JPH0629586B2 - Fuel supply control device for internal combustion engine - Google Patents

Description

Description: The present invention relates to a device for controlling the fuel supply of an internal combustion engine.

BACKGROUND ART Asynchronous injection control system during acceleration is well known in which fuel is injected each time the internal combustion engine enters an accelerating operation state. According to this method, the response characteristic during acceleration of the engine can be improved. When performing such asynchronous injection, it is already known to control the fuel injection amount according to the opening speed of the throttle valve. However, if the asynchronous injection amount during acceleration is controlled only according to the opening speed of the throttle valve, the optimum injection amount cannot be given when the load condition of the engine changes. For example, when asynchronous injection during acceleration is performed when the vehicle speed is low and the vehicle speed is low, a large torque shock is caused. On the contrary, when the vehicle speed is low, when the vehicle speed is high, the asynchronous injection at the time of the vehicle speed is high and the asynchronous injection at the time of acceleration causes a lag, etc., and the response characteristic at the time of acceleration is significantly deteriorated.

Therefore, the present invention is to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a fuel supply amount control device capable of improving both drivability and response during acceleration. .

The configuration of the present invention that achieves the above-mentioned object will be described with reference to FIG. 1.
An acceleration detecting means a for detecting whether or not an acceleration operation is required based on a time change amount of the throttle opening; a vehicle speed detecting means d for detecting a traveling speed of a vehicle c on which an internal combustion engine b is mounted;
An asynchronous injection amount determination means e for obtaining an asynchronous injection amount when the detected time change amount of the throttle opening is equal to or greater than a predetermined value, and a fuel supply means f for supplying fuel to the engine b according to the obtained asynchronous injection amount. Therefore, the asynchronous injection amount determining means e sets the asynchronous injection amount to increase as the vehicle speed increases, and when the vehicle speed is less than a predetermined value indicating racing of the engine, the asynchronous injection amount is set to a value other than racing. The feature is that it is set to be larger than the asynchronous injection amount in the vehicle speed range.

The present invention is described in detail below with reference to examples.

FIG. 2 schematically shows an example of an electronically controlled fuel injection type internal combustion engine as an embodiment of the present invention. In the figure, 10 is an engine body, 12 is an intake passage, 14 is a combustion chamber of one cylinder, and 16 is an exhaust passage. The flow rate of the intake air taken in through an air cleaner (not shown) is detected by the air flow sensor 18. The intake air flow rate is controlled by a throttle valve 20 that is linked to an accelerator pedal (not shown). The intake air that has passed through the throttle valve 20 passes through the surge tank 22 and the intake valves 24, and the combustion chamber 1 of each cylinder.
Guided to 4.

The fuel injection valve 26 is actually provided for each cylinder, is controlled to open and close according to an electric drive pulse sent from the control circuit 30 via the line 28, and is sent from a fuel supply system (not shown). Pressurized fuel is intermittently injected into the intake passage 12 (intake port portion) near the intake valve 24.

The exhaust gas after combustion in the combustion chamber 14 is exhaust valve 32.
And the catalytic converter 34 via the exhaust passage 16.
It is discharged into the atmosphere via.

The air flow sensor 18 is provided in the intake passage 12 upstream of the throttle valve 20 and generates a voltage according to the intake air flow rate. This output voltage is fed to the control circuit 30 via the line 36.

The distributor 38 of the engine has a crank angle sensor 4
0 and 42 are attached to these sensors 40,
From 42, pulse signals are output each time the crankshaft rotates 30 ° and 360 °, and these pulse signals are sent to the control circuit 30 via lines 44 and 46, respectively.

A pulse signal is output from the throttle position sensor 48 interlocking with the throttle valve 20 each time the throttle valve 20 rotates by a slight angle, and this pulse signal is sent to the control circuit 30 via the line 50.

The vehicle speed sensor 54 outputs a pulse signal each time the output shaft of the vehicle rotates by a predetermined angle.
It is sent to the control circuit 30 via 6.

FIG. 3 is a block diagram showing a configuration example of the control circuit 30 shown in FIG.

The voltage signal from the air flow sensor 18 is sent to an analog-digital (A / D) converter 70 having an analog multiplexer function, and converted into a binary signal in accordance with an instruction from a microprocessor unit (MPU) 72.

