JP4342290B2 - Liquefied gas fuel supply device - Google Patents

Description

  The present invention relates to a liquefied gas fuel supply apparatus, and more particularly, to provide a charging / discharging system suitable for handling liquefied gas fuel such as liquefied petroleum gas (LPG) and liquefied natural gas (LNG).

  In an internal combustion engine or the like using liquefied gas fuel, as a technique for discharging liquid from the inside of a gas tank, for example, Japanese Patent Application Laid-Open No. 10-54304 provides a liquid discharge pipe that opens near the bottom of the tank and accumulates at the bottom of the tank. A technique is disclosed that allows the liquid to be discharged to the outside (Patent Document 1).

In addition, as a technique for filling gas fuel into a tank, for example, Japanese Patent Laid-Open No. 9-264196 is filled with a pressure relief mechanism that guides fuel in a filling hose to the engine side after filling a compressed natural gas (CNG) into a gas container. A technique is disclosed that is provided in communication with a hose and discharges gas in the hose accompanying filling to the outside (Patent Document 2).
JP-A-10-54304 JP-A-9-264196

  However, the liquid discharged in the above Japanese Patent Laid-Open No. 10-54304 is water generated accompanying the use of natural gas and does not disclose a structure for discharging the liquefied gas fuel itself. That is, conventionally, the operation of discharging the liquefied gas fuel from the tank has been performed manually, and a method for extracting the liquefied gas fuel with good serviceability has not been known.

  Further, the technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 9-264196 relates to depressurization for releasing the gas accumulated in the hose when the gas fuel is filled, but the air accumulated in the tank, etc. It did not provide a structure for releasing different gases. If the liquefied gas fuel is supplied to the internal combustion engine in a state where a different kind of gas such as air remains in the tank, the air-fuel ratio that greatly affects the combustion is distorted, and the operating performance and the stability at the start are adversely affected. For this reason, it is necessary to completely remove foreign gases such as air in the tank, but it is difficult to perform this operation manually.

  In other words, the conventional technology has not provided a configuration that supports the work required for extraction and filling of liquefied gas fuel, which is difficult to handle and vaporizes at normal temperature and normal pressure. For this reason, the labor cost has to be high through a laborious process involving manual labor.

  Therefore, the present invention has an object to provide a structure suitable for discharging liquefied gas fuel and to improve the serviceability of refilling operation of liquefied gas fuel by providing a structure that reliably discharges different gases during filling. To do.

  In order to solve the above-mentioned problem, a first invention is a liquefied gas fuel supply device for supplying liquefied gas fuel from a tank to an internal combustion engine, wherein the liquefied gas fuel stored in the tank is circulated and liquefied to the internal combustion engine. A circulation path for supplying gas fuel, a driving means for forcibly circulating the liquefied gas fuel in the tank into the circulation path, and a liquefied gas fuel discharged from the tank through at least a part of the circulation path. And a shut-off means for shutting off the flow of the path that does not include the drive means among the plurality of paths connecting the discharge means and the tank in the circulation path at least when the liquefied gas fuel is discharged. Features.

  According to the above configuration, when the liquefied gas fuel is discharged, one of the circulation paths connecting the tank and the discharge portion is blocked. At this time, since the driving means is provided in an uninterrupted path in the circulation path, the liquefied gas fuel in the tank is forcibly sucked out by driving the driving means, and the other of the circulation paths is It is discharged from the discharge section via. For this reason, the extraction operation of liquefied gas fuel is automated, and serviceability can be greatly improved.

  Here, the “driving means” is not limited, and examples thereof include a pump that generates a negative pressure and sucks out the liquefied gas fuel in the tank. A pump used for supplying liquefied gas fuel to the internal combustion engine during operation may also be used.

  Various forms of the “discharge section” are conceivable. For example, a pipe connected to a part of the circulation path or an opening provided directly on the circulation system path may be used. A switching means such as a three-way valve or a rotary valve may be provided at the connection part between the discharge part and the circulation path. Such a valve may function as the blocking means of the present invention.

  In addition, the said discharge part may function as a filling port at the time of filling a liquefied gas fuel into a tank through a circulation path.

  The “shut-off means” may be a so-called shut-off valve, and is preferably a computer-controllable device such as an electromagnetic valve. It may be a three-way valve or a rotary valve provided at a connection point between the discharge unit and the circulation path.

