JP5000576B2 - Fuel pressure control system - Google Patents

Description

  The present invention relates to a fuel pressure control system that controls fuel pressure by changing an output of a fuel pump that pumps fuel to a fuel injection device of an engine or to a fuel injection device via a high-pressure pump.

A technique related to the above-described fuel pressure control system is described in Patent Document 1.
The fuel pressure control system described in Patent Document 1 includes a pressure detector that continuously detects the discharge pressure of the fuel pump, and the fuel is output when the output of the pressure detector exceeds a second pressure (high pressure). Stop supplying power to the pump motor. Further, when the output of the pressure detector is lower than the first pressure (low pressure), power supply to the motor is started with a predetermined power.

JP-A-2005-76465

In the fuel pressure control system described above, the fuel pressure is controlled by starting or stopping the power supply to the motor for the fuel pump. Therefore, when the engine load fluctuation is large, the fuel pressure can be accurately controlled. difficult.
Moreover, since the pressure detector is configured to continuously detect the discharge pressure of the fuel pump, the pressure detector is more expensive than, for example, a pressure switch.

  The present invention has been made to solve the above-described problems, and the problem to be solved by the present invention is to improve the controllability of the fuel pressure and to reduce the cost.

The above-described problems are solved by the inventions of the claims.
According to a first aspect of the present invention, in the fuel pressure control system that controls the fuel pressure by changing the output of the fuel pump that pumps the fuel, the fuel pressure is between the first set pressure and the second set pressure. A pressure detection means capable of detecting whether the pressure exceeds a set pressure or a pressure lower than the first set pressure; and the fuel when the fuel pressure exceeds a second set pressure upon receiving a signal from the pressure detection means The output of the motor for the pump is decreased by a certain amount, and when the fuel pressure is lower than the first set pressure, the output of the motor is increased by a certain amount, and the fuel pressure is between the first set pressure and the second set pressure. Control means for maintaining the output of the motor as it is, and selection means for selecting any one of the plurality of pressure detection means having different set pressure ranges. The output of the motor is controlled based on a signal from the pressure detection means selected by the stage .

According to the present invention, for example, when the amount of fuel injected from the injector decreases when the engine (vehicle) decelerates and the fuel pressure exceeds the second set pressure (high pressure side), the control means drives the fuel pump. The output of the motor to be reduced is reduced by a certain amount. As a result, the fuel pressure gradually decreases. Further, when the amount of fuel injected from the injector increases during acceleration of the engine (vehicle) and the fuel pressure decreases from the first set pressure (low pressure side), the control means outputs the output of the motor that drives the fuel pump. Increase by a certain amount. As a result, the fuel pressure gradually increases. Further, the control means drives the fuel pump when the amount of fuel injected from the injector becomes substantially constant during constant speed operation of the engine (vehicle) and the fuel pressure is between the first set pressure and the second set pressure. Maintain the current output of the motor.
Thus, the control means reduces the output signal value by a certain amount with respect to the current output signal when the fuel pressure exceeds the second set pressure, and sets the output signal value when the fuel pressure falls below the first set pressure. Increase by a certain amount. For this reason, the fuel pressure can be accurately controlled between the first set pressure and the second set pressure.
In addition, since the pressure detection means only needs to be able to detect whether the fuel pressure is between the first set pressure and the second set pressure, exceeds the second set pressure, or falls below the first set pressure, Compared with the method of continuously detecting the fuel pressure, the pressure detecting means can be simplified and the cost can be reduced. Furthermore, since the control means is configured to increase or decrease the output signal value by a certain amount with respect to the current output signal, the control means can be simplified compared to a method in which the output signal is continuously changed. Cost reduction can be achieved.
Also, for example, by using one pressure detection means in the high pressure range, using the other pressure detection means in the low pressure range, and selecting one of the selection means, the fuel pressure can be selected in the high pressure range, or It becomes possible to control in two steps in the low pressure range.

