JPH0763123A - Exhaust gas recirculation control device for internal combustion engine - Google Patents

Abstract

(57) [Abstract] [Purpose] An exhaust gas recirculation control device for an internal combustion engine that can ensure the responsiveness and control accuracy of a negative pressure responsive exhaust gas recirculation control valve even if the magnitude of the negative pressure of a negative pressure source fluctuates. To provide. [Structure] An exhaust passage 3 and an intake passage 2 of a gasoline engine 1 are connected by an exhaust gas recirculation passage 5. A negative pressure responsive exhaust gas recirculation control valve 6 is arranged in the middle of the exhaust gas recirculation passage 5. The negative pressure control device 33 includes a negative pressure solenoid valve 12 that controls communication between the negative pressure chamber 10 and intake negative pressure of the engine 1, and an atmospheric solenoid valve that controls communication between the negative pressure chamber 10 and the atmosphere. 15 and. The CPU applies a negative pressure control device 33 for applying an operating negative pressure corresponding to the target exhaust gas recirculation amount to the negative pressure chamber 10 of the negative pressure responsive exhaust gas recirculation control valve 6.
The target duty ratio of the negative pressure solenoid valve 12 is corrected according to the magnitude of the negative pressure of the intake negative pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas recirculation control device for an internal combustion engine having a negative pressure responsive exhaust gas recirculation control valve.

[0002]

2. Description of the Related Art Conventionally, exhaust gas purification of an internal combustion engine, especially N
A so-called EGR device that recirculates a part of exhaust gas to intake air is provided for the purpose of purifying the O _x component. A typical conventional EGR device has a negative pressure responsive exhaust gas recirculation control valve (negative pressure responsive EGR valve) and controls the communication between the negative pressure chamber of the exhaust gas recirculation control valve and the negative pressure source. A device that includes a solenoid valve and a second solenoid valve that controls communication between the negative pressure chamber and the atmosphere is common.

The target exhaust gas recirculation amount is determined by the load of the internal combustion engine, the number of revolutions, the pressure difference between the exhaust passage and the intake passage, and the operating negative pressure corresponding to the target exhaust gas recirculation amount of the first and second solenoid valves. It is controlled by the valve opening time, and further, it is disclosed in JP-A-63-22794.
As described in Japanese Unexamined Patent Publication (Kokai) No. 7, the opening times of the first and second solenoid valves are controlled with different duty ratios, and EG
A technique is known in which the R valve is opened and closed in such a manner that the responsiveness and the resolution are both optimized.

[0004]

However, the opening time of the first solenoid valve for controlling the communication of the negative pressure source, the EGR valve moving speed, and the EGR valve moving amount change depending on the magnitude of the negative pressure. Even if the source is set to a variable place like a surge tank of an internal combustion engine, or even if a vacuum pump is used, a constant negative pressure cannot be created. The responsiveness and control accuracy changed, and the predetermined duty ratio could not always be the optimum value.

Therefore, an object of the present invention is to provide exhaust gas recirculation for an internal combustion engine which can ensure the responsiveness and control accuracy of a negative pressure responsive exhaust gas recirculation control valve even if the negative pressure of the negative pressure source fluctuates. It is to provide a control device.

[0006]

SUMMARY OF THE INVENTION According to the present invention, an exhaust gas recirculation passage communicating an exhaust passage and an intake passage of an internal combustion engine, and an exhaust gas recirculation passage disposed in the middle of the exhaust gas recirculation passage for controlling an exhaust gas recirculation amount. A pressure responsive exhaust gas recirculation control valve and a communication between the negative pressure chamber and a negative pressure source for applying an operating negative pressure corresponding to a target exhaust gas recirculation amount to the negative pressure chamber of the exhaust gas recirculation control valve. In the exhaust gas recirculation control device for an internal combustion engine, the exhaust gas recirculation control device is provided with a negative pressure control means having a first electromagnetic valve for controlling the communication between the negative pressure chamber and the atmosphere. With respect to the target duty ratio of the first solenoid valve of the negative pressure control means for applying the operating negative pressure corresponding to the target exhaust gas recirculation amount to the negative pressure chamber of the control valve, the magnitude of the negative pressure of the negative pressure source is set. According to the exhaust gas recirculation control device for the internal combustion engine, the target duty ratio is corrected accordingly. It is an aspect.

