JPH0535256B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine control device.

[Prior Art] In the latest vehicle engines, from the perspective of improving engine drivability, various combustion state control devices are used to detect unstable combustion states of the engine using roughness sensors and control the combustion state of the engine. Various types of so-called roughness control have been carried out to reduce roughness such as engine vibration caused by the unstable combustion state.
As an example, there is a conventional system in which the air-fuel ratio of the air-fuel mixture is corrected and controlled in accordance with the output of a roughness sensor when roughness occurs, as shown in Japanese Utility Model Application Publication No. 57-31552.

In addition, various proposals have been made to operate the engine efficiently by variably controlling the opening and closing timing of intake and exhaust ports in vehicle engines according to the operating state of the engine. The valve lift amount of the intake and exhaust valves is controlled as shown in Japanese Patent Publication No. 56-150806, or the valve drive cam is brought into contact with the tappet of the intake and exhaust valves as shown in Japanese Patent Application Laid-open No. 59-65509. There are some that control the timing and change the opening/closing timing and valve opening angle of the intake and exhaust valves.

Even in engines equipped with such intake and exhaust port opening/closing timing control devices, if the roughness control described above is performed, it is expected that drivability can be further improved.Moreover, in this case,
Since the combustion state of the engine changes by changing the opening/closing timing of the intake and exhaust ports, it is considered that the opening/closing timing should be controlled in accordance with the output of the roughness sensor.

[Purpose of the invention]

In view of the above, it is an object of the present invention to provide an engine control device that can control the opening/closing timing of intake and exhaust ports with higher precision.

[Structure of the invention]

Now, considering how to control the roughness of the opening/closing timing of the intake and exhaust ports, it is sufficient to control the opening/closing timing or valve opening angle of the intake and exhaust valves in a direction that suppresses the roughness. The direction of control varies depending on the engine requirements, and it is difficult to uniformly determine this direction.

However, when looking at the opening/closing timing of the intake and exhaust valves at low rotation speeds and low loads, by making the exhaust valve close timing earlier and the intake valve opening timing later, the blowback of exhaust gas is reduced and This reduces residual gas and improves combustion stability. Also, looking at the valve opening angle at low speeds, by reducing the valve opening angles of both the intake and exhaust valves, the overlap between the intake and exhaust valves becomes smaller, and as in the case above, the blowback of exhaust gas is reduced. In any case, at low rotation speeds and low loads, if the overlap between the intake and exhaust ports is reduced, combustion stability can be obtained and roughness can be suppressed. .

Therefore, the present invention provides an engine control device that variably controls the opening/closing timing of the intake and exhaust ports according to the engine operating condition, so that the overlap between the intake and exhaust ports can be reduced when roughness occurs in the engine at low rotation speeds and low loads. The opening/closing timing is corrected accordingly.

That is, the present invention, as shown in the functional block diagram of FIG. The timing change means 50 is controlled according to the operating state, and at this time, the roughness sensor (vibration detection means) detects the roughness (vibration) of the engine, the rotation speed detection means 71 detects the engine rotation speed, and the load detection means 71 detects the engine rotation speed. The means 72 detects the load state of the engine, and the correcting means 52 receives the outputs of the roughness sensor 52, the rotation speed detecting means 71, and the load detecting means 73, and corrects the overlap between the intake and exhaust ports when roughness occurs, at least at low rotation speeds and low loads. The control of the timing control means 51 is corrected in the direction of decreasing the timing.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIGS. 2 and 3 show an engine control device according to an embodiment of the present invention. In the figure, 1 is an engine, a throttle valve 3 is provided in the middle of an intake passage 2 of the engine 1, an air flow meter 4 is provided in the intake passage 2 upstream of the throttle valve 3, and an air flow meter 4 is provided in the intake passage 2 on the upstream side of the throttle valve 3. The upstream end of the intake passage 2 reaches an air cleaner 5, and a fuel injection valve 6 is provided near the downstream end of the intake passage 2. Further, a catalyst 8 for purifying exhaust gas is interposed in the exhaust passage 7 of the engine 1.

The engine 1 is also provided with an idle rotation control mechanism 9 that controls the idle rotation speed. In this control mechanism 9, a bypass passage 10 is formed in the intake passage 2 by bypassing the throttle valve 3, and a control valve 11 for controlling the amount of air flowing into the passage 10 is interposed in the middle of the bypass passage 10. ing.