According to the invention of claim 2, the pressure detecting means includes the first switch and the second switch, and the first switch is turned on when the fuel pressure is lower than the first set pressure, and the fuel pressure is the first switch. The second switch is configured to be conductive when the pressure is lower than two set pressures.
For this reason, when the fuel pump is not operating, that is, when the fuel pressure is zero before operation, the first switch and the second switch are turned on. However, since the first switch or the second switch does not conduct in a failure state such as disconnection or foreign object biting, the failure of the pressure detection means can be confirmed before operation.
According to a third aspect of the present invention, in the fuel pressure control system that controls the fuel pressure by changing the output of the fuel pump that pumps the fuel, the fuel pressure is between the first set pressure and the second set pressure. A pressure detection means capable of detecting whether the pressure exceeds a set pressure or a pressure lower than the first set pressure; and the fuel when the fuel pressure exceeds a second set pressure upon receiving a signal from the pressure detection means The output of the motor for the pump is decreased by a certain amount, and when the fuel pressure is lower than the first set pressure, the output of the motor is increased by a certain amount, and the fuel pressure is between the first set pressure and the second set pressure. Control means for maintaining the output of the motor at present, and the pressure detection means includes a first switch and a second switch, and the fuel pressure is lower than the first set pressure. First Pitch becomes conductive, wherein said fuel pressure is the second switch is configured to be conductive when lower than the second set pressure.

  According to the present invention, the control accuracy of the fuel pressure can be improved and the cost can be reduced.

[Embodiment 1]
Hereinafter, the fuel pressure control system according to Embodiment 1 of the present invention will be described with reference to FIGS. The fuel pressure control system of this embodiment is a fuel pressure control system of a fuel supply device that is mainly mounted on a fuel tank mounted on an automobile or the like. FIG. 1 shows a schematic diagram of the fuel pressure control system. FIG. 2 is a flowchart showing the operation of the fuel pressure control system, and FIG. 3 is a graph showing the operation of each part of the fuel pressure control system. FIG. 4 is a schematic diagram showing a pressure switch in the fuel pressure control system, and FIG. 5 is an operation table of the pressure switch. FIG. 6 is a pressure switch according to the modified example, and FIGS. 7 and 8 are schematic views of the fuel pressure control system according to the modified example.

<About the schematic configuration of the fuel supply device>
Before describing the fuel pressure control system 40 according to the present embodiment, a fuel supply device including the fuel pressure control system 40 will be described.
As shown in FIG. 1, the fuel supply device is a device that pumps the fuel F in the fuel tank T to the injector 5 (fuel injection valve) of the engine. The fuel supply device is configured to operate based on a signal from an engine control unit ECU (hereinafter referred to as ECU), and includes a fuel pump 30, an intake filter 31, a high pressure filter 38, and the like installed at the bottom of the fuel tank T. It has.
The fuel pump 30 is a motor-integrated pump including an impeller-type pump portion 32 that sucks in fuel and pressurizes and discharges the fuel, and a motor portion 34 that drives the pump portion 32. The pump unit 32 sucks fuel through the suction filter 31, pressurizes the fuel by rotation of an impeller (not shown), and discharges the fuel into the motor unit 34. The fuel discharged into the motor section 34 cools the motor section 34 in the process of flowing upward, and is discharged from the discharge port 36 after lubricating and cleaning the rotating part.
The fuel discharged from the motor part 34 of the fuel pump 30 is guided to each injector 5 via the fuel supply pipe 7 outside the tank and the delivery pipe 8 after the motor foreign matter in the fuel is captured by the high-pressure filter 38. The fuel is injected from each injector 5 into a combustion chamber (not shown) of the engine.

<About fuel pressure control system 40>
The fuel pressure control system 40 includes a fuel pump controller FPC (hereinafter referred to as FPC) installed on the upper surface side of the fuel tank T, and a pressure switch 43 for detecting the fuel pressure on the outlet side of the high-pressure filter 38. Yes.
As shown in FIG. 4A, the pressure switch 43 is a double switch composed of a first switch 45 for low pressure and a second switch 46 for high pressure. Here, since the first switch 45 and the second switch 46 have the same structure and differ only in the set pressure, the configuration of the first switch 45 will be described as a representative.
The first switch 45 of the pressure switch 43 includes a cylindrical housing 47 and a disk-shaped diaphragm 48 that partitions the housing 47 in the axial direction. A pressure introduction port 47 p is formed in one room (upper room) in the housing 47 partitioned by the diaphragm 48. At the center of the diaphragm 48, a movable contact 48s that is displaced in the axial direction in accordance with the deformation of the diaphragm 48 is attached. The fixed contact 47k is attached to the position of the movable contact 48s on the movement extension line, that is, the inner wall surface of the other room (lower room) in the housing 47.

