JPS60187732A - Control device for fuel injection of engine - Google Patents

Abstract

PURPOSE:To improve the operability in re-acceleration while restricting non-synchronous injection so that an air-fuel ratio may not be overrich, by a method wherein the non- synchronous injection can be conducted again when some period passes even after the non-synchronous injection is conducted in prescribed times. CONSTITUTION:At a step 160, the necessity of non-synchronous injection is determined. If the determination is affirmative, it is determined at a step 120 whether or not a count value of a counter C2 is less than prescribed three times determined beforehand. When said value is less than three, non-synchronous injection is conducted at a step 170. This non-synchronous injection is conducted by delivering a signal of a prescribed pulse width to a fuel injection valve through an I/O circuit in the same way as synchronous injection irrespective of a crank angle, and in this case, injection is executed simultaneously with respect to all cylinders. When the non-synchronous injection is conducted three times in this way, the count value of C2 becomes three, and the non- synchronous injection is conducted no longer. When the synchronous injection is conducted four times after C1 is cleared at a step 131, however, the determination at the step 120 turns to be affirmative, and thus re-opening of the non-synchronous injection is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection control device for a fuel injection type engine.

[Prior art]

In conventional fuel injection engines, the operating state of the engine is detected, and the optimal amount of fuel is injected synchronously at a predetermined crank angle to supply fuel to the combustion chamber. When a predetermined operating state of the engine is detected, fuel is supplied to the combustion chamber by asynchronous injection at the time of detection, regardless of the crank angle.

The predetermined operating states of the engine in which asynchronous injection is performed include acceleration, startup, and return from fuel cut, and by performing not only synchronous injection but also such asynchronous injection, it is possible to quickly respond to changes in operating conditions. can. However, if asynchronous injection is performed without limit, the air-fuel ratio will become overrich and the exhaust gas purification performance will deteriorate.

Therefore, conventionally, when asynchronous injection is performed a predetermined number of times,
Asynchronous injection should not be performed unless deceleration operation is performed thereafter (Japanese Patent Application Laid-Open No. 58-81290).

However, if asynchronous injection is restricted in this way, if the engine accelerates once and then accelerates again without decelerating, asynchronous injection will not be performed during re-acceleration, resulting in poor acceleration driveability. There is a fear.

[Purpose of the invention]

In view of such conventional problems, an object of the present invention is to perform asynchronous injection again after a certain period of time even if asynchronous injection is performed a predetermined number of times, thereby preventing the air-fuel ratio from overshooting. The objective is to improve drivability during re-acceleration while limiting asynchronous injection to prevent it from becoming rich.

[Structure of the invention]

The structure of the present invention for achieving this object will be explained with reference to FIG.

In the fuel injection control device for an engine as described above, the counting means counts the number of times asynchronous injection has been performed, and when the counted number of times reaches a predetermined number, the inhibiting means prohibits the asynchronous injection.

Further, the period measuring means measures the period after the asynchronous injection is performed, and when the period measured by the period measuring means reaches a predetermined period, the clearing means clears the number of times counted by the counting means.

Therefore, if asynchronous injection is performed a predetermined number of times, it will be regulated by the prohibition means, but if a predetermined period of time elapses thereafter,
The restriction is lifted by clearing means.

[Results of invention]

According to the present invention, asynchronous injection is regulated to such an extent that the air-fuel ratio does not become overrich, but upon re-acceleration after a predetermined period of time has elapsed, asynchronous injection is performed again, thereby improving acceleration drivability.

〔Example〕

Hereinafter, embodiments of the present invention will be explained from one side.

FIG. 2 shows an electronically controlled fuel injection engine as an example. In the figure, 10 represents an engine body, 12 represents an intake passage, 14 represents a combustion chamber, and 16 represents an exhaust passage. The flow rate of intake air taken in through an air cleaner (not shown) is controlled by a throttle valve 18 that is also linked to an accelerator pedal (not shown). The intake air that has passed through the throttle valve 18 is guided into the combustion chamber 14 via a surge tank 20 and an intake valve 22. On the way, between the air cleaner and the throttle valve 18,
An air flow meter 24 is provided to detect the amount of intake air. Air flow meter 24 detects the amount of intake air as a voltage value, and this voltage signal is sent to control circuit 28 via line 26. Further, a throttle position sensor 58 is connected to the throttle valve 18, and the throttle position sensor 58 generates a detection signal by detecting an idle opening or an opening of a predetermined value or more. , the detection signal is sent to the control circuit 28 via line 56.

The fuel injection valve 30 is actually provided for each cylinder, and is controlled to open and close in response to electrical drive pulses sent from the control circuit 28 via a line 32, and is injected from a fuel supply system (not shown). The pressurized fuel is intermittently injected into the intake passage 12 near the intake valve 22.

