JPH025741A - Method for controlling air-fuel ratio of engine with exhaust gas recirculating device - Google Patents

Abstract

PURPOSE:To prevent a temporary over-rich/over-lean condition by correcting an injecting fuel quantity during the operation delay time of an EGR valve according to a correcting quantity based on engine speed and the changed value of an intake-pipe negative pressure. CONSTITUTION:A fuel injection quantity in a steady condition is calculated based on an intake-pipe pressure from an intake pressure sensor 11 and engine speed by an arithmetic and control unit 13. A fuel injection correcting quantity corresponding to the delay in operation of the valve 10 of an EGR 7 is calculated from the changed values of the intake-pipe pressure and engine speed. The fuel quantity injected during the operation delay period of the valve 10 is corrected by this correcting quantity. Hence, because of the changes in the intake-pipe pressure and engine speed due to the rapid accelerating/decelerating operation of an engine 4, even if the delay in operation of the valve 10 takes place or even if the delay is not constant, it will not take place that an air-fuel ratio becomes temporarily over-rich or oven-lean.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides an air-fuel ratio control method for an engine equipped with an exhaust gas recirculation device, particularly when the amount of exhaust gas recirculation changes due to the operation of an exhaust gas recirculation valve. Regarding.

(Conventional technology) Conventionally, an exhaust gas recirculation device (hereinafter also referred to as EGR)
When the throttle valve opens, the EGR boat becomes downstream of the throttle valve, the negative pressure chamber of the diaphragm actuator formed in the EGR valve becomes negative pressure, and the EGR
The throttle valve of the R valve moves together with the diaphragm against the biasing force of the spring to open, and the exhaust gas from the exhaust pipe flows back to the intake pipe.

In this case, if the operating state is steady, this state will be maintained and the amount of exhaust gas recirculated will be steady, and if the throttle valve is closed, the negative pressure chamber of the diaphragm actuator in the EGR valve will be at atmospheric pressure. Then,
The throttle valve of the EGR valve is kept closed by the biasing force of the spring that presses the slam.

(Problem to be Solved by the Invention) However, when the throttle valve changes from an open state to an open state, the pressure in the EGR boat changes from atmospheric pressure to negative pressure, and the throttle valves of the F and G R valves change from leap to open. At this time, negative pressure is introduced to the EGR boat, and there is a time lag before the throttle valve moves together with the diaphragm against the biasing force of the spring and opens, and during this delay time, The amount of recirculation of exhaust gas is small, so the air-fuel ratio becomes overrich during this delay time due to the small amount of recirculation spear, and similarly, when the throttle valve of the EGR valve changes from open to closed, - The drawback was that the air-fuel ratio would sometimes become over-lean, causing temporary disturbances in the air-fuel ratio, resulting in a temporary reduction in engine torque at the peak of rich and lean conditions.

(Object of the Invention) The present invention provides an air-fuel ratio control method for an engine equipped with an exhaust gas recirculation device, in which the air-fuel ratio does not temporarily become over-rich or over-lean even if there is an operation delay in the EGR valve. There is a particular thing.

(Means for Solving the Problems) The present invention supplies fuel to the engine by operating a fuel injection device corresponding to the opening degree of the throttle valve, and also provides an exhaust gas recirculation valve corresponding to the opening degree of the throttle valve. In an engine with an exhaust gas recirculation device that recirculates exhaust gas to the engine by the operation of the fuel injection in a steady state from at least the engine speed and intake pipe negative pressure! [
In addition to calculating t, the fuel injection correction amount corresponding to the 0 delay in the operation of the exhaust gas recirculation valve is calculated from at least the change value of the engine speed and the intake pipe negative pressure, and the operation delay period of the exhaust gas recirculation valve is calculated. The present invention provides an air-fuel ratio control method for an engine equipped with an exhaust gas recirculation VT system, in which the amount of fuel injected into the engine is corrected by the fuel injection correction amount.

(Function) In the engine with the exhaust gas recirculation device configured as described above, the fuel injection amount corresponding to the opening degree of the throttle valve is calculated from the engine speed and intake pipe negative pressure at that time. - On the other hand, the fuel injection correction amount corresponding to the activation delay of the exhaust gas recirculation valve is calculated from the change value of the engine speed and intake pipe negative pressure, and there is no sudden change in the engine speed and intake pipe negative pressure. In steady state, fuel is supplied to the engine without correction.

Next, when the engine speed and intake pipe negative pressure change due to rapid acceleration/deceleration of the engine, a fuel injection correction amount corresponding to the activation delay of the exhaust gas recirculation valve is calculated from this change value, and The fuel injection amount at , that is, the fuel injection amount calculated from the engine speed and intake pipe negative pressure at that time, is corrected by the fuel injection correction amount corresponding to the change value, and the fuel injection amount at this corrected point is is injected into the engine during the delay period of the exhaust gas recirculation valve.