Therefore, when the fuel pressure applied to the diaphragm 48 via the pressure introduction port 47p of the first switch 45 exceeds a predetermined pressure Lo, the movable contact 48s contacts the fixed contact 47k as the diaphragm 48 is deformed, and the first switch 45 conducts (turns on).
In the case of the second switch 46, when the fuel pressure applied to the diaphragm 48 exceeds a predetermined pressure Hi, the movable contact 48s comes into contact with the fixed contact 47k with the deformation of the diaphragm 48, and the second switch 45 becomes conductive (ON). To do.
Here, FIG. 4 (B) is a graph showing the change of the fuel pressure over time, and FIG. 4 (C) shows the pressure switch 43 when the fuel pressure changes as shown in FIG. 4 (B). It is a graph showing operation | movement. When the fuel pressure (fuel pressure) increases from time t0 in FIG. 4B and the fuel pressure exceeds a predetermined pressure Lo at time t1, the first switch 45 is turned on as shown in FIG. 4C. When the fuel pressure further rises from this state and the fuel pressure exceeds a predetermined pressure Hi at time t2 as shown in FIG. 4B, the second switch 46 is turned on as shown in FIG. 4C. Next, when the fuel pressure falls from the maximum pressure and the fuel pressure falls below the predetermined pressure Hi at time t3 as shown in FIG. 4 (B), the second switch 46 is turned off as shown in FIG. 4 (C). . When the fuel pressure further decreases from this state and the fuel pressure falls below the predetermined pressure Lo at time t4 as shown in FIG. 4 (B), the first switch 45 is turned off as shown in FIG. 4 (C).

That is, as shown in FIG. 5A, when the fuel pressure P drops below a predetermined pressure Lo, for example, when P = 0 (state 1), or when 0 <P <Lo (state 2), the first Both the switch 45 and the second switch are turned off (0). Therefore, it can be seen that the fuel pressure P is lower than the predetermined pressure Lo when both the first switch 45 and the second switch are off (0). When the fuel pressure P is Lo <P <Hi (state 3), the first switch 45 is turned on (1) and the second switch 46 is turned off (0). Therefore, it can be seen that the fuel pressure P is between the predetermined pressure Lo and the predetermined pressure Hi when the first switch 45 is on (1) and the second switch 46 is off (0). Further, when the fuel pressure P is Hi <P (state 4), the first switch 45 is turned on (1) and the second switch 46 is turned on (1). Therefore, it can be seen that the fuel pressure P exceeds the predetermined pressure Hi when the first switch 45 is on (1) and the second switch 46 is on (1).
That is, the pressure switch 43 corresponds to the pressure detecting means of the present invention, the predetermined pressure Lo corresponds to the first set pressure of the present invention, and the predetermined pressure Hi corresponds to the second set pressure of the present invention.

Here, for example, when the second switch 46 breaks down or breaks down due to the inclusion of foreign matter, the second switch 46 is off (0) even if the fuel pressure P is Hi <P (state 4). It is. Therefore, if Hi <P (state 4) and the second switch 46 is off (0), it can be determined that the second switch 46 is in failure. However, when the fuel pressure P is P <Hi (states 1 to 3), the failure of the second switch 46 cannot be determined.
In order to improve this point, as shown in FIG. 5B, the first switch 45 is turned on when the fuel pressure P falls below the predetermined pressure Lo, and the second switch when the fuel pressure P falls below the predetermined pressure Hi. It is also possible to configure so that the switch 46 is turned on. Thereby, for example, when the second switch 46 is normal, the second switch 46 is turned on when the fuel pressure P is P <Hi (states 1 to 3). As a result, if the second switch 46 is off when P = 0 (state 1), it can be determined that the second switch 46 is broken or a failure is caused by a foreign object. That is, even when the fuel pressure P is P = 0, it is possible to determine the failure of the first switch 45 and the second switch 46.

