JPH06147046A - Engine fuel pump controller - Google Patents

Abstract

PURPOSE:To eliminate an adverse effect due to a noise at the time of switching and a perform a stable fuel supply by way of avoiding any voltage drop at the time of starting an engine. CONSTITUTION:A fuel pump control circuit 12 is being installed in space between a battery and a pump motor of a fuel pump. In this fuel pump control circuit 12, a first transistor 24 and a second transistor 25 are connected to each other in a parallel manner, and a noise eliminator circuit 26 is connected to the first transistor 24 in series and to the second transistor 25 in parallel, respectively. In addition, a timer control circuit 30 keeps the second transistor 25 in an on-state (100% in duty ratio) intact at the time of starting an engine, while it controls the first transistor 24 at the duty ratio conformed to an engine load state by an electronic control unit (engine load detection) in time of normal operation after the engine started.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel pump control device for an engine which controls the flow rate of a fuel pump by controlling the duty of a switching element.

[0002]

2. Description of the Related Art Conventionally, an engine fuel pump control device has been disclosed in which a drive current flowing through a fuel pump is changed according to an operating state of the engine. For example, in the control device disclosed in Japanese Utility Model Laid-Open No. 61-55162, when the load condition of the engine is high, a high driving current is passed through the fuel pump to operate at a high flow rate.
When the load condition of the engine is low, a low drive current was passed through the fuel pump to operate at a low flow rate.

A switching element is generally used in a control circuit incorporated in a control device for an electric fuel pump. By controlling the duty of the switching element, the current value to the fuel pump motor is controlled and the flow rate of the fuel pump is adjusted. Further, the switching control circuit as described above has a noise elimination circuit incorporated therein for eliminating switching noise generated during the switching operation (on / off operation), and the noise elimination circuit removes the noise. By doing so, adverse effects on other devices caused by noise being transmitted through the power supply line were prevented.

[0004]

However, in the above-described conventional fuel pump control device for an engine, when the battery is weak and the battery voltage is low, there is a problem in that the engine may fail to start. there were. That is,
In the above-described conventional control circuit, the noise removal circuit incorporates a resistor having a high resistance value. Therefore, when the battery voltage is reduced, the noise removal circuit causes the voltage to be further reduced. Therefore, at the time of starting the engine, the current value applied to the motor is reduced and the amount of fuel supplied from the fuel pump to the engine is also reduced, although a relatively large flow rate is required. As a result, in the worst case, a situation of engine start failure will occur.

The present invention has been made in view of the above problems, and its purpose is to eliminate the adverse effect of noise during switching and to avoid a voltage drop at the time of engine startup to stabilize the operation. An object of the present invention is to provide a fuel pump control device for an engine that can supply fuel.

[0006]

In order to achieve the above object, the present invention relates to a fuel pump control apparatus for an engine in which the flow rate of the fuel pump is controlled by controlling the duty of a switching element. A first switching element provided between the motor and the motor, a noise removal circuit connected in series to the first switching element, and a second switching element connected in parallel to at least the noise removal circuit. A first control means for holding the second switching element in an ON state at the time of engine startup; and a second control element for making the second switching element in an OFF state after the engine startup, and at a predetermined duty ratio. And a second control means for controlling the switching element of 1.

[0007]

According to the present invention, the first control means holds the second switching element in the ON state when the engine is started. The second control means controls the second
The switching element is turned off and the first switching element is controlled at a predetermined duty ratio.

That is, when the engine is started, the second switching element is always in the ON state, so that the power supply line from the battery to the motor bypasses the noise removing circuit, and the noise removing circuit causes the battery voltage to drop. Absent. As a result, the maximum current flows from the battery to the fuel pump motor. On the other hand, after starting the engine,
The switching element performs a switching operation (on / off operation), and a current is supplied from the battery to the fuel pump motor at the timing when the element is turned on. Also, at this time,
Noise generated by the switching operation of the switching element is removed by the noise removing circuit.

[0009]

【Example】

(First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a diagram showing a schematic structure of a fuel pump control system for an engine in this embodiment. A gasoline injection engine (hereinafter, simply referred to as an engine) 1 is mounted on a vehicle, and an electric fuel pump 2 is connected to the engine 1. The fuel pump 2 is provided with a pump motor 3. Then, as the pump motor 3 is driven, fuel is supplied from the fuel pump 2 to the engine 1, and the fuel is injected into the combustion chamber (not shown) in the engine 1 via a delivery pipe and an injector (both not shown). It is supposed to be done.

