Safety device for high-pressure gas tank

Abstract

A safety device (10) for a high-pressure gas tank (3) that internally accommodates a high-pressure gas as a fuel for a vehicle (2) comprises a safety valve (1) that is attached to the high-pressure gas tank (3), and a heat pipe (5) that is attached to the safety valve (1). The safety valve (1) discharges the high-pressure gas from the inside of the high-pressure gas tank (3) to the outside as the temperature rises. The heat pipe (5) causes the heat to move due to evaporation and condensation of a working liquid sealed inside the heat pipe (5) and the capillary action of wicks provided to the inner wall of the heat pipe (5).

Description

High-pressure gas tank safety devices

[0001] This case relates to a safety device for a high-pressure gas tank that contains high-pressure gas as a fuel for a vehicle.

[0002] Conventionally, there are vehicles that run on high-pressure gas as fuel. For example, fuel cell vehicles are known that run on electricity generated by a chemical reaction between high-pressure hydrogen gas and oxygen (air). Vehicles that run on high-pressure gas as fuel are equipped with a high-pressure gas tank that stores the high-pressure gas inside.

[0003] Generally, high-pressure gas tanks installed in vehicles are equipped with a safety valve that releases high-pressure gas from the inside of the high-pressure gas tank to the outside as the temperature rises. For example, Patent Document 1 discloses an example of such a safety valve, a thermally activated overpressure prevention device that operates to release a portion of the hydrogen (high-pressure gas) compressed and filled in the hydrogen tank (high-pressure gas tank) into the atmosphere in a short period of time when the internal temperature of the hydrogen tank (high-pressure gas tank) reaches or exceeds a predetermined temperature.

[0004] JP 2022-88966 A

[0005] However, because the above-mentioned safety valves are activated (opened) by heat, there is a risk that they may activate late or not at all when the temperature rises at a location distant from the safety valve. In particular, in commercial vehicles such as trucks and buses, the high-pressure gas tanks are large, so even if a fire occurs near the high-pressure gas tank, the location of the fire may be far from the installation position of the safety valve, making it difficult to properly activate the safety valve.

[0006] To address this issue, it is conceivable to install safety valves in three or more locations, including both ends and the middle of the high-pressure gas tank, so that the tank can respond to temperature increases at each of these locations. However, in this case, the manufacturing costs increase as the number of safety valves increases. Furthermore, in a vehicle in which multiple high-pressure gas tanks are installed at distances from each other, even if a temperature increase occurs near one high-pressure gas tank, it is desirable to activate the safety valves of the other high-pressure gas tanks as well to release high-pressure gas to the outside in order to prevent secondary damage.

[0007] The present invention was devised in view of the above-mentioned problems, and one of its objectives is to more appropriately operate the safety valve in a safety device for a high-pressure gas tank.

[0008] The present invention has been made to solve at least part of the above problems, and can be realized as the following aspects or application examples.

[0009] (1) The safety device for a high-pressure gas tank according to this embodiment is a safety device for a high-pressure gas tank that stores high-pressure gas as a vehicle fuel inside, and includes a safety valve attached to the high-pressure gas tank that releases the high-pressure gas from the inside to the outside of the high-pressure gas tank as the temperature rises, and a heat pipe connected to the safety valve that transfers heat by evaporation and condensation of a working fluid sealed inside and by capillary action of a wick provided on the inner wall.

[0010] According to this aspect, a heat pipe is connected to a safety valve that releases high-pressure gas from the inside of a high-pressure gas tank to the outside as the temperature rises. Therefore, heat can be transferred to the safety valve through the heat pipe, which has a higher thermal conductivity than stainless steel, copper, aluminum, etc. As a result, even in the event of an ignition at a location far from the safety valve, heat is transferred quickly and efficiently through the heat pipe from the ignition location to the safety valve, allowing the safety valve to operate as the temperature rises and appropriately release the high-pressure gas. Therefore, this aspect allows the safety valve to operate more appropriately. That is, because the heat pipe, which has excellent thermal conductivity, is extended, the temperature rise can be transmitted to the safety valve by increasing heat sensitivity over a wide area without increasing the number of safety valves. This minimizes the need for an increase in the number of safety valves, thereby reducing costs. Furthermore, because the heat pipe is a heat transfer device for transferring heat to the safety valve and high-pressure gas does not flow through it, even if the heat pipe is deformed or damaged, high-pressure gas does not leak. Therefore, leakage of high-pressure gas can be suppressed even when an impact is applied, for example, during a vehicle collision.

[0011] (2) In the safety device for a high-pressure gas tank according to this aspect, the high-pressure gas tank may have a cylindrical middle portion and a pair of hemispherical end portions formed on either side of the middle portion. The safety valve may be attached to at least one of the end portions, and the heat pipe may include a main pipe extending from the safety valve attached to the end portion along the middle portion. With this configuration, heat can be transferred to the safety valve through the main pipe even when the temperature rises in the middle portion of the high-pressure gas tank. Therefore, for example, when a safety valve is attached to at least one of the ends of the high-pressure gas tank, the safety valve can be appropriately activated even when the temperature rises near the middle portion of the high-pressure gas tank. In other words, even without providing an additional safety valve in the middle portion of the high-pressure gas tank, the main pipe can activate the safety valve attached to at least one of the ends of the high-pressure gas tank when the temperature rises near the middle portion of the high-pressure gas tank. Therefore, high-pressure gas can be appropriately released from the high-pressure gas tank when the temperature rises while suppressing cost increases.

[0012] (3) In the high-pressure gas tank safety device according to this aspect, the high-pressure gas tank may be mounted on the vehicle with the center of the intermediate portion extending horizontally, and the main pipe may extend downward from the safety valve attached to the end and then extend along the intermediate portion. This configuration allows the main pipe to extend along the intermediate portion of the high-pressure gas tank at a position lower than the safety valve. This main pipe allows the working fluid (gas) evaporated by heat near the intermediate portion of the high-pressure gas tank to move upward due to the characteristics of a heat pipe, thereby transferring heat to the safety valve. In other words, since the direction of heat transfer through the main pipe to the safety valve is upward, heat can be transferred more quickly and efficiently through the main pipe to the safety valve. Therefore, the safety valve can be more appropriately operated when the temperature rises near the intermediate portion of a horizontally placed high-pressure gas tank whose center extends horizontally.

[0013] (4) In the high-pressure gas tank safety device according to this aspect, the high-pressure gas tank may be mounted on the vehicle with the center of the intermediate portion extending vertically, the safety valve may be attached to the upper end portion, and the main pipe may extend diagonally downward from the safety valve attached to the end portion and then extend along the intermediate portion. With this configuration, the main pipe can be extended along the intermediate portion of the high-pressure gas tank at a position lower than the safety valve. With this main pipe, heat is transferred upward to the safety valve as described above, allowing heat to be transferred more quickly and efficiently through the main pipe to the safety valve. Therefore, the safety valve can be more appropriately operated when the temperature rises near the intermediate portion of a vertically-mounted high-pressure gas tank with the center of the intermediate portion extending vertically.

[0014] (5) In the high-pressure gas tank safety device according to this aspect, the high-pressure gas tank may be installed rearward of the vehicle cab and outward of a chassis frame in the vehicle width direction, and the heat pipe may be provided in the space between the chassis frame and the high-pressure gas tank. With this configuration, the high-pressure gas tank can protect the heat pipe from an impact applied from the outside in the vehicle width direction during a side collision, for example. This reduces the risk of damage to the heat pipe during a side collision.

[0015] (6) In the high-pressure gas tank safety device according to this aspect, the high-pressure gas tank may be installed between a cab and a rear body of the vehicle, and the heat pipe may be provided in the space between the rear body and the high-pressure gas tank. With this configuration, the high-pressure gas tank can protect the heat pipe from an impact input from the front during a frontal collision, for example. This reduces the risk of damage to the heat pipe during a frontal collision of the vehicle.

