gas supply system

Abstract

The present invention provides a gas supply system that can perform gas leak checks in a gas supply system equipped with a check valve in the gas supply pipe. [Solution] The gas supply system includes a gas tank equipped with an automatic shut-off valve, a gas supply pipe connecting the gas tank and a gas utilization device, a seal, and a check valve provided in the gas supply pipe. The automatic shut-off valve opens when the gas supply pipe approaches the gas tank. The seal seals the connection space, including the automatic shut-off valve and the end of the gas supply pipe, when the distance between the automatic shut-off valve and the gas supply pipe is less than or equal to a threshold distance. The controller moves the gas tank back to a position where the automatic shut-off valve closes while maintaining the seal of the connection space, and outputs a gas leak signal indicating a gas leak other than at the check valve when the internal pressure of the gas supply pipe drops. Otherwise, the controller moves the gas tank back to a position where the seal of the connection space is released, and outputs a check valve malfunction signal indicating a gas leak at the check valve when the internal pressure of the gas supply pipe drops.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a gas supply system that supplies gas in a gas tank to a gas utilization device.

Background Art

[0002] Patent Document 1 discloses a gas supply system that includes a plurality of gas tanks and supplies gas from the gas tanks to a gas utilization device. In the gas supply system of Patent Document 1, a check valve is provided in a gas supply pipe that sends gas from the gas tank to the gas utilization device. Patent Document 1 discloses a check process for whether the check valve is normal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Gas leakage is also assumed to occur at locations other than the check valve. This specification provides a gas supply system that can perform both a check of the check valve and a check for gas leakage other than at the check valve.

Means for Solving the Problems

[0005] The gas supply system disclosed herein comprises a gas tank, a gas supply pipe, an actuator, a seal, a check valve, first and second pressure sensors, and a controller. The gas tank has an auto-close valve that opens when a push rod is pushed in and closes when the push rod is withdrawn. The gas tank is connected to the gas supply pipe. The gas supply pipe has a push rod at its end and guides the gas from the gas tank to a gas utilization device. The actuator moves the gas tank forward and backward relative to the gas supply pipe. The seal seals the connection space, including the opening of the auto-close valve and the end of the gas supply pipe, when the distance between the auto-close valve and the push rod is shorter than a predetermined threshold distance. A check valve is provided in the gas supply pipe to prevent backflow of gas. A first pressure sensor measures the pressure in the gas supply pipe upstream of the check valve. A second pressure sensor measures the pressure in the gas supply pipe downstream of the check valve.

[0006] When replacing a gas tank to which a gas supply pipe is connected and an automatic shut-off valve is open, the controller performs the following steps: (1) The controller moves the gas tank back to a position where the automatic shut-off valve is closed, while maintaining the sealing of the connection space. (2) The controller reduces a predetermined amount of gas from the gas supply pipe downstream of the check valve. The controller may also reduce the gas in the gas supply pipe by activating a gas utilization device, or by transferring the gas to a sub-tank for temporary gas storage. If the gas does not affect the environment, the controller may release a predetermined amount of gas into the atmosphere. (3) If the decrease in the measured value of the first or second pressure sensor before or after the first time has elapsed exceeds a predetermined first differential pressure threshold, the controller outputs a gas leak signal indicating that a gas leak has occurred elsewhere than the check valve. Step (3) checks whether or not a gas leak has occurred elsewhere than the check valve. (4) If the measurement values ​​of the first or second pressure sensor before and after the first time has elapsed does not exceed the first differential pressure threshold, the controller moves the gas tank back to a position where the sealing of the connection space is released. (5) If the decrease in the measurement value of the second pressure sensor before and after the second time has elapsed exceeds the second differential pressure threshold, the controller outputs a check valve abnormality signal indicating that a gas leak has occurred in the check valve, and moves the gas tank forward to a position where the connection space is sealed. The process in (5) checks whether or not a gas leak has occurred in the check valve. The gas supply system disclosed herein can perform both a check valve check and a gas leak check other than the check valve.

