JPS6052298B2 - engine control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for controlling 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, since the recirculation of exhaust gas has a negative effect on engine drivability, fuel efficiency, etc., in order to always maintain the optimum amount of recirculation, it is necessary to Various types of exhaust gas recirculation devices, such as electronically controlled exhaust gas recirculation devices, are being adopted, which detect the operating state of the engine by detecting the above, and use a control device to feedback-control the exhaust recirculation valve to the optimum recirculation amount for this operating state. It's getting old.

However, in the above-mentioned exhaust gas recirculation device, the exhaust gas recirculation valve may be closed due to malfunction of the operation system of the exhaust gas recirculation valve, malfunction of the control device, etc., and a predetermined exhaust gas may not be recirculated. The air-fuel ratio or ignition timing of the engine is determined and controlled according to operating conditions such as engine speed and load. Depending on the amount of exhaust gas recirculation, for example, the air-fuel ratio is enriched or the ignition timing is advanced. The air-fuel ratio or ignition timing, which is determined and controlled based on the assumption that a set amount of fuel is 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 this, the present invention provides an exhaust gas recirculation device equipped with an exhaust recirculation valve that extracts part of the exhaust gas from the exhaust system and recirculates it to the intake system. A control circuit that determines and controls the exhaust gas recirculation amount according to the amount of exhaust gas recirculation that is set in accordance with the operating state, a valve position detection device that detects the open/closed position of the exhaust gas recirculation valve, and a control circuit that receives the output of the valve position detection device and detects the An abnormality detection device that detects the closed state of the exhaust gas recirculation valve caused by an abnormality in the exhaust gas recirculation device, and a correction 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 an engine control device equipped with a device;
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. 4 is a recirculation passage for recirculating 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 is an exhaust gas disposed in the recirculation passage 4; This is the exhaust gas recirculation valve of the 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 body 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 to close the valve. The valve body 5a is opened and the amount of recirculation of exhaust gas is controlled 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 solenoid valve 8 and the atmospheric solenoid valve 9 are connected to each other. A negative pressure passage 7 between the idle valve 9 and the negative pressure chamber 5d 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 gas 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. Reference numeral 11 denotes a fuel injection device that injects fuel into the intake passage 2 upstream of the throttle valve 3. The fuel injection device 11 is actuated by a control signal from a control circuit 10 via a correction device 12 to maintain a predetermined air pressure. The fuel ratio is controlled to be the same.

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 speed, 15 is a negative pressure sensor that detects the intake negative pressure downstream of the throttle valve 3, and 16 is a valve attached to the exhaust recirculation valve 5 that detects the moving position of the l valve body 5a. The valve body position detecting sensor is a position detecting device, and detection signals from each of the 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 outputs a control signal to the negative pressure and atmospheric solenoid valves 8 and 9 to control the exhaust recirculation valve 5 so that the target movement amount of the valve body 5a matches the measured movement amount. The system is configured to control the exhaust gas recirculation 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 to perform fuel injection and ignition with this optimum air-fuel ratio and ignition timing. and is configured to control the ignition device 13.

Next, reference numeral 17 denotes an abnormality detection device for detecting the closed state of the exhaust gas recirculation valve 5 caused by an abnormality in the exhaust gas recirculation device 6. Movement amount signal and valve body position detection sensor 16
A signal indicating the actual measured movement amount of the valve body 5a is input.

This abnormality detection device 17 compares both the above signals and detects the valve body 5a.
There is a device that detects and issues an output signal when the measured amount of movement does not match the target amount of movement even after a set time has elapsed and the device remains closed. 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 abnormally closed state of the exhaust gas recirculation valve 5, that is, the stoppage of recirculation of exhaust gas, the correction device 12 starts the fuel injection. correcting the control signals from the control circuit 10 to the device 11 and the ignition device 13;
The air-fuel ratio and ignition timing are set to values that do not take into account the optimal exhaust gas recirculation amount (lean 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 15.
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 of the memory device by combining with the negative pressure signal from the The actual movement amount from the 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 by the opening/closing time 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 so that the valve body 5a is moved from the recirculation passage 4. The system recirculates a predetermined amount of exhaust gas depending on the current operating state to suppress the generation of NOx. Further, the control circuit 10 calculates the engine operating state based on the engine speed and intake negative pressure, and the optimal air-fuel ratio and ignition timing when the above-mentioned optimal exhaust gas recirculation amount is recirculated, and generates a control signal according to the calculation. is output to the fuel injection device 11 and the ignition device 13, and fuel injection and ignition are performed 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 malfunctioning or foreign objects are caught, the control circuit 10 malfunctions, the valve body 5a of the exhaust gas recirculation valve 5 is stuck, etc. When the valve body 5a of the exhaust gas recirculation valve 5 is in the closed state, the abnormality detection device 17 compares the target movement amount and the measured movement amount of the valve body 5a, and detects that the two do not match even after the set time has elapsed. At times, a signal is output to the correction device 12.

The correction device 12 that receives the output of the abnormality detection device 17 controls the control circuit 10 for the fuel injection device 11 and the ignition device 13.
The control signal from the engine is corrected in response to the stoppage of recirculation, for example, to make the air-fuel ratio leaner or to retard the ignition timing.

In the above embodiment, the control circuit 10 and the correction device 1
2 and the abnormality detection device 17 are described as being separate and independent, but it goes without saying that they may be integrated into a digital computer equipped with each of the above functions and provided to control the entire system. be.

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 can be adopted. In this case, the means for detecting the closed state of the exhaust gas recirculation valve caused by an abnormality in the control device can also be changed accordingly.

Therefore, as described above, according to the control device of the present invention, when the exhaust gas recirculation valve is closed and exhaust gas is not recirculated abnormally, this is detected and the exhaust gas recirculation is stopped in response to the exhaust gas recirculation being stopped. By correcting the fuel ratio or ignition timing, control can be performed that accurately corresponds to the operating state of the engine, and it is possible to improve fuel efficiency or prevent the occurrence of knocking.

[Brief explanation of drawings]

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, 11 ... Abnormality detection 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, a valve position detection device that detects the opening/closing position of the exhaust gas recirculation valve, and a valve position detection device that receives the output of the valve position detection device and detects the occurrence of abnormalities in the exhaust gas recirculation device. The device comprises an abnormality detection device that detects the closed state of the exhaust gas recirculation valve, 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. Characteristic engine control device.