[0016] (7) The high-pressure gas tank safety device according to this aspect may include a safety valve attached to each of the multiple high-pressure gas tanks, and the heat pipe may include a common pipe thermally connected to each of the safety valves. With this configuration, heat can be transferred to each of the safety valves attached to the multiple high-pressure gas tanks through the common pipe. This allows heat to be transferred from the ignition location to each safety valve through the common pipe, even in the event of a fire at a location far from some of the safety valves. As a result, each safety valve operates in response to a temperature rise, allowing the high-pressure gas to be appropriately released from the inside to the outside of each high-pressure gas tank. Therefore, in a vehicle equipped with multiple high-pressure gas tanks, if a temperature rise occurs near one high-pressure gas tank, not only the safety valve attached to that high-pressure gas tank but also the safety valves attached to the other high-pressure gas tanks can be more appropriately activated. This effectively prevents secondary damage.

[0017] (8) In the high-pressure gas tank safety device according to this aspect, the common pipe may extend along a gas supply pipe connected to a plurality of the high-pressure gas tanks to deliver the high-pressure gas to a predetermined destination. With this configuration, when the temperature near the gas supply pipe rises, heat can be transferred through the common pipe to each of the plurality of safety valves. As a result, in the event of a fire near the gas supply pipe, for example, each safety valve operates in response to the temperature rise, allowing the high-pressure gas to be appropriately released from the inside to the outside of each high-pressure gas tank. Furthermore, the common pipe can be easily installed by laying it along an existing gas supply pipe.

[0018] (9) In the high-pressure gas tank safety device according to this aspect, the common pipe may extend along the vehicle height direction and be thermally connected to each of the safety valves attached to the plurality of high-pressure gas tanks arranged in the vehicle height direction. This configuration allows the common pipe to be appropriately applied to high-pressure gas tanks arranged in the vehicle height direction. Therefore, when the temperature rises at any position in the vehicle height direction, heat can be transferred to each safety valve through the common pipe. This allows each safety valve of the high-pressure gas tanks arranged in the vehicle height direction to be more appropriately operated.

[0019] (10) In the high-pressure gas tank safety device according to this aspect, the common pipe may extend along the vehicle width direction and be thermally conductively connected to each of the safety valves attached to the plurality of high-pressure gas tanks arranged in the vehicle width direction. This configuration allows the common pipe to be appropriately applied to the high-pressure gas tanks arranged in the vehicle width direction. Therefore, when the temperature rises at any position in the vehicle width direction, heat can be transferred to each safety valve through the common pipe. This allows each safety valve of the high-pressure gas tanks arranged in the vehicle width direction to be more appropriately operated.

[0020] (11) In the safety device for a high-pressure gas tank according to this aspect, the safety valve may include a sensing unit that opens a discharge port for discharging the high-pressure gas to the outside in response to a temperature rise; a housing that accommodates the sensing unit; and a first connection unit that is a hole or groove formed in the housing adjacent to the sensing unit, and the heat pipe may be connected to the first connection unit. This configuration facilitates heat transfer from the heat pipe to the sensing unit, thereby enabling more appropriate operation of the safety valve. In other words, directly connecting the heat pipe to the housing of the safety valve allows for efficient heat transfer from the heat pipe through the housing to the sensing unit within the housing. Furthermore, because the heat pipe can be connected simply by forming a hole or groove in an existing housing, manufacturing costs can be reduced and the number of heat pipes can be flexibly increased or decreased.

[0021] (12) In the safety device for a high-pressure gas tank according to this aspect, the safety valve may include a sensing unit that opens a discharge port for discharging the high-pressure gas to the outside in response to a temperature rise, and a housing that accommodates the sensing unit. The safety device may further include a collar made of a material with a higher thermal conductivity than the housing, attached to the housing, and having a second connection unit that is a hole or groove formed adjacent to the sensing unit. The heat pipe may be connected to the second connection unit. This configuration facilitates heat transfer from the heat pipe to the sensing unit, thereby enabling more appropriate operation of the safety valve. In other words, connecting the heat pipe to the housing via a collar that has a higher thermal conductivity than the safety valve housing allows for efficient heat transfer from the heat pipe to the sensing unit via the collar and housing. Furthermore, since the heat pipe can be connected simply by attaching a collar to an existing housing, the existing housing can be used as is, and the use of a collar, which is an add-on part, allows for flexible adjustments to the number of heat pipes.

[0022] (13) The safety device for a high-pressure gas tank according to this aspect may further include a protective member formed in a plate or lattice shape with numerous holes and covering the heat pipe. This configuration allows the heat pipe to be protected by the protective member while still allowing heat from the surroundings to be transferred to the heat pipe. Therefore, even if an impact is applied during a vehicle collision, deformation or damage to the heat pipe can be suppressed. This allows the safety valve to operate more appropriately.

[0023] (14) In the safety device for a high-pressure gas tank according to this aspect, the vehicle may be a fuel cell vehicle that drives a driving motor using power from a fuel cell, and the high-pressure gas tank may be a hydrogen tank that stores hydrogen gas as the high-pressure gas. With this configuration, the safety valve operates more appropriately as described above, allowing hydrogen gas to be appropriately released from the inside of the high-pressure gas tank to the outside. This allows for appropriate response to temperature increases in the fuel cell vehicle.

[0024] According to the present invention, the safety valve in the safety device for the high-pressure gas tank can be operated more appropriately.

[0025] 1 is a schematic top view of a vehicle to which a safety device for a high-pressure gas tank according to one embodiment is applied; FIG. 1 is a cross-sectional view showing an example of a safety valve provided in the safety device of FIG. 1; FIG. 1 is a cross-sectional view showing a schematic peripheral structure of the high-pressure gas tank of FIG. 1; FIG. 2 is a perspective view showing an example of a connection structure between a safety valve and a heat pipe provided in the safety device of FIG. 1; FIG. 3 is a perspective view showing another example of the connection structure of FIG. 4; FIG. 5 is a perspective view showing a modified collar in the connection structure of FIG. 5; FIG. 6 is a top view showing an example of a connection structure between heat pipes provided in the safety device of FIG. 1; FIG. 7 is a left side view of a main part of a vehicle to which a safety device according to a first modified example is applied; FIG. 8 is a schematic perspective view of a main part of the vehicle of FIG. 8, viewed from a diagonal rear right; FIG. 9 is a schematic perspective view (corresponding to FIG. 9) of a main part of a vehicle to which a safety device according to a second modified example is applied, viewed from a diagonal rear right; FIG. 10 is a schematic perspective view (corresponding to FIG. 9) of a main part of a vehicle to which a safety device according to a third modified example is applied, viewed from a diagonal rear right.

[0026] The following describes embodiments (aspects, application examples) of the present invention with reference to the drawings. The following embodiments are merely examples, and are not intended to exclude various modifications or applications of techniques not explicitly described in the embodiments. The configurations of the following embodiments can be modified in various ways without departing from the spirit of the invention. Furthermore, they can be selected or combined as needed.

[0027] 1, a high-pressure gas tank safety device 10 (hereinafter simply referred to as the safety device 10) according to this embodiment is applied to a high-pressure gas tank 3 (hereinafter simply referred to as the tank 3) mounted on a vehicle 2. The vehicle 2 is, for example, a fuel cell vehicle that drives a driving motor 24 with power from a fuel cell 23. More specifically, the vehicle 2 is equipped with a high-voltage battery 25 that stores power from the fuel cell 23, and drives the motor 24 with the power stored in the high-voltage battery 25.

[0028] Here, a vehicle 2 is illustrated that includes a cab 21 in which a driver's seat (not shown) is provided, a rear body 29 provided behind the cab 21, and a chassis frame 22 that supports the cab 21 and the rear body 29 from below. In Fig. 1, both the cab 21 and the rear body 29 are indicated by two-dot chain lines.

[0029] The chassis frame 22 of this embodiment has a ladder frame structure. Specifically, the chassis frame 22 has a pair of side rails 26 extending in the vehicle length direction D1 (front-rear direction) and multiple cross members 27 (only two are shown in FIG. 1 ) extending in the vehicle width direction D2 (left-right direction), forming a ladder shape. The pair of side rails 26 are spaced apart from each other in the vehicle width direction D2, and each cross member 27 connects the pair of side rails 26 to each other. The rear body 29 is, for example, a cargo box. In this way, the vehicle 2 may be a truck (fuel cell truck) equipped with the rear body 29 that is a cargo box.

[0030] The fuel cell 23 is a device that generates electricity through a chemical reaction between hydrogen and oxygen (air). The fuel cell 23 is disposed, for example, below the cab 21, between a pair of side rails 26. Hydrogen gas is supplied to the fuel cell 23 from the tank 3 through a gas supply pipe 28 and a downstream pipe 31, which will be described later. In other words, the fuel cell 23 is a predetermined supply destination for the hydrogen gas supplied from the tank 3.

[0031] The high-voltage battery 25 is disposed, for example, between a pair of side rails 26, rearward of the cab 21 and the fuel cell 23. The motor 24 is disposed, for example, between the pair of side rails 26, rearward of the high-voltage battery 25. The motor 24 is modularized with an inverter (not shown).

[0032] The tank 3 is a sealed container that stores high-pressure gas as fuel for the vehicle 2. The tank 3 mounted on the vehicle 2, which is a fuel cell vehicle, is a hydrogen tank that stores hydrogen gas as high-pressure gas. In this embodiment, two (plural) tanks 3 (a first tank 3A and a second tank 3B) are illustrated as an example, each installed rearward of the cab 21 and outward of the chassis frame 22 in the vehicle width direction D2.

[0033] The first tank 3A is provided outward in the vehicle width direction D2 from one (the left side in FIG. 1 ) of a pair of side rails 26 that extend in the vehicle length direction D1 on the chassis frame 22 having a ladder frame structure. The second tank 3B is provided outward in the vehicle width direction D2 from the other (the right side in FIG. 1 ) side rail 26. In this manner, in this embodiment, the first tank 3A is disposed on the left side of the left side rail 26, and the second tank 3B is disposed on the right side of the right side rail 26.

[0034] Each tank 3 has, for example, a cylindrical middle portion 3c and a pair of hemispherical end portions 3f, 3r formed on both sides of the middle portion 3c. In this embodiment, the tank 3 is a horizontally mounted tank in which a center 3d (axis center, hereinafter also referred to as the tank center 3d) of the middle portion 3c extends horizontally. More specifically, the tank 3 is installed in such a position that the tank center 3d extends along the vehicle length direction D1, similar to the side rails 26. When distinguishing between the pair of end portions 3f, 3r located on both sides of the tank center 3d for a tank 3 disposed in such a position, the front one is also referred to as the front end portion 3f and the rear one is also referred to as the rear end portion 3r.

[0035] In this embodiment, the first tank 3A and the second tank 3B are illustrated as having the same shape and being installed in the same orientation. However, the shape and orientation of each tank 3 are not limited to the above example, and the first tank 3A and the second tank 3B may have different shapes and may be mounted on the vehicle 2 in different orientations.

[0036] Each tank 3 is disposed in a space between a front wheel 34 and a rear wheel 35 of the vehicle 2. From the viewpoint of safety, the tank 3 is disposed inward in the vehicle width direction D2 by a predetermined distance or more from an outer surface 37 of the vehicle 2 (for example, the outermost surface of the rear body 29). Therefore, a space of a predetermined distance or more is provided outward from the tank 3 in the vehicle width direction D2.

[0037] A gas supply pipe 28 for sending high-pressure gas to a predetermined destination is connected to the two tanks 3. In this embodiment, the gas supply pipe 28 is a pipe for sending hydrogen gas from each tank 3 to the fuel cell 23, extends along the vehicle width direction D2, and connects the front ends 3f of the two tanks 3 to each other. The gas supply pipe 28 is connected to the fuel cell 23 via a downstream pipe 31. Note that various devices (not shown), such as filters and valves, are provided on the downstream pipe 31.

[0038] The fan 9 and the heat exchanger 4 are installed outward in the vehicle width direction D2 from each tank 3. As described above, the fan 9 and the heat exchanger 4 are arranged in a space of at least a predetermined dimension that is provided outward in the vehicle width direction D2 from the tank 3. In other words, the fan 9 and the heat exchanger 4 are mounted by utilizing dead space that exists outward in the vehicle width direction D2 from the tank 3.

[0039] The heat exchanger 4 is a device that exchanges heat between air and a refrigerant that cools devices mounted on the vehicle 2. The fan 9 is a blower (a so-called radiator fan) that guides air to the heat exchanger 4. FIG. 1 shows an example in which the heat exchanger 4 is arranged outward of the fan 9 in the vehicle width direction D2. However, the arrangement of the fan 9 and the heat exchanger 4 is not limited to this. The fan 9 may be arranged in any position as long as it can guide air to the heat exchanger 4. For example, contrary to the example in FIG. 1, the fan 9 may be arranged outward of the heat exchanger 4 in the vehicle width direction D2. Also, while FIG. 1 shows an example in which multiple fans 9 are arranged along the vehicle length direction D1, the number and arrangement of the fans 9 are not limited to this.

[0040] A side cover 32 is attached outward in the vehicle width direction D2 from the fan 9 and the heat exchanger 4 to protect the fan 9 and the heat exchanger 4. The side cover 32 is provided with a slit (not shown) to efficiently take in the airflow from the vehicle while it is traveling toward the fan 9 and the heat exchanger 4 (inward in the vehicle width direction D2).

[0041] [1-2. Main Configuration] The safety device 10 according to this embodiment includes a safety valve 1 attached to the tank 3 and a heat pipe 5 connected to the safety valve 1. Here, an example is shown in which the safety valve 1 is attached to each end 3f, 3r of the tank 3 on the tank center 3d. As such, for a relatively large tank 3, it is preferable to attach multiple safety valves 1 to multiple locations on the tank 3 (each end 3f, 3r in this embodiment). However, it is sufficient that at least one safety valve 1 is attached to each tank 3, and for example, the safety valve 1 may be attached to only one of the ends 3f, 3r of each tank 3 (the front end 3f or the rear end 3r).

[0042] The safety valve 1 is a device that releases high-pressure gas from the inside of the tank 3 to the outside as the temperature rises, and is also called a TPRD (Thermal Pressure Relief Device). The safety valve 1 attached to the front end 3f of each tank 3 is provided as an OTV (On Tank Valve) that combines various functions, such as a temperature sensor, a pressure sensor, and a solenoid valve (not shown). In contrast, the safety valve 1 attached to the rear end 3r of each tank 3 is provided as a plug that only functions as a TPRD.

[0043] As shown in Fig. 2, the safety valve 1 of this embodiment has a glass cylinder 12 (sensing part) filled with liquid, and a housing 6 that houses the cylinder 12. The housing 6 has a main body 13 that forms a passage for high-pressure gas, and a cap 14 that is formed in a cylindrical shape with a bottom and that covers the cylinder 12 and is attached to the main body 13, and is made of, for example, stainless steel. In Fig. 2, the cross section (hatching) of the cylinder 12 is omitted.

[0044] The main body 13 of the housing 6 is formed with an inlet port 6a that communicates with the tank 3, an outlet port 6b that discharges high-pressure gas toward a predetermined destination, and a gas passage 6c that extends between the inlet port 6a and the outlet port 6b. The main body 13 also is formed with a discharge port 6d that discharges high-pressure gas from inside the tank 3 to the outside of the vehicle 2, and a discharge passage 6e that branches off from the gas passage 6c and extends to the discharge port 6d. In this embodiment, the gas supply pipe 28 shown in FIG. 1 is connected to the outlet port 6b. Furthermore, a discharge pipe (not shown) that discharges high-pressure gas to the outside of the vehicle 2 is connected to the discharge port 6d.

[0045] A plunger 11 capable of reciprocating in the discharge passage 6e is provided within the housing 6. The plunger 11 is disposed in the discharge passage 6e while being biased toward the cylinder 12 and the cap 14 by a spring 18 attached to its outer periphery. When the plunger 11 is biased toward the cap 14 via the cylinder 12 in this manner, it is fixed in a position that closes the discharge passage 6e. Therefore, in this state, the discharge port 6d is closed. The state in which the discharge port 6d is closed can be said to be a state in which the safety valve 1 is not activated (closed).

[0046] On the other hand, when the liquid in the cylinder 12 expands with a rise in temperature and the cylinder 12 cracks, the plunger 11 moves toward the cap 14 due to the biasing force of the spring 18. As a result, the plunger 11 moves to a position that opens the discharge passage 6e. This opens the discharge port 6d, allowing the high-pressure gas to be discharged from the inside of the tank 3 to the outside through the discharge passage 6e and the discharge port 6d.

[0047] In this way, the cylinder 12 has the function of moving the plunger 11 by deforming with an increase in temperature, thereby causing the plunger 11 to open the discharge passage 6e. That is, the cylinder 12 opens the discharge port 6d with an increase in temperature. The state in which the discharge port 6d is open can be said to be the state in which the safety valve 1 is activated (open). The cylinder 12 and the cap 14 that houses it are provided to protrude from the main body 13 so that the liquid in the cylinder 12 can effectively receive the ambient heat (increasing sensitivity to an increase in ambient temperature).

[0048] 1 and 3, the heat pipe 5 is a tubular heat transfer device. The heat pipe 5 transfers heat by evaporation and condensation of a working fluid sealed inside and by capillary action of a wick provided on the inner wall. More specifically, the heat pipe 5 is made of a material with relatively high thermal conductivity (copper, aluminum, etc.), and a liquid called a working fluid (pure water, alcohol, etc.) is sealed in the hollow part of the pipe. A capillary structure called a wick is formed on the inner wall of the pipe.

[0049] When the high-temperature section of the heat pipe 5 receives heat, the working fluid in the high-temperature section evaporates into gas and moves through the hollow section of the pipe to the low-temperature section. The working fluid that moves to the low-temperature section then condenses and returns to liquid, and is absorbed by the inner wall of the pipe through the capillary action of the wick and returns to the high-temperature section. By transporting heat from the high-temperature section to the low-temperature section in this way, the heat pipe 5 can transfer heat quickly.

[0050] When heat transfers through the heat pipe 5, gas moving from the high temperature area to the low temperature area tends to move upward, in the opposite direction to gravity, while liquid returning from the low temperature area to the high temperature area tends to move downward, in the direction of gravity. For this reason, the heat pipe 5 can be said to perform particularly well (have higher thermal conductivity) when transferring heat upward.

[0051] Generally, the thermal conductivity of stainless steel is about 15 [W / m K], that of aluminum is about 200 [W / m K], and that of copper is about 400 [W / m K], whereas that of the heat pipe 5 is about 4000 to 100,000 [W / m K]. In this way, the heat pipe 5 has a much higher thermal conductivity than stainless steel, aluminum, or copper.

[0052] 1, the heat pipe 5 of this embodiment includes a main pipe 51 extending along each tank 3, and a common pipe 52 connected in a thermally conductive manner to each of the safety valves 1 of the two tanks 3. The common pipe 52 of this embodiment extends along the gas supply pipe 28. That is, the common pipe 52 is laid along the vehicle width direction D2 so as to connect the safety valves 1 attached to the front ends 3f of the two tanks 3 to each other.

[0053] On the other hand, the main pipe 51 extends from the safety valve 1 attached to the ends 3f, 3r along the middle portion 3c of each tank 3. More specifically, the main pipe 51 curves in an arc from the safety valve 1 along the hemispherical ends 3f, 3r, and then extends straight along the cylindrical middle portion 3c parallel to the tank center 3d. The main pipe 51 is provided close to the outer surface of the tank 3 so as not to protrude from the tank 3.

[0054] 3, the main pipe 51 of this embodiment is provided in the space between the chassis frame 22 and the tank 3. More specifically, the main pipe 51 is provided at the same height as the side rails 26, outward of the side rails 26 in the vehicle width direction D2 and inward of the tank center 3d in the vehicle width direction D2. Here, the main pipe 51 provided above (at a higher position than) the tank center 3d is shown as an example.

[0055] The main pipe 51 is fixed, for example, via a clamp or bracket (not shown) to the mount 38 or stay 39 that fixes the tank 3 to the chassis frame 22. However, the structure for fixing the main pipe 51 is not limited to this. The main pipe 51 in this embodiment is provided in the space between the mount 38 fixed to the side rail 26 and the tank 3.

[0056] As shown by the two-dot chain line in Fig. 3, instead of or in addition to the above-mentioned position, the main pipe 51 may be provided in the space between the fan 9 (or the heat exchanger 4) and the tank 3. More specifically, the main pipe 51 may be laid outward of the tank center 3d in the vehicle width direction D2 so as to run along the tank 3. The main pipe 51 shown by the two-dot chain line in Fig. 3 is provided below (at a lower position) than the tank center 3d. Such a main pipe 51 extends downward from the safety valve 1 attached to the ends 3f, 3r of each tank 3 and then extends along the intermediate portion 3c.

[0057] As shown by the two-dot chain line in Figure 3, the safety device 10 may further include a protective member 8 that covers the main pipe 51 (heat pipe 5). The protective member 8 is formed in a plate or lattice shape with a large number of holes so that the heat pipe 5 is not easily affected by ambient heat. By covering at least a portion of the heat pipe 5, the protective member 8 has the function of protecting the heat pipe 5 from a collision load, for example, during a collision of the vehicle 2. For the main pipe 51 that is located outward of the tank center 3d in the vehicle width direction D2 as described above, the protective member 8 may be provided to cover the main pipe 51 from the outside in the vehicle width direction D2 to ensure protection against a load from the outside in the vehicle width direction D2.

[0058] As shown in Fig. 4, the safety valve 1 may further have a housing hole 15 (first connection portion) formed in the housing 6 as a connection structure between the safety valve 1 and the heat pipe 5. The housing hole 15 shown in Fig. 4 is a hole formed in a portion of the housing 6 adjacent to the cylinder 12. Here, a housing hole 15 formed in a portion of the main body 13 of the housing 6 near the cap 14 is shown as an example. Note that the safety valve 1 shown in Fig. 4 and Figs. 5 to 7 described below has a different shape of the main body 13 from that shown in Fig. 2, but the essential functional elements (plunger 11, cylinder 12, etc.) are configured in the same way.

[0059] The heat pipe 5 is connected to the housing hole 15. More specifically, the heat pipe 5 is fixed in contact with the wall surface of the housing hole 15 in the main body 13. As a result, the heat received by the heat pipe 5 is transferred to the cylinder 12 via the housing 6. In order to increase the thermal conductivity from the heat pipe 5 to the cylinder 12, it is preferable that the housing hole 15 is formed as close as possible to the cylinder 12, and that a large contact area between the heat pipe 5 and the housing 6 is ensured.

[0060] Instead of or in addition to the connection structure shown in Fig. 4, the safety device 10 may include a collar 7 attached to the housing 6, as shown in Fig. 5. The collar 7 is made of a material having a higher thermal conductivity than the housing 6. For example, if the housing 6 is made of stainless steel, the collar 7 may be made of copper or aluminum. Fig. 5 illustrates an example of the collar 7 attached to the cap 14 of the housing 6.

[0061] The collar 7 has an annular mounting portion 7a that fits onto the cap 14 of the housing 6, an arm portion 7b that extends radially outward from the mounting portion 7a, and a collar hole 16 (second connection portion) formed in the arm portion 7b. The collar hole 16 shown in Figure 5 is a hole formed in a portion of the collar 7 adjacent to the cylinder 12. Here, an example is shown in which one collar hole 16 is formed in the approximately trapezoidal arm portion 7b provided on the collar 7.

[0062] The heat pipe 5 is connected to the collar hole 16. More specifically, the heat pipe 5 is fixed in contact with the wall of the collar hole 16 in the collar 7. This allows heat received by the heat pipe 5 to be transferred to the cylinder 12 via the collar 7 and the housing 6. To improve thermal conductivity from the heat pipe 5 to the cylinder 12, it is preferable to form the collar hole 16 as close to the cylinder 12 as possible and to ensure large contact areas between the heat pipe 5 and the collar 7 and between the collar 7 and the housing 6. Note that the housing hole 15 and the collar hole 16 are not limited to the holes described above, and various shapes that can connect the heat pipe 5 can be used, such as a groove into which the heat pipe 5 can fit.

[0063] When multiple heat pipes 5 are connected to one safety valve 1, for example, as shown in Fig. 6, the arm portion 7b of the collar 7 may be enlarged and multiple collar holes 16 may be formed in the arm portion 7b. In this way, if the collar 7 has multiple collar holes 16, it becomes possible to connect multiple main pipes 51 or a combination of a main pipe 51 and a common pipe 52 to one safety valve 1. Alternatively or in addition to this, multiple housing holes 15 may be formed in the housing 6, making it possible to connect multiple heat pipes 5 to one safety valve 1.

[0064] If the housing 6 has a low thermal conductivity, a connecting material (interface) for transferring heat may be provided between the housing hole 15 and the cylinder 12 or between the collar 7 and the cylinder 12. Similar to the collar 7, such connecting material is made of a material with a higher thermal conductivity than the housing 6.

[0065] Alternatively, as shown in Fig. 7, multiple heat pipes 5 may be connected to each other by a thermally conductive connecting block 17. The connecting block 17 is made of a material with relatively high thermal conductivity (such as copper or aluminum). Fig. 7 shows an example in which a main pipe 51 and a common pipe 52 are connected to each other by the connecting block 17 near the boundary between the front end 3f and the middle portion 3c of the tank 3. In this case, the common pipe 52 is connected to the safety valve 1 via a part of the main pipe 51 and the connecting block 17 in a manner that allows thermal conductivity. In this way, the common pipe 52 only needs to be connected to the safety valve 1 in a manner that allows thermal conductivity, and does not have to be directly connected to the safety valve 1.

[0066] [1-3. Modified Examples] The mounting posture and mounting position of the tank 3 on the vehicle 2 are not limited to the above example. For example, as shown as modified examples in Figures 8 to 11, the tank 3 may be installed between the cab 21 and the rear body 29 of the vehicle 2. In Figures 8 to 11, elements that are the same as or correspond to elements already described are given the same reference numerals, and duplicated explanations will be omitted below.

[0067] The vehicle 2 of each modified example includes a tank box 30 arranged along the back surface of the cab 21. A plurality of tanks 3 are housed inside the tank box 30. In the first modified example shown in FIG. 8 , the tank 3 is a horizontally mounted tank installed with the tank center 3d (only one tank is marked with a reference numeral in FIG. 8 ) extending horizontally. More specifically, each tank 3 of the first modified example is mounted on the vehicle 2 with the tank center 3d extending along the vehicle width direction D2. The plurality of tanks 3 are lined up inside the tank box 30 in the vehicle height direction D3.

[0068] The heat pipe 5 in each modified example is provided in the space between the rear body 29 and the tank 3. As shown in Fig. 9, the main pipe 51 in the first modified example extends downward and rearward from the safety valve 1 attached to the ends 3f, 3r of each tank 3, and then extends along the intermediate portion 3c. In this manner, the main pipe 51 is provided below (at a lower position) and rearward (toward the rear body 29) of the tank center 3d. Note that in Figs. 9 to 11, the tank box 30 is shown in a see-through state (with two-dot chain lines), and the rear body 29 and other structures not necessary for explanation are omitted, and only some of the multiple components are denoted by reference numerals.

[0069] 9 , the common pipe 52 of the first modified example extends along the vehicle height direction D3 to correspond to the multiple tanks 3 lined up in the vehicle height direction D3. The common pipe 52 is connected to each of the main pipes 51 via the connecting blocks 17. As a result, the common pipe 52 is connected to each of the multiple safety valves 1 attached to the multiple tanks 3 lined up in the vehicle height direction D3 in a thermally conductive manner via the connecting blocks 17 and the main pipes 51. The common pipe 52 of this modified example preferably extends from a height position below the bottom end of the lowest tank 3 to a height position above the top end of the highest tank 3 so as to cover the entire area of ​​the multiple tanks 3 in the vehicle height direction D3.

[0070] 9 illustrates one common pipe 52 provided at approximately the center of each tank 3 in the vehicle width direction D2 and rearward of the tank center 3d (toward the rear body 29). However, the position and number of common pipes 52 are not limited to this. For example, the common pipe 52 may be provided at a position biased to either the left or right side of each tank 3, or multiple common pipes 52 may be arranged at intervals in the vehicle width direction D2.

[0071] 10 shows a second modified example, in which the common pipe 52 is directly connected to the safety valve 1 attached to each tank 3. Here, one common pipe 52 is shown as an example, which is directly connected to the safety valve 1 attached to one end 3r of each tank 3 (the right end 3r in FIG. 10). Alternatively or in addition to this, a common pipe 52 may be provided which is directly connected to the safety valve 1 attached to the other end 3f of each tank 3 (the left end 3f in FIG. 10). The position of such a common pipe 52 can be changed as appropriate depending on the position of the safety valve 1.

[0072] When the common pipe 52 is directly connected to the safety valve 1 as in this modified example, part or all of the main pipe 51 may be omitted. For example, as shown in Fig. 10, the main pipe 51 may be provided only for the tank 3 located at the lowest position. In addition, for example, as shown by the two-dot chain line in Fig. 10, the main pipe 51 may be provided for the tank 3 located at the highest position.

[0073] As shown in Fig. 11 as a third modified example, the tank 3 mounted on the vehicle 2 may be a vertically mounted tank in which the tank center 3d extends vertically (in the vehicle height direction D3). When distinguishing between a pair of ends 3f, 3r of the tank 3 arranged in this manner, the upper end 3f is also referred to as the upper end 3f and the lower end 3r is also referred to as the lower end 3r. Fig. 11 shows an example in which multiple vertically mounted tanks 3 are lined up inside a tank box 30 in the vehicle width direction D2.

[0074] In this modified example, the safety valve 1 is attached only to the upper end 3f of each tank 3. The main pipe 51 extends diagonally downward (rearward and downward in this modified example) from the safety valve 1 attached to the upper end 3f of each tank 3, and then extends along the intermediate portion 3c. The main pipe 51 extends to the vicinity of the lower end 3r of the tank 3 where the safety valve 1 is not attached. Here, the main pipe 51 is provided rearward of the tank center 3d (toward the rear body 29) as an example.

[0075] Furthermore, the common pipe 52 of the third modified example extends along the vehicle width direction D2 in correspondence with the plurality of tanks 3 lined up in the vehicle width direction D2, and is connected to each of the main pipes 51 via the connecting blocks 17. As a result, the common pipe 52 is connected via the main pipes 51 to each of the plurality of safety valves 1 attached to the plurality of tanks 3 lined up in the vehicle width direction D2 in a manner that allows thermal conduction.

[0076] 11 illustrates one common pipe 52 provided slightly above (at a higher position than) the lower end 3r of the tank 3. However, the common pipe 52 may be provided, for example, at approximately the center of the main pipe 51 in the vehicle height direction D3, or multiple common pipes 52 may be arranged at intervals in the vehicle height direction D3. Note that, in this modification as well, it is preferable that the common pipe 52 extend over a length equal to or greater than the distance between the left and right ends of the multiple tanks 3 so as to cover the entire area of ​​the multiple tanks 3 in the vehicle width direction D2.

[0077] [2. Actions and Effects] (1) According to the safety device 10, the heat pipe 5 is connected to the safety valve 1, which releases high-pressure gas from the inside of the tank 3 to the outside as the temperature rises, and heat can be transferred to the safety valve 1 through the heat pipe 5, which has a higher thermal conductivity than stainless steel, copper, aluminum, etc. As a result, even in the event of ignition at a location far from the safety valve 1, for example, heat is transferred quickly and efficiently from the ignition location to the safety valve 1 through the heat pipe 5, so that the safety valve 1 operates as the temperature rises, and the high-pressure gas can be appropriately released.

[0078] Therefore, the safety device 10 allows the safety valve 1 to operate more appropriately. In other words, because the heat pipe 5, which has excellent thermal conductivity, is extended, heat sensitivity is improved over a wide area, and temperature increases can be transmitted to the safety valve 1 without increasing the number of safety valves 1. Therefore, an increase in the number of safety valves 1 is suppressed, and costs can be suppressed. Furthermore, since the heat pipe 5 is a heat transfer device for transmitting heat to the safety valve 1 and high-pressure gas does not flow through it, even if it is deformed or damaged, high-pressure gas leakage will not occur. Therefore, even if an impact is input, for example, during a collision of the vehicle 2, leakage of high-pressure gas can be suppressed.

[0079] (2) The main pipe 51 extends from the safety valve 1 attached to at least one of the hemispherical ends 3f, 3r of the tank 3 along the cylindrical middle portion 3c, allowing heat to be transferred to the safety valve 1 through the main pipe 51 even when the temperature rises in the middle portion 3c of the tank 3. Therefore, for example, when the safety valve 1 is attached to at least one of the ends 3f, 3r of the tank 3, the safety valve 1 can be appropriately activated even when the temperature rises near the middle portion 3c of the tank 3. In other words, even without providing an additional safety valve 1 in the middle portion 3c of the tank 3, the main pipe 51 allows the safety valve 1 attached to at least one of the ends 3f, 3r of the tank 3 to be activated when the temperature rises near the middle portion 3c of the tank 3. Therefore, high-pressure gas can be appropriately released from the tank 3 when the temperature rises while suppressing cost increases.

[0080] (3) For example, as shown in Figures 9 and 10, if the main pipe 51 extends downward from the safety valve 1 attached to the ends 3f, 3r of the horizontally placed tank 3 and then extends along the middle portion 3c, the main pipe 51 can be extended along the middle portion 3c of the tank 3 at a position lower than the safety valve 1. With such a main pipe 51, the working fluid (gas) evaporated by heat near the middle portion 3c of the tank 3 moves upward due to the characteristics of the heat pipe 5, and heat can be transferred to the safety valve 1. In other words, since the direction of heat transfer through the main pipe 51 to the safety valve 1 is upward, heat can be transferred to the safety valve 1 more quickly and efficiently through the main pipe 51. Therefore, the safety valve 1 can be operated more appropriately when the temperature rises near the middle portion 3c of the horizontally placed tank 3.

[0081] (4) As shown in Figure 11, if the main pipe 51 extends obliquely downward from the safety valve 1 attached to the upper end 3f of the vertically placed tank 3 and then extends along the middle portion 3c, the main pipe 51 can be extended along the middle portion 3c of the tank 3 at a position lower than the safety valve 1. With such a main pipe 51, the heat is transferred upward to the safety valve 1 as described above, and therefore heat can be transferred more quickly and efficiently through the main pipe 51 to the safety valve 1. Therefore, the safety valve 1 can operate more appropriately when the temperature rises near the middle portion 3c of the vertically placed tank 3.

[0082] Furthermore, if the main pipe 51 is extended to the vicinity of the lower end 3r of the vertically placed tank 3, when the temperature near the lower end 3r rises, heat can be transmitted through the main pipe 51 to the safety valve 1 attached to the upper end 3f, even without providing a safety valve 1 at the lower end 3r. This reduces the number of safety valves 1, further suppressing cost increases.

[0083] (5) As shown in Figure 3, if the heat pipe 5 is provided in the space between the chassis frame 22 and the tank 3 located further outward in the vehicle width direction D2, the heat pipe 5 can be protected by the tank 3 against an impact input from the outside in the vehicle width direction D2 during a side collision, for example. This reduces the risk of damage to the heat pipe 5 during a side collision of the vehicle 2.

[0084] (6) As shown in Figures 8 to 11, if the heat pipe 5 is provided in the space between the rear body 29 and the tank 3 installed between the cab 21 and the rear body 29, the heat pipe 5 can be protected by the tank 3 against an impact input from the front during a frontal collision, for example. This reduces the risk of damage to the heat pipe 5 during a frontal collision of the vehicle 2.

[0085] (7) By using a common pipe 52 thermally conductively connected to each of the safety valves 1 attached to the multiple tanks 3, heat can be transferred to each of the safety valves 1 attached to the multiple tanks 3 through the common pipe 52. As a result, even in the event of a fire at a location far from some of the safety valves 1, heat can be transferred from the fire location to each safety valve 1 through the common pipe 52. As a result, each safety valve 1 operates in response to a temperature rise, allowing the high-pressure gas to be appropriately released from the inside to the outside of each tank 3. Therefore, in a vehicle 2 equipped with multiple tanks 3, if a temperature rise occurs near one tank 3, not only the safety valve 1 attached to that tank 3 but also the safety valves 1 attached to the other tanks 3 can operate more appropriately. This effectively prevents secondary damage.

[0086] As shown in Fig. 9, if the common pipe 52 is connected to the safety valve 1 via the main pipe 51, heat can be transferred from the common pipe 52 to the safety valve 1 via the main pipe 51, and the common pipe 52 does not need to be directly connected to the safety valve 1, which increases the degree of freedom in arranging the common pipe 52. On the other hand, as shown in Fig. 10, if the common pipe 52 is directly connected to the safety valve 1, heat can be transferred more quickly and reliably from the common pipe 52 to the safety valve 1, allowing the safety valve 1 to operate more appropriately.

[0087] (8) As shown in Figure 1, if a common pipe 52 is installed along the gas supply pipe 28 for sending high-pressure gas to a specified destination, when the temperature rises near the gas supply pipe 28, heat can be transferred to each of the multiple safety valves 1 through the common pipe 52. As a result, in the event of a fire near the gas supply pipe 28, for example, each safety valve 1 will operate in response to the rise in temperature, allowing the high-pressure gas to be appropriately released from the inside to the outside of each tank 3. In addition, if the common pipe 52 is laid along the existing gas supply pipe 28, the common pipe 52 can be easily installed.

[0088] (9) As shown in Figures 9 and 10, if a common pipe 52 extending along the vehicle height direction D3 is connected in a heat-conductive manner to each of the safety valves 1 attached to the plurality of tanks 3 lined up in the vehicle height direction D3, the common pipe 52 can be appropriately applied to the tanks 3 lined up in the vehicle height direction D3. Therefore, when the temperature rises at any position in the vehicle height direction D3, heat can be transmitted to each safety valve 1 through the common pipe 52. Therefore, each safety valve 1 of the tanks 3 lined up in the vehicle height direction D3 can be more appropriately operated.

