JP7578065B2 - High Pressure Tank - Google Patents

Description

The present invention relates to a high-pressure tank having a liner and a reinforcing layer formed on the outer surface of the liner.

This type of high-pressure tank has been disclosed to include a liner having a cylindrical body with a constant outer diameter and dome sections at both axial ends of the body, a hoop layer formed by winding reinforcing fibers in a hoop shape, and a helical layer formed by winding reinforcing fibers in a helical shape (see Patent Document 1).

JP 2020-169656 A

When a rear-wheel drive vehicle structure equipped with an internal combustion engine and a transmission is directly adopted in the vehicle structure of a fuel cell vehicle (FCV), it is reasonable to install the high-pressure tank described in Patent Document 1 in the floor tunnel where the transmission was installed, since the diameter of the high-pressure tank can be made relatively large. However, the space in the floor tunnel is formed in a tapered shape in which the space is large in the front as seen by the driver seated in the driver's seat, and the space gradually becomes smaller toward the rear. If the high-pressure tank described in Patent Document 1 is installed in this space, there is a problem that an empty space is generated in front of the floor tunnel, resulting in an unused space. On the other hand, if the high-pressure tank is formed in a tapered shape that gradually increases in diameter as it moves along the axial direction in order to effectively utilize the space in the floor tunnel, it is necessary to ensure the mechanical strength of the high-pressure tank.

The present invention was made to solve these problems, and aims to provide a high-pressure tank that can effectively utilize the entire space in a mounting space such as a vehicle floor tunnel, where the diameter gradually expands from a small diameter to a large diameter, while also ensuring mechanical strength.

(1) The high-pressure tank according to the present invention is a high-pressure tank having a liner and a reinforcing layer formed on the outer surface of the liner, the liner having a cylindrical body portion that gradually expands in diameter as it moves along the axial direction, a hemispherical first dome portion that closes the small-diameter end of the body portion, and a hemispherical second dome portion that closes the large-diameter end of the body portion, the reinforcing layer having a hoop layer formed by hoop-wounding reinforcing fibers and a helical layer formed by helically winding the reinforcing fibers, the hoop layer being thicker on the second dome portion side than on the first dome portion side. With this configuration, the high-pressure tank can be installed in the space inside the floor tunnel of a fuel cell vehicle that is configured with a rear-wheel drive vehicle structure equipped with an internal combustion engine and a transmission, since the body portion of the high-pressure tank is gradually expanded in diameter, and the entire space is effectively utilized. In addition, the hoop layer is formed thicker on the second dome portion side than on the first dome portion side, so that the mechanical strength of the large-diameter side of the body portion is ensured.

(2) In the high-pressure tank according to the present invention, the thickness of the hoop layer increases in proportion to the outer diameter of the body portion. This configuration ensures uniform mechanical strength from the small diameter end to the large diameter end of the body portion.

(3) The high-pressure tank according to the present invention is characterized in that a nozzle that communicates between the inside and outside of the high-pressure tank is attached to the first dome portion. This configuration ensures the mechanical strength of the first dome portion formed by helical winding. That is, the number of winding turns of the helical winding is determined so as to ensure the mechanical strength of the large diameter side, so the helical layer of the first dome portion, which has a smaller area, is formed to be thicker than the helical layer of the second dome portion, which has a larger area. As a result, the first dome portion has a higher mechanical strength than the second dome portion. The attachment portion of the nozzle requires high mechanical strength, but the nozzle is attached to the first dome portion, which has a higher mechanical strength.

(4) In the high-pressure tank according to the present invention, the nozzle has a shaft portion that penetrates the reinforcing layer, and a flange portion that expands in diameter from the shaft portion and abuts against the outer wall surface of the first dome portion. With this configuration, the nozzle is attached to the first dome portion in close contact via the flange portion.

(5) In the high-pressure tank according to the present invention, an end boss having a diameter smaller than that of the shaft portion of the nozzle is attached to the second dome portion. This configuration results in ensuring the mechanical strength of the second dome portion. That is, the end boss only has the function of chucking one end of the liner when the liner is set in the filament winding device, and does not require high mechanical strength compared to the nozzle. In addition, the shaft portion of the end boss does not need to have a function of circulating gas, and does not need to penetrate the liner to be attached to the second dome portion, so the diameter of the shaft portion may be relatively small. By making the shaft portion of the end boss have a smaller diameter than the shaft portion of the nozzle, the load on the reinforcing layer of the second dome portion by the end boss is reduced, and the end boss can be attached to the second dome portion, which has a lower mechanical strength than the first dome portion.

