JPS6215482Y2 - - Google Patents

Description

[Detailed description of the invention] This invention detects whether the engine is rotating or stopped, drives the fuel pump when the engine is running, and deactivates the fuel pump when it is stopped, thereby cutting off unnecessary fuel in the event of a vehicle accident, for example. , relates to a fuel pump control device for preventing vehicle fires.

This type of device generally takes the ignition signal as input,
Whether the engine is running or stopped is detected based on the presence or absence of an ignition signal. A conventional fuel pump control device will be explained using FIG. 1 and FIG. 2.

FIG. 1 is a circuit diagram showing an example of a conventional fuel pump control device, in which 1 is an ignition coil, 2 is an ignition device that intermittents the current of the ignition coil 1 to generate an ignition spark, and 3 is an ignition signal. This is a timer circuit that is triggered every time. The output of this timer circuit 3 is supplied to the base of a transistor 4. The emitter of the transistor 4 is grounded, the collector is connected via the diode 5 to the Ig contact 10a of the key switch 10, and the movable contact of the key switch 10 is grounded via the battery 11.

ST contact 10b of key switch 10 is connected to fuel pump 9 and normally open contact 6a of relay 6 via diode 7. The coil of the relay 6 is connected in parallel with the diode 5, and the common terminal of the relay 6 is connected to the Ig contact 10a of the key switch 10. Thus, the timer 3, transistor 4, diodes 5, 7, and relay 6 constitute a fuel pump control device 8.

Next, the operation of the fuel pump control device shown in FIG. 1 will be described with reference to the time chart shown in FIG. 2. 2a and 2b show when the engine is running at low speed, and FIGS. 2c and 2d show when the engine is running at high speed. 2a and 2c show the ignition signal, and FIGS. 2b and 2d show the output of the timer circuit 3. FIG.

When the ignition signal from the ignition device 2 is applied to the timer circuit 3, the timer circuit 3 is triggered, and as shown in FIG. 2b, the Tb output voltage becomes "H" for a certain period of time, turning on the transistor 4. , drives the relay 6 for a certain period of time Tb. Then, the normally open contact 6a of the relay 6 is closed, and the fuel pump 9 is driven only for a certain period of time Tb.

Here, as shown in FIGS. 2a and 2b, if the engine speed is low and the ignition signal interval Ta (FIG. 2a) is longer than the set time Tb of the timer circuit 3, the fuel pump 9 will not ignite. Set time for each signal
It becomes an intermittent energization state where it is driven only during Tb, but
When the engine speed is high and Tb>Ta, the fuel pump 9 is continuously driven as shown in FIGS. 2c and 2d.

Therefore, if the set time Tb of the timer circuit 3 is set to be longer than the ignition signal interval corresponding to the cranking rotation speed of the engine, the fuel pump 9 will be driven continuously from the time of cranking, and the engine will not rotate. During this time, the fuel pump 9 is driven and the necessary fuel is supplied.

When the engine stops, no ignition signal is applied, so the last ignition signal immediately before the engine stops is applied, and after the set time Tb has elapsed, the fuel pump 9
The operation stops and becomes the desired operation.

Regarding the above operation, if the charging state performance of the battery 11 is poor, the voltage during cranking becomes very low because the current required for the engine starter is large, and it becomes below the impression voltage of the relay 6, and the relay 6 cannot operate. There are cases where the normally open contact 6a does not close and the fuel pump 9 is not driven. For this reason, in the conventional device, a method is used in which the fuel pump 9 is driven from the ST contact 10b of the key switch 10 via the diode 7, as shown in FIG.

In this case, the current flowing to the fuel pump 9 is several amperes, and when the starter is off, a large negative surge voltage due to the inductance of the starter is applied in the opposite direction of the diode 7, so the diode 7 has a large current capacity. There is a drawback that a high-voltage element is required.

The object of this invention is to provide a fuel pump control device that can drive the fuel pump only with a relay even during engine cranking without requiring the large current capacity and high withstand voltage elements of the conventional devices.

Next, an embodiment of the fuel pump control device of this invention will be described with reference to FIG. In FIG. 3, in order to avoid duplication when describing the configuration, parts that are the same as those in FIG. 1 are given the same reference numerals, and their explanation will be omitted, and only the parts that are different from those in FIG. 1 will be described.

As is clear from comparing FIG. 3 with FIG.
The output of the timer circuit 3 is configured to be supplied to the base of the transistor 4 via the inverter 12, and the relay 6 is configured to supply operating power from the battery 11 to the fuel pump 9 via the normally closed contact 6b. It is configured. Further, the normally open contact 6a of the relay 6 is configured to be disconnected from the circuit.
Other parts are the same as in FIG.

With this configuration, the timer circuit 3
The operation is the same as the conventional operation shown in FIG. 1, and when the engine is rotating at low speed, the output shown in FIG.

In the embodiment shown in FIG. 3, since the output voltage of the timer circuit 3 is inverted by the inverter 12, the operation of the transistor 4 and the relay 6
The operation is opposite to that shown in Fig. 1, and the relay 6 is turned off while the engine is rotating or cranking, and the fuel pump 9 is driven via the normally closed contact 6b of the relay 6, and when the engine is stopped. is relay 6
is turned on, and the operation of the fuel pump 9 is stopped.

In this operation, since the fuel pump 9 is driven via the normally closed contact 6b when the relay 6 is off, it has no relation to the applied voltage of the relay 6, and even if the power supply voltage drops significantly during cranking. It can be driven by relay 6.

Furthermore, when the engine is stopped, the power supply voltage will not drop significantly and become below the voltage applied to the relay 6 as it would during cranking, and the relay 6 can be turned on, allowing the fuel pump 9 to turn on. The operation will be stopped. Therefore, in the event of a vehicle accident or the like, unnecessary fuel can be cut off and the desired operation to prevent a vehicle fire can be performed.

As described above, according to the fuel pump control device of this invention, the relay is turned off while the engine is rotating or cranking by the output of the timer circuit that is triggered for each ignition signal, and the normally closed contact of the relay is turned off. When the engine is stopped, the relay is turned on to stop the fuel pump from operating, so a diode with a large current capacity and high voltage resistance is used to power the fuel pump during cranking. This can be done without any particular need, and also has the feature that there is no need for wiring from the ST contact of the key switch to the fuel pump control device.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a conventional fuel pump control device, Fig. 2a is a diagram showing an engine ignition signal at low engine speed, and Fig. 2 is a circuit diagram showing a conventional fuel pump control device at low engine speed. Figure 2c is a diagram showing the output signal of the timer circuit. Figure 2c is a diagram showing the engine ignition signal when the engine is running at high speed. Figure 2d is the output signal of the timer circuit in a conventional fuel pump control device when the engine is running at high speed. FIG. 3 is a circuit diagram of an embodiment of the fuel pump control device of this invention. 1... Ignition coil, 2... Ignition device, 3... Timer circuit, 4... Transistor, 5, 7... Diode, 6... Relay, 6a... Normally open contact, 6b
...Normally closed contact, 8...Fuel pump control device, 9...
...Fuel pump, 10...Key switch. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] A timer circuit that is triggered every time the engine ignites and outputs an output for a predetermined period of time, and is controlled by the output of this timer circuit and is deenergized while the engine is rotating or cranking to supply power to the fuel pump via a normally closed contact. A fuel pump control device comprising a relay that is energized to stop power supply to the fuel pump while the engine is stopped.