[0089] (10) As shown in Figure 11, if a common pipe 52 extending along the vehicle width direction D2 is connected in a manner that allows heat conduction to each of the safety valves 1 attached to the plurality of tanks 3 lined up in the vehicle width direction D2, the common pipe 52 can be appropriately applied to the tanks 3 lined up in the vehicle width direction D2. Therefore, when the temperature rises at any position in the vehicle width direction D2, heat can be transmitted to each safety valve 1 through the common pipe 52. Therefore, each safety valve 1 of the tanks 3 lined up in the vehicle width direction D2 can be more appropriately operated.

[0090] (11) As shown in Figure 4, if the heat pipe 5 is connected to the housing hole 15 adjacent to the cylinder 12 that opens the discharge port 6d in the safety valve 1 as the temperature rises, heat is more easily transferred from the heat pipe 5 to the cylinder 12, allowing the safety valve 1 to operate more appropriately. That is, by directly connecting the heat pipe 5 to the housing 6 of the safety valve 1, heat can be transferred well from the heat pipe 5 to the cylinder 12 via the housing 6. In addition, since the heat pipe 5 can be connected simply by forming a hole or groove in the existing housing 6, manufacturing costs can be reduced and the number of heat pipes 5 can be flexibly increased or decreased.

[0091] (12) As shown in Figures 5 and 6, if the heat pipe 5 is connected to the collar hole 16 adjacent to the cylinder 12 in the collar 7 attached to the housing 6 of the safety valve 1, heat can be more easily transferred from the heat pipe 5 to the cylinder 12, allowing the safety valve 1 to operate more appropriately. In other words, by connecting the heat pipe 5 to the housing 6 via the collar 7, which has a higher thermal conductivity than the housing 6 of the safety valve 1, heat can be transferred well from the heat pipe 5 to the cylinder 12 via the collar 7 and the housing 6. Furthermore, since the heat pipe 5 can be connected simply by attaching the collar 7 to the existing housing 6, the existing housing 6 can be used as is, and by using the collar 7, which is an add-on part, the number of heat pipes 5 can be flexibly increased or decreased.

[0092] (13) As shown in Figure 3, if the heat pipe 5 is covered with a protective member 8 formed in a plate or lattice shape with many holes, the protective member 8 can protect the heat pipe 5 while still allowing heat from the surroundings to be transferred to the heat pipe 5. Therefore, even if an impact is applied to the heat pipe 5 during a collision of the vehicle 2, deformation or damage to the heat pipe 5 can be suppressed. This allows the safety valve 1 to operate more appropriately.

[0093] (14) If the safety device 10 is applied to the tank 3, which is a hydrogen tank mounted on the vehicle 2, which is a fuel cell vehicle, the safety valve 1 operates more appropriately as described above, thereby making it possible to appropriately release hydrogen gas from the inside of the tank 3 to the outside. Therefore, it is possible to appropriately respond to temperature increases in the fuel cell vehicle.

[0094] [3. Other] The configurations of the above-described embodiments and modified examples may be combined as appropriate. For example, in the modified examples shown in Figures 8 to 11, the common pipe 52 may be extended along a gas supply pipe (not shown) connected to multiple tanks 3. Furthermore, in the modified examples shown in Figures 8 to 11, the collar 7 shown in Figures 5 and 6 may be applied to the connection structure between the safety valve 1 and the heat pipe 5.

[0095] The shape, number, and arrangement of the tanks 3 mounted on the vehicle 2 are not limited to the above example. For example, only one tank 3 may be mounted on the vehicle 2. In this case, the common pipe 52 is omitted. Furthermore, the high-pressure gas stored inside the tank 3 may be any fuel for the vehicle 2 and is not limited to hydrogen gas. In other words, the vehicle 2 is not limited to a fuel cell vehicle.

[0096] The safety valve 1 may be attached to a location other than the ends 3f, 3r of the tank 3, or may be attached to only one of the ends 3f, 3r. The specific structure of the safety valve 1 is not limited to that shown in Fig. 2. For example, the sensing portion of the safety valve 1 that opens the discharge port 6d in response to a temperature rise may be formed of a member other than the cylinder 12 described above.

[0097] The shape and arrangement of the heat pipe 5 are not limited to the above example, and may be changed as appropriate depending on the shape and arrangement of the tank 3 and the structure and arrangement of the safety valve 1. For example, the main pipe 51 may extend upward or horizontally from the safety valve 1 attached to the ends 3f, 3r of the tank 3 and then extend along the intermediate portion 3c. Furthermore, the common pipe 52 may be provided to extend along a discharge pipe that discharges the high-pressure gas discharged from the safety valve 1 to the outside of the vehicle 2, instead of the gas supply pipe 28. Note that in the safety device 10, either the main pipe 51 or the common pipe 52 may be omitted.

[0098] The above-described configuration of the collar 7 is one example. The collar 7 may be formed in an appropriate shape depending on the shape of the housing 6 of the safety valve 1, the position of the sensing unit, and the like. The collar 7 may also be attached to a location on the housing 6 different from the cap 14. The protective member 8 illustrated in FIG. 3 is applicable to various heat pipes 5. For example, the protective member 8 may be provided so as to cover the common pipe 52. The protective member 8 may also be applied to the various heat pipes 5 illustrated in FIGS. 9 to 11. Furthermore, the protective member 8 may be applied only to a portion of the heat pipe 5 to which an impact may be applied.

[0099] [4. Supplementary Notes] Supplementary notes regarding the above embodiments are disclosed below.

[0100] (Supplementary Note 1) A safety device for a high-pressure gas tank that stores high-pressure gas as a vehicle fuel therein, comprising: a safety valve attached to the high-pressure gas tank, which releases the high-pressure gas from the inside of the high-pressure gas tank to the outside as the temperature rises; and a heat pipe connected to the safety valve, which transfers heat by evaporation and condensation of a working fluid sealed inside and by capillary action of a wick provided on the inner wall.

[0101] (Supplementary Note 2) The safety device for a high-pressure gas tank according to Supplementary Note 1, characterized in that the high-pressure gas tank has a cylindrical middle portion and a pair of hemispherical end portions formed on either side of the middle portion, the safety valve is attached to at least one of the end portions, and the heat pipe includes a main pipe extending from the safety valve attached to the end portion along the middle portion.

[0102] (Supplementary Note 3) The high-pressure gas tank safety device according to Supplementary Note 2, characterized in that the high-pressure gas tank is mounted on the vehicle with the center of the middle section extending horizontally, and the main pipe extends downward from the safety valve attached to the end and then along the middle section.

[0103] (Supplementary Note 4) The safety device for a high-pressure gas tank according to Supplementary Note 2, characterized in that: the high-pressure gas tank is mounted on the vehicle in an orientation in which the center of the middle section extends vertically; the safety valve is attached to the upper end section; and the main pipe extends obliquely downward from the safety valve attached to the end section and then extends along the middle section.

[0104] (Appendix 5) The safety device for a high-pressure gas tank according to any one of Appendices 1 to 4, characterized in that the high-pressure gas tank is installed rearward of the cab of the vehicle and outward in the vehicle width direction from a chassis frame, and the heat pipe is provided in a space between the chassis frame and the high-pressure gas tank.

[0105] (Appendix 6) The safety device for a high-pressure gas tank according to any one of Appendices 1 to 4, characterized in that the high-pressure gas tank is installed between a cab and a rear body of the vehicle, and the heat pipe is provided in a space between the rear body and the high-pressure gas tank.

