GAS SUPPLY SYSTEM

Abstract

As a gas supply pipe approaches a gas tank in a gas supply system, a self-closing valve opens. A seal closes a connecting chamber that includes the self-closing valve and a distal end of the gas supply pipe when the distance between the self-closing valve and the gas supply pipe is equal to or less than a threshold distance. A control device moves the gas tank backward to a position where the self-closing valve closes while the sealing of the connecting chamber is maintained. If the internal pressure of the gas supply pipe decreases, the control device outputs a gas leak signal indicating a gas leak that is not at a check valve. Otherwise, the control device moves the gas tank backward to a position where the connecting chamber is not sealed and, if the internal pressure of the gas supply pipe decreases, outputs a check valve abnormality signal indicating a gas leak at the check valve.

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

[0001] The present invention relates to a gas supply system that supplies gas from a gas tank to a gas utilization device. 2. Description of the related prior art

[0002] Unexamined Japanese patent application No. 2020-174019 (JP 2020-174019 A) discloses a gas supply system equipped with a plurality of gas tanks that delivers gas from the gas tanks to a gas utilization device. The gas supply system according to JP 2020-174019 A includes a check valve in a gas supply pipe that directs gas from a gas tank to the gas utilization device. JP 2020-174019 A discloses a test method for verifying the proper functioning of the check valve. BRIEF SUMMARY OF THE INVENTION

[0003] It is conceivable that gas could escape at points other than the check valve. The present description provides a gas supply system capable of both checking the check valve and detecting gas leaks at points other than the check valve.

[0004] A gas supply system disclosed in this specification comprises a gas tank, a gas supply pipe, an actuator, a seal, a check valve, a first and a second pressure sensor, and a control device. The gas tank includes a self-closing valve that opens when a push rod is pushed in and closes when the push rod is pulled out. The gas supply pipe is connected to the gas tank. The push rod is provided at a distal end of the gas supply pipe, and the gas supply pipe carries 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 closes a connecting space that includes an opening of the self-closing valve and the distal end of the gas supply pipe when the distance between the self-closing valve and the push rod is less than a predetermined threshold distance.The check valve is located in the gas supply pipe and prevents the backflow of gas. The first pressure sensor measures the pressure in the gas supply pipe upstream of the check valve. The second pressure sensor measures the pressure in the gas supply pipe downstream of the check valve.

[0005] When replacing a gas tank in a state where a gas supply pipe is connected and an automatic shut-off valve is open, the control device performs the following operations. (1) The control device reverses the gas tank to a position where the self-closing valve is closed while maintaining the seal of the connection space. (2) The control device reduces a predetermined amount of gas from the gas supply pipe on the downstream side of the check valve. Note that the control device may reduce the amount of gas in the gas supply pipe by activating a gas utilization device, or by diverting the gas to a sub-tank for temporary gas storage or the like. If the gas poses no environmental impact, the control device may also release a predetermined amount of gas into the atmosphere.(3) If the decrease in a reading from the first or second pressure sensor exceeds a predetermined first differential pressure threshold before and after the elapse of a first threshold time, the control device outputs a gas leak signal indicating that a gas leak is occurring at a location other than the check valve. The processing of (3) checks whether a gas leak is occurring at a location other than the check valve. (4) If the reading from the first or second pressure sensor does not exceed the first differential pressure threshold before and after the elapse of the first time period, the control device moves the gas tank backward to a position in which the seal of the connection chamber is separated.(5) If the reduction in the reading of the second pressure sensor exceeds a second differential pressure threshold before and after a second time interval, the control device outputs a check valve abnormality signal indicating that a gas leak is occurring at the check valve and also moves the gas tank forward to a position where the connection space is sealed. The processing of (5) checks whether a gas leak is occurring at the check valve. A gas supply system disclosed in this specification is capable of checking both a check valve and gas leaks at locations other than the check valve.

[0006] Details of the technology disclosed in this description and further improvements are described in the “DETAILED DESCRIPTION OF EXECUTION EXAMPLES” below. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Features, advantages, and technical and industrial significance of embodiments of the invention are described below with reference to the accompanying drawings, in which the same symbols denote the same elements and in which: Fig. 1 is a block diagram of a gas supply system according to an exemplary embodiment; Fig. Figure 2 is a cross-sectional view of a gas tank and a gas supply pipe (sealing position); Fig. Figure 3 is a cross-sectional view of the gas tank and gas supply pipe (valve opening position); Fig. 4 is a flowchart of the gas leakage testing process; and Fig. 5 is a flowchart of the gas leakage testing process (continued from Fig. 4). DETAILED DESCRIPTION OF THE EXECUTION EXAMPLES

[0008] A gas supply system 2 according to an exemplary embodiment is described with reference to the drawings. Fig. Figure 1 is a block diagram of the gas supply system 2. According to the exemplary embodiment, a fuel cell 90 is connected to the gas supply system 2, and the gas supply system 2 supplies the fuel cell 90 with hydrogen gas from a gas tank 10. The fuel cell 90 is an example of a gas utilization device to which the gas supply system 2 delivers gas.

