gas supply system

Abstract

This invention provides a gas supply system that can check the quality of the automatic shut-off valve (main shut-off valve) of a gas tank. [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, and a seal. 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. After closing the automatic shut-off valve, the controller outputs a gas venting failure signal if a threshold amount of gas is not released from the gas supply pipe within a threshold time. If the controller is able to release a threshold amount of gas within a threshold time, it calculates an estimated value of the pressure in the gas supply pipe after the gas has been released. If the pressure sensor reading after the threshold amount of gas has been released is higher than the estimated value, the controller outputs a shut-off valve malfunction signal indicating a malfunction of the automatic shut-off valve.

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 supplies gas from a gas tank to a gas utilization device. Before removing the gas tank from the system, the gas supply system of Patent Document 1 checks whether the main shut-off valve of the gas tank is securely closed. When checking the condition of the main shut-off valve, the gas supply system consumes a predetermined amount of gas in the gas supply pipe connecting the gas tank and the gas utilization device and reduces the internal pressure of the gas supply pipe.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the case of the gas supply system of Patent Document 1, if the gas in the gas supply pipe cannot actually be consumed when checking the main shut-off valve, the pressure of the gas supply pipe may not decrease, and there is a risk that the check of the main shut-off valve may not be correctly performed. This specification provides a gas supply system that can more reliably check the condition of the main shut-off valve.

Means for Solving the Problems

[0005] The gas supply system disclosed herein comprises a gas tank with an automatic shut-off valve, a gas supply pipe, an actuator, a seal, a pressure sensor, and a controller. The automatic shut-off valve of the gas tank opens when a push rod is pushed in and closes when the push rod is removed. The automatic shut-off valve acts as the main shut-off valve of the gas tank. 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 automatic shut-off valve and the end 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 pressure sensor measures the pressure in the gas supply pipe.

[0006] The controller performs the following shut-off valve check process while the gas tank is connected to the gas supply pipe: (1) The controller retracts the gas tank to a position where the automatic shut-off valve closes while maintaining the sealing of the connection space. (2) The controller acquires the measured value (first measured value) from the pressure sensor. (3) The controller removes a predetermined threshold amount of gas from the gas supply pipe within a predetermined threshold time, and if it fails to remove the threshold amount of gas from the gas supply pipe within the threshold time, it outputs a gas removal failure signal indicating a gas removal failure. Process (3) allows confirmation that the threshold amount of gas has been removed from the gas supply pipe.

[0007] (4) If the threshold amount of gas can be released within the threshold time, the controller calculates an estimated value of the pressure in the gas supply pipe after the threshold amount of gas has been released from the first measured value and the threshold amount. (5) The controller obtains the measured value of the pressure sensor (second measured value) after the threshold amount of gas has been released. (6) If the second measured value is higher than the estimated value, the controller outputs a shut-off valve malfunction signal indicating a malfunction of the automatic shut-off valve. The gas supply system disclosed herein can more reliably check the condition of the automatic shut-off valve (main shut-off valve).

[0008] 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]

[0009] [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 valve shut-off check process. [Figure 5] This is a flowchart of the valve shut-off check process (continuation of Figure 4). [Modes for carrying out the invention]

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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 measurement value of the first pressure sensor 41 when no gas is flowing is equal to the internal pressure of the gas tank 10.

[0016] 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.). When the gas flow stops, the value measured by the second pressure sensor 42 becomes equal to the value measured by the first pressure sensor 41.

[0017] 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.

[0018] By the force of the spring 23, the valve body 22 adheres closely to the opening of the sleeve 21. While the valve body 22 is adhering closely to the opening of the sleeve 21, the automatic closing valve 20 is closed. When the valve body 22 is pushed from the outside to the inside of the tank, the automatic closing valve 20 opens. When the load on the valve body 22 disappears, the valve body 22 adheres closely to the opening of the sleeve 21 again by the force of the spring 23, and the automatic closing valve 20 closes.

[0019] 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, and gas can flow from the gas tank 10 into the gas supply pipe 30 through the hole.

[0020] 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 the state where the push rod 35 is separated from the automatic closing valve 20.