[0106] (Supplementary Note 7) A safety device for a high-pressure gas tank according to any one of Supplementary Notes 1 to 6, characterized in that the safety valve is attached to each of a plurality of the high-pressure gas tanks, and the heat pipe includes a common pipe connected to each of the safety valves in a thermally conductive manner.

[0107] (Supplementary Note 8) The safety device for a high-pressure gas tank according to Supplementary Note 7, characterized in that the common pipe extends along gas supply pipes connected to a plurality of the high-pressure gas tanks in order to send the high-pressure gas to a predetermined destination.

[0108] (Supplementary Note 9) The safety device for a high-pressure gas tank according to Supplementary Note 7 or 8, characterized in that the common pipe extends along the vehicle height direction and is thermally conductively connected to each of the safety valves attached to the plurality of high-pressure gas tanks lined up in the vehicle height direction.

[0109] (Supplementary Note 10) The safety device for a high-pressure gas tank according to Supplementary Note 7 or 8, characterized in that the common pipe extends along the vehicle width direction and is thermally conductively connected to each of the safety valves attached to a plurality of the high-pressure gas tanks lined up in the vehicle width direction.

[0110] (Appendix 11) The safety device for a high-pressure gas tank according to any one of Appendices 1 to 10, characterized in that the safety valve has a sensing part that opens a discharge port for discharging the high-pressure gas to the outside as the temperature rises, a housing that accommodates the sensing part, and a first connecting part that is a hole or groove formed in a part of the housing adjacent to the sensing part, and the heat pipe is connected to the first connecting part.

[0111] (Appendix 12) The safety valve has a sensing part that opens a discharge port for discharging the high-pressure gas to the outside as the temperature rises, and a housing that accommodates the sensing part, and further comprises a collar that is made of a material with a higher thermal conductivity than the housing and is attached to the housing, and has a second connecting part that is a hole or groove formed in a position adjacent to the sensing part, and the heat pipe is connected to the second connecting part.

[0112] (Appendix 13) The safety device for a high-pressure gas tank according to any one of Appendices 1 to 12, further comprising a protective member formed in a plate or lattice shape with a large number of holes formed therein, the protective member covering the heat pipe.

[0113] (Appendix 14) The safety device for a high-pressure gas tank according to any one of Appendices 1 to 13, characterized in that the vehicle is a fuel cell vehicle that drives a driving motor with power from a fuel cell, and the high-pressure gas tank is a hydrogen tank that stores hydrogen gas as the high-pressure gas therein.

[0114] REFERENCE SIGNS LIST 1 Safety valve 2 Vehicle (fuel cell vehicle) 3 High-pressure gas tank (hydrogen tank) 3A First tank 3B Second tank 3c Middle part 3d Tank center (center of middle part) 3f End (front end, upper end) 3r End (rear end, lower end) 4 Heat exchanger 5 Heat pipe 6 Housing 6a Inlet port 6b Outlet port 6c Gas passage 6d Discharge port 6e Discharge passage 7 Collar 7a Mounting part 7b Arm part 8 Protective member 9 Fan 10 Safety device (safety device for high-pressure gas tank) 11 Plunger 12 Cylinder (sensing part) 13 Main body part 14 Cap 15 Housing hole (first connection part) 16 Collar hole (second connection part) 17 Connecting block 18 Spring 21 Cab 22 Chassis frame 23 Fuel cell 24 Motor 25 High-voltage battery 26 Side rail 27 Cross member 28 Gas supply pipe 29 Rear body 30 Tank box 31 Downstream pipe 32 Side cover 34 Front wheel 35 Rear wheel 37 Outer surface 38 Mount 39 Stay 51 Main pipe 52 Common pipe D1 Vehicle length direction (front-to-rear direction) D2 Vehicle width direction (left-to-right direction) D3 Vehicle height direction (up-down direction)

Claims

1. A safety device for a high-pressure gas tank which stores high-pressure gas as a vehicle fuel therein, comprising: a safety valve attached to the high-pressure gas tank and which releases the high-pressure gas from the inside of the high-pressure gas tank to the outside as the temperature rises; and a heat pipe connected to the safety valve and which transfers heat by evaporation and condensation of the working fluid sealed inside and by the capillary phenomenon of a wick provided on the inner wall.

2. The safety device for a high-pressure gas tank as described in claim 1, characterized in that the high-pressure gas tank has a cylindrical middle section and a pair of hemispherical end sections formed on either side of the middle section, the safety valve is attached to at least one of the end sections, and the heat pipe includes a main pipe extending from the safety valve attached to the end section along the middle section.

3. The high-pressure gas tank safety device according to claim 2, characterized in that the high-pressure gas tank is mounted on the vehicle with the center of the middle section extending horizontally, and the main pipe extends downward from the safety valve attached to the end and then along the middle section.

4. A safety device for a high-pressure gas tank as described in claim 2, characterized in that: the high-pressure gas tank is mounted on the vehicle with the center of the middle section extending vertically; the safety valve is attached to the upper end section; and the main pipe extends diagonally downward from the safety valve attached to the end section and then extends along the middle section.

5. A safety device for a high-pressure gas tank as described in claim 1, characterized in that the high-pressure gas tank is installed rearward of the cab of the vehicle and outward in the vehicle width direction from the chassis frame, and the heat pipe is provided in the space between the chassis frame and the high-pressure gas tank.

6. The safety device for a high-pressure gas tank as described in claim 1, characterized in that the high-pressure gas tank is installed between a cab and a rear body of the vehicle, and the heat pipe is provided in the space between the rear body and the high-pressure gas tank.

7. A safety device for a high-pressure gas tank as described in claim 1, characterized in that the safety valve is attached to each of a plurality of the high-pressure gas tanks, and the heat pipe includes a common pipe thermally connected to each of the safety valves.

8. The high-pressure gas tank safety device according to claim 7, characterized in that the common pipe extends along a gas supply pipe connected to a plurality of the high-pressure gas tanks in order to send the high-pressure gas to a specified supply destination.

9. A safety device for a high-pressure gas tank as described in claim 7, characterized in that the common pipe extends along the vehicle height direction and is thermally connected to each of the safety valves attached to a plurality of the high-pressure gas tanks lined up in the vehicle height direction.

10. A safety device for a high-pressure gas tank as described in claim 7, characterized in that the common pipe extends along the vehicle width direction and is thermally connected to each of the safety valves attached to a plurality of the high-pressure gas tanks lined up in the vehicle width direction.

11. The safety device for a high-pressure gas tank as described in claim 1, characterized in that the safety valve has a sensing part that opens a discharge port for discharging the high-pressure gas to the outside as the temperature rises, a housing that contains the sensing part, and a first connection part that is a hole or groove formed in a portion of the housing adjacent to the sensing part, and the heat pipe is connected to the first connection part.

12. The safety valve of claim 1, further comprising a collar made of a material having a higher thermal conductivity than the housing, attached to the housing, and having a second connecting portion which is a hole or groove formed in a position adjacent to the sensing portion, the safety device for a high-pressure gas tank being characterized in that the heat pipe is connected to the second connecting portion, the collar being formed of a material having a higher thermal conductivity than the housing, the collar being attached to the housing, and the collar being formed of a material having a higher thermal conductivity than the housing, the collar being attached to the housing, ... in a position adjacent to the sensing portion, the heat pipe being connected to the second connecting portion.

13. A safety device for a high-pressure gas tank as described in claim 1, further comprising a protective member formed in a plate or lattice shape with a large number of holes and covering the heat pipe.

14. The safety device for a high-pressure gas tank as described in claim 1, characterized in that the vehicle is a fuel cell vehicle in which a motor for running is driven by power from a fuel cell, and the high-pressure gas tank is a hydrogen tank that contains hydrogen gas as the high-pressure gas therein.

Images