JP2008095610A - Valve timing control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep driving performance excellent when valve timing of an intake valve and exhaust valve is simultaneously changed. <P>SOLUTION: Crank angles Ai and Ae from a current intake valve opening time (IVO) and an exhaust valve closing time (EVC) to the intake top dead center are calculated when operation is judged to be a deceleration, valve timing control is started from the valve having a larger crank angle of the crank angles Ai and Ae when the IVO is after the compressed top dead center and the EVC is before the intake top dead center, the valve timing control of the exhaust valve is carried out in advance when both IVO and EVC are after the intake top dead center, and the valve timing control of the intake valve is carried out in advance when both IVO and EVC are before intake top dead center. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to an apparatus for controlling the valve timing of an intake valve and an exhaust valve of an internal combustion engine, and more particularly to control for changing the valve timing while maintaining good operability.

In Patent Document 1, when a deceleration operation state is detected, an intake valve or an exhaust valve is driven by driving a variable valve timing mechanism so that an overlap amount between the intake valve and the exhaust valve is reduced to reduce an internal EGR amount. It is disclosed that at least one of the above is changed.
Utility Kaihei 5-66237

In an internal combustion engine having both a variable valve timing mechanism for an intake valve and a variable valve timing mechanism for an exhaust valve, when changing both the valve timings of the intake valve and the exhaust valve, the two variable valve timing mechanisms are simultaneously used. When driven, a large driving force is required. In particular, in the hydraulic variable valve timing mechanism, it is necessary to increase the oil pump capacity so that the hydraulic pressure does not become insufficient. However, the expansion of the capacity leads to an increase in friction and deteriorates the fuel consumption.

Therefore, after the variable valve timing mechanism of one valve is driven first to control the valve timing of this valve to the target value, the variable valve timing mechanism of the other valve is driven later to control to the target value Is realistic. Here, if the drive order is set regardless of the operation state, the transient performance during the change may be deteriorated. For example, when performing control to reduce the valve overlap amount when detecting a deceleration operation state as described in Patent Document 1, there is a request to reduce the internal EGR as quickly as possible, but this request may be satisfied depending on the driving order. There was nothing.

The present invention has been made paying attention to such a conventional problem, and in an internal combustion engine valve timing control device separately provided with variable valve timing mechanisms for an intake valve and an exhaust valve, an intake valve and an exhaust valve are provided. By controlling the valve timings in an appropriate order, the valve timing can be changed while maintaining good operability.

For this reason, the invention according to claim 1
In a valve timing control device for an internal combustion engine comprising a variable valve timing mechanism for an intake valve and a variable valve timing mechanism for an exhaust valve,
When changing the valve timing of both the intake and exhaust valves, the valve timing control sequence for the intake and exhaust valves is determined based on the intake valve opening timing and exhaust valve closing timing before the change, and each variable valve timing is determined. The mechanism is driven according to a determined control sequence.

In this way, by driving the variable valve timing mechanism one by one, while avoiding an increase in the size of the drive source, the control timing of the valve timing is based on the intake valve opening timing and the exhaust valve closing timing before the change. By determining, when reducing the valve overlap amount and reducing the internal EGR amount, such as during sudden deceleration, the control order is determined so that the control can be performed first, starting from the one that can greatly reduce the initial internal EGR amount. For example, the valve timing can be changed while maintaining good operability.

FIG. 1 is a system diagram showing the overall configuration of an embodiment of the present invention.
The intake passage 2 of the engine 1 is provided with an air flow meter 3 for detecting the intake air amount.
The intake air amount is adjusted by the throttle valve 4.
Each cylinder of the engine 1 is provided with a fuel injection valve 7 that injects fuel into the combustion chamber 6, and an ignition plug 8 that performs spark ignition within the combustion chamber 6, and the air taken in through the intake valve 9 In contrast, fuel is injected from the fuel injection valve 7 to form an air-fuel mixture, which is compressed in the combustion chamber 6 and ignited by spark ignition by the spark plug 8.