[0021] 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, the case where the gas tank 10 approaches the gas supply pipe 30 is referred to as "forward movement", and the case where the gas tank 10 moves away from the gas supply pipe 30 is referred to as "backward movement". The actuator may move the gas supply pipe 30 forward and backward relative to the gas tank 10.

[0022] A sealing 12 is arranged inside the base 11. When the tip (push rod 35) of the gas supply pipe 30 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.

[0023] FIG. 2 shows a cross-section when the tip of the gas supply pipe 30 contacts the sealing 12. When the distance between the push rod 35 and the automatic closing valve 20 reaches L1, the sealing 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. 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 the threshold distance.

[0024] The phantom line in FIG. 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. FIG. 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 sealing 12, the hydrogen gas does not leak to the outside.

[0025] The gas in the gas tank 10 passes through the open automatic shut-off valve 20, through the hole in the rod support 36, and flows into the gas supply pipe 30. For the sake of explanation, the position of the gas tank 10 when the connection space S is sealed but the automatic shut-off valve 20 is closed is called the sealing position, and the position of the gas tank 10 when the connection space S is sealed and the automatic shut-off valve 20 is open is called the open valve position. Figure 2 is a cross-sectional view in the sealing position, and Figure 3 is a cross-sectional view in the open valve position. The sealing position is when the distance between the push rod 35 and the valve body 22 of the automatic shut-off valve 20 is L1 or less and greater than zero. Even in the open valve position, the seal 12 is in contact with the outer circumference of the gas supply pipe 30, and the connection space S remains sealed.

[0026] Furthermore, the position of the gas tank 10 when it has retracted and the sealing of the connection space S has been released, allowing the connection space S to be open to the outside world, is referred to as the detachment position (see Figure 1).

[0027] 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.

[0028] When the amount of gas remaining in the gas tank 10 decreases, the gas tank 10 needs to be replaced. If there is a malfunction in the automatic shut-off valve 20 when removing the old gas tank 10, hydrogen gas may leak to the outside. Therefore, prior to retracting the gas tank 10 to the detachment position, the controller 50 performs a shut-off valve check process. Specifically, when the amount of gas remaining in the gas tank 10, to which the gas supply pipe 30 is connected and the automatic shut-off valve 20 is open, falls below a predetermined threshold amount, the controller 50 performs a shut-off valve check process to check whether the automatic shut-off valve 20 is functioning correctly.

[0029] Figures 4 and 5 show the flowchart of the valve shut-off 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.

[0030] Next, the controller 50 acquires the measurement value from the first pressure sensor 41 (step S13). The measurement value from the first pressure sensor 41 refers to the pressure inside the gas supply pipe 30. Hereafter, the measurement value from the first pressure sensor 41 acquired in step S13 will be referred to as the first measurement value.

[0031] Next, the controller 50 removes a predetermined threshold amount of gas from the gas supply pipe 30. The controller 50 removes the gas from the gas supply pipe 30 by operating the fuel cell 90 to consume the gas (hydrogen gas) in the gas supply pipe 30. At this time, the controller 50 stores the amount of electricity (power generation) generated by the fuel cell 90. There is a certain relationship between the power generation of the fuel cell 90 and the amount of hydrogen gas consumed by the fuel cell 90 (mass of consumed hydrogen gas). The controller 50 uses this relationship to estimate the amount of gas consumed (mass of consumed hydrogen gas) from the power generation of the fuel cell 90 (step S15). The amount of gas consumed by the fuel cell 90 is equal to the amount of gas removed from the gas supply pipe 30. The controller 50 operates the fuel cell 90 until the amount of gas removed from the gas supply pipe 30 reaches a threshold amount (step S16: NO, S17: NO, S14, or step S16: YES, S21).

[0032] On the other hand, if the amount of gas removed does not reach a threshold amount even after a predetermined threshold time has elapsed since the start of gas removal, the controller 50 outputs a gas removal failure signal to the display device 51 indicating that it was not possible to remove the threshold amount of gas from the gas supply pipe 30 (steps S17: YES, S18). Upon receiving the gas removal failure signal, the display device 51 lights up a warning lamp (or emits a warning sound) indicating that it was not possible to remove the threshold amount of gas from the gas supply pipe 30. For example, if there is a malfunction in the check valve 31, gas will flow from downstream to upstream of the check valve 31, which will take time to remove the gas. As a result, it may not be possible to remove the threshold amount of gas within the threshold time. Finally, the controller 50 stops the gas supply system 2 and the fuel cell 90 (step S19).