The fuel pump controller FPC controls the output of the motor unit 34 of the fuel pump 30 based on the signal of the pressure switch 43, determines an abnormality from the on / off state of the pressure switch 43, the load current of the motor unit 34, etc. On the other hand, an abnormal signal or the like can be output.
As shown in the flowchart of FIG. 2, the fuel pump controller FPC is configured to be turned on when an ignition switch (IG) on signal is input from the ECU (steps S101 and S102). . When the power of the fuel pump controller FPC is turned on, the motor unit 34 of the fuel pump 30 is driven (step S103). As a result, the pump unit 32 operates and the fuel is pumped to the injector 5 through the tank external fuel supply pipe 7 and the delivery pipe 8.
Here, when the fuel pressure P is 0 <P <Lo (state 2 in FIG. 5 (A)), the first switch of the pressure switch 43 is shown at time 0 to t1 in FIGS. 3 (A) and 3 (B). 45 and the second switch 46 are both turned off (0) (see FIG. 5A). Therefore, the determination in step S105 of FIG. 2 is Lo-OFF, and the voltage applied to the motor unit 34 of the fuel pump 30, that is, the output signal of the fuel pump controller FPC is as shown in FIG. Increase by a fixed amount ΔV. Thereby, the rotation speed of the fuel pump 30 is increased (step S107 in FIG. 2). As a result, the fuel pressure P increases. Then, as shown in FIGS. 3A and 3B, when the fuel pressure P becomes Lo or more at time t1 (state 3 in FIG. 5A) due to the increase in the fuel pressure P, the first switch 45 of the pressure switch 43 is turned on. Turn on (1) (see FIG. 3B). At this time, since the second pressure switch 46 is off (0), the determination in step S105 in FIG. 2 is “maintained”, and the output signal of the fuel pump controller FPC is maintained (see FIG. 3C). .

When the fuel P rises and the fuel pressure P exceeds Hi at time t2 as shown in FIGS. 3A and 3B (state 4 in FIG. 5A), the second switch 46 of the pressure switch 43 is used. Is turned on (1) (see FIG. 3B). That is, both the first switch 45 and the second switch 46 are turned on (1). As a result, the determination in step S105 of FIG. 2 becomes Hi-ON, and the voltage applied to the motor unit 34 of the fuel pump 30, that is, the output signal of the fuel pump controller FPC is as shown in FIG. Decreases by a fixed amount ΔV. Thereby, the rotation speed of the fuel pump 30 is reduced (step S106 in FIG. 2). When the fuel pressure drops due to fuel consumption in the engine and the fuel pressure P drops below Hi at time t3 as shown in FIGS. 3A and 3B (state 3 in FIG. 5A), the pressure switch 43 The second switch 46 is turned off (0) (see FIG. 3B). That is, only the first switch 45 is turned on (1). As a result, the determination in step S105 in FIG. 2 is “maintained”, and the output signal of the fuel pump controller FPC is maintained as it is (see FIG. 3C). When the fuel pressure P further decreases and the fuel pressure P drops below Lo at time t4 as shown in FIGS. 3 (A) and 3 (B) (state 2 in FIG. 5 (A)), the first switch 45 of the pressure switch 43. Is turned off (0) (see FIG. 3B). Accordingly, the determination in step S105 in FIG. 2 is Lo-OFF, and the output signal of the fuel pump controller FPC is increased by a predetermined amount ΔV as shown in FIG.
As described above, when the fuel pressure P exceeds the predetermined pressure Hi, the fuel pump controller FPC decreases the output signal value by a certain amount ΔV with respect to the current output signal, and when the fuel pressure P decreases below the predetermined pressure Lo, the output signal value Is increased by a certain amount ΔV. For this reason, the discharge pressure of the fuel pump can be accurately controlled between the predetermined pressure Hi and the predetermined pressure Lo.
Further, the fuel pump controller FPC outputs an abnormal signal to the ECU when the load current of the motor unit 34 of the fuel pump 30 is lower than the lower limit value or higher than the upper limit value. Further, when the first switch 45 is off (0) and the second switch 46 is on (1), or the load current of the motor unit 34 is zero and the first switch 45 is on (1), the second switch 46 is An abnormal signal is also output to the ECU in the case of ON (1) or the like.
That is, the fuel pump controller FPC corresponds to the control means of the present invention.

