JPS63109281A - Ignition timing control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent the reduction in torque and the worsening in emission or the like, by correcting the spark advance value in the direction in which the ignition timing is delayed, when the differential pressure between the atmospheric pressure and the intake air pressure is less than the operating pressure of an exhaust gas recirculation control valve, so that the exhaust gas recirculation is not carried out. CONSTITUTION:On the basis of the detected value of a pressure sensor 13 being commonly used for the atmospheric pressure detecting means and for the intake pressure detecting means by the changeover control of a changeover valve 14, if the differential pressure between the atmospheric pressure and the intake air pressure is greater than the operating pressure of an EGR valve 8, the EGR valve 8 is operated to carry out the exhaust gas recirculation. In this case, the final spark advance value is set on the basis of the basic spark advance value calculated by the detected values of various sensors and the like, so that an ignition plug 25 is electrified. On the other hand, when the differential pressure between the atmospheric pressure and the intake air pressure is less than the operating pressure of the EGR valve 8, the EGR valve 8 is not operated, and an EGR correction value is added to the basic spark advance value, and the final spark advance value is set in the direction in which the ignition timing is delayed. Accordingly, an optimum ignition timing conforming to the combustion speed outside the execution area of the EGR is set. Thus, the reduction in torque and the worsening in emission or the like can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ignition timing control device for an internal combustion engine suitably used in automobiles and the like equipped with an exhaust gas recirculation control valve.

[Prior Art] Generally, in an automobile engine, in order to reduce the generation of NOx contained in exhaust gas, an intake system and an exhaust system are communicated through an exhaust gas recirculation passage (hereinafter referred to as an EGR passage).
An exhaust gas recirculation control valve (hereinafter referred to as an EGR valve) is interposed in this EGR passage to perform so-called EGR control in which part of the exhaust gas is recirculated to the intake system to suppress the maximum combustion temperature.

In addition, in order to efficiently purify exhaust gas with a three-way catalyst installed in the exhaust system, the amount of fuel supplied to the intake system is adjusted to maintain the air-fuel ratio near the stoichiometric air-fuel ratio. There is. At this time, the amount of fuel supplied is usually set so that the air-fuel ratio becomes approximately the stoichiometric air-fuel ratio in a state where exhaust gas recirculation is performed.

On the other hand, in the ignition system, in order to obtain the optimal ignition timing according to the engine rotation speed or the combustion speed of the fuel supplied to the combustion chamber, for example, a centrifugal advance device built in the distributor or a vacuum The ignition timing is controlled by adjusting the advance value of a type advance device or the like. When the above-mentioned EGR is executed, the combustion speed of the fuel decreases, so when setting the ignition timing, the EGR
Generally, the ignition timing is slightly advanced to match the combustion speed of the fuel during R execution. Furthermore, as shown in Japanese Unexamined Patent Publication No. 59-32672, there is also a system in which the ignition timing is corrected in accordance with fluctuations in the exhaust gas recirculation rate.

[Problems to be Solved by the Invention] However, the EGR control is mechanical using an EGR valve that is activated when the differential pressure between atmospheric pressure and intake pressure exceeds a substantially set value. In other words, part of the exhaust gas is recirculated into the intake air when the differential pressure between atmospheric pressure and intake pressure exceeds the operating pressure of the EGR valve, and EGR is constantly being performed while the engine is running. However, there are regions where EGR is not being performed due to the differential pressure between atmospheric pressure and intake pressure. However, the amount of fuel supplied to the intake system is set so that the air-fuel ratio becomes the stoichiometric air-fuel ratio, assuming that exhaust gas is mixed in the intake air, so the amount of fuel supplied to the intake system is set so that the air-fuel ratio becomes the stoichiometric air-fuel ratio. In this case, the control center of the air-fuel ratio shifts from the stoichiometric air-fuel ratio because the exhaust gas is not recirculated to the intake air, and the combustion speed of the fuel increases. Therefore, outside the EGR execution range, the ignition is not performed at the optimum ignition timing, and the torque decreases, causing problems such as deterioration of emissions.

