JPS60156948A - Electronically-controlled fuel injector - Google Patents

Abstract

PURPOSE:To reduce a shock, by providing a means for changing the speed of the return from OTP control to normal control, depending on the condition of an engine, to prevent its torque from being sharply altered. CONSTITUTION:An electronically-controlled fuel injector is put under normal control in which a theoretical air-fuel ratio is used as an aimed value, or under OTP control which is performed to set the ratio of fuel to air at a larger value than the theoretical value. In a step S1, it is judged whether or not an OTP control condition is in the range of the execution of the OTP control. When said condition has sharply and greatly gone out of the range, a step 5 is taken to make an OTP increment value FOTP zero to stop the OTP control and perform based on a basic fuel injection quantity. When the OTP control condition has slowly gone out of said range little by little, the OTP increment value FOTP is diminished (steps S7, S8) to gradually shift the fuel injector from the OTP control to the normal control. The torque of an engine is thus prevented from being sharply altered, to reduce a shock.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to an electronically controlled fuel injection system for an internal combustion engine, and more particularly to improvement of control when returning from a rich air-fuel mixture combustion state to a normal combustion state.

Background of the Invention In a conventional electronically controlled fuel injection system, under certain conditions, the signal from the 02 sensor determines whether the air-fuel ratio is richer or leaner than the stoichiometric air-fuel ratio. In this case, so-called feedback control is performed to increase the amount so that the actual air-fuel ratio matches around the stoichiometric air-fuel ratio. In addition, in order to prevent abnormal overheating of the catalytic converter, for example, when the following conditions are met, the feedbank control is stopped and the so-called OTP (OverT
It is known to perform empire protection (abnormal overheating prevention) control.

1. Engine speed: 500 or more rpm 2. Throttle opening: 50 or more Combustion was immediately stopped with a rich mixture and controlled to maintain the normal stoichiometric air-fuel ratio, but this had the problem of causing shock to the engine.

OBJECTS OF THE INVENTION The present invention has been made to solve these problems, and it is an object of the present invention to reduce the shock that occurs when transitioning from O'VP control to normal control.

Structure of the Invention As mentioned above, the reason why a shock occurs when returning from OTP control to normal control is thought to be due to the following reasons. That is, during OTP control, the engine torque is relatively large because combustion is performed with a rich mixture, but when normal control is restored, combustion is performed with a leaner mixture and the torque decreases. This is because in conventional devices that immediately return from OTP control to normal control, a sudden change in torque occurs during the transition. Therefore, in the present invention, in order to avoid this, the return speed from OTP control to normal control is determined according to the engine condition. In an electronically controlled fuel injection device that performs control and OTP control that controls the air-fuel ratio to a value smaller (richer) than the stoichiometric air-fuel ratio, means for detecting whether OTP control execution conditions suddenly deviate significantly; If the conditions suddenly and significantly deviate, OTP control will immediately return to normal control.
OT when the OTP control execution conditions gradually deviate slightly.
The electronically controlled fuel injection device includes means for gradually returning from P control to normal control.

Embodiment of the Invention FIG. 1 is a block diagram of essential parts showing an example of the hardware configuration of an electronically controlled fuel injection system of the present invention.

In the figure, 10 is a control section of an electronically controlled fuel injection system, and an input interface circuit 13 is connected to a microcomputer 11 via a bus 12. A ROM 14 stores programs, etc. RAM 15 for temporary storage; A/D converter 16 for converting analog signals into digital signals; consisting of an output ink face circuit I7 and a constant voltage power supply 18; The output signal of the crank angle sensor that detects the reference position, rotation angle, and cylinder position, the output signal of the throttle opening sensor 20 that detects idle and high load conditions, and the output of the 02 sensor 21 that detects the oxygen concentration in the exhaust pipe. signal.

An output signal from the starter 22 that detects when the engine is starting.

The output signals of the vehicle speed sensor + edict that detect the current vehicle speed are applied to the A/D converter 16, and the output voltage of the battery 24, the output signal of the intake temperature sensor 5 that detects the intake air temperature, and
The output signals of intake pipe negative pressure sensors that detect intake pipe negative pressure are respectively added.

Further, the output of the output ink face circuit 17 is connected to an injector 27.

The so-called feed bank control, which is normal control, is performed by input ink face circuit 13. By reading the output signals of various sensors from the A/D converter 16, performing a known predetermined calculation, and driving the injector 27 via the output ink face circuit 17 for the timing and period obtained from the result. , the actual air-fuel ratio is controlled to be approximately the stoichiometric air-fuel ratio. Since such normal control is well known, detailed explanation will be omitted. In the present invention, apart from such normal control, OTP control condition determination and control are performed at predetermined time intervals.

FIG. 2 is a flowchart showing an example of OTP control processing, and 81 to S8 indicate each step.

As shown in the figure, in step S1, the microcomputer 11 determines whether or not the above-mentioned OTP control execution conditions are satisfied. This reads the output signal of the crank angle sensor and the throttle opening sensor 20 provided in the distributor 19 via the input ink face circuit 13, and also reads the intake pipe negative pressure via the A/D converter 16. This is done by reading the output signals of the sensor 26 and comparing the respective values with determination conditions set in advance in the ROM 14 or the like.