The present invention provides a high-pressure tank that can effectively utilize the entire space in a mounting space such as a vehicle floor tunnel, where the diameter gradually expands from a small diameter to a large diameter, while also ensuring mechanical strength.

1A and 1B are diagrams of a high-pressure tank according to an embodiment of the present invention, in which FIG. 1A shows a side view of a high-pressure tank installed in a floor tunnel, and FIG. 1B shows a cross-sectional view of the high-pressure tank cut in a direction perpendicular to the central axis. FIG. 1(b) is a cross-sectional view of a high-pressure tank according to an embodiment of the present invention taken along line AA in FIG. 3A and 3B are diagrams of a nozzle of a high-pressure tank according to an embodiment of the present invention, in which FIG. 3A shows a side view, FIG. 3B shows a front view from B, and FIG. 3C shows a cross-sectional view taken along CC in FIG. 3B. 4A and 4B are diagrams of an end boss of a high-pressure tank according to an embodiment of the present invention, in which FIG. 4A shows a side view, FIG. 4B shows a front view from D, and FIG. 4C shows a cross-sectional view taken along line E-E in FIG. 4B. 5A and 5B are diagrams illustrating a method of winding reinforcing fibers in a high-pressure tank according to an embodiment of the present invention, in which FIG. 5A shows a schematic diagram of hoop winding, and FIG. 5B shows a schematic diagram of helical winding.

A high-pressure tank 10 according to an embodiment of the present invention will be described with reference to the drawings.
1(a) and 1(b), the high-pressure tank 10 according to the embodiment has a liner 11, a nozzle 12, an end boss 13, and a reinforcing layer 14. The high-pressure tank 10 has a property of being difficult for gas to permeate, that is, has so-called gas barrier properties, and is configured so that a high-pressure gas such as hydrogen is supplied to the inside.

The high-pressure tank 10 is installed in a floor tunnel formed in the center of the driver's seat in the left-right direction of the fuel cell vehicle. This fuel cell vehicle has a rear-wheel drive vehicle structure equipped with an internal combustion engine and transmission, that is, the vehicle structure of a vehicle with an internal combustion engine is used as is for a fuel cell vehicle. The floor tunnel is the space where the transmission is installed in a vehicle with an internal combustion engine, and is formed below the floor tunnel top line indicated by the dashed line. This space has a tapered shape that is large in diameter at the front and becomes smaller in diameter toward the rear.

As shown in Figs. 1(b) and 2, the liner 11 is a cylindrical hollow container, and has a body portion 21 that gradually expands in diameter from small to large along the axial direction, a first dome portion 22, and a second dome portion 23. The liner 11 is made of engineering plastics with high mechanical strength, such as polyethylene, polyamide resin (PA), and nylon, and is integrally formed by rotational molding or blow molding.

In addition, the liner 11 may be formed from a light metal such as aluminum instead of engineering plastic. Also, instead of a manufacturing method for integral molding such as rotational molding or blow molding, the liner 11 may be formed by dividing the liner 11 into two parts, molding them separately by injection molding, extrusion molding, or the like, and joining them by a joining method such as infrared welding, laser welding, hot plate welding, vibration welding, or ultrasonic welding.

As shown in Figs. 1(a) and 2, the first dome section 22 is formed in a hemispherical shape and closes the small diameter end of the body section 21. The first dome section 22 has a base mounting section 31 and has a higher mechanical strength than the second dome section 23, as described below. The base mounting section 31 has a higher mechanical strength and the base 12 is mounted on it. The base mounting section 31 has a through hole 32 for allowing gas to flow. The second dome section 23 is formed in a hemispherical shape like the first dome section 22 and closes the large diameter end of the body section 21. The second dome section 23 has an end boss mounting section 33 and the end boss 13 is mounted on the end boss mounting section 33.