A pulse signal from the crank angle sensor 40 for each 30 ° of crank angle is transmitted via the input / output circuit (I / O circuit) 74 to the MPU.
It is sent to 72 and serves as an interrupt request signal for a crank angle 30 ° processing routine, and also serves as a stepping clock of a timing counter provided in the I / O circuit 74. A pulse signal from the crank angle sensor 42 for each crank angle of 360 ° functions as a reset signal for the timing counter.
The injection start timing signal obtained from this timing counter is sent to the MPU 72 and becomes an interrupt request signal of the injection processing routine for synchronous injection.

The pulse signal from the vehicle speed sensor 54 is sent to the MPU 72 via the I / O circuit 74 and becomes an interrupt request signal of the vehicle speed calculation processing routine.

The pulse signal from the throttle position sensor 48 is also I /
It is sent to the MPU 72 via the O circuit 74 and becomes an interrupt request signal of the processing routine for calculating the throttle opening speed.

In the input / output circuit (I / O circuit) 76, a drive circuit is provided which receives a 1-bit ejection pulse signal having a duration corresponding to the ejection pulse width TAU ′ sent from the MPU 72 and converts this into a drive signal. Has been. A drive signal from this drive circuit is sent to the fuel injection valves 26a to 26d to energize them. As a result, an amount of fuel corresponding to the pulse width TAU is injected.

The A / D converter 70 and the I / O circuits 74 and 76 are connected to an MPU 72, a random access memory (RAM) 78, and a read only memory (ROM) 80, which are main components of the microcomputer, via a bus 82. Has been done,
Data is transferred via this bus 82.

In the ROM 80, a main processing routine program described later, an interrupt processing routine program for each crank angle of 30 °, a vehicle speed calculation interrupt processing routine program, a throttle opening speed calculation interrupt processing routine program, and other programs, and their calculations Data and tables used in the process are stored in advance.

Next, the operation of the above microcomputer will be described with reference to the flowcharts of FIGS.

When the pulse signal for every 30 ° crank angle is sent from the crank angle sensor 40, the MPU 72 executes the interrupt processing routine of FIG. 4 and forms data representing the engine speed NE. First, in step 90, the MPU 7
The contents of the free-run counter provided in 2 are read and the value is set as C ₃₀ . In a next step 91, the current value C ₃₀ and reading ivy value C ₃₀ 'at the previous interrupt
Is calculated from ΔC = C ₃₀ −C ₃₀ ′, and the reciprocal of the difference ΔC is calculated in the next step 92 to obtain the rotational speed NE. I.e. Is calculated. However, A is a constant. The NE thus obtained is stored in a predetermined position of the RAM 78. The next step 93 is to use the content C ₃₀ of the current counter as the previous read value at the time of the next interrupt processing.
The processing of _C30 '← _C30 is performed. Thereafter, after executing other necessary processing, the interrupt processing routine returns to the main routine.

When the pulse signal is sent from the vehicle speed sensor 54, the MPU 72 executes the interrupt processing routine of FIG. 5 to form data representing the vehicle speed VS. Since the processing routine of FIG. 5 is almost the same as that of FIG. 4, its explanation is omitted. However, in the figure, B is a constant.

Further, the MPU 72 has a throttle position sensor 48
When a pulse signal is sent from the CPU, the interrupt processing routine of FIG. 6 is executed to form data representing the throttle opening speed ThS. Since the processing routine of FIG. 6 is almost the same as that of FIG. 4, the description thereof will be omitted. However, in the figure, D is a constant.

When the A / D conversion completion interrupt from the A / D converter 70 occurs, the MPU 72 takes in data representing the intake air flow rate Q of the engine and stores it in the RAM 78 at a predetermined position.

On the other hand, the MPU 72 executes the processing shown in FIG. 7 during the main processing routine. That is, the data representing the throttle opening speed ThS stored in the RAM 78, which is created by the interrupt processing routine of FIG. 6, is compared with the constant value E to determine whether or not the acceleration operation is requested. If ThS ≦ E, the accelerator pedal is depressed at a slow speed and it is determined that acceleration operation is not required, and the main routine is continued. If ThS> E, the accelerator pedal is pressed at a high speed, and acceleration interrupt processing is requested because acceleration operation is requested.

FIG. 8 shows this acceleration interrupt processing routine. As described above, the MPU 72 executes this acceleration interruption process when the throttle opening speed ThS is larger than the constant value E.
First, in step 100, the data representing the vehicle speed VS created in the interrupt processing routine of FIG.
Read more. In the next step 101, this vehicle speed VS
Is less than 2 km / h. VS <2km /
In case of h, step 1 is assumed to be racing.
02, a relatively large constant value F is given as the asynchronous fuel injection pulse width TAU '. This is because there is no load during racing and torque shock does not occur even if a large amount of fuel is injected.