In addition, part of the exhaust gas is transferred to engine 1 using EGR.
An EGR device 12 is provided that returns gas to the intake system. In this EGR device 12, one end of the EGR passage 13 is connected to the exhaust passage 7, the other end of the EGR passage 13 is connected to the intake passage 2, and the EGR
An EGR valve 14 is installed in the middle of the passage 13.
Negative pressure or positive pressure is introduced into the EGR valve 14.
A solenoid 15 is provided to open and close the EGR valve 14.

And engine 1 has its intake and exhaust ports 2
Suction and exhaust valves 16 and 17 that open and close a and 7a are provided, and camshafts 18 and 1 are attached to the suction and exhaust valves 16 and 17.
9. Tappet 20, 21 and valve spring 2
Valve operating devices 24 and 25 are provided. In addition, the intake and exhaust valves 16 and 17 have timing adjustment devices 26 for adjusting their opening and closing timings.
is provided. This timing adjustment device 26
, the above-mentioned tappet 2 is attached to the rotating bodies 27 and 28.
0, 21 are slidably housed, and the rotating bodies 27,
28 is rotatably provided coaxially with the camshafts 18 and 19, and is configured to be rotated by an actuator 29 in mutually opposite directions.

In the figure, 30 is a distributor, 31 is an ignition coil, 32 is a key switch, 3
3 is a starter, 34 is a negative pressure sensor that detects the intake negative pressure downstream of the throttle, 35 is a throttle opening sensor that detects the opening of the throttle valve 3, and 36 is a rotation speed that detects the engine speed from the engine crank angle. 37 is a water temperature sensor that detects the engine cooling water temperature; 38 is a shift position sensor that detects the shift position of the automatic transmission; 39 is an exhaust sensor that detects the oxygen concentration in exhaust gas; 40 is a catalyst 8;
41 is the EGR catalyst temperature sensor that detects the temperature of
The position sensor 42 of the valve 14 is a vibration sensor serving as a roughness sensor that detects engine vibration, which is a parameter of the roughness state of the engine.

Also, 43 is interface 44, CPU 45
The engine control unit is composed of a memory 46 and a memory 46, and the memory 46 stores arithmetic processing programs for the CPU 45 (see FIG. 3) and the like. Further, the CPU 45 generates a high voltage in the ignition coil 31 according to the rotation of the engine, thereby controlling the ignition timing, and
EGR device 12 depending on the engine operating condition.
The EGR valve 14 is opened and closed to perform EGR control, and the idle rotation control mechanism 9 operates according to the engine cooling water temperature, cooler load, electrical load, etc.
The control valve 11 is opened and closed to control the idle speed, and the basic fuel injection amount corresponding to the engine speed and intake air amount is corrected according to the output of the exhaust sensor 39, and this is used as a fuel injection pulse to inject the fuel. In addition to the injection valve 6, this also performs air-fuel ratio control in which the air-fuel ratio of the air-fuel mixture is feedback-controlled to a set value.

Then, the CPU 45 calculates the opening/closing timing of the intake and exhaust valves 16 and 17 according to the engine speed and the throttle opening, which is a parameter of the engine load, and applies the timing to the actuator 29 of the timing adjustment device 26 for the intake and exhaust valves. While controlling the opening/closing timing of the valves 16 and 17, the vibration sensor 42
When roughness occurs, the intake and exhaust valves 1
Roughness control is performed in which the opening/closing timing is corrected so that the overlap between 6 and 17 is large at low rotations and high loads, and small at other times.

In the above configuration, the timing adjusting device 26 serves as the timing changing means 50 shown in FIG. 1, and the CPU 45 serves as the timing controlling means 51 and the correcting means 53 shown in FIG.
The rotation speed sensor 36 and the throttle opening sensor 35 function as the rotation speed detection means 71 and the load detection means 72, respectively.

Next, the operation will be explained using FIGS. 3 to 5. Here, Fig. 3 shows a flowchart of the arithmetic processing for timing control of the CPU 45, Fig. 4 shows the opening/closing timing of the intake and exhaust valves 16 and 17, and Fig. 5 shows the engine speed and load when roughness occurs. Suction and exhaust valves 16 and 17 as parameters
indicates the direction of overlap correction.