  At this time, the present invention further includes a control unit that controls opening and closing of the blocking unit, and the control unit is configured to close the blocking unit in accordance with an external discharge request for liquefied gas fuel. According to the above configuration, when the liquefied gas fuel is extracted, the circulation path for supplying the fuel automatically becomes the liquefied gas fuel extraction path, and the fuel can be extracted only by connecting an empty cylinder or the like to the discharge portion. .

  Here, the discharge request may be an electric signal input from an external service tool, for example, but may be configured such that the user can directly instruct the control unit.

  A second invention is a liquefied gas fuel supply device for supplying liquefied gas fuel from a tank to an internal combustion engine, and a gas discharge path for discharging different gases in the tank when the liquefied gas fuel is filled into the tank. And a control unit for determining whether or not the different gas is discharged from the tank based on the theoretical value of the vapor pressure in the tank and the actually measured value of the vapor pressure in the tank.

  According to the above configuration, before and after the liquefied gas fuel is filled in the tank, the different gas in the tank is discharged along the discharge path. The liquefied gas fuel filled in the tank theoretically shows a predetermined vapor pressure, but if a different gas remains in the tank, a deviation occurs in the measured vapor pressure. In the present invention, the control unit can check whether or not the different gas remains in the tank by comparing the theoretical value of the vapor pressure with the actually measured value.

  The theoretical value of the vapor pressure varies depending on the composition of the liquefied gas fuel. For this reason, it is also possible to determine what the composition of the liquefied gas fuel is by using the measured value of the vapor pressure.

  Here, the “heterogeneous gas” is a different kind of gas that affects the vapor pressure in the tank and is unnecessary or inconvenient for the combustion of the internal combustion engine. The different gas includes a mixed gas such as air.

  Specifically, the second invention further includes a temperature detection unit that detects the temperature in the tank, and a vapor pressure detection unit that detects the vapor pressure in the tank, and the control unit includes the temperature in the tank and The theoretical value of the vapor pressure is estimated based on the temperature detected by the temperature detection unit with reference to the correlation with the vapor pressure, and the theoretical value of the vapor pressure and the actual measured value of the vapor pressure detected by the vapor pressure detection unit are obtained. A comparison is made to determine whether or not the different gas has been discharged from the tank based on whether or not the difference between the two is within a predetermined range. According to the above configuration, where the vapor pressure is a function of temperature, the theoretical value of the vapor pressure can be specified based on the temperature detected by the control unit. This is compared with the actually detected vapor pressure, and if the difference is within a predetermined range, it can be determined that the different gas has been exhausted.

  Here, the “predetermined range” is determined according to the influence on the vapor pressure when a certain amount of different gas remains, and cannot be ignored if there is a deviation of 2% from the theoretical value of the vapor pressure, for example. What is necessary is just to determine with the quantity of different types of gas remaining.

  As described above, according to the present invention, when the liquefied gas fuel is discharged, the liquefied gas fuel can be easily discharged by using a part of the circulation path, and when the liquefied gas fuel is filled, the foreign gas remaining in the tank is removed by the vapor pressure. Since it detects reliably based on a change, it is possible to improve the serviceability of the refilling work of liquefied gas fuel. Therefore, it is possible to reduce the service cost required for manual work.

Next, preferred embodiments for carrying out the present invention will be described with reference to the drawings.
(Embodiment 1)
In the embodiment of the present invention, the liquid gas fuel supply device of the present invention is applied to an LPG internal combustion engine system. FIG. 1 shows a block diagram of an LPG internal combustion engine system 1 in the present embodiment. As shown in FIG. 1, the present LPG internal combustion engine system 1 forms a circulation path 100 and is configured such that liquefied gas fuel circulates around a liquefied gas fuel tank 10.

  An internal combustion engine 30 including a pump 11, an emergency shutoff valve 12, and an injector 31, a check valve 14, a three-way valve 15, and a shutoff valve 16 along the flow direction of the liquefied gas during operation in the circulation path 100 from the liquefied gas fuel tank 10. The cooling device 19 and the pressure regulators 17 and 18 are provided.

