in a low oil temperature state or the engine 1 is in a low engine rotation speed state, that is, the hydraulic pressure acting on the slave piston 74 is the lowest. Under the condition, the sliding amount of the slave piston 74, that is, the valve lift amount of the exhaust valve 16 is maximized. For example, this is done by adjusting the valve spring 59 of the check ball 60 or the like.

  Then, when the oil temperature of the hydraulic oil rises or the rotational speed of the engine 1 rises, the hydraulic pressure of the hydraulic oil increases, and the sliding amount of the slave piston 74 immediately before the top dead center of the compression stroke increases. At this time, if the ECU 90 determines that the slave piston position detected by the position sensor 80 is below the predetermined position, the ECU 90 opens the hydraulic control valve 82 and discharges the hydraulic oil in the slave cylinder 72. As a result, the hydraulic pressure is reduced, and the sliding amount of the slave piston 74 is reduced to bring the slave piston position into a predetermined position.

The ECU 90 can make the valve lift amount of the exhaust valve 16 according to the operating state of the engine 1 by varying the predetermined position.
As described above, the hydraulic operation mechanism 70 is provided with the position sensor 80 and the hydraulic control valve 82, and the hydraulic oil that acts on the slave piston 74 by the hydraulic control valve 82 according to the slave piston position information detected by the position sensor 80. By controlling the hydraulic pressure by discharging the oil, it is possible to arbitrarily control the sliding amount of the slave piston 74 without depending on the state of the hydraulic oil.

Thus, in the exhaust valve control device for an internal combustion engine according to the present invention, the valve lift amount of the exhaust valve 16 can be stabilized, and the occurrence of variations in engine braking force can be suppressed.
Further, when the power tard control is stopped, the hydraulic control valve 82 discharges the hydraulic oil in the slave cylinder 72, so that the power tard can be stopped early.
Thereby, the responsiveness in a power tard stop can be improved and generation | occurrence | production of the dispersion | variation in engine brake force can be suppressed more reliably.

Although the description of the embodiment of the exhaust valve control device for an internal combustion engine according to the present invention is finished above, the embodiment is not limited to the above embodiment.
For example, in the above embodiment, the power turd cam 29 that presses the master piston 32 just before the compression stroke top dead center is provided. However, the power turd cam 29 is used as an internal EGR cam that presses the master piston 32 during the intake stroke. It is possible to change the configuration so that the internal EGR for opening the exhaust valve 16 during the intake process can be executed.

In this way, the internal EGR can be executed, and the above control is performed to suppress variations in the internal EGR amount.
Moreover, it is good also as a structure which can provide a switching control valve and can perform both a power tard and internal EGR, and even if it is the said structure, the dispersion | variation in engine brake force and internal EGR amount can be suppressed by performing the said control.

1 is a schematic configuration diagram of an exhaust valve control device for an internal combustion engine according to the present invention.

Explanation of symbols

1 engine (internal combustion engine)
4 Cylinder head 16, 18 Exhaust valve 20 Lifter 28 Cam 29 Power tard cam 30 Hydraulic pressure generating mechanism (hydraulic pressure generating means)
32 Master piston 36 Master cylinder 40, 42, 46 Oil passage 44 Solenoid valve (hydraulic oil supply / discharge means)
50 Control valve 54 Drain hole (hydraulic oil supply / discharge means)
70 Hydraulic operating mechanism (hydraulic operating means)
72 Slave cylinder 74 Slave piston 78 Pin member 80 Position sensor (slave piston position detection means)
82 Hydraulic control valve (hydraulic control valve)
90 ECU (hydraulic control means)

Claims (2)

An exhaust valve that is provided in a cylinder head of the internal combustion engine and that communicates and shuts off the combustion chamber and the exhaust port;
A hydraulic pressure generating means for generating a hydraulic pressure by being actuated by a cam interlocking with the rotation of the internal combustion engine;
Hydraulic operation means having a slave piston that is connected to the oil pressure generation means via an oil passage and slides by the oil pressure generated by the oil pressure generation means to open the exhaust valve;
Hydraulic oil supply / discharge means for supplying and discharging hydraulic oil from the hydraulic oil source of the internal combustion engine to the hydraulic pressure generating means, the oil passage and the hydraulic pressure operating means;
Slave piston position detecting means for detecting the sliding position of the slave piston;
A hydraulic control valve capable of varying the hydraulic pressure applied to the slave piston by discharging hydraulic oil acting on the slave piston;
An exhaust valve control device for an internal combustion engine, comprising: hydraulic control means for controlling the hydraulic control valve so as to vary the hydraulic pressure in accordance with the position of the slave piston detected by the slave piston position detecting means. .   The hydraulic control means operates to act on the slave piston by the hydraulic control valve when the hydraulic oil is discharged from the hydraulic pressure generating means, the oil passage, and the hydraulic pressure operating means by the hydraulic oil supply / discharge means. The exhaust valve control device for an internal combustion engine according to claim 1, wherein the oil is discharged.

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