JPH0221591Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applicable to automobile engines, particularly gasoline engines equipped with an electronically controlled fuel injection device.
The present invention relates to a fuel pump control device that controls the drive of a fuel pump.

<Prior art> As a conventional control device for this type of fuel pump, there is one shown in FIG.
(See No. 121359, etc.)

This is achieved by interposing a power transistor 2 in the current supply circuit to the fuel pump motor 1, and controlling the conduction of the power transistor 2 via the drive circuit 4 based on the duty ratio calculated from the required amount of fuel supplied by the microcomputer 3. It is designed to control the duty of non-conduction. In addition, the required supply amount of fuel is the basic injection amount Tp (=K・Q/N; K is a constant) of the fuel injection valve, which is calculated from the intake air flow rate Q and the engine rotation speed N in the electronically controlled fuel injection system. is used. UB indicates the power supply voltage.

Further, the control device controls the motor 1 based on the divided voltage Vs of the voltage dividing resistor Rs inserted in series with the motor 1.
The motor 1 is provided with an overcurrent detection means for detecting whether an overcurrent is flowing through the motor 1, and a disconnection detection means for detecting the presence or absence of a disconnection in the energizing circuit of the motor 1 based on the divided voltage Vs of the voltage dividing resistor Rs. . Then, the detection output Sg1 or Sg is output from either one of the two detection means.
2, the microcomputer 3 performs a self-diagnosis and drives the light emitting diode 5 to turn on.

Here, the overcurrent detection means is constructed using a voltage comparator CP1, and the disconnection detection means is constructed using a voltage comparator CP2. The divided voltage Vs of the voltage dividing resistor Rs is averaged by the resistor R4 and the capacitor C1, and then input to the non-inverting input (+) of the comparator CP1 and the inverting input (-) of the comparator CP2, respectively. The comparison reference voltage of each comparator CP1, CP2 is
It is obtained by dividing the power supply voltage UB using resistors R1, R2, and R3. The detection outputs Sg1 and Sg2 of both the detection means, that is, the comparison outputs of both the comparators CP1 and CP2, are input to the microcomputer 3 via the OR gate G1. Note that the components other than the motor 1 are mounted within the control unit 6.

<Problems to be solved by the invention> However, in the conventional fuel pump control device described above, the drive amount of the fuel pump motor 1 is controlled by the microcomputer 3 regardless of the state of the motor 1.
Since the setting is unilaterally based on a command from the side, for example, if a foreign object gets caught in the rotating part of the motor 1 or the pump, the rotational load of the motor 1 may increase abnormally, and this may occur. Even if an overcurrent flows through the motor 1, the light emitting diode 5 in the control unit 6 is only turned on, and the amount of drive of the motor 1 remains unchanged. Therefore, the overcurrent causes the motor 1 to
The overcurrent condition worsens as the resin part begins to melt, and eventually the power transistor 2 in the control unit 6 is likely to burn out.

Another problem is that there is no countermeasure against the fuel pump stopping due to foreign objects getting caught, resulting in engine stall.

The purpose of this invention is to prevent the above problems from occurring, and its purpose is to:
If motor 1 were to fail due to a load abnormality as described above,
When a situation occurs where an overcurrent flows,
The amount of drive of the motor 1 is automatically reduced, thereby protecting the motor 1 and the power transistor 2 in the control unit 6 from damage, and also providing relief in the event that the engine stops. An object of the present invention is to provide a fuel pump control device that makes it possible.

<Means for Solving the Problems> In order to achieve the above object, the present invention, as shown in FIG. In a fuel pump control device comprising a duty control means A that duty-controls the conduction/non-conduction of the power transistor 2 based on a duty ratio calculated from the required supply amount of Overcurrent detection means B detects whether overcurrent is flowing through the motor 1 based on the divided voltage of the resistor Rs, and disconnection detection means detects whether or not there is a disconnection in the energizing circuit based on the divided voltage. means C, engine determination means D for determining whether the engine is running or stopped, alarm means E for issuing an alarm when an overcurrent is detected or a disconnection is detected, and a means for reducing the duty ratio when the overcurrent is detected and the engine is rotating. A duty ratio reduction correction means F and a motor reversing means G for temporarily reversing the motor 1 when an overcurrent is detected and the engine is stopped are provided.

