JP3481858B2 - Accumulator type fuel injection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-accumulation fuel injection device having a common rail (accumulation pipe) used in, for example, a diesel engine.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram showing a conventional pressure-accumulation type fuel injection device. In FIG. 7, an engine (internal combustion engine) 1
Is provided with an injector 2 for the combustion chamber of each cylinder, and fuel injection from the injector 2 to the engine 1 is
It is controlled by turning on and off the injection control solenoid valve 3.
The injector 2 is connected to a common rail 4, which is a high-pressure accumulator pipe common to each cylinder, and while the injection control solenoid valve 3 is open, the fuel in the common rail 4 is injected into the injector 2.
Is injected into each cylinder of the engine 1. The high-pressure supply pump 7 includes a plunger 31 reciprocatingly and slidably mounted in a cylinder 30.
Of the pump chamber 32 by the upper end surface of the cylinder and the inner peripheral surface of the cylinder 30.
Is configured. The cam follower 35 is fixed to the cam shaft that rotates in synchronization with the rotation of the engine and is disposed in the cam chamber 34. Also, the plunger 31
Is urged by the plunger spring 33 to come into contact with the cam follower 35. In addition, the discharge amount control valve 1
1 is provided in the passage for supplying the low pressure fuel to the pump chamber 32, and the low pressure fuel can be supplied to the pump chamber 32 when the valve is opened. In the high-pressure supply pump 7, the cam follower 35 is rotated by the cam shaft in synchronization with the rotation of the engine, and the plunger 31 reciprocates in the cylinder 30. Due to the reciprocating movement of the plunger 31, the fuel sucked from the fuel tank 8 into the pump chamber 32 through the low pressure supply pump 9 is boosted, and the boosted fuel is sent to the common rail 4 through the supply pipe 5. Here, the common rail 4 is connected to a high-pressure supply pump 7 via a supply pipe 5 and a check valve 6 so that a high predetermined pressure corresponding to the fuel injection pressure is continuously accumulated in the common rail 4. Further, the pressure control valve 10 is arranged in a pipe branched from the discharge side pipe of the low pressure supply pump 9, and when the pressure of the fuel supplied to the high pressure supply pump 7 by the low pressure supply pump 9 exceeds a predetermined pressure. The fuel is returned to the fuel tank 8 via the pressure control valve 10, and an excessive increase in the pressure of the fuel supplied to the high pressure supply pump 7 is suppressed.

The electronic control unit (ECU) 12 receives information on the number of revolutions, the load and the cylinders from an engine revolution sensor 13, a load sensor 14 and a cylinder discrimination sensor 15. The ECU 12 controls the injection control solenoid valve 3 corresponding to each cylinder so that the optimum injection timing and injection amount (injection time) are determined according to the engine state determined by the signals of the rotation speed and the load. Output a signal. At the same time, the ECU 12 outputs a control signal to the discharge amount control valve 11 so that the injection pressure has an optimum value according to the rotation speed and the load. Furthermore, a pressure sensor 1 for detecting the common rail pressure
6 is arranged on the common rail 4, and the discharge amount is controlled so that the signal of the pressure sensor 16 becomes an optimum value set in advance according to the load and the number of revolutions (pressure negative feedback control), and the common rail pressure is precisely controlled. To be done. Further, when the safety valve 70 is arranged in the fuel return pipe 36 of the common rail 4 and the common rail pressure becomes excessive, the fuel is returned to the fuel tank 8 through the safety valve 70 and the fuel return pipe 36, and the common rail pressure becomes excessive. The rise is controlled.

Here, if the sliding failure or seizure of the plunger 31 occurs, the valve body of the discharge amount control valve 11 is stuck in the seat state, or the electromagnetic coil or the wiring is broken, the high pressure supply pump 7 is generated. The non-pressurized state of occurs. When the high-pressure supply pump 7 is in a non-pressure-feeding state, the fuel pressure in the common rail 4 sharply drops, and when the fuel pressure drops below the operable minimum injection pressure (about 12 MPa) of the engine 1, the vehicle suddenly stops during operation. The worst is the problem of human life. In the conventional pressure accumulation type fuel injection device, the ECU 1
2 is the pressure sensor 1 when the pressure drop in the common rail 4
By making a determination from the signal of No. 6 and issuing a warning to the driver, the occurrence of the non-pressure feeding state of the high-pressure supply pump 7 is dealt with.

[0005]

As described above, the conventional pressure-accumulation type fuel injection device has no safety device for the high-pressure supply pump 7 in the non-pressure-feeding state. That is, the ECU 12 determines the pressure drop in the common rail 4 from the signal of the pressure sensor 16 and issues a warning to the driver, so that the high pressure supply pump 7
Therefore, if the driver continues to drive the vehicle while searching for a safe place after receiving the warning, the fuel pressure in the common rail 4 suddenly drops,
There has been a problem that the vehicle may be stopped suddenly due to a drop below the operable minimum injection pressure of the engine 1, causing an accident.

The present invention has been made to solve the above problems, and even if the high-pressure supply pump is in a non-pressurized state, the vehicle can be safely driven for a predetermined time without sudden stop, and An object of the present invention is to obtain a pressure accumulating fuel injection device in which safety measures for a pumping state are secured.

[0007]

SUMMARY OF THE INVENTION A pressure-accumulation fuel injection system according to the present invention has a common rail for accumulating pressurized fuel, an injector for injecting the fuel in the common rail to each cylinder of an internal combustion engine, and a fuel flow. It has a pump chamber, and pumps the fuel in the pump chamber toward the common rail,
A high-pressure supply pump for pressurizing the fuel in the common rail,
A low-pressure supply pump that is disposed in a path of a low-pressure fuel supply pipe that connects the pump chamber and the fuel tank, and pumps up the fuel in the fuel tank to supply the fuel to the pump chamber; and the pump chamber and the low-pressure fuel. A discharge amount control valve that is provided in a passage that communicates with the supply pipe and that communicates the pump chamber and the low-pressure fuel supply pipe when the valve is opened, and the discharge amount control valve is opened / closed to control the fuel pressure in the common rail. In a pressure accumulation type fuel injection device having an electronic control unit for controlling to a predetermined pressure, a low pressure fuel return pipe branched from the low pressure fuel supply pipe downstream of the low pressure supply pump to reach the fuel tank. A first control pressure arranged in the path of the low-pressure fuel return pipe for setting the fuel pressure in the low-pressure fuel supply pipe to a first control pressure lower than the minimum injection pressure of the common rail. A force control valve, a bypass pipe that is branched from the upstream side of the first pressure control valve of the low-pressure fuel return pipe to reach the fuel tank, and is disposed in the path of the bypass pipe, A second pressure control valve that sets the pressure of the fuel in the low-pressure fuel supply pipe to a second control pressure that is higher than the lowest injection pressure of the common rail, and the low-pressure fuel supply when the high-pressure supply pump sends no pressure. And a valve switching means for switching the setting of the pressure in the pipe from the first pressure control valve to the second pressure control valve.

