JPS60119340A - Electronic control type fuel injection device - Google Patents

Abstract

PURPOSE:To restrain the air-fuel ratio of an engine from shifting toward its lean side upon reinitiation of fuel supply, by delivering injection pulses at the timing of computation just after such a determination that fuel supply should be reinitiated. CONSTITUTION:There are provided a computing means C for computing the width of injection pulse each time when the crankshaft B of an engine A rotates by a predetermined angle, and a determining means D for determining the reinitiation of fuel supply. When the determining means D determins that fuel supply should be reinitiated, a delivery means F delivers injection pulses having an injection pulse width computed at the timing of computation just after the determination of fuel supply reinitiation, and subsequently, delivers injection pulses having an output cycle period based upon this delivery timing, to an electromagnetic injection valve E. With this arrangement the air-fuel ratio of the engine may be restrained from shifting toward its lean side upon reinitiation of fuel injection, and as well dispersion in the air-fuel ratio may be limited to be minimum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an electronically controlled fuel injection device mounted on a vehicle such as an automobile.

[Prior Art] Electronically controlled fuel injection devices are generally used in internal combustion engines (hereinafter also referred to as engines) for the purpose of improving fuel efficiency. ) Fuel cut control is performed to cut the fuel supply to the engine during deceleration. After the fuel supply is cut, the fuel supply is restarted when, for example, the accelerator pedal is depressed.

Conventionally, as an example of an electronic IJl control type fuel injection device that performs fuel cut control as described above,
As shown in the publication, at the same time as it is detected that the fuel supply should be restarted, fuel is injected asynchronously with the rotation of the engine crankshaft, and when the fuel supply is restarted, the air-fuel ratio temporarily deviates significantly to the lean side. There are known methods that solve the problem.

-2- However, with this type of fuel, it is possible to suppress the deviation of the air-fuel ratio toward the lean side by performing asynchronous injection as described above, but after it is detected that the fuel supply should be resumed, the normal Since synchronous injection, that is, a mode in which fuel is injected every time the crankshaft rotates by a predetermined angle (for example, when the crankshaft slightly exceeds 720°C), is performed, the air-fuel ratio changes depending on the point at which the asynchronous injection as described above is performed. There was a problem in that relatively large variations occurred.

[Object of the Invention] In view of the above points, it is an object of the present invention to suppress the air-fuel ratio from shifting toward the lean side when fuel supply is restarted, and at the same time to suppress the variation in the air-fuel ratio depending on the restart point to a sufficiently small level.

[Structure of the Invention] Therefore, as shown in FIG. 1, the electronically controlled fuel injection device of the present invention adjusts the injection pulse width according to the operating state of the internal combustion engine every time the crankshaft B of the internal combustion engine △ rotates by a predetermined angle. -3- Calculating means C for calculating; -3- Judging means for determining whether or not to restart fuel supply after the fuel supply to the internal combustion engine is cut; synchronized with the calculating timing of the calculating means C; and output means F for outputting an injection pulse with an injection pulse width corresponding to the calculated injection pulse width to the electromagnetic injection valve E at a period N times the calculation period (N is an integer of 2 or more), When it is determined by the above determination means that fuel supply should be restarted,
The present invention is characterized in that it outputs an injection pulse having the calculated injection pulse width at the calculation timing immediately after this determination, and thereafter outputs the injection pulse at an output cycle based on this output timing.

An example of the basic operation of the present invention is as shown in FIG.
An electronically controlled fuel injection device that calculates the injection pulse width at a calculation timing a of 0°C△ and outputs an injection pulse b at an output timing that is synchronized with this calculation timing a and has an output cycle of 720°CΔ. When the fuel supply is cut and the injection pulse is not output as shown by the broken line in the figure, the accelerator pedal is depressed and the idle switch (+-, 1-, switch) is turned from ON to OFF. When it is reversed to 1", the injection pulse P1 having the *@ pulse width calculated at the calculation timing a1 immediately after this reversal detection time t1
Output timing b synchronized with the calculation timing a1
1, and from now on, this output timing 1) 1
The pulses P 2 , P are emitted every 720°C from
8... is output.

On the other hand, the conventional electronically controlled fuel injection system, as shown in FIG. is output asynchronously, and from then on, injection pulses P5 and P are generated at the same timing C as the output timing that was prohibited during fuel injection.
b, P+1, . . . are output again.