Exhaust gas from the engine 1 is discharged from the combustion chamber 6 to the exhaust passage 11 via the exhaust valve 10.
It is discharged into the atmosphere through an exhaust purification catalyst and a muffler (not shown).
The intake valve 9 and the exhaust valve 10 are driven to open and close by cams provided on the intake valve side camshaft 12 and the exhaust valve side camshaft 13, respectively.
The intake valve side camshaft 12 and the exhaust valve side camshaft 13 are of hydraulic drive type that advance and retard the valve timing (opening and closing timing) of the intake and exhaust valves by changing the rotational phase of the camshaft with respect to the crankshaft. Variable valve timing mechanisms (hereinafter referred to as VTC mechanisms) 14A and 14B are provided.

Here, the operation of the throttle valve 4, the fuel injection valve 7 and the spark plug 8 is controlled by an ECU (electronic control circuit) 21. The ECU 21 includes a crank angle sensor 15, camshaft sensors 16A and 16B, a water temperature sensor. 17. A signal from the air flow meter 3 or the like is input.
The ECU 21 also sets a target rotational phase (advance value) with respect to the crankshafts of the intake side camshaft 12 and the exhaust side camshaft 13 based on information such as engine load (fuel injection amount), rotational speed Ne, and coolant temperature Tw. (Or retard angle value), that is, the target valve timings of the intake valve 9 and the exhaust valve 10 are respectively determined, while the crank angle is determined based on the crank angle sensor 15 and the detection signals from the intake-side and exhaust-side camshaft sensors 16A, 16B. The rotational phases of the intake camshaft 12 and the exhaust camshaft 13 relative to the shaft, that is, the actual valve timings of the intake valve 9 and the exhaust valve 10 are detected, and control is performed so that the actual valve timing becomes the target valve timing.

As shown in FIG. 2, the hydraulic drive type VTC mechanism 14 includes a cylindrical housing 5 of a cam sprocket that is rotationally driven via a timing chain by a crankshaft (not shown).
1, a rotating member 52 fixed to the end of the cam shaft (12, 13) and rotatably accommodated in the housing 51, and a hydraulic pressure for rotating the rotating member 52 relative to the housing 51. Circuit 53.

On the inner peripheral surface of the housing 51, a trapezoidal shape in cross section is provided, and four partition wall portions 51A provided along the axial direction of the housing 51 are projected at 90 ° intervals.
The rotating member 52 is fixed to the front end portion of the cam shaft, and four vanes 52B are provided on the outer peripheral surface of the annular base portion 52A at intervals of 90 °, so that each partition wall portion 51A of the housing 51 is provided.
The advance side hydraulic chamber 61 and the retard side hydraulic chamber 62 are provided between the both sides of the vane 52B and the both side surfaces of each partition wall 51A. Constitute.

The hydraulic circuit 53 includes a first hydraulic passage 81 that supplies and discharges hydraulic pressure to the advance side hydraulic chamber 61;
There are two systems of hydraulic passages, a second hydraulic passage 82 that supplies and discharges hydraulic pressure to and from the retard side hydraulic chamber 62. The hydraulic passages 81 and 82 include a supply passage 83 and drain passages 84A and 84B. Are connected via an electromagnetic switching valve 91 for path switching. The supply passage 83 is connected to an engine-driven oil pump that pumps oil in the oil pan, while a drain passage 84A,
The downstream end of 84B is connected to the oil pan.

The electromagnetic switching valve 91 is configured such that an internal spool valve body 92 relatively switches and controls the hydraulic passages 81 and 82, the supply passage 83, and the drain passages 84A and 84B.
The ECU 21 controls an energization amount for the solenoid 93 of the electromagnetic switching valve 91.
For example, when the energization amount to the solenoid 93 is increased, the hydraulic oil is supplied into the advance hydraulic chamber 61 through the first hydraulic passage 81 as shown in FIG. Hydraulic chamber 62
The hydraulic fluid inside is discharged to the oil pan through the second hydraulic passage 82 and the drain passage 84A, and the retard side hydraulic chamber 62 becomes low pressure.

