JP6984493B2 - High pressure gas storage tank - Google Patents

Description

The present invention relates to a high pressure gas storage tank.

High-pressure gas storage tanks for storing hydrogen gas are widely used, for example, in vehicles equipped with fuel cells. The high-pressure gas storage tank usually includes a base to which a valve can be attached, a resin liner for accommodating high-pressure hydrogen gas, and a reinforcing layer covering the outer periphery of the liner, and the base is the liner. It is attached to one or both tip openings. An example is described in Patent Document 1. There, blow molding is used to integrate the base with the tip of the liner during molding. In the molding process, a part of the resin that forms the liner enters the concave groove provided on the outer circumference of the base, which prevents the base from inadvertently moving to and from the opening at the tip of the liner. ..

The resin liner heat shrinks in a low temperature environment. In the high-pressure gas storage tank described in Patent Document 1, since the resin for forming the liner is integrally contained in the concave groove provided on the outer periphery of the base, the stress is concentrated at a specific place during the heat shrinkage of the liner. Therefore, careful consideration is required for the shape and dimensions of the concave groove at the time of designing.

Another form of high pressure gas storage tank is described in Patent Document 2. There, injection molding is used to form a cylindrical liner having a folded portion at the tip opening. After molding, the base is press-fitted into the folded portion in the post-work. The mouthpiece has a concave groove in the circumferential direction on the outer peripheral surface, an O-ring is inserted into the concave groove, and a seal line is formed between the inserted O-ring and the inner peripheral surface of the folded portion of the liner. .. In order to maintain the sealing property at the seal line, a metal ring (insert ring) is arranged on the outer peripheral surface of the folded portion corresponding to the seal line.

Japanese Unexamined Patent Publication No. 2014-238110 JP-A-2010-249239

The manufacturing method in which the liner is molded by injection molding and the base is press-fitted into the folded portion in the post-work has a greater degree of freedom in design than the manufacturing method in which the base is integrally fixed to the opening of the liner by blow molding. Become. However, the high-pressure gas storage tank obtained by the former manufacturing method may slip between the liner and the base due to the shrinkage of the liner when placed in a low-temperature low-pressure environment. If this occurs, the posture of the base may become unstable. In extreme cases, the tip of the liner may come off the mouthpiece. In order to avoid this, careful consideration is required for setting the tightening strength with the metal ring placed at the seal line position.

FIG. 3 shows slippage of a seal portion that may occur in a low temperature and low pressure environment in a conventional high pressure gas storage tank. In FIG. 3, the figure on the left side of the central axis O shows the state of the high-pressure gas storage tank 1 at the time of manufacture, that is, the state at normal temperature and pressure, and the figure on the right side of the central axis O shows the state of the high-pressure gas storage tank 1. Shows the state at low temperature and low pressure (for example, −67 ° C./0.1 MPa).

In FIG. 3, reference numeral 2 is a cylindrical liner formed by injection molding and axisymmetric in the circumferential direction, and the central axis O is the central axis of the liner 2. The liner 2 has a folded-back portion 3 at an end portion in the central axis direction, and a base 5 provided with a valve 4 and having a common central axis O is inserted into the folded-back portion 3. The lower end portion of the inserted base 5 is press-fitted into the lower end portion of the folded-back portion 3. A reinforcing layer 6 made of FRP or the like is formed so as to cover the outer peripheral surfaces of the liner 2 and the base 5, ensuring the strength of the high-pressure gas storage tank 1.

A concave groove in the circumferential direction is formed at the lower end portion of the base 5, and the O-ring 7 is inserted into the concave groove. The outer peripheral surface of the lower end portion of the base 5 and the inner peripheral surface of the lower end portion of the folded portion 3 of the liner 2 are in surface contact with each other on the entire peripheral surface, and the O-ring 7 and the inner peripheral surface of the lower end portion of the folded portion 3 are in surface contact with each other. By contact, a seal line is formed there. A metal ring 8 is attached to the outer peripheral surface of the lower end portion of the folded portion 3 corresponding to the seal line.