Further, the valve switching means is arranged downstream of the first pressure control valve in the low-pressure fuel return pipe, and the normal discharge amount of the high-pressure supply pump becomes the normal overflow amount. It is composed of a flow rate control valve that operates so as to block the flow of fuel through the low-pressure fuel return pipe when added.

Further, the valve switching means is constituted by an electromagnetic switching valve disposed upstream of the first pressure control valve in the low pressure fuel return pipe, and the electromagnetic switching valve is a pressure control valve in the common rail. Is controlled to be opened and closed by the electronic control unit so that the flow of fuel through the low pressure fuel return pipe is interrupted when the pressure becomes lower than the minimum injection pressure.

Further, a common rail for accumulating the pressurized fuel, an injector for injecting the fuel in the common rail into each cylinder of the internal combustion engine, and a pump chamber into which the fuel flows are provided, and the fuel in the pump chamber is stored in the common rail. A high-pressure supply pump that pumps the fuel in the common rail and pressurizes the fuel in the common rail, and a low-pressure fuel supply pipe that connects the pump chamber and the fuel tank are arranged in a path to pump up the fuel in the fuel tank. A low-pressure supply pump that supplies the pump chamber, a discharge amount control valve that is provided in a passage that communicates the pump chamber and the low-pressure fuel supply pipe, and that communicates the pump chamber and the low-pressure fuel supply pipe when the valve is opened. A low-pressure accumulator type fuel injection device having an electronic control unit for controlling the opening / closing of the discharge amount control valve to control the fuel pressure in the common rail to a predetermined pressure. Inside the low-pressure fuel supply pipe, which is arranged in the path of the low-pressure fuel return pipe branched from the downstream side of the low-pressure supply pump of the fuel supply pipe to reach the fuel tank. Fuel pressure is lower than the minimum injection pressure of the common rail above
Control pressure or a second control pressure that is higher than the lowest injection pressure of the common rail, and the electromagnetic pressure control valve is configured such that the pressure in the common rail becomes lower than the lowest injection pressure. At this time, the electromagnetic control unit controls so that the pressure of the fuel in the low pressure fuel supply pipe is set to the second control pressure.

A fuel passage is provided so as to connect the upstream side of the first pressure control valve of the bypass pipe and the common rail, and the pressure in the common rail is higher than the first control pressure. In addition, a check valve that operates when the pressure becomes lower than the minimum injection pressure is arranged in the path of the fuel passage.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1. 1 is a configuration diagram showing a pressure accumulation type fuel injection device according to Embodiment 1 of the present invention, and in FIG.
The same or corresponding parts as those of the conventional pressure-accumulation type fuel injection device shown in FIG.

In FIG. 1, the low pressure fuel supply pipe 40 is
The low pressure supply pump 9 is connected from the fuel tank 8 to the pump chamber 32 of the high pressure supply pump 7, and is arranged in the path of the low pressure fuel supply pipe 40. Also, the low pressure fuel return pipe 41
However, on the downstream side of the low pressure supply pump 9, the low pressure fuel supply pipe 40
It is branched so as to reach the fuel tank 8. The first pressure control valve 80 is disposed in the path of the low pressure fuel return pipe 41, and the flow rate control valve 82 is
First pressure control valve 80 in the path of low pressure fuel return line 41
Is disposed on the downstream side of the. In addition, the bypass pipe 42
Is arranged so that the upstream side of the first pressure control valve 80 of the low pressure fuel return pipe 41 and the downstream side of the flow rate control valve 82 communicate with each other, and the second pressure control valve 81 connects the route of the bypass pipe 42. It is arranged inside. Here, the first pressure control valve 80
Is for setting the pressure of the fuel supplied from the low pressure supply pump 9 to the high pressure supply pump 7 under normal conditions, and the first control pressure P ₁ thereof is set to a pressure lower than the minimum injection pressure (about 12 MPa). . Further, the second pressure control valve 81 is
The pressure of the fuel supplied from the low pressure supply pump 9 to the high pressure supply pump 7 is set by operating during non-pressure feeding, and the second control pressure P ₂ thereof is set to a pressure equal to or higher than the minimum injection pressure. Further, the flow rate control valve 82 is a high pressure supply pump 7.
During non-pressure feeding, the normal discharge amount of the high-pressure supply pump 7 is added to the normal overflow amount to operate, and is supplied from the low-pressure supply pump 9 to the high-pressure supply pump 7 during non-pressure feeding. A valve switching unit that switches the setting of the fuel pressure from the first pressure control valve 80 in the normal state to the second pressure control valve 81 is configured. The other configuration is shown in FIG.
It is configured similarly to the conventional pressure-accumulation fuel injection device shown in FIG.

Next, the operation of the pressure accumulation type fuel injection device according to the first embodiment will be described. High pressure supply pump 7
During normal operation, the fuel in the fuel tank 8 is supplied by the low pressure supply pump 9
High-pressure supply pump 7 via low-pressure fuel supply pipe 40
Is supplied to. When the pressure of the fuel in the low pressure fuel supply pipe 40 exceeds the first control pressure P ₁ , the first pressure control valve 80 opens and the fuel is returned to the fuel tank 8 via the low pressure fuel return pipe 41. Therefore, the pressure of the fuel in the low pressure fuel supply pipe 40 is maintained (set) at the first control pressure P ₁ . Then, the plunger 31 descends and the discharge amount control valve 1
1 is opened, and the fuel set to the first control pressure P ₁ is supplied to the pump chamber 32 of the high-pressure supply pump 7. Then, the discharge amount control valve 11 is closed, the plunger 31 is raised, the fuel in the pump chamber 32 is pressurized, and the boosted fuel is supplied to the common rail 4 via the check valve 6 and the supply pipe 5. By repeating this operation, a high predetermined pressure corresponding to the fuel injection pressure is continuously accumulated in the common rail 4.

