JP4410601B2 - Fuel supply device - Google Patents

Description

  The present invention relates to a fuel supply apparatus.

  2. Description of the Related Art Conventionally, in an internal combustion engine that uses LPG (liquefied petroleum gas), which is liquefied gas fuel, as a fuel, a fuel supply device is provided for supplying LPG injected from the injector to the injector. This fuel supply device pressurizes and supplies LPG in the fuel tank to the delivery pipe connected to the injector through the supply pipe by driving the fuel pump, and returns the excess LPG in the delivery pipe to the fuel tank through the return pipe. Is.

  By the way, in order to maintain various devices of the fuel supply system in the internal combustion engine, it is necessary to remove a part of the injector, the delivery pipe, the piping of the fuel supply device, etc., but at that time, LPG should not be released to the atmosphere as much as possible. It is hoped that. For this reason, during the maintenance, the engine is operated with the fuel tank shut off from the supply pipe and the return pipe, and the LPG in the delivery pipe, the supply pipe and the return pipe is injected from the injector and consumed. The LPG is reduced.

  However, in the engine operation in such a situation, since the fuel tank is shut off from the supply pipe, the pressurized supply of LPG toward the delivery pipe is not performed. For this reason, the pressure of the LPG supplied to the injector decreases with time, and the LPG pressure necessary for engine operation cannot be obtained, and before the LPG in the delivery pipe, supply pipe, and return pipe is completely consumed. This leads to a stall of the internal combustion engine. At this time, a large amount of LPG still remains in the tubes, and it is inevitable that the LPG is released into the atmosphere during maintenance.

Therefore, as shown in Patent Document 1, an intake / desorption tank is connected to the supply pipe through an on-off valve, and the LPG present in the supply pipe is heated and vaporized after the engine is stopped, so that the pressure in the supply pipe is increased. It has been proposed to open an on-off valve and collect LPG in the same pipe in an adsorption / desorption tank when the value exceeds a predetermined value.
JP-A-5-60019

  In Patent Document 1, LPG present in the supply pipe can be reduced by the amount of LPG collected in the adsorption / desorption tank. However, in the LPG recovery to the degassing tank using the pressure increase due to LPG vaporization in the supply pipe, the recovery is not performed when the pressure in the pipe becomes less than a predetermined value, and the delivery pipe after the recovery, Many LPGs still remain in the supply piping and return piping. Therefore, at the time of maintenance, LPG existing in these pipes is released into the atmosphere.

  The present invention has been made in view of such a situation, and an object of the present invention is to prevent the liquefied gas fuel existing in the piping of the fuel supply device from being released into the atmosphere during maintenance. It is to provide a fuel supply device.

In the following, means for achieving the above object and its effects are described.
In order to achieve the above object, according to the first aspect of the present invention, the liquefied gas fuel in the fuel tank is supplied to the delivery pipe connected to the injector through the supply pipe, and the excess liquefied gas fuel in the delivery pipe is returned to the return pipe. In the fuel supply device that returns to the fuel tank through A pressure regulator that permits outflow, an on-off valve that opens and closes to prohibit / permit outflow of liquefied gas fuel from the fuel tank to the supply pipe, and is provided in at least one of the supply pipe and the return pipe, to allow the introduction of compulsory inert gas to these pipes, before the introduction of the inert gas The liquefied gas fuel remaining in the pipe between the opening and closing valve and the pressure regulator and a service port that allows the recovered swept away to the fuel tank.

  According to the above configuration, the on-off valve is closed to prohibit the liquefied gas fuel from flowing out from the fuel tank to the supply pipe, and in this state, the fuel gas is injected from the injector and the liquefied gas fuel existing in the supply pipe and the delivery pipe is present. It is possible to forcibly introduce an inert gas from the service port after reducing the value. The inert gas thus introduced flows downstream and pushes the liquefied gas fuel remaining in the pipe to the fuel tank through the return passage. Further, if the on-off valve is opened after the introduction of the inert gas to some extent, the inert gas introduced into the pipe also flows upstream, and the liquefied gas fuel remaining in the pipe is supplied to the fuel via the supply pipe. It will also be washed away into the tank. As described above, after the liquefied gas fuel remaining in the pipe is collected by being pushed into the fuel tank, if a part of the piping of the fuel supply device for maintenance is removed, the liquefied gas fuel is brought into the atmosphere at that time. Release can be suppressed.

According to the second aspect of the present invention, the liquefied gas fuel in the fuel tank is supplied to the delivery pipe to which the injector is connected through the supply pipe, and the excess liquefied gas fuel in the delivery pipe is returned to the fuel tank through the return pipe. A pressure regulator that prohibits outflow of the liquefied gas fuel from the fuel tank to the return pipe and permits the outflow of the liquefied gas fuel from the pipe to the fuel tank based on the pressure in the return pipe; An on-off valve that opens and closes to prohibit / permit the outflow of liquefied gas fuel from the fuel tank to the supply pipe, and is provided downstream of the on-off valve in the supply pipe and is forcedly inactivated to the pipe to allow the introduction of the gas, and the pressure regulator and the on-off valve by the introduction of the inert gas The liquefied gas fuel remaining in the pipe and a service port that allows the recovered swept away to the fuel tank.