[0007] Details of the technology disclosed herein and further improvements are described in the following "Modes for Carrying Out the Invention". [Brief explanation of the drawing]

[0008] [Figure 1] This is a block diagram of the gas supply system in the embodiment. [Figure 2] Cross-sectional view of a gas tank and gas supply pipe (sealing position). [Figure 3]Cross-sectional view of the gas tank and gas supply pipe (valve open position). [Figure 4] This is a flowchart for the gas leak check procedure. [Figure 5] This is a flowchart of the gas leak check procedure (continuation of Figure 4). [Modes for carrying out the invention]

[0009] The gas supply system 2 of this embodiment will be described with reference to the drawings. Figure 1 shows a block diagram of the gas supply system 2. The gas supply system 2 of this embodiment is connected to a fuel cell 90, and the gas supply system 2 supplies hydrogen gas from the gas tank 10 to the fuel cell 90. The fuel cell 90 is an example of a gas utilization device to which the gas supply system 2 supplies gas.

[0010] The gas supply system 2 includes a gas tank 10, a gas supply pipe 30, a push rod 35, an actuator 19, a first pressure sensor 41, a second pressure sensor 42, a check valve 31, a controller 50, and a display device 51.

[0011] The gas tank 10 is filled with high-pressure hydrogen gas. The gas tank 10 and the fuel cell 90 are connected by a gas supply pipe 30. The gas supply pipe 30 guides the hydrogen gas from the gas tank 10 to the fuel cell 90. A check valve 31 and a pressure reducing valve 32 are connected to the gas supply pipe 30. The pressure reducing valve 32 is located downstream of the check valve 31. Here, "downstream" means the side of the gas supply pipe 30 closer to the fuel cell 90 (gas utilization device), and "upstream" means the side closer to the gas tank 10.

[0012] The pressure reducing valve 32 reduces the pressure of the hydrogen gas supplied from the gas tank 10 to a pressure suitable for the operation of the fuel cell 90. In other words, the gas pressure suitable for the fuel cell 90 is lower than the gas pressure supplied from the gas tank 10.

[0013] The check valve 31 allows gas to pass from upstream to downstream, but prevents gas from flowing from downstream to upstream. The check valve 31 also prevents hydrogen gas from leaking to the outside from downstream of the check valve 31 in the event of a gas leak at the connection point between the gas tank 10 and the gas supply pipe 30.

[0014] The first pressure sensor 41 measures the pressure inside the gas supply pipe 30 upstream of the check valve 31. If the gas tank 10 is connected to the gas supply pipe 30, the value measured by the first pressure sensor 41 is approximately equal to the internal pressure of the gas tank 10 (the value measured by the first pressure sensor 41 will be lower than the internal pressure of the tank due to pressure losses such as the automatic shut-off valve 20 described later).

[0015] The second pressure sensor 42 measures the pressure in the gas supply pipe 30 downstream of the check valve 31. While gas is being supplied from the gas tank 10, the value measured by the second pressure sensor 42 is approximately equal to the value measured by the first pressure sensor 41 (the value measured by the second pressure sensor 42 will be lower than the value measured by the first pressure sensor 41 due to pressure loss from the check valve 31, etc.).

[0016] The lower part of Figure 1 shows a cross-sectional view of the valve 11 of the gas tank 10 and the end of the gas supply pipe 30. The valve 11 of the gas tank 10 is equipped with an automatic shut-off valve 20. The automatic shut-off valve 20 includes a sleeve 21, a valve body 22, and a spring 23. The sleeve 21 is mounted inside the valve 11. The valve body 22 is positioned adjacent to the sleeve 21 inside the tank. The spring 23 presses the valve body 22 against the opening of the sleeve 21 (the opening that is open inside the tank) from the inside of the tank. The opposite end of the spring 23 is supported by the inner wall of the tank.

