JPS6185563A - Exhaust gas recycling device for engine - Google Patents

Abstract

PURPOSE:To prevent the production of smoke and the increase in the discharged quantity of nitrogen oxides, by providing a means for detecting the opening and closing speed of an accelerator pedal, and an exhaust gas recycling control means for maintaining or ending the recycling stoppage state of an exhaust gas recycling control valve. CONSTITUTION:In a step S5, the opening and closing speed theta of an accelerator pedal is calculated. When the accelerator pedal is sharply closed, steps S6-S8 are taken to set a prescribed time on a timer and keep an exhaust gas recycling valve closed. When the accelerator pedal is slowly depressed after the shifting of a transmission, steps S9, S12, S13 are taken to perform control to open the exhaust gas recycling valve. This results in preventing the production of smoke and the increase in the discharged quantity of nitrogen oxides.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exhaust gas recirculation device for an engine, and particularly to an exhaust gas recirculation device using an angular pressure responsive actuator.

(Conventional technology) In automobile engines, NOx in exhaust gas
In order to reduce the
The exhaust gas recirculation passage generally includes an exhaust gas recirculation passage that communicates the exhaust passage and the intake passage, and an exhaust gas recirculation control valve that is installed on the passage and controls the amount of exhaust gas recirculation. Furthermore, in the case of a diesel engine in which exhaust gas cannot be recirculated to the intake passage using intake negative pressure, for example, Japanese Patent Laid-Open No. 57-414
As shown in Publication No. 53, an intake throttle valve is provided on the upstream side of the opening of the exhaust gas recirculation passage in the intake passage, and the valve is closed during exhaust gas recirculation to generate intake negative pressure. It is designed to ensure that the flow returns to the passageway.

However, as shown in the above publication, the exhaust recirculation control valve and the intake throttle valve are usually driven by a negative pressure responsive type 7 actuator, but this type of actuator outputs the 1lJrD signal. Since the actuator is activated only after the magnitude of the negative pressure changes after that, when this actuator is used, the operation of the exhaust gas recirculation control valve and the like will be delayed.

On the other hand, in a diesel engine, if exhaust gas recirculation is performed at a time of high load with a large amount of fuel supplied, there is a problem in that the combustion state deteriorates and smoke is generated. Therefore, it is customary to perform exhaust recirculation only in the range below a predetermined load, and to stop exhaust recirculation when the predetermined load is exceeded, in relation to the opening degree of the accelerator pedal that controls the injection amount of the fuel injection pump. In that case, due to the delay in the exhaust gas recirculation control valve, the following problems occur, for example, when changing gears.

In other words, as shown in Figure 5, during operation in the exhaust gas recirculation stop area (high load area) where the accelerator pedal opening is 60 degrees or more, the accelerator pedal is once returned to the fully open position for a gear change. , When depressing to the above range again after changing gears, the exhaust recirculation control valve is first activated when the accelerator pedal opening enters lJj air recirculation range (low load range).
It starts to open at 1, and after the gear change, when the accelerator pedal opening enters the exhaust gas recirculation area, it starts to close at 2, but the closing operation is delayed as shown by arrows a and b. Become. Therefore, due to the delay in the closing operation shown by the arrow, exhaust gas recirculation continues for a while even after the engine returns to the 8 load state, and smoke is generated during this time.

(Object of the Invention) The present invention solves the above-mentioned problems in an engine exhaust recirculation device that performs exhaust recirculation at low loads and stops exhaust recirculation at high loads in relation to the opening degree of the accelerator pedal. When the accelerator pedal is released and then pressed again during a gear change, etc., by keeping the exhaust recirculation control valve open from the beginning, the control valve is controlled especially when the accelerator pedal is pressed again. The purpose is to prevent smoke from occurring due to delays in valve closing. In addition, when the accelerator pedal, which is less affected by the delay in the operation of this control valve, is depressed gently, exhaust gas recirculation is performed while the pedal opening is in the exhaust recirculation region, increasing NOx emissions during that time. The purpose is to prevent