An object of the present invention is to provide an ignition timing control device for an internal combustion engine that can easily and reliably eliminate such problems.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an internal combustion engine equipped with an exhaust gas recirculation control valve that operates based on the differential pressure between atmospheric pressure and intake pressure. an atmospheric pressure detection means for detecting the intake pressure, an intake pressure detection means for detecting the intake pressure, and a differential pressure between the atmospheric pressure and the intake pressure based on the detected values by both the detection means exceeds the operating pressure of the exhaust recirculation control valve. differential pressure determining means for determining whether the differential pressure is lower than the operating pressure; and an advance for correcting the advance value in the direction of retarding the ignition timing only when the differential pressure determining means determines that the differential pressure is lower than the operating pressure. It is characterized in that it is provided with an angle value correction means.

[Operation] According to this configuration, the operating state of the exhaust gas recirculation control valve is determined by detecting the atmospheric pressure and the intake pressure, which directly influence the operating state of the valve. That is, based on the detected values from the atmospheric pressure detection means and the intake pressure detection means,
The differential pressure determining means determines whether the differential pressure between the atmospheric pressure and the intake pressure exceeds the operating pressure of the exhaust recirculation control valve. If the differential pressure between atmospheric pressure and intake pressure exceeds the operating pressure of the exhaust recirculation control valve and exhaust recirculation is being performed,
If the previous ignition timing is set and, on the other hand, the differential pressure is lower than the operating pressure and exhaust gas recirculation is not being performed, the advance value is corrected by the advance value correction means in a direction that retards the ignition timing. become.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

Figure 2 schematically shows an automobile engine.
In the drawings, 1 indicates an engine body, 2 an intake passage communicating with a combustion chamber 3 of the engine body 1, and 4 an exhaust passage. An intake pipe 5 forming the combustion chamber 3 side of the intake passage 2
A surge tank 6 is interposed between the throttle body and the throttle body disposed on the air cleaner side. The inside of this surge tank 6 and the inside of the exhaust passage 4 are communicated through an exhaust gas recirculation passage 7, and an exhaust gas recirculation control valve (hereinafter referred to as 8 (referred to as an EGR valve) is installed. EGR
The valve 8 is for guiding a part of the exhaust gas in the exhaust passage 4 into the surge tank 6 interposed in the intake passage 2 by opening the valve according to the operating condition of the engine. Intake pressure PM is transferred to the negative pressure chamber 8a through a negative pressure passage 10 that communicates with the EGR port 9 near the throttle valve.
is being introduced. On the other hand, this negative pressure chamber 8a
Atmospheric pressure PA is always introduced into a constant pressure chamber 8b provided with a diaphragm in between. and,
The differential pressure between the atmospheric pressure PA and the intake pressure PM guided to the negative pressure chamber 8a is the EGR valve operating pressure PEGRV (for example, 10
0 mmHg), the EGR valve 8 opens and a portion of the exhaust gas in the exhaust passage 4 is introduced into the surge tank 6. Further, an EGR modulator 11 is interposed in the middle of the negative pressure passage 10, and an EGR valve 8
Using the exhaust pressure in the exhaust gas recirculation passage 7 on the downstream side, the EO
The intake pressure PM introduced into the negative pressure chamber 8a of the R valve 8 is adjusted, and the intake pressure PM acting on the negative pressure chamber 8a of the EGR valve 8 is arranged on the upstream side of the EGR modulator 11. An electronic negative pressure switching valve 12 is provided to limit the pressure in the engine's low load range.

Further, on the surge tank 6 side, a common pressure sensor 13 is provided as an atmospheric pressure detection means for detecting the atmospheric pressure PA and an intake pressure detection means for detecting the intake pressure PM. The pressure sensor 13 is connected to the outside air and the surge tank 6 via the switching valve 14.
It is possible to selectively connect to the inside and outside. Specifically, the switching valve 14 is substantially the same as the negative pressure switching valve 12, and is a vacuum switching type three-way switching valve.
The first input port 14a is communicated with the inside of the surge tank 6, the second input port 14b is opened to the outside air via a filter, and the output port 14C is connected to the pressure sensor 13. When the electrical input terminal is not energized, the intake pressure is held at the PA side and the first input port 14a and the output port 14c communicate with each other, and when the electrical input terminal is energized. In this case, the second input port 14b and the output port 14c are configured to communicate with each other by switching to the atmospheric pressure PA side.