[0017] The force of the spring 23 causes the valve body 22 to tightly seal against the opening of the sleeve 21. While the valve body 22 is tightly sealed against the opening of the sleeve 21, the automatic shut-off valve 20 remains closed. When the valve body 22 is pushed inward from the outside of the tank, the automatic shut-off valve 20 opens. When the load on the valve body 22 is removed, the force of the spring 23 causes the valve body 22 to tightly seal against the opening of the sleeve 21 again, and the automatic shut-off valve 20 closes.

[0018] A push rod 35 is provided at the tip of the gas supply pipe 30. The push rod 35 is fixed to the tip of the gas supply pipe 30 by a rod support 36. The rod support 36 is provided with a hole through which gas can flow from the gas tank 10 into the gas supply pipe 30.

[0019] When the gas tank 10 is set in the gas supply system 2, the push rod 35 at the tip of the gas supply pipe 30 faces the base 11. The actuator 19 moves the gas tank 10. The actuator 19 moves the gas tank 10 closer to or farther away from the gas supply pipe 30. More specifically, the actuator 19 moves the automatic closing valve 20 closer to or farther away from the tip of the gas supply pipe 30 (i.e., the push rod 35). The cross-sectional view of FIG. 1 shows a state where the push rod 35 is separated from the automatic closing valve 20.

[0020] The actuator 19 moves the gas tank 10 forward and backward relative to the tip of the gas supply pipe 30. For the sake of explanation, when the gas tank 10 approaches the gas supply pipe 30, it is called "forward movement", and when the gas tank 10 moves away from the gas supply pipe 30, it is called "backward movement". The actuator may move the gas supply pipe 30 forward and backward with respect to the gas tank 10.

[0021] A sealing 12 is arranged inside the base 11. When the tip of the gas supply pipe 30 (push rod 35) approaches the automatic closing valve 20, the outer periphery of the gas supply pipe 30 contacts the sealing 12, and the space including the opening of the automatic closing valve 20 (the opening facing the outside of the gas tank 10) and the tip of the gas supply pipe 30 is sealed. The space including the opening of the automatic closing valve 20 and the tip of the gas supply pipe 30 is referred to as the connection space S for convenience. More precisely, the connection space S is inside the base 11 and refers to the space including the opening of the automatic closing valve 20 and the tip of the gas supply pipe 30. In the cross-sectional view of FIG. 1, the push rod 35 is separated from the automatic closing valve 20, and a gap G is secured between the tip of the gas supply pipe 30 and the sealing 12. In this state, the connection space S is not sealed from the outside world.

[0022] Figure 2 shows a cross-section when the tip of the gas supply pipe 30 contacts the seal 12. When the distance between the push rod 35 and the automatic closing valve 20 reaches L1, the seal 12 contacts the outer periphery of the gas supply pipe 30, and the connection space S is sealed. In other words, when the distance between the push rod 35 and the valve body 22 of the automatic closing valve 20 becomes shorter than L1, the connection space S is blocked from the outside world. When the distance between the push rod 35 and the valve body 22 is L1, the automatic closing valve 20 remains closed. The distance L1 may be referred to as a threshold distance.

[0023] The phantom line in Figure 2 shows the state where the gas tank 10 has advanced until the valve body 22 contacts the tip of the push rod 35. When the gas tank 10 advances further than the phantom line, the push rod 35 pushes open the automatic closing valve 20. Figure 3 is a cross-sectional view when the gas tank 10 has advanced until the automatic closing valve 20 is opened. The thick arrow line A indicates the gas flow. While the automatic closing valve 20 is open, the hydrogen gas in the gas tank 10 flows through the connection space S and into the gas supply pipe 30. Since the connection space S is sealed by the seal 12, the hydrogen gas does not leak to the outside.