[0009] The gas supply system 2 comprises the 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 control device 50 and a display device 51.

[0010] Gas tank 10 is filled with hydrogen gas under high pressure. Gas tank 10 and fuel cell 90 are connected by gas supply pipe 30. Gas supply pipe 30 carries the hydrogen gas from gas tank 10 to fuel cell 90. A check valve 31 and a pressure reducing valve 32 are connected to gas supply pipe 30. The pressure reducing valve 32 is located downstream of the check valve 31. The term "downstream" refers to the side of gas supply pipe 30 that is closer to fuel cell 90 (gas utilization device), and the term "upstream" refers to the side that is closer to gas tank 10.

[0011] The pressure reducing valve 32 reduces the pressure of the hydrogen gas supplied from the gas tank 10 to a pressure suitable for operating the fuel cell 90. That is, the gas pressure suitable for operating the fuel cell 90 is lower than the pressure of the gas supplied from the gas tank 10.

[0012] The check valve 31 allows gas to flow from upstream to downstream and prevents gas from flowing from upstream to downstream. The check valve 31 prevents hydrogen gas from escaping to the outside downstream of the check valve 31 if a gas leak occurs at a connection point between the gas tank 10 and the gas supply pipe 30.

[0013] The first pressure sensor 41 measures the pressure in the gas supply pipe 30 upstream of the check valve 31. When the gas tank 10 is connected to the gas supply pipe 30, a reading from the first pressure sensor 41 corresponds approximately to the internal pressure of the gas tank 10 (the reading from the first pressure sensor 41 will be lower than the internal pressure of the tank by the pressure loss due to a self-closing valve 20, etc., which will be described later).

[0014] The second pressure sensor 42 measures the pressure in the gas supply pipe 30 downstream of the check valve 31. As gas is supplied from the gas tank 10, a reading of the second pressure sensor 42 is essentially equal to the reading of the first pressure sensor 41 (the reading of the second pressure sensor 42 will be lower than the reading of the first pressure sensor 41 by an amount corresponding to a pressure loss due to the check valve 31, etc.).

[0015] A cross-sectional view of a neck 11 of the gas tank 10 and a distal end of the gas supply pipe 30 is shown on the lower side of Fig. Figure 1 shows the neck 11 of the gas tank 10 containing the self-closing valve 20. The self-closing valve 20 consists of a sleeve 21, a valve body 22, and a spring 23. The sleeve 21 is attached to an inner surface of the neck 11. The valve body 22 is located next to the sleeve 21 inside the tank. The spring 23 pushes the valve body 22 from the inside of the tank against an opening in the sleeve 21 (the opening that leads into the tank). One end of the spring 23 on the other side rests against an inner wall of the tank.

[0016] The valve body 22 is in close contact with the opening of the sleeve 21 under the force of the spring 23. The self-closing valve 20 is closed while the valve body 22 is in close contact with the opening of the sleeve 21. The self-closing valve 20 opens when the valve body 22 is pushed from the outside of the tank to the inside. When a load is removed from the valve body 22, the force of the spring 23 causes the valve body 22 to come back into close contact with the opening of the sleeve 21, thereby closing the self-closing valve 20.

[0017] The push rod 35 is located at the distal end of the gas supply pipe 30. The push rod 35 is secured at the distal end of the gas supply pipe 30 by a rod holder 36. The rod holder 36 has holes through which gas can flow from the gas tank 10 into the gas supply pipe 30.

[0018] When the gas tank 10 is inserted into the gas supply system 2, the push rod 35 at the distal end of the gas supply pipe 30 points towards the neck 11. The actuator 19 moves the gas tank 10 closer to and away from the gas supply pipe 30. More precisely, the actuator 19 moves the self-closing valve 20 closer to and away from the distal end of the gas supply pipe 30 (i.e., the push rod 35). The cross-sectional view in Fig. Figure 1 shows a state in which the push rod 35 is away from the self-closing valve 20.

[0019] The actuator 19 moves the gas tank 10 forwards and backwards relative to the distal end of the gas supply pipe 30. For simplicity, the approach of the gas tank 10 to the gas supply pipe 30 is referred to as "forward movement" and the departure of the gas tank 10 from the gas supply pipe 30 as "backward movement". The actuator can move the gas supply pipe 30 forwards and backwards relative to the gas tank 10.

[0020] Inside the neck 11 is a seal 12. As the distal end (pushrod 35) of the gas supply tube 30 approaches the self-closing valve 20, an outer circumference of the gas supply tube 30 comes into contact with the seal 12, and a space encompassing an opening of the self-closing valve 20 (the opening facing the outside of the gas tank 10) and the distal end of the gas supply tube 30 is sealed. For simplicity, the space encompassing the opening of the self-closing valve 20 and the distal end of the gas supply tube 30 is referred to as the "connection space S". More precisely, the connection space S refers to the space located inside the neck 11, including the opening of the self-closing valve 20 and the distal end of the gas supply tube 30. In the cross-sectional view in Fig. 1. The push rod 35 is removed from the self-closing valve 20, and a gap G is maintained between the distal end of the gas supply pipe 30 and the seal 12. In this state, the connection space S is not sealed against the external environment.

[0021] Fig. Figure 2 shows a cross-section where the distal end of the gas supply tube 30 is in contact with the seal 12. When the distance between the push rod 35 and the self-closing valve 20 reaches L1, the seal 12 comes into contact with the outer circumference of the gas supply tube 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 self-closing valve 20 becomes less than L1, the connection space S is sealed off from the external environment. When the distance between the push rod 35 and the valve body 22 is L1, the self-closing valve 20 remains closed. The distance L1 can be referred to as the threshold distance.

[0022] The hidden outlines in Fig. Figure 2 indicates a state in which the gas tank 10 has moved forward until the valve body 22 comes into contact with the distal end of the push rod 35. If the gas tank 10 moves further forward than the obscured outlines, the push rod 35 forces open the self-closing valve 20. Fig. Figure 3 is a cross-sectional view showing the gas tank 10 moving forward until the self-closing valve 20 opens. The thick arrows A indicate the gas flow. While the self-closing valve 20 is open, the hydrogen gas in the gas tank 10 flows through the connecting chamber S to the gas supply pipe 30. The connecting chamber S is sealed by the gasket 12, preventing the hydrogen gas from escaping.

[0023] The gas in the gas tank 10 flows through the self-closing valve 20, which is open, through the holes in the rod support 36 and flows to the gas supply pipe 30. For the sake of simplicity, the position of the gas tank 10 in which the connecting space S is sealed, but the self-closing valve 20 is closed, is referred to as the "sealing position" and the position of the gas tank 10 in which the connecting space S is sealed and the self-closing valve 20 is open is referred to as the "valve opening position". Fig. Figure 2 is a cross-sectional view in the sealing position, and Fig. Figure 3 shows a cross-sectional view in the valve open position. The sealing position is a situation in which the distance between the push rod 35 and the valve body 22 of the self-closing valve 20 is equal to or less than L1 and also greater than zero. Furthermore, in the valve open position, the seal 12 rests against the outer circumference of the gas supply pipe 30, and the connecting space S remains closed.

[0024] As in Fig. As shown in Figure 1, the position of the gas tank 10 in which the seal of the connecting space S is separated and the connecting space S is in contact with the external environment is referred to as the separation position.

[0025] When a new gas tank 10 is placed on the actuator 19, the control unit 50 moves (see Fig. 1) Move the gas tank 10 forward into the open position. The self-closing valve 20 opens, and the gas in 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 is put into operation. The control unit 50 controls the fuel cell 90.

[0026] When the remaining quantity in gas tank 10 is running low, the gas tank 10 must be replaced. If a malfunction of the check valve 31 occurs during the removal of the old gas tank 10, hydrogen gas can escape. Accordingly, the control unit 50 performs a gas leakage test before the gas tank 10 is moved backward into the disconnect position. That is, the control unit 50 performs the gas leakage test when the gas tank 10 is replaced, to which the gas supply pipe 30 is connected and the self-closing valve 20 is open.

[0027] Fig. 4 and Fig. Figure 5 shows the flowcharts of the gas leakage testing procedure performed by the control unit 50. First, the control unit 50 controls the actuator 19 to move the gas tank 10 into the sealing position (step S12). In the sealing position, the self-closing valve 20 is closed, but the connection space S is maintained in a sealed state.

[0028] Next, the control device 50 reduces a predetermined amount of gas in the gas supply pipe 30 downstream of the check valve 31 (step S13). The control device 50 can reduce the gas in the gas supply pipe 30 by operating the fuel cell 90, or it can reduce the gas in the gas supply pipe 30 by diverting some of the gas in the gas supply pipe 30 to a reserve tank, which is not shown in the figure. The control device 50 can also allow a predetermined amount of gas in the gas supply pipe 30 to be released into the atmosphere, as long as the gas does not adversely affect the environment.

[0029] When the gas flow in the gas supply pipe 30 is reduced on the downstream side of the check valve 31, the pressure in the gas supply pipe 30 on the downstream side of the check valve 31 becomes lower than the pressure on the upstream side of the check valve 31. The gas on the upstream side of the check valve 31 flows through the check valve 31 to the downstream side, and the pressure on the upstream side and the pressure on the downstream side of the check valve 31 equalize. That is, the readings of the first pressure sensor 41 and the second pressure sensor 42 become the same.

[0030] The control device 50 then remains in standby mode for a predetermined initial time period (step S14). During this time, the control device 50 stores the measured values ​​of the pressure sensors 41 and 42 before and after the elapsed time period (step S14). For simplicity, 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) is 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) is referred to as the second measured value.

[0031] After the first time interval has elapsed, the control unit 50 checks whether the decrease in the first measured value before and after the first time interval, or the decrease in the second measured value before and after the first time interval, 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 time interval exceeds the first differential pressure threshold (YES in step S15), this indicates that gas is escaping from the gas supply pipe 30 to the outside. At this point, the control unit 50 outputs a signal (gas leak signal) to the indicator unit 51, indicating that a gas leak is occurring at a location other than the check valve 31, and shuts down the gas supply system 2 and the fuel cell 90 (YES in step S15, steps S16 and S17).Upon receiving the gas leakage signal, the indicator device 51 switches on a warning lamp (or the indicator device 51 emits a warning tone) indicating that a gas leak from the gas supply pipe 30 is occurring at a location other than the check valve 31.

[0032] If the reduction in the first or second reading before and after the first time interval does not exceed the first differential pressure threshold (NO in step S15), it is determined that no gas leak is occurring except at check valve 31. Note that at this point it is unclear whether an abnormality has occurred at check valve 31.

[0033] If the determination in step S15 is “NO”, the control device 50 moves the gas tank 10 into the disconnect position (step S21). In the disconnect position, the connecting chamber S is no longer sealed and is connected to the external environment. At this point, the first measured value is equal to atmospheric pressure.

[0034] The control unit 50 then remains ready for a predetermined second time period (step S22). At this time, the control unit 50 stores the second measured value (measured value of the second pressure sensor 42) before and after the second time period has elapsed (step S22).

[0035] After the second time interval has elapsed, the control unit 50 checks whether the decrease in the second measured value before and after the second time interval exceeds a predetermined threshold (second differential pressure threshold) (step S23). If the decrease in the second measured value before and after the second time interval exceeds the second differential pressure threshold (YES in step S23), this means that gas is flowing from the downstream side to the upstream side of the check valve 31 and gas is escaping from the connecting chamber S into the external environment. In other words, this means that an abnormality has occurred at the check valve 31. At this point, the control unit 50 outputs a signal (check valve abnormality signal) to the indicator unit 51, indicating that a gas leak is occurring at the check valve 31 (step S25).Upon receiving the check valve abnormality signal, the indicator device 51 displays a message (or emits a warning tone) indicating that an abnormality has occurred in the check valve 31.

[0036] Furthermore, the control unit 50 moves the gas tank 10 into the sealing position (step S26). By moving the gas tank 10 into the sealing position, the connection chamber S is sealed. Therefore, gas leakage is stopped even in the event of an abnormality in the check valve 31. Finally, the control unit 50 shuts down the system (step S27).

[0037] If the branch determination in step S15 is "NO", it is finally determined that no further gas leak occurs except at check valve 31. If the reduction amount of the second measured value exceeds the second differential pressure threshold in step S23, a defect in check valve 31 is accordingly determined to be the cause.

[0038] If the reduction amount of the second measured value is lower than the second differential pressure threshold value in step S23, the check valve 31 is also determined to be normal. In this case, the control unit 50 outputs a signal (normal signal) to the display unit 51, indicating that there is no gas leak, including from the check valve 31 (NO in steps S23 and S24). The display unit 51, receiving the normal signal, displays a message stating that there is no gas leak in the gas supply system 2 and that the gas tank 10 can be replaced. When an operator sees the message that the gas tank 10 can be replaced, the operator replaces the gas tank 10, which is in the disconnect position, with a new gas tank.

[0039] The gas supply system 2 according to the embodiment can check both the check valve 31 and gas leaks outside the check valve.