  The liquefied gas fuel tank 10 has a cylinder structure suitable for storing liquefied gas fuel such as liquefied petroleum gas (LPG), liquefied natural gas (LNG), and compressed natural gas (CNG) of an internal combustion engine, and stores the liquefied gas fuel. A vapor pressure sensor 21 that is a vapor pressure detection unit that measures the vapor pressure of the gas and a temperature sensor 22 that is a temperature detection unit that measures the temperature of the liquefied gas fuel are provided.

  The pump 11 is a driving means of the present invention, and is configured to be able to forcibly circulate the liquefied gas fuel stored in the tank 10 in the circulation path 100. The emergency shut-off valve 12 is shut off when it is desired to immediately stop the gas supply to the internal combustion engine 30, such as when a gas leak has occurred. The internal combustion engine 30 is a power source having a plurality of cylinders (four cylinders in the drawing), and is configured such that a part of the liquefied gas fuel flowing through the circulation path 100 is injected into the cylinders by the injector 31. The check valve 14 is provided to prevent the liquefied gas fuel from flowing back through the circulation path 100.

  The three-way valve 15 and the shutoff valve 16 are in accordance with the present invention. The three-way valve 15 is provided at a connection point between the circulation path 100 and the pipe 26 from the discharge port 24. During normal operation, the circulation path 100 is released to block the flow path on the discharge port 24 side, The path 102 side is shut off when the liquefied gas fuel is discharged, and the liquefied gas fuel is discharged from the tank 10 to the discharge port 24 via the path 101, or the path 101 side is shut off when the liquefied gas fuel is filled. The liquefied gas fuel is supplied to the tank 10 from the discharge port 24 via the route. The shutoff valve 16 is configured to completely shut off the flow of the liquefied gas fuel on the path 102 side.

  The cooling device 19 cools a part of the liquefied gas fuel that circulates, and controls the temperature of the liquefied gas fuel so that the temperature in the tank 10 does not rise too much and the vapor pressure becomes too high. The pressure regulators 17 and 18 are for adjusting the fuel pressure in the fuel supply system (in the tank 10 and the circulation path 100) up to the internal combustion engine 30 to a constant value. The backflow of the liquefied gas fuel from the tank 10 is also prevented.

  A pipe 27 from the filling port 25 is inserted into the tank 10, and the shut-off valve 23 shuts off the supply of liquefied gas fuel through the pipe 27 and vents the gas in the tank 10. It has become.

  The control unit 20 is a so-called ECU (Electric Control Unit), and has a configuration as a computer device including a CPU, a memory (ROM or RAM), an I / O, a driver, and the like (not shown). The control unit 20 is configured to allow the LPG internal combustion engine system to function as the liquefied fuel supply device of the present invention by sequentially executing a computer program stored in advance in a ROM or the like. Note that the computer program may be supplied by a removable recording medium.

  The control unit 20 inputs the vapor pressure information from the pressure sensor 21 and the temperature information from the temperature sensor 22 as input information, and each drive signal to the emergency shutoff valve 12, the three-way valve 15, and the shutoff valves 16 and 23 as control information. Is configured to output.

  Further, the control unit 20 can be connected to the service tool 2 at the time of fuel replacement, and inputs the fuel discharge request signal Sre, the air bleeding request signal Sra, and the fuel filling request signal Srf from the service tool 2, and the service tool 2, a request completion signal Src is output.

  A plurality of paths 101 and 102 are provided between the liquefied gas fuel tank 10 and the discharge port 24 which is a fuel discharge means. The discharge of the liquefied gas fuel according to the present invention is performed in the path 101 including the pump 11.

  In the above configuration, the control unit 20 performs control according to the normal operation mode, the fuel extraction mode, or the fuel filling mode. The first embodiment relates to a fuel extraction mode, and the fuel filling mode will be described in a second embodiment.

  In the normal operation mode, the control unit 20 controls all the valves in the circulation path 100 to be opened so that the liquefied gas fuel in the tank 10 circulates in the circulation path 100. That is, the control unit 20 controls the three-way valve 15 so as to permit the circulation of the circulation path 100 while opening the emergency cutoff valve 12 and the cutoff valve 16 and blocking the path of the pipe 26 toward the discharge port 24. Then, the pump 11 is driven to forcibly send out the liquefied fuel gas in the tank 10, the required amount of fuel is supplied from the injector 31 to the internal combustion engine 30, the remaining liquefied gas fuel is circulated, and returned to the tank 10 again. . Gas fuel is injected from the injector 31 into the cylinder of the internal combustion engine 30 at a predetermined injection timing and injection amount, and burns to generate power. In the above processing, the liquefied gas fuel circulates in the circulation path 100 in the direction of the arrow indicated by the cross hatch in FIG.