(Composition of Light) That is, the present invention includes an exhaust gas recirculation passage and an exhaust gas recirculation control valve that is installed on the passage and controls the amount of exhaust gas recirculation, and has a predetermined load in relation to at least 08 degrees of the accelerator pedal. In an exhaust gas recirculation system for an engine configured to perform exhaust gas recirculation as described below and to stop exhaust gas recirculation when a predetermined load is exceeded, the exhaust gas recirculation device includes a detection means for detecting the opening/closing speed of the accelerator pedal, and a detection means for receiving a signal from the detection means. The exhaust gas recirculation control means controls the operation of the exhaust gas recirculation control valve according to the opening/closing speed of the accelerator pedal when changing gears or the like. The exhaust recirculation control means maintains the exhaust recirculation control valve in the recirculation stop state for a predetermined period of time when the accelerator pedal is returned at a predetermined speed or higher from an exhaust recirculation stop region where the accelerator pedal opening is large; When the accelerator pedal is subsequently depressed, the accelerator pedal operates to release the recirculation stop state of the control valve 114 when the accelerator pedal depression speed is below a predetermined speed. Therefore, if the accelerator pedal is suddenly released during a gear change, the exhaust recirculation control means valve will not open even if the exhaust gas flow reaches the 3rd flow region.
Along with this, when the accelerator pedal is pressed again, the 1TIJ
This prevents smoke from occurring due to a delay in the closing operation of the control valve. In addition, if the accelerator pedal is depressed gently, the closing action of the exhaust recirculation control valve can follow the increase in load, and the time in the antagonistic recirculation region becomes longer. is carried out, and during this period N
This will prevent an increase in Ox emissions.

(Example) Examples of the present invention will be described below.

As shown in FIG. 1, an engine 1 is provided with an intake passage 2 that supplies intake air to the combustion chamber of each cylinder, and an exhaust passage 3 that discharges exhaust gas generated during combustion to the outside. At the same time, an exhaust gas recirculation passage 4 is provided between the exhaust passage 3 and the intake passage 2 to recirculate part of the exhaust gas into the intake passage 2. A control valve (hereinafter referred to as EGR valve) 5 is installed. A negative pressure dial flame type actuator 6 for operating the EGR valve 5 is provided, and a first negative pressure control valve 8 is provided in a negative pressure introducing passage 7 between a negative pressure pump (not shown) and the actuator 6. The EGR valve 5 is automatically controlled by introducing negative pressure into the actuator 6 depending on whether the control valve 8 is opened or closed.

On the other hand, an intake throttle valve 9 is provided on the upstream side of the opening of the exhaust gas recirculation passage 4 in the intake passage 2, and a negative pressure diaphragm type actuator 1o for driving the intake throttle valve 9 to open and close is provided. There is. A second negative pressure control valve 12 is also installed in the negative pressure introduction passage 11 that introduces negative pressure into the actuator 10, and the negative pressure inside the actuator 10 is controlled according to the open/closed state of the control valve 12. Accordingly, the opening degree of the intake throttle valve 9 is controlled.

However, the first negative pressure control valve 8 that controls the EGR valve 5 and the second Q pressure control valve 12 that controls the intake throttle valve 9,
The control unit 13 sends control signals A and 3, respectively, and the control unit 13 also receives a simultaneous rotation signal C from a rotation sensor 15 provided in the fuel injection pump 14, An accelerator opening signal from an accelerator opening sensor 16 that detects the opening of an accelerator pedal linked to the position of the control lever in the pump 14, and a water temperature from a water temperature sensor 17 provided in the water jacket of the engine 1. A signal E is input. Based on these input signals C, D, and E, the 11Jffll signals A and B are outputted according to the continuous operation state of the engine 1. Here, the fuel injection pump 14 pumps fuel to fuel injection nozzles (not shown) installed in each cylinder of the engine 1, and the injection amount depends on the rotational speed of the pump 14 (
It is set according to the engine speed (corresponding to the engine rotation speed) and the accelerator opening.

