JPH0562204B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake system for an engine equipped with an intake air recirculation mechanism for reducing pumping loss.

(Prior art) When the throttle valve is narrowed, intake resistance increases, pumping loss occurs, and fuel efficiency deteriorates. This problem occurs particularly in the low engine load range, and various proposals have been made to deal with this problem. One such method is to perform intake air recirculation. For example, in Japanese Patent Application Laid-Open No. 122315/1986, a recirculation passage is provided to recirculate a part of the intake air once introduced into the combustion chamber, and the intake air is returned to this passage. An intake device for an engine is disclosed in which the amount of intake air to be filled is controlled by controlling the flow rate.

(Problems to be solved) However, the intake air recirculation mechanism works to reduce the amount of intake air by discharging a portion of the intake air introduced into the combustion chamber to the outside of the combustion chamber. The problem is how to perform the acceleration control that is necessary to ensure high output.

(Means for solving the above problems) An object of the present invention is to provide an intake device with good acceleration response in an engine equipped with an intake air recirculation mechanism for reducing pumping loss. includes an intake passage that introduces intake air into the combustion chamber from an intake port that opens into the combustion chamber, a reflux passage that refluxes a part of the intake air introduced into the combustion chamber from a reflux port that opens into the combustion chamber, and the reflux passage. A recirculation control valve is provided to control the intake recirculation amount.

According to the present invention, when the operating state becomes accelerated, the recirculation control valve is once fully closed, and then the recirculation control valve is controlled to a recirculation amount corresponding to the accelerator opening degree. . In other words, when an acceleration state occurs, the reflux control valve is first fully closed to reduce the reflux amount to zero, and then the reflux control valve is opened depending on the degree of acceleration, that is, the accelerator opening. degree is adjusted. Further, in the device of the present invention, a throttle valve for controlling the amount of intake air can be provided in the intake passage in order to obtain a constant negative pressure state during deceleration. In this case, when the engine is operating at low load, the throttle valve is set to a predetermined initial opening and the recirculation control valve controls the intake air filling amount, and at high load operation, the recirculation control valve is fully closed and the throttle valve is closed. When acceleration of the engine is detected, the throttle valve is maintained at the initial opening when the acceleration is relatively weak and the load is low. At the same time, the opening degree of the reflux control valve is controlled to become smaller in accordance with the degree of acceleration. Further, when a high load state occurs due to strong acceleration, the recirculation control valve is fully closed and the opening degree of the throttle valve is controlled to increase in accordance with the degree of acceleration.

Preferably, even during deceleration, the recirculation control valve is once fully closed, and then adjusted to an opening degree corresponding to the degree of deceleration.