When the sliding failure or seizure of the plunger 31 occurs, the high pressure supply pump 7 is in a non-pressure feeding state. In this non-pressure-feeding state, since the plunger 31 is not moving up and down, the pressure in the pump chamber 32 is controlled by the discharge amount control valve 1.
When the valve 1 is opened, the pressure becomes the same as the fuel pressure in the low pressure fuel supply pipe 40. Since the pressure in the pump chamber 32 is lower than the operating pressure of the check valve 6, the check valve 6 does not operate, the high-pressure fuel is not supplied to the common rail 4, and the pressure in the common rail 4 drops. .

When this non-pressurized feed state occurs, the high-pressure supply pump 7 does not discharge the fuel. Therefore, the fuel returned to the fuel tank 8 through the low-pressure fuel return pipe 41 is discharged when the high-pressure supply pump 7 is operating normally. The amount is added to the overflow amount at the normal time. Therefore, the flow rate control valve 82 is operated and closed, and the fuel is not returned to the fuel tank 8 through the low pressure fuel return pipe 41. That is, the setting of the fuel pressure supplied from the low pressure supply pump 9 to the high pressure supply pump 7 is switched from the first pressure control valve 80 to the second pressure control valve 81. Therefore, when the pressure in the low-pressure fuel supply pipe 40 rises due to the operation of the low-pressure supply pump 9 and reaches the second control pressure P ₂ , the second pressure control valve 81 opens, and the fuel passes through the bypass pipe 42. It is returned to the fuel tank 8. As a result, the pressure in the low pressure fuel supply pipe 40 is maintained at the _second control pressure P ₂ . Then, by opening the discharge amount control valve 11,
The high-pressure fuel maintained at the second control pressure P ₂ is supplied into the pump chamber 32. Since the second control pressure P ₂ is higher than the operating pressure of the check valve 6, the discharge amount control valve 1
By opening and closing 1, the high-pressure fuel maintained at the second control pressure P ₂ is supplied into the common rail 4, and the pressure drop in the common rail 4 due to the non-pressurized state of the high-pressure supply pump 7 is suppressed.

When the discharge control valve 11 is opened due to disconnection of the electromagnetic coil, disconnection of wiring, etc., the fuel in the pump chamber 32 is returned to the low-pressure fuel supply pipe 40 side in the process of raising the plunger 31. , Fuel pressure is not increased. Therefore, since the fuel in the pump chamber 32 is not boosted in pressure, the check valve 6 does not operate, the high-pressure supply pump 7 is in a non-pressurized state, and the high-pressure fuel is not supplied to the common rail 4, so that the common rail 4 is not supplied. Pressure drop occurs.

When this non-pressurized feed state occurs, the high-pressure supply pump 7 does not discharge the fuel. Therefore, the fuel returned to the fuel tank 8 through the low-pressure fuel return pipe 41 is discharged when the high-pressure supply pump 7 is operating normally. The amount is added to the overflow amount at the normal time. Therefore, the flow rate control valve 82 is operated and closed, and the fuel is not returned to the fuel tank 8 through the low pressure fuel return pipe 41. That is, the setting of the fuel pressure supplied from the low pressure supply pump 9 to the high pressure supply pump 7 is switched from the first pressure control valve 80 to the second pressure control valve 81. Therefore, when the pressure in the low-pressure fuel supply pipe 40 rises due to the operation of the low-pressure supply pump 9 and reaches the second control pressure P ₂ , the second pressure control valve 81 opens, and the fuel passes through the bypass pipe 42. It is returned to the fuel tank 8. As a result, the pressure in the low pressure fuel supply pipe 40 is maintained at the _second control pressure P ₂ . Then, the high-pressure fuel maintained at the second control pressure P ₂ is supplied into the pump chamber 32. Since the second control pressure P ₂ is higher than the operating pressure of the check valve 6, the high-pressure fuel maintained at the _second control pressure P ₂ is supplied into the common rail 4 via the check valve 6 and the supply pipe 5. As a result, the pressure drop in the common rail 4 due to the non-pressurized state of the high-pressure supply pump 7 is suppressed. Therefore, the pressure in the common rail 4 is maintained at a pressure higher than the minimum injection pressure, and sudden stop of the vehicle is prevented.

As described above, according to the first embodiment,
The low-pressure fuel return pipe 41 and the bypass pipe 42 are piped so as to branch from the low-pressure fuel supply pipe 40 downstream of the low-pressure supply pump 9 to reach the fuel tank 8, and have a first control pressure P lower than the minimum injection pressure. _{The first} first pressure control valve 80 is disposed in the low pressure fuel return pipe 41, and the second pressure control valve 81 having a _second control pressure P _{2 that} is higher than the minimum injection pressure is disposed in the bypass pipe 42. Further, a flow rate control valve 82 that operates when the normal discharge amount of the high pressure supply pump 7 is added to the normal overflow amount is disposed in the low pressure fuel return pipe 41 downstream of the first pressure control valve 80. Has been done. Therefore, when the high pressure supply pump 7 is pressurelessly fed, the low pressure supply pump 9
The setting of the fuel pressure supplied from the high pressure supply pump 7 to the high pressure supply pump 7 is switched by the flow rate control valve 82 from the first pressure control valve 80 to the second pressure control valve 81. Since the pressure drop in 4 is suppressed, even if the high-pressure supply pump 7 is in a non-pressurized state, the pressure in the common rail 4 is drastically reduced to prevent the vehicle from abruptly stopping. The vehicle can be safely driven for a predetermined time without doing so.

Embodiment 2. In the second embodiment, as shown in FIG. 2, the valve switching means is configured in the same manner as in the first embodiment except that an electromagnetic switching valve 83 is used instead of the flow rate control valve 82. ing. In addition,
The electromagnetic switching valve 83 is provided on the upstream side of the first pressure control valve 80 in the low pressure fuel return pipe 41, and is opened / closed by the ECU 12 based on the pressure in the common rail 4.

Next, the operation of the pressure accumulating fuel injection device according to the second embodiment will be described. The ECU 12 inputs the detection signal of the pressure sensor 16 and monitors the pressure in the common rail 4. When the pressure in the common rail 4 is equal to or higher than the minimum injection pressure, the ECU 12 determines that the operation is normal and opens the electromagnetic switching valve 83 to set the fuel pressure supplied from the low pressure supply pump 9 to the high pressure supply pump 7. The first
The pressure control valve 80 of FIG. On the other hand, when the pressure in the common rail 4 becomes lower than the minimum injection pressure, the ECU 12 determines that an abnormality has occurred and closes the electromagnetic switching valve 83 to close the fuel pressure supplied from the low pressure supply pump 9 to the high pressure supply pump 7. The setting is switched from the first pressure control valve 80 to the second pressure control valve 81.