As a result of the above determination, if the OTP control execution conditions are satisfied, R
For example, set the value of the OTP increase value storage area of A M 15 to 0.
It is initialized to a certain value within the range of about 0.09 to 0.20, for example 0.2 (S2). Then, the process moves to step S3.

Step S3 is a step for calculating the fuel injection time TAXI by the injector 27, and is a step for calculating the fuel injection time TAXI by the injector 27.
LI can be determined by multiplying the basic fuel injection time TP by (1,000 FOTP). Therefore, during 0'FP control, the fuel injection time TAU becomes longer than in the normal case where the value of the OTP increase value POTP is zero, and combustion is performed with a rich air-fuel mixture.

Further, as a result of the above determination, if it is determined that the OTP control execution condition is not satisfied, the RAM 15 is written in 1. It is determined whether or not the O'r p increase value FOTPO value that has been set a is zero (S4). If it is zero, OTP control was not executed last time, so the OTP increase value FOTP value of RAM +5 is set to zero. (35), the process moves to step S3 and normal control is executed. However, if it is determined in step S4 that the OTP increase value 1'OTP is not zero, the OTP
The process moves to step S6 in which it is determined whether or not the control condition has suddenly become thicker (or not).
It is determined whether or not the rate of change of the value of 6 is greater than a certain reference value by, for example, comparing the difference with the previous value with the reference value. If it is small, it will gradually come off and there is no request to reduce the deceleration. Therefore, when the driver releases the accelerator pedal to apply engine braking, the throttle opening sensor 20
A change in the opening of the engine or a change in the negative pressure in the intake pipe becomes large and is treated as a request for deceleration reduction. However, if the throttle opening is gradually reduced, it is treated as not a request for deceleration reduction. Ru. If the OTP control conditions suddenly deviate greatly, the process moves to step S5, the OTP increase value FOTP is set to zero, and the process moves to step S3. Therefore, OTP control is immediately stopped and control is performed using the basic fuel injection amount. On the other hand, if the OTP control conditions are gradually deviated from the OTP control conditions, the OTP increase value FOTP is increased at a certain rate, for example, 2% of the initial value, at each attenuation timing.
The value of is subtracted (S7, S8), and the process moves to step S3. Here, the attenuation timing refers to timing at fixed intervals determined by an internal timer of the microcombinator 11, or timing at every fixed number of injections. Follow °C
1OT l) If the control execution conditions gradually deviate slightly, the depth of the OTP control (the size of the 0'rP in quantity value) gradually becomes shallower, and the OTP control gradually shifts to normal combustion control. That will happen.

FIG. 3 is a diagram showing an example of a change in the air-fuel ratio when the present invention is applied. This shows a case where it is slightly off. If the o ”r p control execution conditions suddenly deviate greatly, the air-fuel ratio will immediately return to its normal state, but if the OTP control execution conditions gradually deviate slightly, the air-fuel ratio will also gradually increase, i.e. Gradually transition to unrich state.

-In addition, in the above embodiment, the o'r p increase value FO
The rate at which the TP is reduced may be changed depending on the conditions for return. For example, the difference ΔHE between the previous engine rotation speed and the current engine rotation speed is set to a different reference value ΔHE.
NEI, 8NE2. Compared with ΔNE3, ΔHE≦ΔN
When E1, reduce FOTP by 5% ΔNEI <Δ11
When B≦8NE2, the difference in weight loss ΔPH is determined by 10% at different reference values ΔPMI, ΔPM2. It may be compared with ΔPM3 and similarly reduced.

As described in detail, according to the present invention, when the OTP control execution condition gradually deviates slightly, the OTP control is gradually returned to the normal control.

Sudden changes in steering speed can be prevented, and shocks can be reduced or eliminated, making it possible to improve riding comfort.

In addition, when the OTP control execution conditions suddenly deviate greatly, it is generally when the driver intends to decelerate.
Immediately return control to normal control.

This is done to ensure that sufficient deceleration is achieved.

[Brief explanation of drawings]

Fig. 1 is a Boocock diagram of the main parts showing an example of the hardware configuration of the electronically controlled fuel injection device of the present invention, and Fig. 2 is an OT P
Flowchart 1-1 showing an example of control processing FIG. 3 is a diagram showing an example of a change in the air-fuel ratio when the present invention is applied. 10 is a control section of an electronically controlled fuel injection device, 11 is a microcomputer, 13 is an input ink face circuit, 14 is a ROM, and 15 is an l? A M, 16 is a to/D converter, I7 is an output ink face circuit, 19 is a distributor incorporating a crank angle sensor, 20 is a throttle opening sensor, and 26 is an intake pipe negative pressure sensor. Patent applicant Fujitsu Ten Ltd. Representative Patent attorney Tamamushi Go 1 person outside the department Figure 2 Figure 3

Claims (1)

[Claims] In an electronically controlled fuel injection system that performs normal control that controls the air-fuel ratio using the stoichiometric air-fuel ratio as a target value and OTP control that controls the air-fuel ratio to a value richer than the stoichiometric air-fuel ratio,
Means for detecting whether or not p-control execution conditions suddenly and significantly deviate; and means for immediately returning from OTP control to normal control when OTP control execution conditions suddenly and greatly deviate, and OTP control execution conditions gradually deviating slightly. 1. An electronically controlled fuel injection device comprising means for gradually returning from O'rP control to normal control when the O'rP control occurs.