Next, the operation of this embodiment will be explained according to the flowchart shown in FIG.

First, the control unit 13 receives the water temperature signal E from the water temperature sensor 17 shown in FIG. Based on these signals E, C, Di, :I, it is determined whether the operating state of the engine 1 is in a region where exhaust gas recirculation is performed. In other words, the temperature of the cooling water in the water jacket is, for example, 80°C or higher, the engine speed is within the range of, for example, 900 to 3,000 PPM, and the accelerator pedal opening or the load related to the opening is below a predetermined value. If so, it is determined that the exhaust gas recirculation region exists, and steps 1111ilI from step 85 are performed.

In this control, the control unit 13 calculates the opening/closing speed of the accelerator pedal based on the accelerator opening degree signal in step S5, and then in step S6, the control unit 13 calculates the opening/closing speed of the accelerator pedal when the speed is less than or equal to a predetermined value -9a, that is, when the accelerator pedal is It is determined whether or not it is suddenly closed at a predetermined speed or higher. If the accelerator pedal is not suddenly closed, then in step S7 the EGR valve 5 shown in FIG. 1 is opened and the intake throttle valve 9 is closed. Control signals A and B are sent to the second negative pressure control valve 8.12. As a result, during normal operation in the above-mentioned exhaust gas recirculation region, some exhaust gas is recirculated from the sandwiching passage 3 to the intake passage 2 through the exhaust recirculation passage 4 and the EGR valve 5, and the I) [output of NOx is reduced. It will be reduced.

In this case, as the intake throttle valve 9 closes as described above, the negative pressure in the intake passage 2 around the opening of the exhaust gas recirculation passage 4 increases, thereby ensuring that the exhaust gas is recirculated. Incidentally, if it is determined in step S4 that the exhaust gas is not in the predetermined exhaust recirculation region, the control 2I that listens to the EGR valve 5 is activated.
I (and the control tIl to close the intake throttle valve 9) is not performed, and exhaust gas recirculation is not performed.

On the other hand, when the accelerator pedal is suddenly closed during a gear change, steps S6 to Sa are executed to set a predetermined time To in the timer built in the control unit 13, and the opening/closing speed is checked in step S. It is determined whether the accelerator pedal is pressed again after the accelerator pedal was suddenly closed. Immediately after the accelerator pedal is suddenly closed, the accelerator pedal remains closed because the gear change has not yet been completed, and therefore the opening/closing speed is zero, and the control unit 13 performs the steps S9 to S10. Execute. At this point, the above-mentioned predetermined time To has not elapsed, so step S+1 is further executed, and the EGR
Keep valve 5 closed. As a result, as shown in Fig. 3, even if the accelerator opening changes from the exhaust recirculation stop area to the exhaust recirculation area (■) due to a decrease in the accelerator opening, when the accelerator is suddenly closed and the accelerator opening decreases at a predetermined speed or higher, it is indicated by arrow C. As a result, the EGR valve 5 is not opened and exhaust gas recirculation is not performed. Then, when the gear change is completed and the accelerator pedal is depressed again, the opening/closing speed becomes positive, so the control unit 13 next executes steps S9 to S12, and the depression speed becomes a predetermined value, 6b. Determine whether the value is greater than or not. If it is stepped on rapidly (6>7
3b) to 1j Steps S+o, S as in the above case
Execute ++ and change the time fiII from when the accelerator pedal is suddenly closed.
The EGR valve 5 is kept closed until T exceeds a predetermined value of 115 l1SI TO. Then, the predetermined time To
It returns to normal control when the time has elapsed, but during this time, the accelerator opening degree has already been returned to the IJF air flow reflux area control as shown by the arrow d in Figure 3.
EGR valve 5 is never opened. As a result, even if the engine operating state enters the exhaust recirculation region due to the accelerator pedal being temporarily fully opened during a gear change, if the accelerator pedal is pressed rapidly after the gear change, the exhaust gas No reflux takes place.

