JP2007327485A - Fuel supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel supply system for sufficiently boosting fuel, while minimizing electric power consumption, when starting an engine. <P>SOLUTION: This fuel supply system 100 has an accumulator 12 and a solenoid valve 40 arranged on the downstream side of the accumulator 12. The solenoid valve 40 is closed when stopping operation of the engine 2, and the accumulator 12 stores and maintains pressure equal to delivery pressure of a feed pump 100. The solenoid valve 40 is opened when starting the engine 2, and the fuel stored in the accumulator 12 is supplied to an injection pump 6. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel supply system, and more particularly to a control system at the time of starting.

  In a fuel supply system for supplying fuel to an engine, the fuel is generally prevented from vaporizing. If the fuel is vaporized, problems will occur when the fuel is supplied to the engine by the pump, and the efficiency will be reduced. Therefore, a special mechanism must be provided to supply the fuel to the engine. Because it will not be. In order to prevent vaporization and improve the combustion efficiency in the engine, one having a pressurizing means such as a pump has been proposed.

In these fuel supply systems, when the engine is started, the pressurizing means must be started before the engine, and the injection pump that supplies fuel to the engine needs to be filled with fuel. For this reason, these pressurizing means are operated by an electric motor using a battery as a power source at least at the time of activation.
A pump used as a general pressurizing means has a rated operating voltage of 24V, for example, and does not operate when the supply voltage drops to about 18V. For this reason, a configuration for suppressing necessary battery power consumption so as to operate even when the battery is consumed has been proposed.

An example of a configuration for reducing battery power consumption is disclosed in Patent Document 1. The fuel supply system of Patent Document 1 uses dimethyl ether (C ₂ H ₆ O, hereinafter referred to as DME) as a fuel. In addition to the main path by the high-pressure pump (secondary pump) that operates after the engine is started, a bypass path from the pressurized pump (primary pump) that operates at the time of engine startup with lower power is provided. Only the pump is driven by a battery. With such a configuration, the battery power consumption when starting the engine is reduced to some extent.

JP 2006-46143 A

However, in the conventional fuel supply system as shown in Patent Document 1, in order to suppress power consumption before starting the engine, the boosting capability of the primary pump that operates first is reduced. For this reason, there has been a problem that fuel may not be sufficiently boosted before the engine is started.
For example, if the engine is stopped in a sufficiently warm state and restarted before the engine cools down, the pressure by the primary pump may be insufficient and the DME may be vaporized in the process of being sent to the injection pump There is.
Patent Document 1 also describes that a high-pressure circuit is provided with a shut-off valve and an accumulator. In this case, the accumulator, which is a high-pressure vessel, must be disposed in the middle of the piping of the high-pressure circuit. System mountability on vehicles, machines, facilities, etc. deteriorates. If priority is given to mounting on a vehicle, machine, or facility, the capacity of the accumulator cannot be increased sufficiently, and the fuel supply amount at the time of starting the engine may be insufficient.

  The present invention has been made in order to solve such a problem, and while suppressing the power consumption of the pump at the time of starting the engine, the fuel is sufficiently boosted, and the vehicle, machine, An object is to provide a fuel supply system that can be easily mounted on facilities.

  In order to solve the above-described problems, a fuel supply system according to the present invention includes a fuel tank and a pump that is provided inside the fuel tank and supplies fuel from the fuel tank to an external injection pump of an internal combustion engine. In the fuel supply system, pressure accumulating means provided inside the fuel tank, the fuel accumulating means for supplying the fuel supplied from the pump to the injection pump of the internal combustion engine, and the accumulating means for supplying to the injection pump of the internal combustion engine A first path, which is a fuel path, and an on-off valve provided on the downstream side of the pressure accumulating means, which opens and closes the first path, and the on-off valve is closed when the operation of the internal combustion engine is stopped. The valve is opened when the internal combustion engine is started.

  While the operation of the internal combustion engine is stopped, the on-off valve is closed, and the pressure-accumulating means provided inside the fuel tank stores the fuel boosted by the pump. When the internal combustion engine is started, the on-off valve is opened, and the pressurized fuel is supplied from the pressure accumulating means to the internal combustion engine.

The on-off valve may be closed during operation of the internal combustion engine.
The on-off valve may be opened during operation of the internal combustion engine.
The on-off valve may be provided inside the fuel tank or integrally with the fuel tank.
The on-off valve may be provided outside the fuel tank.

The pressure accumulating means may include a positive displacement compression mechanism.
The pressure accumulating means includes a cylinder, a piston slidably provided inside the cylinder, and a spring that urges the piston in one direction, and the piston resists urging by the pressure of fuel supplied from the pump. Thus, the fuel having a higher pressure than the fuel in the fuel tank may be held in the cylinder by sliding the valve and closing the on-off valve.
The pressure accumulating means includes a cylinder and a bellows provided inside the cylinder so as to be extendable and contractible, and the bellows are elastically contracted by the pressure of fuel supplied from the pump, and the on-off valve is closed to thereby close the fuel tank. A fuel having a higher pressure than the internal fuel may be held in the cylinder.
The fuel supply system may include a second path different from the first path for supplying fuel from the pump to the internal combustion engine.
The fuel supply system may include a pressure accumulating unit or a check valve provided upstream of the first path and in the middle of the second path to prevent fuel from flowing from the pressure accumulating unit to the pump.

The fuel supply system may include an overflow prevention valve downstream of the pressure accumulating means, and the overflow prevention valve may operate based on a pressure difference between fuel upstream and downstream.
The fuel supply system includes an overflow prevention valve downstream of the pressure accumulating means, further includes a pressure sensor downstream of the overflow prevention valve, and the overflow prevention valve operates based on the pressure detected by the pressure sensor. May be.
The fuel supply system may include an overflow prevention valve downstream of the pressure accumulating means, and the overflow prevention valve may operate based on an engine speed detected by an engine speed sensor provided in the internal combustion engine.
The fuel supply system includes a bypass path that is upstream of the overflow prevention valve and communicates with the middle of the first path or the second path, and the bypass path includes an auxiliary valve. The operation may be based on the pressure difference between the upstream and downstream fuels to assist the operation of the overflow prevention valve.
The fuel supply system may include a reservoir that stores fuel upstream of the overflow prevention valve and in the middle of the first path or the second path.

  According to this invention, the fuel supply system includes the pressure accumulating means and the on-off valve provided downstream of the pressure accumulating means, and when the internal combustion engine is started, the on-off valve opens and supplies fuel from the pressure accumulating means to the internal combustion engine. While suppressing the power consumption at the time of starting the internal combustion engine, the pressure of the fuel can be sufficiently increased and the mountability of the fuel supply system on a vehicle, machine, facility or the like can be improved.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1 FIG.
First, the configuration of a power generation system including a fuel supply system 100 according to Embodiment 1 of the present invention will be described with reference to FIG. The power generation system is mounted on a vehicle and includes an engine 2 that is an internal combustion engine and a fuel supply system 100 that supplies fuel to the engine 2.
The engine 2 is a diesel engine. The fuel for the engine 2 is DME.

The fuel supply system 100 includes a fuel tank 4 that stores fuel, an injection pump 6 that injects fuel supplied from the fuel tank 4 into the engine 2, and a pipe 8 that connects the fuel tank 4 and the injection pump 6. .
The fuel tank 4 includes a housing 4a that constitutes an outer wall thereof, and stores fuel in a storage space 4b that is covered by the housing 4a. The pressure of the fuel in the fuel tank 4 varies depending on the temperature, and is usually about 0.2 to 0.8 MPa.

Inside the fuel tank 4, a feed pump 10 and an accumulator 12 that is a pressure accumulating means having a positive displacement compression mechanism are provided to pressurize and send fuel from the fuel tank 4. The pipe 8 includes a feed pump side pipe 8 a connected to the feed pump 10, an accumulator side pipe 8 b connected to the accumulator 12, a common pipe that connects the feed pump side pipe 8 a and the accumulator side pipe 8 b and the injection pump 6. 8c.
That is, the fuel supply system 100 passes from the feed pump 10 via the accumulator 12 to the injection pump 6 via the accumulator 12 and the accumulator side pipe 8b, which is a path for supplying fuel to the injection pump 6. And a feed pump side pipe 8a which is a path for supplying fuel to the injection pump 6.
Here, the first path for supplying fuel from the accumulator 12 to the injection pump 6 is the accumulator side pipe 8b and the pipe 8c, and the second path for supplying fuel from the feed pump 10 to the injection pump 6 is the feed pump side pipe 8a. And the pipe 8c.
Although not shown, the injection pump 6 and the fuel tank 4 are also connected by a return pipe that is a pipe different from the pipe 8 for returning surplus fuel to the fuel tank 4.

The feed pump 10 includes a suction port 10a, sucks fuel from the suction port 10a, and discharges the fuel to the feed pump side pipe 8a. The feed pump 10 functions as a pressurizing unit for the injection pump 6. That is, the pressurization is performed to a pressure higher than the saturation pressure of the fuel when the injection pump 6 becomes high temperature, that is, a pressure at which the fuel does not vaporize. When the fuel is DME, this pressurization is performed to about 3 MPa, for example. The injection pump 6 may normally have a maximum temperature of about 80 ° C. due to factors such as receiving heat generated by the engine 2 and self-sliding heat generation. If the pressure is about 3 MPa, vaporization does not occur.
The feed pump 10 is driven by an electric motor that is supplied with electric power from a battery. When the engine 2 is started, the feed pump 10 is controlled not to operate until the rotational speed of the engine 2 reaches a predetermined value. . That is, the feed pump 10 does not consume battery power when the engine 2 is started.
The feed capacity of the feed pump 10 may be the same as that of a conventional feed pump, and is, for example, about 30 liters / hour.

  The accumulator 12 includes a spring 22 having one end attached to the feed pump 10, and a hollow bottomed cylindrical piston 20 is attached to the other end of the spring 22. Further, the accumulator 12 includes a hollow bottomed cylindrical cylinder 14 that constitutes an outer wall of the accumulator 12, and an open end of the cylinder 14 is attached to the feed pump 10. The piston 20 can slide inside the cylinder 14, and the spring 22 expands and contracts in response to this sliding.

The internal space of the accumulator 12 is partitioned into a space on the side where the spring 22 is disposed and a space on the opposite side as viewed from the piston 20, and the side where the spring 22 is disposed is the low pressure chamber 30. The opposite side is a high pressure chamber 32.
The spring 22 biases the piston 20 toward the high pressure chamber 32 side. That is, the piston 20 slides to the feed pump 10 side when the fuel pressure in the high pressure chamber 32 increases, and slides to the opposite side of the feed pump 10 when the fuel pressure in the high pressure chamber 32 drops.

  The piston 20 has a protrusion 20 a on the outer side of its end face, that is, on the side opposite to the spring 22. For this reason, when the spring 22 is extended to some extent, the projection 20a comes into contact with the end surface 14a of the cylinder 14 to prevent further movement of the piston 20, and the high pressure chamber side end 16b of the accumulator internal passage 16 is blocked by the piston 20. To prevent accidents.

An accumulator passage 16 is provided as a pipe that penetrates the inside of the peripheral wall of the cylinder 14. A feed pump side end 16 a that is one end of the accumulator passage 16 is connected to the feed pump 10, and a high pressure chamber side end 16 b that is the other end is connected to the high pressure chamber 32. That is, the feed pump 10 discharges fuel to the feed pump side pipe 8 a as described above, and also discharges fuel to the accumulator inner passage 16, thereby supplying fuel to the high pressure chamber 32.
Further, a check valve 18 for preventing the backflow of fuel from the high pressure chamber 32 of the accumulator 12 to the feed pump 10 is provided in the middle of the accumulator passage 16.
The cylinder 14 is provided with a communication hole 24 that allows the storage space 4 b and the low pressure chamber 30 to communicate with each other. When the fuel flows through the communication hole 24, the pressure in the storage space 4b and the pressure in the low pressure chamber 30 are always kept the same.

An electromagnetic valve 40 is provided as an on-off valve in the middle of the accumulator side pipe 8b, that is, downstream of the accumulator 12. The electromagnetic valve 40 is built in the fuel tank 4, that is, provided inside the fuel tank 4. The electromagnetic valve 40 is attached to the housing 4a as shown in FIG. 1, for example, but may be provided inside the fuel tank 4 separately from the housing 4a. This electromagnetic valve 40 opens and closes the path of fuel supplied from the accumulator 12 to the engine 2.
The solenoid valve 40 is opened and closed by being controlled by a control device (not shown) using power supplied from the battery as a power source. Here, the electric power consumed by the solenoid valve 40 is smaller than the electric power consumed when the pump for boosting the fuel such as the feed pump 10 is driven by a battery.

Next, the flow of operation of the fuel supply system 100 according to Embodiment 1 of the present invention will be described with reference to FIG. FIGS. 2A to 2C are views showing the operation around the accumulator 12 along the operation flow of the fuel supply system 100 of FIG.
FIG. 2A shows a state where the engine 2 is in operation. The feed pump 10 supplies fuel to the injection pump 6 via the feed pump side pipe 8a, and the electromagnetic valve 40 is closed. Therefore, the fuel sent from the feed pump 10 to the high pressure chamber 32 via the accumulator passage 16 is stored in the high pressure chamber 32 as it is, and the pressure in the high pressure chamber 32 is the same as the discharge pressure of the feed pump 10 during operation of the engine 2. The pressure rises to, for example, about 3 MPa. As described above, the piston 20 is held down in the cylinder 14 by the pressure increase during the operation of the engine 2, and the fuel is stored in the high pressure chamber 32 of the cylinder 14. Thus, the accumulator 12 accumulates pressure.
Further, due to the pressure difference between the high pressure chamber 32 and the low pressure chamber 30, the piston 20 overcomes the bias of the spring 22 and slides toward the feed pump 10, and the volume of the high pressure chamber 32 increases.

FIG. 2B shows a state where the engine 2 is stopped. When the engine 2 stops, the feed pump 10 also stops. Here, the electromagnetic valve 40 remains closed, and the check valve 18 prevents the back flow of fuel, so that the pressure in the high pressure chamber 32 is maintained.
As described above, the pressure of the fuel supplied from the feed pump 10 causes the piston 20 to slide against the bias of the spring 22 and closes the solenoid valve 40, so that the pressure is higher than the fuel in the fuel tank 4. Fuel is held in the cylinder 14.

FIG. 2C shows a state when the engine 2 is started. When the key switch is in the start state (ST state) by the driver's key operation, the electromagnetic valve 40 is driven by the battery and opens. As a result, the fuel in the high-pressure chamber 32 can flow out through the pipe 8, and flows out as the piston 20 slides to the opposite side of the feed pump 10 by being biased by the spring 22.
As a result, the pressure in the pipe 8 is increased to the pressure stored in the accumulator 12, that is, the discharge pressure of the feed pump 10 during operation of the engine 2. That is, even if the injection pump 6 is at a high temperature such as when the engine 2 is operating, the pressure is such that fuel is not vaporized when being sucked into the injection pump 6 from the pipe 8. For this reason, even if it is a restart immediately after the engine 2 stops, fuel vaporization does not occur. In this way, the accumulator 12 supplies the pressurized fuel to the injection pump 6.

  Here, the volume of the high pressure chamber 32 when the engine 2 is stopped is larger than the volume of the pipe 8, and when the solenoid valve 40 is opened, the volume of the high pressure chamber 32 decreases due to the sliding of the piston 20. Even if the electromagnetic valve 40 is opened, the pressure stored in the accumulator 12 is propagated into the pipe 8 with almost no change.

  The starter operates simultaneously with the opening of the solenoid valve 40, cranking torque is generated, the crankshaft rotates, and the fuel boosted and supplied to the injection pump 6 as described above is injected into the engine 2. The The injected fuel is ignited and the start of the engine 2 is completed.

When a predetermined time, for example, 5 seconds elapses after the engine 2 is started, the electromagnetic valve 40 is closed and the feed pump 10 starts operating. As a result, the accumulator 12 again accumulates pressure as described with reference to FIG. Further, since the solenoid valve 40 is closed when the feed pump 10 starts to operate, the fuel discharged from the feed pump 10 is quickly supplied to the injection pump 6 from the feed pump side pipe 8a.
In addition, it is preferable on safety, such as prevention of fuel leakage, that the solenoid valve 40 is closed when not energized.

  As described above, the fuel supply system 100 according to Embodiment 1 includes an accumulator 12 provided in the fuel tank 4 and an electromagnetic valve having a small power consumption provided between the accumulator 12 and the injection pump 6. 40. First, when the engine 2 is stopped, the accumulator 12 stores and maintains a pressure equal to the discharge pressure of the feed pump 10 because the electromagnetic valve 40 is closed. When the engine 2 is started, the electromagnetic valve 40 is opened, so that fuel having a pressure equal to the discharge pressure of the feed pump 10 stored in the accumulator 12 is supplied to the injection pump 6. As a result, the fuel supply system 100 can perform sufficient pressure increase such that the fuel is not vaporized during the suction process of the injection pump 6, for example, about 3 MPa.

  Further, since the feed pump 10 is not started until the rotational speed of the engine 2 reaches a predetermined value, the power of the battery is not consumed when the engine 2 is started, that is, when cranking torque is generated. Furthermore, the power consumption of the solenoid valve 40 is lower than that of the fuel boosting pump. Thus, the fuel supply system 100 can suppress the power consumption when starting the engine 2 to be small.

In the fuel supply system 100, the accumulator 12 is provided in the fuel tank 4.
In the conventional fuel supply system, in the configuration in which the accumulator is provided outside the fuel tank, it is necessary to attach the accumulator to the pipe between the feed pump and the injection pump. In addition, in order to mount the accumulator outside the fuel tank, it is necessary to prepare a space for that purpose, and it is difficult to increase the capacity of the accumulator. Furthermore, if the capacity of the accumulator is increased, a large amount of fuel leaks if the piping around the accumulator is broken.
On the other hand, in the fuel supply system 100, since the accumulator 12 is built in the fuel tank 4, the mountability is improved. Further, the capacity of the accumulator 12 can be increased regardless of the space outside the fuel tank 4. Furthermore, even when the pipe is broken, the leakage of fuel can be suppressed to a relatively small amount.

  Further, in the fuel supply system 100, since the electromagnetic valve 40 is also provided inside the fuel tank 4, it is not necessary to prepare a space for the electromagnetic valve 40 outside, and the configuration related to piping can be further simplified. it can.

  As described above, the feed pump 10 is started after the engine 2 is started. However, since the fuel from the accumulator 12 is supplied to the injection pump 6 when the engine 2 is started, the fuel sent from the feed pump 10 is supplied. The engine 2 can be started without waiting for the fuel to reach the injection pump 6.

In the first embodiment described above, the following modifications can be made.
In the first embodiment, the electromagnetic valve 40 is closed when a predetermined time elapses after the engine 2 is started. As a modification, the solenoid valve 40 may not be closed during operation of the engine 2 but may be closed when the engine 2 is stopped.
By adopting such a configuration, fuel is always supplied by two systems of the feed pump side pipe 8a and the accumulator side pipe 8b during operation of the engine 2, so that the feed pump 10 is compared with the supply of the single system. , And the vibration of the pipe 8 can be further reduced. When the solenoid valve 40 is closed only when the engine 2 is stopped, the feed pump-side piping 8a is not provided, and all the fuel discharged from the feed pump 10 can be supplied to the injection pump 6 via the accumulator 12. . With such a configuration, the discharge pulsation is reduced by the movement of the piston 20 of the accumulator 12, and the vibration of the pipe 8 can be further reduced.

In the first embodiment, the feed pump side pipe 8a and the accumulator side pipe 8b are attached to different portions of the fuel tank 4 as different pipes. As a variant, these may be a single pipe outside the fuel tank 4. That is, the feed pump side pipe 8 a and the accumulator side pipe 8 b may merge inside the fuel tank 4, and a single pipe may connect the fuel tank 4 and the injection pump 6.
By adopting such a configuration, the piping configuration outside the fuel tank 4 can be simplified.

Embodiment 2. FIG.
Next, the configuration of the fuel supply system 102 according to Embodiment 2 of the present invention will be described with reference to FIG.
In the fuel supply system 102 according to the second embodiment of the present invention, the accumulator passage 16 and the check valve 18 provided in the accumulator 12 in the first embodiment are provided outside the accumulator 12, The shape has been changed. Further, it is assumed that fuel supply system 102 is mounted on a vehicle as in the first embodiment.
In the second embodiment, the same reference numerals as those in FIGS. 1 and 2 are the same or similar components, and thus detailed description thereof is omitted.

The fuel supply system 102 according to Embodiment 2 includes a fuel tank 4 and a pipe 82 that connects the fuel tank 4 and the injection pump 6.
A feed pump 10 and an accumulator 122 are provided inside the fuel tank 4, and the feed pump 10, the accumulator 122, and the injection pump 6 are connected by a pipe 82. The pipe 82 includes a feed pump side pipe 82 a connected to the feed pump 10, an accumulator side pipe 82 b connected to the accumulator 122, and a pipe 82 c connected to the injection pump 6 and extending into the fuel tank 4. Further, the pipe 82c is connected to the feed pump side pipe 82a in the fuel tank 4, and is further connected to the accumulator side pipe 82b at the connection point. That is, in the second embodiment, the pipe 82 is configured such that the feed pump side pipe 82a and the pipe 82c are main pipes that form a main path for supplying fuel from the feed pump 10 to the injection pump 6, and the accumulator side pipe 82b is in the middle of the main pipe. It is the structure made into the branch piping which makes more branch paths. A check valve 18 is provided in the middle of the feed pump side pipe 82a, that is, upstream of the accumulator side pipe 82b.

Here, the first path for supplying fuel from the accumulator 122 to the injection pump 6 is the accumulator side pipe 82b and the pipe 82c, and the second path for supplying fuel from the feed pump 10 to the injection pump 6 is the feed pump side pipe 82a. And the pipe 82c.
Although not shown, the injection pump 6 and the fuel tank 4 are also connected by a return pipe that is a pipe different from the pipe 82 for returning surplus fuel to the fuel tank 4.

The accumulator 122 has the same configuration as the accumulator 12 in the first embodiment. However, in the first embodiment, the accumulator passage 16 and the check valve 18 which are pipes penetrating the inside of the peripheral wall of the cylinder 14 included in the accumulator 12 are provided outside the accumulator 12. is there. That is, the in-accumulator passage 16 is integrated with the accumulator side pipe 82 b, and the check valve 18 is moved in the middle of the feed pump side pipe 82 a upstream of the accumulator 122.
An overflow prevention valve 50 is provided in the middle of the pipe 82 c, that is, in the housing 4 a of the fuel tank 4. Further, in the middle of the pipe 82 c, the electromagnetic valve 40 is provided outside the fuel tank on the downstream side of the overflow prevention valve 50.

  Here, the overflow prevention valve 50 will be described. The overflow prevention valve 50 is a pressure valve that operates based on the difference between the fuel pressure upstream of the overflow prevention valve 50 and the fuel pressure downstream, and restricts the fuel supply downstream of the overflow prevention valve 50. In other words, this is an emergency shut-off device that prevents leakage of fuel due to damage to the pipe 82 c downstream of the overflow prevention valve 50. Further, the overflow prevention valve 50 is provided in the middle of the pipe 82 c that connects the feed pump 10 and the injection pump 6. Further, normally, the overflow prevention valve 50 is provided in the housing 4 a of the fuel tank 4, and the leakage of fuel from the pipe 82 c outside the fuel tank 4 can be prevented.

  The operation is as follows. The fuel pressure in the pipe 82c on the upstream side of the overflow prevention valve 50 is the first pressure P1, and the fuel pressure in the pipe 82c on the downstream side is the second pressure P2. This is performed by a differential pressure with 2 pressure P2. For example, the overflow prevention valve 50 is normally opened. Here, in the case where fuel leaks due to breakage such as cracks or perforations occurring in the middle of the pipe 82c, that is, downstream of the overflow prevention valve 50, the second pressure P2 is reduced and the first pressure P1 is changed to the first pressure P1. The reference pressure Pa is higher than the two pressures P2 (P1−P2 ≧ a). At this time, the overflow prevention valve 50 operates and closes, and stops the supply of fuel downstream thereof. The reference pressure Pa is appropriately set in advance from the viewpoint of safety.

Next, the operation of the fuel supply system 102 according to Embodiment 2 of the present invention will be described with reference to FIG. FIGS. 4A to 4C are views showing the operation around the accumulator 122 in the operation of the fuel supply system 102 of FIG.
FIG. 4A shows a state where the engine 2 is in operation. The feed pump 10 supplies fuel to the injection pump 6 via the feed pump side pipe 82a and the pipe 82c, and further supplies fuel to the high pressure chamber 322 in the accumulator 122 via the feed pump side pipe 82a and the accumulator side pipe 82b. send. The electromagnetic valve 40 provided in the middle of the pipe 82c is opened. The fuel sent from the feed pump 10 to the high pressure chamber 322 is stored in the high pressure chamber 322 as it is. Further, the pressure in the high pressure chamber 322 increases to the same pressure as the discharge pressure of the feed pump 10 during operation of the engine 2, for example, about 3 MPa. As described above, the pressure during the operation of the engine 2 keeps the piston 20 pushed down in the cylinder 142, and fuel is stored in the high pressure chamber 322 of the cylinder 142. In this way, the accumulator 122 accumulates pressure.
Further, due to the pressure difference between the high pressure chamber 322 and the low pressure chamber 302, the piston 20 overcomes the bias of the spring 22 and slides toward the feed pump 10 side, and the volume of the high pressure chamber 322 increases.

FIG. 4B shows a state where the engine 2 is stopped. When an instruction to stop the engine 2 during operation is given, the solenoid valve 40 is closed and the engine 2 is stopped. When the engine 2 stops, the feed pump 10 also stops. Here, the electromagnetic valve 40 is closed, and the check valve 18 prevents the fuel from flowing back to the feed pump 10, so that the pressure in the high-pressure chamber 322 is maintained.
As described above, the pressure of the fuel supplied from the feed pump 10 causes the piston 20 to slide against the bias of the spring 22 and closes the solenoid valve 40, so that the pressure is higher than the fuel in the fuel tank 4. Fuel is held in the cylinder 142.

  FIG. 4C shows a state when the engine 2 is started. When the engine 2 is started, first, the electromagnetic valve 40 is driven by a battery and opened. As a result, the fuel in the high-pressure chamber 322 can flow out through the accumulator side pipe 82 b and flows out as the piston 20 slides to the opposite side of the feed pump 10 by being biased by the spring 22. Since the subsequent operation is the same as that of the first embodiment, the description thereof is omitted. In addition, after the start of the engine 2 is completed, in the second embodiment, the electromagnetic valve 40 remains open.

  As described above, the fuel supply system 102 according to the second embodiment is provided between the accumulator 122 provided in the fuel tank 4 and between the accumulator 122 and the injection pump 6 as in the first embodiment. And an electromagnetic valve 40. First, when the engine 2 is stopped, the accumulator 122 stores and maintains a pressure equal to the discharge pressure of the feed pump 10 because the electromagnetic valve 40 is closed. When the engine 2 is started, the solenoid valve 40 is opened, so that fuel having a pressure equal to the discharge pressure of the feed pump 10 stored in the accumulator 122 is supplied to the injection pump 6. As a result, the fuel supply system 102 can perform sufficient pressure increase so that the fuel is not vaporized during the suction process of the injection pump 6, for example, about 3 MPa.

Further, the fuel supply system 102 according to the second embodiment can obtain the same effects as those of the first embodiment.
Further, in the second embodiment, the feed pump side pipe 82a and the accumulator side pipe 82b merge inside the fuel tank 4, and only a single pipe 82c exists outside the fuel tank 4 and is connected to the injection pump 6. ing. Therefore, the piping configuration outside the fuel tank 4 is simplified.
The pipe 82 is composed of a feed pump side pipe 82a and a pipe 82c, and is composed of a main pipe that forms a main path for supplying fuel from the feed pump 10 to the injection pump 6 and an accumulator side pipe 82b that branches from the middle of the main pipe. It takes the form comprised by the branch piping which makes a path | route. In this embodiment, since fuel is supplied from the feed pump 10 to the injection pump 6 by a single pipe, pressure loss due to the pipe 82 in the fuel supply can be reduced.

Further, during operation of the engine 2, the accumulator 122 communicates with the pipe 82, so that the fuel discharge pulsation is reduced by the movement of the piston 20 in the accumulator 122 according to the fuel pressure.
Further, the electromagnetic valve 40 is always opened during operation of the engine 2, but the electromagnetic valve 40 is closed when the engine 2 is stopped. For this reason, when the engine 2 is stopped, if the pipe 82c downstream of the electromagnetic valve 40 is damaged such as a crack or a hole, and fuel leaks, the fuel leakage downstream of the electromagnetic valve 40 can be suppressed.

Further, when the vehicle accelerates rapidly, that is, when the demand for fuel increases rapidly, the feed pump 10 increases the amount of fuel supplied to the injection pump 6, and the injection pump 6 also supplies fuel to the engine 2. Increase the amount. At this time, an instruction to increase the fuel supply amount is sent to the feed pump 10 and the injection pump 6 from a control circuit (not shown) outside the fuel supply system 102. However, when there is a difference in the communication speed of these instructions for each pump, a deviation occurs in the operation timing of each pump.
Therefore, for example, it is assumed that the communication speed of the instruction for the feed pump 10 is slower than the communication speed of the instruction for the injection pump 6. At this time, since the operation of the feed pump 10 is delayed with respect to the operation of the injection pump 6 after an instruction to increase the fuel supply amount to each pump by the control circuit is generated, the fuel consumption in the pipe 82 increases the supply amount. Turn around. In other words, the pressure in the fuel in the pipe 82 is lowered, and the fuel in the pipe 82 may be pressured down to a vaporizing pressure.

In the second embodiment, the high pressure chamber 322 of the accumulator 122 is in communication with the pipe 82 during the operation of the engine 2. Therefore, in the high pressure chamber 322 of the accumulator 122, the fuel pressure supplied from the feed pump 10 overcomes the bias of the spring 22 and causes the piston 20 to slide toward the feed pump 10 side. Further, this state is maintained, and fuel is stored in the high pressure chamber 322. Therefore, in the fuel supply system 102, when the demand for fuel sharply increases, the piston 20 inside the accumulator 122 slides due to the bias of the spring 22, and the fuel stored in the accumulator 122 is supplied to the pipe 82. .
Further, the volume of the high pressure chamber 322 of the accumulator 122 is larger than the volume of the pipe 82. Therefore, when the fuel stored in the high pressure chamber 322 is supplied to the pipe 82, the piston 20 slides by being biased by the spring 22, and the volume of the high pressure chamber 322 decreases, so that the fuel is stored in the high pressure chamber 322. Even if fuel is supplied, the pressure stored in the accumulator 122 is transmitted to the pipe 82 with almost no change. Therefore, it is possible to prevent the fuel in the pipe 82 from being lowered.

Embodiment 3 FIG.
Next, the configuration of the fuel supply system 103 according to Embodiment 3 of the present invention will be described with reference to FIG.
A fuel supply system 103 according to Embodiment 3 of the present invention is provided with an electromagnetic valve 51 in place of the electromagnetic valve 40 and the overflow prevention valve 50 in Embodiment 2. Further, a pressure sensor 52 is provided in the pipe 82c.
In the third embodiment, the same reference numerals as those in FIGS. 1 to 4 are the same or similar components, and the detailed description thereof is omitted.

  In the fuel supply system 103 according to the third embodiment, the solenoid valve 51 is provided in the middle of the pipe 82c, that is, in the housing 4a of the fuel tank 4 in the configuration excluding the solenoid valve 40 and the overflow prevention valve 50 in the second embodiment. Further, a pressure sensor 52 is provided on the downstream side of the electromagnetic valve 51. Further, the electromagnetic valve 51 has the operations of the electromagnetic valve 40 and the overflow prevention valve in the second embodiment. Furthermore, the solenoid valve 51 and the pressure sensor 52 are electrically connected to the ECU 3 of the vehicle. Therefore, the description of the same components as those in Embodiment 2 is omitted.

Here, the electromagnetic valve 51 in the third embodiment will be described.
The solenoid valve 51 is operated by control from the ECU 3 of the vehicle.
The solenoid valve 51 is operated by the pressure value of the fuel detected by the pressure sensor 52 provided in the pipe 82c on the downstream side, and restricts the fuel supply downstream from the solenoid valve 51. That is, as shown in FIG. 5, the electromagnetic valve 51 is normally opened, the pressure value detected by the pressure sensor 52 is sent to the ECU 3, and the information on the sent pressure value is processed by the ECU 3. When the pressure value information indicates an abnormality, the electromagnetic valve 51 is actuated by a command from the ECU 3 to close the valve. That is, the solenoid valve 51 operates as an overflow prevention valve.

For example, when fuel leakage occurs due to breakage such as cracks or perforations generated in the middle of the pipe 82 c, that is, downstream of the electromagnetic valve 51, the fuel pressure downstream of the electromagnetic valve 51 decreases. Therefore, when the pressure drop is detected by the pressure sensor 52 and the pressure value of the fuel sent to the ECU 3 becomes lower than the reference pressure, the electromagnetic valve 51 is closed by the command from the ECU 3, and the fuel is supplied downstream from it. Stop.
Moreover, since the solenoid valve 51 is controlled by the ECU 3 based on information sent from the vehicle, it can also operate as the solenoid valve 40 in the second embodiment. Therefore, the solenoid valve 51 performs the same valve opening / closing operation as the solenoid valve 40, opens during operation of the engine 2, and closes when the engine 2 is stopped.
Therefore, the solenoid valve 51 in the third embodiment has both the operation of the overflow prevention valve and the solenoid valve 40.
The solenoid valve 51 is preferably closed when not energized for safety, such as prevention of fuel leakage.

  The other operations of the fuel supply system 103 according to the third embodiment of the present invention are the same as those in the second embodiment, and thus the description thereof is omitted.

  As described above, the fuel supply system 103 according to the third embodiment is similar to the first and second embodiments described above in that the accumulator 122 provided in the fuel tank 4 is interposed between the accumulator 122 and the injection pump 6. And an electromagnetic valve 51 provided. First, the accumulator 122 stores and maintains a pressure equal to the discharge pressure of the feed pump 10 because the electromagnetic valve 51 is closed while the engine 2 is stopped. When the engine 2 is started, the solenoid valve 51 is opened, so that fuel having a pressure equal to the discharge pressure of the feed pump 10 stored in the accumulator 122 is supplied to the injection pump 6. As a result, the fuel supply system 103 can perform sufficient pressure increase such that the fuel is not vaporized during the suction process of the injection pump 6, for example, about 3 MPa.

Further, the fuel supply system 103 according to the third embodiment can obtain the same effects as those of the first and second embodiments.
In addition, since the solenoid valve 51 in the third embodiment has the operations of the solenoid valve 40 and the overflow prevention valve 50 in the second embodiment, the number of valves in the pipe 82 can be reduced as compared with the second embodiment. ing. By reducing the number of valves in the pipe 82, the pressure loss in the fuel supply can be reduced.
Further, the electromagnetic valve 51 is always opened during operation of the engine 2 as with the electromagnetic valve 40 in the second embodiment, but is closed when the engine 2 is stopped. Therefore, when the engine 2 in which the solenoid valve 51 cannot be operated is stopped, the pipe 82c downstream from the solenoid valve 51 is damaged such as a crack or a hole, and fuel leaks. Leakage can be suppressed.

Embodiment 4 FIG.
Next, the configuration of the fuel supply system 104 according to Embodiment 4 of the present invention will be described with reference to FIG.
The fuel supply system 104 according to the fourth embodiment of the present invention is provided with an electromagnetic valve 51 in place of the electromagnetic valve 40 and the overflow prevention valve 50 according to the second embodiment. Further, an engine speed sensor 53 is provided in the engine 2.
In the fourth embodiment, the same reference numerals as those in FIGS. 1 to 5 are the same or similar components, and thus detailed description thereof is omitted.

  In the fuel supply system 104 according to the fourth embodiment, the solenoid valve 51 is provided in the middle of the pipe 82c, that is, in the housing 4a of the fuel tank 4 in the configuration excluding the solenoid valve 40 and the overflow prevention valve 50 in the second embodiment. Further, the engine 2 is provided with an engine speed sensor 53. Further, the electromagnetic valve 51 has the operations of the electromagnetic valve 40 and the overflow prevention valve in the second embodiment. Furthermore, the solenoid valve 51 and the engine speed sensor 53 are electrically connected to the ECU 3 of the vehicle. Therefore, the description of the same components as those in Embodiment 2 is omitted.

Here, the electromagnetic valve 51 in the fourth embodiment will be described.
The solenoid valve 51 is operated by control from the ECU 3 of the vehicle.
The solenoid valve 51 is operated by an engine speed signal detected by an engine speed sensor 53 provided in the engine 2, and restricts fuel supply downstream from the solenoid valve 51. That is, as shown in FIG. 6, the solenoid valve 51 is normally opened, the engine speed signal detected by the engine speed sensor 53 is sent to the ECU 3, and the information of the sent engine speed signal is the ECU 3 It is processed by. When the engine speed signal indicates an abnormality, the electromagnetic valve 51 is actuated by a command from the ECU 3 to close the valve. That is, the solenoid valve 51 operates as an overflow prevention valve.

For example, when fuel leaks due to breakage such as a crack or a hole occurring in the middle of the pipe 82c, that is, downstream of the electromagnetic valve 51, the engine 2 stops. Therefore, when the engine speed signal detected by the engine speed sensor 53 and sent to the ECU 3 indicates 0, the solenoid valve 51 is closed by a command from the ECU 3, and the supply of fuel downstream is stopped.
Moreover, since the solenoid valve 51 is controlled by the ECU 3 based on information sent from the vehicle, it can also operate as the solenoid valve 40 in the second embodiment. Therefore, the solenoid valve 51 performs the same valve opening / closing operation as the solenoid valve 40, opens during operation of the engine 2, and closes when the engine 2 is stopped.
Therefore, the electromagnetic valve 51 in the fourth embodiment has both the operation of the overflow prevention valve and the electromagnetic valve 40.

  The other operations of the fuel supply system 104 according to the fourth embodiment of the present invention are the same as those of the second embodiment, and thus the description thereof is omitted.

As described above, the fuel supply system 104 according to the fourth embodiment includes the accumulator 122 provided inside the fuel tank 4 and the accumulator 122 and the injection pump 6 as in the first to third embodiments. And an electromagnetic valve 51 provided. First, the accumulator 122 stores and maintains a pressure equal to the discharge pressure of the feed pump 10 because the electromagnetic valve 51 is closed while the engine 2 is stopped. When the engine 2 is started, the solenoid valve 51 is opened, so that fuel having a pressure equal to the discharge pressure of the feed pump 10 stored in the accumulator 122 is supplied to the injection pump 6. As a result, the fuel supply system 104 can perform sufficient pressure increase such that the fuel is not vaporized during the suction process of the injection pump 6, for example, about 3 MPa.
Moreover, since the fuel supply system 104 according to Embodiment 4 can obtain the same effects as those of Embodiments 1 to 3, description thereof is omitted.

