JPS60249651A - Electronic control type fuel injector - Google Patents

Abstract

PURPOSE:To reduce the distribution of air-fuel ratio by determining the correction coefficient of the limit value compared with the fundamental fuel injection pulse width according to the acceleration and deceleration state, when the fuel injection pulse width is limited according to the value due to the processing of the fundamental fuel injection pulse width. CONSTITUTION:When an engine 1 is in operation, the fundamental fuel injection amount (injection time width) W is calculated in a control circuit 20 on the basis of the outputs of an air amount sensor 8 and a revolution speed sensor 11. Then, the weighted average procesing value T is obtained on the basis of the fundamental injection amount W, and the both values W and T are compared. When W>T or W<T, the relation of W>T' or W<T' (T' is a prescribed limit value) is judged, and when the judgement is YES, the above-described limit value is outputted as the fundamental injection amount Wi. Then, the fundamental injection amount Wi is corrected accoring to the correction amount K determined according to the output of a water-temperature sensor 10, and fuel injection valves 51-56 are controlled according to the corrected fuel injection amount.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an electronically controlled fuel injection device for an internal combustion engine.

[Prior art]

Conventionally, in electronically controlled fuel injection devices for internal combustion engines,
Set a constant maximum injection pulse width limit during acceleration,
Additionally, a constant minimum injection pulse width reduction is set during deceleration.

FIG. 1 shows how the air-fuel ratio changes during acceleration and deceleration in this case. During acceleration, the amount of air measured by the airflow meter increases relative to the instantaneous amount of engine intake air (actual amount of air taken into the combustion chamber), and the air-fuel ratio becomes lynch. Also, during deceleration, the amount of air measured by the airflow meter is smaller than the amount of instantaneous engine intake air, and the air-fuel ratio becomes lean. Such over-richness during acceleration or over-lean during deceleration results in poor drivability and increased emissions.

In view of this, conventionally, fixed maximum injection pulse width limitation and fixed minimum injection pulse width limitation schemes are used to cope with the phenomenon during full acceleration and deceleration. However, according to the research of the present inventor, over-rich and over-lean phenomena occur not only during full acceleration/deceleration but also during intermediate acceleration/deceleration during rising and falling, and even during intermediate acceleration/deceleration, the same phenomenon as during full acceleration/deceleration occurs. There are problems in that drivability deteriorates and emissions increase, and countermeasures must be taken to address these problems.

In view of the above-mentioned problems, the electromagnetic injection valve of the internal combustion engine is provided with a means for regulating the fuel injection pulse signal by the time width of the fuel injection pulse signal applied to the electromagnetic injection valve of the internal combustion engine. The basic fuel injection pulse width W (W=F An electronically controlled fuel injection device has been proposed in Japanese Unexamined Patent Publication No. 58-25531.

According to this method, the basic injection pulse width W and the pulse width W
Compare the restricted limit value T'(T'=TxC),
For example, when W<T' during deceleration, it is set as WT', and by reducing the disturbance in W, the disturbance in the air-fuel ratio is reduced.

However, according to this proposal, the limit value T'(T
Since the correction value (C) of '=TXC) is kept constant, there is a problem in that it is difficult to adjust the air-fuel ratio during acceleration/deceleration to λ#1 for various acceleration/deceleration states. In other words, the correction value (C) is determined in a sudden deceleration state, and the air-fuel ratio is
(In this case, since the degree of lean is large,
In a slow deceleration state (increasing the limit value), the problem arises that the air-fuel ratio lynches.

[Purpose of the invention]

In view of the above problems, the present invention aims to solve the above problems by determining the correction value (C) according to the acceleration/deceleration state.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 shows an electronically controlled fuel injection device as an embodiment of the present invention. In FIG. 3, an engine 1 is a four-stroke spark ignition engine installed in an automobile, and intakes combustion air through an air cleaner 2, an intake pipe 3, and a slot valve 4. The output of the control circuit 20 opens the electromagnetic fuel injection valves 51 to 56 to supply fuel to each cylinder. The exhaust gas after combustion is released into the atmosphere through the exhaust manifold 6, exhaust pipe 7, etc. The intake pipe 3 includes a potentiometer-type intake air amount sensor 8 that detects the amount of intake air taken into the engine 1 and outputs an analog voltage according to the amount of intake air.
is installed. Also installed is a thermistor-type intake temperature sensor 9 that detects the temperature of intake air and outputs an analog voltage according to the intake air temperature. Further, the engine 1 is equipped with a thermistor-type water temperature sensor 1o that detects the coolant temperature and outputs an analog voltage (analog detection signal) according to the coolant temperature. Detects the rotation speed of the shaft and outputs a pulse signal with a frequency corresponding to the rotation speed. As this rotational speed sensor 11, for example, an ignition coil of an ignition device may be used.
The ignition pulse signal from the primary terminal of the ignition coil may be used as the rotational speed signal. The throttle valve is also provided with an idle switch 12 that detects that the throttle opening is below a set value. The control circuit 2o is a circuit that calculates the fuel injection amount based on the detection signals of the sensors 8 to 12, and adjusts the fuel injection amount by controlling the opening time of the electromagnetic fuel injection valves 51 to 56.