[0024] The gas in the gas tank 10 passes through the opened automatic closing valve 20, through the hole in the rod support 36, and flows into the gas supply pipe 30. For the sake of convenience in explanation, the position of the gas tank 10 when the connection space S is sealed but the automatic closing valve 20 is closed is referred to as the sealing position, and the position of the gas tank 10 when the connection space S is sealed and the automatic closing valve 20 is open is referred to as the valve opening position. Figure 2 is a cross-sectional view at the sealing position, and Figure 3 is a cross-sectional view at the valve opening position. The sealing position is the case where the distance between the push rod 35 and the valve body 22 of the automatic closing valve 20 is less than or equal to L1 and greater than zero. Also in the valve opening position, the seal 12 contacts the outer periphery of the gas supply pipe 30, and the connection space S remains sealed.

[0025] Also, as shown in Figure 1, the position of the gas tank 10 when the sealing of the connection space S is released and the connection space S communicates with the outside world is referred to as the detachment position.

[0026] When a new gas tank 10 is set in the actuator 19, the controller 50 (see Figure 1) moves the gas tank 10 forward to the open valve position. The automatic shut-off valve 20 opens, and the gas from the gas tank 10 flows through the check valve 31 and the pressure reducing valve 32 to the fuel cell 90. The fuel cell 90 becomes operational. The controller 50 activates the fuel cell 90.

[0027] When the amount of gas remaining in gas tank 10 decreases, it becomes necessary to replace gas tank 10. If there is a malfunction in the check valve 31 when removing the old gas tank 10, hydrogen gas may leak to the outside. Therefore, prior to retracting gas tank 10 to the detachment position, the controller 50 performs a gas leak check. In other words, the controller 50 performs a gas leak check when replacing gas tank 10 to which the gas supply pipe 30 is connected and the automatic shut-off valve 20 is open.

[0028] Figures 4 and 5 show a flowchart of the gas leak check process performed by the controller 50. First, the controller 50 controls the actuator 19 to move the gas tank 10 to the sealing position (step S12). In the sealing position, the automatic shut-off valve 20 is closed, but the connection space S remains sealed.

[0029] Next, the controller 50 reduces a predetermined amount of gas in the gas supply pipe 30 downstream of the check valve 31 (step S13). The controller 50 may reduce the gas in the gas supply pipe 30 by operating the fuel cell 90, or it may reduce the gas in the gas supply pipe 30 by transferring some of the gas in the gas supply pipe 30 to a reserve tank (not shown). Alternatively, if the gas does not affect the environment, the controller 50 may release a predetermined amount of gas in the gas supply pipe 30 into the atmosphere.

[0030] When the gas in the gas supply pipe 30 is reduced downstream of the check valve 31, the pressure in the gas supply pipe 30 downstream of the check valve 31 falls below the pressure upstream of the check valve 31. The gas upstream of the check valve 31 moves downstream through the check valve 31, and the pressure upstream and downstream of the check valve 31 become equal. In other words, the measured values ​​of the first pressure sensor 41 and the second pressure sensor 42 become equal.

[0031] Next, the controller 50 waits for a predetermined first hour (step S14). During this time, the controller 50 stores the measured values ​​of the pressure sensors 41 and 42 before and after the first hour has elapsed (step S14). For the sake of explanation, the measured value of the first pressure sensor 41 (i.e., the pressure in the gas supply pipe 30 upstream of the check valve 31) will be referred to as the first measured value, and the measured value of the second pressure sensor 42 (i.e., the pressure in the gas supply pipe 30 downstream of the check valve 31) will be referred to as the second measured value.

[0032] After the first hour has elapsed, the controller 50 checks whether the decrease in the first measured value before and after the first hour, or the decrease in the second measured value before and after the first hour, exceeds a predetermined threshold (first differential pressure threshold) (step S15). If the decrease in the first or second measured value before and after the first hour exceeds the first differential pressure threshold (step S15: YES), this means that gas is leaking to the outside from the gas supply pipe 30. At this time, the controller 50 outputs a signal (gas leak signal) to the display device 51 indicating that a gas leak is occurring other than from the check valve 31, and stops the gas supply system 2 and the fuel cell 90 (steps S15: YES, S16, S17). Upon receiving the gas leak signal, the display device 51 lights up a warning lamp (or emits a warning sound) indicating that a gas leak is occurring from the gas supply pipe 30 other than from the check valve 31.