  According to the above configuration, the on-off valve is closed to prohibit the liquefied gas fuel from flowing out from the fuel tank to the supply pipe, and in this state, the fuel gas is injected from the injector and the liquefied gas fuel existing in the supply pipe and the delivery pipe is present. It is possible to forcibly introduce an inert gas into the supply pipe from the service port downstream of the on / off valve. The inert gas thus introduced into the supply pipe flows from the supply pipe to the fuel tank through the delivery pipe and the return pipe. As a result, the liquefied gas fuel existing in the pipes is pushed into the fuel tank by the inert gas and is collected in the tank. As described above, after the liquefied gas fuel in the supply pipe, delivery pipe, and return pipe is collected in the fuel tank, if part of the pipe of the fuel supply device for maintenance is removed, the liquefaction will occur at that time. The gaseous fuel can be prevented from being released into the atmosphere. If the on-off valve is opened after a certain amount of inert gas is introduced from the service port, the inert gas introduced into the supply pipe flows upstream, and the liquefied gas fuel remaining in the pipe is left. Will be pushed away from the supply pipe to the fuel tank, and the recovery of the liquefied gas fuel into the tank will be performed more rapidly.

According to a third aspect of the present invention, in the second aspect of the present invention, the service port is provided in the vicinity of the on-off valve.
When the inert gas is introduced into the supply pipe from the service port with the on-off valve closed, the liquefied gas fuel existing downstream (delivery pipe side) from the service port in the pipe is pushed toward the fuel tank. It becomes like this. However, the liquefied gas fuel existing upstream (on the on-off valve side) from the service port in the pipe remains without being pushed away to the fuel tank side when the on-off valve is not opened after the introduction of the inert gas. . According to the above configuration, since the service port is provided in the vicinity of the on-off valve, the portion between the service port and the on-off valve in the supply piping is shortened as much as possible, and the liquefied gas remaining in the portion when the inert gas is introduced Fuel can be kept to a minimum. Therefore, even if the LPG remaining in the portion is released into the atmosphere during maintenance, it does not become a problem. Note that the liquefied gas fuel remaining between the service port and the on-off valve in the supply pipe can be recovered in the fuel tank by opening the on-off valve after the introduction of the inert gas.

  According to a fourth aspect of the present invention, in the second or third aspect of the present invention, a plurality of the service ports are provided at predetermined intervals along the supply pipe, and the service ports are separated from the on-off valve in the supply pipe. A shut-off valve that opens and closes in order to prohibit / permit the flow of the liquefied gas fuel in the supply pipe is assumed to be provided in the vicinity of the upstream side.

  According to the above configuration, with the open / close valve closed, the inert gas is introduced from the service port located upstream of the part to be maintained of the fuel supply device, so that the part including the part is further downstream than the service port. The existing liquefied gas fuel is recovered in the fuel tank. Further, when the service port is away from the on-off valve, the liquefied gas fuel remaining between the service port and the on-off valve in the supply pipe is closed by closing the shutoff valve in the vicinity of the upstream of the service port. Can be prevented from being released into the atmosphere during maintenance. As described above, it becomes possible to collect only the liquefied gas fuel downstream from the portion to be maintained of the fuel supply device, in other words, only the liquefied gas fuel that needs to be collected in the maintenance, into the fuel tank. The amount of inert gas introduced into the supply pipe for recovery can be reduced. If the shut-off valve and the on-off valve are opened after the introduction of the inert gas, the liquefied gas fuel remaining between the service port and the on-off valve in the supply pipe is not sealed in that portion, but in the fuel tank. It can also be recovered.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the return pipe and the fuel tank communicate with each other by a bypass pipe that bypasses the pressure regulator, and the liquefied gas in the bypass pipe It is assumed that a bypass valve is provided to open and close to prohibit / permit fuel flow.

  According to the above configuration, when introducing the inert gas from the service port into the supply pipe with the open / close valve closed, the bypass valve is opened to allow the liquefied gas fuel to flow through the bypass pipe. Thus, the liquefied gas fuel recovered from the return passage to the fuel tank bypasses the pressure regulator and returns from the bypass pipe to the fuel tank. The pressure regulator permits the flow of liquefied gas fuel from the return pipe to the fuel tank when the pressure in the return pipe reaches a predetermined value or more. If a bypass pipe is not provided, when recovering LPG from the return passage to the fuel tank, a high-pressure inert gas is introduced from the service port so that the pressure in the return passage is equal to or higher than the predetermined value. Will have to. However, by providing a bypass pipe and opening the bypass valve as described above, the liquefied gas fuel can be recovered from the return passage through the bypass pipe to the fuel tank simply by introducing a low-pressure inert gas from the service port. It becomes possible to do. Further, if the shutoff valve and the on-off valve are opened after the introduction of the inert gas, the liquefied fuel is also recovered from the supply passage to the fuel tank, so that the recovery can be performed more rapidly.

  According to a sixth aspect of the present invention, in the invention according to any one of the first to fourth aspects, another service for connecting an end portion of a bypass pipe that bypasses the pressure regulator to the return pipe and the fuel tank. Ports are provided, and other service ports are provided with bypass valves that open and close to prohibit / permit the flow of liquefied gas fuel.