As shown in the figure on the left side of the central axis O in FIG. 3, at normal temperature and pressure, the outer peripheral surface of the base 5 and the outer surface of the folded portion 3 of the liner 2 are in close contact with each other, and the lower end portion of the base 5 is in close contact with each other. The outer peripheral surface and the inner peripheral surface of the lower end portion of the folded portion 3 are also in close contact with each other. When the high-pressure gas storage tank 1 in this state is placed in a low-temperature low-pressure environment, the resin liner 2 which is axially symmetric in the circumferential direction is as shown by the arrow in the figure on the right side of the central axis O in FIG. , Shrinks in the radial direction and the central axial direction toward the center of the high-pressure gas storage tank 1. Then, between the outer peripheral surface of the lower end portion of the base 5 and the inner peripheral surface of the lower end portion of the folded portion 3 of the liner 2, which also takes into account the frictional force of the press-fitting portion, that is, the tightening force in the radial direction of the metal ring 7. When the frictional force of the liner 2 becomes smaller than the contraction force in the central axis direction, slippage occurs between the two, and as shown in the figure on the right side of the central axis O in FIG. 3, the folded portion 3 of the liner 2 The lower end portion of the above is moved by a distance h while sliding downward from the normal temperature and pressure. When such slippage occurs, the posture of the base 5 becomes unstable, and the sealing property between the liner 2 and the base 5 may be deteriorated.

In the low temperature and low pressure environment of the liner 2 described above, the adiabatic expansion of the hydrogen gas generated when the high pressure hydrogen gas stored in the high pressure gas storage tank 1 at, for example, about 35 to 70 MPa is released from the high pressure gas storage tank 1. Is formed by.

The present invention has been made in view of the above circumstances, and is a high-pressure gas storage tank including at least a base to which a valve can be mounted and a cylindrical liner having a folded portion into which the base is press-fitted at at least one end. Provides a high-pressure gas storage tank that prevents the liner from slipping between the liner and the base even when the liner shrinks in a low-temperature and low-pressure environment, and ensures the stability of the posture of the base. The task is to do.

The high-pressure gas storage tank according to the present invention is a high-pressure gas storage tank including at least a base to which a valve can be mounted and a cylindrical liner having a folded portion into which the base is press-fitted at at least one end. A circumferential seal portion is formed between the inner peripheral surface of the folded portion and the outer peripheral surface of the base press-fitted into the folded portion, and is located outside the center axis direction of the liner with respect to the sealed portion. A concave portion or a convex portion is formed on the outer peripheral surface of the mouthpiece in the circumferential direction, and a convex portion or a concave portion that can be engaged with the concave portion or the convex portion formed on the mouthpiece is formed on the inner peripheral surface of the folded portion. In a normal temperature and pressure environment, the concave portion and the convex portion are in a non-engaged state, and in a low temperature and low pressure environment caused by adiabatic expansion when the stored gas is released, heat shrinks in the direction of the central axis of the folded portion. It is characterized in that the concave portion and the convex portion are in an engageable state.

In the high-pressure gas storage tank according to the present invention, even if the liner undergoes thermal shrinkage in a low-temperature low-pressure environment caused by adiabatic expansion when the stored gas is released, it is possible to prevent the liner from slipping with the mouthpiece. can. Thereby, the stability of the posture of the base is maintained. In addition, there is no particular inconvenience in the press-fitting operation when the base is press-fitted into the liner during the manufacture of the high-pressure gas storage tank.

It is sectional drawing of the vicinity of the base of the high-pressure gas storage tank in the state where the base is press-fitted into the liner constituting the high-pressure gas storage tank, and shows the state at normal temperature and pressure. FIG. 3 is a cross-sectional view showing the vicinity of a base when a high-pressure gas storage tank having the configuration shown in FIG. 1 is in a low-temperature low-pressure environment caused by adiabatic expansion when the stored gas is released. The figure explaining the posture change of the liner between the time of normal temperature and pressure and the time of low temperature and low pressure in the conventional high pressure gas storage tank.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows a cross section of the vicinity of the base 20 in a state where the base 20 is press-fitted into the liner 10 constituting the high-pressure gas storage tank 100 of the present embodiment, and the high-pressure gas storage tank 100 is at normal temperature and pressure. It shows the state at the time. From the state of FIG. 1, a valve (not shown) is attached to the base 20, and the outer peripheral surfaces of the liner 10 and the base 20 are covered with a reinforcing material such as FRP to obtain a high-pressure gas storage tank 100. Here, the normal temperature and pressure is an environment in which the high-pressure gas storage tank 100 is manufactured or an environment in which the high-pressure gas is left as it is in the atmospheric environment without being stored after the manufacture.

The liner 10 is a cylindrical body having a central axis O, and a conical folded portion 11 having the same central axis O is provided at one end or both ends in the central axis direction. The lower end portion 12 of the folded portion 11 has a cylindrical shape, and the inner diameter of the cylindrical lower end portion 12 is smaller than the inner diameter of the main body portion 13 of the liner 10. In this example, the liner 10 is a molded product by injection molding, and as a material, polyamide, ethylene vinyl alcohol copolymer, polyethylene, or the like is used.

A base 20 to which a valve can be mounted is press-fitted into the folded portion 11 of the injection-molded liner 10. In FIG. 1, the valve is not shown. The base 20 has a cylindrical main body portion 21, a seal portion 22 which is a lower end portion of the main body portion 21, and a large-diameter flange portion 23 which is an upper portion of the main body portion 21. The outer diameter of the seal portion 22 is slightly larger than the inner diameter of the cylindrical lower end portion 12 of the folded portion 11 of the liner 10, and the outer diameter of the flange portion 23 is the folded portion 11 and the liner. It is sized to reach the vicinity of the intermediate portion of the connecting portion 14 between the cylindrical main body portion 13 of the 10 and the main body portion 13.

The main body portion 21 of the base 20 is press-fitted into the folded portion 11 of the liner 10 after molding from above in the figure. As a result, the outer peripheral surface of the seal portion 22 and the inner peripheral surface of the cylindrical lower end portion 12 of the folded portion 11 of the liner 10 are in a crimped state. When the flange portion 23 of the base 20 is positioned on the connecting portion 14 of the liner 10, the base 20 is in a state of being attached to the liner 10.

A concave groove 24 in the circumferential direction is formed on the outer peripheral surface of the seal portion 22 of the base 20, and an O-ring 25 having a required dimension is fitted in the concave groove 24. As described above, the inner peripheral surface of the cylindrical lower end portion 12 of the folded portion 11 of the liner 10 is in pressure contact with the outer peripheral surface of the seal portion 22 of the base 20, and the seal line is formed by the pressure contact surface and the O-ring 25. Is formed. In order to ensure effective sealing performance, a metal ring (insert ring) 15 is arranged on the outer peripheral surface of the cylindrical lower end portion 12 of the folded portion 11 of the liner 10 or inside the metal ring. 15 maintains the required pressure contact force on the seal line.

The conical folded-back portion 11 between the lower end portion 12 of the liner 10 and the connecting portion 14 does not touch the outer peripheral surface of the main body portion 21 of the base 20. More specifically, when the base 20 is attached to the liner 10, that is, under normal temperature and pressure, the inner peripheral surface of the folded portion 11 of the liner 10 is not in contact with the outer peripheral surface of the main body portion 21 of the base 20.

A concave groove 26 for engagement in the circumferential direction is formed on the outer peripheral surface of the main body portion 21 which is an outer portion in the central axial direction from the seal portion 22 of the base 20. On the other hand, an engaging convex portion 16 is formed in a portion of the folded portion 11 of the liner 10 facing the engaging concave groove 26. As described above, in the state of normal temperature and pressure, the folded portion 11 of the liner 10 and the main body portion 21 of the base 20 are not in contact with each other, and in that state, the engaging convex portion 16 and the engaging concave groove 26 interact with each other. The engaging convex portion 16 is formed at a position and a size that does not interfere with the above. Therefore, when the base 20 is press-fitted into the liner 10, the engaging concave groove 26 and the engaging convex portion 16 do not interfere with each other, and the base 20 is press-fitted smoothly, which is unexpected to the liner 10. There is no such thing as plastic deformation.

The outer peripheral reinforcing layer 30 (see FIG. 2) is formed by winding a reinforcing material such as FRP around the assembly of the liner 10 and the base 20 shown in FIG. 1 so as to cover the entire outer peripheral surface thereof. As a result, the high-pressure gas storage tank 100 is completed. A high-pressure gas (for example, hydrogen, helium, etc.) is supplied to the inside of the liner 10 via a valve attached to the base 20 to the manufactured high-pressure gas storage tank 100, and the supplied gas is a high-pressure gas. It is stored in the storage tank 100 in a state of, for example, about 35 to 70 MPa.

When the stored high-pressure gas is discharged from the high-pressure gas storage tank 100, the temperature and pressure in the high-pressure gas storage tank 100 are lowered by the discharge. The decrease in temperature is due to the adiabatic expansion of the emitted gas. Although it depends on the type of gas to be stored and the gas release environment, in the case of hydrogen gas, the temperature inside the high-pressure gas storage tank 100 drops to, for example, about −70 ° C., and the pressure inside the high-pressure gas storage tank 100 due to the release. Drops to about 0.1 MPa.