For this reason, the rotating member 52 rotates to the advance side through the vane 52B. In the case of the variable valve timing mechanism 14 on the intake valve 9 side, the opening timing of the intake valve 9 is advanced (advanced).
The overlap with the exhaust valve 10 is increased.
On the other hand, when the energization amount to the solenoid 93 is decreased, the hydraulic oil pumped from the oil pump is supplied to the retard side hydraulic chamber 62 through the second hydraulic passage 82 as shown in FIG. At the same time, the hydraulic oil in the advance side hydraulic chamber 61 passes through the first hydraulic passage 81 and is discharged from the drain passage 84B into the oil pan.

Accordingly, the internal pressure of the retard side hydraulic chamber 62 is high and the internal pressure of the advance side hydraulic chamber 61 is low, and the rotating member 52 rotates to the retard side via the vane 52B. In the case of the variable valve timing mechanism 14 on the intake valve 9 side, the opening timing of the intake valve 9 is delayed (retarded), and the overlap with the exhaust valve 10 is reduced.
Similarly, in the case of the variable valve timing mechanism on the exhaust valve 10 side, by supplying hydraulic pressure into the retarded hydraulic chamber 62, the closing timing of the exhaust valve 10 is retarded and the overlap with the intake valve 9 is large. Thus, by supplying the hydraulic pressure into the advance side hydraulic chamber 61, the closing timing of the exhaust valve 10 is advanced and the overlap with the intake valve 9 is reduced.

As described above, the variable valve timing mechanism 14A for the intake valve 9 and the exhaust valve 10
In the valve timing control device provided with the variable valve timing mechanism 14B for use, when a request for changing both the valve timing of the intake valve 9 and the valve timing of the exhaust valve 10 occurs, the opening of the intake valve 9 before the change is opened. Based on the timing and the closing timing of the exhaust valve 10, a change order between the valve timing of the intake valve 9 and the valve timing of the exhaust valve 10 is determined, and the valve timing is controlled according to the change order.

FIG. 3 shows a flow of the valve timing control during the deceleration operation.
In step S1, it is determined from the throttle valve opening or the like whether or not the vehicle has been decelerated. During deceleration operation, the intake valve 9 is opened (hereinafter referred to as IVO) and the exhaust valve 10 is closed so that the valve overlap amount is reduced to reduce the internal EGR amount in order to ensure stable combustibility. (Hereinafter referred to as EVC) is set so that both are close to the intake top dead center.

When it is determined in step S1 that the vehicle is decelerating, the process proceeds to step S2 where the camshaft sensor 16
Based on the detection signals from A and 16B, IVO and EVC are read.
In step S3, the crank angle Ai from the IVO to the intake top dead center and the crank angle Ae from the intake top dead center to the EVC are calculated, and the two values are compared. Note that the crank angle position increases according to the amount of rotation (for example, as shown in FIGS. 4 to 6, the intake top dead center is 0, the intake bottom dead center is 180 °, the intake top dead center is 360 °, the exhaust bottom At the dead point (540 °), calculation is performed as follows.

Ai = Crank angle position of intake top dead center−Crank angle position of IVO Ae = Crank angle position of EVC−Crank angle position of intake top dead center In step S4, Ai, Ae> 0, that is, before change It is determined whether the IVO is before the intake top dead center and the EVC is after the intake top dead center.
If it is determined that Ai, Ae> 0, the process proceeds to step S5 to determine whether Ai> Ae.

When Ai> Ae, the initial valve overlap amount decrease is larger when IVO is closer to the target intake top dead center than when EVC is closer to the target intake top dead center. can do.
That is, it is possible to reduce the valve overlap amount more quickly by increasing the initial operation amount, especially by controlling the IVO farther away from the intake top dead center than the EVC to approach the intake top dead center first. In addition, when the IVO is controlled to the intake top dead center and the valve overlap amount has already been reduced by more than half of the first, the control is switched to the EVC control, and the switching timing with delay may be shifted to the second half. As a result, the initial reduction amount of the valve overlap can be increased.

If the valve overlap amount is greatly reduced in the initial stage, the internal EGR amount can be quickly reduced in the process of shifting to the idle state and the intake air amount is reduced, so that stable combustibility can be maintained.
Therefore, when it is determined in step S5 that Ai> Ae, the process proceeds to step S6, and it is determined that the valve timing control of the intake valve 9 is performed before the valve timing control of the exhaust valve 10.