On the other hand, a microcomputer system 16 that finely controls the amount of fuel injection from the injector 15 provided in the intake pipe 5 according to the operating condition of the engine is based on information from the 02 sensor 17 provided in the exhaust passage 4. The central processing unit 20 plays a role in so-called 02 feedback control, which maintains the air-fuel ratio near the stoichiometric air-fuel ratio. , a memory 21, and input/output interfaces 22 and 23. Then, at least the signal a from the =7-02 sensor 17 and the signal from the pressure sensor 13 are input to the input interface 22, and the injector 15, the negative pressure switching valve 12, and the output interface 23 are input to the input interface 22. , signals cSd, e to the switching valve 14 and the actuator 24.
, f are output. Actuator 2
Reference numeral 4 operates an advance angle adjustment section (not shown) in a distributor 26 that guides electricity to a spark plug 25 in response to an input signal.

The differential pressure determining means 18 is configured to control the pressure sensor 13 by selectively switching the switching valve 14 between the outside air side and the intake side.
The differential pressure between the atmospheric pressure PA and the intake pressure PM obtained from the above E
It is set to determine whether or not the GR valve operating pressure exceeds PEGRV (100 mmHg).

On the other hand, the advance angle value correction means 19 constituted by the actuator 24 and the microcomputer system 16 determines that the differential pressure between the atmospheric pressure PA and the intake pressure PM is equal to the EGR valve operating pressure PEGRV based on the determination result of the differential pressure determination means 18. Only when the value is less than , the advance angle adjustment section in the distributor 26 is operated to retard the ignition timing to correct the advance value. That is, atmospheric pressure PA
The difference between the pressure and the intake pressure PM is the EGR valve operating pressure PEGRV.
If EGR is in progress, the basic advance angle values TH, TB
The final lead angle value THT is set based on SE, etc. on the other hand,
If the differential pressure between the atmospheric pressure PA and the intake pressure PM is lower than the EGR valve operating pressure PEGRV and EGR is not being executed, the basic advance value Tl1TBSE is set to EGR outside the EGR execution area.
The final advance value THT is set in the direction of retarding the ignition timing by adding a GR correction value THTEGR (for example, a value shifted by 18 degrees to the retard side with respect to the top dead center of the crank angle).

The microcomputer system 16 includes:
In order to perform the above control, a program as shown in FIG. 4 is also included. First, in step 51, the atmospheric pressure PA from the pressure sensor 13 after switching the switching valve 14 is taken in, and the process proceeds to step 52. In step 52, the intake pressure PM in the surge tank 6 is similarly acquired by the pressure sensor 13, and the process proceeds to step 53. Then, in step 53, a basic advance angle value THTBSE is calculated based on information from, for example, a rotation speed sensor, and the process proceeds to step 54. Step 5
In step 4, it is determined whether the EGR correction execution flag FLAG is 1 or not, and if the EGR correction execution flag FLAG is 1, the process proceeds to step 55, where atmospheric pressure PA and EGR valve operating pressure PEG are determined.
The differential pressure between the RV and the old hysteresis S is set as the EGR correction determination value CMP, and the process proceeds to step 57.

On the other hand, if the EGR correction determination flag FLAG is not 1, the process proceeds to step 56, where atmospheric pressure PA and EGR valve operating pressure PE
Set GRV to CMP as EGR correction determination value CMP. In step 57, it is determined whether or not the intake pressure PM is equal to or greater than the EGR correction determination value CMP.
If it is determined that the intake pressure PM exceeds EGRV, the EGR valve 8 is activated and EGR is executed, and the process proceeds to step 58. On the other hand, if it is determined that the intake pressure PM is greater than or equal to the EGR correction determination value CMP, the EGR valve 8 is activated and EGR is executed. It is determined that the process has not been executed, and the process proceeds to step 59. In step 58, the EGR correction determination flag FLAG is set (cleared) to 0, and the process proceeds to step 60. In step 60, the step 53
Based on the basic advance angle value THTBSE calculated in
Sets the final advance angle value THT during EGR execution. On the other hand, in step 59, the EGR correction determination flag FLAG is set to 1, and the process proceeds to step 61. In step 61, the basic advance angle value TIITBSE is set to the EGR correction value T during EGR execution.
The final lead angle value THT is set based on the value to which IITEGR is added.