  According to the above configuration, by connecting the end of the bypass pipe to the other service port, opening the bypass valve and allowing the liquefied gas fuel to flow between the other service port and the bypass pipe, The return pipe and the fuel tank are in communication with each other through the bypass pipe. In such a state, when the on-off valve is closed and the inert gas is introduced into the supply pipe, the liquefied gas fuel collected in the fuel tank bypasses the pressure regulator and returns from the bypass pipe to the fuel tank. The pressure regulator permits the flow of liquefied gas fuel from the return pipe to the fuel tank when the pressure in the return pipe reaches a predetermined value or more. If the bypass pipe is not connected to the other service port, a high-pressure inert gas is introduced from the service port so that the pressure in the return passage exceeds the predetermined value in order to recover LPG to the fuel tank. Will have to do. However, by connecting the bypass pipe to another service port and opening the bypass valve as described above, liquefied gas fuel can be supplied to the fuel tank through the bypass pipe simply by introducing a low-pressure inert gas from the service port. Can be recovered. If the shutoff valve and the on-off valve are opened after the introduction of the inert gas, the liquefied fuel is also collected from the supply passage to the fuel tank, so that the collection can be performed more quickly. If the bypass valve of another service port is closed, the bypass pipe can be separated from the other service port. Can only be attached and used.

[First Embodiment]
Hereinafter, a first embodiment in which the present invention is embodied in an engine fuel supply device will be described with reference to FIGS.

  The engine 1 in FIG. 1 is injected from an injector 2 using LPG (liquefied petroleum gas) as fuel, and is driven by mixing the LPG with air sucked from an intake passage 3 and burning it. The fuel supply device of the engine 1 is for supplying LPG to a delivery pipe 4 connected to an injector 2.

  The fuel supply device includes a fuel pump 6 that pumps up and discharges LPG in the fuel tank 5, a supply pipe 7 that supplies the fuel discharged from the fuel pump 6 to the delivery pipe 4, and an excess in the delivery pipe 4. A return pipe 8 for returning the LPG to the fuel tank 5 is provided.

  At the upstream end of the supply pipe 7, that is, the end on the fuel tank 5 side, there is provided a liquid phase on-off valve 9 that can be opened and closed to prohibit / permit the outflow of LPG from the fuel tank 5 to the supply pipe 7. . The liquid phase on / off valve 9 is normally kept open to allow the outflow of LPG from the fuel tank 5, and is manually closed when the outflow of LPG from the fuel tank 5 should be prohibited, such as during maintenance. It is supposed to be.

  In the supply pipe 7, a tank cutoff valve 11 that is controlled to be opened and closed by an electronic control device 10 is provided in the vicinity of the downstream side of the liquid phase opening and closing valve 9. The tank shut-off valve 11 is opened to allow the LPG flow through the supply pipe 7 when the engine 1 is driven, and is closed to prohibit the LPG flow through the supply pipe 7 when the engine 1 is stopped. Open / close controlled. Such opening / closing control of the tank cutoff valve 11 prevents LPG in the fuel tank 5 from flowing downstream from the tank cutoff valve 11 in the supply pipe 7 when the engine 1 is stopped. The tank shut-off valve 11 can be manually opened and closed.

  In the supply pipe 7, a delivery cutoff valve 12 that is controlled to be opened and closed by the electronic control device 10 is provided in the vicinity of the delivery pipe 4. The delivery shut-off valve 12 is also opened to allow LPG flow through the supply pipe 7 when the engine 1 is driven, and closed to prohibit LPG flow through the supply pipe 7 when the engine 1 is stopped. Open / close controlled. Such opening / closing control of the delivery cutoff valve 12 prevents the LPG in the delivery pipe 4 from flowing upstream from the delivery cutoff valve 12 in the supply pipe 7 when the engine 1 is stopped. The delivery cutoff valve 12 can also be manually opened and closed.

  The portion of the return pipe 8 connected to the fuel tank 5 (downstream end) prohibits the outflow of LPG from the fuel tank 5 to the return pipe 8 and fuel from the pipe 8 based on the pressure in the return pipe 8. A pressure regulator 13 that permits the outflow of LPG to the tank 5 is provided. The pressure regulator 13 permits the outflow of LPG from the pipe 8 to the fuel tank 5 when the pressure in the return pipe 8 increases to a certain level and exceeds a predetermined value.

  In addition, a gas pipe 14 for sending LPG vaporized in the tank 5 to the intake passage 3 is opened and closed in the fuel tank 5 to prohibit / permit the outflow of vaporized LPG from the fuel tank 5 to the gas pipe 14. It is connected via an operating gas-phase on-off valve 15. The gas-phase on-off valve 15 is normally kept open to allow the vaporized LPG to flow out of the fuel tank 5 and is manually closed when the vaporized LPG should be prohibited from flowing out of the fuel tank 5 such as during maintenance. It is a valve state. On the other hand, a control valve 16 whose opening degree is controlled to adjust the amount of vaporized LPG flowing from the gas pipe 14 to the intake passage 3 is provided at the end (downstream end) of the gas pipe 14 on the intake passage 3 side. Yes. The opening control of the control valve 16 is performed through the electronic control device 10.

