JPS6037313B2 - Fuel pump drive device for electronically controlled fuel injection system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronically controlled fuel injection system for an internal combustion engine, and more particularly to a fuel pump drive system in such a system.

An electronically controlled fuel injection device for an internal combustion engine includes an injection valve drive circuit that generates a drive pulse that intermittently opens an electromagnetically operated fuel injection valve to inject a desired amount of fuel into an intake manifold. ing.

The injection drive circuit adjusts the period and duty ratio of the drive pulse according to the intake air amount, engine speed, and other engine parameters. A fuel pump is also provided that supplies fuel to the injection valve under a predetermined pressure. - Conventional fuel pump drive devices always drive the fuel pump while the engine is operating.

Therefore, the switching element for driving the fuel pump had to have a large capacity and high heat resistance. Furthermore, since the fuel pump always rotates at a substantially constant rate regardless of whether the vehicle is idling or driving, there is a problem in that the rotational sound of the fuel pump is annoying to the driver when the vehicle is idling. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a fuel pump drive device that reduces the capacity of a fuel pump drive switching element and suppresses pump drive noise during idling.

The fuel pump drive device according to the present invention is configured to supply electric power corresponding to the injection valve drive pulse to the fuel pump drive motor, and drives the fuel pump in approximately proportion to the amount of fuel supplied. This is efficient and reduces unpleasant pump rotation noise to a minimum of 4.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 schematically shows an electronically controlled fuel injection valve drive circuit.

This fuel injection valve drive circuit uses the engine's ignition pulse P1 and the intake air amount detection signal Q from the intake air amount sensor.
, and other engine parameters, and an arithmetic circuit 1 that outputs a basic pulse Tp in accordance with the outside parameters of the engine, and outputs the output of the arithmetic circuit 1 under predetermined conditions such as when starting the engine, into a final output pulse that takes into account the amount of fuel increase, that is, the injection valve drive. Pulse Ti
and an increase circuit 2 for converting into. The commotion pulse Ti is
It is supplied to the solenoid of the injection valve to intermittently engage the injection valve. FIG. 2 shows a fuel pump drive device 10 that is an embodiment of the present invention.

This fuel pump drive device 1 includes an OR circuit 11 that outputs the logical sum of the basic pulse Tp of the injection valve drive device and the injection valve drive pulse shown in FIG. 1, and an integral that integrates the output of the OR circuit 11. When the outputs of the circuit 12 and the integrating circuit are smaller than the reference voltage V7, a logic "0" is output, for example, and V7
a comparator circuit 13 that outputs a logic "1" when the voltage exceeds 1, an adder circuit 14 that adds a predetermined voltage supplied via terminal AI within a predetermined time at engine start to the output of the comparator circuit 13; and a drive circuit 15 that supplies a fuel pump drive signal to the fuel pump motor in accordance with the output. FIG. 3 shows the diagram of FIG. 2.

This figure shows a specific circuit example of the block diagram, and the parts surrounded by dotted silver lines correspond to each block, and the same reference numerals as the corresponding blocks are given. That is, the diodes D1 and D2 form an OR circuit 11. The signal from the OR circuit 11 is supplied to the base of the transistor TI via a voltage dividing point BI of a voltage dividing circuit including resistors R7 and R8. A voltage corresponding to the collector voltage of the transistor TI is applied to the resistors R1, R4, and R.
6 to the negative terminal of the operational amplifier OPI. On the other hand, the positive terminal of the operational amplifier OPI is connected to a resistor R1,
A predetermined voltage is supplied by a voltage dividing circuit consisting of R2, R3 and R5. Operational amplifier OPI constitutes an integrator together with capacitor CI. Output terminal B of operational amplifier OPI
2 is connected to the positive input terminal of the operational amplifier PP2 of the comparison circuit 13. A negative input terminal of the operational amplifier 13 is connected to a voltage dividing point B3 of a voltage dividing circuit including resistors R9 and RIO. The output terminal B4 of the operational amplifier OP2 is connected to the anode of the diode D3 of the adder circuit 14. Diode D3
The cathode of is connected to the cathode of diode ○4 via resistor RII. The anode of diode ○4 is connected to terminal AI. The cathode of diode 04 is
It is connected to the base of the transistor T2 via the resistor R12 of the drive circuit 15. When transistor T2 is turned on, pump motor M is driven. FIG. 4 shows waveforms of voltage changes at various parts of the circuit shown in FIG.