Therefore, if the injection pulse P5 is output immediately after the injection pulse P4 is output, or if the injection pulse P5 is output 72 seconds after the injection pulse P4 is output.
In some cases, the injection pulse P is output after nearly 0°C A has elapsed, and this causes variations in the air-fuel ratio depending on the relationship between the output timing of asynchronous injection and the output timing of synchronous injection.

[Example] The present invention will be described below with reference to examples and drawings.

3 and 4 show an embodiment in which the present invention is applied to an all-cylinder simultaneous III injection type internal combustion engine. The figure is a block diagram mainly showing the internal configuration of the fuel injection control circuit.

In Fig. 3, 2 is a known 4-samovalve that is installed in a car, 6 is an air cleaner that filters air taken into the engine, 8 is an intake pipe, and 10 is for controlling the amount of intake air taken into the cylinder. 11 is a spark plug, 12 is an exhaust manifold, and 14 is an exhaust pipe. still,
Fuel is supplied from a fuel system (not shown) through electromagnetic injection valves 4 provided corresponding to each cylinder, and combustion air is supplied through an air cleaner 6, an intake pipe 8, and a throttle valve 10. be done. And the exhaust gas after combustion is carried out by the exhaust manifold 12,
It is released into the atmosphere through the exhaust pipe 14, a catalytic converter (not shown), etc.

and 16 is a potentiometer type intake air amount sensor, 18
2 is a thermistor-type intake temperature sensor, 20 is a thermistor-type water temperature sensor, 22 is a rotation sensor, 24 is a fuel injection control circuit, 26 is a starter switch, and 27 is a throttle valve 10
28 is a battery, and 30 is a key switch.

The intake air amount sensor 16 detects the amount of intake air taken into the engine 2 and outputs an analog voltage (analog detection signal @) corresponding to the amount of intake air.

Further, the intake temperature sensor 18 detects the temperature of the air taken into the engine 2 and outputs an analog voltage (analog detection signal) corresponding to the intake temperature. Note that the intake air amount sensor 16 and the intake air temperature sensor 18 are installed in the intake pipe 8.

The water temperature sensor 20 detects the coolant temperature and outputs an analog voltage (analog detection signal) corresponding to the coolant temperature, and the water wetness sensor 20 is installed in the engine 2.

The rotation sensor 22 detects a predetermined rotation angle position of the engine crankshaft and outputs a pulse signal having a frequency proportional to the rotational speed. For example, an ignition coil of an ignition device may be used as the rotation sensor 22, and an ignition pulse signal from a primary terminal of the ignition coil may be used as the rotation speed signal.

Alternatively, an electromagnetic pickup may be used to convert changes in magnetic flux into electrical signals.

Furthermore, the fuel injection control circuit 24 basically calculates the basic fuel injection amount (basic injection pulse width) based on the detection signals of the intake air amount sensor 16 and the rotation sensor 22, and calculates the basic fuel injection amount (basic injection pulse width). The final injection pulse width is determined by correcting the basic fuel injection amount using the signals from the intake air temperature sensor 18 and the water temperature sensor 20, and the opening time of the electromagnetic injection valve 4 is thereby controlled. Details will be described later.

-8- Next, the fuel injection control circuit 24 will be explained based on FIG.

In the figure, 100 is a microprocessor (CPU), which calculates the fuel injection amount (injection pulse width), etc. Further, 101 is a rotation number counter, 102 is an interrupt control unit, and 150 is a common bus. Rotation counter 10
1, the number of rotations of the crankshaft is determined by the signal from the rotation sensor 22 mentioned above, and at the end of the measurement, an interrupt command signal is supplied to the interrupt control section. The interrupt control unit 102 generates an interrupt signal based on the signal, and outputs an interrupt signal to the CPLlloo via the common bus 150.
, and an interrupt processing routine for calculation of the fuel injection amount performed by the CPU 100 is executed.

Further, 103 is a digital input port, and a digital signal from a starter switch 26 for turning on and off a starter (not shown) is inputted from the digital input port 1-103 to the CP (Jloo).