  By the way, when maintaining various devices of the fuel supply system in the engine 1, such as the injector 2, the delivery pipe 4, the tank shut-off valve 11, and the delivery shut-off valve 12, a part of the piping of these devices and the fuel supply device. Need to be removed. When removing a part of these various devices and pipes, it is desirable to prevent LPG from being released into the atmosphere as much as possible.

  Therefore, in the present embodiment, an inert gas such as nitrogen gas is introduced into the supply pipe 7, the return pipe 8, and the delivery pipe 4 of the fuel supply device before maintenance, and the pipes 7 and 8 are used by the inert gas. The LPG remaining in the delivery pipe 4 is returned to the fuel tank 5. Thus, after the LPG existing in the pipes 7 and 8 and the delivery pipe 4 is collected in the fuel tank 5, the equipment and pipes for maintenance are removed.

  Next, a structure for introducing an inert gas into the pipes 7 and 8 and the delivery pipe 4, and a structure for returning the LPG existing in the pipes 7 and 8 and the delivery pipe 4 to the fuel tank 5 Are individually described below.

[Structure for introducing inert gas]
The supply pipe 7 is provided with a plurality (two in this embodiment) of service ports 17 and 18 that allow forced introduction of inert gas into the pipe 7. These service ports 17 and 18 are provided at predetermined intervals along the supply pipe 7. The service port 17 is located in the vicinity of the downstream of the liquid phase opening / closing valve 9, and the service port 18 is located in the vicinity of the downstream of the delivery cutoff valve 12.

The detailed structure of the service ports 17 and 18 is shown in FIG.
The service ports 17, 18 include a passage 19 connected to the supply pipe 7, a passage 20 connected to the outside of the service ports 17, 18, and a manual valve 21 that is manually opened and closed to connect and disconnect the passages 19, 20. I have. The passages 20 of the service ports 17 and 18 are connected via a coupler 24 to a pipe 23 extending from an inert gas supply source. The coupler 24 includes a coupler plug 24 a connected to the passage 20 and a coupler socket 24 b connected to the pipe 23, and connects the passage 20 and the pipe 23 by detachably connecting them. If the coupler socket 24b is removed from the coupler plug 24a, the pipe 23 can be disconnected from the passage 20, and the disconnected state is set in a normal state when the inert gas is not introduced into the supply pipe 7.

[Structure for returning LPG to the fuel tank]
As shown in FIG. 1, service ports 26 and 27 for connecting a bypass pipe 25 are provided upstream of the pressure regulator 13 in the return pipe 8 and in the fuel tank 5. The bypass pipes 25 connected to the service ports 26 and 27 bypass the pressure regulator 13 and connect the return pipe 8 and the fuel tank 5. The bypass pipe 25 is provided with a pressure gauge 25a for measuring the pressure in the pipe 25.

Here, the detailed structures of the service ports 26 and 27 and the bypass pipe 25 are shown in FIG.
The service port 26 includes a passage 28 connected to the return pipe 8, a passage 29 connected to the outside of the service port 26, and a manual valve 30 (bypass valve) that is manually opened and closed to connect and disconnect the passages 28 and 29. I have. The passage 29 is divided into two passages 29a and 29b. One end of the bypass pipe 25 is connected to one of the passages 29a via a coupler 31, and an LPG gas detector 32 is connected to the other passage 29b. Connection is made via a coupler 33.

  The coupler 31 is the same as the coupler 24 described above, and includes a coupler plug 31a connected to one end of the bypass pipe 25 and a coupler socket 31b connected to the passage 29a. It is for connecting one end and the passage 29a. If the coupler plug 31a is removed from the coupler socket 31b, the bypass pipe 25 can be disconnected from the passage 29a, and in such a normal state that the inert gas is not introduced into the supply pipe 7.

  The coupler 33 is also the same as the coupler 24, and includes a coupler plug 33a connected to the LPG gas detector 32 and a coupler socket 33b connected to the passage 29b. This is for connecting the gas detector 32 and the passage 29b. If the coupler plug 33a is removed from the coupler socket 33b, the LPG gas detector 32 can be disconnected from the passage 29b, and in such a normal state when the inert gas is not introduced into the supply pipe 7. ing.

  On the other hand, the service port 27 includes a passage 34 connected to the fuel tank 5, a passage 35 connected to the outside of the service port 27, and a manual valve 36 (bypass valve) that is manually opened and closed to connect and disconnect the passages 34 and 35. And. Then, the other end of the bypass pipe 25 is connected to the passage 35 via a coupler 37.

  The coupler 37 is the same as the coupler 24, and includes a coupler plug 37 a connected to the passage 35 and a coupler socket 37 b connected to the other end of the bypass pipe 25. The coupler 37 is detachably connected to the passage 35. This is for connecting the other end of the bypass pipe 25. If the coupler plug 37a is removed from the coupler socket 37b, the bypass pipe 25 can be disconnected from the passage 35, and in such a normal state when the inert gas is not introduced into the supply pipe 7.