When the temperature inside the high-pressure gas storage tank becomes low, the liner 10 made of resin shrinks in both the axial direction and the radial direction due to thermal deformation. When the inside of the high-pressure gas storage tank is in a high-pressure state, the heat shrinkage of the liner 10 is suppressed to some extent by the pressure inside the high-pressure gas storage tank, but when the inside of the high-pressure gas storage tank is in a low-pressure state, a non-negligible amount of heat shrinkage occurs. Occurs.

FIG. 2 shows a state in which the liner 10 is thermally shrunk in an environment of, for example, −67 ° C./0.1 MPa in the high-pressure gas storage tank 100. As described above, when the liner 10 undergoes thermal shrinkage, the liner 10 shrinks not only in the central axis O direction but also in the radial direction. As shown in FIG. 2, due to heat shrinkage, peeling 40 occurs between the liner 10 and the base 20 and the outer peripheral reinforcing layer 30, and due to the behavior during the shrinkage, the base is press-fitted under normal temperature and pressure. The engaging concave groove 26 formed in the base 20 and the engaging convex portion 16 formed in the liner 10 which did not interfere with each other in the step are engaged with each other in the engaging concave groove 26 formed in the base 20. The combined convex portion 16 is in an engaged state. By the engagement, the shrinkage of the liner 10 in the downward direction in the axial direction is suppressed. As a result, due to heat shrinkage, the frictional force between the outer peripheral surface of the seal portion 22 of the base 20 and the inner peripheral surface of the lower end portion 12 of the folded portion 11 of the liner 10 shrinks toward the central axis O of the liner 10. Even when the force becomes smaller than the force, the behavior of the liner 10 sliding in the axial direction as described with reference to FIG. 3 is prevented. By preventing slipping, the stability of the posture of the base 20 with respect to the liner 10 is well maintained.

In the present invention, the specific values of low temperature and low pressure are not fixed values, but change depending on the shape and capacity of the high pressure gas storage tank, the type of liner material, the type of gas possessed, and the like. It is set for each high-pressure gas storage tank experimentally or by calculation for the actual high-pressure gas storage tank. Further, in consideration of the low temperature and low pressure environment that may occur in the environment where the high pressure gas storage tank is actually used, the gap between the liner 10 and the base 20 shown in FIG. 1 and the engaging concave groove 26 formed therein. The size of the engaging convex portion 16 will be set.
In the above description, the engaging concave groove 26 is formed on the base 20 side and the engaging convex portion 16 is formed on the liner 10 side, respectively. However, the engaging concave groove 26 and the engaging convex portion 16 are formed. The parts may be reversed. However, when the engaging groove 26 is formed in the liner 10, the thickness of the liner 10 becomes thin at that portion, and in some cases, the mechanical strength may be insufficient. Therefore, the modes shown in FIGS. 1 and 2 can be said to be more preferable modes.

100 ... High pressure gas storage tank,
O ... Central axis,
10 ... liner,
11 ... Folded part,
12 ... The lower end of the folded part,
13 ... Liner body,
14 ... Connecting part,
15 ... Metal ring (insert ring),
16 ... Convex part for engagement,
20 ... Mouthpiece,
21 ... The main body of the base,
22 ... Seal part of the base,
23 ... Flange part of the base,
24 ... concave groove,
25 ... O-ring,
26 ... Engagement recess,
30 ... Outer peripheral reinforcement layer,
40 ... Peeling between the liner and the base and the outer peripheral reinforcing layer.

Claims (1)

A high-pressure gas storage tank including at least a base to which a valve can be mounted and a cylindrical liner having a folded portion into which the base is press-fitted at at least one end.
A circumferential sealing portion is formed between the inner peripheral surface of the folded portion of the liner and the outer peripheral surface of the mouthpiece pressed into the folded portion, and the liner is directed toward the central axis of the liner with respect to the sealed portion. A concave portion or a convex portion is formed on the outer peripheral surface of the mouthpiece on the outer side in the circumferential direction, and a convex portion or a concave portion that can engage with the concave portion or the convex portion formed on the mouthpiece is formed on the inner peripheral surface of the folded portion. Is formed,
In a normal temperature and pressure environment, the concave portion and the convex portion are in a non-engaged state, and in a low temperature and low pressure environment caused by adiabatic expansion when the stored gas is released, the concave portion is thermally contracted in the direction of the central axis of the folded portion. A high-pressure gas storage tank characterized in that the convex portion and the convex portion can be engaged with each other.

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