JPH0475384B2 - - Google Patents

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] Generally, in an electronically controlled fuel injection device, fuel cut control is performed to cut off the fuel supply to the internal combustion engine (hereinafter also referred to as engine) when the engine is decelerated for the purpose of improving fuel efficiency. After the fuel supply is cut, for example, when the accelerator pedal is depressed, the fuel supply is restarted.

Conventionally, as an example of an electronically controlled fuel injection device that performs fuel cut control as described above,
As shown in Publication No. 35320, when it is detected that fuel supply should be restarted, fuel is injected asynchronously with the rotation of the engine crankshaft, and when fuel supply is restarted, the air-fuel ratio temporarily increases to the lean side. A device that solves the problem of misalignment is known.

However, with this type of injection, it is possible to suppress the deviation of the air-fuel ratio toward the lean side by performing asynchronous injection as described above, and after it is detected that fuel supply should be resumed, normal synchronous injection is performed. injection, i.e.
The crankshaft rotates by a predetermined angle (for example, 720
Since a mode is also executed in which fuel is injected every time ℃ A has elapsed, there is a problem in that the air-fuel ratio varies relatively greatly depending on the time point at which the asynchronous injection as described above is performed.

[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 A rotates by a predetermined angle. Calculating means C for calculating, and determining means D for determining whether or not to restart fuel supply after fuel supply to internal combustion engine A is cut off.
The electromagnetic injection valve emits an injection pulse having an injection pulse width corresponding to the injection pulse width calculated above in synchronization with the calculation timing of the calculation means C and at a period N times the calculation period (N is an integer of 2 or more). When the determination means D determines that the fuel supply should be restarted, the output means F outputs the output to the fuel injection device E, and when the determination means D determines that the fuel supply should be resumed, it outputs an injection pulse with an injection pulse width calculated at the calculation timing immediately after this determination, and thereafter , and outputs an 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. 2, in which the injection pulse width is calculated at calculation timing a of 360°C, and the output timing is synchronized with this calculation timing a and has an output cycle of 720°C. In an electronically controlled fuel injection system that outputs injection pulse b at When the LL switch) is reversed from ON to OFF, an injection pulse with the injection pulse width calculated at calculation timing a ₁ immediately after this reversal detection time t ₁ is generated.
P ₁ is output at an output timing b ₁ that is synchronized with the calculation timing a ₁ , and thereafter, an injection pulse P ₂ is generated every 720°C from this output timing b ₁ as a base point.
It outputs P ₃ ....

On the other hand, in the conventional electronically controlled fuel injection system, as shown in Fig. 2, the idle switch is
When it is reversed from ON to OFF, an injection pulse _P4 with a predetermined pulse width is output asynchronously with the crankshaft at the time _t1 when the reversal is detected, and from then on, the output timing C is the same as the output timing that was prohibited due to fuel cut. The injection pulses P ₅ , P ₆ , P ₇ . . . are output again. For this reason, injection pulse P ₅ may be output immediately after injection pulse P 4 is output _{, or injection pulse P 5 may be output nearly 720°C after injection pulse P 4 is output} , resulting in asynchronous injection. The relationship between the output timing of the synchronous injection and the output timing of the synchronous injection causes variations in the air-fuel ratio.

[Example] The present invention will be described below by giving examples and referring to the drawings.

3 and 4 show an embodiment in which the present invention is applied to an internal combustion engine (engine) with simultaneous injection in all cylinders. FIG. 3 is a schematic system diagram of the engine and its surroundings, and FIG. 1 is a block diagram mainly showing the internal structure of a fuel injection control circuit.

In Fig. 3, 2 is a known four-stroke spark ignition engine installed in a car, 4 is an electromagnetic injection valve, 6 is an air cleaner that filters air taken into the engine, 8 is an intake pipe, and 10 is a cylinder. a slot valve for controlling the amount of intake air drawn into the
1 is a spark plug, 12 is an exhaust manifold, 14
is the exhaust pipe. Note that fuel is supplied from a fuel system (not shown) through electromagnetic injection valves 4 provided corresponding to each cylinder, and fuel air is taken in through an air cleaner 6, an intake pipe 8, and a slot valve 10. . After combustion, the exhaust gas is discharged into the atmosphere through the exhaust manifold 12, the exhaust pipe 14, a catalytic converter (not shown), and the like.

16 is a potentiometer-type intake air flow sensor, 18 is a thermistor-type intake air 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, 27 is a throttle opening sensor that detects the opening of the 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 temperature 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 with a frequency proportional to the rotation 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, it may be one that converts changes in magnetic flux into electrical signals using electromagnetic pickup.

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 water temperature sensor 20, and the opening time of the electromagnetic injection valve 4 is thereby controlled. The details will be described later.

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

In the figure, 100 is a microprocessor (CPU) that performs calculations of 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. In the rotation number counter 101, the number of rotations of the crankshaft is counted based on the signal from the aforementioned rotation sensor 22, and when the measurement is completed, 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 sends the interrupt signal via the COMOS bus 150.
The interrupt processing routine is input to the CPU 100 and executed by the CPU 100 for calculating the fuel injection amount.

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 to the CPU 100 from the digital input port 103.

Next, 104 is an analog multiplexer and an A/D
An analog input port consisting of a converter,
The aforementioned intake air amount sensor 16, intake temperature sensor 18,
Each signal from the water temperature sensor 20 and throttle opening sensor 27 is A/D converted, and the signals are sequentially
Loaded into the CPU 100.

As described above, the output information of the rotation number counter 101, the interrupt control unit 102, the digital input port 103, and the analog input port 104 is transmitted to the common bus 15.
0 to the CPU 100.