Next, a procedure for removing various devices of the fuel supply system in the engine 1 for maintenance will be described with reference to FIG.
For maintenance, first, the engine 1 is operated with the liquid-phase on-off valve 9 and the gas-phase on-off valve 15 closed. At this time, although the tank shutoff valve 11 and the delivery shutoff valve 12 are open, the liquid phase on / off valve 9 is closed, so that LPG is not supplied from the fuel tank 5 to the supply pipe 7. For this reason, when the engine operation is continued, the LPG existing in the delivery pipe 4 and the supply pipe 7 is consumed and reduced, and the pressure of the LPG supplied to the injector 2 is lowered, which eventually causes an engine stall. It will be. By operating until the engine 1 is stalled in this way, the LPG existing in the supply pipe 7 and the delivery pipe 4 is reduced as much as possible.

  Thereafter, as shown in FIG. 3, the coupler plug 31a of the bypass pipe 25 is connected to the coupler socket 31b of the service port 26, and the coupler plug 33a of the LPG gas detector 32 is connected to the coupler socket 33b. Further, the coupler socket 37 b of the bypass pipe 25 is connected to the coupler plug 37 a of the service port 27. Then, with the bypass pipe 25 and the LPG gas detector 32 connected, the manual valves 30 and 36 of the service ports 26 and 27 are opened, and the tank shut-off valve 11 and the delivery shut-off that are closed when the engine is stalled. Open the valve 12 (FIG. 1). Thus, by opening the valves 30, 36, 11, 12, a part of the liquefied gas fuel existing in the return pipe 8, the delivery pipe 4, and the supply pipe 7 is transferred to the fuel tank 5 via the bypass pipe 25. The flow, the return pipe 8, the delivery pipe 4, the supply pipe 7, and the pressure in the fuel tank 5 are made uniform.

  Subsequently, an operation for introducing an inert gas into the supply pipe 7 is performed. Here, in order to reduce the introduction amount of the inert gas as much as possible, the inert gas is introduced into the supply pipe 7 from the service ports 17 and 18 immediately upstream of the portion to be maintained, and the portion including the portion to be maintained is included. LPG existing downstream is recovered in the fuel tank 5 by the inert gas. Therefore, the work for introducing the inert gas and the work after that differ depending on the part to be maintained. In the following, the work after the introduction of the inert gas will be described individually by taking as an example the case where maintenance of the tank cutoff valve 11 and the delivery cutoff valve 12 is performed and the case where maintenance around the delivery pipe 4 is performed.

[Maintenance of tank shutoff valve 11 and delivery shutoff valve 12]
In this case, the inert gas is introduced into the supply pipe 7 from the service port 17 located in the vicinity of the downstream side of the liquid phase on-off valve 9. Specifically, as shown in FIG. 2, the coupler socket 24 b of the pipe 23 extending from the inert gas supply source is connected to the coupler plug 24 a of the service port 17. Then, the manual valve 21 of the service port 17 is opened, and then an inert gas is introduced into the supply pipe 7 through the pipe 23 and the service port 17 (passages 20 and 19). Note that the introduction pressure of the inert gas at this time is higher than the pressure indicated by the pressure gauge 25 a provided in the bypass pipe 25, in other words, in the fuel tank 5, the return pipe 8, the delivery pipe 4, and the supply pipe 7. It is set to a value higher than the pressure.

  Then, the inert gas introduced into the supply pipe 7 as described above flows to the downstream side (delivery pipe 4 side) of the service port 17 in the supply pipe 7 of FIG. As a result, the LPG existing in the supply pipe 7 downstream of the service port 17, the delivery pipe 4, and the return pipe 8 is pushed toward the fuel tank 5 by the inert gas and collected in the tank 5. Is done. When the LPG recovered in the fuel tank 5 is returned from the return pipe 8 to the fuel tank 5, it flows into the fuel tank 5 from the bypass pipe 25 that bypasses the pressure regulator 13.

  After introducing the inert gas into the supply pipe 7 as described above, whether or not the LPG has been removed from the supply pipe 7, the delivery pipe 4, and the return pipe 8 is confirmed by the LPG gas detector 32 (see FIG. This is performed based on whether LPG is detected in 3). Such confirmation is performed with the manual valves 21, 30, and 36 of the service ports 17, 26, and 27 closed.

  Here, when the LPG is detected by the LPG gas detector 32, this means that the LPG is not completely removed from the supply pipe 7, the delivery pipe 4, and the return pipe 8. 26, 27 are opened again, and the introduction of the inert gas is repeated. On the other hand, when LPG is not detected by the LPG gas detector 32, this means that the LPG is completely removed from the supply pipe 7, the delivery pipe 4, and the return pipe 8. In this case, even if a part of the piping in the tank cutoff valve 11, the delivery cutoff valve 12, and the supply piping 7 is removed, LPG is not released to the atmosphere, and maintenance is performed after removing them.

[During maintenance around the delivery pipe 4]
In this case, the inert gas is introduced into the supply pipe 7 from the service port 18 located in the vicinity of the downstream side of the delivery cutoff valve 12, in other words, from the service port 18 away from the liquid phase opening / closing valve 9 in the same manner as described above. Specifically, as shown in FIG. 3, the coupler socket 24 b of the pipe 23 extending from the inert gas supply source is connected to the coupler plug 24 a of the service port 18. Then, the manual valve 21 of the service port 18 is opened, and then the inert gas is introduced into the supply pipe 7 through the pipe 23 and the service port 18 (passages 20 and 19).

