JP2501851B2 - Engine fuel control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an engine fuel control device that detects the intake air amount of an engine using a Karman vortex and controls the fuel supply amount of the engine based on this detection output. It is about.

[Conventional technology]

In fuel control in this type of device, an inter-process intake air amount is measured and calculated using a vortex flowmeter that outputs a signal of a frequency proportional to the intake air amount of the engine, and the measured calculation value is multiplied by a correction coefficient and the power supply Is calculated based on the voltage of the battery, the time for driving the injector is calculated, and the injector is drive-controlled according to the calculation result to control the fuel supply amount to the engine.

FIG. 4 is a block diagram showing a vortex flowmeter applied to a fuel control system for an engine according to the present invention, which will be described with reference to FIG. 4 in order to explain a conventional technique.

First, in FIG. 4, a flow meter 1 having a vortex generator 2 is provided.
The ultrasonic wave transmitter 4 and the ultrasonic wave receiver 5 are arranged so as to face each other, and the ultrasonic wave is propagated across the flow of the Karman vortex train 3 generated on the downstream side of the vortex generator 2. The ultrasonic oscillator 4 is excited by the acoustic wave oscillation circuit 6.

Ultrasonic waves that cross the Karman vortex street flow are Karman vortex street 3
Is phase-modulated by and is received by the ultrasonic receiver 5. The received signal is shaped by the waveform shaping circuit 8 and then output to the phase comparator 9.

On the other hand, the output of the ultrasonic oscillation circuit 6 that excites the ultrasonic transmitter 4 is applied to the voltage control phase shift circuit 7.

The voltage control phase shift circuit 7 maintains the high frequency stability of the ultrasonic oscillation frequency signal as it is and controls only the phase shift angle. This voltage control phase shift circuit 7
Phase shifts the output of the ultrasonic oscillation circuit 6 with the phase comparator 9
Add to

The phase comparator 9, the ultrasonic oscillation circuit 6, the voltage control phase shift circuit 7 and the loop filter 10 form a phase locked loop. Note that 11 is a low-pass filter.

The phase comparator 9 performs phase comparison between the output of the waveform shaping circuit 8 and the output of the voltage control phase shift circuit 7, adds the comparison result to the loop filter 10, and adds the unnecessary frequency component of this comparison result to the loop filter 10 To remove.

The voltage control phase shift circuit 7 controls the phase shift angle of the output signal of the ultrasonic oscillator circuit 6 according to the output voltage of the loop filter 10 and outputs it to the phase comparator 9.

The output of the phase comparator 9 is input to the loop filter 10 and also to the first frequency variable filter 12 via the low pass filter 11.

The first frequency variable filter 12 is a high-pass filter, and passes a high-frequency component of the output signal of the low-pass filter 11 and sends it to the second frequency variable filter 13.

The second frequency variable filter 13 is a low-pass filter and passes low-frequency components and outputs it to the waveform shaping circuit 14.

In the first and second frequency variable filters 12 and 13,
As shown in FIG. 5, the first variable frequency filter 12, which serves as a high-pass filter, removes noise components at frequencies below the lower limit pass frequency f _L , and the second variable frequency filter 13 serves as a low-pass filter. Means that noise components due to the engine having a frequency above the upper limit pass frequency f _U will be removed. Therefore, the lower pass frequency
The pass band between the first and second frequency variable filters 12 and 13 is between f _L and the upper limit pass frequency f _U.

This engine noise is a comparatively low frequency noise caused by the pulsation of the air flow, a low output frequency caused by the so-called wind noise generated when the air passes through the air valve, that is, when the flow rate is low. High frequency noise or high output frequency noise generated when the supercharger is operating.

Since the generation area of these noises fluctuates and the air flow rate also fluctuates due to the instantaneous behavior of the engine, the bandwidth of the vortex frequency is considerably wide, and therefore the first and second frequency variable filters 12 and 13 are used. Are combined.

The vortex frequency signal that has passed through the first and second frequency variable filters 12 and 13 is waveform-shaped and amplified by the waveform-shaping amplifier circuit 14, and the vortex frequency signal is output.

At the same time, the eddy frequency signal is frequency-voltage (hereinafter, f
The voltage is converted into a voltage corresponding to the frequency by a conversion circuit 15 (referred to as -V), and the pass bands of the first and second frequency variable filters 12 and 13 are controlled by this voltage.

