JPS62147016A - Control device for engine - Google Patents

Abstract

PURPOSE:To improve ignition performance by providing a rotary valve linked with engine rotation in a suction passage whereby controlling a period of time for suction during a period of time for a suction valve left open by opening and closing the timing of the rotary valve in such a way that compression ratio is made high for a short period of time for suction. CONSTITUTION:An auxiliary suction passage 20B is provided in a suction passage 20 bypassing a shutter valve 28 which opens at the high rotary speed of an engine, and is also provided with a rotary valve 30 rotating accompanied with a crank shaft 32. The rotation timing of the rotary valve 30 is controlled in such a way that a period of time for opening the suction passage will be long during a period of time for a suction valve left open depending on an increase in the rotary speed of the engine. A piston 54 provided on the upper section of a cylinder 10 is driven by a hydraulic device 56 in such a way that when a substantial period of time for suction is short at low load, the piston 54 is lowered by means of a control unit 100 for increasing pressure so as to compensate a substantial drop in compression ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is directed to an engine in which an intake passage opening/closing means such as an intake valve or a timing valve is disposed in an intake passage connected to a combustion chamber of an engine. The present invention relates to a control device for an engine that supplies intake air to a combustion chamber when the engine is in an open state.

(Prior art) Generally, in a heat engine, when the thermal energy from the combustion of fuel is converted into mechanical work and extracted as output, a part of the thermal energy is lost as a pumping loss. BACKGROUND ART BACKGROUND ART In engines such as gasoline engines, pumping loss that occurs during the intake stroke due to negative pressure acting on the piston within the cylinder is viewed as a problem. In particular, when the engine is in a low-load operating state in which the negative pressure acting on the piston in the cylinder increases during the intake stroke, the pumping loss becomes relatively large.

Conventionally, in order to reduce such pumping loss, for example, as shown in FIG.
2. Intake valve 14. An intake passage 20 and an exhaust passage 22 communicate with a combustion chamber 10 surrounded by an exhaust valve 16 and the like via an intake valve 14 and an exhaust valve 16, respectively.
In an engine in which output is taken out through a crankshaft connected to a piston 12, a timing valve 24 is disposed in an intake passage 20, and this timing valve 24 is connected to the intake valve 1.
It is known that the intake passage opening/closing means is configured to be closed at a time prior to 4, and the intake valve 14 and the timing valve 24 constitute an intake passage opening/closing means.

In the engine configured in this manner, the opening/closing timing of the timing valve 24 is changed according to the amount of operation of an accelerator operating means such as an accelerator pedal, and thereby the intake valve 1
4 and the timing valve 24 are both in the open state,
That is, the lower the load, the smaller the crank angle change range (overlap crank angle change range) corresponding to the period in which the intake passage opening/closing means is substantially in the open state. The amount is adjusted.

In the engine in which the timing valve 24 is disposed in the intake passage 20 in this way, the intake air amount is adjusted by the throttle valve disposed in the intake passage in a normal four-stroke gasoline engine, and the intake-compression ratio is adjusted at low load. While each stroke of expansion and exhaust is performed in a state where a PV diagram (a diagram showing the relationship between cylinder internal pressure P and cylinder internal volume ■) as shown in Fig. 7 is obtained, Each stroke of suction-compression-expansion-exhaust under a low load is performed in a state where a PV diagram as shown in FIG. 8 is obtained. That is, first, in the intake stroke (a-b-c), the intake valve 14
and the timing valve 24 are both open (a
-b), the intake air is drawn into the combustion chamber 1o with the cylinder internal pressure P at approximately atmospheric pressure, and then the timing valve 24 is closed and the intake valve 14 is opened during the period (b). -c), the intake air existing in the combustion chamber 10 and in the portion between the intake valve 14 and the timing valve 24 in the intake passage 2° is adiabatically expanded, and the piston 12 is forced to resist its movement. This results in a state where a huge negative pressure is applied. Then, in the first half (c-d) of the subsequent compression stroke (c-d-e), the negative pressure that acted on the piston 12 during the suction stroke acts to promote the movement of the piston 12, and then during the compression stroke (c-d In the latter half (de) of -e), the pressure inside the cylinder (inside the combustion chamber 10) is increased.

