JPH02169853A - Exhaust gas re-circulation controlling device - Google Patents

Abstract

PURPOSE:To repress the generation of NOX and prevent the generation of HC, CO, smoke, etc., by installing an exhaust gas re-circulation valve for an engine, a suction throttle valve on a suction pipe and a controlling means to control the said re-circulation valve and the throttle valve. CONSTITUTION:An exhaust gas re-circulation valve 7 for an engine 1 and a suction throttle valve 6 on a suction pipe 2 are installed. A controller 14 controls the re-circulation valve 7 and the throttle valve 6 in accordance with the output of an acceleration sensor 5 and an engine revolution sensor 4. When an idle condition was detected from the output of the acceleration sensor 5, the re- circulation valve 7 and the throttle valve 6 are held immobile for a specified period of time, which makes it possible to repress the generation of NOX contained in exhaust gas and to prevent the generation of HC, CO, smoke, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an exhaust gas recirculation (EGR) control device;
In particular, the present invention relates to an exhaust gas recirculation control device that controls an engine exhaust gas recirculation valve and an intake throttle valve installed in an intake pipe in accordance with the accelerator opening degree and engine speed to provide an optimal GRI.

[Conventional technology]

EGr aimed at reducing NOx in exhaust gas
? Control has been widely used in the past, especially E C)
? If you want to increase l, or if you have a turbocharged engine and it is difficult to apply the GR, you may use an intake throttle.

An example of such a conventional exhaust gas recirculation device is shown in FIG. 1, where l is an engine, 2 is an intake pipe of engine l, 3 is an exhaust pipe of engine 1, and 4 is a rotation speed sensor of engine l. , 5 is an accelerator sensor that detects the opening degree of the accelerator (not shown), 6 is an intake throttle valve provided in the intake pipe 2, 7 is an exhaust gas recirculation valve, and 8 is a sensor that detects the pressure downstream of the intake throttle valve. A pressure sensor 9 detects the diaphragm pressure of the exhaust gas recirculation valve 7; 10 and 11 control the opening and closing of the intake throttle valve 6 and the recirculation valve 7 using negative pressure from a vacuum pump (VP) 12; Solenoid valve (
13 is an EGR pipe, 14 is a controller as a control means, and 15 is a turbocharger that uses the exhaust gas flow to drive a turbine 15a, compresses air from an air cleaner 16, and sends it to the intake pipe 2 side. It is.

The operation of this exhaust gas recirculation device will be explained with reference to the flowchart shown in FIG.

First, the controller 14 reads the engine speed signal and accelerator opening signal sent from the engine speed sensor 4 and the accelerator sensor 5 (step 3 in FIG. 3).
1).

From these data, the target values of the intake pipe pressure and EGR diaphragm pressure for the intake throttle valve 6 and the exhaust gas recirculation valve 7 are determined, and the duty ratios of 5vlO and 11 are controlled (step S2).

This target value determination is performed based on the map shown in FIG. 4, which is stored in advance in the controller 14, and the intake pipe pressure is determined by (a) in the same figure, and the EGR diaphragm pressure is determined by Φ) in the same figure. .

In order to see the results of this control, the controller 14 detects the pressures of the intake throttle valve 6 and the exhaust gas recirculation valve 7 through a pressure sensor 8.
and 9 (Step S3), and from the results calculate the amount of change in the duty ratio of each VSV 10 and 11 (Step S4), the diaphragm pressure of the intake throttle valve 6 and the exhaust gas recirculation valve 7 is The controller 14 performs control to approach the target value by changing the duty ratio.

With such conventional exhaust gas recirculation devices, although the NOx emissions during idling operation are low, they remain in the idling state for a long time, so in order to satisfy emission regulations, EGR should be used as much as possible. You need to spend a lot.

Therefore, in the idle state, the intake throttle valve is throttled and the exhaust gas recirculation valve is opened as shown in FIG.

By the way, when shifting up to perform acceleration operation under such map control, the accelerator is released once and the clutch is disengaged, so the engine is in an idle state and the intake throttle valve 6 is throttled as described above to reduce exhaust gas. Since control is performed to open the recirculation valve 7, the inflow of fresh air is reduced, and as described above, in the case of a turbocharged engine, the inlet pressure of the turbine 15a is reduced. Then, when the driver shifts up, engages the clutch, and depresses the accelerator, the intake throttle valve 6 approaches the open state and the exhaust gas recirculation valve 7 approaches the closed state.

In other words, when shifting up, the engine is temporarily in an idle state, and ■
Because the amount of intake air had decreased, ■ the turbine inlet pressure had decreased, and ■ the amount of gas flowing into the turbine had decreased due to the decrease in intake air, the intake air remained transient even when the accelerator was pressed after upshifting. In addition, the supercharging of the turbocharger 15 is also delayed. These two delays mutually affect each other, resulting in a significant intake air response delay.

On the other hand, the amount of fuel is increased by stepping on the accelerator regardless of these factors, resulting in combustion that lacks air, resulting in HC,
This will increase the emissions of Co, smoke, etc.

To solve this problem, the following conventional techniques have been proposed.

(1) In the device disclosed in Japanese Patent Application Laid-Open No. 61-85563, when the accelerator is rapidly closed at a predetermined speed or higher, the exhaust gas recirculation valve is opened for a predetermined period of time, so that the engine is brought back to idle operation. Even if the condition occurs, EGR is not applied.