First, the opening/closing timing control and roughness control of the intake and exhaust valves 16 and 17 will be explained. When the engine starts, the CPU 45 initializes the system (step 55) and then determines whether the engine is running (step 56).
The outputs of the rotation speed sensor 36 and the throttle opening sensor 35, which are input information, are read (step 57).
After calculating the opening/closing timing Ti according to the engine speed and the load indicated by the throttle opening (step 58), and determining whether the engine is accelerating or decelerating and whether roughness has occurred (steps 59 and 60). , the opening/closing timing Ti obtained above is adjusted by the timing adjustment device 2.
6 actuator 29 (step 61),
As a result, the intake and exhaust valves 16 and 17 are controlled to open and close at timings that correspond to the engine speed and load.

If roughness occurs while the opening/closing timing of the intake and exhaust valves 16 and 17 is being controlled in this manner, the CPU 45 increases the correction coefficient K by 1 (step 62), and adds this correction coefficient K to a predetermined value ΔTi. After correcting the opening/closing timing Ti (Ti+K・∆Ti) (step 63) and determining whether the overlap has become zero (a negative value at low rotation and high load, a positive value at other times) (step 63),
64), this corrected opening/closing timing Ti is given to the actuator 29 of the timing adjustment device 26 (step 65), and it is determined whether roughness has occurred in this state (step 66). It is determined whether or not the roughness level RK is smaller than the previous roughness level RK - 1 (step 67), and if it is smaller, the correction coefficient K is increased by 1 (step 68) and the process returns to step 63 above to perform the same process. On the other hand, this roughness level
If RK is greater than the previous roughness level RK-1, the correction coefficient K is decreased by 1 (step
69) Return to step 63 and perform the same process. In this way, when roughness occurs, the intake and exhaust valves 1
The opening/closing timings 6 and 17 are corrected in a direction according to the operating condition, and are controlled to the opening/closing timings at which the roughness level is minimized.

Further, when the overlap between the intake and exhaust valves 16 and 17 becomes zero while the roughness control is being performed in this manner, the roughness control is stopped. This is to prevent overcontrol.

Furthermore, if the engine is accelerated or decelerated while performing roughness control, the CPU 45 clears the correction coefficient K (step 70) and cancels the roughness control. This is because the roughness control may become overcontrolled due to torque fluctuations during acceleration and deceleration.

Here, intake and exhaust 16 when roughness occurs,
The method of correcting the opening/closing timing of No. 17 will be explained.

(i) At low rotation speeds and low loads, the closing timing EC of the exhaust valve 17 is early, and the opening timing EC of the intake valve 16 is early.
The opening/closing timing is corrected so that the opening/closing timing is delayed (see arrows A and B in FIG. 4). This reduces blowback of exhaust gas, reduces residual gas in the combustion chamber, improves combustion stability, and thereby suppresses roughness.

(ii) At low rotation speeds and high loads, the opening/closing timing is corrected so that the opening timing EO of the exhaust valve 17 is late and the closing timing IC of the intake valve 16 is early (see arrows C and D in Figure 4). ). This improves the effective expansion ratio and reduces blowback of intake air, thereby increasing the effective amount of work and reducing the influence of roughness caused by unstable combustion on the engine.

(iii) At high speeds, the opening timing of the exhaust valve 17
The opening/closing timing is corrected so that EO is early and the closing timing IC of the intake valve 16 is late (see arrows A and B in FIG. 4). As a result, more exhaust gas is discharged and residual gas is reduced, which improves combustion stability and suppresses roughness.Also, the inertia effect using the pressure difference between the cylinder and the intake port allows a large amount of intake air to be filled. This increases engine output and reduces the effects of roughness caused by unstable combustion.

Therefore, if we look at the overlap correction direction of the intake and exhaust valves 16 and 17 in each operating region when roughness occurs, as shown in Fig. 5, the correction is made in the direction that reduces the overlap at low rotation and low load, and at high rotation. Therefore, at low rotation speeds and high loads, the overlap is corrected to become larger.

The CPU 45 also applies a control signal to the control valve 11 of the bypass passage 10 to control the idle rotation speed, and also applies a fuel injection pulse to the fuel injection valve 6 according to the engine operating state and exhaust sensor output to control the fuel injection amount. It also controls the EGR amount by applying a control signal to the solenoid 15 of the EGR valve 14 according to the operating state of the engine, but its operation is the same as the conventional Kochi one, so a detailed explanation will be given below. Omitted.