(Description of Embodiment) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

Referring to FIG. 1, the engine E in this example has four
It is a cylinder row type engine, and an intake port 5 is opened in the combustion chamber 2 of each cylinder 1, which communicates with a branched intake passage 4 branched from a surge tank 3. An air cleaner 7 is provided at the upstream end of the intake passage 6 extending upstream from the surge tank 3, and an air flow meter 8 is provided downstream of the air cleaner 7. Furthermore, a throttle valve 9 is provided downstream of the air flow meter 8, and an injector 10 for injecting fuel is installed near the combustion chamber 2 of each branch intake passage 4. A bypass passage 11 that bypasses the throttle valve 9 is connected to the intake passage 6, and a bypass valve 12 that controls the amount of bypass intake air flowing through the passage 11 is provided in the bypass passage 11. Further, a recirculation passage 13 is connected to the combustion chamber 2 and recirculates a part of the intake air introduced into the combustion chamber 2 through the intake passage 4. The recirculation passage 13 opens into the combustion chamber 2 at a recirculation port 14. There is. A reflux control valve 15 for controlling the amount of reflux from each cylinder 1 is installed in the reflux passage 13 . These reflux passages 13 are connected to communicate with each other, so that the intake air refluxed from each cylinder 1 is transferred to any other cylinder 1 during the intake stroke.
Sent again. Further, an exhaust port 17 of an exhaust passage 16 opens into the combustion chamber 2 . The three ports opening into the combustion chamber 2, that is, the intake port 5, the reflux port 14, and the exhaust port 17, are provided with an intake valve 18, a reflux valve 19, and an exhaust valve 20, respectively.
are combined to open and close these ports at predetermined timing. In this case, the recirculation valve 19 has an opening/closing timing that is slightly delayed from the intake valve 20, as shown in FIG. Throttle valve 9 is driven by throttle servo motor 2
1a, and the opening degree is controlled by the motor. The throttle valve 9 is connected to the accelerator pedal 21 via the throttle servo motor 21a, and when the amount of depression of the accelerator pedal exceeds a predetermined value, it begins to open and the amount of depression increases. The opening degree increases accordingly. Further, the reflux control valve 15 is connected to a control motor 22 which is also constituted by a servo motor.
The opening degree is adjusted according to the operation of 2, and thereby,
The amount of reflux can be controlled. In this example, as described above, the intake air amount is controlled by the throttle valve 9 and the bypass valve 12.
The reflux amount is controlled by a reflux control valve 15. In order to control the operation of the bypass valve 12 and the reflux control valve 15, in this example,
A controller 23 preferably comprised of a microcomputer is provided. controller 2
3, an air flow meter 8 for measuring the amount of intake air;
A throttle opening sensor 24 detects the opening of the throttle valve 9, a reflux valve opening sensor 15a detects the opening of the reflux control valve, and a reflux valve opening sensor 15a is attached to the surge tank 3 to detect the intake pressure downstream of the throttle valve 9 in the intake passage 6. a water temperature sensor 26 attached to the engine E to detect the engine cooling water temperature, and an O ₂ sensor 2 to detect the oxygen concentration in exhaust gas.
7 Furthermore, a signal from a rotation speed sensor 28 that detects the engine rotation speed is input. controller 2
3 calculates these input signals and outputs control signals to the throttle servo motor 21a and the recirculation control valve 15 to control the intake air amount and recirculation amount, and also outputs a command signal to the injector 10. to control the fuel injection amount.

Below, regarding the control of the intake air amount and recirculation amount in this example,
This will be explained with reference to FIGS. 3 and 4.

FIG. 3 is a flowchart for performing normal intake air amount and recirculation amount control in this example. The controller 23 initializes the memory before starting control. Next, necessary data such as engine cooling water temperature, accelerator opening, and engine speed are read, and based on these data, a target intake air amount Q _a corresponding to the accelerator opening is calculated. Then, it is determined from the engine load state whether the current operating state is in the range where the recirculation amount is controlled by the recirculation control valve 15 or the range where the intake air amount is controlled by the throttle valve 9. , issues a control command to the reflux control valve control motor 22 or the throttle servo motor 21a. In this case, if the current operating state is reflux control valve 1
5, as shown in FIG. 4, the recirculation valve opening calculation module calculates the recirculation control opening θ _R corresponding to the target intake air amount Q _a . After setting the opening θ _T of the throttle valve 9 to the initial opening, the recirculation control valve opening sensor 2
The control motor 22 is operated to reach the target opening θ _R according to the difference between the opening θ RR and the actual opening θ _RR of the recirculation control valve 15 from the openings 7 and 15 a. In this example, the initial opening degree of the throttle valve 9 is set to θ _IN , and by keeping the bypass valve 12 open, the initial opening degree of the throttle valve 9 can be substantially obtained at θ _IN . It's summery. Further, when the operating state of the engine is within a range in which intake air amount control should be performed by controlling the opening degree of the throttle valve 9, the controller 23 uses the throttle valve opening calculation module to calculate the target throttle amount corresponding to the target intake air amount _Qa. Calculate the opening degree θ _T. In this case, the opening θ _R of the recirculation control valve 15 is set to 0, and according to the difference between the actual throttle opening θ _TR from the throttle valve opening sensor 24 and the target throttle opening θ _T , The throttle opening is the target throttle opening θ _T
The throttle servo motor 21a is operated so that. Furthermore, although not shown in the flowchart, the controller 23 controls the intake air amount Q _a
The combustion injection amount Q _f corresponding to is calculated, and an injection command signal is output to the injector 10 after being corrected by various modules shown in FIG.