As a result, the pass bands of the first and second frequency variable filters are changed, and the width of the pass bands shown by hatching in FIG. 5 is changed.

[Problems to be Solved by the Invention]

This vortex flowmeter has a problem in that when measuring the intake air amount of an engine having a supercharger, the fuel control cannot be performed accurately because the vortex signal wave is disturbed by the ultrasonic noise generated by the supercharger. The noise that increases as the rotation speed increases increases the intake air amount, so that the disturbance is removed after passing through the first and second frequency variable filters 12 and 13.

However, when the throttle valve is suddenly closed, the intake air amount is reduced, but the rotation of the supercharger does not suddenly decrease due to inertia or the like.
The second variable frequency filter 13 for the signal at the input end of 12
The signal at the output end of has a waveform with an extremely poor S / N.

In this waveform, noise is erroneously determined as a signal, and an extremely high frequency is output after passing through the second frequency variable filter 13. Therefore, in the deceleration region when the throttle valve is closed, the fuel supply amount to the engine is excessively calculated and supplied, and there is a problem that overrich during deceleration causes deterioration of drivability. .

The present invention has been made to solve such a problem, and accurately detects the intake air amount of the engine to accurately measure the fuel supply amount of the engine without erroneously measuring noise generated when the throttle valve is closed. An object of the present invention is to obtain an engine fuel control device that can be well controlled and has excellent controllability for the engine.

[Means for solving the problem]

An engine fuel control apparatus according to the present invention includes an eddy flow meter having a frequency variable filter means, and controls a fuel supply amount to the engine based on the output, and an opening of a throttle valve is a predetermined value or less. When it is detected, the pass band fixing means for fixing the pass frequency band of the frequency variable filter means to the minimum frequency within the variable frequency band range of the filter means is provided.

[Action]

In the engine fuel control device according to the present invention, the upper limit frequency of the pass frequency band is fixed to the minimum frequency within the variable frequency band range of the filter means by the pass band fixing means, and high frequency noise when the throttle valve is closed is eliminated. By removing it, the S / N ratio of the vortex flowmeter is improved and the fuel control is made highly accurate.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of the entire apparatus according to an embodiment of the present invention. In FIG. 1, 20 is a well-known engine mounted on a vehicle, 21 is a pulse according to the rotation of the engine 20 (for example, from the rise of the pulse). 180 crank angle until the next start
Crank angle sensor that outputs (°), 22 is the engine
20 intake manifold, 23 exhaust manifold of engine 20, 24 a surge tank provided upstream of intake manifold 22 for reducing intake air flow, 25 a throttle provided in intake passage upstream of surge tank 24 The valve 26 is linked to the opening and closing of the throttle valve 25,
A throttle opening sensor that outputs an analog signal corresponding to the opening, 27 is a vortex that is installed in the intake passage further upstream from the throttle valve 25 and outputs a signal of a frequency according to the amount of air taken into the engine 20. An air flow sensor (hereinafter referred to as AFS) as a flow meter, 28 is an air cleaner installed at the inlet of the intake passage.

30 is a crank angle sensor 21 and a throttle opening sensor 26
And an output signal of the AFS27 as an input to control the AFS27 and also control, for example, four injectors 29 provided for each cylinder of the engine 20. This controller
30 is composed of the following components. Reference numeral 31 is a microcomputer (hereinafter referred to as a microcomputer) having a ROM 31A storing the flow shown in FIGS. 2 and 3 as a program, a RAM 31B as a work memory and a CPU 31C, and 32 is an output terminal of the AFS27. And the input terminal P _{1 of the} microcomputer 31
The interface connected between measures the cycle of the AFS27 output signal. 33 is an A / D converter connected between the throttle opening sensor 26 and the input terminal P _{2 of the} microcomputer 31, 34 is a waveform shaping circuit, the output of the crank angle sensor 21 is input, and the output is the ratio of the microcomputer 31. Input terminal P ₃ and counter 35
It is configured to be inputted to. 36 is a timer connected to the interrupt input terminal P ₅ of the microcomputer 31, and 37 is an A / D converter for A / D converting the voltage of the battery (not shown) and outputting it to the input terminal P ₆ of the microcomputer 31. 38 is microcomputer 31 and driver 3
The output terminal of the driver 39 is connected to each injector 29 by a timer provided between the driver 39 and the timer.