  The fuel extraction mode is started when the service tool 2 is connected to the control unit 20 at a service station or the like and the fuel discharge request signal Sre is supplied from the service tool 2.

  The operation in the fuel extraction mode will be described with reference to the flowchart of FIG.

  In the normal operation mode (S10: NO), the control unit 20 performs a process for that purpose (S11).

  When maintenance is required, the vehicle equipped with the LPG internal combustion engine system 1 enters the service station. In extracting the liquefied gas fuel at the service station, first, an empty cylinder for fuel recovery is connected to the discharge port 24. Next, the service tool is connected to the control unit 20. At the start of fuel extraction, the service tool 2 notifies the fuel extraction request signal Sre.

  When the fuel extraction request signal Sre for entering the fuel extraction mode is received (S10: YES), the control unit 20 blocks the supply system path 102 (S12). That is, the control unit 20 distributes only the path 101 including the pump 11 in the circulation path 100 and blocks the path 102 not including the pump 11. That is, the control unit 20 controls the three-way valve 15 so as to open the emergency cutoff valve 12 and open the path of the pipe 26 toward the discharge port 24. Further, the shutoff valve 16 is shut off to close the path 102.

  Next, since it is a fuel extraction mode and flow rate control is not necessary, the control unit 20 drives the pump 11 at high speed to forcibly send out the liquefied fuel gas in the tank 10 and from the three-way valve 15 to the discharge port 24 via the pipe 26. Then, the liquefied gas fuel is discharged (S13). In the above processing, the liquefied gas fuel flows through the path 101 and the pipe 26 in the direction of the white arrow in FIG.

  The extraction operation is performed under the supervision of a service person. Since no request signal is output from the service tool 2 until the liquefied gas fuel is extracted from the tank 10 (S14: NO), the extraction operation is continued (S13). When the liquefied gas fuel is completely extracted from the tank 10, an operation end request is output from the service tool 2. When the operation end request is received (S14: YES), the control unit 20 ends the operation of the pump 11 and blocks the emergency shutoff valve 12 and the path of the three-way valve 15 toward the discharge port 24 for safety (S15). . Then, the process proceeds to other necessary processing (S16).

  According to the fuel supply apparatus of the first embodiment, the operation of extracting the liquefied gas fuel from the tank 10 which has been conventionally performed manually can be fully automated, and serviceability is remarkably improved. That is, it is not necessary for the service person to directly access the tank 10, and the fuel can be extracted with a simple preparation of connecting a cylinder from the discharge port 24. For this reason, it is possible to reduce the labor cost required for the work that requires manual labor, and it is possible to greatly reduce the service cost.

  In particular, according to the present embodiment, since the parts provided in the circulation path 100 of the fuel supply device used in the conventional LPG internal combustion engine system are used as they are for the fuel extraction process, the cost for the equipment is almost increased. There is also an advantage of not.

Further, according to the first embodiment, fuel can be extracted in a short time by high-speed operation of the pump 11.
(Embodiment 2)
The second embodiment of the present invention describes the fuel filling mode in the first embodiment. As a premise of the second embodiment, it is assumed that a data table in which the relationship between the temperature T of the liquefied gas fuel and the vapor pressure P is previously stored in the memory of the control unit 20.

  FIG. 4 shows a relationship diagram between the temperature T and the vapor pressure P when the liquefied gas fuel is LPG. As shown in FIG. 4, the increase rate of the vapor pressure P of the liquefied gas fuel increases as the temperature T increases. At this time, the corresponding vapor pressure curve differs depending on the type of liquefied gas fuel. FIG. 4 shows vapor pressure curves of the fuel Gc with a propane content of 20%, the fuel Gb with 50%, and the fuel Ga with 80% in LPG. That is, when a certain temperature T1 is specified, the corresponding vapor pressure P is Pa in the case of the fuel Ga, Pb in the case of the fuel Gb, and Pc in the case of the fuel Gc. In this embodiment, the type (for example, propane content) of the liquefied gas fuel stored in advance is specified.