Embodiment 5 FIG.
Next, the configuration of a power generation system including a fuel supply system 105 according to Embodiment 5 of the present invention will be described with reference to FIG.
The fuel supply system 105 according to Embodiment 5 of the present invention is obtained by changing the accumulator 122 having the piston-type internal structure from the accumulator 125 having the bellows-type internal structure in Embodiment 2. Furthermore, in Embodiment 2, the electromagnetic valve 40 provided outside the fuel tank 4 is provided in the middle of the accumulator side pipe 82b inside the fuel tank 4, and the operation of the overflow prevention valve 50 is performed in the feed pump 10. An overflow prevention assist valve 54 is provided as an auxiliary valve for assisting.
In the fifth embodiment, the same reference numerals as those in FIGS. 1 to 6 are the same or similar components, and the detailed description thereof is omitted.

A fuel supply system 105 according to Embodiment 5 includes a fuel tank 4 and a pipe 82 that connects the fuel tank 4 and the injection pump 6.
Inside the fuel tank 4 is provided an accumulator 125 which is a pressure accumulating means provided with a feed pump 15 and a positive displacement compression mechanism. Moreover, since the structure of the piping 82, the check valve 18, and the overflow prevention valve 50 is the same as that of Embodiment 2, description is abbreviate | omitted.

  The feed pump 15 is the same as that of the first embodiment, but has a bypass path 82d communicating with the storage space 4b in the fuel tank 4 and the feed pump discharge path 82e inside, and opens and closes this path. An overflow prevention assist valve 54 that is an auxiliary valve for assisting the operation of the flow prevention valve is provided.

Here, the bypass path 82d and the overflow prevention assist valve 54 will be described.
The bypass path 82d is a path that connects the storage space 4b in the fuel tank 4 and the feed pump discharge path 82e. Further, the feed pump discharge passage 82e forms a second passage of the fuel supply passage and communicates with the overflow prevention valve 50. Accordingly, one of the locations where the bypass path 82d communicates is not limited to the feed pump discharge path 82e, but is located upstream of the overflow prevention valve 50 and in the middle of the second path of the pipe 82 or the first path. In the middle of this, it is sufficient to communicate with the overflow prevention valve 50.

The overflow prevention assist valve 54 is provided in the middle of the bypass path 82d, and operates due to the pressure drop of the fuel on the downstream side of the overflow prevention assist valve 54. The fuel in the fuel tank 4 on the upstream side is made downstream. To supply.
The operation is as follows: the fuel pressure in the bypass passage 82d upstream of the overflow prevention assist valve 54 is the third pressure P3, and the fuel pressure in the downstream bypass passage 82d is the fourth pressure P4. This is performed by the differential pressure between the pressure P3 and the fourth pressure P4. That is, the overflow prevention assist valve 54 is normally closed, but if the third pressure P3 is higher than the fourth pressure P4 by the reference pressure Pb (P3-P4 ≧ Pb), the overflow prevention assist valve 54 is closed. Is opened to supply fuel downstream via the bypass path 82d.
The reference pressure Pb is appropriately set in advance from the viewpoint of safety.
Further, since the overflow prevention assist valve communicates with the storage space 4b in the fuel tank 4, the fuel pressure in the storage space 4b becomes the third pressure P3.

That is, for example, when the engine 2 is stopped, if a breakage such as a crack or a hole occurs in the middle of the pipe 82c, that is, downstream of the overflow prevention valve 50, and fuel leaks, Only a small amount of fuel remains and no new fuel is supplied. Therefore, the first pressure P1 that is the pressure of the fuel upstream of the overflow prevention valve 50 rapidly decreases as the second pressure P2 that is the pressure of the fuel downstream of the overflow prevention valve 50 decreases.
Therefore, since the differential pressure between the first pressure P1 and the second pressure P2 does not increase so much, the overflow prevention valve 50 does not operate. On the other hand, the feed pump 15 is also stopped along with the stop of the engine 2, but the fuel continues to flow slightly from the feed pump 15 to the pipe 82 even in the stopped state. Therefore, the leakage of fuel from the damaged part continues in the pipe 82, and the overflow prevention valve 50 needs to be closed.

Here, since the first pressure P1 and the fourth pressure P4 are in communication with each other, the fourth pressure P4 similarly decreases as the first pressure P1 rapidly decreases, but the fuel pressure in the fuel tank 4 A certain third pressure P3 does not change much. For this reason, the third pressure P3 becomes higher than the reference pressure Pb than the fourth pressure P4 (P3-P4 ≧ Pb), the overflow prevention assist valve 54 is opened, and the fuel in the fuel tank 4 is transferred to the bypass path 82d. To the downstream, that is, to the feed pump side piping 82a.
Therefore, although the first pressure P1 rises rapidly, the second pressure P2, which is downstream from the overflow prevention valve 50, does not rise due to the effect of fuel leakage in the pipe 82c downstream from the overflow prevention valve 50. The difference between the first pressure P1 and the second pressure P2 increases. Therefore, the first pressure P1 becomes higher than the reference pressure Pa than the second pressure P2 (P1-P2 ≧ Pa), the overflow prevention valve 50 is activated and closed, and the supply of fuel downstream from it is stopped. .

  That is, the overflow prevention assist valve 54 changes the first pressure P1 that is the pressure of the fuel upstream from the overflow prevention valve 50 to the second pressure that is the pressure of the fuel downstream of the overflow prevention valve 50 by the flow of the fuel flowing through the bypass path 82d. The pressure is set to be higher than the reference pressure Pa by the pressure P2 (P1−P2 ≧ Pa), and the overflow prevention valve 50 is reliably operated.

  Next, the accumulator 125 includes a hollow cylindrical cylinder 145 constituting the outer wall, and both ends of the cylinder 145 are closed. An accumulator side pipe 82b is connected to one of the closed end faces, and the inside of the accumulator side pipe 82b and the inside of the cylinder 145 communicate with each other. Further, the accumulator 125 is provided with a bellows 60 formed of an elastic bellows in the shape of a hollow hollow cylinder made of metal inside the cylinder 145, and the closed end surface of the bellows 60 is connected to the accumulator side pipe 82b. It becomes the end surface 145a side of the cylinder. The bellows 60 can be expanded and contracted inside the cylinder 145, but the movable part thereof is not provided with a seal or the like, and the outer diameter of the bellows 60 is slightly smaller than the inner diameter of the cylinder 145.

The internal space of the accumulator 125 is divided into an internal space of the bellows 60 that is a space on the side where the bellows 60 is disposed and an external space of the bellows 60 that is the opposite side when viewed from the bottom plate that is the closed end face of the bellows 60. Of these, the inner space of the bellows 60 is the low pressure chamber 305, and the outer space of the bellows 60 is the high pressure chamber 325.
The bellows 60 urges a bottom plate, which is a closed end face thereof, toward the high pressure chamber 325 side. That is, the bellows 60 is elastically contracted when the pressure of the fuel in the high pressure chamber 325 increases, and expands when the pressure of the fuel in the high pressure chamber 325 decreases.

The bellows 60 has a protrusion 60 a on the outer side of the bottom plate, that is, on the side opposite to the bellows portion of the bellows 60. For this reason, when the bellows 60 is extended to some extent, the protrusion 60a comes into contact with the end surface 145a of the cylinder to prevent further movement of the bottom plate of the bellows 60, and the bottom plate of the bellows 60 is attracted to the end surface 145a of the cylinder. To prevent.
The cylinder 145 is provided with a communication hole 245 that allows the storage space 4b and the low pressure chamber 305 to communicate with each other. As the fuel flows through the communication hole 245, the pressure in the storage space 4b and the pressure in the low pressure chamber 305 are always kept the same.
An electromagnetic valve 40 is provided in the middle of the accumulator side pipe 82b, that is, downstream of the accumulator 125.

Next, the operation of the fuel supply system 105 according to Embodiment 5 of the present invention will be described with reference to FIG. FIGS. 8A to 8C are views showing the operation around the accumulator 125 in the operation of the fuel supply system 105 in FIG.
FIG. 8A shows a state where the engine 2 is in operation. The feed pump 15 supplies fuel to the injection pump 6 through the feed pump side pipe 82a and the pipe 82c, and further supplies fuel to the high pressure chamber 325 in the accumulator 125 through the feed pump side pipe 82a and the accumulator side pipe 82b. send. In addition, the electromagnetic valve 40 provided in the middle of the accumulator side piping 82b is opened. The fuel sent from the feed pump 15 to the high pressure chamber 325 is stored in the high pressure chamber 325 as it is. Furthermore, the pressure in the high pressure chamber 325 increases to the same pressure as the discharge pressure of the feed pump 15 during operation of the engine 2, for example, about 3 MPa. In this way, the bellows 60 is held in a contracted state by the pressure increase during the operation of the engine 2, and fuel is stored in the high pressure chamber 325 of the cylinder 145. In this way, the accumulator 125 accumulates pressure.
Further, the pressure difference between the high pressure chamber 325 and the low pressure chamber 305 causes the bottom plate of the bellows 60 to overcome the urging force of the bellows 60, causing the bellows 60 to contract, and the volume of the high pressure chamber 325 to increase.

FIG. 8B shows a state where the engine 2 is stopped. When an instruction to stop the engine 2 during operation is given, the solenoid valve 40 is closed and the engine 2 is stopped. When the engine 2 stops, the feed pump 15 also stops. Therefore, the pressure in the high pressure chamber 325 is maintained.
As described above, the bellows 60 is contracted by the pressure of the fuel supplied from the feed pump 15 and the electromagnetic valve 40 is closed, so that the fuel whose pressure is higher than the fuel in the fuel tank 4 is held in the cylinder 145.

FIG. 8C shows a state when the engine 2 is started. When the engine 2 is started, first, the electromagnetic valve 40 is driven by a battery and opened. As a result, the fuel in the high pressure chamber 325 can flow out through the accumulator side pipe 82b, and flows out as the bellows 60 expands and its bottom plate slides toward the high pressure chamber 325 side.
Since the subsequent operation is the same as that of the first embodiment, description thereof is omitted. In addition, after the start of the engine 2 is completed, in the fifth embodiment, the electromagnetic valve 40 remains open.

  As described above, the fuel supply system 105 according to the fifth embodiment includes the accumulator 125 provided inside the fuel tank 4 and the accumulator 125 and the injection pump 6 as in the first to fourth embodiments. And an electromagnetic valve 40 provided. First, when the engine 2 is stopped, the electromagnetic valve 40 is closed, so that the accumulator 125 stores and maintains a pressure equal to the discharge pressure of the feed pump 15. When the engine 2 is started, the solenoid valve 40 is opened, so that fuel having a pressure equal to the discharge pressure of the feed pump 15 stored in the accumulator 125 is supplied to the injection pump 6. As a result, the fuel supply system 105 can perform sufficient pressure increase such that the fuel is not vaporized during the suction process of the injection pump 6, for example, about 3 MPa.

Further, the fuel supply system 105 according to the fifth embodiment can obtain the same effects as those of the first and second embodiments.
Further, in the fifth embodiment, a metal bellows 60 is employed as a positive displacement compression mechanism in the accumulator 125 instead of the piston 20 employed in the first and second embodiments. Unlike the piston 20, the metal bellows 60 does not need to have a seal on its movable part, and can improve durability.
Further, in the fuel supply system 105 according to the fifth embodiment, the overflow prevention valve 50 can be operated by the overflow prevention assist valve 54 when the engine 2 is stopped. Therefore, when the engine 2 is stopped, the overflow prevention valve 50 can prevent the fuel from leaking downstream.

  In the fifth embodiment, the overflow prevention assist valve 54 and the bypass path 82d are provided in the feed pump 15. However, the present invention is not limited to this. The bypass path 82d only needs to communicate the storage space 4b in the fuel tank 4 with the upstream side of the overflow prevention valve 50 in the pipe 82, and further, the flow of fuel from the bypass path 82d to the overflow prevention valve 50 It is sufficient that there are no obstacles between them, and the position is not limited. Further, the overflow prevention assist valve 54 may be in the middle of the bypass path 82d. Therefore, the overflow prevention assist valve 54 may be integrated with the overflow prevention valve 50.

Embodiment 6 FIG.
Next, the configuration of a power generation system including a fuel supply system 106 according to Embodiment 6 of the present invention will be described with reference to FIG.
The fuel supply system 106 according to Embodiment 6 of the present invention does not include the overflow prevention assist valve 54 and the bypass path 82d provided in the feed pump 15 in Embodiment 5. Furthermore, a liquid accumulator 70 for storing fuel is provided in the middle of the accumulator side pipe 82b.
In the sixth embodiment, the same reference numerals as those in FIGS. 1 to 8 are the same or similar components, and thus detailed description thereof is omitted.

  The fuel supply system 106 according to the sixth embodiment has a configuration excluding the overflow prevention assist valve 54 and the bypass path 82d in the feed pump 15 according to the fifth embodiment, in the middle of the accumulator side pipe 82b, that is, the solenoid valve 40. A reservoir 70 is provided downstream. Therefore, description of the same components as those in the fifth embodiment is omitted.

Here, the liquid reservoir 70 will be described. The accumulator 70 has the same effect as the overflow prevention assist valve 54 in the fifth embodiment, and assists the operation of the overflow prevention valve 50 by supplying fuel to the overflow prevention valve 50. is there. For example, as will be described later, when the engine 2 is stopped, the electromagnetic valve 40 provided on the downstream side of the accumulator 125 is closed. Therefore, only the fuel for the volume of this pipe remains in the feed pump side pipe 82a and the pipe 82c, and no new fuel is supplied.
In the sixth embodiment, a liquid accumulator 70 is provided in the middle of the accumulator side pipe 82b, that is, downstream of the electromagnetic valve 40, and a feed pump is provided in the liquid accumulator 70 during operation of the engine 2. The fuel supplied from 10 is stored. Since the stored fuel is prevented from flowing back to the feed pump 10 by the check valve 18 provided in the feed pump side pipe 82a downstream of the feed pump 10, the pressure can be maintained.

Accordingly, in the pipe 82 c, when a fuel leak occurs due to a crack, a hole, or the like downstream of the overflow prevention valve 50, the fuel flows out of the reservoir 70 and is supplied to the overflow prevention valve 50. Is done. Therefore, as in the case of the overflow prevention assist valve 54, the pressure P1 of the fuel upstream of the overflow prevention valve 50 rises all at once, and the pressure P1 of the fuel upstream of the overflow prevention valve 50 and the downstream fuel The difference in pressure with respect to the pressure P2 increases to reach the reference pressure Pa or higher (P1−P2 ≧ Pa). Accordingly, the overflow prevention valve 50 is activated and closed, and the supply to the downstream side of the overflow prevention valve 50 is stopped.
In other words, the reservoir 70 causes the pressure P1 of the fuel upstream of the overflow prevention valve 50 to be higher than the reference pressure Pa or higher than the pressure P2 of the downstream fuel by the outflow of the stored fuel (P1-P2 ≧). Pa) for reliably operating the overflow prevention valve 50.

Next, the operation of the fuel supply system 106 according to Embodiment 6 of the present invention will be described with reference to FIG. The operation around the accumulator 125 along with the operation of the fuel supply system 106 is the same as that shown in FIG.
During operation of the engine 2, the electromagnetic valve 40 is opened.
Further, the fuel sent from the feed pump 10 through the feed pump side pipe 82 a and the accumulator side pipe 82 b to the high pressure chamber 325 in the accumulator 70 and the accumulator 125 is stored in the accumulator 70 and the high pressure chamber 325 as it is. The Further, the pressure in the reservoir 70 and the high pressure chamber 325 increases to the same pressure as the discharge pressure of the feed pump 10 during operation of the engine 2, for example, about 3 MPa.

When the engine 2 is stopped, if an instruction to stop the engine 2 during operation is given, the solenoid valve 40 is closed and the engine 2 is stopped. When the engine 2 stops, the feed pump 10 also stops. Here, since the electromagnetic valve 40 is closed, the pressure in the high pressure chamber 325 is maintained.
When the engine 2 is started, the electromagnetic valve 40 is driven by the battery and opens. Therefore, the fuel in the high-pressure chamber 325 and the reservoir 70 can flow out through the accumulator-side pipe 82b, and flows out as the bellows 60 expands and the bottom plate slides toward the high-pressure chamber 325.
Since the subsequent operation is the same as that of the first embodiment, the description thereof is omitted. In addition, after the start of the engine 2 is completed, the electromagnetic valve 40 remains open in the sixth embodiment.

  As described above, the fuel supply system 106 according to the sixth embodiment includes the accumulator 125 provided inside the fuel tank 4 and the accumulator 125 and the injection pump 6 as in the first to fifth embodiments. And an electromagnetic valve 40 provided. First, when the engine 2 is stopped, the electromagnetic valve 40 is closed, so that the accumulator 125 stores and maintains a pressure equal to the discharge pressure of the feed pump 10. When the engine 2 is started, the solenoid valve 40 is opened, so that fuel having a pressure equal to the discharge pressure of the feed pump 10 stored in the accumulator 125 is supplied to the injection pump 6. As a result, the fuel supply system 106 can perform sufficient pressure increase such that the fuel is not vaporized during the suction process of the injection pump 6, for example, about 3 MPa.

Further, the fuel supply system 106 according to the sixth embodiment can obtain the same effects as those of the first, second and fifth embodiments.
Further, in the fuel supply system 106 according to the sixth embodiment, the overflow prevention valve 50 can be operated by the liquid accumulator 70 when the engine 2 is stopped. Therefore, when the engine 2 is stopped, the overflow prevention valve 50 can prevent the fuel from leaking downstream.

  In the sixth embodiment, the liquid reservoir 70 is provided in the middle of the accumulator side pipe 82b, but is not limited thereto. The accumulator 70 is upstream of the overflow prevention valve 50 in the pipe 82, and the fuel from the accumulator 70 to the overflow prevention valve 50 is interposed between the accumulator 70 and the overflow prevention valve 50. The position is not limited as long as there is no thing blocking the flow. Therefore, the accumulator 70 may be integrated with the accumulator 125 and the electromagnetic valve 40.

In the first to sixth embodiments, the accumulator is a piston-type device including the piston 20 therein or a bellows-type device including the bellows 60. However, the present invention is not limited thereto, and any other method may be used as long as it is a displacement type compression mechanism. For example, a scroll type or a vane type may be used.
In the first to sixth embodiments, the accumulator is provided in the fuel tank 4 integrally with the feed pump. However, the accumulator may be separated from the feed pump. It may be provided integrally with the outer wall 4a.
Moreover, the injection pump 6 in Embodiment 1-6 will not be limited if it supplies a fuel to the internal combustion engine 2, and includes the high-pressure supply pump etc. which are used for a common rail.
Furthermore, the fuel supply system according to Embodiments 1 to 6 is applied to an internal combustion engine mounted on a vehicle. The fuel supply system according to the present invention is not limited to application to a vehicle, but can also be applied to an internal combustion engine used in a cogeneration system or the like.

It is a figure which shows the structure of the fuel supply system which concerns on Embodiment 1 of this invention. It is a figure explaining the flow of operation | movement of the fuel supply system of FIG. It is a figure which shows the structure of the fuel supply system which concerns on Embodiment 2 of this invention. It is a figure explaining the flow of operation | movement of the fuel supply system of FIG. It is a figure which shows the structure of the fuel supply system which concerns on Embodiment 3 of this invention. It is a figure which shows the structure of the fuel supply system which concerns on Embodiment 4 of this invention. It is a figure which shows the structure of the fuel supply system which concerns on Embodiment 5 of this invention. It is a figure explaining the flow of operation | movement of the fuel supply system of FIG. It is a figure which shows the structure of the fuel supply system which concerns on Embodiment 6 of this invention.

Explanation of symbols

  2 engine (internal combustion engine), 4 fuel tank, 10, 15 feed pump (pump), 12, 122, 125 accumulator (accumulation means), 14, 142, 145 cylinder, 18 check valve, 20 piston, 22 spring, 40 , 51 Solenoid valve (open / close valve), 50 Overflow prevention valve, 52 Pressure sensor, 53 Engine speed sensor, 54 Overflow prevention assist valve (auxiliary valve), 60 Bellows, 70 Accumulator, 82d Bypass path, 100 , 102, 103, 104, 105, 106 Fuel supply system.

Claims (15)

A fuel tank,
A fuel supply system comprising a pump provided inside the fuel tank and configured to supply fuel from the fuel tank to an injection pump of an external internal combustion engine;
Pressure accumulating means provided inside the fuel tank, the accumulating means supplying the fuel supplied from the pump to the injection pump of the internal combustion engine;
A first path which is a path of the fuel supplied from the pressure accumulating means to the injection pump of the internal combustion engine;
An on-off valve provided downstream of the pressure accumulating means and opening and closing the first path;
The fuel supply system according to claim 1, wherein the on-off valve is closed when the operation of the internal combustion engine is stopped, and is opened when the internal combustion engine is started.   The fuel supply system according to claim 1, wherein the on-off valve is closed during operation of the internal combustion engine.   The fuel supply system according to claim 1, wherein the on-off valve is open during operation of the internal combustion engine.   The fuel supply system according to any one of claims 1 to 3, wherein the on-off valve is provided inside the fuel tank or integrally with the fuel tank.   The fuel supply system according to claim 1, wherein the on-off valve is provided outside the fuel tank.   The fuel supply system according to any one of claims 1 to 5, wherein the pressure accumulating means includes a positive displacement compression mechanism. The pressure accumulating means is
A cylinder,
A piston slidably provided inside the cylinder;
A spring for biasing the piston in one direction,
Due to the pressure of the fuel supplied from the pump, the piston slides against the urging force, and the on-off valve closes, so that fuel having a higher pressure than the fuel in the fuel tank is in the cylinder. The fuel supply system according to any one of claims 1 to 6, wherein the fuel supply system is held in the tank. The pressure accumulating means is
A cylinder,
A bellows provided inside the cylinder so as to be extendable and contractible,
The bellows is elastically contracted by the pressure of the fuel supplied from the pump, and the on-off valve is closed, whereby fuel having a pressure higher than that of the fuel in the fuel tank is held in the cylinder. Item 7. The fuel supply system according to any one of Items 1 to 6.   The fuel supply system according to claim 1, further comprising a second path different from the first path for supplying fuel from the pump to the internal combustion engine. The pressure accumulating means or provided upstream of the first path and in the middle of the second path,
The fuel supply system according to any one of claims 1 to 9, further comprising a check valve for preventing the fuel from flowing from the pressure accumulating means to the pump. An overflow prevention valve is provided downstream of the pressure accumulating means,
The fuel supply system according to any one of claims 1 to 10, wherein the overflow prevention valve operates based on a pressure difference between the upstream and downstream fuels. An overflow prevention valve is provided downstream of the pressure accumulating means,
Furthermore, a pressure sensor is provided downstream of the overflow prevention valve,
The fuel supply system according to any one of claims 1 to 10, wherein the overflow prevention valve operates based on a pressure detected by the pressure sensor. An overflow prevention valve is provided downstream of the pressure accumulating means,
The fuel supply system according to any one of claims 1 to 10, wherein the overflow prevention valve operates based on an engine speed detected by an engine speed sensor provided in the internal combustion engine. The fuel tank;
A bypass path upstream of the overflow prevention valve and communicating with the middle of the first path or the middle of the second path;
The bypass path includes an auxiliary valve,
The fuel supply system according to any one of claims 1 to 13, wherein the auxiliary valve operates based on a pressure difference between the upstream and downstream fuels to assist the operation of the overflow prevention valve. The fuel supply as described in any one of Claims 1-14 provided with the liquid storage which stores the said fuel in the middle of the said 1st path | route or the said 2nd path | route upstream from the said overflow prevention valve. system.

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