[0040] The following section describes the technology outlined in the exemplary embodiment. The gas leakage testing procedure performed by the control unit 50 of the gas supply system 2 is as follows. When replacing the gas tank 10, to which the gas supply pipe 30 is connected and the self-closing valve 20 is open, the control unit 50 performs the following operations. (1) The control unit 50 moves the gas tank 10 backward to a position in which the self-closing valve is closed (sealing position), maintaining the seal of the connection chamber S (step S12). (2) The control unit 50 reduces a predetermined amount of gas from the gas supply pipe 30 downstream of the check valve 31 (step S13). Subsequently, the control unit 50 remains in standby mode for an initial period of time (step S14).At this point, the control unit stores the first and second measured values ​​before and after the first time interval has elapsed (step S14). (3) If the decrease in the measured value of the first pressure sensor 41 or the second pressure sensor 42 before and after the first time interval exceeds the predetermined first differential pressure threshold, the control unit 50 outputs a gas leak signal indicating that a gas leak is occurring outside the check valve (YES in steps S15 and S16). The processing of (3) checks whether a gas leak is occurring at a location other than the check valve.

[0041] (4) If the reduction in the measured value of the first pressure sensor or the second pressure sensor before and after the first time interval does not exceed the first differential pressure threshold, the control device 50 moves the gas tank 10 backward to a position (separation position) in which the seal of the connecting chamber S is separated (NO in step S15 and step S21). The control device 50 then waits for the second time interval (step S22). At this point, the control device 50 stores the second measured value before and after the second time interval (step S22).(5) If the decrease in the reading of the second pressure sensor 42 before and after the second time interval exceeds the second differential pressure threshold, the control device 50 outputs a check valve abnormality signal indicating that a gas leak is occurring at the check valve 31 and moves the gas tank 10 forward to a position where the connection chamber S is sealed (sealing position) (YES in step S23, steps S25, S26). The processing of (5) checks whether a gas leak is occurring at the check valve 31. The gas supply system 2 according to the exemplary embodiment can check both the check valve 31 and gas leaks at locations other than the check valve.

[0042] Note that the first and second time periods can range from a few tens of seconds to several minutes. These periods are defined as times during which a significant pressure drop in gas supply pipe 30 is expected if a gas leak occurs.

[0043] Although specific examples of the present invention have been described in detail above, these examples are merely examples and do not limit the scope of the claims. The technology described in the claims comprises various modifications and variations of the specific examples described above. The technical elements described in this specification or in the drawings have technical benefits, either individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology illustrated by way of example in this description or in the drawings can fulfill a multitude of purposes simultaneously, and the achievement of any one of these purposes itself has technical benefits. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2020-174019 A

[0002] JP 2020

[0002] JP 174019 A

[0002]

Claims

A gas supply system comprising: a gas tank having a self-closing valve that opens when a push rod is inserted and closes when the push rod is withdrawn; a gas supply pipe to which the gas tank is connected, the distal end of which has the push rod and directs the gas from the gas tank to a gas utilization device; an actuator that moves the gas tank forwards and backwards relative to the gas supply pipe; a seal that seals a connecting space comprising an opening of the self-closing valve and the distal end of the gas supply pipe when the distance between the self-closing valve and the push rod is less than a predetermined threshold distance; a check valve provided in the gas supply pipe that prevents backflow of gas; a first pressure sensor that measures a pressure in the gas supply pipe upstream of the check valve; a second pressure sensor,which measures a pressure in the gas supply pipe downstream of the check valve; and a control device, wherein the control device, when exchanging the gas tank in a state where the gas supply pipe is connected and the self-closing valve is open, moves the gas tank backward to a position where the self-closing valve is closed while maintaining the seal of the connection space, reduces a predetermined amount of gas from the gas supply pipe on a downstream side of the check valve, outputs a gas leakage signal indicating that a gas leak is occurring elsewhere than at the check valve when a reduction amount in a reading from the first pressure sensor or the second pressure sensor, before and after a first time amount elapses, exceeds a predetermined first differential pressure threshold, and moves the gas tank backward to a positionin which the sealing of the connection chamber is broken when the reduction in the reading of the first pressure sensor or the second pressure sensor, before and after the first time interval, does not exceed the first differential pressure threshold, and a check valve abnormality signal is output indicating that a gas leak is occurring at the check valve, and furthermore, the gas tank is moved forward to a position in which the connection chamber is sealed when the reduction in the reading of the second pressure sensor, before and after a second time interval, exceeds a predetermined second differential pressure threshold.

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