In the P-V diagrams of FIGS. 7 and 8, the area of the hatched area in the region where the cylinder internal pressure P is lower than the atmospheric pressure Po is the area corresponding to the pumping loss that occurs during the suction stroke. It will be according to the
When the PV diagram in Figure 8 is obtained, the suction stroke (a
- b - c) During the period (a - b) in which both the intake valve 14 and the timing valve 24 are in the open state, the soot air is applied to the combustion chamber 1o in a state where the cylinder internal pressure P is approximately atmospheric pressure. Inhalation is carried out, almost no pumping loss occurs during this period, and at the end of the intake stroke (c
), the cylinder internal pressure P becomes a relatively large negative pressure, and as a result, at FJI (C-d) before the compression stroke,
Hunting is performed by making the bone compensating for the pumping loss that occurs during the period (b-c) in which the timing valve 24 is in the closed state and the intake valve 14 is in the open state in the intake stroke to be relatively large. The area of the part
This is significantly reduced compared to the case where the PV diagram shown in the figure is obtained. That is, in the engine in which the timing valve 24 is arranged in the intake passage 20 described above, the pumping loss at low load is significantly reduced compared to a normal engine.
As a result, fuel efficiency will improve.

As a specific example of the structure of the intake passage provided with the timing valve as described above, for example, Japanese Patent Laid-Open No. 58-2
As shown in Japanese Patent No. 3245, a main intake passage and a sub-intake passage are provided in the intake passage, a shutter valve is disposed in the main intake passage, and the shutter valve in the main intake passage is bypassed. A rotary valve is placed in the sub-intake passage,
It is known that these shutter valves and rotary valves form the above-mentioned timing valve.

In addition, instead of configuring the intake passage opening/closing means with an intake valve and a timing valve, the intake passage opening/closing means is configured only with the intake valve like in a normal engine, and the period during which the intake valve is in the open state ( It is also conceivable to adjust the intake air amount by changing the crank angle change range (crank angle change range) according to the engine load, and to reduce the pumping loss at low load in the same manner as described above.

(Problems to be Solved by the Invention) However, in an engine in which the period during which the intake passage opening/closing means is in the open state is changed in accordance with the engine load as described above, it is particularly difficult to solve the problem as shown in FIG. p-v of
At low load when the IA diagram is obtained, the cylinder internal pressure P at the start of the compression stroke (C) becomes a relatively large negative pressure, so the effective compression volume in the cylinder becomes small and the effective compression is reduced. Therefore, the cylinder pressure P near the end of the compression stroke (e)
There is a risk that the compression pressure may not be set to a sufficiently high level, resulting in poor ignition performance in the combustion chamber 10.

In view of this, the present invention provides an intake passage opening/closing means that is provided in an intake passage connected to a combustion chamber of an engine and opens and closes the intake passage for each operating cycle, and the intake passage opening/closing means is in an open state. The crank angle change range, which is said to be An object of the present invention is to provide a control device for an engine that can be controlled so as to allow the engine to sag.

(Means for Solving the Problems) In order to achieve the above-mentioned object, an engine control device according to the present invention provides an intake passage opening/closing system that opens and closes an intake passage communicating with a combustion chamber of an engine for each operating cycle of the engine. means and
An opening/closing control means for changing an intake air intake crank angle change range in which the intake passage opening/closing means is substantially open according to the engine load, and an opening/closing control means for increasing the engine compression ratio as the intake air introduction crank angle change range is made small. and a compression ratio adjusting means.

(Function) In the engine control device according to the present invention configured as described above, the intake passage opening/closing means opens and closes the intake air in an open state in each operating cycle of the engine under the control of the control means. It operates so that the crank angle change range becomes smaller as the engine load decreases. This allows the intake air amount in the engine to be adjusted, reducing pumping loss especially when the engine is under low load, and improving fuel efficiency. In addition to this, the compression ratio adjustment means
As the intake air intake crank angle change range becomes smaller, that is, the engine load becomes lower, the compression ratio of the engine becomes larger. Therefore, even when the engine is in a low-load operating state, sufficient compression pressure is obtained within the combustion chamber, and good ignition performance is maintained.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of an engine control device according to the present invention.
It is shown along with the engine to which it was applied.