Therefore, if the ECU 12 determines that the operation is normal, the fuel in the fuel tank 8 is supplied from the low pressure supply pump 9 to the high pressure supply pump 7 through the low pressure fuel supply pipe 40. Further, the pressure of the fuel in the low-pressure fuel supply pipe 40 is the first
When the control pressure P ₁ of the fuel tank 8 exceeds the control pressure P ₁ , the first pressure control valve 80 opens and the fuel flows through the low pressure fuel return pipe 41 to the fuel tank
As a result, the fuel pressure in the low-pressure fuel supply pipe 40 is maintained and set at the _first control pressure P ₁ . Therefore, the plunger 31 is lowered, the discharge amount control valve 11 is opened, and the fuel set to the _first control pressure P ₁ is supplied with the high pressure supply pump 7.
Is supplied to the pump chamber 32. Next, the discharge control valve 1
1 is closed, the plunger 31 is raised and the pump chamber 32
The fuel inside is boosted, and the boosted fuel is supplied to the common rail 4 via the check valve 6 and the supply pipe 5. By repeating this operation, a high predetermined pressure corresponding to the fuel injection pressure is continuously accumulated in the common rail 4.

Here, the displacement control valve 11 is opened due to the sliding failure or seizure of the plunger 31 or the disconnection of the electromagnetic coil or the disconnection of the wiring. Then, the high-pressure fuel is not supplied to the common rail 4, and the pressure in the common rail 4 drops. Therefore, the ECU 12 determines that an abnormality has occurred, closes the electromagnetic switching valve 83, and the fuel pressure supplied from the low pressure supply pump 9 to the high pressure supply pump 7 is set from the first pressure control valve 80 to the second pressure. It is switched to the control valve 81. Then, the pressure of the fuel in the low-pressure fuel supply pipe 40 is maintained at the _second control pressure P ₂ by the second pressure control valve 81. The fuel set to the _second control pressure P ₂ by the second pressure control valve 81 is supplied to the common rail 4 via the high pressure supply pump 7, and the pressure in the common rail 4 is maintained higher than the minimum injection pressure. It

Therefore, also in the second embodiment, the same effect as in the first embodiment can be obtained. Further, according to the second embodiment, since the ECU 12 controls the switching by the electromagnetic switching valve 83, the setting of the fuel pressure supplied from the low pressure supply pump 9 to the high pressure supply pump 7 at the start of the internal combustion engine is performed first. It is possible to switch to the second pressure control valve 81. Therefore, when the internal combustion engine is started, high-pressure fuel is sent to the common rail 4 via the high-pressure supply pump 7, and the pressure in the common rail 4 can be quickly raised.

Embodiment 3. In the third embodiment, as shown in FIG. 3, the low-pressure fuel return pipe 41 branches from the low-pressure fuel supply pipe 40 downstream of the low-pressure supply pump 9,
The electromagnetic pressure control valve 8 is piped to reach the fuel tank 8.
4 is provided in the path of the low pressure fuel return pipe 41.
The electromagnetic pressure control valve 84 is pressure-controlled by the ECU 12 so that the fuel pressure normally supplied from the low-pressure supply pump 9 to the high-pressure supply pump 7 becomes the first control pressure P _1, and the pressure in the common rail 4 is controlled. Is lower than the minimum injection pressure, the fuel pressure supplied from the low pressure supply pump 9 to the high pressure supply pump 7 is controlled to the second control pressure P ₂ .

Next, the operation of the pressure accumulation type fuel injection device according to the third embodiment will be described. The ECU 12 inputs the detection signal of the pressure sensor 16 and monitors the pressure in the common rail 4. Then, when the pressure in the common rail 4 becomes lower than the minimum injection pressure, the ECU 12 determines that an abnormality has occurred. Therefore, when the ECU 12 is operating normally,
The electromagnetic pressure control valve 84 is controlled so that the fuel pressure supplied from the low-pressure supply pump 9 to the high-pressure supply pump 7 becomes the first control pressure P _1, and when the abnormality occurs, the low-pressure supply pump 9 supplies the high-pressure supply pump 7 to the high-pressure supply pump 7. The electromagnetic pressure control valve 84 is controlled so that the fuel pressure to be controlled becomes the second control pressure P ₂ .

Therefore, when the ECU 12 determines that the operation is normal, the fuel in the fuel tank 8 is supplied to the high pressure supply pump 7 by the low pressure supply pump 9 through the low pressure fuel supply pipe 40. Further, the pressure of the fuel in the low-pressure fuel supply pipe 40 is the first
When the control pressure P ₁ of the fuel tank 8 exceeds the control pressure P ₁ , the first pressure control valve 80 opens and the fuel flows through the low pressure fuel return pipe 41 to the fuel tank
As a result, the fuel pressure in the low-pressure fuel supply pipe 40 is maintained and set at the _first control pressure P ₁ . Therefore, the plunger 31 is lowered, the discharge amount control valve 11 is opened, and the fuel set to the _first control pressure P ₁ is supplied with the high pressure supply pump 7.
Is supplied to the pump chamber 32. Next, the discharge control valve 1
1 is closed, the plunger 31 is raised and the pump chamber 32
The fuel inside is boosted, and the boosted fuel is supplied to the common rail 4 via the check valve 6 and the supply pipe 5. By repeating this operation, a high predetermined pressure corresponding to the fuel injection pressure is continuously accumulated in the common rail 4.

Here, the displacement control valve 11 is opened due to defective sliding of the plunger 31, seizure, disconnection of the electromagnetic coil, disconnection of wiring, etc., and the high-pressure supply pump 7 is in a non-pressure-feeding state. Then, the high-pressure fuel is not supplied to the common rail 4, and the pressure in the common rail 4 drops. Therefore, the ECU 12 determines that an abnormality has occurred, and controls the electromagnetic pressure control valve 84 so that the fuel pressure supplied from the low pressure supply pump 9 to the high pressure supply pump 7 becomes the second control pressure P ₂ . The fuel set to the second control pressure P ₂ passes through the high pressure supply pump 7 and the common rail 4
And the pressure in the common rail 4 is maintained higher than the minimum injection pressure.

Further, when the internal combustion engine is started, the ECU 12 can control the electromagnetic pressure control valve 84 so that the fuel pressure supplied from the low pressure supply pump 9 to the high pressure supply pump 7 becomes the second control pressure P ₂ . Therefore, high-pressure fuel is sent to the common rail 4 via the high-pressure supply pump 7, and the pressure in the common rail 4 can be quickly raised.