It will be bad. Therefore, when exhaust gas recirculation is performed during a gear change as shown by the chain line in FIG. 3, the closing operation of the EGR valve 5 is delayed when the accelerator pedal is depressed again, and ) Even after entering H, the generation of smoke due to exhaust gas recirculation is prevented.

On the other hand, if the accelerator pedal is pressed gently after the gear change (0<b<Mb>), the control unit 13 executes steps 89 N S 12 to S 13 and listens to the EGR valve 5. to control.

In other words, in this case, as shown in FIG. 4, even before the elapse of the predetermined time To, the EG
When the R valve 5 begins to open and the accelerator opening enters the exhaust gas recirculation stop region (2), it begins to close. In this case as well, due to the delay in the opening operation of the EGR valve 5, exhaust gas recirculation will continue for a while even after entering the exhaust recirculation stop area, but in this case, as shown by arrow e, the accelerator opening Since the rate of increase in the load, that is, the rate of increase in the load, is slow, the EGR valve 5 will be closed before the load becomes significantly high, resulting in the problem of smoke generation due to exhaust gas recirculation under high load conditions. Never. In this case, after entering the exhaust recirculation area ■,
The time T1 until the engine exits becomes longer, and if no exhaust gas recirculation is performed during this time, a large amount of NOx will be emitted. Since exhaust gas recirculation is performed by the three GR valves 5, the problem of NOx emission is also prevented.

The above explanation is for when changing gears, but control units 1 to 13 operate in the same way when the accelerator pedal is operated other than when changing gears, and when the accelerator pedal is depressed rapidly. This prevents the problem of smoke generation due to a delay in the closing operation of the EGR valve 5. Furthermore, the present invention is applicable not only to diesel engines but also to other engines that perform similar exhaust recirculation υ.

(Effects of the Invention) As described above, according to the present invention, in the exhaust gas recirculation Hitf of an engine in which exhaust gas recirculation is performed or stopped in relation to the opening degree of the accelerator pedal, the accelerator pedal after a gear change, etc. This prevents smoke from occurring due to the exhaust gas recirculation being interrupted when the engine is pressed down rapidly. Also, if the IC% accelerator pedal is pressed warmly, exhaust gas flow is performed while in the exhaust recirculation region, and NO
This prevents the discharge m of x from increasing.

[Brief explanation of the drawing]

Figures 1 to 4 show embodiments of the present invention. Figure 1 is a control system diagram, Figure 2 is a flowchart diagram showing the operation, and Figures 3 and 4 are exhaust gas recirculation during gear changes, etc. FIG. 5 is a time chart diagram showing conventional problems. DESCRIPTION OF SYMBOLS 1... Engine, 4... Exhaust recirculation passage, 5... Exhaust recirculation control valve (EGR valve), 13... Exhaust recirculation control means (control unit), 16... Accelerator pedal opening/closing speed detection means (Accelerator opening sensor).

Claims (1)

[Claims] (1) It has an exhaust gas recirculation passage and an exhaust gas recirculation control valve that is installed on the passage and controls the amount of exhaust gas recirculation, and performs exhaust gas recirculation at a predetermined load or less in accordance with at least a signal related to the accelerator pedal opening. In an engine exhaust recirculation device configured to stop exhaust recirculation when a predetermined load is exceeded,
A detecting means for detecting the opening/closing speed of the accelerator pedal is provided, and when the accelerator pedal is returned from the exhaust gas recirculation stop area at a predetermined speed or higher, the exhaust recirculation control valve is held in the recirculation stop state for a predetermined period of time, and thereafter An exhaust gas recirculation device for an engine, comprising an exhaust recirculation control means for releasing the recirculation stop state of the exhaust recirculation control valve when the accelerator pedal is depressed and the accelerator pedal is depressed at a predetermined speed or less.