In FIG. 1, an intake passage 20 communicates with a combustion chamber 10 formed inside a cylinder head 15 and a cylinder block 13 at the side of the engine body through an intake valve 14, and an exhaust valve (not shown) communicates with the combustion chamber 10. The exhaust passages are arranged to communicate with each other. A downstream portion of the intake passage 20 is separated by a partition wall 26 into a main intake passage 20A and a sub-intake passage 20.
For example, when an accelerator pedal 48 (described later) is depressed beyond a certain level, the main intake passage 2OA opens with an opening degree corresponding to the amount of depression of the accelerator pedal 48. A shutter valve 28 is provided. Further, a fuel injection valve 23 is provided in a portion of the main intake passage 20A downstream of the shutter valve 28. On the other hand, the auxiliary intake passage 20B bypasses the above-mentioned shutter valve 28, and is formed to have a smaller passage cross-sectional area than the main intake passage 20A. The sub-intake passage 20B has a crankshaft 3
17 of the crankshaft 32 via the belt 34.
A rotary valve 3 driven to rotate with a rotation speed of 2.
This rotary valve 30 and the shutter valve 28 disposed in the main intake passage 2OA form a timing valve.

The rotary valve 30 has a through hole 30a having a circular cross section formed in its radial direction, and is configured to rotate together with a driven shaft 42 shown in FIG. 2. As shown in FIG. 2, the rotation of a drive shaft 38, the end of which is connected to a pulley 36 on which a belt 34 is mounted, is transmitted to a driven shaft 42 via a rotation adjustment member 40. Helical splines (not shown) are formed at mutually opposing ends of the shaft 38 and the driven shaft 42, respectively, with directions different from each other. A matching protrusion is provided.

Further, a guide rod 4 is provided on the outer peripheral side of the rotation adjustment member 40.
An arm 46 that is guided by the shaft 4 and moves in the axial direction of the drive shaft 38 and the driven shaft 42 engages with each other. When the accelerator pedal 48 is depressed, the arm 46 is pulled by the linkage member 47 and is moved in the direction of arrow U by a distance corresponding to the amount of depression of the accelerator pedal 48 against the elasticity of the spring 51. , the driven shaft 42 is rotated to the lag side relative to the drive shaft 38 by a predetermined rotation angle. As a result, the timing when the rotary valve 30 is opened is determined from the crank angle change range, the effective opening area of the valve is plotted on the vertical axis, and the crank angle is plotted on the horizontal axis. Opening degree change α and rotary valve 30
In FIG. 3, where the opening degree change β of the rotary valve 30 is shown, for example, assume that the opening degree change β of the rotary valve 30 moves from the position shown by the solid line to the position shown by the dashed-dotted line as shown by the arrow V. It is made to change as it becomes.

Based on this configuration, the timing valve formed by the shutter valve 28 and the rotary valve 30 is closed at a time prior to the intake valve 14 in each operating cycle of the engine, and the timing valve formed by the shutter valve 28 and the rotary valve 30 is closed at a time prior to the intake valve 14. The overlap crank angle change range in which both the timing valve formed by the rotary valve 28 and the rotary valve 30 are open, that is, the intake intake crank angle change range is controlled to be smaller as the engine load is lower. Thus, the amount of intake air in the combustion chamber 10 is adjusted. As a result, as described above with reference to FIG. 8, the pumping loss during the intake stroke is reduced, especially when the engine is in a low load operating condition. Note that in this example, the intake valve 14. The shutter valve 28 and the rotary valve 30 constitute an intake passage opening/closing means.

On the other hand, the cylinder head 15 that forms the upper part of the combustion chamber 10 described above is equipped with a valve mechanism (not shown) that opens and closes the intake valve 14 and the exhaust valve at predetermined timing, as well as a valve mechanism (not shown) that changes the volume of the combustion chamber 10. Compression ratio adjusting means 50 is provided to change the compression ratio by changing the compression ratio. The compression ratio adjusting means 50 has a piston 54 inserted into a bore 52 formed in the cylinder head 15 and opening into the combustion chamber 10. , is moved within the bore 52.

