JPS6052297B2 - engine control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides control of an engine equipped with an exhaust gas recirculation device that recirculates part of the exhaust gas emitted from the engine from the exhaust system to the intake system to suppress the generation of NOx. This relates to improvements in equipment.

Generally, in an exhaust gas recirculation device that is used as a part of an engine control device, when part of the exhaust gas is recirculated from the exhaust system to the intake system through the recirculation passage, an exhaust recirculation valve is installed in the recirculation passage. The amount of recirculation of exhaust gas is controlled according to the operating state of the engine.

In addition, recirculation of exhaust gas has a negative effect on engine drivability, fuel efficiency, etc., so in order to always recirculate the optimal amount, for example, as in Japanese Patent Application Laid-Open No. 53-107526, engine load, engine rotation speed, etc. Various types of exhaust gas recirculation devices, such as electronically controlled exhaust gas recirculation devices, are now being adopted, which detect the operating state of the engine by detecting the engine, and use a control device to feedback-control the exhaust gas recirculation valve to the optimal recirculation amount for this operating state. It's summery. However, in the above-mentioned exhaust gas recirculation system, there are cases where the exhaust recirculation valve becomes open due to malfunction of the exhaust recirculation valve operating system, malfunction of the control device, etc., and more exhaust gas than the set recirculation amount is recirculated. be. In this way, if more exhaust gas is recirculated than the amount required for the engine operating condition,
The drivability of the engine is significantly reduced, resulting in problems such as poor starting, poor idling, and insufficient output. Therefore, when the exhaust gas recirculation valve becomes open due to an abnormality in the exhaust gas recirculation device, the present invention detects this and stops the recirculation of exhaust gas, eliminates the permanent state caused by excessive recirculation of exhaust gas, and improves drivability. It is something that must be ensured.

Therefore, the air-fuel ratio or ignition timing of the engine is determined and controlled depending on the operating conditions such as engine speed and load. Depending on the amount of exhaust gas recirculation, it is controlled in advance to enrich the air-fuel ratio or advance the ignition timing, and if exhaust gas recirculation is stopped in the event of an abnormality as described above, The air-fuel ratio or ignition timing, which is determined and controlled based on the assumption that a set amount of fuel is being recirculated, will not match the operating conditions of the engine, resulting in a decrease in fuel efficiency and the occurrence of knocking.

In view of the above, the present invention provides an exhaust gas recirculation device including an exhaust gas recirculation valve that extracts a portion of exhaust gas from the exhaust system and recirculates it to the intake system, and an exhaust gas recirculation device that takes out part of the exhaust gas from the exhaust system and recirculates it to the intake system, and an exhaust gas recirculation device that takes out a part of exhaust gas from the exhaust system and recirculates it to the intake system. a control circuit that determines and controls according to an exhaust gas recirculation amount set correspondingly to the exhaust gas recirculation amount; an abnormality detection device that detects an open state of the exhaust gas recirculation valve caused by an abnormality of the exhaust gas recirculation device; an exhaust gas recirculation stop device that receives the output from the abnormality detection device and stops the recirculation of exhaust gas; and a correction device that receives the output from the abnormality detection device and corrects the air-fuel ratio or ignition timing to a value that does not take into account the amount of exhaust gas recirculation. Provides engine control equipment,
This aims to improve fuel efficiency, etc. when exhaust gas recirculation is stopped.

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, reference numeral 1 denotes an intake system for supplying intake air to an engine (not shown), and the flow rate of intake air flowing through an intake passage 2 is controlled by a throttle valve 3. Reference numeral 4 refers to a recirculation passage that recirculates exhaust gas from an exhaust system (shown in the figure) connected to the engine to the intake system 1 (intake passage 2 downstream of the throttle valve 3); 5 refers to the recirculation passage 4;
This is an exhaust gas recirculation valve of the exhaust gas recirculation device 6 installed in the exhaust gas recirculation device 6.

The exhaust gas recirculation valve 5 includes a diaphragm 5c to which a valve body 5a for opening and closing the recirculation passage 4 is attached via a rod 5b, a negative pressure chamber 5d and an atmospheric chamber 5e partitioned by the diaphragm 5c, and the valve The negative pressure acting on the negative pressure chamber 5d is used as an opening source, and this negative pressure biases the diaphragm 5c against the spring force of the spring 5f. It is configured to open the valve body 5a and control the amount of recirculation of exhaust gas according to the amount of movement of the valve body 5a.