[0033] If the decrease in the first or second measured value around the time of the first hour does not exceed the first differential pressure threshold (step S15: NO), it is determined that no gas leak has occurred anywhere other than the check valve 31. At this point, however, it is unknown whether or not there is a malfunction in the check valve 31.

[0034] If the judgment in step S15 is "NO", the controller 50 moves the gas tank 10 to the deactivation position (step S21). In the deactivation position, the seal on the connection space S is released, and the connection space S is connected to the outside world. At this time, the first measurement value becomes equal to atmospheric pressure.

[0035] Next, the controller 50 waits for a predetermined second time (step S22). During this time, the controller 50 stores the second measurement values ​​(measurements from the second pressure sensor 42) before and after the second time has elapsed (step S22).

[0036] After the second time has elapsed, the controller 50 checks whether the decrease in the second measured value before and after the second time has elapsed exceeds a predetermined threshold (second differential pressure threshold) (step S23). If the decrease in the second measured value before and after the second time has elapsed exceeds the second differential pressure threshold (step S23: YES), this means that gas is flowing from the downstream side to the upstream side of the check valve 31, and gas is leaking from the connection space S to the outside. In other words, it means that there is a malfunction in the check valve 31. At this time, the controller 50 outputs a signal (check valve malfunction signal) to the display device 51 indicating that there is a gas leak in the check valve 31 (step S25). Upon receiving the check valve malfunction signal, the display device 51 displays a message indicating that there is a malfunction in the check valve 31 (or emits a warning sound).

[0037] Furthermore, the controller 50 moves the gas tank 10 to the sealing position (step S26). By moving the gas tank 10 to the sealing position, the connection space S is sealed. Therefore, even if a malfunction occurs in the check valve 31, the gas leak will stop. Finally, the controller 50 shuts down the system (step S27).

[0038] If the branching determination in step S15 is "NO", it is confirmed that no gas leaks are occurring anywhere other than the check valve 31. Therefore, if the decrease in the second measured value in step S23 exceeds the second differential pressure threshold, it is determined that the cause is a malfunction of the check valve 31.

[0039] If the decrease in the second measured value in step S23 falls below the second differential pressure threshold, the check valve 31 is also determined to be functioning normally. In this case, the controller 50 outputs a signal (normal signal) to the display device 51 indicating that there is no gas leak, including from the check valve 31 (steps S23: NO, S24). Upon receiving the normal signal, the display device 51 displays a message indicating that there is no gas leak in the gas supply system 2 and that the gas tank 10 can be replaced. Upon seeing the message indicating that the gas tank 10 can be replaced, the staff replaces the gas tank 10, which is in the detached position, with a new gas tank.

[0040] The gas supply system 2 of the embodiment can perform both a check of the check valve 31 and a gas leak check at locations other than the check valve.

[0041] The following are points to note regarding the technology described in the embodiment. The gas leak check process performed by the controller 50 of the gas supply system 2 is as follows: When replacing a gas tank 10 to which the gas supply pipe 30 is connected and the automatic shut-off valve 20 is open, the controller 50 performs the following process: (1) The controller 50 moves the gas tank 10 back to the position where the automatic shut-off valve is closed (sealing position) while maintaining the sealing of the connection space S (step S12). (2) The controller 50 reduces a predetermined amount of gas from the gas supply pipe 30 downstream of the check valve 31 (step S13). Subsequently, the controller 50 waits for a first hour (step S14). At this time, the controller stores the first and second measured values ​​before and after the first hour has elapsed (step S14). (3) If the controller 50 determines that the amount of decrease in the measured value of the first pressure sensor 41 or the second pressure sensor 42 before or after the first time has elapsed exceeds a predetermined first differential pressure threshold, it outputs a gas leak signal indicating that a gas leak has occurred at a location other than the check valve (step S15: YES, S16). The process in (3) checks whether or not a gas leak has occurred at a location other than the check valve.