According to such a configuration, it is possible to determine whether or not the EGR valve 8 is operating based on the detected value from the pressure sensor 13 obtained by switching control of the switching valve 14, in other words, it is possible to determine whether or not the EGR valve 8 is operating. It is determined whether part of the air is being refluxed during inspiration. In other words, if the differential pressure between atmospheric pressure PA and intake pressure PM exceeds the EGR valve operating pressure PEGR, the EGR
This means that the R valve 8 is activated and exhaust gas recirculation is being performed. In that case, the final lead angle value T
HT is set, and electricity is led to the spark plug 25 based on this value (steps 57→58-60).

On the other hand, if the differential pressure between the atmospheric pressure PA and the intake pressure PM is less than the operating pressure PEGRV of the EGR valve 8, the EGR valve 8 does not operate and exhaust gas recirculation is not performed. In that case, the EGR correction value TII is added to the basic advance angle value THTBSE.
The final advance value THT is set in the direction of retarding the ignition timing by adding TEGR etc. (Step 57→
59 → 61).

Therefore, with such a configuration, the pressure sensor 13
It is possible to reliably determine whether or not EGR is being executed based on the information from the engine, and also to set the optimum ignition timing that matches the combustion speed outside the EGR execution range.

As a result, ignition is performed at the optimum ignition timing even outside the EGR execution range, so it is possible to prevent drivability from being impaired due to a decrease in output torque. In addition, since the differential pressure between the atmospheric pressure PA and the intake pressure PM is a relative value detected by the pressure sensor 13, the operation of the EGR valve 8 can be reliably detected even if the atmospheric pressure PA fluctuates, and the above-mentioned The lead angle value can be corrected.

In this embodiment, the pressure sensor 1 that is normally installed is
3 is provided with a switching valve 14 so that the pressure detection area of the pressure sensor 13 can be switched between the atmospheric side and the intake side, which is advantageous since there is no need to provide a special pressure sensor.

Note that the present invention is not limited to the above-mentioned embodiments, and for example, the atmospheric pressure detection means and the intake pressure detection means may be provided separately, or the EGR correction value outside the EGR execution area may be may be set depending on the amount of exhaust gas recirculation.

[Effects of the Invention] As detailed above, the present invention directly detects atmospheric pressure and intake pressure, and reliably determines the operating state of the exhaust recirculation control valve without being affected by changes in atmospheric pressure. That's what I do. Then, the advance angle value is corrected according to the operating state of the exhaust gas recirculation control valve to set the optimum ignition timing. As a result, it is possible to provide an ignition timing control device for an internal combustion engine that does not impair driveability even in a region where exhaust gas recirculation is not performed.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the configuration to clarify the present invention, Fig. 2 is an explanatory diagram of a system showing an embodiment of the invention, Fig. 3 is a diagram showing control setting conditions of the embodiment, and Fig. 4 is an explanatory diagram of the system. It is a flowchart figure which shows the control procedure of the same Example. 1... Engine body 2... Intake passage 4... Exhaust passage 6... Surge tank 7... EGR passage 8... EGR valve 10... Negative pressure passage 13... Atmospheric pressure detection Means (pressure sensor) 13...Intake pressure detection means (pressure sensor) 14...Switching valve 16...Microcomputer system 18...Differential pressure determination means 19...Advance value correction means

Claims (1)

[Claims] In an internal combustion engine equipped with an exhaust gas recirculation control valve operated by a pressure difference between atmospheric pressure and intake pressure, an atmospheric pressure detection means for detecting atmospheric pressure, an intake pressure detection means for detecting intake pressure, and both detection means are provided. differential pressure determining means for determining whether the differential pressure between the atmospheric pressure and the intake pressure exceeds the operating pressure of the exhaust recirculation control valve based on a value detected by the means; 1. An ignition timing control device for an internal combustion engine, comprising: an advance angle value correcting means for correcting an advance angle value in the direction of retarding the ignition timing only when it is determined that the ignition timing is lower than the operating pressure.