If the determination in step S5 is no, the process proceeds to step S7 to determine whether Ae> Ai.
When it is determined that Ae> Ai, for the same reason as described above, the valve overlap amount is reduced more quickly when the EVC is first brought closer to the intake top dead center than when the IVO is brought closer to the intake top dead center. Since it is possible to proceed to step S8, the valve timing control of the exhaust valve 10 is performed.
It is determined that the control is performed prior to the valve timing control of the intake valve 9.

If the determination in step S7 is NO, that is, if it is determined that Ai = Ae, basically, the valve timing of either the intake valve 9 or the exhaust valve 10 may be controlled first. In step S9, Decide to control in the preset order.
If there is a difference in responsiveness of valve timing control due to different actuators,
It is better to set the control so that the one with good responsiveness is first, and in this case, even if the sizes of Ai and Ae are different, the control order should be determined in consideration of the responsiveness. . For example, the control order may be determined by comparing values obtained by multiplying Ai and Ae by a responsive correction coefficient (larger as the responsiveness is higher).

Further, when the determination in step S4 is NO, the process proceeds to step S10, and Ai ≦ 0, Ae ≧
It is determined whether it is 0 (excluding Ai = Ae = 0), that is, whether IVO and EVC are after the intake top dead center. If YES is determined, the process proceeds to step S8 and the exhaust valve 10 is It is determined that the valve timing control is performed prior to the valve timing control of the intake valve 9.

In other words, the valve overlap amount is reduced by first bringing the EVC closer to the intake top dead center, and the valve overlap amount is reduced to 0 by setting the IVO closer to the intake top dead center. .
In this way, the valve overlap amount does not increase during the transition to the idle state, and good combustion stability can be maintained. When the order is reversed, the valve overlap amount is increased by the control that brings the previous IVO closer to the intake top dead center, and then the valve overlap amount is decreased by the control that brings the subsequent EVC closer to the intake top dead center. Therefore, the combustibility is deteriorated when the valve overlap amount is increased.

If there are only three combinations of valve timings before deceleration, the determination in step S10 may be omitted and the process may proceed to step S8.
Further, when there is a combination of valve timings, the following processing is performed.
When the determination in step S10 is NO, the process proceeds to step S11 and Ai ≧ 0, Ae ≦ 0 (
Ai = Ae = 0), that is, whether IVO and EVC are before the intake top dead center, and if YES is determined, the process proceeds to step S6 and the valve timing of the intake valve 9 is determined. It is determined that the control is performed before the valve timing control of the exhaust valve 10.

That is, the valve overlap amount is reduced by reducing the valve overlap amount from 0 to a negative overlap state by first bringing IVO closer to the intake top dead center, and then the valve overlap amount is set to 0 by bringing EVC closer to the intake top dead center. .
In this way, the valve overlap amount does not increase during the transition to the idle state, and good combustion stability can be maintained. If the order is reversed, the valve overlap amount is increased by controlling the previous EVC closer to the intake top dead center, and then the valve overlap amount is decreased by controlling the subsequent IVO closer to the intake top dead center. Therefore, the combustibility is deteriorated when the valve overlap amount is increased.

If the determination in step S10 is NO, Ai ≦ 0, Ae ≦ 0, that is, IVO is after the intake top dead center and EVC is before the intake top dead center, and in this state, no valve overlap occurs. There is no need to worry about deterioration in combustibility, and either of them may be controlled first, so the process proceeds to step S9, and it is determined to control in a preset order.
When only one of the two states of IVO and EVC before deceleration determined after step S10 is controlled, when the determination of step S10 is NO, the valve What is necessary is just to perform the said control corresponding to a timing state.

In step S12, the valve timing control of the intake valve 9 and the exhaust valve 10 is performed according to the variable valve timing mechanism according to the control sequence of the valve timing determined according to the state of IVO and EVC before deceleration as described above. This is performed by driving 14A and 14B. Specifically, after detecting that the IVO or EVC is controlled to the intake top dead center by the valve timing control performed earlier, the subsequent valve timing control is performed.