The first oil chamber 56a and the second oil chamber 56 of the power cylinder 56
b, first and second oil supply and drainage passages 57 and 59, respectively.
The first and second oil supply and discharge passages 57 and 59 communicate with a hydraulic oil supply passage 61 and a hydraulic oil discharge passage 62 via a switching valve 60, respectively. The switching valve 60 has three land portions 63a, 63b and 6.
3c is formed on the spool 63, and the land portion 63a
The communication state between the first oil supply and drainage passage 57 and the hydraulic oil discharge passage 62 is determined by the land portion 63b, the communication state between the second oil supply and discharge passage 59 and the hydraulic oil discharge passage 62 is determined by the land portion 63b, and the land portion 63
In c, the communication state between the first and second oil supply/drainage passages 57 and 59 and the hydraulic oil supply passage 61 is changed by changing the effective passage cross-sectional area in each part, respectively, and the first oil chamber 5 is changed.
6a and the second oil chamber 56b.

The spool 63 of the switching valve 60 is connected to the drive rod 65a of the actuator 65.
is caused to move in its axial direction. When the spool 63 is pulled by the actuator 65 and moved upward in FIG. At the same time, the second oil chamber 5
Hydraulic oil flows from 6b to oil reservoir 67 via hydraulic oil discharge passage 62.
will be returned to. This causes the power piston 58 to move upward in FIG. 1 along with the piston 54,
As a result, the volume of the combustion chamber IO is substantially expanded. By substantially expanding the volume of the combustion chamber 10 in this way, the compression ratio of the engine is reduced. On the other hand, when the spool 63 is pushed by the actuator 65 from this state and is moved downward G in FIG. 1, the power piston 58 is moved downward in FIG. 1 together with the piston 54, and as a result , the volume of the combustion chamber 10 is substantially reduced.

By substantially reducing the volume of the combustion chamber 10 in this way, the compression ratio of the engine is increased.

In this example, the operation of the actuator 65 is as follows:
The above-mentioned intake valve 14, shutter valve 28, and rotary valve 3
As the intake intake crank angle change range in which both the timing valve formed by 0 and the timing valve are in the open state becomes smaller, that is,
This is done by increasing the compression ratio of the engine as the engine load decreases. Therefore, a control unit 100 is provided to control the operation of the actuator 65.

The control unit 100 includes the amount of depression of the accelerator pedal 48 detected by the amount sensor 70 of the accelerator pedal;
Therefore, the detection signal S corresponds to the engine load.
a, the position of the power piston 58 detected by the position sensor 72, and therefore a detection signal sb corresponding to the position of the piston 54. The control unit 100 controls, based on the detection signal Sa and the detection signal sb, the compression ratio of the engine to be changed as shown by a curve W in FIG. 5 with respect to the amount of depression of the accelerator pedal 48. A signal Cp is formed and supplied to the actuator 65.

As a result, the smaller the amount of depression of the accelerator pedal 48, and hence the smaller the engine load, that is, the smaller the intake intake crank angle change range, the larger the engine compression ratio becomes. become.

In the control unit 100, an accelerator pedal 48 as shown by the curve W in FIG.
Information on the position that the piston 54 should take in order to realize a change in the compression ratio of the engine with respect to the amount of depression is stored in a built-in memory. And the control unit 100
is the detection signal S obtained from the accelerator depression amount sensor 70
The position that the piston 54 should take (hereinafter referred to as the target position) is read based on the position a, and the read target position and the detection signal s obtained from the position sensor 72 are
When b occurs, the control signal C is compared with the actual position of the piston 54 (hereinafter referred to as the actual position) to calculate the difference between the target position and the actual position, and is supplied to the actuator 65.
The level of p is set according to this difference. Thereby,
The actuator 65 extends or retracts the drive rod 65a depending on the level of the control signal Cp, and adjusts the amount of hydraulic oil supplied to and discharged from the first oil chamber 56a and the second oil chamber 56b. As a result, piston 5
4 is moved to the target position.

The control unit 100 that performs the above-described control is configured using, for example, a microcomputer, and an example of a program executed by the microcomputer in such a case will be described with reference to the flowchart shown in FIG. explain.

