JPS63198766A - Exhaust gas recirculation control device for diesel engine - Google Patents

Abstract

PURPOSE:To reliably prevent smoke from occurring by closing an opening/ closing valve provided on an exhaust gas circulation passage to stop the circulation of the exhaust gas when an accelerator pedal is depressed to start a quick acceleration state during the operation of EGR. CONSTITUTION:The first opening/closing valve E capable of adjusting the exhaust gas circulation quantity and the second opening/closing valve F opening or closing a circulation passage D in response to the electric signal are provided on the circulation passage D communicating an intake passage B and an exhaust passage C of a Diesel engine A. Various operation states containing at least the load state of the Diesel engine A are detected by an operation state detecting means G, and the opening of the first opening/closing valve E is controlled by the first control means H based on the detection result. If the second control means I judges that the load detected by the operation state detecting means G has been changed by a preset value or more, this control means I controls to fully close the second opening/closing valve F.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exhaust gas recirculation control device that recirculates part of the exhaust gas of a diesel engine to an intake passage. The present invention relates to an exhaust gas recirculation control device having a

[Prior art] Conventionally, this type of exhaust gas recirculation control device (hereinafter referred to as EGR)
nitrogen oxides (N.) in exhaust gas.

x) It is widely used in diesel engines as a means to reduce

In a diesel engine equipped with such EGR,
If the amount of fuel increases due to acceleration during EGR operation, there will be a lack of oxygen and smoke will likely occur. Especially from low load to high negative load? , Partial smoke is more likely to occur during accelerated driving.

As a means to solve this problem, a filter device is known that prevents the generation of smoke by delaying or reducing the increase in fuel amount. However, with this method, the feeling of acceleration will be impaired.There are 5 problems.

As a conventional technique for solving this problem, for example, there is a technique disclosed in Japanese Patent Application Laid-Open No. 1987-1987.

That is, in the technique disclosed in this publication, the amount of recirculation of exhaust gas is reduced by adjusting the opening degree of a diaphragm valve as the engine load increases, including during sudden acceleration.

In addition, as another conventional technique, Japanese Patent Application Laid-Open No. 60-21944
As described in Publication No. 4, a diaphragm type valve is provided in the exhaust passage, and this valve is opened during acceleration to limit the amount of recirculation of exhaust gas.

[Problems to be Solved by the Invention] However, in all of the above conventional technologies, the recirculation of exhaust gas is stopped or restricted by adjusting the opening of a diaphragm valve using a negative pressure circuit. Due to the delay in the control of the pressure circuit, the response is not good and it is not sufficient to prevent smoke from occurring.

[Means for Solving the Problems] The present invention has been made to solve the above problems, as shown in FIG. at least a diesel engine; An operating state detecting means G for detecting various operating states including the load state of A, and receiving a detection signal from the operating state detecting means G and controlling the opening degree of the first on-off valve E based on the detected signal. 1. When it is determined that the load detected by the operating state detecting means G has changed by a predetermined amount or more; The gist of the present invention is an exhaust gas circulation control device for a diesel engine, which is equipped with a second control means (2) that controls the second on-off valve F to be fully open.

Here, the above-mentioned first on-off valve E is, for example, a negative pressure; in addition to including a diaphragm type valve that adjusts the opening degree of the recirculation passage as required, the opening degree can also be adjusted according to the amount of current applied to the solenoid. A strong solenoid valve may also be used. Further, the second on-off valve F refers to a solenoid valve or the like that can be fully closed and fully opened instantaneously by an electric signal C4'.

The second on-off valve F is preferably provided in the open recirculation passage between the first on-off valve E and the intake passage B in order to increase the function of instantly stopping the reflux gas. It may be provided between E and the intake passage C.

The operating state detection means G refers to, for example, a sensor for detecting the amount of depression of an accelerator pedal that outputs a signal corresponding to the load of the engine, a rotation speed sensor that detects the rotation speed of the engine, or the like.

[Operation] In the present invention, the exhaust gas in the exhaust passage C is recirculated through a recirculation passage having a first on-off valve E and a second on-off valve F, thereby controlling the recirculation of the exhaust gas. Then, the recirculation amount of exhaust gas is determined by the first on-off valve E based on the detection signal from the operating state detection means G.
This is done by controlling the opening.

Further, when the second control fffl1 means (2) determines that the engine page surface from the operating state detection means G has changed by more than a predetermined value, an electric signal is output to the second on-off valve F.
Exhaust gas recirculation is immediately stopped.

