JPS5857618B2 - Intake flow rate detector for fuel injectors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake flow rate detector used in a fuel injection type internal combustion engine, and more particularly to an intake flow rate detector having a dam plate for measuring intake flow rate disposed in an intake pipe of an internal combustion engine. Regarding.

BACKGROUND ART Recently, a device has been developed as an intake flow rate detector necessary for a fuel injection type internal combustion engine, which detects the intake flow rate by arranging a dam plate in an intake pipe and detecting the intake air flow rate based on the angular position of the dam plate.

Japanese Patent Laid-Open No. 47-9354 discloses such an intake flow rate detection device.

FIG. 1 schematically shows the intake system of a conventional fuel injection type internal combustion engine, in which a throttle valve 2 is disposed in an intake pipe 1, a movable contact 3 that responds to the throttle valve, and a fully closed position contact 4.
and the fully open position contact 5 constitute a throttle valve switch 6.

The movable contact 3 is adjusted to be in contact with the contact 4 when the throttle valve 2 is in the fully closed position, and to be in contact with the contact 5 when the throttle valve 2 is in the fully open position.

A dam plate 7 for measuring intake flow rate is provided upstream of the throttle valve 2 .

The dam plate 7 is rotated by the intake air flow in the direction of arrow A.

Therefore, the angular position of the dam plate 7 varies depending on the air flow rate, and this variation is converted into an electrical quantity by a potentiometer 9 having a slider 8 responsive to the dam plate 7.

Reference numeral 10 denotes a switch for starting the fuel pump drive motor, which includes a movable contact 11 that responds to the dam plate T and a fixed contact 12 that comes into contact with the movable contact 11 when the dam plate 7 is rotated by a certain angle or more.

In the conventional example described above, the fuel pump drive motor start switch 10 must operate at a very small intake air flow rate, which is actually quite difficult to adjust.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a dam plate-type intake flow rate detector that also has a function of generating a fuel supply pump start signal and eliminates the need for a fuel pump drive motor start switch.

An embodiment of the present invention is shown in FIG.

Reference numeral 1 denotes an intake conduit of an internal combustion engine using an electronic fuel injection system, and a dam plate 7 for measuring an intake air flow rate is disposed in this conduit.

The dam plate 7 is equipped with a potentiometer 9 as in the case of Fig. 1.
The slider 8 is engaged, and the slider 8 slides on the resistor R1 in response to the dam plate 7.

A voltage is supplied to both ends of the resistor R1 via the resistor R2,
A voltage is generated in the slider 8 according to the angular position of the dam plate 7.

In this example, the above voltage is supplied from the injection valve drive pulse generation circuit 13.

The dam plate 7 and the potentiometer 9 constitute an intake flow rate detector, and the potential difference between the connecting point J1 between the resistors R1 and R2 and the slider 8 is supplied as an output to the injection drive circuit 13. .

The injection valve drive pulse generation circuit 13 supplies an injection valve drive pulse with an appropriate pulse width and timing to the injection valve drive circuit 14 in accordance with various parameters such as an ignition pulse signal, a water temperature signal, an ambient temperature signal, and a start signal.

The injection valve drive circuit 14 operates an injection valve (not shown) in response to an injection valve drive pulse.

The injector drive pulse generating circuit 13 further requires throttle valve fully open and throttle valve fully closed signals, and the intake flow sensor according to the invention supplies these signals via lines 15, 16.

On the other hand, the fuel supply pump starting signal is supplied from the injection valve drive pulse generation circuit 13 to the drive circuit 19 that drives the fuel pump motor 18 via the line 17.

The intake flow detector according to the invention provides a pump start signal to the drive circuit 19.

The intake flow rate detector according to the present invention generates the pump start signal described above by comparing the potential of the slider 8 with a reference potential.

Both ends of a series circuit consisting of resistors R31R4t and R5tR6 are connected to both ends of resistor R1 to generate a reference potential.

The comparators 20, 21, and 22 compare each reference potential with the potential of the slider 8 to generate a throttle valve fully open signal, a throttle fully closed signal, and a pump start signal.