Next, reference numeral 104 is to the analog capo-1 which is composed of an analog multiplexer and an A/D-9 converter, and is connected to the above-mentioned intake air sensor 16, intake air temperature sensor 18, water temperature sensor 20, and throttle opening sensor 27. Each signal of A/
The D-converted signals are sequentially read into the CPU 100.

As described above, the rotation number counter 101, the interrupt control unit 102,
Digital input boat 103 and analog input boat 1
The output information of 071 is sent to CPU1 through common bus 150.
00.

Furthermore, 105 and 106 are power supply circuits, and 107 is a RAM.
, 108 is a ROM. Since the power supply circuit 105 is directly connected to the battery without passing through the key switch 30,
RAMI"07 supplied with power from this power supply circuit 105
Power is always applied to the key switch 30 regardless of the key switch 30. On the other hand, the power supply circuit 106 is connected to the valve 2'8 through the key switch 30.
Power is supplied to everything other than the RAM 107 from. still,
RAM'107 is a temporary storage unit that is used temporarily during operation, but as mentioned above, power is always applied regardless of whether the key switch 30 is turned OFF.
It is configured so that the stored contents will not be lost even if the engine operation is stopped at F, and it forms a non-volatile memory. ROM10
B is a read-only memory that stores programs and various constants.

Further, 109 is a down counter, 110 is a power amplification section, 1
11 is a timer. The down counter 109 is a fuel injection time control counter including a register, and is a counter for controlling fuel injection time.
The digital signal representing the valve opening time of the electromagnetic injection valve 4 calculated by loo, that is, the fuel injection IMI, is the actual electromagnetic injection valve 4.
is converted into a pulse signal with a pulse width that gives the valve opening time. The power amplifier 110 amplifies the power necessary to drive the electromagnetic injection valve 4. Further, the timer 111 constantly measures the elapsed time and transmits it to the CPU 100, where it is used to detect, for example, the number of revolutions N.

Next, based on the flowchart in Figure 5, CPLlloo
The control program processed by the system will be explained, and the operation of the entire configuration will also be explained.

Key switch 30 and starter switch 26-11
- When the engine is started with ONL, main routine 20
Arithmetic processing is started at 0, and initialization processing is performed at step 201.

Next, in step 202, values corresponding to the cooling water temperature and intake air temperature are read from the analog input boat 104, and in the subsequent step 203, a correction amount K is calculated from the values, and the calculation result is stored in the RAM 107. Note that the correction amount is a comprehensive correction amount calculated based on the correction amount 1 corresponding to the intake air temperature and the correction IK2 corresponding to the cooling water temperature, which is obtained by map search or calculation.

Normally, the main routine processing from step 202 to step 203 is repeatedly executed according to the control program, and an interrupt signal for fuel injection @ amount calculation (signal generated every 360°C) from the interrupt control unit 102 is input. Then, even if the microprocessor 100 is processing the main routine, it immediately interrupts the processing and moves to the interrupt handling routine shown at 210.

In step 211, a signal representing the rotation speed N of the -12- crankshaft is measured from the rotation speed counter 101, and in the subsequent step 212, the signal of the intake air amount sensor 16 is fetched from the analog input board 104, and the intake air amount Q is measured. .

Next, in step 213, the basic injection amount (l)l determined from the rotation speed N and the intake air amount Q (that is, the basic injection pulse width t for the electromagnetic injection valve 4) is determined by the following equation.

t = FxQ/N [1 sec] (F: constant) In the following step 214, step 20 of the main routine
The correction amount K determined in step 3 is read out from the RAM 107, and the correction calculation of the fuel injection amount in order to operate the engine in the optimum condition is performed using the following equation.

7-t
l is the injection pulse width that takes the optimum value for the operating condition of the engine.

Next, in step 215, it is determined whether the fuel cut condition is satisfied. This fuel cut condition is well known and will not be described in detail, but for example, it may be that the idle switch is ON and the engine speed is above a predetermined value.

If the fuel cut condition is satisfied in step 215, the process advances to step 216, and the main routine processing that has been interrupted is restarted. Therefore, while the fuel cut condition is satisfied, the final injection pulse width as described later is not set to the down counter 109, and the electromagnetic 1! Fi!
) No injection pulse is output to valve 1 and fuel injection is not performed.