In the device of this embodiment as described above, when roughness occurs, the opening/closing timing of the intake and exhaust valves is corrected so that the overlap between the intake and exhaust valves becomes smaller or larger depending on the operating state, so that the combustion state can be stabilized. The occurrence of roughness can be suppressed, the engine output can be increased to reduce the influence of roughness on the engine, and opening/closing timing can be controlled with higher precision.

Incidentally, in the above embodiment, a case has been described in which the opening and closing timing of the intake and exhaust valves is controlled, but the present invention uses, for example, a three-dimensional cam or adjusts the fulcrum position of the rocker arm to control the opening angle of the intake and exhaust valves. The same applies to controlling the
In this case, when roughness occurs, as shown in FIG. 7, for example, the overlap may be corrected in a direction that reduces the overlap at low rotations, and in a direction that increases the overlap at high rotations. At low engine speeds, the effective expansion ratio is improved by delaying the exhaust valve opening timing EO, and the blowback of the exhaust valve is reduced by advancing the exhaust valve opening timing EC. (See EX2 in Figure 6). Also, by delaying the opening timing IO of the intake valve, the blowback of exhaust gas is reduced, and by advancing the closing timing IC of the intake valve, the intake This is because blowback is reduced (see IN1 in Fig. 6), thereby improving combustion stability and reducing the influence of roughness on the engine. Also, at high speeds, the exhaust valve opening timing EO is set earlier.
By delaying the closing timing IC of the intake valve (see EX1 and IN1 in Figure 6), more exhaust gas can be discharged and more air can be taken in. This improves combustion stability and reduces roughness. This is because the impact can be reduced.

Note that the present invention is not limited to the above-mentioned embodiments, and can be modified in various ways. For example, correction of the opening/closing timing of the intake and exhaust ports at the time of occurrence of rough passage may be performed based on the request of the engine or by controlling the opening/closing timing. Depending on the method and the like, the opening/closing timing may be corrected in a direction different from that of the above embodiment, and the present invention suffices if the opening/closing timing is corrected in a direction that reduces the overlap at least at low rotations and low loads.

Further, in the above embodiment, a case has been described in which the opening/closing timing of both the intake port and the exhaust port is controlled, but the present invention can be similarly applied to a case where the opening/closing timing of either one is controlled.

〔Effect of the invention〕

As described above, according to the present invention, in an engine control device that variably controls the opening/closing timing of intake and exhaust ports depending on the engine operating condition, when engine roughness occurs at low rotation and low load, the intake and exhaust ports are closed. The opening/closing timing was corrected to reduce the overlap, so
This has the effect of making it possible to precisely control the timing of opening and closing the intake and exhaust ports.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram showing the configuration of the present invention.
FIG. 2 is a schematic configuration diagram of an engine control device according to an embodiment of the present invention, and FIG.
A diagram showing a flowchart of arithmetic processing of the CPU 45,
Both Figures 4 and 5 are diagrams for explaining the operation of the above device. Figure 4 is a diagram showing the opening and closing timing of the intake and exhaust valves, and Figure 5 is a diagram showing the opening and closing timing of the intake and exhaust valves when roughness occurs. Timing (overlap)
6 and 7 are diagrams for explaining other embodiments of the present invention.
This figure shows the opening angles of the intake and exhaust valves, and FIG. 7 is a diagram showing the direction of correction of the opening angles (overlap) of the intake and exhaust valves when roughness occurs. 50... Timing changing means, 51... Timing control means, 52... Roughness sensor, 53...
...Correction means, 71...Rotation speed detection means, 72...
Load detection means, 2a...Intake port, 7a...Exhaust port, 42...Vibration sensor, 45...CPU.

Claims (1)

[Scope of Claims] 1. Timing change means for varying the opening/closing timing of at least one of an intake port and an exhaust port of the engine; a timing control means for controlling the timing change means according to the operating state of the engine; vibration detection means that outputs a detection signal when vibration is detected; rotation speed detection means that detects engine rotation speed and outputs a detection signal when low rotation is detected; and rotation speed detection means that detects engine load and detects when low load is detected. load detection means for outputting a signal; and timing control means for controlling the timing control means to reduce the amount of overlap between the intake and exhaust ports when receiving all detection signals from the vibration detection means, the rotation speed detection means, and the load detection means. A control device for an engine, comprising: a correction means for correcting control of the engine.