(2) In the device disclosed in Japanese Patent Application Laid-open No. 57-41437, the operation of the intake throttle valve is delayed only when the accelerator is released and the fuel injection amount decreases, so that the opening corresponds to the fuel injection amount. It is controlled to maintain a larger opening.

[Problem to be solved by the invention]

Conventional examples (1) and (2) as described above had the following problems.

With the device (1), since the exhaust gas recirculation valve is closed, EGR is not applied even when the engine is in idle mode, so when the accelerator is pressed again, the generation of HC9Co, smoke, etc. can be prevented, but for a specified period of time. NOx will be generated inside.

In the device (2), the operation of the intake throttle valve is delayed even when changing gears, so NOx is generated during this time.

Also, when you slowly release the accelerator and then press it down quickly, there is a time delay caused by the delay circuit, which causes a delay in the supply of fresh air, causing EGR to be applied even if the engine is at high speed and there is no need for EGR. become.

(Means for Solving the Problems) In order to achieve the above object, an exhaust gas recirculation device according to the present invention includes an engine exhaust gas recirculation valve, an intake throttle valve installed in an intake pipe, and an accelerator sensor. , an engine rotation speed sensor, and the recirculation valve and throttle valve are controlled according to the outputs of both sensors, and when an idle state is detected from the output of the accelerator sensor, the recirculation valve and the throttle valve are controlled for a predetermined period of time. and control means for immobilizing the throttle valve.

[For production]

In the present invention, the control means normally controls the exhaust gas recirculation valve and the intake throttle valve according to the outputs of the accelerator sensor and the engine speed sensor.

However, when the control means detects that the engine is in an idle state from the output of the accelerator sensor, it does not change the intake pressure and the target value of EGRI for a predetermined period of time before the accelerator is closed, so the exhaust gas recirculation valve and Maintains the opening of the intake throttle valve and makes it immobile.

Therefore, the lack of intake air during upshifting can be eliminated, thereby preventing the discharge of HCSCo, smoke, etc., and at the same time preventing the generation of NOx during upshifting.

As a result, even if the vehicle is in an idling state during a gear change operation, a constant EGR can be applied, and NOx can be reduced.

【Example〕

One embodiment of the exhaust gas recirculation control device according to the present invention can use the configuration shown in FIG. 1 described above.

However, an example of a program stored and executed in the controller 14 as the WIjT1 means is shown in FIG.

Embodiments of the present invention will be described below with reference to the flowchart shown in FIG. Incidentally, the same steps as in FIG. 3 are given the same reference numerals and their explanations will be omitted.

First, in step S1 of FIG. 2, the controller 14 reads the engine rotation speed signal and the accelerator opening signal sent from the engine rotation speed sensor 4 and the accelerator sensor 5, and then the accelerator position is determined to be idle based on the accelerator opening signal. It is determined whether or not the position is reached (step 5ll in FIG. 2).

As a result of this determination, if it is not in the idle position, the timer count based on the clock of the controller 14 is cleared (step 312), and steps 82 to S5 similar to those in FIG. 3 are executed.

As a result of the determination, if the accelerator has returned to the idle position, the timer count is compared with the predetermined time T1 (Step 513), and if the timer count≦the predetermined time T1, it is checked whether the timer count is −0 or not (Step 5).
14) When timer count>predetermined time T, the process advances to step S2.

When the timer count=0 in step 314, the timer count is started (step 515), and when the timer count≠0, the process advances to step S3.

That is, the timer count is always cleared in the non-idle state (step 312), and is started through step S13.314 only when the non-idle state changes from the idle state (step 515). Thereafter, a timer count is continued in the controller 14, and when the timer count reaches -T1, EGR control is continued (steps 82 to S5).

Therefore, the determination and control of the target values for the intake pipe pressure and EOR diaphragm pressure (step 32) are not executed until the predetermined time T1 has elapsed after the accelerator enters the idle state, and the target values immediately before the accelerator enters the idle state are not executed. Based on this target value without changing, EGRIII similar to that shown in FIG.
m will be performed.

〔Effect of the invention〕

As described above, in the exhaust gas recirculation control device according to the present invention, when an idle state is detected from the output of the accelerator sensor, the exhaust gas recirculation valve and the intake throttle valve are kept immobile for a predetermined period of time. With this configuration, the generation of NOx contained in exhaust gas can be suppressed, and since the intake throttle valve and exhaust gas recirculation valve have a certain degree of opening, even in the idling state, EGR and when the accelerator is pressed again can be controlled. It is possible to prevent the generation of HC, CO, smoke, etc. due to lack of fresh air.

[Brief explanation of the drawing]

Fig. 1 is a system configuration diagram of an exhaust gas recirculation control device common to the present invention and the conventional example, Fig. 2 is a flowchart of a program executed by the control means of the present invention, and Fig. 3 is a conventional FIG. 4 is a flowchart of the program executed by the control means, and is a map diagram that graphically shows the intake pipe internal pressure and EGR diaphragm pressure that are set according to the engine speed and the accelerator opening.

Claims (1)

[Claims] An exhaust gas recirculation valve of the engine, an intake throttle valve installed in the intake pipe, an accelerator sensor, an engine rotation speed sensor, and the recirculation valve and the throttle valve are controlled according to the outputs of both sensors, and the accelerator sensor An exhaust gas recirculation control device comprising: control means for immobilizing the recirculation valve and the throttle valve for a predetermined period of time when an idle state is detected from the output of the exhaust gas recirculation control device.