<Advantages of the fuel pressure control system 40 according to this embodiment>
According to the fuel pressure control system 40 according to the present embodiment, for example, when the amount of fuel injected from the injector 5 decreases when the engine (vehicle) decelerates and the fuel pressure P exceeds a predetermined pressure Hi, the fuel pump controller FPC. Decreases the output of the motor part 34 of the fuel pump 30 by a certain amount. As a result, the fuel pressure P gradually decreases. Further, when the amount of fuel injected from the injector 5 increases during acceleration of the engine (vehicle) and the fuel pressure P falls below the predetermined pressure Lo, the fuel pump controller FPC keeps the output of the motor unit 34 of the fuel pump 30 constant. Increase the amount. As a result, the fuel pressure P gradually increases. Further, when the amount of fuel injected from the injector 5 is substantially constant when the engine (vehicle) is operated at a constant speed and the fuel pressure P is between the predetermined pressure Lo and the predetermined pressure Hi, the fuel pump controller FPC The output of the motor unit 34 is maintained as it is.
As described above, when the discharge pressure (fuel pressure P) of the fuel pump 30 exceeds the predetermined pressure Hi, the fuel pump controller FPC decreases the output signal value by a certain amount ΔV with respect to the current output signal, and the fuel pressure P is predetermined. When the pressure drops below the pressure Lo, the output signal value is increased by a certain amount ΔV. For this reason, the fuel pressure P can be accurately controlled between the predetermined pressure Lo and the predetermined pressure Hi.
The pressure detection means (pressure switch 43) only needs to be able to detect whether the fuel pressure P is between the predetermined pressure Lo and the predetermined pressure Hi, exceeds the predetermined pressure Hi, or lower than the predetermined pressure Lo. Compared with the continuous detection method, the pressure detection means can be simplified and the cost can be reduced. Further, since the fuel pump controller FPC is configured to increase or decrease the output signal value by a certain amount relative to the current output signal, the fuel pump controller FPC is compared with a method in which the output signal is continuously changed. Can be simplified and the cost can be reduced.
Further, if the operations of the first switch 45 and the second switch 46 of the pressure switch 43 are reversed, the first switch 45 and the second switch 46 are turned on when the fuel pressure before operation is zero. become. For this reason, by confirming the conduction state of the first switch 45 and the second switch 46 before the operation, it is possible to find a failure state such as disconnection or biting of foreign matter.

<Example of change>
The present invention is not limited to the above-described embodiment, and modifications can be made without departing from the gist of the present invention.
In the fuel pressure control system 40 according to the present embodiment, the example in which the fuel pressure P is controlled in the range of the predetermined pressure Lo to the predetermined pressure Hi by the pressure switch 43 including the first switch 45 and the second switch 46 has been shown. However, as shown in FIGS. 7 and 8, it is also possible to provide two sets of pressure switches 43 having different pressure ranges and control the fuel pressure P in two stages, the high pressure side and the low pressure side.
That is, the fuel pressure control system 40 shown in FIGS. 7 and 8 includes a high pressure side pressure switch 43a and a low pressure side pressure switch 43b. In the high pressure side pressure switch 43a, the set pressure of the first switch is set to the pressure Lo2, and the set pressure of the second switch is set to the pressure Hi2. In the low pressure side pressure switch 43b, the set pressure of the first switch is set to the pressure Lo1, and the set pressure of the second switch is set to the pressure Hi1. Further, the fuel pump controller FPC is provided with a selection means (see FIG. 8, step S103 to step S105) for selecting either the signal of the high pressure side pressure switch 43a or the signal of the low pressure side pressure switch 43b. . Further, a signal from a water temperature sensor 39 that measures the coolant temperature of the engine is input to the fuel pump controller FPC.

For this reason, for example, when it is detected by the signal from the water temperature sensor 39 that the water temperature has reached the fuel vapor generation temperature, the selection means selects the signal of the high pressure side pressure switch 43a in order to set the fuel pressure P to the high pressure P2. FIG. 8 Step S105 P2). Accordingly, the fuel pump controller FPC controls the fuel pressure P between the predetermined pressure Lo2 and the predetermined pressure Hi2 based on the signal from the high pressure side pressure switch 43a (step S111 in FIG. 8). Further, in a state where the water temperature does not reach the fuel vapor generation temperature, the selection means selects the signal of the low pressure side pressure switch 43b in order to set the fuel pressure P to the low pressure P1 (step S105 P1 in FIG. 8). Accordingly, the fuel pump controller FPC controls the fuel pressure P between the predetermined pressure Lo1 and the predetermined pressure Hi1 based on the signal from the low pressure side pressure switch 43b (step S112 in FIG. 8).
Here, immediately after the fuel pressure P is switched from the low pressure P1 to the high pressure P2, the fuel pump controller FPC quickly raises the fuel pressure P. Therefore, the signal increase ΔV with respect to the current output signal is set to a larger value than usual. . Immediately after the fuel pressure P is switched from the high pressure P2 to the low pressure P1, the signal decrease ΔV with respect to the current output signal is set to a larger value than usual in order to quickly reduce the fuel pressure P. Thereby, the fuel pressure P can be quickly switched between the low pressure P1 and the high pressure P2.