[0033] If a threshold amount of gas escapes from the gas supply pipe 30 before the threshold time has elapsed, the controller 50 shuts down the fuel cell 90 (step S16: YES, S21).

[0034] Next, the controller 50 calculates an estimated value of the pressure inside the gas supply pipe 30 after the threshold amount of gas has been released (step S22). The controller 50 calculates an estimated value of the pressure inside the gas supply pipe 30 after the threshold amount of gas has been released from the first measured value (i.e., the internal pressure of the gas supply pipe 30 before the threshold amount of gas has been released), the threshold amount (i.e., the amount of gas released from the gas supply pipe 30), and the temperature inside the gas supply pipe 30. Although not shown in the diagram, the gas supply system 2 is equipped with a temperature sensor that measures the temperature inside the gas supply pipe 30. As mentioned earlier, the threshold amount refers to the mass of hydrogen gas. Since the capacity of the gas supply pipe 30 is known, the pressure inside the gas supply pipe 30 after the threshold amount of gas has been released can be calculated from the above parameters. The first measured value is equal to the pressure inside the gas tank 10. The estimated value of the pressure inside the gas supply pipe 30 after the threshold amount of gas has been released will be lower than the first measured value.

[0035] The controller 50 acquires the measurement value of the first pressure sensor 41 again (i.e., the pressure in the gas supply pipe 30 after the threshold amount of gas has been released) (step S23). Hereinafter, the measurement value of the first pressure sensor 41 after the threshold amount of gas has been released will be referred to as the second measurement value.

[0036] The controller 50 compares the second measured value with the estimated value calculated in step S22 (step S24). If there is a malfunction in the automatic shut-off valve 20 and gas from the gas tank 10 is leaking into the gas supply pipe 30, the second measured value will be higher than the estimated value (step S24: YES). In that case, the controller 50 outputs a shut-off valve malfunction signal indicating that there is a malfunction in the automatic shut-off valve 20 (step S25). The display device 51, upon receiving the shut-off valve malfunction signal, lights up a warning lamp (or emits a warning sound) indicating that there is a malfunction in the automatic shut-off valve 20. The controller 50 then stops the gas supply system 2 (step S26).

[0037] If the decision in step S24 is NO, it means that the second measured value is equal to the estimated value. The second measured value being equal to the estimated value means that the automatic shut-off valve 20 is properly closed. In this case, the controller 50 moves the gas tank 10 to the detachment position and sends a tank replacement permission signal to the display device 51 (steps S27, S28). Upon receiving the tank replacement permission signal, the display device 51 displays a message indicating that the old gas tank 10 may be replaced with a new gas tank 10. Upon seeing this message, the operator removes the old gas tank 10 from the actuator 19 and sets the new gas tank 10 into the actuator 19.

[0038] The automatic shut-off valve 20 of the gas tank 10 corresponds to the main shut-off valve of the gas tank 10. The gas supply system 2 performs the above shut-off valve check process before retracting the gas tank 10 to the detachment position. Steps S22 to S24 in Figure 5 are the main processes for determining whether the automatic shut-off valve 20 is properly closed. Prior to these processes, the controller 50 checks whether a threshold amount of gas has been correctly released from the gas supply pipe 30 within the threshold time (steps S13 to S17). By performing these processes, the gas supply system 2 can more reliably check the condition of the automatic shut-off valve 20 (the main shut-off valve of the gas tank 10).

[0039] The following are points to note regarding the technology described in the embodiment. The controller 50 can use the actuator 19 to move the gas tank 10 to one of the following positions: (1) the position of the gas tank 10 when the connection space S is sealed and the automatic shut-off valve 20 is open (open valve position); (2) the position of the gas tank 10 when the connection space S is sealed but the automatic shut-off valve 20 is closed (sealed position); or the position of the gas tank 10 when the sealing of the connection space S is released and the connection space S is open to the outside world (deactivation position).