In this program, after starting, process 10
1, the detection signal S obtained from the accelerator depression amount sensor 70
a and the detection signal sb obtained from the position sensor 72, and in the subsequent process 102, the detection signal Sa is detected.
Read the target position of 4 from the memory. Next process 10
3, the difference between the target position read out in process 102 and the actual position of the piston 54 obtained by the detection signal sb obtained from the position sensor 72 is calculated, and step 1
Proceed to 04. In process 104, a control signal Cp of a level corresponding to the difference between the target position and actual position of the piston 54 calculated in process 103 is formed, and this is supplied to the actuator 65.

This causes the actuator 65 to move toward its drive rod 65.
By protruding or retracting a, the spool 63 is moved by a distance corresponding to the level of the control signal Cp. As a result, the amount of hydraulic oil supplied to and discharged from the first oil chamber 56a and the second oil chamber 56b is adjusted, and the piston 54 is moved to the target position. The smaller the amount of depression of the 7-cell pedal 48, the higher the compression ratio of the engine. Therefore, even when the engine load is small and the intake intake crank angle variation range is small, sufficient compression pressure can be obtained in the combustion chamber 1o, and ignitability can be maintained well.

In the above example, the piston 54 is inserted into the bore 52 provided in the cylinder head 15 and opens into the combustion chamber 10 as the compression ratio adjusting means.
Although the compression ratio adjusting means is of the type that changes the volume of the combustion chamber IO by being moved up and down, other types of compression ratio adjustment means, such as the cylinder block 13
By changing the connection position of the piston and connecting rod inside,
A type that changes the volume of the combustion chamber 10 may also be used.

Further, in the above example, the intake valve 14. Although the intake passage opening/closing means is composed of the shutter valve 28 and the rotary valve 30, the intake passage opening/closing means may be composed of the intake valve and the rotary valve, or only the intake valve, as described above. Even in such a case, the same effects as described above can be obtained.

(Effects of the Invention) As is clear from the above description, according to the engine control device according to the present invention, a timing valve is arranged in the intake passage,
This timing valve is closed prior to the intake valve in each engine operating cycle, and the overramp crank angle change range in which both the intake valve and timing valve are open is smaller as the engine load is lower. Since the amount of intake air in the combustion chamber of the engine is adjusted, pumping losses during the intake stroke are reduced, especially when the engine is operating at low load, resulting in improved fuel efficiency. be done.

In addition to this, the compression ratio adjustment means increases the compression ratio of the engine as the range of change in the intake crank angle in which the intake passage opening/closing means is opened is made smaller, so that the engine has a low load. Even when the engine is in operation, sufficient compression pressure is obtained within the combustion chamber and good ignitability is maintained.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an engine control device according to the present invention together with an engine to which it is applied, FIG. 2 is a partial configuration diagram of the example shown in FIG. 1, and FIG. FIG. 4 is a flowchart showing an example of a program executed by a microcomputer when a microcomputer is used as the control unit in the example shown in FIG. Fig. 5 is a characteristic diagram used to explain the operation of the example shown in Fig. 1, Fig. 6 is a schematic configuration diagram showing an engine in which a timing valve is arranged in the intake passage, and Fig. 7 is a diagram of a typical four-stroke engine. PV Diagram FIG. 8 is a P-■ diagram of an engine in which a timing valve is arranged in the intake passage. In the figure, 14 is an intake valve, 20 is an intake passage, 28 is a shutter valve, 30 is a rotary valve, 4o is a rotation adjustment member, 50 is a compression ratio adjustment means, 7o is an accelerator depression amount sensor, 100
is the control unit. Axel Vedano drawing I Volume (V) Volume (V)

Claims (1)

[Claims] An intake passage opening/closing means for opening/closing an intake passage communicating with a combustion chamber of the engine for each operating cycle of the engine, and an intake passage opening/closing means for opening/closing an intake passage communicating with a combustion chamber of the engine, and an intake intake crank angle change range in which the intake passage opening/closing means is substantially open under the load of the engine. An engine control device comprising: opening/closing control means for changing the compression ratio according to the change in the intake air intake crank angle; and compression ratio adjusting means for increasing the compression ratio of the engine as the intake air introduction crank angle change range is made smaller.