Here, the negative pressure source may be intake negative pressure of the internal combustion engine.

[0008]

With respect to the target duty ratio of the first solenoid valve of the negative pressure control means for applying the operating negative pressure corresponding to the target exhaust gas recirculation amount to the negative pressure chamber of the negative pressure responsive exhaust gas recirculation control valve, the negative pressure is reduced. The target duty ratio is corrected according to the magnitude of the negative pressure of the source. Therefore, even if the negative pressure of the negative pressure source fluctuates, the target duty ratio of the first solenoid valve is corrected, and the responsiveness and control accuracy of the exhaust gas recirculation control valve are ensured.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an overall configuration diagram of an exhaust gas recirculation control device for an internal combustion engine.

An intake passage (intake pipe) 2 and an exhaust passage (exhaust pipe) 3 are connected to a gasoline engine (internal combustion engine) 1. The exhaust passage 3 and the intake passage 2 communicate with each other through the exhaust gas recirculation passage 5. That is, one end of the exhaust gas recirculation passage 5 is opened downstream of the throttle valve 4 in the intake passage 2, and the other end of the exhaust gas recirculation passage 5 is connected to the exhaust passage 3
It is open to. Then, a part of the exhaust gas is recirculated to the intake passage 2 from the exhaust passage 3 through the exhaust gas recirculation passage 5. A negative pressure responsive exhaust gas recirculation control valve 6 is provided in the exhaust gas recirculation passage 5. The exhaust gas recirculation amount is adjusted by the negative pressure responsive exhaust gas recirculation control valve 6.

The negative pressure responsive exhaust gas recirculation control valve 6 has a valve body 7, which is supported by a diaphragm 8 via a rod 9. The exhaust gas recirculation passage 5 is opened and closed by the movement of the valve body 7. The negative pressure responsive exhaust gas recirculation control valve 6 has a negative pressure chamber (diaphragm chamber) 10 partitioned by a diaphragm 8 and an atmosphere chamber 11.

The negative pressure responsive exhaust gas recirculation control valve 6 is provided with a negative pressure control device (negative pressure control means) 33 as described below. The negative pressure chamber 10 is connected to a negative pressure outlet 14 directly downstream of the throttle valve 4 of the intake passage 2 through a negative pressure introduction passage 13 having a negative pressure solenoid valve (first electromagnetic valve) 12. Further, the negative pressure chamber 10 is communicated with the atmosphere through an atmosphere introducing passage 16 having an atmosphere solenoid valve (second electromagnetic valve) 15. On the other hand, a compression coil spring 17 is arranged in the negative pressure chamber 10. Then, the diaphragm 8 is displaced against the spring force of the coil spring 17 by the combined negative pressure formed by the intake negative pressure (intake pipe negative pressure) of the gasoline engine 1 and the atmospheric pressure to control the opening degree of the valve body 7. However, the effective passage area of the exhaust gas recirculation passage 5 is increased as the negative pressure of the negative pressure chamber 10 is increased.

In this way, by controlling the negative pressure solenoid valve 12 and the atmospheric solenoid valve 15, the negative pressure chamber 10
Of the negative pressure responsive exhaust gas recirculation control valve 6 corresponding to the target exhaust gas recirculation amount by controlling the communication between the negative pressure chamber 10 and the atmosphere, or the communication between the negative pressure chamber 10 and the atmosphere. Negative pressure can be applied.