[0042] (4) If the decrease in the measured value of the first or second pressure sensor before and after the first time has elapsed does not exceed the first differential pressure threshold, the controller 50 moves the gas tank 10 backward to the position where the sealing of the connection space S is released (detachment position) (step S15: NO, S21). The controller 50 then waits for a second time (step S22). At this time, the controller 50 stores the second measured value before and after the second time has elapsed (step S22). (5) If the decrease in the measured value of the second pressure sensor 42 before and after the second time has elapsed exceeds the second differential pressure threshold, the controller 50 outputs a check valve abnormality signal indicating that a gas leak has occurred in the check valve 31, and moves the gas tank 10 forward to the position where the connection space S is sealed (sealing position) (step S23: YES, S25, S26). The process in (5) checks whether or not a gas leak has occurred in the check valve 31. The gas supply system 2 of the embodiment can perform both a check of the check valve 31 and a gas leak check at locations other than the check valve.

[0043] The first and second hours can be as short as a few tens of seconds to a few minutes. The first and second hours are set to the time when, in the event of a gas leak, a significant drop in pressure inside the gas supply pipe 30 is expected to occur.

[0044] Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or drawings exhibit technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives itself constitutes technical usefulness. [Explanation of Symbols]

[0045] 2: Gas supply system 10: Gas tank 11: Valve 12: Sealing 19: Actuator 20: Automatic shut-off valve 21: Sleeve 22: Valve body 23: Spring 30: Gas supply pipe 31: Check valve 32: Pressure reducing valve 35: Push rod 36: Rod support 41: First pressure sensor 42: Second pressure sensor 50: Controller 51: Display device 90: Fuel cell

Claims

[Claim 1] A gas tank having an automatic shut-off valve that opens when a push rod is pushed in and closes when the push rod is removed, A gas supply pipe to which the gas tank is connected, the gas supply pipe having the push rod at its tip, and which guides the gas from the gas tank to a gas utilization device, An actuator that moves the gas tank forward and backward relative to the gas supply pipe, A sealing mechanism that seals the connection space including the opening of the automatic shut-off valve and the tip of the gas supply pipe when the distance between the automatic shut-off valve and the push rod is shorter than a predetermined threshold distance, The aforementioned gas supply pipe is equipped with a check valve that prevents backflow of gas, A first pressure sensor is located upstream of the check valve and measures the pressure inside the gas supply pipe. A second pressure sensor, located downstream of the check valve, measures the pressure inside the gas supply pipe. Controller and It is equipped with, When replacing the gas tank to which the gas supply pipe is connected and the automatic shut-off valve is open, the controller While maintaining the sealing of the connection space, the gas tank is moved back to a position where the automatic shut-off valve closes. Downstream of the aforementioned check valve, a predetermined amount of gas is reduced from the gas supply pipe. If the decrease in the measured value of the first pressure sensor or the second pressure sensor before or after the first time has elapsed exceeds a predetermined first differential pressure threshold, a gas leak signal is output indicating that a gas leak is occurring at a location other than the check valve. If the decrease in the measured value of the first pressure sensor or the second pressure sensor before and after the elapsed time does not exceed the first differential pressure threshold, the gas tank is moved back to a position where the seal of the connection space is released. If the decrease in the measured value of the second pressure sensor before and after the second time has elapsed exceeds a predetermined second differential pressure threshold, a check valve abnormality signal indicating that a gas leak is occurring in the check valve is output, and the gas tank is advanced to a position where the connection space is sealed. Gas supply system.

Images