[Example code] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a schematic diagram showing a diesel engine equipped with EGR and its peripheral equipment. In the figure B, 1 is a diesel engine main body, and a piston 5 is slidably fitted into the cylinder block 3.
A combustion chamber 7 surrounded by a piston 5 is provided. This combustion chamber 7 communicates with an intake passage 11 and an exhaust passage 13 mounted on the cylinder head 9. A recirculation passage 15 for recirculating exhaust gas is connected between the exhaust passage 13 and the intake passage 11.
The third side is connected by a boat 17, while the intake passage 11 side is connected by one boat.

In addition, an EGR control well 21 is located in the middle of the recirculation passage 15.
(first on-off valve) and cut valve 23 (second on-off valve)
is being thrown.

The El control valve 21 has a housing 25 divided into an atmospheric chamber 29 and a negative pressure chamber 31 by a diaphragm 27, and a rod 3 is provided on the surface of the diaphragm 27 on the atmospheric chamber 29 side.
A valve body 33 is attached via 1, and this valve body 33 opens and closes the valve seat 35 and opens and closes the recirculation passage 15. On the other hand, a compression spring 35 applies a spring force to the surface of the diaphragm 27 on the negative pressure chamber 31 side, and the pressure difference between the atmospheric chamber 29 and the negative pressure chamber 31 forces the diaphragm 27 against the spring force. moves to adjust the opening degree of the valve.

The negative pressure chamber 31 of the EGR control valve 21 is connected to a negative pressure regulating valve 37 via a conduit 36.
The negative pressure supplied from the negative pressure supply device 39 is adjusted.

The passage 40 in the EGR control valve 21 is connected to a pipe 41 of the recirculation passage 15, and the cut valve described above is turned on and off depending on whether or not the electromagnetic solenoid is energized. 23 (second on-off valve) is provided.

The diesel engine is also equipped with various sensors and switches, including a water temperature sensor 51 that detects the temperature of the cooling water, and an accelerator opening sensor 53 that outputs a signal according to the amount of depression of the accelerator pedal.
There is a rotation speed sensor 55 that detects the rotation speed of the diesel engine, and an idle switch 5 that operates in conjunction with the accelerator pedal and detects the idle state.
7 etc.

Detection signals from the various sensors and switches described above are input to an electronic control device 61, and actuators such as the negative pressure control valve 37 are driven and controlled by the electronic control fffj device 61. The electronic control device 61 is composed of a well-known microcomputer, and includes a human output interface 63 that processes human input signals from various sensors into digital signals that can be processed by a computer, converts them into drive signals for actuators, and arithmetic processing. It is composed of a CPU 65, RA and MB2 as temporary storage means, and a ROM 69 in which various control programs are stored in advance.

The operation of the exhaust gas recirculation control device is calculated according to the control program stored in the ROM 69. That is, the exhaust gas recirculation amount is calculated based on the water temperature TV/%, the accelerator opening Ac, and the rotation speed Ne. A signal according to the result is sent to the negative pressure control valve 37, and the EGR control valve 2
The pressure in negative pressure chamber 31 of No. 1 is controlled. As a result, the diaphragm 27 moves and the valve opening degree is adjusted, thereby changing the amount of recirculation of exhaust gas.

Furthermore, if it is determined that there is a change in the engine load exceeding a predetermined value based on the detection signal from the accelerator opening sensor 53, a close signal is output to the normally open cut valve 23, and the recirculation of exhaust gas is stopped. Ru.

Next, the control executed according to the program stored in the ROM 69 of the electronic control unit 61 will be explained in detail with reference to the flowcharts of FIGS. 3 and 4.

In FIG. 3, first, in step 100, data is read, that is, the water temperature Tw is read from the water temperature sensor 4/51, and the data is read from the rotation speed sensor 55.

The engine rotation r&Ne and the accelerator opening Ac are read from the accelerator opening sensor 53, respectively.

Subsequently, in step 110, EG is determined based on the water temperature Tw.
It is determined whether or not the permission condition of R is satisfied, and when the EGR control is in the permission state, the process proceeds to step 120, and the negative pressure corresponding to the predetermined exhaust gas recirculation amount is set based on the engine rotation speed Ne and the accelerator opening degree Ac. and calculates the valve opening degree of the EGR control valve 21. In the next step 130, by adjusting the opening degree of the negative pressure regulating valve 37, the EGRVJi
After executing wholesale and setting the EGR control flag FEGR indicating the execution state of EGH control to 1, the process returns to step 100.

On the other hand, if it is determined in step 110 that the EGR permission conditions are not met, then in step 140 the EGR
At the same time as stopping the control, the EGR control flag FIEG
After resetting R to O, the process returns to step 100.

This process controls the amount of EGR waste recirculation.

Next, the control executed as υ'' inclusion processing at predetermined time intervals for the I;IJ control described in the flowchart of FIG. 3 will be described in accordance with the flowchart of FIG. 4.