The exhaust gas after being burned in the combustion chamber 14 passes through the exhaust valve 34 and the exhaust passage 16 and then to the catalytic converter 36.
emitted into the atmosphere via

From the crank angle sensors 40 and 42 provided in the distributor 38, the crankshaft (not shown) is detected at 30°,
A pulse signal is output each time it rotates 360°,
Pulse signals for every 30 degrees of crank angle are sent to the control circuit 28 via a line 44 and a pulse signal line 4G for every 360 degrees of crank angle, respectively.

An intake temperature sensor 48 is provided within the air flow meter 24 to detect the temperature of the intake air, and its output voltage representative of the detected intake air temperature is fed to the control circuit 28 via line 50. A water temperature sensor 52 for detecting the coolant temperature is also provided in the cylinder block of the engine, and its output voltage representing the detected coolant temperature is sent to the control circuit 28 via a line 54.

FIG. 3 shows an example of the configuration of the control circuit 28 shown in FIG. 2. In FIG. In the figure, the air flow meter 24, intake temperature sensor 48, water temperature sensor 52, crank angle sensors 40 and 42, throttle position sensor 58, and fuel injection valve 30 provided for each cylinder are each represented by blocks. .

The output voltages of the air flow meter 24, intake temperature sensor 48, and water temperature sensor 52 are sent to an A/D converter 60. The A/D converter 60 has an analog multiplexer function, and selects the signal from each sensor according to the instruction signal from the microprocessor (MPU) 62.
Convert to obtain 2 communication signals.

Pulse signals every 30 degrees of crank angle from the crank angle sensor 40 are sent to the MP via an input/output circuit (110 circuit) 64.
The signal is sent to U62 and used to calculate the engine speed, and also serves as an increment clock for a timing counter provided in I10 circuit 64. In addition, the pulse signal for each 360° crank angle from the crank angle sensor 42 is
It serves as the above-mentioned timing counter cent signal.

The timing signal obtained from this timing counter is sent to the MPU 62 and becomes an interrupt request signal for the fuel injection processing routine.

The detection signal of the throttle position sensor 58 is I10
The signal is sent to the circuit 64 and taken in according to instructions from the MPU 62.

In the input/output circuit (110 circuit) 66, a well-known fuel injection control circuit including a register etc. is provided, and the MPU 6
From the binary data regarding the injection pulse width sent from 2, an injection pulse signal having the pulse width is formed. This injection pulse signal is sent to the fuel injection valve 30 via a drive circuit (not shown) to activate it. As a result, an amount of fuel corresponding to the pulse width of the injection pulse signal is injected.

The A/D converter 60 and the ■/○70 circuit 646 are connected to the main components of the microcomputer, such as an MPIJ 62, a random access memory (RAM) 68, and a read-only memory (ROM) 70 via a lotus 72. , data is transferred via this lotus 72.

The ROMTO contains a main processing routine program, an interrupt processing routine program for every 30' crank angle, and other programs, as well as an evening program for these calculation processes.
Various necessary data, tables, etc. are stored in advance.

According to a predetermined program stored in the ROM 70, M
The PLJ 62 sends a message to the A/D converter 60 to instruct the start of A/D conversion at predetermined time intervals, and the data representing the intake air amount, intake air temperature, and cooling water temperature are transmitted to the A/D converter 60. 6
The data is taken into the computer by an A/D conversion completion interrupt from zero and stored in the RAM 68 as is.

Further, engine rotation speed data determined based on pulse signals generated from the crank angle sensor 40 at every 30° crank angle is also stored in the RAM 68.

A timing signal from a timing counter in I10 circuit 64 is generated every 180 degrees of crank angle in the case of a four-cylinder engine, and when this timing signal is generated subroutine 8 of FIG. 4 is executed. First, in step 150, synchronous injection is performed. This synchronous injection
This is done by a well-known method, and RAM6
Determine the basic fuel injection pulse width from the intake air amount and engine speed stored in RAM 68, and further determine the basic fuel injection pulse width from data such as intake air temperature or cooling water temperature stored in RAM 68. llt and increase the fuel injection pulse width. The thus determined data regarding the fuel injection pulse width is transmitted to the fuel injection valve 30 in the I10 circuit 66.
is converted into a signal for driving the fuel injection valve 30 and supplied to the fuel injection valve 30. Note that the fuel injection in this case is independent injection that is performed independently for each cylinder.

In the next step 132, a counter C1 that counts the number of times synchronous injection is performed is incremented, and in step 14
1, it is determined whether the count value of the counter C1 has reached a predetermined number of times 4 (a predetermined period) or more. Then, when the count value of the counter C1 reaches a predetermined number of times 4 or more,
In step 142, a counter C2, which will be described later, is cleared.