As shown in Figures 2, 3(a), 3(b) and 3(c), the nozzle 12 has a shaft portion 41 and a flange portion 42, and the shaft portion 41 and the flange portion 42 are integrally formed from a metal material. A through hole 43 is formed in the shaft portion 41 and the flange portion 42, penetrating in the axial direction. The through hole 43 is connected to the through hole 32 of the nozzle mounting portion 31, and gas flows between the inside and outside of the high-pressure tank 10 via the through hole 32 of the nozzle mounting portion 31.

A valve (not shown), such as a shutoff valve, is attached to the nozzle 12, and the through hole 43 and the through hole 32 are connected or disconnected by the valve. The valve opens when high-pressure gas is supplied to the inside of the high-pressure tank 10, and closes when the gas supply ends. The valve also opens as necessary, and the high-pressure gas filled inside is supplied to the outside via the valve.

The shaft portion 41 is formed in a cylindrical shape with a diameter D1, penetrates the reinforcing layer 14, and protrudes outward in the axial direction of the first dome portion 22. The flange portion 42 is formed in a disk shape that protrudes radially from the shaft portion 41, and is attached to the first dome portion 22 by abutting against the outer wall surface of the base attachment portion 31 of the first dome portion 22.

As shown in Figures 2, 4(a), 4(b) and 4(c), the end boss 13 has a shaft portion 51 and a flange portion 52, and the shaft portion 51 and the flange portion 52 are integrally formed from a metal material.

The shaft portion 51 is formed in a cylindrical shape with a diameter D2 smaller than the diameter D1 of the shaft portion 41 of the base 12, and protrudes through the reinforcing layer 14 to the outside in the axial direction of the second dome portion 23. The flange portion 52 is formed in a disk shape protruding radially from the shaft portion 51, abuts against the end boss attachment portion 33 of the second dome portion 23, and is attached to the second dome portion 23 by, for example, gluing.

The end boss 13 has the function of chucking one end of the liner 11 when the liner 11 is set in the filament winding device, and does not require high mechanical strength compared to the nozzle 12. Therefore, the shaft portion 51 is formed with a diameter D2 smaller than the diameter D1 of the shaft portion 41 of the nozzle 12. In addition, since the shaft portion 51 does not need to pass gas, a through hole penetrating the shaft portion 51 is not required. The end boss 13 has a flange portion 52 attached in close contact with the outer wall surface of the end boss attachment portion 33 of the second dome portion 23.

The nozzle 12 has a hole in the center as a fuel filling and discharging port, and a boss in which a valve is attached. In the liner 11, an end boss 13 is arranged on the opposite side to the nozzle 12. The end boss 13 has a boss in the center for supporting the shaft during filament winding. The hole diameter of the reinforcing layer 14 around the neck of the nozzle 12 is usually larger than the hole diameter of the reinforcing layer 14 around the end boss 13. Therefore, the surface pressure generated on the contact surface between the flange portion 42 of the nozzle 12 and the reinforcing layer 14 is larger than the surface pressure generated on the contact surface between the flange portion 52 of the end boss 13 and the reinforcing layer 14. It is possible to reduce the surface pressure on the nozzle 12 side by ensuring a flange contact area according to the hole area ratio, but this is not practical because the flange diameter of the nozzle 12 becomes large, which causes problems such as increased costs. Based on the above, it is reasonable to install the nozzle 12 on the first dome portion 22 where the reinforcing layer 14 has a large wall thickness.

As shown in Figs. 1(b), 2, 5(a) and 5(b), the reinforcing layer 14 has a hoop layer 61 formed on the outer surface of the liner 11 by hoop-winding the reinforcing fiber F, and a helical layer 62 formed on the outer surface of the liner 11 by helically winding the reinforcing fiber F. The hoop layer 61 and the helical layer 62 are formed, for example, by a filament winding device (not shown) using the filament winding process.

The reinforcing fiber F is formed by impregnating a fiber bundle made of single fibers each having a diameter of, for example, about several μm with an uncured thermosetting resin. Examples of the reinforcing fiber F include carbon fiber reinforced plastics (CFRP) and glass fiber reinforced plastics (GFRP).