  By introducing such an inert gas, LPG existing downstream from the service port 18 is pushed away toward the fuel tank 5 and recovered, but LPG existing upstream from the service port 18 is pushed away toward the fuel tank 5. It remains without. Therefore, before the introduction of the inert gas, the delivery shutoff valve 12 is closed, and the LPG existing between the upstream and downstream liquid phase on-off valves 9 is sealed in the supply pipe 7, LPG is prevented from being released into the atmosphere during maintenance.

  After introducing the inert gas into the supply pipe 7, it is confirmed whether or not LPG has been removed from the service pipe 18 downstream of the supply pipe 7, the delivery pipe 4, and the return pipe 8. This is performed based on whether or not LPG is detected by the LPG gas detector 32 (FIG. 3). When the LPG is not completely removed, the introduction of the inert gas described above is repeated. On the other hand, if the LPG is completely removed, the LPG will not be released to the atmosphere even if the periphery of the delivery pipe 4 is removed, so that maintenance is performed by removing them.

  As described above, when LPG is recovered in the fuel tank 5 by introducing the inert gas into the supply pipe 7, not only LPG but also inert gas enters the fuel tank 5. Thus, the inert gas that has entered the fuel tank 5 gradually enters the intake passage 3 through the opening control of the control valve 16 of the gas pipe 14 during engine operation to the extent that it does not affect the operation together with the vaporized LPG. Released.

According to the embodiment described in detail above, the following effects can be obtained.
(1) LPG present in the supply pipe 7, delivery pipe 4, and return pipe 8 by introducing an inert gas from the service port 17 into the supply pipe 7 with the liquid phase on-off valve 9 closed. Is pushed away to the fuel tank 5 side by the inert gas and collected in the tank 5. After the LPG is collected in the fuel tank 5 in this way, the supply pipe 7, the delivery pipe 4, the return pipe 8 and the like for maintenance are removed, and at that time, the LPG is released into the atmosphere. Can be suppressed.

  (2) The service port 17 is provided in the vicinity of the downstream side of the liquid phase on-off valve 9. For this reason, by introducing the inert gas from the service port 17 to the supply pipe 7, the supply pipe 7, the delivery pipe 4, and the return are caused by the flow of the inert gas toward the downstream side (delivery pipe 4 side). Most of the LPG remaining in the pipe 8 can be recovered in the fuel tank 5. Further, even when an inert gas is introduced from the service port 17 into the supply pipe 7, LPG existing on the upstream side (liquid phase on-off valve 9 side) from the service port 18 remains without being pushed away to the fuel tank 5 side. However, since the service port 17 is provided in the vicinity of the downstream side of the liquid phase opening / closing valve 9, the portion between the service port 17 and the liquid phase opening / closing valve 9 in the supply pipe 7 is shortened as much as possible, and the inert gas LPG remaining in the portion at the time of introduction can be minimized. Therefore, even if LPG remaining in the portion is released into the atmosphere during maintenance, it does not cause a problem.

  (3) Since the service ports 17 and 18 are provided in the supply pipe 7 along the pipe 7 at a predetermined interval, the service port located immediately upstream of the portion to be maintained is inactive to the supply pipe 7. By introducing the gas, LPG existing on the downstream side of the service port including the portion to be maintained is recovered in the fuel tank 5. Further, when an inert gas is introduced into the supply pipe 7 from the service port 18 away from the liquid phase opening / closing valve 9, the LPG existing upstream from the service port 18 and between the liquid phase opening / closing valve 9. Is left without being pushed away to the fuel tank 5 side by the inert gas. However, the delivery shutoff valve 12 is located in the vicinity of the upstream of the service port 18, and when the inert gas is introduced from the service port 18, the delivery shutoff valve 12 is closed to close the shutoff valve 12 and the liquid phase on / off valve. 9 is sealed in the supply pipe 7 and is prevented from being released into the atmosphere during maintenance. As described above, it becomes possible to collect only the LPG on the downstream side of the portion to be maintained, in other words, only the LPG that needs to be collected in the maintenance, into the fuel tank 5, and supply piping 7 for the collection. The amount of inert gas introduced into the can be reduced.

  (4) When the inert gas is introduced into the supply pipe 7, the bypass pipe 25 is connected to the return pipe 8 and the fuel tank 5, and the manual valves 30, 36 of the service ports 26, 27 are opened to bypass the bypass pipe. The distribution of LPG at 25 is permitted. Accordingly, the LPG recovered in the fuel tank 5 with the introduction of the inert gas bypasses the pressure regulator 13 and returns to the fuel tank 5 via the bypass pipe 25. If the bypass pipe 25 is not provided, the pressure regulator 13 allows the LPG to flow from the return pipe 8 to the fuel tank 5 when the pressure in the return pipe 8 exceeds a predetermined level as a result of the introduction of the inert gas. Then, the LPG is collected into the fuel tank 5. For this reason, in order to recover LPG to the fuel tank 5, high-pressure inert gas must be introduced from the service ports 17 and 18 into the supply pipe 7 so that the pressure in the return pipe 8 becomes a predetermined value or more. No longer. However, if the bypass pipe 25 is connected to the return pipe 8 and the fuel tank 5 and the manual valves 30 and 36 of the service ports 26 and 27 are opened as described above, low-pressure inert gas is supplied from the service ports 17 and 18. It is possible to recover LPG into the fuel tank 5 through the bypass pipe 25 only by introducing the fuel.