[0040] Prior to moving the gas tank 10, which was in the open position and supplying gas to the gas utilization device, to the detachment position, the controller 50 performs the following valve shut-off check process: (1) The controller 50 retracts the gas tank 10 to the position where the automatic shut-off valve 20 closes (i.e., the sealing position) while maintaining the sealing of the connection space S. (2) The controller 50 acquires the measured value (first measured value) from the first pressure sensor 41. (3) The controller 50 removes a predetermined threshold amount of gas from the gas supply pipe 30 within a predetermined threshold time, and outputs a gas removal failure signal indicating a gas removal failure if it is not possible to remove the threshold amount of gas within the threshold time. (4) If the controller 50 is able to remove the threshold amount of gas within the threshold time, it calculates an estimated value of the pressure in the gas supply pipe 30 after removing the threshold amount of gas from the first measured value and the threshold amount. The threshold amount is expressed as the mass of the gas. (5) The controller 50 acquires the measured value (second measured value) from the first pressure sensor 41 after removing the threshold amount of gas. (6) If the second measured value is higher than the estimated value, the controller 50 outputs a shut-off valve malfunction signal indicating a malfunction of the automatic shut-off valve 20.

[0041] Furthermore, if the second measured value is equal to the estimated value, the controller 50 moves the gas tank 10 to a position where the seal of the connection space S is released (i.e., the detachment position).

[0042] One example of a method for removing a threshold amount of gas from the gas supply pipe 30 is to operate a fuel cell 90, which is a gas utilization device, to consume the hydrogen gas filling the gas supply pipe 30. At this time, the controller 50 measures the amount of power generated by the fuel cell 90 and calculates the amount of gas to be removed from the gas supply pipe 30 based on the amount of power generated.

[0043] The gas supply system 2 may remove the gas from the gas supply pipe 30 by transferring the gas from the gas supply pipe 30 to another tank (auxiliary tank). The amount of gas transferred to the auxiliary tank corresponds to the threshold amount. In this case, the threshold amount is expressed as the volume of gas. The volume of the gas supply pipe 30 is also known. The controller 50 can calculate an estimated value of the pressure inside the gas supply pipe 30 after removing the threshold amount of gas from the volume of the gas supply pipe 30 (i.e., the threshold amount), the volume of the auxiliary tank, and the first measured value.

[0044] The signals output by the controller 50 (gas venting failure signal / close valve malfunction signal) may be sent to devices other than the display device 51. For example, these signals may be sent to a controller that performs the necessary actions when an abnormality occurs. The tank replacement permission signal may also be sent to a portable terminal of the staff member responsible for replacing the tank.

[0045] 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]

[0046] 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

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, A pressure sensor for measuring the pressure inside the gas supply pipe, Controller and It is equipped with, The aforementioned 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. The first measurement value of the pressure sensor is acquired, A predetermined threshold amount of gas is removed from the gas supply pipe within a predetermined threshold time, and if the threshold amount of gas cannot be removed within the threshold time, a gas removal failure signal is output to indicate a gas removal failure. If the threshold amount of gas can be released within the threshold time, an estimated value of the pressure in the gas supply pipe after the threshold amount of gas has been released is calculated from the first measured value and the threshold amount. After releasing the aforementioned threshold amount of gas, the second measurement value of the pressure sensor is obtained. If the second measured value is higher than the estimated value, a shut-off valve malfunction signal indicating an abnormality of the automatic shut-off valve is output. Gas supply system.

2. The gas supply system according to claim 1, wherein the controller moves the gas tank to a position where the sealing of the connection space is released when the second measured value is equal to the estimated value.

3. The aforementioned gas tank is filled with hydrogen gas. The gas utilization device is a fuel cell that generates electricity using hydrogen gas from the gas tank, The gas supply system according to claim 1 or 2, wherein the controller extracts gas from the gas supply pipe by generating electricity with the fuel cell, and calculates the amount of gas extracted from the gas supply pipe from the amount of electricity generated by the fuel cell.

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