Furthermore, 105 and 106 are power supply circuits, 107
is RAM, and 108 is ROM. Power supply circuit 10
5. Since it is directly connected to the battery without passing through the key switch 30, power is always applied to the RAM 107, which is supplied with power from the power supply circuit 105, regardless of the key switch 30. On the other hand, the power supply circuit 106 connects the battery 2 through the key switch 30.
8, and from this power supply circuit 106
Power is supplied to items other than the RAM 107. still,
The RAM 107 is a temporary storage unit that is used temporarily during operation, but as mentioned above, power is always applied regardless of the key switch 30.
It is configured so that the stored contents will not be lost even if the engine is turned off and engine operation is stopped, making it a non-volatile memory. The ROM 108 is a read-only memory that stores programs, various constants, and the like.

Further, 109 is a down converter, 110 is a power amplification section, and 111 is a timer. The down counter 109 is a fuel injection time control counter including a register, and the digital signal representing the valve opening time of the electromagnetic injection valve 4 calculated by the CPU 100, that is, the fuel injection amount, corresponds to the actual valve opening time of the electromagnetic injection valve 4. It is converted into a pulse signal with the given pulse width. The power amplifier 110 amplifies the power necessary to drive the electromagnetic injection valve 4. Furthermore, 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, the CPU
The control program processed by 100 will be described as well as the operation of the entire arrangement.

Key switch 30 and starter switch 26
When the engine is started by turning ON, arithmetic processing is started in the main routine 200, and step 20 is started.
Initialization processing is performed at step 1.

Next, in step 202, the analog input port 1
The values corresponding to the cooling water temperature and intake air temperature from 04 are read, and in the following 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 K refers to the map search,
Alternatively, it is a comprehensive correction amount calculated based on the correction amount K ₁ depending on the intake air temperature and the correction amount K ₂ depending on the cooling water temperature, which is obtained by calculation.

Normally, the main routine processing from step 202 to step 203 is executed repeatedly according to the control program, and an interrupt signal (a signal generated every 360°C) for calculating the fuel injection amount 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 number of revolutions N of the crankshaft from the number of revolutions counter 101 is measured,
In the following step 212, the analog input port 10 is
The signal of the intake air amount sensor 16 is taken in from 4 and the intake air amount Q is measured.

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

t=F×Q/N [msec] (F: constant) In the following step 214, the correction amount K obtained in step 203 of the main routine is read out from the RAAM 107, and the fuel injection amount for the engine to operate in the optimum condition is determined. Correction calculation is performed using the following equation.

T=t×K [msec] Here, T is the amount of fuel injected during one rotation of the engine that is optimal for the engine operating condition with respect to the basic injection pulse width t determined in step 213. This is the injection pulse width that takes a value.

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:
For example, whether 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 is not set in the down counter 109 as will be described later, and no injection pulse is output to the electromagnetic injection valve 4 and fuel injection is not performed. do not have.

On the other hand, in step 215, the idle switch is activated to indicate that the conditions for restarting the fuel supply have been met.
When the inversion to OFF is detected, next in step 217, the corrected basic injection pulse obtained in step 214 is doubled to obtain the final injection pulse width.

Next, in step 218, it is determined whether or not the previous execution of interrupt processing was during fuel cut.

If the current interrupt processing is the first one after the determination that fuel supply should be restarted, the determination result of this step 218 is "YES", so the process advances to step 219, and in this step 219, The final injection pulse width determined in step 217 is set in the down counter 109, and the process further proceeds to step 216, where the main routine processing that has been interrupted is restarted.

On the other hand, if the current interrupt process is the second or subsequent one after the determination that fuel supply should be restarted, the determination result in step 218 is "NO", so the process advances to step 220, and this step At 220, it is determined whether or not 720°C has passed. If 720℃ has not yet passed, down counter 1
The process proceeds to step 216 without performing the process of finally setting the injection pulse width to 09, and restarts the main routine process that has been interrupted. Meanwhile 720℃
If A has elapsed, the process advances to step 219, where the final injection pulse width is set in the down counter 109, and then the process advances to step 216, where the main routine processing that has been interrupted is restarted.

Therefore, in the interrupt processing routine,
The basic injection pulse width is calculated every 360°C and correction is made thereto. and,
If the fuel cut condition is satisfied, the process of setting the injection pulse width to the down counter 109 is prohibited, and no fuel injection is 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. 720℃
Fuel injection is performed every time A 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 example, the calculation timing a is set to 360°C.
I explained the case where it is done for each A, but there are also 180 other cases.
It may be done every ℃A or every 90℃A, as long as it 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] As explained above, 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. can.

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

[Brief explanation of the drawing]

Figure 1 is a configuration diagram for clearly demonstrating the present invention, Figure 2
The figure is an explanatory diagram showing an example of the basic operation of the present invention,
FIG. 3 shows an overall configuration of an embodiment of the present invention, FIG. 4 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...Judging means, E...Electrode injection valve, F
...Output means.

Claims (1)

[Scope of Claims] 1. 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; and after the fuel supply to the internal combustion engine is cut off, a determining means for determining whether or not to restart fuel supply; and a determining means for determining whether or not fuel supply should be restarted; An output means for outputting an injection pulse with a corresponding injection pulse width to the electromagnetic injection valve, and when the determination means determines that fuel supply should be resumed, the injection pulse is calculated at a calculation timing immediately after this determination. What is claimed is: 1. An electronically controlled fuel injection device comprising: a device that outputs an injection pulse of a certain width, and thereafter outputs the injection pulse at an output cycle based on this output timing.