On the other hand, in step 215, if it is detected that the conditions for restarting fuel supply have been met, for example, that the idle switch has been turned OFF, then in step 217, after the correction determined in step 214, the The basic injection pulse is doubled to obtain the final injection pulse width.

Next, in step 218, it is determined whether the previous execution of the interrupt process was during fuel cut.

-14- If the current cutting process is the first one after the judgment that fuel supply should be resumed, the judgment result of this step 218 is rYEsJ, so the process advances to step 219; Then, the final injection pulse width determined in step 217 is counted by the down counter 109.
is set, and the process further proceeds to step 216, where the interrupted main routine processing is resumed.

On the other hand, if the current interrupt processing is the second or subsequent one after the determination that fuel supply should be restarted, the determination result in step 218 is rNOJ, so the process advances to step 220; 720'OAI
! Determine whether or not it has passed.

720''' If before CA elapses, down counter 109
The process proceeds to step 216 without performing the process of setting the final injection pulse width to resume the main routine process that has been interrupted. On the other hand, if 720°C has passed, the process proceeds to step 219, where the final injection pulse width is set in the down counter 109, and the process proceeds to step 216.
Processing suspended = 15 - Resumes main routine processing.

Therefore, in the interrupt handling routine, 360°C
Each time, the basic injection pulse width is calculated and correction is made to it. If the fuel cut condition is satisfied, the process of setting the injection pulse width to the down counter 109 is prohibited, and fuel injection is not performed.

On the other hand, when it is detected that fuel supply should be restarted during fuel cut, the final injection pulse width calculated at the calculation timing at the time of this detection is set in the down counter 109 and fuel injection is restarted. Fuel injection is performed every time 720°C elapses.

For this reason, fuel injection is restarted a very short time after the engine changes to the operating state where fuel supply should be restarted, and after restarting, fuel injection is restarted every time a predetermined crank angle elapses from this restart point. Since this is performed, it is possible to suppress the air-fuel ratio from largely shifting toward the lean side when fuel supply is restarted, and it is possible to sufficiently suppress variations in the air-fuel ratio.

In addition, in this embodiment, the calculation timing a is set to 360-16
- Although we have explained the case where it is done for each CA, there are also 180 other cases.
It may be set every ℃A or every 90℃A, as long as the interval is at least shorter than the interval between injection output timings b and c.

Further, when fuel supply is restarted, the method of shifting the output timing described in the above embodiment and the conventionally known asynchronous injection may be used in combination.

[Effects of the Invention] D. As explained below, according to the present invention, it is possible to suppress the deviation of the air-fuel ratio toward the lean side that occurs when fuel supply is restarted, and at the same time, it is possible to suppress the variation in the air-fuel ratio at the time of restarting to a sufficiently small level. I can do it.

Therefore, it is possible to prevent the engine from misfiring and impairing drivability when fuel supply is restarted, and from deteriorating emissions due to variations in the air-fuel ratio.

[Brief explanation of drawings]

Fig. 1 is a block diagram for clarifying the present invention, Fig. 2 is an explanatory diagram showing an example of the basic operation of the present invention, Fig. 3 is an overall block diagram of an embodiment of the present invention, and Fig. 4 -17- is a block diagram mainly showing the internal structure of the fuel injection control circuit, and FIG. 5 is a flowchart showing the processing. A...Internal combustion engine B...Crankshaft C...Calculating means D...Judgment means E...Electromagnetic injection valve F...Output means agent Patent attorney Tsutomu Sadachi and 1 other person -18-

Claims (1)

[Scope of Claims] Calculating means for calculating an injection pulse width according to the operating state of the internal combustion engine each time the crankshaft of the internal combustion engine rotates by a predetermined angle; a determination means for determining whether or not the supply should be resumed; and a determination means that corresponds to the calculated injection pulse width in synchronization with the calculation timing of the calculation means and at a period that is N times the calculation period (where N is an integer of 2 or more). output means outputs an injection pulse having an injection pulse width to an electromagnetic injection valve, and when the determination means determines that fuel supply should be resumed, the injection pulse width calculated at a calculation timing immediately after this determination is outputted to the electromagnetic injection valve; 1. An electronically controlled fuel injection device comprising: a device that outputs an injection pulse of 1, and thereafter outputs an injection pulse at an output cycle based on this output timing. −1=