Therefore, also in the third embodiment, the same effect as in the second embodiment can be obtained.

Fourth Embodiment In the fourth embodiment, as shown in FIG. 4, the fuel passage 43 is connected to the bypass pipe 42.
Of the second pressure control valve 81, is branched from the upstream side of the second pressure control valve 81 to reach the common rail 4, and the check valve 85 is connected to the fuel passage 4.
It is arranged in the route of 3. The operating pressure of the check valve 85 is set to be higher than the first control pressure P ₁ and lower than the minimum injection pressure, and the check valve 85 determines that the pressure in the common rail 4 is lower than the operating pressure. When that happens, the valve opens,
The fuel in the low-pressure fuel supply pipe 40 is supplied into the common rail 4. The rest of the configuration is similar to that of the first embodiment.

Next, the operation of the pressure accumulation type fuel injection device according to the fourth embodiment will be described. High pressure supply pump 7
At the normal time of, the control pressure P is the same as in the first embodiment.
_After the fuel set to ₁ is supplied from the low pressure supply pump 9 to the high pressure supply pump 7 and the pressure is increased by the high pressure supply pump 7,
It is supplied to the common rail 4 via the check valve 6 and the supply pipe 5. As a result, a high predetermined pressure corresponding to the fuel injection pressure is continuously accumulated in the common rail 4. At this time, from the common rail 4 to the fuel passage 4
The check valve 85 prevents the backflow of the fuel to the fuel cell 3.

Further, when the displacement control valve 11 is opened due to the sliding failure or seizure of the plunger 31 or the disconnection of the electromagnetic coil or the disconnection of the wiring, the high pressure supply pump 7 is in the non-pressure feeding state. . In the non-pressure-feeding state of the high-pressure supply pump 7, the fuel pressure supplied from the low-pressure supply pump 9 to the high-pressure supply pump 7 is set from the first pressure control valve 80 to the second pressure as in the first embodiment. It is switched to the control valve 81. Then, the pressure of the fuel in the low-pressure fuel supply pipe 40 is adjusted to the second control pressure P by the second pressure control valve 81.
Maintained at ₂ . This second pressure control valve 81
The fuel set to the control pressure P ₂ is supplied to the common rail 4 via the high pressure supply pump 7, and the pressure in the common rail 4 is maintained higher than the minimum injection pressure. At this time,
If the pressure in the common rail 4 is lower than the operating pressure of the check valve 85, the check valve 85 operates, high-pressure fuel is also sent from the fuel passage 43 into the common rail 4, and the pressure in the common rail 4 is increased. Is maintained above the minimum injection pressure.

Further, when the valve body of the discharge amount control valve 11 is stuck in the seat state, the fuel is not supplied from the low pressure supply pump 9 to the high pressure supply pump 7, so that the high pressure supply pump 7 is in a non-pressure feeding state. Even in this non-pressurized state, the high-pressure fuel is not supplied to the common rail 4, and the pressure in the common rail 4 drops.

When the non-pressurized state of this mode occurs, the high-pressure supply pump 7 does not discharge the fuel, so the fuel returned to the fuel tank 8 via the low-pressure fuel return pipe 41 is
The normal discharge amount of the high-pressure supply pump 7 is added to the normal overflow amount. Therefore, the flow rate control valve 82 is operated and closed, and the fuel is not returned to the fuel tank 8 through the low pressure fuel return pipe 41. Therefore, when the pressure in the low-pressure fuel supply pipe 40 rises due to the operation of the low-pressure supply pump 9 to reach the second control pressure P ₂ , the second pressure control valve 81
Is opened, and the fuel is returned to the fuel tank 8 through the bypass pipe 42. As a result, the pressure in the low pressure fuel supply pipe 40 is maintained at the _second control pressure P ₂ . Then, when the pressure in the common rail 4 becomes lower than the operating pressure of the check valve 85 due to the occurrence of the non-pressurized state, the check valve 85 opens and the fuel maintained at the _second control pressure P ₂ is reached. Is supplied from the low-pressure fuel supply pipe 40 into the common rail 4 through the fuel passage 43, and the pressure in the common rail 4 is maintained higher than the minimum injection pressure.

As described above, according to the fourth embodiment,
In addition to the effect of the first embodiment, the high-pressure supply pump 7 generated when the valve body of the discharge control valve 11 is stuck in the seat state
Even in the non-pressure-feeding state, the pressure in the common rail 4 is maintained higher than the minimum injection pressure, and it is possible to prevent the vehicle from suddenly stopping due to the pressure in the common rail 4 becoming lower than the minimum injection pressure. Further safety measures for the state are secured.

Embodiment 5. In the fifth embodiment, as shown in FIG. 5, the fuel passage 43 is connected to the bypass pipe 42.
Of the second pressure control valve 81, is branched from the upstream side of the second pressure control valve 81 to reach the common rail 4, and the check valve 85 is connected to the fuel passage 4.
It is arranged in the route of 3. The operating pressure of the check valve 85 is set to be higher than the first control pressure P ₁ and lower than the minimum injection pressure, and the check valve 85 determines that the pressure in the common rail 4 is lower than the operating pressure. When that happens, the valve opens,
The fuel in the low-pressure fuel supply pipe 40 is supplied into the common rail 4. The other configurations are the same as those in the second embodiment.

Next, the operation of the pressure accumulation type fuel injection device according to the fifth embodiment will be described. The ECU 12 inputs the detection signal of the pressure sensor 16 and monitors the pressure in the common rail 4. When the pressure in the common rail 4 is equal to or higher than the minimum injection pressure, the ECU 12 determines that the operation is normal and opens the electromagnetic switching valve 83 to set the fuel pressure supplied from the low pressure supply pump 9 to the high pressure supply pump 7. The first
The pressure control valve 80 of FIG. On the other hand, when the pressure in the common rail 4 becomes lower than the minimum injection pressure, the ECU 12 determines that an abnormality has occurred and closes the electromagnetic switching valve 83 to close the fuel pressure supplied from the low pressure supply pump 9 to the high pressure supply pump 7. The setting is switched from the first pressure control valve 80 to the second pressure control valve 81.

Therefore, if the ECU 12 determines that the operation is normal, the fuel set to the _first control pressure P ₁ is supplied to the pump chamber 32 of the high-pressure supply pump 7 as in the second embodiment, and the high-pressure supply is performed. The fuel that has been boosted by the pump 7 is supplied to the common rail 4 through the check valve 6 and the supply pipe 5. By repeating this operation, a high predetermined pressure corresponding to the fuel injection pressure is continuously accumulated in the common rail 4.