On the other hand, subroutine B in FIG. 5 is a time interrupt routine executed every 12 milliseconds, and in step 160, the necessity of asynchronous injection is determined. This is performed according to a well-known procedure, and an affirmative determination in step 160 is made, for example, when the following predetermined operating state is detected.

(2) When a signal is generated from the crank angle sensor 40 after the first signal is generated from the crank angle sensor '9-42 when the engine is started.

(2) When the opening degree of the throttle valve 18 detected by the throttle position sensor 58 is no longer the idle opening degree from the fuel cut state during deceleration operation.

■When the rate of increase in the amount of intake air is greater than a predetermined value.

If an affirmative determination is made in step 160, it is determined in step 120 whether the count value of a counter c2, which will be described later, is less than a predetermined number of times 3.

If the count value of counter C2 is less than 3, step 170
At , asynchronous injection is performed. This asynchronous injection is performed according to a well-known procedure, and a signal with a constant pulse width is sent to I10 in the same way as in the case of synchronous injection, regardless of the crank angle.
The fuel is output to the fuel injection valve 30 via the circuit 66, and in this case, all cylinders are injected at the same time.

In the next step I'10, a counter c2 that counts the number of times asynchronous injection has been performed is incremented. Further, in step 131, the aforementioned counter C1 is cleared. Note that the counting operation is performed using the values of the counters C8 and C2 and a free run counter in the MPU 62.

Synchronous injection and asynchronous injection are performed in this way, but when asynchronous injection is performed three times, step 110 is processed three times and the counter c2 becomes 3, so after that step 1
This step 160 requires asynchronous injection at step 60.
Even if it is determined that step 120 is negative,
If step 170 is not processed, asynchronous injection will no longer occur.

However, if synchronous injection is performed four times after the counter C1 is cleared in step 131, then step 13
2 is processed four times and the count value of the counter C□ becomes 4, so step 141 is affirmed and step 14 is executed.
At 2, counter C2 is cleared. Therefore, an affirmative decision is made in step 120, and asynchronous injection becomes possible again.

Fig. 6 illustrates the above-mentioned operation, and shows the states of synchronous injection, request for asynchronous injection, prohibition of asynchronous injection, and asynchronous injection in order from the top. Injection is performed, but when asynchronous injection is performed three times, asynchronous injection is prohibited and the air-fuel ratio is prevented from becoming overrich. However, after the asynchronous injection is performed and the synchronous injection is performed four times, the prohibition of the asynchronous injection is lifted, and if there is a request for the asynchronous injection, the asynchronous injection is performed in response to the request. Therefore, asynchronous injection is performed even during re-acceleration, improving drivability during re-acceleration.

In addition, in the flowcharts of FIGS. 4 and 5,
The process of step 110 corresponds to the counting means of the present invention,
The process of step 120 corresponds to the prohibition means of the present invention,
The processing of steps 131 and 132 corresponds to the period measuring means of the present invention, and the processing of steps 141 and 142 corresponds to the clearing means of the present invention.

Although specific embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and includes various embodiments within the scope of the claims. For example, the period measured by the period measuring means may be a period during which a predetermined number of signals from the crank angle sensor 40 or 42 are generated, or may be a predetermined time. Further, the predetermined number of times "4" in step 141 in FIG. 4, which corresponds to the predetermined period in the clearing means, is preferably set to "6" for an independent injection 6-cylinder engine, and for a simultaneous injection type or group injection type engine. In this case, it is desirable to set it to "2" or "3".

[Brief explanation of the drawing]

FIG. 1 is a claim correspondence diagram, FIG. 2 is a schematic diagram of an embodiment of the present invention, FIG. 3 is a block diagram of the control circuit of FIG. 2, and FIGS. 4 and 5 are microcomputer The control f
FIG. 6, a flowchart of the ll program 11, is a time chart explaining the operation of one embodiment. 1o-----Engine main body 28----Control circuit 30-----Fuel injection valve 40.42----Crank angle sensor 58----
- Throat position sensor Fig. 1 Fig. 6

Claims (1)

[Claims] 1. Detects the operating state of the engine and synchronously injects the requested amount of fuel at a predetermined crank angle to supply fuel to the combustion chamber of the engine. A fuel injection control device for an engine that detects a predetermined operating state and, when the predetermined operating state is detected, asynchronously injects fuel at the time of detection and supplies fuel to a combustion chamber regardless of the crank angle. a counting means for counting the number of times the counting has been performed, and when the number of times counted by the counting means reaches a predetermined number,
A prohibiting means for prohibiting asynchronous injection, a period B1 measuring means for measuring a period after the asynchronous injection is performed, and a period B1 measuring means for measuring a period after the asynchronous injection is performed, and when the period measured by the 1ul1 measuring means reaches a predetermined period, the number of counts of the counting means is cleared. A fuel injection control device for an engine, comprising: a clearing means;