In addition, the said embodiment can also be changed as follows, for example.
The bypass pipe 25 may be attached and fixed in a state where it is connected to the return pipe 8 and the fuel tank 5 so that the bypass pipe 25 cannot be removed from the return pipe 8 and the fuel tank 5. When the bypass pipe 25 is removable from the return pipe 8 and the fuel tank 5 as in the above embodiment, the bypass pipe 25 is removed when it is not necessary, and is attached and used only when necessary. Can do.

  The bypass pipe 25 is not necessarily used when recovering LPG to the fuel tank 5. That is, without connecting the bypass pipe 25 to the return pipe 8 and the fuel tank 5, the inert gas is introduced into the supply pipe 7, and the pressure regulator 13 is set to a predetermined value or higher by setting the pressure in the return pipe 8 to a predetermined value or more. The LPG may be collected in the fuel tank 5 via In this case, the service ports 26 and 27 can be omitted.

  -Three or more service ports may be provided in the supply pipe 7 along the pipe 7 at predetermined intervals. In this case, a shut-off valve is provided in the vicinity of each service port, and when an inert gas is introduced from a certain service port, the shut-off valve located immediately upstream of the service port is closed and is present upstream of the shut-off valve. The LPG is sealed in the supply pipe 7.

  When a device requiring maintenance is provided in the return pipe 8, a service port and a shut-off valve may be provided upstream of the device in the return pipe 8. In this case, it is preferable to provide the service port and the shutoff valve in the vicinity of the upstream side of the equipment requiring maintenance.

  Only the service port 17 in the vicinity of the downstream side of the liquid phase opening / closing valve 9 may be provided in the supply pipe 7. In this case, the inert gas is introduced from the service port 17 regardless of the part to be maintained.

  The position of the service port 18 may be changed to the downstream side of the liquid phase opening / closing valve 9. Such a change is preferably performed within a range where there is no problem even if LPG remaining upstream from the service port 18 is released into the atmosphere during maintenance.

  After the introduction of the inert gas from the service ports 17 and 18 to the supply pipe 7, the tank shutoff valve 11, the delivery shutoff valve 12, and the liquid phase on / off valve 9 may be opened. In this case, the inert gas introduced into the supply pipe 7 from the service ports 17 and 18 also flows upstream. For this reason, the liquefied gas fuel sealed upstream of the service ports 17 and 18 in the supply pipe 7 by closing the shutoff valve 11 and the delivery shutoff valve 12 is pushed into the fuel tank 5 by the inert gas. Collected. In this case, the LPG remaining in the supply pipe 7, the delivery pipe 4, and the return pipe 8 is returned to the fuel tank 5 through both the supply pipe 7 and the return pipe 8, so that all the LPG will be collected in the fuel tank 5. In this case, the recovery can be performed more promptly.

  -Although LPG (liquefied petroleum gas) was illustrated as liquefied gas fuel used as a fuel of engine 1, other liquefied gas fuel, for example, LNG (liquefied natural gas), may be used instead.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG.
In this embodiment, as shown in FIG. 4, the supply pipe 7 is not provided with an inert gas introduction service port, and only the return pipe 8 is provided with an inert gas introduction service port 40. is there. Hereinafter, the procedure for removing the various devices of the fuel supply system in this embodiment will be described mainly with respect to the differences from the first embodiment.

  First, the engine 1 is operated until the engine 1 is stalled with the liquid phase on-off valve 9 closed, and then the inert gas is introduced from the service port 40 into the return pipe 8. The inert gas introduced into the return pipe 8 in this manner flows downstream and pushes the LPG remaining in the return pipe 8 into the fuel tank 5 through the bypass pipe 25. Then, after introducing the inert gas to some extent, the liquid phase on-off valve 9, the tank shut-off valve 11, and the delivery shut-off valve 12 are opened. As a result, the inert gas introduced into the return pipe 8 also flows upstream, and the LPG remaining in the delivery pipe 4 and the supply pipe 7 is pushed into the fuel tank 5 through the supply pipe 7. As described above, after the liquefied gas fuel remaining in the supply pipe 7, the delivery pipe 4, and the return pipe 8 is collected by being pushed into the fuel tank 5, a part of the pipe of the fuel supply device for maintenance can be removed. Done.

According to this embodiment, in addition to the effect described in (1) in the first embodiment, the following effect can be obtained.
(5) The inert gas introduced from the service port 40 is caused to flow upstream and downstream, and the liquefied gas fuel remaining in the supply pipe 7, the delivery pipe 4, and the return pipe 8 is supplied to the supply pipe 7 and the return pipe 8. Both can be returned to the fuel tank 5. Accordingly, when all of the LPG remaining in the supply pipe 7, the delivery pipe 4, and the return pipe 8 is to be recovered in the fuel tank 5 by introducing the inert gas, the recovery can be performed more rapidly.

In addition, the said embodiment can also be changed as follows, for example.
The bypass pipe 25 may be attached and fixed while being connected to the return pipe 8 and the fuel tank 5.