The control circuit 20 will be explained with reference to FIG.

200 is a micro 10 setter (C) that calculates the fuel injection amount.
PU). Reference numeral 201 is a rotation number counter that counts the engine rotation number based on a signal from the rotation speed (number) sensor 11.

Further, this rotation number counter 201 sends an interrupt command signal to the interrupt control unit 202 in synchronization with the engine rotation.
Upon receiving this signal, the interrupt control unit 202 outputs an interrupt signal to the CPU 200 via the common bus 212. The digital input port 203 transmits digital signals such as a starter signal from the starter switch 13 that turns on and off the operation of a starter (not shown) to the CPU 200.

The analog input port 204 is composed of a synchronized multiplexer and an AD converter, and has the function of converting each signal from the intake air amount sensor 8 and the cooling water temperature sensor 9 from analog to digital, and sequentially reading the signals into the CPU 200. Each of these units 201, 20
The output information of nodes 2, 203, and 204 is transmitted to the CPU 200 through the common path 212. A power supply circuit 205 is connected to the battery 14 through the key switch 15. 206 is a random access memory (RAM) that can be read and written. 207 is a read-only memory (
ROM). 20B is a fuel injection time control counter including a register, which is composed of a down-counter, and is controlled by the CPU 20.
A digital signal representing the opening time of the electromagnetic fuel injection valves 51 to 56, that is, the fuel injection amount calculated at 0, is converted into a pulse signal with a pulse time width giving the actual opening time of the electromagnetic fuel injection valves 52 to 56. do. Reference numeral 209 represents a power amplification unit that drives the electromagnetic fuel injection valves 52 to 56. 210 measures the elapsed time with a timer and transmits it to the CPU 200. The rotational speed counter 201 measures the engine rotational speed once per engine rotation based on the output of the rotational speed sensor 11, and supplies an interrupt command signal to the interrupt control section 202 at the end of the measurement. The interrupt control unit 202 generates an interrupt signal in response to the signal, and causes the CPU 200 to calculate the fuel injection amount and execute an interrupt processing routine.

FIG. 5(a) shows a schematic flowchart of the CPU 200, and the functions of the CPU 200 will be explained based on this flowchart, as well as the operation of the entire configuration. When the key switch 15 and starter switch 13 are turned on to start the engine 1, the main routine arithmetic processing is started at the start of step SO, initialization processing is executed at step S1, and analog A digital value corresponding to the cooling water temperature is read from the input port 204. In step S3, a fuel correction value K is calculated from the result and the result is stored in the RAM 206. When step S3 ends, the process returns to step S2. Usually CP
The U200 repeatedly executes the main routine processing from 82 to S3 in FIG. 5(a) according to the control program.

When the interrupt signal from the interrupt control unit 202 is input, the CPU 200 immediately interrupts the main routine processing even if it is in progress, and moves to the interrupt processing routine in step S40 shown in FIG. 5(b). . Step S
41 is the engine rotation speed N from the rotation speed counter 201.
Then, in step S42, a signal representing the intake air amount Q is taken in from the analog input port 204. Next, in step S43, the engine rotation speed N1
The basic fuel injection amount determined from the intake air amount Q and the constant F (that is, the injection time width W of the electromagnetic fuel injection valves 52 to 56)
). The calculation formula is W=, (FX (Q/N))
It is. Next, in step S44, a weighted average process, which will be described later, is performed to correct the basic injection amount W. Next, in step S45, the correction amount K for fuel injection determined in the main routine is read out from RAM2O6, and correction calculation of the injection amount (injection time width) that determines the air-fuel ratio is performed. data is set in the counter 208. Next, the process advances to step S47 and returns to the main routine. When returning to the main routine, the process returns to the processing step at which it was interrupted due to interrupt processing.