  The fuel filling mode is started when the service tool 2 is connected to the control unit 20 at a service station or the like and a fuel filling request signal Srf is supplied from the service tool 2. The operation in the fuel filling mode will be described with reference to the flowchart of FIG.

  When necessary maintenance work such as replacement of tank-related parts is completed at the service station and the tank 10 is correctly installed in the LPG internal combustion engine system 1, the service tool 2 notifies the fuel filling request Srf. When the fuel filling request Srf is received (S20: YES), the control unit 20 performs a fuel filling process (S21). Specifically, the control unit 20 opens only the shut-off valve 23 necessary for fuel filling, and closes the other valves of the circulation path 100. Then, the liquefied gas fuel is filled into the tank 10 via the pipe 27 by supply from the outside. When the liquefied gas fuel is filled, an operation completion signal is notified from the control unit 20 to the service tool 2. In the above processing, the liquefied gas fuel flows through the pipe 27 in the direction of the filled arrow in FIG. At this time, when a different type of liquefied gas fuel (for example, LPG having a different propane ratio) is charged, information for specifying the type is input to the control unit 20 directly or via the service tool 2. Remembered.

  The fuel may be filled not via the filling port 25 but via the discharge port 24. In this case, the control unit 20 closes the cutoff valve 23 and the emergency cutoff valve 12 and controls the three-way valve 15 so that only the path 102 is opened. In this case, the liquefied gas fuel flows through the pipe 26 and the path 102 in the direction of the arrow shown by oblique hatching in FIG.

  When the fuel is replaced, especially when the tank is replaced, a lot of unnecessary gas, that is, air is mixed in the tank 10. If the operation is performed without removing this air, the air-fuel ratio in the internal combustion engine 30 may fluctuate, causing combustion problems. Therefore, after receiving the operation completion signal after fuel filling, the service tool 2 outputs an air bleeding request Sra to the control unit 20 (S22). When the control unit 20 receives the request, the control unit 20 opens only the valves necessary for bleeding and closes the other valves (S23). That is, the control unit 20 outputs a control signal that completely releases the shutoff valve 23. The control unit 20 also outputs a control signal that closes the passages 101 and 102 by closing the shutoff valve 12, the three-way valve 15, and the shutoff valve 16. In the above processing, air circulates in the pipe 27 in the direction of the horizontal stripe arrow in FIG.

  While the air is being discharged, the control unit 20 periodically obtains fuel temperature information from the temperature sensor 21 (S24), and refers to the type of liquefied gas fuel filled in the tank 10 with reference to the memory (for example, propane ratio). ) Is specified (S25). Next, the vapor pressure characteristic indicated by the data table in the memory is referred to (S26). Then, the theoretical vapor pressure P that the liquefied gas fuel should theoretically indicate with respect to the temperature T1 indicated by the fuel temperature information is specified (S27). For example, when the liquefied gas fuel is LPG having a propane ratio of 80%, Pa is acquired as the theoretical vapor pressure. In parallel, the control unit 20 acquires fuel vapor pressure information from the vapor pressure sensor 22, and obtains an actual measured value P of the vapor pressure (S28).

  Next, the control unit 20 compares the actual measurement value P of the vapor pressure with the theoretical value Pa of the vapor pressure specified in step S27 (S29). If the air is completely removed, the measured value P of the vapor pressure and the theoretical value Pa should almost coincide. On the other hand, if air still remains in the tank 10, a difference of a certain degree or more occurs between the actual measured value P and the theoretical value Pa of the vapor pressure. In the present embodiment, the fact that the difference between the measured value P of the vapor pressure and the theoretical value Pa is within 2% is used as a threshold value for determining whether or not the air has almost escaped. However, this threshold value can be changed in various ways.

  When the difference between the measured value P of the vapor pressure and the theoretical value Pa is more than 2% (S29: YES), the control unit 20 determines that the air has not completely escaped and continues the air venting operation. (S24-28). On the other hand, when the difference between the actual measured value P of the vapor pressure and the theoretical value Pa is within 2% (S29: NO), it is determined that the air bleed has ended, and the service tool 2 is notified of the completion of the air bleed operation. Notification is made (S30). And it transfers to another process, for example, normal operation mode (S31).