A negative pressure passage 7 is communicated with the negative pressure chamber 5d of the exhaust gas recirculation valve 5, and one end 7a of the negative pressure passage 7 is connected to the intake passage 2 downstream of the throttle valve 3.
The other end 7b is opened to the atmosphere via the negative pressure solenoid valve 8 and the atmospheric solenoid valve 9, and the negative pressure passage 7 between the negative pressure solenoid valve 8 and the atmospheric solenoid valve 9 is connected to the negative pressure chamber. 5d.

The negative pressure and atmospheric solenoid valves 8 and 9 are controlled by a control circuit 10.
It is opened and closed for a predetermined time by a control signal from the exhaust recirculation valve 5 to adjust the negative pressure chamber 5d of the exhaust gas recirculation valve 5 to a predetermined pressure and control the amount of movement of the valve body 5a. In addition, 11 is the intake passage 2 upstream of the throttle valve 3.
The fuel injection device 11 is operated by a control signal from a control circuit 10 via a correction device 12, and is controlled to achieve a predetermined air-fuel ratio.

On the other hand, reference numeral 13 denotes an ignition device. A control signal from the control circuit 10 via the correction device 12 is also input to the ignition device 13, and the ignition device 13 is controlled to ignite at a predetermined ignition timing.

Furthermore, 14 is a rotation sensor that detects the engine rotation speed, 15 is a negative pressure sensor that detects the intake negative pressure downstream of the throttle valve 3, and 16 is a valve element attached to the exhaust recirculation valve 5 that detects the moving position of the valve element 5a. The detection signals of each of the position detection sensors are input to the control circuit 10, respectively.

The control circuit 10 moves the valve body 5a of the exhaust gas recirculation valve 5 to a target value corresponding to an optimal exhaust gas recirculation amount determined through experiments in response to an engine operating state based on an arbitrary combination of intake negative pressure and engine speed. This control circuit 10 controls the exhaust recirculation valve 5 by outputting a control signal to the negative pressure and atmospheric solenoid valves 8 and 9 so that the target movement amount of the valve body 5a coincides with the target movement amount of the valve body 5a. It is configured to perform exhaust gas recirculation control according to the current operating state.

The control circuit 10 also controls the engine operating state based on an arbitrary combination of intake negative pressure and engine speed, and the optimum exhaust gas recirculation amount (target movement amount of the valve body 5a) that is set corresponding to this engine operating state. ), the optimum air-fuel ratio and ignition timing determined through experiments are stored in advance, and the control circuit 10 controls the fuel injection device 11 and the ignition timing to perform fuel injection and ignition at this optimum air-fuel ratio and ignition timing. It is configured to control the ignition device 13. Next, reference numeral 17 denotes an abnormality detection device for detecting an open state of the exhaust gas recirculation valve 5 caused by an abnormality in the exhaust gas recirculation device 6. A signal of the amount of movement and a signal of the measured amount of movement of the valve body 5a from the valve body position detection sensor 16 are input.

This abnormality detection device 17 compares both the above signals and detects the valve body 5a.
When the measured amount of movement does not match the target amount of movement even after a set time has elapsed and remains in the open state, a detection operation is activated and an output signal is generated. The exhaust gas recirculation stop device 18, which receives the output of the abnormality detection device 17 and stops the recirculation of exhaust gas, includes a shutoff valve 18a that closes off the recirculation passage 4 upstream of the exhaust recirculation valve 5, and When the abnormality detection device 17 detects that the exhaust gas recirculation valve 5 is in an abnormally open state, that is, that exhaust gas is excessively recirculated, the recirculation passage 4 is configured to close and stop the recirculation of exhaust gas.

Further, the output of the abnormality detection device 17 is also output to the correction device 12, and when the abnormality detection device 17 detects an abnormal open state of the exhaust recirculation valve 5, the correction device 12 controls the fuel injection device 11 and the ignition device 13. The control signal from the control circuit 10 is corrected so that the air-fuel ratio and ignition timing become the optimum air-fuel ratio and ignition timing for the engine operating condition in which exhaust gas recirculation is not performed. It is configured to correct to a value that does not take into account the amount of gas recirculation (leaner air-fuel ratio, retarded ignition timing). To explain the operation of the above embodiment, the control circuit 10 receives the rotation speed signal from the rotation sensor 14 and the negative pressure sensor 1.
In combination with the negative pressure signal from 5, the target movement amount of the valve body 5a corresponding to the optimum exhaust gas recirculation amount according to the current operating condition is calculated from the map in the memory device, and this target movement amount and the valve body position are calculated. The amount of movement actually measured from the detection sensor 16 is compared, and a control signal corresponding to the difference is output to the negative pressure and atmospheric solenoid valves 8 and 9, and the solenoid valves 8 and 9 are opened and closed for a predetermined period of time.