  The return pipe 8 may be provided with two or more service ports along the pipe 8 at predetermined intervals. When the return pipe 8 is provided with a device that requires maintenance, a service port is provided upstream of the equipment in the return pipe 8, and a shut-off valve is provided in the vicinity of the service port upstream. May be. In this case, the inert gas is introduced into the return pipe 8 from the service port located upstream of the equipment to be maintained, and the shut-off valve located upstream of the service port is closed to the upstream side of the shut-off valve. By sealing the LPG present in the fuel tank 5, only the portion to be maintained and the LPG downstream thereof can be recovered in the fuel tank 5. Therefore, it is possible to recover only the amount that needs to recover LPG during maintenance, and to suppress the amount of inert gas introduced into the return pipe 8 for the recovery. become able to.

  A liquefied gas fuel other than LPG, for example, LNG (liquefied natural gas) may be used as the liquefied gas fuel used as the fuel for the engine 1.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows the whole fuel supply apparatus of 1st Embodiment, and the engine to which this apparatus is applied. Sectional drawing which shows the detailed structure of the service ports 17 and 18. FIG. Sectional drawing which shows the detailed structure of the service ports 26 and 27, and the connection structure of these service ports 26 and 27 and a bypass pipe. The schematic which shows the engine with which the whole fuel supply apparatus of 2nd Embodiment and this apparatus are applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Injector, 3 ... Intake passage, 4 ... Delivery pipe, 5 ... Fuel tank, 6 ... Fuel pump, 7 ... Supply piping, 8 ... Return piping, 9 ... Liquid phase on-off valve, 10 ... Electronic control apparatus 11 ... Tank shutoff valve, 12 ... Delivery shutoff valve, 13 ... Pressure regulator, 14 ... Gas piping, 15 ... Gas phase open / close valve, 16 ... Control valve, 17, 18 ... Service port, 19, 20 ... Passage, 21 ... Manual valve, 23 ... pipe, 24 ... coupler, 24a ... coupler plug, 24b ... coupler socket, 25 ... bypass pipe, 25a ... pressure gauge, 26,27 ... service port, 28,29,29a, 29b ... passage, 30 ... Manual valve (bypass valve), 31 ... coupler, 31a ... coupler plug, 31b ... coupler socket, 32 ... gas detector for LPG, 33 ... coupler, 33a ... coupler plug, 3 b ... coupler socket, 34, 35 ... passage, 36 ... manual valve (bypass valve), 37 ... coupler, 37a ... coupler plug, 37b ... coupler socket, 40 ... service port.

Claims (6)

In the fuel supply device for supplying the liquefied gas fuel in the fuel tank to the delivery pipe to which the injector is connected through the supply pipe, and returning the excess liquefied gas fuel in the delivery pipe to the fuel tank through the return pipe,
A pressure regulator that prohibits outflow of the liquefied gas fuel from the fuel tank to the return pipe, and permits outflow of the liquefied gas fuel from the pipe to the fuel tank based on the pressure in the return pipe;
An on-off valve that opens and closes to prohibit / permit flow of liquefied gas fuel from the fuel tank to the supply pipe;
It is provided in at least one of the supply pipe and the return pipe, and can forcibly introduce an inert gas into these pipes. Between the opening and closing valve and the pressure regulator, the inert gas is introduced. A service port that allows the liquefied gas fuel remaining in the piping to be pushed into the fuel tank and collected ;
A fuel supply device comprising: In the fuel supply device for supplying the liquefied gas fuel in the fuel tank to the delivery pipe to which the injector is connected through the supply pipe, and returning the excess liquefied gas fuel in the delivery pipe to the fuel tank through the return pipe,
A pressure regulator that prohibits outflow of the liquefied gas fuel from the fuel tank to the return pipe, and permits outflow of the liquefied gas fuel from the pipe to the fuel tank based on the pressure in the return pipe;
An on-off valve that opens and closes to prohibit / permit flow of liquefied gas fuel from the fuel tank to the supply pipe;
Provided downstream of the on-off valve in the supply pipe, enables forcible introduction of inert gas into the pipe, and the introduction of the inert gas in the pipe between the on-off valve and the pressure regulator A service port that allows the remaining liquefied gas fuel to be swept into the fuel tank and recovered ;
A fuel supply device comprising:   The fuel supply device according to claim 2, wherein the service port is provided in the vicinity of the on-off valve.   A plurality of the service ports are provided at predetermined intervals along the supply pipe, and the liquefied gas fuel in the supply pipe is not allowed to flow in the vicinity of the supply pipe upstream from the open / close valve. 4. The fuel supply device according to claim 2 or 3, further comprising a shut-off valve that opens and closes to allow it.   The bypass pipe that is connected to the return pipe and the fuel tank by a bypass pipe that bypasses the pressure regulator and is opened and closed to prohibit / permit the flow of the liquefied gas fuel in the bypass pipe is provided. 5. The fuel supply device according to any one of 4 above.   The return pipe and the fuel tank are provided with another service port for connecting an end of a bypass pipe that bypasses the pressure regulator, and the flow of the liquefied gas fuel is prohibited / permitted to the other service port. The fuel supply device according to any one of claims 1 to 4, further comprising a bypass valve that opens and closes as much as possible.

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