First, in step 150, data is read, that is, the accelerator opening degree Ac is read. In the following step 160, it is determined whether or not EGR is in operation.
This is done by determining the R training flag F EGR. here,
If it is determined that the EGR is not in operation, the process moves to step 170 and the force t=23 is set to fully open.

On the other hand, if it is determined that it is in the operating state, it is determined in step 180 whether or not it is in the high speed state. If the deviation from the opening is greater than a predetermined order, it is determined that sudden acceleration has been commanded (,
2. Fully close the cut 23 (step 190).

- On the other hand, if the deviation is less than a predetermined value and it is determined that there is no acceleration, the cut valve 23 is kept fully open.

Therefore, according to the above embodiment, when the accelerator pedal is depressed during EGR operation and a sudden acceleration command is issued, the recirculation of exhaust gas is immediately stopped by the cut valve 23, thereby preventing the generation of smoke. can be prevented.

Next, a modification of the process shown in FIG. 4 will be described using FIG. 5. First, in step 200, the EGR control flag F EGR is determined, and the flag F EGR is set to 1.
If not, the process proceeds to step 210 and the cut valve 23
Set to full open state. This is because during normal running, the cut valve 23 is set to the fully open state and the 5EGR recirculation amount is controlled only by the EGR control valve 21.

On the other hand, if the flag F EGR is 1, that is, E
If GR control is being executed, the process moves to step 220 and data is read. Here, the accelerator opening Ac and engine rotation speed Ne corresponding to the engine load are read as data.

Based on these detection signals, the EG (not shown in FIG. 6) is
A determination is made as to whether or not it is in the R region, and if it is determined that it is not in the EGR operation region, a fully closed signal is output to the cut valve 23 in step 240.

This immediately stops the exhaust gas reflux.

On the other hand, if it is determined at step 230 in FIG. 5 that the area is in the EGR region, the process proceeds to the next step 250.
The engine load r calculated in the previous process, that is, the accelerator opening A c (n-1), and the current accelerator opening Ac (n
), and in step 260, if the shoulder difference is greater than a predetermined value, the cut valve 23 immediately stops the recirculation of the JJF gas; on the other hand, if the deviation is greater than a predetermined value, In step 210, the cut valve 2IO is kept open in order to maintain the EGR operating state.

That is, step 210, steps 240 to 210
To explain the process using the map shown in Figure 6, which sets the EGR region determined by the accelerator opening (engine load) and engine speed, now tE
('= R”T) From the state located at al in the region,
Depress the accelerator pedal and activate EGR.
When a command to shift to step 2 is issued, the recirculation of exhaust gas is stopped by closing the valve I/valve 23. Further, when a command is output to shift the accelerator opening degree Ac from the state of l)+ to b2, and when the deviation is large, the recirculation of exhaust gas is stopped by the cut valve 23 even if it is within the EGR operation region,
On the other hand, when the deviation from bl to b9 is small, the cut valve 23 remains open and continues to recirculate the exhaust gas.

Therefore, according to the embodiment shown in FIG. 5, even when a sudden acceleration command is output even within the EGR region, the cut valve 2
3, the recirculation of exhaust gas is immediately stopped, making it possible to more effectively prevent the occurrence of smoke during acceleration.

[Effects of the Invention] As explained above, according to the present invention, when the accelerator pedal is depressed during EGR operation and an acceleration command is issued, the recirculation of exhaust gas is immediately stopped. The generation of smoke can be effectively prevented.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of the basic structure of the present invention, Fig. 2 is a block diagram showing a diesel engine and its peripheral equipment according to an embodiment of the present invention, and Figs. 3 and 4 are diagrams showing the same embodiment. FIG. 5 is a flowchart showing the EGR control processed according to the example, FIG. 5 is a flowchart showing a modification of FIG. 4, and FIG. 6 is a graph explaining the EGR operation. A...Diesel engine B...Intake passage C...
Exhaust passage D...Recirculation passage E...First on-off valve F...Second on-off valve G...Operating state detection means

Claims (1)

[Claims] A first on-off valve provided in a recirculation passage communicating an intake passage and an exhaust passage of a diesel engine and capable of adjusting an amount of exhaust gas recirculation; and a first on-off valve provided in the recirculation passage and responsive to an electric signal. a second on-off valve that opens and closes the recirculation passage; an operating state detection means that detects various operating states including at least a load state of the diesel engine; 1st based on
a first control means for controlling the opening degree of the on-off valve; and a second control means for controlling the second on-off valve to be fully closed when it is determined that the load detected by the operating state detection means has changed by a predetermined amount or more. 2. An exhaust gas recirculation control device for a diesel engine, characterized by comprising: