JP2010163984A - Liquefied gas fuel supply device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquefied gas fuel supply device for an internal combustion engine equipped with an opening and closing valve device, capable of suppressing increase in costs without requiring direct operation. <P>SOLUTION: The liquefied gas fuel supply device includes a purging means for recovering liquefied gas fuel in a common rail into a fuel tank while introducing the gas component of liquefied gas fuel to the common rail after stopping the internal combustion engine. The purging means includes at least either one of the purging passage and the gas phase introduction passage connected to the common rail; and the opening and closing valve device disposed on at least either one of the purging passage and the gas phase introduction passage, having a pressure receiving part receiving a fuel pressure sent from a feed pump to a high pressure pump, and closing a valve when the fuel pressure is equal to or more than a prescribed value and opening the valve when the fuel pressure is less than the prescribed value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquefied gas fuel supply apparatus for an internal combustion engine, and more particularly to a liquefied gas fuel supply apparatus for an internal combustion engine provided with a purge means for recovering liquefied gas fuel in a common rail when the internal combustion engine is stopped.

  In recent years, use of DME (dimethyl ether) with clean exhaust gas as an alternative fuel instead of diesel oil has been studied as a countermeasure against air pollution by diesel engines. This DME fuel is a liquefied gas fuel, unlike conventional diesel fuel. That is, the boiling point is lower than that of light oil, and light oil is liquid at normal temperature under atmospheric pressure, whereas DME has a property of becoming a gas at normal temperature.

  Therefore, in a diesel engine using DME fuel, if DME fuel remains in the injection system after the engine is stopped, the DME fuel leaks into the engine cylinder from the injector nozzle hole and vaporizes, and fills the cylinder. As a result, when the engine is started next, abnormal combustion such as knocking occurs, and the engine cannot be started normally, and there is a risk of generating large vibrations and noise. Therefore, when DME fuel is used as an alternative fuel, it is necessary to perform a purge process for removing the DME fuel remaining in the injection system after the engine is stopped.

  Therefore, the applicant of the present application has heretofore used a pressure accumulation type fuel supply device including a common rail connected to a plurality of fuel injection valves as a fuel supply device for injecting and supplying liquefied gas fuel to an internal combustion engine. A fuel supply apparatus has been proposed that is configured to recover the liquefied gas fuel in the common rail when the internal combustion engine is stopped.

  More specifically, the liquefied gas fuel in the fuel tank is sent to a high-pressure pump by a feed pump, and the liquefied gas fuel is increased in pressure by the high-pressure pump and is pumped to a common rail to which a fuel injection portion of an internal combustion engine is connected. In the liquefied gas fuel supply device for supplying liquefied gas fuel from the section to the internal combustion engine, the feed pump and the high pressure pump are connected by a low pressure fuel supply passage, and the low pressure fuel supply passage is provided with a first opening / closing means, The gas phase portion of the fuel tank and the common rail are connected by a gas phase introduction passage, the gas phase introduction passage is provided with a second opening / closing means, and a fuel supply passage on the high-pressure pump side with respect to the first opening / closing means. The purge is connected to the common rail by a purge passage, and the purge passage is provided with a third opening / closing means, and the gaseous component of the liquefied gas fuel from the gas phase introduction passage. Liquid purge means for recovering the liquefied gas fuel in the high pressure pump, common rail and fuel injection section into the fuel tank while being introduced, and liquefied gas remaining in the high pressure pump, common rail and fuel injection section after the operation of the liquid purge means There has been disclosed a liquefied gas fuel supply device for an internal combustion engine comprising vaporization purge means for vaporizing and collecting the fuel (see Patent Document 1).

JP 2008-286121 A (paragraphs [0022] to [0028])

  In the liquefied gas fuel supply apparatus for an internal combustion engine described in Patent Document 1, second and third opening / closing means provided in a gas phase introduction passage and a purge passage connected to a common rail are provided. These second and third opening / closing means are closed when the internal combustion engine is in operation, and need to be opened when recovering the liquefied gas fuel in the common rail after the internal combustion engine is stopped. However, in an opening / closing means that requires a direct opening / closing operation such as electrical control, not only the cost of the opening / closing means itself but also the cost of the control device is increased, so an opening / closing means that does not require any operation is desirable.

  Accordingly, the inventors of the present invention have made diligent efforts and provided in the gas phase introduction passage or the purge passage in the liquefied gas fuel device provided with at least one of the gas phase introduction passage and the purge passage connected to the common rail. The inventors have found that such a problem can be solved by using an opening / closing valve device having a predetermined configuration as the opening / closing means, and have completed the present invention. That is, an object of the present invention is to provide a liquefied gas fuel supply device for an internal combustion engine including an on-off valve device that does not require a direct operation and that suppresses an increase in cost.

  According to the present invention, the liquefied gas fuel in the fuel tank is sent to the high pressure pump by the feed pump, and the liquefied gas fuel is pressurized by the high pressure pump to the common rail to which the fuel injection portion of the internal combustion engine is connected. In the liquefied gas fuel supply device that supplies liquefied gas fuel from the section to the internal combustion engine, the liquefied gas fuel in the common rail is recovered in the fuel tank while the gaseous component of the liquefied gas fuel is introduced into the common rail after the internal combustion engine is stopped Purge means, and the purge means includes a purge passage and / or a gas-phase introduction passage connected to the common rail, and is provided in the purge passage and / or the gas-phase introduction passage. When there is a pressure-receiving part that receives the fuel pressure sent from the pump to the high-pressure pump, and the fuel pressure is above the specified value While closed, the liquefied gas fuel supply device for an internal combustion engine fuel pressure, characterized in that it comprises an opening and closing valve device opens when less than a predetermined value is provided, it is possible to solve the problems described above.

  Further, in configuring the liquefied gas fuel supply device for an internal combustion engine of the present invention, the on-off valve device receives the first port connected to the common rail and a part of the liquefied gas fuel sent from the feed pump to the high pressure pump. A cylinder body having a second port and a third port connected to a suction part or a gas phase introduction part for liquefied gas fuel, and a first port having a pressure receiving part for receiving the fuel pressure flowing in from the second port A piston valve member housed in the cylinder body so that the first and third ports can be communicated and blocked, and a piston valve member that allows the first and third ports to communicate and block according to the fuel pressure. And a spring member for biasing.

  Further, in configuring the liquefied gas fuel supply device of the internal combustion engine of the present invention, the on-off valve device includes a feed pump, a pressure regulating valve that regulates the pressure of the liquefied gas fuel fed by the feed pump and sent to the high pressure pump, Is preferably connected to a low pressure fuel supply passage between the two.

  According to the liquefied gas fuel supply device for an internal combustion engine of the present invention, the pressure receiving portion that receives the fuel pressure sent from the feed pump to the high pressure pump as the on-off valve device provided in the purge passage and the gas phase introduction passage connected to the common rail. In addition, since an on-off valve device that opens and closes according to the fuel pressure is employed, direct operation of the on-off valve device becomes unnecessary. As a result, an increase in the cost of the on-off valve device and hence the liquefied gas fuel supply device can be suppressed.

  In the liquefied gas fuel supply apparatus for an internal combustion engine according to the present invention, the on-off valve device includes a predetermined cylinder body, a piston valve member, and a spring member. Even when the third opening / closing means is exposed to the high pressure in the common rail, a highly reliable on-off valve device capable of withstanding the high pressure is provided.

  In the liquefied gas fuel supply device for an internal combustion engine of the present invention, the on-off valve device is connected to a predetermined position of the low-pressure fuel supply passage, so that the on-off valve device is opened and closed by operating or stopping the feed pump. The on-off valve device can be opened and closed in response to the on / off operation of the liquefied gas fuel supply device.

It is a figure which shows the structural example of the liquefied gas fuel supply apparatus of the internal combustion engine of this embodiment. It is a figure for demonstrating an example of a structure of an on-off valve apparatus. It is a figure which shows the state of the liquefied gas fuel supply apparatus at the time of a stop of an internal combustion engine. It is a figure which shows the state of the liquefied gas fuel supply apparatus at the time of fuel filling. It is a figure which shows the state of the liquefied gas fuel supply apparatus at the time of operation | movement of an internal combustion engine. It is a figure which shows the state of the liquefied gas fuel supply apparatus at the time of a liquid purge. It is a figure which shows the state of the liquefied gas fuel supply apparatus at the time of vaporization purge.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments relating to a liquefied gas fuel supply device for an internal combustion engine according to the present invention will be specifically described below with reference to the drawings. However, this embodiment shows one aspect of the present invention, and does not limit the present invention, and can be arbitrarily changed within the scope of the present invention. In addition, what attached | subjected the same code | symbol in each figure has shown the same member, and description is abbreviate | omitted suitably.

1. 1 is a schematic diagram showing the overall configuration of a liquefied gas fuel supply apparatus for an internal combustion engine according to an embodiment of the present invention. A typical example of the liquefied gas fuel is dimethyl ether (DME). In addition to this, any liquefied gas fuel that can be used as a fuel for an internal combustion engine may be used in the liquefied gas fuel supply device of the present invention. Can be used.

A liquefied gas fuel supply apparatus 100 for an internal combustion engine shown in FIG. 1 includes a fuel tank 1, an in-tank feed pump 2, a high-pressure pump 5, a common rail 10, an injector 13, a purge tank 9, and the like as main components. As prepared. Each component is connected by a fuel passage and a purge passage.
The fuel tank 1 stores liquefied gas fuel. The liquefied gas fuel is, for example, DME fuel, and the fuel tank 1 is not particularly limited as long as the liquefied gas fuel can be stored tightly.

  An in-tank feed pump 2 is disposed in the fuel tank 1, and the in-tank feed pump 2 supplies the fuel in the fuel tank 1 to the high-pressure pump 5 through the low-pressure fuel supply passage 18a. The in-tank feed pump 2 is, for example, an electric pump, and a liquefied gas fuel having a predetermined flow rate is pumped by supplying a pulse voltage. Further, a pre-filter 3 is interposed in the fuel suction port of the in-tank feed pump 2, and when foreign matters are mixed in the liquefied gas fuel in the fuel tank 1, these foreign matters are collected so as not to be sucked. The

  The low-pressure fuel supply passage 18 a that connects the fuel tank 1 and the high-pressure pump 5 is provided with a filter 4 and first opening / closing means 19. Floating matter in the liquefied gas fuel is collected by the filter 4 provided in the low-pressure fuel supply passage 18 a and does not flow into the high-pressure pump 5. The first opening / closing means 19 is, for example, an electromagnetically controlled ON / OFF valve that opens and closes the low-pressure fuel supply passage 18a.

  Further, the high-pressure pump 5 is provided with a flow control valve 8 and controls the flow rate of the low-pressure fuel supplied through the low-pressure fuel supply passage 18a and sent to the pressurizing chamber of the high-pressure pump 5 according to the required common rail pressure. To do. As this flow control valve 8, for example, an electromagnetic proportional flow control valve is used. Further, on the upstream side of the flow control valve 8, a low-pressure fuel supply passage 18 b branches from the low-pressure fuel supply passage 18 a and is connected to fuel return passages 30 a and 30 b communicating with the fuel tank 1. The fuel return passage 30b is provided with an overflow valve 14 arranged in parallel with the flow control valve 8, and is opened when the fuel flow rate sent to the flow control valve 8 is excessive, and excess fuel is supplied. Returned to the fuel tank 1. The overflow valve 14 adjusts the pressure of the low-pressure fuel sent to the pressurizing chamber of the high-pressure pump 5.

  A flow sensor 15 and a fuel cooler 16 are provided in the middle of the fuel return passage 30a. Among these, the fuel cooler 16 cools the liquefied gas fuel returned into the fuel tank 1 so that the temperature of the liquefied gas fuel is maintained below a predetermined temperature. The flow sensor 15 is used for detecting the flow rate of the liquefied gas fuel passing through the fuel return passage 30a and measuring the start timing of the internal combustion engine.

  The high pressure pump 5 pressurizes the liquefied gas fuel introduced into the pressurizing chamber with a plunger (not shown), and pumps it to the common rail 10 via a fuel discharge valve (not shown) and the high pressure fuel passages 37a and 37b. To do. The cam chamber (not shown) in which the cam for reciprocating the plunger in the high-pressure pump 5 is a dedicated lubrication system separated from the lubrication system of the internal combustion engine.

  Further, the common rail 10 shown in FIG. 1 accumulates high-pressure fuel pumped from the high-pressure pump 5 and supplies the high-pressure fuel to the plurality of injectors 13 through the high-pressure fuel passage 39 at an equal pressure. In the injector 13 as a fuel injection unit connected to the common rail 10, injection control of high-pressure fuel supplied from the common rail 10 is performed, and fuel is supplied into the cylinders of the internal combustion engine. Although the form of the injector 13 is not particularly limited, for example, a known electromagnetically controlled fuel injection valve is used. The discharged fuel used for back pressure control of the injector 13 is caused to flow through the check valve 31 to the fuel return passage 30e and returned to the fuel tank 1.

2. Purge means (1) Liquid purge means (1) -1 Overall configuration of liquid purge means The liquefied gas fuel supply device for an internal combustion engine of this embodiment is provided with a liquid purge means. The liquid purging means includes a gas phase introduction passages 20a and 20b, first purge passages 24a and 24b, a second purge passage 22 branched from the low-pressure fuel supply passage 18b, a fuel circulation passage 28, and a suction passage. And an aspirator 17 as a unit.

  Among these, the aspirator 17 is used as a suction unit for recovering the liquefied gas fuel in the common rail 10, the injector 13, and the high-pressure pump 5 to the fuel tank 1. As shown in FIG. 1, the aspirator 17 has an inlet 7a, an outlet 7b, and a suction port 7c. The inlet 7a and the outlet 7b communicate with each other in a straight line, and the suction port 7c is connected to the inlet 7a and the outlet. The first purge passage 24b is branched from the communication passage between the first purge passage 24b and the first purge passage 24b.

Further, the gas phase introduction passages 20a and 20b are disposed between the gas phase portion of the fuel tank 1 and the common rail 10, and a first on-off valve device 50a is provided in the middle. The first purge passages 24a and 24b are disposed between the aspirator 17 and the common rail 10, and a second opening / closing valve device 50b is provided in the middle.
Further, the fuel circulation passage 28 is configured as a circulation passage branched from the low-pressure fuel supply passage 18a and returned to the fuel tank 1 again, and the third opening / closing means 29 and the aspirator 17 are disposed in the middle. Further, the second purge passage 22 is disposed between the low pressure fuel supply passage 18b and the first purge passage 24b, and a second opening / closing means 23 is provided in the middle.

The first opening / closing means 19 provided in the low-pressure fuel supply passage 18a, the second opening / closing means 23 provided in the second purge passage 22, and the third opening / closing means 29 provided in the fuel circulation passage 28 are: For example, an electromagnetic control type ON-OFF valve is used.
On the other hand, the first on-off valve device 50a provided in the gas phase introduction passages 20a, 20b and the second on-off valve device 50b provided in the first purge passages 24a, 24b are connected to the low-pressure fuel supply passages 18a, 18b. It is configured as a valve device that is opened and closed according to the fuel pressure inside and does not require direct operation.

(1) -2 On-off valve device FIG. 2 is a schematic view showing an example of the configuration of the first and second on-off valve devices 50a and 50b.
The on-off valve device 50a (50b) includes a cylinder body 51 as a cylinder member provided with a cylinder 51a therein, a valve piston 53 as a piston valve member that can move in the cylinder 51a of the cylinder body 51 in the axial direction, A coil spring 55 is provided as a spring member for biasing the valve piston 53, and a stopper 57 for defining the maximum movement amount of the valve piston 53.

  A fuel gallery 51b is formed on a part of the inner peripheral surface of the cylinder 51a of the cylinder body 51, and a first port 61 is provided in the fuel gallery 51b. Further, a second port 63 and a third port 65 are provided at both ends of the cylinder body 51 in the axial direction of the cylinder 51a. Of the space in the cylinder 51 a of the cylinder body 51, a space defined by the valve piston 53 and opened by the second port 63 is configured as the pressure chamber 52.

In the first on-off valve device 50a, the gas phase introduction passage 20a communicating with the common rail 10 is connected to the first port 61 of the cylinder body 51, and the low pressure fuel supply passage on the upstream side of the overflow valve 14 is connected to the second port 63. A low-pressure introduction passage 25 a communicating with 18 b is connected, and a gas phase introduction passage 20 b communicating with the gas phase portion of the fuel tank 1 is connected to the third port 65.
In the second on-off valve device 50b, the first purge passage 24a communicating with the common rail 10 is connected to the first port 61 of the cylinder body 51, and the upstream side of the overflow valve 14 is connected to the second port 63. A low-pressure introduction passage 25 b communicating with the low-pressure fuel supply passage 18 b is connected, and a first purge passage 24 b communicating with the suction port 7 c of the aspirator 17 is connected to the third port 65.

  The valve piston 53 held in the cylinder body 51 so as to be movable in the axial direction faces the inner peripheral surface of the cylinder 51a, communicates with the radial passage 53a capable of communicating with the fuel gallery 51b, and the radial passage 53a. And an axial passage 53b opened at the end on the side where the port 65 is formed. The end face of the valve piston 53 where the axial passage 53b is not opened, that is, the end face facing the pressure chamber 52 is configured as a pressure receiving face 53c that receives the pressure of the low pressure fuel.

The coil spring 55 in the cylinder body 51 is in contact with both ends of the end of the cylinder body 51 in which the third port 65 is formed and the valve piston 53, so that the valve piston 53 is connected to the cylinder body in which the second port 63 is formed. It biases toward the end side of 51.
The stopper 57 in the cylinder body 51 is fixed to the end portion where the third port 65 is formed, one end is opened in the cylinder 51a of the valve piston 53, and the other end can communicate with the third port 65. An axial passage 57a is provided.

  In the first and second on-off valve devices 50 a and 50 b configured as described above, the low-pressure fuel flows into the pressure chamber 52 via the second port 63, and the pressure in the pressure chamber 52 is applied to the coil spring 55. In a state exceeding the force, the valve piston 53 moves toward the end where the third port 65 is formed, and the communication between the radial passage 53a of the valve piston 53 and the fuel gallery 51b of the cylinder body 51 is blocked.

  On the other hand, the first and second on-off valve devices 50a and 50b are configured such that the valve piston 53 is on the end side where the second port 63 is formed in a state where the pressure in the pressure chamber 52 is lower than the urging force of the coil spring 55. The radial passage 53a of the valve piston 53 and the fuel gallery 51b of the cylinder body 51 communicate with each other. Then, in the first on-off valve device 50a, the common rail 10 and the gas phase portion in the fuel tank 1 are in communication with each other, and in the second on-off valve device 50b, the common rail 10 and the aspirator 17 are in communication with each other. Become.

  In the liquefied gas fuel supply device 100 of the present embodiment, so-called spool valve structures are employed as the first and second on-off valve devices 50a and 50b, so even if the pressure in the common rail 10 increases. The high pressure acts on the outer peripheral surface of the valve piston 53 via the fuel gallery 51 b of the cylinder body 51. Therefore, since the action of a force that moves the valve piston 53 in the axial direction does not occur, the durability of the on-off valve device is ensured and the reliability is improved.

(1) -3 Liquid Purging Method In the liquid purging means provided in the liquefied gas fuel supply apparatus 100 of the present embodiment, the first opening / closing means 19 provided in the low-pressure fuel supply passage 18a and While closing the fourth opening / closing means 27 provided in the third purge passage 26, the second opening / closing means 23 provided in the second purge passage 22 and the third opening means provided in the fuel circulation passage 28 are provided. Opening / closing means 29 is opened. When the in-tank feed pump 2 is driven in this state, the low-pressure fuel in the fuel tank 1 circulates in the fuel circulation passage 28.

  When the low-pressure fuel is not supplied to the low-pressure fuel supply passages 18a and 18b and the pressure in the pressure chamber 52 of the second on-off valve device 50b provided in the first purge passages 24a and 24b decreases, direct operation is performed. Even if not, the second on-off valve device 50 b is opened, and the injector 13 and the common rail 10 communicate with the aspirator 17. Then, the liquefied gas fuel in the injector 13 and the common rail 10 is sucked through the first purge passages 24a and 24b by the suction differential pressure generated when the fuel passes through the aspirator 17.

  At this time, the pressure in the pressure chamber 52 of the first on-off valve device 50a provided in the gas-phase introduction passages 20a and 20b is also reduced, and the first on-off valve device 50a can be operated without direct operation. be opened. Therefore, as the liquefied gas fuel in the common rail 10 is sucked by the aspirator 17, the gas phase is sucked into the common rail 10 via the gas phase introduction passages 20a and 20b. Therefore, the liquefied gas fuel in the injector 13 and the common rail 10 is recovered in the fuel tank 1 while being replaced by the gas phase portion introduced into the common rail 10 through the gas phase introduction passages 20a and 20b. The liquefied gas fuel in the high-pressure pump 5 is also sucked through the second purge passage 22 and collected in the fuel tank 1 by the suction differential pressure generated when the fuel passes through the aspirator 17. .

  In the example of the present embodiment, the aspirator 17 is used as a means for sucking the liquefied gas fuel, but other suction means may be used. When using suction means other than an aspirator, the fuel circulation passage may be omitted.

(2) Vaporization purge means (2) -1 Overall configuration of vaporization purge means The liquefied gas fuel supply device 100 for an internal combustion engine of the present embodiment is provided with a vaporization purge means. This vaporizing purge means includes a third purge passage (vaporization purge passage) 26 branched from the low-pressure fuel supply passage 18 b and a purge tank (low-pressure tank) 9. The third purge passage 26 is disposed between the high-pressure pump 5 and the purge tank 9 and is provided with a fourth opening / closing means 27 on the way. For the fourth opening / closing means 27, for example, an electromagnetically controlled ON-OFF valve is used.

  This vaporizing purge means vaporizes and recovers the liquefied gas fuel remaining in the high-pressure pump 5 communicating with the third purge passage 26. A known purge tank 9 is used. However, in the liquefied gas fuel supply apparatus 100 of the present embodiment, vaporization purge is performed after most of the liquefied gas fuel is recovered by the liquid purging means. Even a small purge tank can be used.

(2) -2 Vaporization purge method In the vaporization purge means of the liquefied gas fuel supply apparatus 100 of the present embodiment, when the vaporization purge is executed, the first opening / closing means 19 disposed in the low-pressure fuel supply passage 18 and the second The second opening / closing means 23 disposed in the purge passage 22 is closed, while the fourth opening / closing means 27 disposed in the third purge passage 26 is opened. Then, the high pressure pump 5 communicates with the third purge passage 26. As a result, the high pressure pump 5 is in communication with the decompressed purge tank 9, and the liquefied gas fuel remaining in the high pressure pump 5 is vaporized and collected in the purge tank 9.
The fuel recovered by the vaporization purge is sent to the reliquefaction compressor 6 through the check valve 33 after the next start of the internal combustion engine, reliquefied, and then recovered to the fuel tank 1.

3. Operation of Liquefied Gas Fuel Supply Device Next, the operation of the liquefied gas fuel supply device 100 of the internal combustion engine of the present embodiment described so far will be described with reference to FIGS. 3 to 7, the low pressure fuel passages 18a and 18b, the gas phase introduction passages 20a and 20b, the first purge passages 24a and 24b, the second purge passage 22 and the third purge passage 26. Of the low-pressure introduction passages 25a and 25b, the fuel circulation passage 28, the fuel return passages 30a to 30e, and the high-pressure fuel passages 37a, 37b, and 39, the passage of the liquefied gas fuel or the vapor phase is shown by a solid line and does not circulate The state path is indicated by a dashed line.

(1) When the internal combustion engine is stopped First, a state when the internal combustion engine is stopped is shown in FIG. When the internal combustion engine is stopped, all of the first to fourth opening / closing means 19, 23, 27, and 29 are closed. Further, since the in-tank feed pump 2 is not driven and the pressure in the pressure chamber 52 of the first and second on-off valve devices 50a, 50b does not increase, the first and second on-off valve devices 50a, 50b Will be open.

(2) At the time of fuel filling before starting Next, FIG. 4 shows a state at the time of fuel filling before starting the internal combustion engine. At the time of fuel filling, a second purge means branching from the second open / close means 23 provided in the second purge passage 22 disposed between the high pressure pump 5 and the aspirator 17 and the low pressure fuel supply passage 18b. The fourth opening / closing means 27 provided in the passage 26 and the third opening / closing means 29 provided in the fuel circulation passage 28 are closed. On the other hand, the first opening / closing means 19 provided in the low-pressure fuel supply passage 18a disposed between the fuel tank 1 and the high-pressure pump 5 is opened.

  When the in-tank feed pump 2 is driven in this state, the liquefied gas fuel in the fuel tank 1 flows into the high-pressure pump 5 side via the low-pressure fuel supply passage 18a. At this time, the low-pressure fuel sent by the in-tank feed pump 2 enters the pressure chambers 52 of the first and second on-off valve devices 50a and 50b via the low-pressure introduction passages 25a and 25b branched from the low-pressure fuel supply passage 18b. Also flows in. As a result, the valve piston 53 of the first and second on-off valve devices 50a and 50b moves and the first and second on-off valve devices 50a and 50b are closed without direct operation. Become. When the high-pressure pump 5 is filled with liquefied gas fuel, the pressure in the low-pressure fuel supply passages 18a and 18b gradually rises, and the overflow valve 14 is opened when the predetermined pressure value is exceeded. The fuel is returned to the fuel tank 1 through the return passages 30a and 30b.

  Thereafter, when the detected value of the flow sensor 15 provided in the fuel return passage 30a exceeds a predetermined threshold value, it is determined that the high-pressure pump 5 is reliably filled with the liquefied gas fuel, and the internal combustion engine is started. Allowed.

(3) During Operation of Internal Combustion Engine Next, a state during operation of the internal combustion engine is shown in FIG. During operation of the internal combustion engine, the first opening / closing means 19 is continuously opened, and the first and second opening / closing valve devices 50a, 50b and the second to fourth opening / closing means 23, 27, 29 are continuously closed.

  In this state, the liquefied gas fuel in the fuel tank 1 flows into the pressurizing chamber of the high pressure pump 5 while the flow rate is controlled by the flow rate control valve 8, is pressurized by the plunger, and is discharged from the fuel discharge valve and the high pressure fuel passage 37a. , 37b and fed to the common rail 10 by pressure. The fuel pumped to the common rail 10 is supplied at a uniform pressure to the plurality of injectors 13 connected to the common rail 10 via the high-pressure fuel passage 39, and is supplied into the cylinder of the internal combustion engine by the injection control of the injector 13. Is done. At this time, the pressure in the common rail 10 increases, but the first and second on-off valve devices 50a and 50b employed in the present embodiment have a highly reliable structure that can withstand high pressures. High-pressure fuel does not flow to the gas phase introduction passage 20b or the first purge passage 24b.

  During operation of the internal combustion engine, fuel that overflows from the high-pressure pump 5, fuel that is discharged from the pressure control valve 12 of the common rail 10, fuel that is used for back pressure control of the injector 13 and that is discharged through the check valve 31 Is returned to the fuel tank via the fuel return passage.

  Further, when the internal combustion engine is started and the driving of the high-pressure pump 5 is started, the reliquefaction compressor 6 is also operated. Therefore, the gas fuel recovered in the purge tank 9 is recirculated through the check valve 33. 6 is re-liquefied and returned to the fuel tank 1.

(4) At the time of liquid purge Next, the state in which the internal combustion engine is stopped and the liquid purge is performed is shown in FIG. During the liquid purge, the fourth opening / closing means 27 that was closed during operation of the internal combustion engine is continuously closed. On the other hand, the first opening / closing means 19 that was opened during the operation of the internal combustion engine is closed, and the second and third opening / closing means 23 and 29 that were closed during the operation of the internal combustion engine are opened. Further, since the supply of the low-pressure fuel to the low-pressure fuel supply passage 18b and the low-pressure introduction passages 25a, 25b is stopped by closing the first opening / closing means 19, the first and second on-off valve devices 50a, 50b When the pressure in the pressure chamber 52 decreases and the valve piston 53 moves, the first and second on-off valve devices 50a and 50b are opened.

  When the liquefied gas fuel is sent by the in-tank feed pump 2 in this state, the liquefied gas fuel flows through the fuel circulation passage 28 and flows into the aspirator 17. When the liquefied gas fuel passes through the aspirator 17, the liquefied gas fuel in the first purge passages 24a and 24b and the second purge passage 22 is sucked by the generated suction differential pressure. Then, since the first on-off valve device 50a disposed in the gas phase introduction passage 20 connected to the common rail 10 is opened, the liquefied gas fuel in the common rail 10 and the injector 13 is replaced by the gas phase, so that the fuel It is collected in the tank 1.

The liquefied gas fuel in the high-pressure pump 5 is also sucked by the aspirator 17 through the second purge passage 22 and collected in the fuel tank 1.
At the end of the liquid purging, most of the liquefied gas fuel in the high-pressure pump 5, the common rail 10, and the injector 13 is recovered.

(5) At the time of vaporization purge Next, the state in which vaporization purge is performed is shown in FIG. During the vaporization purge, the first opening / closing means 19 that was closed during the liquid purge is continuously closed, and the first and second open / close valve devices 50a and 50b that were opened during the liquid purge are continuously opened. On the other hand, the second and third opening / closing means 23 and 29 opened during the liquid purge are closed, and the fourth opening / closing means 27 closed during the liquid purge is opened. Further, the driving of the in-tank feed pump 2 is stopped.

In this state, the high-pressure pump 5 is in communication with the pressure-reduced purge tank 9, so that a small amount of liquefied gas fuel remaining inside is vaporized and purged via the third purge passage 26. It is collected in the tank 9.
In the example of the present embodiment, most of the liquefied gas fuel is recovered at the time of the above-described liquid purge, so that the burden on the purge tank 9 during the vaporization purge is minimized. Therefore, even when a small purge tank 9 is used, the time required for vaporization purge is reduced.

  At the end of the vaporization purge, almost all of the liquefied gas fuel is purged from the inside of the high-pressure pump 5, the common rail 10, and the injector 13.

  The liquefied gas fuel supply device of the present embodiment described above has a high pressure from the in-tank feed pump as the first and second on-off valve devices provided in the gas phase introduction passage and the first purge passage connected to the common rail. An on-off valve device having a predetermined structure that opens and closes according to the pressure of the low-pressure fuel sent to the pump is employed. Therefore, the direct operation of the on-off valve device is not required, and the increase in the cost of the on-off valve device, and hence the liquefied gas fuel supply device can be suppressed. In addition, the on-off valve device of this embodiment can withstand high pressure in the common rail, and the reliability can be improved.

100: liquefied gas fuel supply device, 1: fuel tank, 2: in-tank feed pump, 3: prefilter, 4: filter, 5: high pressure pump, 6: reliquefaction compressor, 8: flow control valve, 9: purge tank DESCRIPTION OF SYMBOLS 10: Common rail, 12: Pressure control valve, 13: Fuel injection part (injector), 14: Overflow valve, 15: Flow sensor, 16: Fuel cooler, 17: Aspirator, 18a, 18b: Low-pressure fuel supply passage, 19: First opening / closing means, 20a / 20b: gas phase introduction passage, 22: second purge passage, 23: second opening / closing means, 24a / 24b: first purge passage, 25a / 25b: low pressure introduction passage , 26: third purge passage, 27: fourth opening / closing means, 28: fuel circulation passage, 29: third opening / closing means, 30a, 30b, 30c, 30d, 30e Fuel return passage, 31/33: check valve, 37a / 37b / 39: high pressure fuel passage, 50a: first on / off valve device, 50b: second on / off valve device, 51: cylinder body, 51a: cylinder, 51b : Fuel gallery, 52: pressure chamber, 53: valve piston, 53a: radial passage, 53b: axial passage, 53c: pressure receiving surface, 55: coil spring, 57: stopper, 57a: axial passage, 61: first Port 63: second port 65: third port

Claims (3)

The liquefied gas fuel in the fuel tank is sent to a high pressure pump by a feed pump, the liquefied gas fuel is pressurized by the high pressure pump and pumped to a common rail to which a fuel injection part of an internal combustion engine is connected, and the internal combustion engine In the liquefied gas fuel supply device for supplying the liquefied gas fuel to the engine,
A purge means for recovering the liquefied gas fuel in the common rail into the fuel tank while introducing the gaseous component of the liquefied gas fuel into the common rail after the internal combustion engine is stopped;
The purge means includes a purge passage and / or a gas phase introduction passage connected to the common rail, and is provided in the purge passage and / or the gas phase introduction passage. A pressure receiving portion that receives fuel pressure sent to the high-pressure pump, and includes an on-off valve device that closes when the fuel pressure is equal to or higher than a predetermined value and opens when the fuel pressure is lower than the predetermined value. A liquefied gas fuel supply device for an internal combustion engine characterized by the above. The on-off valve device is
Connected to the first port connected to the common rail, the second port into which a part of the liquefied gas fuel sent from the feed pump to the high pressure pump flows, and the suction part or the gas phase introduction part of the liquefied gas fuel A cylinder body having a third port,
A piston valve member that has the pressure receiving portion for receiving the fuel pressure flowing in from the second port and is housed in the cylinder body so as to communicate and block the first port and the third port;
A spring member for biasing the piston valve member so that the piston valve member can communicate and block the first port and the third port according to the fuel pressure;
The liquefied gas fuel supply device for an internal combustion engine according to claim 1, comprising:   The on-off valve device is connected to a low-pressure fuel supply passage between the feed pump and a pressure regulating valve that regulates the pressure of the liquefied gas fuel that is fed by the feed pump and sent to the high-pressure pump. The liquefied gas fuel supply device for an internal combustion engine according to claim 1 or 2, wherein the liquefied gas fuel supply device is used.

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