Now, if the waveforms of the basic pulse Tp and the driving pulse Ti are as shown in FIG. 4, the voltage at the BI point will be as shown in FIG. When the transistor TI is turned on, the potential at point B2 gradually increases, and when the transistor TI is turned off, the potential at point B2 decreases. Capacitor CI is discharged through the path of resistors R4, R2, and R3 until the potential at point B2 and the power supply voltage are balanced. The potential at the BI point rises again and the transistor TI
When turned on, the above operation is repeated. Next, at the time of fuel cut operation, the drive pulse T of the injection valve drive device
Although the pulse width of i is reduced to about 200 ys, the pulse width of the basic pulse Tp is kept quite large. This situation is shown in Figure 5, A, Mouth. Changes in potential at points B1, B2, B3, and B4 in this case are shown in FIG. 5, C, 2, and E. Therefore, for example, pulse T
Even when the pulse width of i becomes extremely small, sufficient power is provided to the fuel pump motor.

On the other hand, a predetermined voltage corresponding to the rise of the motor start signal for starting the engine is supplied to the terminal AI of the adder circuit 14, and the transistor T2 continues to be turned on during that time regardless of the change in the potential at point B4.

As is clear from a comparison of the waveforms in FIG. 4 and FIG. Therefore, it is efficient and the transistor T2
It is possible to suppress the temperature rise of the pump, and furthermore, it is possible to suppress the pump drive noise during idling.

FIG. 6 shows another embodiment of the invention.

This embodiment is a control device that controls a fuel pump motor using only the injection valve drive pulse Ti. In this device, a multi-pipulator 20 generates a square wave pulse signal of a constant frequency. On the other hand, the discrimination circuit 21 generates a logic "1" signal when the pulse width of the pulse Ti exceeds a predetermined value. The output pulse of the indexing multipipulator 20 is supplied to an adder circuit 14' via a gate circuit 22. The output of the discrimination circuit 21 is also supplied to the addition circuit 14', where it is added to the signal from the terminal AI and the signal from the gate circuit 22, and is supplied to the pump motor drive circuit 15. Input terminals A2 and A3 of the gate circuit 22 are supplied with each oil pressure signal and alternator signal.

The oil pusher signal is supplied when the oil pump is driven by the engine rotation and the oil pressure reaches a predetermined level or higher, and the alternator signal is supplied when the generator is rotated by the engine rotation. In the fuel pump drive circuit shown in FIG. 6, when the engine is started, a signal generated at the terminal AI turns on the transistor T3, and the pump motor starts.

Next, by supplying the oil pusher signal or the alternator signal to the terminals A2 and A3, the gate circuit 22
The signal from the free-running multipipulator 20 is added to the adder circuit 14.
’. Thereafter, when the pulse width of the injector drive pulse Ti increases and the engine load increases and the discrimination circuit 21 issues a logic "1" signal, the transistor T3 continues to be turned on and supplies a large amount of power to the pump motor M. When the engine load becomes smaller, the pump motor is again driven with a smaller average power in response to the pulse signal from the self-propelled multi-purpose pump 20. From the above, it is clear that in the fuel pump drive device according to the present invention, the fuel pump is driven in accordance with the injection valve drive pulse, so the fuel pump is driven in accordance with the desired amount of fuel. It is possible to avoid wasteful use, and it is also possible to suppress the temperature rise of the switching elements used, so it is possible to increase the capacity and extend the life of the switching elements.

Furthermore, it is possible to suppress unpleasant pump rotation noise during idling.

[Brief explanation of the drawing]

FIG. 1 is a block diagram schematically showing a fuel injection valve shift device, FIG. 2 is a block diagram of an embodiment of the present invention, and FIG.
FIG. 2 is a circuit diagram showing a specific circuit example of the device; FIGS. 4 and 5 are waveform diagrams of voltage changes at each part of the circuit in FIG. 3; FIG. 6 is a circuit showing another embodiment of the present invention. figure. Explanation of symbols of main parts, 11...OR circuit, 12.
...Integrator circuit, 13...Comparison circuit, 14,14'...
- Addition circuit, 15... Drive circuit, 20... Self-running multipipulator, 21... Discrimination circuit, 22... Gate circuit. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1 An electrically operated fuel injection valve that injects fuel into a cylinder of an on-vehicle internal combustion engine to start the engine in response to an engine start signal, a fuel pump that pumps fuel to the fuel injection valve, and a fuel injection valve that A fuel pump drive device in an electronically controlled fuel injection device including a fuel injection valve drive circuit that generates intermittently driven drive pulses, and a pulse generation circuit 20 that generates a pulse signal;
a pulse width discrimination circuit 21 that generates an on signal when the pulse width of the drive pulse exceeds a predetermined value; an adder circuit 14' that superimposes the pulse signal, the on signal, and the engine start signal; A fuel pump electric device characterized by having a pump motor drive circuit 15 that supplies a voltage according to the output to a motor that drives the fuel pump.