Further, the negative pressure responsive exhaust gas recirculation control valve 6 is provided with a lift amount detecting sensor 18, which detects the moving amount of the valve body 7, that is, the lift amount of the valve body 7. It

On the other hand, the control device 19 includes an intake negative pressure sensor 2
0 is connected, and the control device 19 inputs the detection signal S1 of the intake negative pressure of the gasoline engine 1 from the intake negative pressure sensor 20. An engine speed sensor 21 is connected to the control device 19, and the control device 19 inputs an engine speed detection signal S2 from the engine speed sensor 21. further,
The lift amount detection sensor 18 is connected to the control device 19,
The control device 19 inputs the lift amount detection signal Ps of the valve body 7 from the lift amount detection sensor 18. Further, a storage device 22 is connected to the control device 19, and the control device 19 is connected to the storage device 2
Input the memory signal from 2. The control device 19 outputs a control signal to the negative pressure solenoid valve 12 to control the opening and closing (duty control) of the negative pressure solenoid valve 12. Similarly, the control device 19 outputs a control signal to the atmospheric solenoid valve 15 to control the opening / closing of the atmospheric solenoid valve 15 (duty control).
It is supposed to do.

FIG. 2 shows a specific configuration of the control device 19. The control device 19 is a central processing unit (hereinafter, CP).
U) 23, memories 24 and 25, an input interface circuit 26, an interface circuit 27, an analog multiplexer 28, an AD converter 29, and a counter 30. The input interface circuit 26 is for inputting the detection signal of the engine speed sensor 21, and the interface circuit 27 is for the negative pressure solenoid valve 12.
And for outputting a control signal to the atmospheric solenoid valve 15. The analog multiplexer 28 is for inputting the outputs of the intake negative pressure sensor 20 and the lift amount detection sensor 18, and the AD converter 29 AD-converts the output of the analog multiplexer 28. The counter 30 counts the signal pulses from the engine speed sensor 21 and detects the engine speed. Each of the above devices 23, 24, 2
5, 26, 27, 29 and 30 are connected to each other by an address / data bus 31, and address signals and data are exchanged. Further, each of the above devices 23, 24, 25,
Control bus 3 between 26, 27, 28, 29 and 30
The two are connected to each other, and control signals are exchanged.

A map (map 1) shown in FIG. 3 is stored in the storage device 22. The map 1 corresponds to the optimum exhaust gas recirculation amount obtained by the current engine speed Ne detected by the engine speed sensor 21 and the current intake negative pressure Pm detected by the intake negative pressure sensor 20. Target value Pr of lift amount of the negative pressure responsive exhaust gas recirculation control valve 6
Has been incorporated. That is, the target value Pr of the lift amount for applying the operating negative pressure corresponding to the target exhaust gas recirculation amount to the negative pressure chamber 10 is stored. It should be noted that in the map 1, target values Pr of lift amount are prepared in a matrix form for each predetermined engine speed and each predetermined intake negative pressure.

Further, the memory 25 stores a map (map 2) shown in FIG. In this map 2,
The deviation value P (= Pr−Ps) between the target value Pr of the lift amount of the negative pressure responsive exhaust gas recirculation control valve 6 and the current detected value Ps, and the duty ratio of the negative pressure solenoid valve 12 and the atmospheric solenoid valve 15 The relationship is remembered. This duty ratio is set to increase as the absolute value of the deviation value P increases. Further, this map 2 shows a dead zone for holding the negative pressure responsive exhaust gas recirculation control valve 6 in that state when the lift amount detection value Ps of the negative pressure responsive exhaust gas recirculation control valve 6 is close to the target value Pr. Have an area. This is for stabilizing the control and improving the durability of the solenoid valves 12 and 15 by deactivating the solenoid valves 12 and 15.

Further, the memory 25 stores a map (map 3) shown in FIG. The map 3 stores the correction coefficient α for the duty ratio of the negative pressure solenoid valve 12 obtained in the map 2 according to the intake negative pressure Pm detected by the intake negative pressure sensor 20. The correction coefficient α is set to be smaller as the intake negative pressure Pm is smaller.