  As described above, according to the second embodiment, after the liquefied gas fuel is filled by the operation of the control unit 20, air, which is a different kind of gas that causes trouble in combustion of the internal combustion engine, is automatically discharged. At this time, since the completion of the air bleeding operation is determined based on whether or not the measured value P of the vapor pressure and the theoretical value Pa match, it is possible to perform air bleeding reliably.

In particular, according to the present embodiment, since the parts provided in the circulation path 100 of the fuel supply device used also in the conventional LPG internal combustion engine system are used as they are for the air bleeding process, the cost for the equipment is almost increased. There is also an advantage that there is no.
(Other embodiments)
The present invention can be applied with various modifications other than the above embodiment.

  For example, in each of the above-described embodiments, the operation instruction from the service tool 2 is performed. However, the controller 20 may be configured to directly instruct the fuel extraction, fuel filling, and air extraction operations.

  In the first embodiment, the control unit 20 may be configured to determine whether or not the liquefied gas fuel has completely drained from the tank 10 while referring to the measurement value of the vapor pressure sensor 22 and terminate the operation.

  In the second embodiment, the type of the liquefied gas fuel is input from the outside. However, if the type of the liquefied gas fuel, for example, the propane ratio does not change, the previously used vapor pressure characteristic curve is used as it is. You may comprise as follows.

  Also, among the types of liquefied gas fuel that may be used in the system, the liquefied gas fuel charged this time is the one whose theoretical value of vapor pressure is closest to the actual measured value of vapor pressure. It may be assumed that the completion of air bleeding is determined.

The block diagram of the liquefied gas fuel supply apparatus which concerns on embodiment. 5 is a flowchart for explaining a fuel discharge method in the LPG system according to the first embodiment. 9 is a flowchart for explaining a fuel discharge method in the LPG system system according to the second embodiment. The characteristic view which shows the relationship between the temperature and vapor pressure in a liquefied gas fuel.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... LPG system, 10 ... Liquefied gas fuel tank, 11 ... Pump (drive means), 12 ... Emergency shut-off valve, 14 ... Check valve, 15 ... Three-way valve, 16 ... Shut-off valve, 17/18 ... Pressure regulator, 19 DESCRIPTION OF SYMBOLS ... Cooling device, 20 ... Control part, 21 ... Steam pressure sensor (vapor pressure detection part), 22 ... Temperature sensor (temperature detection part), 23 ... Shut-off valve, 24 ... Discharge port (discharge means), 25 ... Filling port, 30 ... Internal combustion engine, 31 ... Injector, 100 ... Circulation path, 101, 102 ... Path, 26/27 ... Pipe

Claims (4)

A liquefied gas fuel supply device for supplying liquefied gas fuel from a tank to an internal combustion engine,
A circulation path for circulating the liquefied gas fuel stored in the tank and supplying the liquefied gas fuel to the internal combustion engine;
Drive means for forcibly circulating the liquefied gas fuel in the tank into the circulation path;
A discharge part provided in the circulation path, for discharging the liquefied gas fuel from the tank via at least a part of the circulation path;
And at least when the liquefied gas fuel is discharged, a blocking means for blocking the flow of the path that does not include the driving means among the plurality of paths connecting the discharge means and the tank in the circulation path. A liquefied gas fuel supply device. A control unit for controlling opening and closing of the blocking means;
The liquefied gas fuel supply apparatus according to claim 1, wherein the control unit closes the shut-off unit in accordance with an external discharge request for the liquefied gas fuel. A liquefied gas fuel supply device for supplying liquefied gas fuel from a tank to an internal combustion engine,
A gas discharge path for discharging different gas in the tank when the liquefied gas fuel is filled in the tank;
A controller that determines whether or not the different gas has been discharged from the tank based on a theoretical value of the vapor pressure in the tank and an actual measured value of the vapor pressure in the tank; A liquefied gas fuel supply device. A temperature detector for detecting the temperature in the tank;
A vapor pressure detector that detects the vapor pressure in the tank, and
The control unit estimates the theoretical value of the vapor pressure based on the temperature detected by the temperature detection unit with reference to the correlation between the temperature in the tank and the vapor pressure, and the theoretical value of the vapor pressure and the Comparing the actual value of the vapor pressure detected by the vapor pressure detector, and determining whether or not the different gas has been discharged from the tank based on whether or not the difference between the two is within a predetermined range. Item 4. The liquefied gas fuel supply device according to Item 3.

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