Further, when the displacement control valve 11 is opened due to the sliding failure of the plunger 31 or the seizure, the disconnection of the electromagnetic coil, the disconnection of the wiring, etc., the high pressure supply pump 7 is in the non-pressure feeding state. . In the non-pressure-feeding state of the high-pressure supply pump 7, the fuel pressure supplied from the low-pressure supply pump 9 to the high-pressure supply pump 7 is set from the first pressure control valve 80 to the second pressure as in the second embodiment. It is switched to the control valve 81. Then, the pressure of the fuel in the low-pressure fuel supply pipe 40 is adjusted to the second control pressure P by the second pressure control valve 81.
Maintained at ₂ . This second pressure control valve 81
The fuel set to the control pressure P ₂ is supplied to the common rail 4 via the high pressure supply pump 7, and the pressure in the common rail 4 is maintained higher than the minimum injection pressure. At this time,
If the pressure in the common rail 4 is lower than the operating pressure of the check valve 85, the check valve 85 operates, high-pressure fuel is also sent from the fuel passage 43 into the common rail 4, and the pressure in the common rail 4 is increased. Is maintained above the minimum injection pressure.

Further, if the valve body of the discharge amount control valve 11 is stuck in the seated state, the fuel is not supplied from the low pressure supply pump 9 to the high pressure supply pump 7, so that the high pressure supply pump 7 is in a non-pressure feeding state. Even in the no-pressure feeding state of this mode,
High-pressure fuel is not supplied to the common rail 4, causing a pressure drop in the common rail 4. Therefore, the ECU 1
2 determines the occurrence of an abnormality, closes the electromagnetic switching valve 83, and sets the fuel pressure supplied from the low pressure supply pump 9 to the high pressure supply pump 7 from the first pressure control valve 80 to the second pressure control valve. Switched to 81. And the low-pressure fuel supply pipe 4
The fuel pressure within 0 is maintained at the _second control pressure P ₂ by the second pressure control valve 81. Then, when the pressure in the common rail 4 becomes lower than the operating pressure of the check valve 85, the check valve 85 opens, and the fuel maintained at the _second control pressure P ₂ passes through the fuel passage 43 to the common rail 4. And the pressure in the common rail 4 is maintained higher than the minimum injection pressure.

Therefore, also in the fifth embodiment, the same effect as in the fourth embodiment can be obtained. Further, according to the fifth embodiment, since the ECU 12 controls the switching by the electromagnetic switching valve 83, the setting of the fuel pressure supplied from the low pressure supply pump 9 to the high pressure supply pump 7 at the start of the internal combustion engine is performed first. It is possible to switch to the second pressure control valve 81. Therefore, when the internal combustion engine is started, high-pressure fuel is sent to the common rail 4 via the high-pressure supply pump 7, and the pressure in the common rail 4 can be quickly raised.

Sixth Embodiment In the sixth embodiment, as shown in FIG. 6, the fuel passage 43 is connected to the bypass pipe 42.
Of the second pressure control valve 81, is branched from the upstream side of the second pressure control valve 81 to reach the common rail 4, and the check valve 85 is connected to the fuel passage 4.
It is arranged in the route of 3. The operating pressure of the check valve 85 is set to be higher than the first control pressure P ₁ and lower than the minimum injection pressure, and the check valve 85 determines that the pressure in the common rail 4 is lower than the operating pressure. When that happens, the valve opens,
The fuel in the low-pressure fuel supply pipe 40 is supplied into the common rail 4. The other configurations are the same as those in the third embodiment.

Next, the operation of the pressure accumulation type fuel injection device according to the sixth embodiment will be described. The ECU 12 inputs the detection signal of the pressure sensor 16 and monitors the pressure in the common rail 4. Then, when the pressure in the common rail 4 becomes lower than the minimum injection pressure, the ECU 12 determines that an abnormality has occurred. Therefore, when the ECU 12 is operating normally,
The electromagnetic pressure control valve 84 is controlled so that the fuel pressure supplied from the low-pressure supply pump 9 to the high-pressure supply pump 7 becomes the first control pressure P _1, and when the abnormality occurs, the low-pressure supply pump 9 supplies the high-pressure supply pump 7 to the high-pressure supply pump 7. The electromagnetic pressure control valve 84 is controlled so that the fuel pressure to be controlled becomes the second control pressure P ₂ .

If the ECU 12 determines that the operation is normal, the fuel set to the _first control pressure P ₁ is supplied to the pump chamber 32 of the high pressure supply pump 7 as in the third embodiment, and the high pressure supply is performed. The fuel that has been boosted by the pump 7 is supplied to the common rail 4 through the check valve 6 and the supply pipe 5. By repeating this operation, a high predetermined pressure corresponding to the fuel injection pressure is continuously accumulated in the common rail 4.

Further, when the displacement control valve 11 is opened due to the sliding failure or seizure of the plunger 31 or the disconnection of the electromagnetic coil or the disconnection of the wiring, the high pressure supply pump 7 is in the non-pressure feeding state. . In the non-pressure-feeding state of the high-pressure supply pump 7, the fuel pressure supplied from the low-pressure supply pump 9 to the high-pressure supply pump 7 is the second as in the third embodiment.
Is set to the control pressure of. Then, the second control pressure P ₂
The fuel set to is supplied to the common rail 4 via the high-pressure supply pump 7, and the pressure in the common rail 4 is maintained higher than the minimum injection pressure. At this time, if the pressure in the common rail 4 is lower than the operating pressure of the check valve 85, the check valve 85 operates and high-pressure fuel is sent from the fuel passage 43 into the common rail 4 as well. The internal pressure is maintained above the minimum injection pressure.

Further, when the valve body of the discharge amount control valve 11 is stuck in the seat state, the fuel is not supplied from the low pressure supply pump 9 to the high pressure supply pump 7, so that the high pressure supply pump 7 is in a non-pressurized state. Even in the no-pressure feeding state of this mode,
High-pressure fuel is not supplied to the common rail 4, causing a pressure drop in the common rail 4. Therefore, the ECU 1
2 determines that an abnormality has occurred, and controls the electromagnetic pressure control valve 84 so that the fuel pressure supplied from the low pressure supply pump 9 to the high pressure supply pump 7 becomes the control pressure P ₂ . Then, the pressure of the fuel in the low-pressure fuel supply pipe 40 is maintained at the _second control pressure P ₂ . Then, when the pressure in the common rail 4 becomes lower than the operating pressure of the check valve 85, the check valve 85 opens, and the fuel maintained at the _second control pressure P ₂ is supplied to the fuel passage 4
Is supplied to the common rail 4 via the common rail 4
The internal pressure is maintained above the minimum injection pressure.