A predetermined negative pressure is introduced into the negative pressure chamber 5d of the exhaust gas recirculation valve 5 according to the opening and closing times of the negative pressure solenoid valve 8 and the atmospheric solenoid valve 9, and the valve body 5a is operated to a target movement amount to open the recirculation passage 4.
This is to suppress the generation of exhaust gas by recirculating a predetermined amount of exhaust gas according to the current operating state. In addition, the control circuit 10
calculates the optimal air-fuel ratio and ignition timing when the optimum exhaust gas recirculation amount is recirculated based on the engine operating state based on the engine speed and intake negative pressure, and outputs a control signal corresponding to this to the fuel injection device 11. and is output to the ignition device 13 to perform fuel injection and ignition with predetermined air-fuel ratio and ignition timing characteristics.

Next, when there is an abnormality in the exhaust gas recirculation device 6, for example, the negative pressure or atmospheric solenoid valves 8, 9 are broken or foreign objects are caught, the control circuit 10 malfunctions, or the valve body 5a of the exhaust gas recirculation valve 5 is caught by foreign objects. When the valve body 5a of the exhaust recirculation valve 5 is in an open state due to congestion, etc., the abnormality detection device 17
The target movement amount of a and the actual movement amount are compared, and when it is detected that the two do not match even after a set time has elapsed, a signal is output to the actuator 18b of the exhaust gas recirculation stop device 18 and the correction device 12.

Upon receiving the output from the abnormality detection device 17, the exhaust gas recirculation stop device 18 rotates the shutoff valve 18a to close using the actuator 18b, closes the recirculation passage 4, and stops the recirculation of exhaust gas.

On the other hand, the correction device 12 corrects the control signals from the control circuit 10 to the fuel injection device 11 and the ignition device 13 in response to the stoppage of recirculation, for example, leans the air-fuel ratio or retards the ignition timing. It is something. In the above embodiment, the control circuit 10, the correction device 12, and the abnormality detection device 17 are explained as being separate and independent, but they are integrated into a digital computer equipped with each of the above functions, and the entire system is Of course, it may also be provided to perform control.

Moreover, the control of the exhaust gas recirculation valve 5 according to the operating state of the engine is not limited to the exhaust gas recirculation device 6 of the above embodiment, and various electrical or mechanical control devices may be employed. In this case, the means for detecting the open state of the exhaust gas recirculation valve caused by an abnormality in the control device can be changed correspondingly, and the mechanism of the exhaust gas recirculation stop device 18 can also be changed in various ways.

Therefore, according to the control device of the present invention as described above, when an abnormality occurs when the exhaust gas recirculation valve is open and a large amount of exhaust gas is recirculated, this is detected and the recirculation passage is forcibly closed to stop the operation. By correcting the air-fuel ratio or ignition timing according to the stoppage of exhaust gas recirculation, it is possible to perform control that accurately corresponds to the engine operating state, improving fuel efficiency or preventing knocking. It is possible to prevent the occurrence of

[Brief explanation of the drawing]

The drawing is an overall configuration diagram showing an embodiment of the present invention. 1...Intake system, 2...Intake passage, 3.
... Throttle valve, 4 ... Reflux passage, 5 ...
...Exhaust gas recirculation valve, 6...Exhaust gas recirculation device, 7
... Negative pressure passage, 8 ... Negative pressure solenoid valve, 9 ... Atmospheric solenoid valve, 10 ...
・Control circuit, 14...Rotation sensor, 15...
... Negative pressure sensor, 16 ... Valve body position detection sensor, 17 ... Abnormality detection device, 18 ...
・Exhaust gas recirculation stop device.

Claims (1)

[Claims] 1. An exhaust gas recirculation device equipped with an exhaust gas recirculation valve that extracts part of the exhaust gas from the exhaust system and recirculates it to the intake system, and an air-fuel ratio or ignition timing that is set according to the engine operating state and the engine operating state. a control circuit that performs decision control according to the amount of exhaust gas recirculation; an abnormality detection device that detects the open state of the exhaust recirculation valve caused by an abnormality in the exhaust gas recirculation device; An engine comprising: an exhaust gas recirculation stop device that stops recirculation; and a correction device that receives an output from the abnormality detection device and corrects the air-fuel ratio or ignition timing to a value that does not take into account the amount of exhaust gas recirculation. control device.