On the other hand, if VS ≧ 2 km / h, proceed to step 103,
An asynchronous injection pulse width TAU 'corresponding to the vehicle speed VS is obtained. A one-dimensional function table for TAU 'for VS is stored in advance in the ROM 80, and the step 1
In 03, the TAU 'for VS is obtained by using the interpolation method or the like. In the next step 104, an injection pulse signal having a duration corresponding to this TAU 'is generated and asynchronous injection of fuel is executed. As a method of creating an injection pulse signal,
For example, in step 104, the injection pulse signal is inverted to "1", the contents of the free-run counter at that time are known, and the value of this counter after TAU 'has elapsed is set in the compare register. When the content of the free-run counter becomes equal to the content of the compare register, an interrupt is generated and the injection pulse signal is inverted to "0".
As a result, an asynchronous injection pulse signal having a pulse width corresponding to TAU 'is formed at each acceleration.

The MPU 72 has a predetermined crank angle, for example 180 ° C.
An injection pulse signal for synchronous injection is formed according to the rotation speed, the intake air flow rate, etc. every A or 360 ° C. A, and the normal fuel injection control is performed by this.

FIG. 9 shows the vehicle speed VS characteristic of the asynchronous injection pulse width TAU 'calculated as described above. Vehicle speed is 2km
If less than / h, it is assumed that racing is being performed and a relatively large amount of fuel is asynchronously injected, while the vehicle speed is 2 km /
When h or more, the amount of fuel is asynchronously injected according to the vehicle speed at that time. In this case, a large amount of fuel is injected asynchronously as compared with the case where the vehicle speed is high and the vehicle speed is low. As a result, when the vehicle speed is high, the rotational speed and torque are increased rapidly during acceleration, and the response characteristics during acceleration are improved. Further, when the vehicle speed is low, the amount of asynchronously injected fuel is small, so that the occurrence of torque shock during acceleration can be prevented.

In the embodiment described above, the asynchronous injection fuel amount during acceleration is controlled to a value that depends only on the vehicle speed.
This may be controlled according to both the vehicle speed and the throttle opening speed.

As explained in detail above, during normal acceleration (when accelerating other than racing), the higher the vehicle speed, the larger the asynchronous injection amount, so the response can be improved and the torque shock can be prevented. Play. In addition, during racing where it is not necessary to consider the torque shock, a large asynchronous injection amount can be obtained in the low vehicle speed range and during acceleration other than racing, so that there is an effect that the engine can be revved up.

[Brief description of drawings]

FIG. 1 is a diagram showing the configuration of the present invention, FIG. 2 is a schematic diagram of an embodiment of the present invention, FIG. 3 is a block diagram showing the control circuit of FIG. 2 in detail, and FIGS. Is a flowchart of a part of the control program of the control circuit shown in FIG. 3, and FIG.
It is a characteristic view of the asynchronous injection fuel quantity in the example of the figure. 18 ... Air flow sensor, 20 ... Throttle valve, 2
6 ... Fuel injection valve, 30 ... Control circuit, 40, 42 ...
Crank angle sensor, 48 ... Throttle position sensor, 54 ... Vehicle speed sensor, 72 ... MPU, 74, 76
... I / O circuit, 78 ... RAM, 80 ... ROM.

Claims (1)

[Claims] 1. An acceleration detection means (a) for detecting whether or not an acceleration operation is required by a time change amount of a throttle opening, and a traveling speed of a vehicle (c) equipped with an internal combustion engine (b). Vehicle speed detection means (d), an asynchronous injection amount determination means (e) for obtaining an asynchronous injection amount when the detected time change amount of the throttle opening is equal to or greater than a predetermined value, and an engine according to the obtained asynchronous injection amount. A fuel supply amount control device for an internal combustion engine, comprising: a fuel supply unit (f) for supplying fuel to (b), wherein the asynchronous injection amount determination unit (e) determines the asynchronous injection amount as the vehicle speed increases. The fuel supply of the internal combustion engine is characterized in that the asynchronous injection amount is set to be larger than the asynchronous injection amount in the low vehicle speed range other than racing when the vehicle speed is less than a predetermined value indicating the racing of the engine. Quantity control device.