Further, when the internal combustion engine is started, the ECU 12 can control the electromagnetic pressure control valve 84 so that the fuel pressure supplied from the low pressure supply pump 9 to the high pressure supply pump 7 becomes the second control pressure P ₂ . Therefore, high-pressure fuel is sent to the common rail 4 via the high-pressure supply pump 7, and the pressure in the common rail 4 can be quickly raised.

Therefore, also in the sixth embodiment, the same effect as that of the fifth embodiment can be obtained.

In each of the above embodiments, the ECU
If 12 detects a pressure drop in the common rail 4 when a no-pressure feeding state occurs from the detection signal of the pressure sensor 16 and determines that it is abnormal and issues a warning to the driver, the driver warns of the abnormality. After receiving the vehicle, the vehicle can be safely driven to a safe place, the accident associated with the occurrence of the non-pressurized state can be safely avoided, and the high-pressure supply pump 7 can be repaired. Further, although the low-pressure supply pump 9 is not specifically described in each of the above-described embodiments, the low-pressure supply pump 9 may be a vane type pump, a trochoid type pump, or a gear type pump.

[0051]

Since the present invention is constituted as described above, it has the following effects.

According to the present invention, the common rail for accumulating the pressurized fuel, the injector for injecting the fuel in the common rail into each cylinder of the internal combustion engine, and the pump chamber into which the fuel flows are provided. Is arranged in the path of a low-pressure fuel supply pipe that communicates the high-pressure supply pump that pressurizes the fuel in the common rail and the fuel chamber in the common rail, and the pump chamber and the fuel tank. A low-pressure supply pump that pumps fuel to the pump chamber and a passage that connects the pump chamber and the low-pressure fuel supply pipe to each other, and a discharge that connects the pump chamber and the low-pressure fuel supply pipe when the valve is opened. In a pressure-accumulation fuel injection device having an amount control valve and an electronic control unit for controlling the opening / closing of the discharge amount control valve to control the fuel pressure in the common rail to a predetermined pressure. A low-pressure fuel return pipe that is branched from the low-pressure fuel supply pipe downstream of the low-pressure supply pump to reach the fuel tank, and the low-pressure fuel return pipe is disposed in the path of the low-pressure fuel return pipe. From the upstream side of the first pressure control valve that sets the pressure of fuel in the supply pipe to a first control pressure that is lower than the lowest injection pressure of the common rail, and the first pressure control valve of the low pressure fuel return pipe. A bypass pipe that branches to reach the fuel tank and a bypass pipe that is arranged in the path of the bypass pipe and that controls the pressure of the fuel in the low-pressure fuel supply pipe to a pressure higher than the minimum injection pressure of the common rail. When the second pressure control valve set to the control pressure of 2 and the high pressure supply pump are pressurelessly fed,
Since the valve switching means for switching the setting of the pressure in the low-pressure fuel supply pipe from the first pressure control valve to the second pressure control valve is provided, the sliding failure or seizure of the plunger, or the electromagnetic coil Even if a non-pressurized state occurs due to a defective seat in the discharge control valve due to a wire break or wire disconnection, the pressure in the common rail is maintained at the minimum injection pressure or higher, and the traveling vehicle stops suddenly due to the non-pressurized state. It is possible to obtain a pressure-accumulation type fuel injection device that can prevent the occurrence of accidents and secure safety measures for the non-pressure-feeding state.

Further, the valve switching means is arranged downstream of the first pressure control valve in the low-pressure fuel return pipe, and the normal discharge amount of the high-pressure supply pump becomes the normal overflow amount. Since it is composed of a flow control valve that operates so as to cut off the flow of fuel in the low-pressure fuel return pipe when added, the pressure in the common rail can be increased quickly even if the high-pressure supply pump is in a non-pressurized state. Moreover, it is possible to maintain the minimum injection pressure or more.

Further, the valve switching means is composed of an electromagnetic switching valve disposed upstream of the first pressure control valve in the low pressure fuel return pipe, and the electromagnetic switching valve is configured to control the pressure in the common rail. Is controlled to be cut off by the electronic control unit so as to cut off the flow of fuel in the low pressure fuel return pipe when the pressure becomes lower than the minimum injection pressure. The internal pressure can be quickly maintained above the minimum injection pressure, and the injection pressure at the time of starting the internal combustion engine can be quickly raised.

Further, a common rail for accumulating the pressurized fuel, an injector for injecting the fuel in the common rail to each cylinder of the internal combustion engine, and a pump chamber into which the fuel flows are provided, and the fuel in the pump chamber is stored in the common rail. A high-pressure supply pump that pumps the fuel in the common rail and pressurizes the fuel in the common rail, and a low-pressure fuel supply pipe that connects the pump chamber and the fuel tank are arranged in a path to pump up the fuel in the fuel tank. A low-pressure supply pump that supplies the pump chamber, a discharge amount control valve that is provided in a passage that communicates the pump chamber and the low-pressure fuel supply pipe, and that communicates the pump chamber and the low-pressure fuel supply pipe when the valve is opened. A low-pressure accumulator type fuel injection device having an electronic control unit for controlling the opening / closing of the discharge amount control valve to control the fuel pressure in the common rail to a predetermined pressure. Inside the low-pressure fuel supply pipe, which is arranged in the path of the low-pressure fuel return pipe branched from the downstream side of the low-pressure supply pump of the fuel supply pipe to reach the fuel tank. Fuel pressure is lower than the minimum injection pressure of the common rail above
Control pressure or a second control pressure that is higher than the lowest injection pressure of the common rail, and the electromagnetic pressure control valve is configured such that the pressure in the common rail becomes lower than the lowest injection pressure. At this time, the pressure of the fuel in the low-pressure fuel supply pipe is controlled by the electromagnetic control unit so as to set it to the second control pressure. Therefore, sliding failure or seizure of the plunger, or disconnection of the electromagnetic coil is caused. Even if the no-pressure feeding state occurs due to a defective seat of the discharge control valve due to wire breakage or wiring breakage, the pressure in the common rail is maintained above the minimum injection pressure, and the traveling vehicle suddenly stops due to the no-pressure feeding state. Accumulation type fuel that can prevent accidents before it occurs, secures safety measures against non-pressurized delivery, and can quickly raise the injection pressure when starting the internal combustion engine. Injection device is obtained.