The general functions of the microprocessor 200 are as described above.

Next, the method of correcting the basic injection amount W in step 344 in FIG. 5(b) is illustrated in FIG. Step 5441
In this step, weighted average processing of the basic injection amount W is performed. The calculation formula is Tn-((J1)Tn-++Wn)/J. Here, J is a constant, 2,22°24,...
...2m is convenient, T is the weighted average processing value,
W is the basic injection amount, n is 0.1゜2,...
It is n. The larger J increases the smoothing effect,
If it is made smaller, the smoothing effect will be smaller. Then step 54
At 42, the basic injection amount W and the weighted average processing value T are compared.

Proceed to step 5443 when WET Proceed to step 5446 when W<T Proceed to step 5449 when W=T Next, the calculation formula for the limit value T' (minimum value and maximum value) in steps 443 and 446 is T' = T X C+
.

(C2). Here, the values of 01 and C2 are variables determined from ΔW in FIG. In step 5443, the weighted average processed value T is multiplied by the count CI (C+≧1) to obtain T' and T is corrected. Next, in step 5444, the basic injection amount W is compared with the corrected weighted average processed value T', and if it is WET', the process proceeds to step 5445 and the fuel injection pulse width Wi is set to T'. If W≦T', the process advances to step 5449 and Wi is set to W.

When W<T in step 5442, step 5446
Proceed to step 1, multiply T by C2 (C2≦1), obtain T', and correct T. Next, in step 5447, W and T' are compared, and if W<T', the process advances to step 3448 and W
i'4cT'. If W≧]゛′, Wi is set to W in step 5449. Step S44
ends the explanation. In this way, the basic weighted average processing of the injection pulse width W is performed, and the injection pulse width is limited according to the weighted average value according to the acceleration/deceleration state. In the embodiment of the present invention, ΔW was used as a parameter for the correction term (C) of the control value T';
A rate of change in intake pipe pressure or the like can be used as a parameter.

〔Effect of the invention〕

As explained above, according to the present invention, disturbances in the basic injection amount during acceleration/deceleration are limited by the weighted average processing value T', and furthermore, the limit value is determined according to the acceleration/deceleration state of the engine. This makes it possible to reduce disturbances in the air-fuel ratio during acceleration and deceleration, and prevent deterioration of emissions, drivability, etc.

[Brief explanation of the drawing]

Figure 1 is a waveform diagram that explains disturbances in the air-fuel ratio during acceleration and deceleration, Figure 2 is a waveform diagram that explains the target air-fuel ratio and target injection pulse width during acceleration and deceleration, and Figure 3 is a waveform diagram that explains the disturbance in the air-fuel ratio during acceleration and deceleration. FIG. 4 is a block diagram of the control circuit in the device shown in FIG. 3; FIG. 5 a and b are shown in FIG. 4; FIG. 6 is a flowchart of the microprocessor, FIG. 6 is a flowchart of the basic injection amount correction process in an embodiment of the present invention, and FIG. 7 is a characteristic diagram showing the relationship between injection amount change rate ΔW and correction coefficient CI (C2). DESCRIPTION OF SYMBOLS 1...Engine, 2...Air cleaner, 3...-Intake pipe, 4...Throttle valve, 51, 52, 53,
54゜55.56...Fuel injection valve, 6...Exhaust manifold, 7...Exhaust pipe, 8...Air amount sensor, 9
... Intake temperature sensor, 11 ... Rotation speed sensor, 12
... Idle switch, 20 ... Control circuit, 200
...Microprocessor. Representative Patent Attorney Takashi Okabe Figure 1 Figure 5 (b) Figure 6

Claims (1)

[Claims] 1. Means for regulating the amount of fuel according to the operating state of the internal combustion engine according to the time width of the fuel injection pulse signal applied to the electromagnetic injection valve of the internal combustion engine, Basic fuel injection pulse width w determined from quantity Q and constant F
(W=Fx (Q/N)), and is equipped with an electronically controlled fuel injection device in which a limit on the fuel injection pulse width is set according to the value of the cough annealing process. , the limit value T'(
An electronically controlled fuel injection device characterized in that a correction coefficient C of T'=TXC) is determined according to an acceleration/deceleration state. 2. The electronically controlled fuel injection device according to claim 1, wherein the cough soothing process is performed by weighted average calculation. 3. The electronically controlled fuel injection device according to claim 1 or 2, wherein the injection pulse width is limited only during acceleration or deceleration as a transient state of internal combustion engine operation. .