(Effects of the Invention) As a result, the present invention can prevent the air-fuel ratio from temporarily becoming overrich or overlean, even if there is an operation delay in the EGR valve, or even if the operation delay is not constant. This has the effect that the fuel injection amount can always be appropriately controlled in accordance with the reflux layer of exhaust gas.

(Example) Next, the configuration of an example of the present invention will be described with reference to the drawings.

An intake pipe 5 and an exhaust pipe 6 of the engine 4 mix the air from the air filter 2 and the fuel from the electromagnetic fuel injection valve 3 in accordance with the opening degree of the throttle valve 1 and supply a mixture to the engine 4. In between, there is an exhaust gas recirculation system, commonly known as FOR.
7. In this case, the throttle valve 1 on the intake pipe 5 becomes negative pressure when the throttle valve 1 is fully closed but slightly opened.
An EGR 7 is installed that opens and closes a valve 10 by the biasing force of a spring 9 of a diaphragm 8 operated by intake pressure at an upstream position and reciprocating movement against the biasing force.

The electromagnetic fuel injection valve 3 of the engine 4 with the EGR 7 installed in this way is connected to the intake pressure sensor 11 that is attached to the intake pipe 5 and generates an output corresponding to the intake pipe pressure, and the intake pressure sensor 11 that is attached to the engine 4 and is attached to the crankshaft unit. The fuel m corresponding to the operating state of the engine 4 is calculated by inputting each sensor from the engine rotation speed sensor 12, which is also a crank angle sensor that generates a pulse for each angle and generates an output corresponding to the engine rotation speed. Arithmetic control unit 13, in this case,
It is driven and controlled by an output from an arithmetic control unit 13 of a microcomputer, which includes a known ROM 14, RAM 15, CPU 16, an A/D converter 17 including an input/output interface, a waveform shaping circuit 18, a drive circuit 19, and the like.

Next, the operation of this embodiment will be explained according to the flow chart of FIG.

In the operating state of the engine 4, in step 101, the engine rotation speed NE is read at the crank angle corresponding to the intake pipe pressure PM detected by the intake pressure sensor 11 and the engine rotation speed, and in step 102, the engine rotation speed NE and intake pipe pressure PM read in are read. The basic fuel injection amount TP corresponding to is calculated, and step 103t-1 fuel injection OA m'r
It is determined whether the crank angle is such that the actual fuel injection amount TALJ is calculated from P and the correction coefficient, and if the crank angle is not a predetermined crank angle, a predetermined control corresponding to engine control is carried out l171.
After the operation, the above operation is repeated again, and at a predetermined crank angle, the basic fuel injection 1rPBsE in the absence of EGR is calculated using the engine speed NF and intake pipe pressure PM read earlier in step 104. , from the engine speed NE and intake pipe pressure PM already read in step 105, a correction flTPEG corresponding to EGR in a steady state is calculated.
Calculate RB.

Next, in step 106, the previously calculated [1] EGR, that is, TPEGRO, and the currently calculated TPEGRB are 1/
The annealed value of 2 is set as rPEGR, and step 10
Basic fuel injection 1d l-P B S calculated earlier in 7.
[Fuel injection +21 f by reducing the power of the engine
It T P, and in step 108, the PEGR obtained in step 106 is set to T in preparation for the next calculation.
In the state of PEGRO, the actual fuel injection a411TAU is obtained by multiplying the fuel injection II 'r I) previously obtained in step 109 by various correction coefficients, and in a predetermined control operation corresponding to the engine control that follows this model, An amount of fuel corresponding to T A U, that is, fuel corrected according to changes in engine speed and intake pipe negative pressure, is injected into the engine during the activation delay period of the exhaust gas recirculation valve. Ru.

As a result, even if there is a delay in the operation of the EGR valve, or even if the delay is not constant, the air-fuel ratio will not temporarily become over-rich or over-lean, and the amount of fuel injected into the engine will be equal to the exhaust gas. is always appropriately controlled according to the reflux amount.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the mechanical configuration of an embodiment of the present invention;
FIG. 2 is an electrical block circuit diagram of the arithmetic and control unit 13, and FIG. 3 is a flowchart for controlling the arithmetic and control unit 13. 1... Throttle valve 3... Electromagnetic fuel injection valve 4... Engine 5... Intake pipe 6... Exhaust pipe 7... Exhaust gas recirculation device No. 1
Good figure

Claims (1)

[Claims] Exhaust gas recirculation supplies fuel to the engine by operating a fuel injection device that corresponds to the throttle valve opening, and also returns exhaust gas to the engine by operating an exhaust gas recirculation valve that corresponds to the throttle valve opening. In an engine equipped with a device, the amount of fuel injection in a steady state is calculated from at least the engine speed and intake pipe negative pressure, and the operation delay of the exhaust gas recirculation valve is calculated from at least the change value of the engine speed and intake pipe negative pressure. An air-fuel ratio of an engine with an exhaust gas recirculation device, characterized in that a corresponding fuel injection correction amount is calculated, and the amount of fuel injected during an operation delay period of an exhaust gas recirculation valve is corrected by the fuel injection correction amount. Control method.