FIG. 4 shows the detailed structure of the AFS 27 in FIG. 1, and the description of the parts described in the “Prior Art” column in the same drawing is omitted to avoid duplication. Reference numeral 1 in FIG.
A gate circuit 16 is newly added in addition to the portions indicated by 15 to 15, and the output voltage of the fV conversion circuit 15 is supplied to the second frequency variable filter 13 via the first frequency variable filter 12 and the gate circuit 16. Is also configured to join
The passband fixed signal output from the microcomputer 31 shown in FIG. 1 is input to the gate circuit 16. When the microcomputer 31 detects that the valve opening of the throttle valve 25 detected by the throttle opening sensor 26 in FIG. 1 is below a predetermined opening, the gate circuit 16 controls the pass band fixing control from the microcomputer 31. A signal is applied to fix the upper limit frequency of the pass band of the second frequency variable filter 13 to the minimum frequency within the variable frequency band range of the filter means.

Next, the operation will be described. Engine 20 uses combustion air for air cleaner 28, AFS27, throttle valve 25, surge tank
24, Intake through the intake manifold 22. The injector 29 is opened by the output of the control device 30 to supply fuel to each cylinder of the engine 20. The exhaust gas after combustion is released to the atmosphere through the exhaust manifold 23.

On the other hand, the output of the AFS 27 has its cycle measured by the interface 32 and is input to the microcomputer 31. The output of the throttle opening sensor 26 that detects the opening of the throttle valve 25 is
It is A / D converted by the A / D converter 33 and input to the microcomputer 31. The microcomputer 31 determines whether the throttle opening of the throttle valve 25 is less than or equal to a predetermined value based on the throttle opening data, and outputs a control signal from the output terminal P ₇ according to the result of this determination to output the signal of the AFS 27. Control the pass band. The output of the crank angle sensor 21 is sent to the microcomputer via the waveform shaping circuit 34.
Input to the interrupt input terminal P _{3 of} 31 and the counter 35. The microcomputer 31 performs an interrupt process for each rising edge of the output of the crank angle sensor 21, and detects the cycle between the rising edges of the output of the crank angle sensor 21 from the output of the counter 35. The timer 36 generates an interrupt signal at the interrupt input terminal P ₅ of the microcomputer 31 every predetermined time. The A / D converter 37 converts the battery voltage V _{B (} not shown) into an A / D
After conversion, the microcomputer 31 takes in the data of the battery voltage every predetermined time. Timer 38 is preset by the microcomputer 31, it outputs a pulse of the pulse value calculated is triggered from the output terminal P ₈ of the microcomputer 31, this output driver
Drive the injector 29 via 39.

Further, the operation of the microcomputer 31 will be described with reference to FIGS. 2 and 3.

FIG. 2 shows the main program of the microcomputer 31. First, when a reset signal is input to the microcomputer 31, in step 201, the RAM 31B, input / output port, etc. in the microcomputer 31 are initialized, and in step 202, the battery voltage V _B is A / D converted to V _B in the RAM 31B. Store as. Next, at step 203, the data table f ₁ recorded and set in the ROM 31A in advance is mapped from the battery voltage data VB, the dead time T _D is calculated and stored in the RAM 31B. Next, at step 204, for example, a cooling water temperature sensor (not shown) detects the cooling water temperature of the engine 20, and a correction coefficient K _C for correcting the fuel amount is calculated according to the detection result, etc., and the result is stored in the RAM 31B. To store. Then step 205
At A, the throttle opening signal from the throttle opening sensor 26 is A / D converted by the A / D converter 33, and the throttle opening data V _θ is read from the input terminal P ₂ . Next step
At 206, the throttle opening data V _θ is compared with a comparison value α corresponding to a predetermined opening of the throttle valve 25,
If the throttle opening data V _θ exceeds the comparison value α, the opening of the throttle valve 25 exceeds the predetermined opening, and therefore, the process returns to step 202 and the throttle opening data V _θ is compared with the comparison value α.
If the following is true, the opening degree of the throttle valve 25 is equal to or smaller than the predetermined opening degree, so that the passband fixing control signal is output to the AFS 27 in step 207. After the processing of step 207, the process returns to step 202. The main routine is executed by repeating the above operation.