Examples of the single fiber include carbon fiber, glass fiber, aramid fiber, alumina fiber, boron fiber, steel fiber, PBO fiber (poly p-phenylene benzobisoxazole fiber), natural fiber, and high-strength polyethylene fiber. Examples of the thermosetting resin include epoxy resin, modified epoxy resin represented by vinyl ester resin, phenol resin, melamine resin, urea resin, unsaturated polyester resin, alkyd resin, polyurethane resin, and thermosetting polyimide resin.

As shown in FIG. 5(a), hoop winding is a method of winding in the circumferential direction of the body portion 21 at a winding angle that is approximately perpendicular to the central axis L of the liner 11. A hoop layer 61 is formed on the body portion by hoop winding. Here, "approximately perpendicular" includes both 90° and an angle of approximately 90° that can be created by shifting the winding position of the reinforcing fibers F so that the reinforcing fibers F do not overlap each other.

Hoop winding is a method of winding reinforcing fibers F to obtain radial strength, and as shown in Figure 2, is a winding method that obtains mechanical strength against stress σθ (MPa) generated in the circumferential direction by internal pressure P (MPa) acting on the body portion 21 of the high-pressure tank 10. If the thickness of the hoop layer 61 at one end T1 of the body portion 21 is ta1, the thickness of the hoop layer 61 at the other end T2 of the body portion 21 is ta2, an arbitrary distance from one end T1 to the other end T2 is x (mm), and the outer diameter of the body portion 21 at the distance x is Dx (mm), the thickness tax of the hoop layer 61 at the outer diameter Dx is linearly proportional to the outer diameter Dx.

That is, the thickness tax of the hoop layer 61 at the outer diameter Dx and the outer diameter Dx have a relationship of tax = kDx, and the larger the outer diameter Dx, the larger the thickness tax. Note that the constant k is a positive value and is appropriately selected based on the set specifications such as the size, material, and shape of the high-pressure tank 10 according to the embodiment, as well as data such as experimental values.

When winding the reinforcing fiber F with a filament winding device, if the rotation speed (rpm) of the liner 11 is constant, the hoop layer 61 can be formed to satisfy tax = kDx by the following method. That is, by making the axial position movement speed (mm/s) of the delivery end OT shown in Figure 5 (a) in the Aikuchi AK that supplies the reinforcing fiber F such as carbon fiber reinforced plastic faster on the small diameter side and slower on the large diameter side, the hoop layer 61 on the large diameter side can be formed thicker to satisfy tax = kDx.

Helical winding is a method of winding reinforcing fibers F to obtain axial strength, and is a winding method that covers the entire liner 11, wrapping the hoop layer 61 formed on the body portion 21 and the outer surfaces of the first dome portion 22 and the second dome portion 23. The helical layer 62 formed by helical winding provides mechanical strength against the stress σz (MPa) that occurs in the axial direction of the liner 11 due to the internal pressure P (MPa) acting on the body portion 21 of the high-pressure tank 10.

As shown in FIG. 5(b), the reinforcing fiber F is wound around the hoop layer 61 and the outer surfaces of the first dome portion 22 and the second dome portion 23 at a winding angle greater than 0° and less than 90° with respect to the central axis L of the liner 11, forming a helical layer 62. Since the body portion 21 of the liner 11 has a tapered shape, with the second dome portion 23 having a larger diameter than the first dome portion 22, the thickness of the helical layer 62 is formed to gradually increase as it moves toward the smaller diameter side along the axial direction. In other words, as shown in FIG. 2, the helical layer 62 is formed with a thickness tb1 at one end T1 of the body portion 21 and a thickness tb2 thicker than the thickness tb1 at the other end T2 of the body portion 21. The reinforcing fiber F forming the helical layer 62 may be made of a fiber or impregnated resin different from that of the hoop layer 61.

Helical winding is a winding method in which the reinforcing fiber F is wound in sequence around the entire circumference of the liner 11, so to speak, in a single stroke, and the number of winding turns is the same on the large diameter side and the small diameter side. The more the number of winding turns in helical winding, the higher the mechanical strength. In the case of a liner 11 having a small diameter first dome portion 22 and a large diameter second dome portion 23, the number of winding turns is determined based on the large diameter side of the liner 11, that is, so as to ensure the mechanical strength of the large diameter side of the liner 11. Therefore, the thickness on the small diameter side is greater than the necessary strength, and as shown in FIG. 2, the thickness of the helical layer 62 of the small area first dome portion 22 is thicker than the thickness of the helical layer 62 of the large area second dome portion 23. As a result, the first dome portion 22 has excess strength higher than the mechanical strength of the second dome portion 23. In order to utilize this excess strength, in this embodiment, the mouthpiece 12 is installed on the small diameter first dome portion 22.