That is, even if the duty ratio of the negative pressure solenoid valve 12 is the same, the response speed and movement amount of the negative pressure responsive exhaust gas recirculation control valve 6 change depending on the magnitude of the negative pressure. The negative-pressure responsive exhaust gas recirculation control valve is corrected by correcting the duty ratio of the negative-pressure solenoid valve 12 obtained from the map 2 according to the intake negative pressure Pm detected by the pressure sensor 20 to obtain any negative pressure. The responsiveness of 6 in the valve opening direction is ensured, and sufficient resolution is ensured for the small amount control of the negative pressure responsive exhaust gas recirculation control valve 6.

Next, the operation of the exhaust gas recirculation control device will be described with reference to FIGS.
It will be described based on the flowchart shown in FIG. The processes shown in FIGS. 6 and 7 are started every predetermined time. First, in step 100, the CPU 23 reads the engine speed Ne from the output of the engine speed sensor 21, and stores the value in the storage area M1 of the memory 24 in FIG. Similarly, the CPU 23 reads the intake negative pressure Pm from the output of the intake negative pressure sensor 20 in step 101 and stores the value in the storage area M2 of the memory 24. Then the CPU
In step 102, 23, the target lift amount Pr of the negative pressure responsive exhaust gas recirculation control valve 6 is obtained from the map 1 of FIG. Store in area M3. And CPU2
In step 103, the current lift amount Ps of the negative pressure responsive exhaust gas recirculation control valve 6 is obtained from the output of the lift amount detection sensor 18 in step 103, and in step 104 the target value Pr and the current detection value Ps are obtained.
The deviation value P (= Pr−Ps) between

Further, the CPU 23 executes the step 10 in FIG.
5, the deviation value P of the lift amount is within a predetermined range (-a≤P≤a)
If it is within the predetermined range, the negative pressure solenoid valve 12 and the atmospheric solenoid valve 15 are both closed at step 106 to stabilize the control and the solenoid valves 12, 15 To ensure the durability of.

On the other hand, when the CPU 23 determines in step 105 that the lift amount of the negative pressure responsive exhaust gas recirculation control valve 6 is not within the dead zone (-a≤P≤a), step 10
In step 7, it is determined whether the deviation value P is smaller than the lower limit value -a of the dead zone. That is, it is determined whether the lift amount of the negative pressure responsive exhaust gas recirculation control valve 6 should be reduced or increased, in other words, whether the atmosphere should be introduced into the negative pressure chamber (diaphragm chamber) 10 or the negative pressure should be introduced. . Here, CPU2
3 becomes P <-a, and when it is determined that the atmosphere should be introduced into the negative pressure chamber (diaphragm chamber) 10, the deviation value P obtained in step 104 is used to calculate the map 2 in FIG.
The target duty ratio D1 of the atmospheric solenoid valve 15 is read in, the atmospheric solenoid valve 15 is driven at the target duty ratio D1 in step 109, and the negative pressure solenoid valve 12 is closed to complete the process.

On the other hand, when the CPU 23 determines in step 107 that P ≧ -a and the negative pressure should be introduced into the negative pressure chamber (diaphragm chamber) 10, first, in step 110, the deviation value P obtained in step 104 is set. The target duty ratio D2 of the negative pressure solenoid valve 12 is obtained from the map 2 of FIG. Further, the CPU 23 executes the step 1 in the step 111.
Based on the intake negative pressure Pm obtained in 01, the negative pressure correction coefficient α is obtained from the map 3 in FIG. Next, in step 112, the CPU 23 sets the target duty ratio D of the negative pressure solenoid valve 12.
The negative pressure solenoid valve 12 is duty-controlled with a value (= α · D2) obtained by multiplying 2 by the negative pressure correction coefficient α, and the atmospheric solenoid valve 15 is closed to end the processing.