FIG. 3 shows the relationship between the intake flow rate Q (θ, n) and the potential of the slider 8, as well as the relationship between the throttle fully open and fully closed signals and the pump drive signal.

Here, θ represents the throttle opening, and n represents the engine speed.

According to this diagram, a pump start signal is issued when the intake flow rate reaches Qp, a fully closed throttle signal is issued when the intake flow rate is below Q■, and a fully open throttle signal is issued when the intake flow rate is above QF. That is clear.

What should be noted here is that the intake air flow rate Q is a function not only of the throttle opening but also of the engine rotation n.

FIG. 4a shows the relationship between engine speed 0, throttle valve opening θ, and intake flow rate Q using equal intake flow rate lines and equal throttle valve opening curves.

In FIG. 4a, the solid line is the equal throttle valve opening curve, and the broken line is the equal intake flow rate curve.

FIG. 4 is a graph based on the graph of FIG. 4a, showing the relationship between the throttle valve opening θ and the intake air amount Q using the engine speed n as a parameter.

Here, the throttle valve fully open state refers to a state in which the throttle valve opening degree is approximately 400 to 500 degrees or more, and the fully open state generally refers to a state in which the throttle valve opening degree is approximately 3 degrees or less. In the graph, the area to the right of broken line B can be defined as a fully open signal area, and the area to the left of broken line C can be defined as a fully closed signal area.

It is clear from this graph that the throttle valve opening is at a predetermined angle (
It can be seen that the intake flow rate is hardly affected by the engine speed below the angle (normally about 15 degrees).

The intake flow rate detector of the present invention approximates the fully open throttle state by an intake flow rate of a certain value or more, and for example, the region to the right of the dotted line B is regarded as the fully open throttle state.

However, the full throttle opening range is actually the range where the intake flow rate is QF1 or more when the engine speed is low, and the range where the intake flow rate is QF2 or more when the engine speed is low, so the throttle valve is fully open depending only on the intake flow rate. Errors occur when the state is detected.

It can be seen that in order to eliminate such errors in the intake flow rate detector of the present invention, the reference potential applied to the comparator 20 can be increased in accordance with the increase in engine speed.

On the other hand, near the dotted line C in the throttle valve fully closed signal region, the intake flow rate is hardly affected by the magnitude of the engine speed, so the above-mentioned criteria are used to generate the fully closed signal and pump start signal. Correction of potential is not required in practice.

Of course, depending on the case, it may be possible to make fine corrections to the reference potential depending on the engine speed in order to generate a fully closed signal.

From the above, it is clear that according to the intake flow rate detector of the present invention, the throttle valve switch and the fuel pump switch can be omitted, resulting in cost reduction.

In addition, the fuel pump switch had to be operated with a small amount of air, making adjustment particularly difficult, but the intake flow rate curver of the present invention can eliminate this difficulty. .

Although the present invention has been described above with reference to preferred embodiments, it is clear that various modifications can be made within the technical scope of the present invention.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the prior art. FIG. 2 is a block diagram showing one embodiment of the present invention. 3 and 4 are diagrams showing the characteristics of the embodiment shown in FIG. 2. Explanation of symbols of main parts 1...Intake pipe, 2...
・・・・Throttle valve, 6・・・・Throttle valve switch, 7・・・・−・Weir plate, 9・・・・ Potentiometer, 10・・・・Fuel pump switch, 1
8...Fuel pump motor, 20.21,22.
...Comparator.

Claims (1)

[Claims] 1 An output voltage corresponding to the angular position of a dam plate for measuring intake flow rate arranged in an intake conduit of an in-vehicle internal combustion engine equipped with a fuel injection device including an injection valve drive pulse generation circuit is applied to the slider of a potentiometer. an intake flow rate detector configured to generate the output voltage to the injector drive pulse generation circuit, and divide the voltage supplied to the potentiometer to generate a predetermined reference voltage. An intake flow rate detector comprising a voltage dividing circuit and a signal generating means for generating a fuel pump drive signal by comparing the output voltage with the predetermined reference voltage.