FIG. 3 shows a microcomputer based on the output of the crank angle sensor 21.
The interrupt input terminal P ₃ of the 31 shows the interrupt process when the interrupt signal is generated. In step 301, the AFS27 output signal is cycle-measured by the interface 32, and the counter and
Based on the measurement data of the rotation cycle of the engine 20 measured by 35, calculation data (load data) AN of the intake air amount between processes, which is the intake air amount per cycle of the engine 20, is calculated. Next, at step 302, the correction coefficient K _C and the dead time T _D are read from the RAM 31B and the injector drive time is read.
Calculate T ₁ according to the calculation formula of K _C × AN + T _D. Next, in step 303, the calculation result T ₁ is set in the timer 38, and after setting, the timer 38 is triggered in step 304 to set the driver 3
The injector 29 is driven via 9. After the processing of step 304, the process returns to the main routine. Next, the operation of the AFS 27 when the passband fixed control signal is output from the microcomputer 31 will be described with reference to FIG. The operation up to the control of the pass band widths of the first and second variable frequency filters 12 and 13 has already been described. Here, the AFS27
Only the characteristic part of the above will be described.

Since the conventional problem occurrence area is only the rapid deceleration area, the opening degree of the throttle valve 25 is detected by the throttle opening degree data 26, and the microcomputer 31 indicates that the valve opening degree of the throttle valve 25 is less than the predetermined value. When detected, the gate circuit 15 outputs f-
The output voltage of the V conversion circuit 15 is clipped and the second frequency variable filter 13 is fixed to the region L as shown in FIG.

As a result, the high frequency component is forcibly removed, and the signal wave on which the high frequency noise is superimposed becomes the first frequency variable filter.
Even when input to 12, the low-frequency signal from which noise has been removed is extracted at the output end of the second frequency variable filter 13.

The gate circuit 16 may control the pass band of the second frequency variable filter by bypassing in response to the throttle opening.

〔The invention's effect〕

As described above, the present invention fixes the upper limit frequency of the pass band of the second frequency variable filter to the minimum frequency within the variable frequency band range of the filter means when the valve opening of the throttle valve is equal to or less than the predetermined opening. Since the fuel control is performed in this way, there is an effect that it is possible to obtain highly accurate fuel control without erroneously measuring the noise generated when the throttle valve is closed as the vortex frequency.

[Brief description of drawings]

FIG. 1 is a block diagram of the entire apparatus showing one embodiment of the present invention,
2 and 3 are flow charts showing the operation flow of the microcomputer in FIG. 1, FIG. 4 is a detailed block diagram of the AFS in FIG. 1, and FIG. 5 is an output frequency and variable filter in the present invention. It is explanatory drawing which shows the relationship with a passage frequency. In the figure, 1 ... Flowmeter, 2 ... Vortex generator, 3 ... Karman vortex train, 4 ... Ultrasonic transmitter, 5 ... Ultrasonic receiver, 6 ...
... Ultrasonic oscillator circuit, 7 ... Voltage control phase shift circuit, 8 ...
... Waveform shaping circuit, 9 ... Phase comparator, 10 ... Loop filter, 11 ... Low-pass filter, 12 ... First frequency variable filter, 13 ... Second frequency variable filter, 14 ...
Waveform shaping circuit, 15 ... fV conversion circuit, 16 ... Gate circuit, 20 ... Engine, 21 ... Crank angle sensor, 25 ...
Throttle valve, 26 ...... Throttle opening sensor, 27 ... AF
S, 29 ... Injector, 30 ... Control device, 31 ... Microcomputer, 32 ... Interface, 33 ... A / D converter, 34
...... Waveform shaping circuit, 35 …… Counter, 36 …… Timer, 37
...... A / D converter, 38 …… Timer, 39 …… Driver. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A detection means for detecting a vortex signal generated in response to an amount of air taken in by an engine, and an output signal of the detection means of the frequency variable filter means for removing noise superimposed on the vortex signal. A fuel control device for an engine, comprising: an eddy flow meter having a frequency variable filter means for passing in a variable frequency band according to a frequency of an output, and controlling a fuel supply amount to the engine based on an output of the vortex flow meter, When it is detected that the opening degree of the throttle valve provided in the intake passage of the engine is equal to or less than a predetermined value, the upper limit frequency of the pass frequency band of the frequency variable filter means is set to the minimum value within the variable frequency band range of the filter means. A fuel control device for an engine, comprising a pass band fixing means for fixing the frequency.