A fuel passage is provided so as to connect the upstream side of the second pressure control valve of the bypass pipe to the common rail, and the pressure in the common rail is higher than the first control pressure. Further, since the check valve that operates when the pressure becomes lower than the minimum injection pressure is arranged in the path of the fuel passage, sliding failure or seizure of the plunger, disconnection of the electromagnetic coil or disconnection of wiring is caused. In addition to the no-pressure feeding state caused by the defective seat of the discharge amount control valve, the pressure in the common rail is minimum injection even when the valve body of the discharge amount control valve is stuck in the seat state. By maintaining the pressure or more, it is possible to prevent the traveling vehicle from suddenly stopping due to the non-pressurized state, and it is possible to complete the safety measure for the non-pressurized state.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a pressure accumulation type fuel injection device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a pressure accumulation type fuel injection device according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram showing a pressure accumulation type fuel injection device according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram showing a pressure accumulation type fuel injection device according to a fourth embodiment of the present invention.

FIG. 5 is a configuration diagram showing a pressure accumulation type fuel injection device according to a fifth embodiment of the present invention.

FIG. 6 is a configuration diagram showing a pressure accumulation type fuel injection device according to a sixth embodiment of the present invention.

FIG. 7 is a configuration diagram showing a conventional pressure accumulation type fuel injection device.

[Explanation of symbols]

1 engine (internal combustion engine), 2 injectors, 4 common rail, 7 high pressure supply pump, 8 fuel tank, 9
Low-pressure supply pump, 11 discharge control valve, 12 electronic control unit, 32 pump chamber, 40 low-pressure fuel supply pipe,
41 low-pressure fuel return pipe, 42 bypass pipe, 43
Fuel passage, 80 First pressure control valve, 81 Second pressure control valve, 82 Flow control valve, 83 Electromagnetic switching valve, 84
Electromagnetic pressure control valve, 85 check valve.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) F02M 37/00 F02M 47/02 F02M 55/02 350 F02M 63/00

Claims (5)

(57) [Claims] 1. A common rail for accumulating pressurized fuel, an injector for injecting the fuel in the common rail into each cylinder of an internal combustion engine, and a pump chamber into which the fuel flows, the fuel in the pump chamber being supplied to the common rail. Pumped to
A high-pressure supply pump for pressurizing the fuel in the common rail,
A low-pressure supply pump that is disposed in a path of a low-pressure fuel supply pipe that connects the pump chamber and the fuel tank, and pumps up the fuel in the fuel tank to supply the fuel to the pump chamber; and the pump chamber and the low-pressure fuel. A discharge amount control valve that is provided in a passage that communicates with the supply pipe and that communicates the pump chamber and the low-pressure fuel supply pipe when the valve is opened, and the discharge amount control valve is opened / closed to control the fuel pressure in the common rail. In a pressure accumulation type fuel injection device having an electronic control unit for controlling to a predetermined pressure, a low pressure fuel return pipe branched from the low pressure fuel supply pipe downstream of the low pressure supply pump to reach the fuel tank. A first control pressure is disposed in the path of the low-pressure fuel return pipe, and sets the pressure of the fuel in the low-pressure fuel supply pipe to a first control pressure that is lower than the minimum injection pressure of the common rail. A pressure control valve, a bypass pipe branched from an upstream side of the first pressure control valve of the low-pressure fuel return pipe to reach the fuel tank, and a bypass pipe disposed in a path of the bypass pipe, A second pressure control valve that sets the pressure of the fuel in the low-pressure fuel supply pipe to a high-pressure second control pressure that is equal to or higher than the lowest injection pressure of the common rail; and the low-pressure fuel supply when the high-pressure supply pump sends no pressure. The pressure in the pipe is set from the first pressure control valve to the second pressure control valve.
And a valve switching means for switching to the pressure control valve. 2. The valve switching means is arranged downstream of the first pressure control valve in the low-pressure fuel return pipe, and the normal discharge amount of the high-pressure supply pump becomes a normal overflow amount. The pressure-accumulation fuel injection device according to claim 1, wherein the pressure-accumulation fuel injection device comprises a flow control valve that operates so as to interrupt the flow of fuel through the low-pressure fuel return pipe when added. 3. The valve switching means is composed of an electromagnetic switching valve disposed upstream of the first pressure control valve in the low pressure fuel return pipe, and the electromagnetic switching valve has a pressure in the common rail. 2. The pressure-accumulation fuel injection device according to claim 1, wherein the electronic control unit controls opening / closing so that the flow of fuel through the low-pressure fuel return pipe is interrupted when the pressure becomes lower than the minimum injection pressure. 4. A common rail for accumulating pressurized fuel, an injector for injecting fuel in the common rail to each cylinder of an internal combustion engine, and a pump chamber into which fuel flows, the fuel in the pump chamber being stored in the common rail. Pumped to
A high-pressure supply pump for pressurizing the fuel in the common rail,
A low-pressure supply pump that is disposed in a path of a low-pressure fuel supply pipe that connects the pump chamber and the fuel tank, and pumps up the fuel in the fuel tank to supply the fuel to the pump chamber; and the pump chamber and the low-pressure fuel. A discharge amount control valve that is provided in a passage that communicates with the supply pipe and that communicates the pump chamber and the low-pressure fuel supply pipe when the valve is opened, and the discharge amount control valve is opened / closed to control the fuel pressure in the common rail. In a pressure accumulation type fuel injection device having an electronic control unit for controlling to a predetermined pressure, a low pressure fuel return pipe branched from the low pressure fuel supply pipe downstream of the low pressure supply pump to reach the fuel tank. Disposed in the path of the low-pressure fuel return pipe, the pressure of the fuel in the low-pressure fuel supply pipe is lower than the minimum injection pressure of the common rail, that is, the first control pressure or the co-current. An electromagnetic pressure control valve for setting a second control pressure higher than the minimum injection pressure of the rail, and the electromagnetic pressure control valve is configured to operate when the pressure in the common rail becomes lower than the minimum injection pressure. A pressure-accumulation fuel injection device controlled by the electromagnetic control unit so as to set the pressure of the fuel in the low-pressure fuel supply pipe to the second control pressure. 5. The fuel passage has the second portion of the bypass pipe.
Is provided so as to connect the upstream side of the pressure control valve and the common rail, and operates when the pressure in the monrail is higher than the first control pressure and lower than the minimum injection pressure. The pressure-accumulation fuel injection device according to any one of claims 1 to 4, wherein a stop valve is arranged in the path of the fuel passage.