4 shows the control in step S6, FIG. 5 shows the control in step S8, and FIG.
9 shows the state of the control at 9 (in particular, the case of | Ai | = | Ae |).
According to the above embodiment, the variable valve timing mechanism 1 for the intake valve 9 and the exhaust valve 10 is used.
By driving each of 4A and 14B one by one, enlargement of the drive source such as expansion of the oil pump capacity can be avoided, and the internal EGR amount can be quickly reduced at the time of switching to deceleration so that the operability during switching transition (stable Can be maintained satisfactorily.

In the above embodiment, the case of switching to deceleration is shown, but conversely, when the operating state switches in the direction in which the internal EGR increases, for example, the IVO before switching and the target IVO after switching operation Deviation (crank angle), EVC before switching and target EV after switching operation
By comparing the deviation (crank angle) with C and controlling the valve timing from the larger one first, the internal EGR amount can be increased quickly from the beginning, and the operability during switching transitions is maintained well. can do.

Further, the variable valve timing mechanism is not limited to the hydraulic drive type as in the embodiment, and can be applied to an electric type.

1 is a system diagram showing the overall configuration of an embodiment of the present invention. Sectional drawing which shows the valve timing control state by the variable valve timing mechanism in embodiment same as the above. The flowchart which shows the valve timing control at the time of the driving | operation to the deceleration in embodiment same as the above. The time chart which shows the mode of a change of valve timing when performing the valve timing control of exhaust valve timing after performing the valve timing of an intake valve first. The time chart which shows the mode of a change of valve timing when valve timing of an exhaust valve is performed first and valve timing control of intake valve timing is performed later. FIG. 5 is a time chart showing a change in valve timing when the valve timing of the intake valve is performed first from the initial state different from that in FIG. 4 and the valve timing control of the exhaust valve timing is performed later.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine 9 ... Intake valve 10 ... Exhaust valve 12 ... Intake valve side cam shaft 13 ... Exhaust valve side cam shaft 14A ... Variable valve timing mechanism for intake valves 14B ... Variable valve timing mechanism for exhaust valves 15 ... Crank angle sensor 16A, 16B ... camshaft sensor 21 ... engine control circuit (ECU)

Claims (6)

In a valve timing control device for an internal combustion engine comprising a variable valve timing mechanism for an intake valve and a variable valve timing mechanism for an exhaust valve,
When changing the valve timing of both the intake and exhaust valves, the valve timing control sequence for the intake and exhaust valves is determined based on the intake valve opening timing and exhaust valve closing timing before the change, and each variable valve timing is determined. A valve timing control device for an internal combustion engine, wherein the mechanism is driven in accordance with a determined control sequence. If the valve overlap amount between the intake valve and exhaust valve after the valve timing change is less than the valve overlap amount before the change, the valve of the valve that can greatly reduce the valve overlap amount at the initial stage of control 2. The valve timing control apparatus for an internal combustion engine according to claim 1, wherein the control order is determined so as to control the timing first. When the target intake valve opening timing and target exhaust valve closing timing at the time of engine deceleration after the valve timing change are both the intake top dead center, the intake valve open timing before the valve timing change is after the intake top dead center, and the exhaust valve close The control order is determined so that the valve timing of the valve having the larger crank angle to the intake top dead center is controlled first when the timing is before the intake top dead center. The valve timing control device for an internal combustion engine. When both the target intake valve open timing and target exhaust valve close timing during engine deceleration after the valve timing change are taken as the intake top dead center, both the intake valve open timing and exhaust valve close timing before the valve timing change are the intake top dead center. When it is later, the valve timing of the exhaust valve is controlled first, and when both the intake valve opening timing and the exhaust valve closing timing before the valve timing change are before the intake top dead center, the intake valve timing is advanced. 4. The valve timing control apparatus for an internal combustion engine according to claim 2, wherein the control order is determined so as to control the engine. When the valve overlap amount between the intake valve and exhaust valve after the valve timing change increases relative to the valve overlap amount before the change, the valve of the valve that can greatly increase the valve overlap amount at the initial stage of control The valve timing control device for an internal combustion engine according to any one of claims 1 to 4, wherein the control order is determined so as to control the timing first. 6. The valve timing control device for an internal combustion engine according to claim 1, wherein the variable valve timing mechanisms for the intake valve and the exhaust valve are hydraulically driven.

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