<Function> By the above means, when an overcurrent starts to flow to the fuel pump motor, the conduction of the power transistor is restricted and the amount of drive of the motor is reduced, and as a result, the motor and power transistor are Ensures protection from destruction. In addition, when an overcurrent flows,
When the engine has stopped, the motor is temporarily reversed, so any foreign matter that has gotten caught in the rotating part of the motor is removed, allowing the load on the motor to return to normal.

<Example> An example of the present invention will be described below with reference to FIGS. 2 and 3.

The hardware configuration is basically the same as the conventional one, but the software configuration is significantly different from the conventional one.

To explain the differences in hardware configuration with reference to Figure 2, the comparator as an overcurrent detection means
Comparison outputs Sg1 and Sg2 of CP1 and a comparator CP2 serving as a disconnection detection means are respectively input to a microcomputer 3. The microcomputer 3 outputs the two comparison outputs Sg
1. Based on Sg2, a control routine as shown in the flowchart of FIG. 3 is executed.

Further, the relay 7 and the transistor 8 constitute a polarity switching circuit for reversing the rotational direction of the fuel pump motor 1. This polarity switching circuit is adapted to be operated in response to a reverse rotation command signal from the microcomputer 3.

Further, apart from the light emitting diode 5 in the control unit 6, a warning lamp 9 is provided on or around the instrument panel of the automobile.

Here, the microcomputer 3 is the third
Operate according to the flowchart shown in the figure, and proceed to step 1.
calculates the duty ratio based on the required supply amount of fuel and outputs it. Then, in step 2, the signal Sg
The presence or absence of a wire breakage is determined based on level 2, and when a wire breakage is detected, the process proceeds to step 6, where the light emitting diode 5 in the control unit 6 is turned on and the warning lamp 9 is turned on to give a warning to the driver. If NO in step 2, it is determined in step 3 whether there is an overcurrent condition based on the level of signal Sg1, and if NO, the process returns to step 1.

When an overcurrent is detected, it is determined in step 4 whether the engine has stopped or not. If NO, the process proceeds to step 5, where the duty ratio of the pulse signal given to the power transistor 2 is corrected to reduce the amount of drive. do. In this way, by forcibly controlling the duty ratio of the output pulse signal, each of the power transistors 2 is reliably protected from thermal destruction due to overcurrent. Thereafter, the process proceeds to step 6 to issue an alarm.

If the engine has stopped, the transistor 8 is turned on in step 7, and the relay 7 is operated to reverse the motor 1. This is motor 1
This is because by temporarily reversing the rotation of the motor 1, the foreign matter that was caught in the rotating part of the motor 1 may be removed, and the load on the motor 1 may thereby return to normal. After this, in step 8, the transistor 8 is turned off and the motor 1 is rotated in the normal direction. Then, in step 9, it is determined whether or not the motor 1 is activated. If it is activated, the process returns to step 1; if it is not activated, the process proceeds to step 6, where an alarm is issued.

<Effects of the invention> As is clear from the above embodiments, in the fuel pump control device according to the invention, when an overcurrent flows to the motor due to a load abnormality, the drive amount of the motor is reduced. This has the effect that the motor and the power transistors in the control unit can be reliably protected from damage. In addition, if a foreign object gets caught in the rotating part of the motor or pump, causing the engine to stop, the motor is temporarily reversed, so the foreign object is removed and the engine is restarted. This has the effect of making it possible.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the configuration of the present invention;
The figure is a circuit diagram showing an embodiment of the present invention, FIG. 3 is a flowchart of the same, and FIG. 4 is a circuit diagram showing a conventional example. 1... Fuel pump motor, 2... Power transistor, 3... Microcomputer, 4...
Drive circuit, 6...control unit, 9...warning lamp.

Claims (1)

[Scope of utility model registration request] A fuel pump comprising a power transistor interposed in a current supply circuit to a motor of the fuel pump, and a duty control means for duty-controlling conduction/non-conduction of the power transistor based on a duty ratio calculated from a required supply amount of fuel. In the control device, overcurrent detection means detects whether or not an overcurrent is flowing through the motor based on a divided voltage of a voltage dividing resistor inserted in series with the motor; A disconnection detection means for detecting the presence or absence of a disconnection in the energized circuit, an engine determination means for determining whether the engine is rotating or stopped, an alarm means for issuing an alarm when an overcurrent is detected and a disconnection is detected, and an duty ratio reduction correction means for reducing the duty ratio during rotation;
1. A fuel pump control device comprising: motor reversing means for temporarily reversing the motor when an overcurrent is detected and the engine is stopped.