The fuel pump 2 is an in-tank type,
It is arranged in the fuel tank 4. A filter 6 is attached to the lower portion of the fuel pump 2, and the fuel is sucked through the filter 6. A discharge pipe 7 is attached to the upper portion of the fuel pump 2, and the fuel is supplied to the delivery pipe (not shown) of the engine 1 through the discharge pipe 7. A bracket 9 is fixed to the fuel pump 2, and a flange 8 is fixed to the bracket 9. The flange 8 is attached to the outer wall of the fuel tank 4 with a screw 11 via a rubber packing 10.

Further, the fuel pump 2 includes a bracket 1
3, a fuel pump control circuit 12 is attached, and the control circuit 12 is connected to the pump motor 3 by wiring 14.
Is electrically connected to. Further, the fuel pump control circuit 12
Are connected to three wires 17 to 19, of which the wire 17 is connected to an electronic control circuit (hereinafter referred to as ECU) 15 described later, the wire 18 is connected to a battery 20, and the wire 19 is It is grounded. That is, electric power is supplied to the pump motor 3 from the battery 20 via the wiring 18.

On the other hand, the ECU 15 is connected with various sensors such as an engine speed sensor 16 for detecting the speed of the engine 1. Then, the ECU 15 detects the operating load state of the engine 1 based on the detection signal of the engine speed sensor 16 and the gear ratio of the transmission (not shown), and the load detection signal is sent via the wiring 17 to the fuel pump control circuit 12 Output to.

FIG. 1 is a diagram showing an electrical configuration of the fuel pump control circuit 12. As shown in the figure, the fuel pump control circuit 12 is provided with a battery connection terminal 22 connected to the battery 20 side and a fuel pump connection terminal 23 connected to the pump motor 3 side of the fuel pump 2. There is.
In the control circuit 12, a first transistor 24 as a first switching element and a second transistor 25 as a second switching element are provided between the battery connection terminal 22 and the fuel pump connection terminal 23. It is connected in parallel. These transistors 24 and 25 are NP
It consists of an N-transistor, and turns on when a voltage (H level signal) of a predetermined value or higher is applied to the base terminal.
From collector (battery side) to emitter (fuel pump side)
Is allowed to be energized.

A noise removing circuit 26 is connected in parallel with the second transistor 25 between the first transistor 24 and the battery connection terminal 22. The noise removing circuit 26 includes an inductor 26a and a capacitor 26b.
It is a publicly known thing constituted by. Then, the noise removing circuit 26 sets the first transistor 24 to a high frequency (20
The switching noise generated when the switching operation (on / off operation) is performed at (kHz or more) is prevented, and adverse effects (malfunction, etc.) on other electric devices, control circuits, etc., which are generated by the noise transmitted through the power supply line are prevented.

Further, in the fuel pump control circuit 12, the battery connection terminal 22 is provided with a frequency conversion circuit 28 and a PWM (phase conversion) via a circuit drive constant voltage circuit 27.
The circuit 29, the timer control circuit 30, and the protection circuit 31 are connected. Among them, the circuit driving constant voltage circuit 27 converts the battery voltage into a constant voltage and outputs the voltage to each of the circuits 28 to 28.
It supplies to 31. In addition, the frequency conversion circuit 28
Inputs an engine load detection signal (ECU signal) output from the ECU 15. Then, the frequency conversion circuit 28 and the PWM circuit 29 generate a duty ratio signal according to the load state of the engine 1, and the PWM circuit 29 outputs the duty ratio signal to the timer control circuit 30.

Base terminals of the first and second transistors 24 and 25 are connected to the timer control circuit 30. A key switch 32 is connected to the timer control circuit 30, and when the key switch 32 is turned on (at the start of cranking of a starter motor (not shown)), the ON signal is input to the timer control circuit 30. It is like this. In this embodiment, the timer control circuit 3
0 constitutes a first control means and a second control means.

The protection circuit 31 includes a first transistor 24.
Is to prevent overheating and protect the transistor 24. That is, a temperature compensation resistor (not shown) is attached to the first transistor 24, and the first transistor 24 is overheated (for example, 1
When the temperature of 50 ° C. or higher is detected, the protection circuit 31 sets the base voltage to the first transistor 24 to the L level and forcibly turns off the transistor 24. Since the second transistor 25 is turned on only when the engine is started (when the temperature is low), the protection circuit is not required.

Next, the operation of the engine fuel pump control system of the present embodiment will be described with reference to the time chart of FIG. In FIG. 3, the timing of t1 indicates the time when the key switch is turned on, that is, the start of cranking of the starter motor (not shown) (the start of engine startup), and the timing of t2 indicates the end of cranking, that is, after engine startup. It indicates the time when a predetermined time has elapsed (at the end of engine startup).

First, at the timing of t1, when the key switch 32 is turned on, a voltage is applied from the battery 20 to the fuel pump control circuit 12, and each circuit in the control circuit 12 operates. The timer control circuit 30 outputs an L level signal to the first transistor 24 to turn off the transistor 24. Also, the timer control circuit 30
Outputs an H level signal (duty ratio “100%”) to the second transistor 25,
Hold 5 on. Therefore, the flow rate of fuel delivered from the fuel pump 2 is maximized, and the engine 1 is supplied with sufficient fuel necessary for starting. In addition, during the start-up period of the engine 1 (timing of t1 to t2), as shown in FIG.
At, a current flows as shown by the alternate long and short dash line, and the filter removal circuit 26 is bypassed. As a result, no voltage drop occurs due to the filter removal circuit 26.

On the other hand, when a predetermined time (starting period) has passed, t
When the timing of 2 comes, the timer control circuit 30
The output signal to the transistor 25 is changed from the H level (duty ratio “100%”) to the L level signal (OFF signal). In addition, the timer control circuit 30 includes the first transistor 2
4 outputs a predetermined duty ratio signal. This duty ratio corresponds to the engine load detection signal (ECU
Signal), and the higher the load of the engine 1 (for example, when climbing a slope), the higher the duty ratio. The first transistor 24 is ON / OFF controlled according to the duty ratio signal, and the pump motor 3 drives the fuel pump 2 only when the first transistor 24 is in the ON state (H level).
Fuel is delivered from.

After the timing of t2, the voltage of the battery 20 is applied to the first transistor 24 through the noise removing circuit 26 as shown by the chain double-dashed line in FIG. Therefore, the first transistor 24
Even if switching noise occurs due to the switching operation (ON / OFF operation), the noise is removed by the noise removing circuit 26, and the noise is not transmitted to other circuits or the like through the power supply line.

As described in detail above, in the engine fuel pump control apparatus of this embodiment, the fuel pump control circuit 12 is provided between the battery 20 and the pump motor 3 of the fuel pump 2. In the fuel pump control circuit 12, the first transistor 24 and the second transistor 25 are connected in parallel, and the noise removal circuit is connected in series with the first transistor 24 and in parallel with the second transistor 25. 26 was connected. The timer control circuit 30 turns off the first transistor 24 and holds the second transistor 25 on (duty ratio "100%") when the engine is started. In the normal operation after the engine is started, the reference numeral 30 turns off the second transistor 25 and controls the first transistor 24 at a duty ratio according to the load state of the engine 1 by the ECU 15.

As a result, when the engine is started, the noise removal circuit 26 is bypassed to avoid a drop in the battery voltage, and a sufficient amount of fuel required for starting the engine 1 is always supplied. Further, during normal operation after the engine is started, it is possible to always supply the engine 1 with an amount of fuel corresponding to the engine load state, and to eliminate noise generated due to the switching operation (on / off operation) of the first transistor 24. Therefore, stable fuel pump control becomes possible. (Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, only the differences from the first embodiment will be described.

FIG. 4 is a diagram showing the electrical construction of the fuel pump control circuit 12 in the second embodiment, and FIG.
6 is a time chart according to the operation of the timer control circuit 30. In FIG. 5, the timing of t3 indicates the time when the key switch is turned on (when the engine is started), and the timing of t4 indicates the time when the engine starts.

As shown in FIG. 4, the first transistor 2
4 and the second transistor 25 are connected in series. In addition, the noise removing circuit 26 uses the second transistor 2
Only 5 are connected in parallel.