By performing the above control, as shown in FIG. 5, in a region where the engine load is low, the throttle valve 9 is maintained at the initial opening θ _IN , and the opening of the recirculation control valve 15 is maintained at the opening θ IN. It decreases in proportion to the increase in load. Therefore, as the load increases, the amount of recirculation decreases and the amount of intake air charged into the combustion chamber increases. Then, when the engine load reaches a predetermined value, the recirculation control valve 15 is fully closed, and when the load increases thereafter, the opening degree of the throttle valve 9 increases accordingly. As a result, the intake air amount increases and the intake air filling amount increases. FIG. 6 is a flowchart of acceleration control in this example. That is, when an acceleration state is detected due to a change in accelerator opening, etc., the recirculation control valve is temporarily fully closed. Then, the throttle opening θ _T corresponding to the required intake air amount at that time is calculated, and the opening of the throttle valve 9 is adjusted according to the above procedure so as to reach the calculated value. Then, when the acceleration state is released, the normal intake air amount and recirculation amount are controlled according to the procedure shown in FIG. This control will be explained with reference to FIGS. 7 and 8.
The figure shows that in Fig. 5, the accelerator opening degree changes from θ ₃ to θ _1.
This relates to the case where _a relatively weak acceleration operation is performed, such as a change to At _T2 , the controller 23 detects the start of acceleration. Upon detecting acceleration, the controller 23 activates the reflux control valve 1.
A fully close command is output to the 5 motor 22. As a result, the reflux control valve 15 operates in the closing direction,
After a certain operating time, it becomes fully closed at time _T3 .
Then, when the accelerator opening stops increasing at time T ₄ , the controller 23 detects the completion of acceleration at time T ₅ with a certain time delay, and the recirculation control valve 15
A command signal is output to the control motor 22 so that the opening degree corresponds to the accelerator opening degree at that time. In this case, since the load condition at the time of completion of acceleration is relatively low, the throttle valve is maintained at the initial opening degree. In Fig. 5, in a relatively strong acceleration state where the accelerator opening changes from θ ₃ to θ ₂ ,
As shown in FIG. 8, when the recirculation control valve is fully closed and acceleration is completed, the throttle valve 9 is opened to a predetermined opening according to the intake request, and the required intake air filling amount is secured. If throttle opening control is required during acceleration, the recirculation control valve is once fully closed, and then the throttle valve 9 is opened in response to a request.

In this example, in order to set the actual initial opening degree θ _IN of the throttle valve 9, the bypass passage 1 is
1 and a bypass valve 12, it is not necessary to do so, and the initial opening may be ensured by setting the opening of the throttle valve to a predetermined opening.

FIG. 9 shows another example in which the acceleration control of this example is applied to an engine without a throttle valve. In this case, the reflux control valve is once fully closed, and then the acceleration is completed. The opening degree is adjusted according to the load condition at the time.

(Effects of the Invention) According to the present invention, in an engine equipped with an intake air recirculation device, when the engine accelerates, the recirculation control valve is temporarily fully closed.
It is possible to ensure a high filling amount of intake air with good responsiveness, and therefore, it is possible to obtain acceleration performance with good responsiveness.

[Brief explanation of the drawing]

FIG. 1 is an overall schematic diagram of an engine according to an embodiment of the present invention, FIG. 2 is a characteristic diagram showing valve timing, and FIG. 3 is a flowchart No. 4 showing an example of control according to the present invention. The figure is a diagram of the operation system of the controller, Figure 5 is a graph showing changes in the opening degrees of the reflux control valve and the throttle valve, Figure 6 is a flowchart of acceleration control in this example, and Figures 7 and 8 are FIG. 9 is a time chart showing changes in the opening degree of the reflux control valve and the throttle valve in another embodiment. E... Engine, 1... Cylinder, 4, 6...
Intake passage, 9...Throttle valve, 10...Injector, 12...Bypass valve, 15...Recirculation control valve, 21a...Throttle servo motor, 22...
...control motor.

Claims (1)

[Claims] 1. An intake passage that introduces intake air into the combustion chamber from an intake port that opens into the combustion chamber, a reflux passage that refluxes a part of the intake air introduced into the combustion chamber from a reflux port that opens into the combustion chamber, and A recirculation control valve is provided to control the intake recirculation amount, and when the operating state becomes an acceleration state, the recirculation control valve is temporarily fully closed, and then the recirculation control valve controls the recirculation amount corresponding to the accelerator recirculation amount. An intake system for an engine, characterized in that it is configured to.