Moreover, in this embodiment, as shown in FIG. 4, the example which uses the double switch which consists of the 1st switch 45 and the 2nd switch 46 as the pressure switch 43 was shown. However, for example, the pressure switch 50 shown in FIG. 6 can be used. The pressure switch 50 includes a movable contact 48 s provided at the center of the diaphragm 48, and a low-pressure side fixed contact 49 and a high-pressure side fixed contact 47 k provided on the housing 47. Then, as shown in FIGS. 6B and 6C, when the fuel pressure P is lower than the predetermined pressure Lo (P <Lo), the movable contact 48s and the low-pressure side fixed contact 49 are electrically connected. Further, when the fuel pressure P exceeds the predetermined pressure Lo and is lower than the predetermined pressure Hi (Lo <P <Hi), the movable contact 48s is in a neutral state. Further, when the fuel pressure P exceeds the predetermined pressure Hi (Hi <P), the movable contact 48s and the low-pressure side fixed contact 49 are brought into conduction.
By using the pressure switch 50, it is possible to reduce the size and cost of the switch.
In this embodiment, the diaphragm type pressure switch is exemplified, but the configuration of the pressure switch can be changed as appropriate.

It is the schematic of the fuel pressure control system which concerns on Embodiment 1 of this invention. It is a flowchart showing operation | movement of a fuel pressure control system. It is a graph (A figure, B figure, C figure) showing each part operation | movement of a fuel pressure control system. It is the model (A figure) showing the pressure switch in a fuel pressure control system, the change figure (B figure) of a fuel pressure, and the operation | movement figure (C figure) of a pressure switch. It is the operation | movement table | surface (FIG. A) of a pressure switch, and the operation | movement table | surface (B figure) at the time of operation reversal of a pressure switch. It is the model (A figure) showing the pressure switch which concerns on the example of a change, the change figure (B figure) of a fuel pressure, and the operation | movement figure (C figure) of a pressure switch. It is the schematic of the fuel pressure control system which concerns on the example of a change. It is a flowchart showing operation | movement of the fuel pressure control system which concerns on the example of a change.

Explanation of symbols

5. Injector 10 ... Fuel supply device 30 ... Fuel pump 34 ... Motor unit (motor for fuel pump)
39 ... Water temperature sensor 40 ... Fuel pressure control system 43 ... Pressure switch (pressure detection means)
45... First switch 46... Second switch FPC .. Fuel pump controller (control means)
Lo ··· Predetermined pressure (first set pressure)
Hi ... Predetermined pressure (second set pressure)

Claims (3)

In a fuel pressure control system that controls fuel pressure by changing the output of a fuel pump that pumps fuel,
Pressure detecting means capable of detecting whether the fuel pressure is between the first set pressure and the second set pressure, exceeds the second set pressure, or falls below the first set pressure;
When the fuel detection signal is received and the fuel pressure exceeds a second set pressure, the output of the motor for the fuel pump is reduced by a certain amount, and when the fuel pressure is lower than the first set pressure, the motor Control means for maintaining a current output of the motor when the fuel pressure is between a first set pressure and a second set pressure,
A selection means for selecting any one of the plurality of pressure detection means having different set pressure ranges;
The control means controls the output of the motor based on a signal from the pressure detection means selected by the selection means . The fuel pressure control system according to claim 1,
The pressure detecting means includes a first switch and a second switch,
A fuel pressure, wherein the first switch is conductive when the fuel pressure is lower than a first set pressure, and the second switch is conductive when the fuel pressure is lower than a second set pressure. Control system. In a fuel pressure control system that controls fuel pressure by changing the output of a fuel pump that pumps fuel,
Pressure detecting means capable of detecting whether the fuel pressure is between the first set pressure and the second set pressure, exceeds the second set pressure, or falls below the first set pressure;
When the fuel detection signal is received and the fuel pressure exceeds a second set pressure, the output of the motor for the fuel pump is reduced by a certain amount, and when the fuel pressure is lower than the first set pressure, the motor And a control means for maintaining the current output of the motor when the fuel pressure is between a first set pressure and a second set pressure.
The pressure detecting means includes a first switch and a second switch,
A fuel pressure, wherein the first switch is conductive when the fuel pressure is lower than a first set pressure, and the second switch is conductive when the fuel pressure is lower than a second set pressure. Control system.

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