When the key switch 32 is turned on at the timing of t3 in FIG. 5, the timer control circuit 30
Outputs an H level (duty ratio “100%”) signal to the first and second transistors 25, and holds the first and second transistors 25 in the ON state. At this time, as shown by the alternate long and short dash line in FIG.
Current flows from 0 to the pump motor 3 of the fuel pump 2.
Then, the flow rate of fuel delivered from the fuel pump 2 becomes maximum, and the engine 1 is supplied with sufficient fuel necessary for starting. At this time, the filter removal circuit 26
Is bypassed, and no voltage drop occurs due to the filter removal circuit 26.

On the other hand, at the timing t4 in FIG. 5,
The timer control circuit 30 changes the output signal to the second transistor 25 from H level (duty ratio “100%”) to L level.
Set to level (off signal). Also, the timer control circuit 30
At the same time, outputs a duty ratio signal to the first transistor 24 according to the engine load detection signal (ECU signal) at that time. Then, only when the first transistor 24 is in the ON state, the pump motor 3 is driven and the fuel is fed from the fuel pump 2.

After the timing of t4, the voltage of the battery 20 is applied to the first transistor 24 through the noise removing circuit 26 as shown by the chain double-dashed line in FIG. Therefore, the first transistor 24
The noise removal circuit 26 removes the switching noise generated by the switching operation (ON / OFF operation).

As described above, in the fuel pump control system for the engine of the second embodiment, in the fuel pump control circuit 12, the first transistor 24 and the second transistor 2 are provided.
5 is connected in series, only the second transistor 25,
The noise removal circuit 26 was connected in parallel. The timer control circuit 30 keeps the first transistor 24 and the second transistor 25 in the ON state (duty ratio “100%) when the engine is started. During the normal operation, the second transistor 25 is turned off, and the first transistor 24 is controlled with the duty ratio according to the load state of the engine 1 by the ECU 15.

As a result, when the engine is started, the noise removal circuit 26 is bypassed to avoid a drop in the battery voltage, and a sufficient amount of fuel required for starting the engine 1 is always supplied. Further, during normal operation after the engine is started, it is possible to always supply the engine 1 with an amount of fuel corresponding to the engine load state, and to eliminate noise generated due to the switching operation (on / off operation) of the first transistor 24. Therefore, stable fuel pump control becomes possible.

As described above, also in the second embodiment, as in the first embodiment, the adverse effect due to the noise generated during the switching operation of the first transistor 24 is prevented, and further, the voltage drop at the time of starting the engine. Will be avoided and a stable fuel supply will be performed.

In the embodiment described above, the duty of the first switching element is controlled according to the load condition of the engine, but the discharge fuel pressure from the fuel pump, the return fuel amount from the fuel injection device, etc. The duty may be controlled according to the above.

[0034]

As described above, according to the present invention, it is possible to eliminate the adverse effect of noise at the time of switching and to avoid the voltage drop at the time of starting the engine to perform stable fuel supply.

[Brief description of drawings]

FIG. 1 is an electrical configuration diagram of a fuel pump control circuit according to a first embodiment.

FIG. 2 is a configuration diagram showing a fuel pump control device for an engine.

FIG. 3 is a time chart in the first embodiment.

FIG. 4 is an electrical configuration diagram of a fuel pump control circuit according to a second embodiment.

FIG. 5 is a time chart in the second embodiment.

[Explanation of symbols]

1 ... Engine, 2 ... Fuel pump, 3 ... Pump motor, 2
0 ... Battery, 24 ... First transistor as first switching element, 25 ... Second transistor as second switching element, 26 ... Noise removal circuit, 3
0 ... Timer control circuit as first and second control means.

Claims (1)

[Claims] 1. A fuel pump control device for an engine, wherein a flow rate of a fuel pump is controlled by controlling a duty of a switching element. A first device provided between a battery and a fuel pump motor.
Switching element, a noise removing circuit connected in series with the first switching element, and a second noise removing circuit connected in parallel with at least the noise removing circuit.
Switching element, first control means for holding the second switching element in the ON state at the time of engine startup, and after the engine startup, the second switching element is in the OFF state and a predetermined duty ratio is maintained. And a second control means for controlling the first switching element.