As described above, in this embodiment, the negative pressure solenoid valve 12 (first valve) for applying the working negative pressure corresponding to the target exhaust gas recirculation amount to the negative pressure chamber 10 of the negative pressure responsive exhaust gas recirculation control valve 6 is used.
Target duty ratio D2 of the solenoid valve) of the gasoline engine 1 (internal combustion engine) according to the magnitude of the negative pressure of the intake negative pressure (negative pressure source) of the gasoline engine 1 (internal combustion engine).
2) (steps 110 to 11 in FIG. 7)
2). Therefore, even if the magnitude of the negative pressure introduced into the negative pressure chamber (diaphragm chamber) 10 of the negative pressure responsive exhaust gas recirculation control valve 6 changes, the optimum response speed and control accuracy according to the negative pressure are ensured. You can

The present invention is not limited to the above embodiment. For example, in the above embodiment, a system for measuring the intake negative pressure (intake pipe negative pressure) by the DJ system by a pressure sensor is used. As an example, the intake negative pressure may be predicted from the intake amount and the engine speed even in the LJ system.

Further, in the above embodiment, the negative pressure source is the intake negative pressure (intake pipe internal pressure) of the internal combustion engine, but it may be a vacuum pump or the like. That is, even in the vacuum pump, the negative pressure cannot be kept constant, so the target duty ratio of the negative pressure solenoid valve 12 may be corrected according to the magnitude of the negative pressure.

[0028]

As described above in detail, according to the present invention,
Even if the magnitude of the negative pressure of the negative pressure source fluctuates, the negative pressure responsive exhaust gas recirculation control valve exerts an excellent effect of ensuring the responsiveness and control accuracy.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an exhaust gas recirculation control device for an internal combustion engine.

FIG. 2 is an electrical configuration diagram of an exhaust gas recirculation control device for an internal combustion engine.

FIG. 3 is a map that stores a target lift amount.

FIG. 4 is a map storing a duty ratio of a solenoid valve.

FIG. 5 is a map storing correction coefficients.

FIG. 6 is a flowchart for explaining the operation of the exhaust gas recirculation control device for an internal combustion engine.

FIG. 7 is a flow chart for explaining the operation of an exhaust gas recirculation control device for an internal combustion engine.

[Explanation of symbols]

 1 Gasoline engine as an internal combustion engine 2 Intake passage 3 Exhaust passage 5 Exhaust gas recirculation passage 6 Negative pressure responsive exhaust gas recirculation control valve 10 Negative pressure chamber 12 Negative pressure solenoid valve as first solenoid valve 15 As second solenoid valve Solenoid valve of atmospheric solenoid valve for negative pressure 33 Negative pressure control device as negative pressure control means

Claims (2)

[Claims] 1. An exhaust gas recirculation passage communicating between an exhaust passage and an intake passage of an internal combustion engine, and a negative pressure responsive exhaust gas recirculation control valve disposed in the middle of the exhaust gas recirculation passage for controlling an exhaust gas recirculation amount. A first solenoid valve for controlling communication between the negative pressure chamber and the negative pressure source for applying an operating negative pressure corresponding to a target exhaust gas recirculation amount to the negative pressure chamber of the exhaust gas recirculation control valve, In an exhaust gas recirculation control device for an internal combustion engine, comprising: a negative pressure control means having a second electromagnetic valve for controlling communication between the negative pressure chamber and the atmosphere, a target for the negative pressure chamber of the exhaust gas recirculation control valve. The target duty ratio of the first solenoid valve of the negative pressure control means for applying the operating negative pressure corresponding to the exhaust gas recirculation amount is corrected in accordance with the negative pressure of the negative pressure source. An exhaust gas recirculation control device for an internal combustion engine, characterized in that 2. The exhaust gas recirculation control device for an internal combustion engine according to claim 1, wherein the negative pressure source is an intake negative pressure of the internal combustion engine.