The component force of the internal pressure P acting on the periphery of the inner wall of the through hole of the helical layer 62 through which the shank 41 of the nozzle 12 penetrates, the so-called flange donut area, is transmitted from the inner wall of the through hole to the helical layer 62. This component force of the internal pressure P acts additively in addition to the force of the internal pressure P acting on the helical layer 62, so the helical layer 62 abutting the flange donut area is required to have a higher mechanical strength than other areas other than the flange donut area. In other words, the helical layer 62 in the flange donut area is easily deformed and stress concentration occurs, so the helical layer 62 around the shank 41 of the nozzle 12 is required to have a higher mechanical strength. The nozzle 12 is installed on the first dome section 22, which has a higher mechanical strength of the helical layer 62 than the second dome section and has excess strength.

The component force of the internal pressure P acting on the flange donut area of the nozzle 12 around the inner wall of the through hole of the helical layer 62 through which the shaft portion 51 of the end boss 13 penetrates is transmitted from the inner wall of the through hole to the helical layer 62, similar to the flange donut area of the nozzle 12. Similar to the flange donut area of the nozzle 12, this component force of the internal pressure P acts additionally on top of the force that the internal pressure P exerts on the reinforcing layer 14, but the smaller the diameter of the through hole penetrating the helical layer 62, the smaller the component force becomes.

Therefore, even if the mechanical strength of the second dome section 23 is smaller than that of the first dome section 22, the diameter D2 of the shaft section 51 of the end boss 13 is smaller than the diameter D1 of the shaft section 41 of the base 12, so the component force of the internal pressure P acting on the flange donut area of the end boss 13 is also smaller. As a result, the mechanical strength required for the second dome section 23 is ensured. Note that the area indicated by the dashed line in FIG. 2 indicates the thickness of the helical layer required for strength, but the thickness of the helical layer 62 of the first dome section 22 is formed to be thicker than the thickness of the helical layer required for strength.

The helical winding angle and thicknesses ta1, ta2, tb1, tb2, D1, and D2 are appropriately selected based on the set specifications such as the size, material, and shape of the high-pressure tank 10 according to the embodiment, as well as data such as experimental values.

The effects of the high-pressure tank 10 according to the embodiment will be described.
(1) The high-pressure tank 10 according to the embodiment has a liner 11 and a reinforcing layer 14. The liner 11 has a cylindrical body portion 21 that gradually expands in diameter as it moves along the axial direction, a hemispherical first dome portion 22 that closes the small diameter end of the body portion 21, and a hemispherical second dome portion 23 that closes the large diameter end of the body portion 21. The reinforcing layer 14 has a hoop layer 61 formed by hoop winding reinforcing fiber F, and a helical layer 62 formed by helically winding the reinforcing fiber F. The hoop layer 61 is formed thicker on the second dome portion 23 side than on the first dome portion 22 side.

With this configuration, the high-pressure tank 10 can be installed in the space inside the floor tunnel of a fuel cell vehicle with a rear-wheel drive vehicle structure equipped with an internal combustion engine and a transmission, since the body portion 21 is gradually enlarged in diameter, and the entire space can be effectively utilized. When a so-called oval tank formed with a conventional straight cylindrical body portion is installed in a floor tunnel, the space above the front of the oval tank becomes an empty space. In contrast, the high-pressure tank 10 has an enlarged diameter at the front, so there is no empty space at the front upper space, and more gas can be stored compared to an oval tank. As a result, the cruising distance of the fuel cell vehicle can be extended. In addition, the hoop layer 61 is formed thicker on the second dome portion 23 side than on the first dome portion 22 side, so the mechanical strength of the large diameter side of the body portion 21 can be secured.

(2) In addition, in the high-pressure tank 10 according to the embodiment, the thickness of the hoop layer 61 is formed to be large in proportion to the outer diameter of the body portion 21. This configuration has the effect of ensuring uniform mechanical strength from the small diameter end to the large diameter end of the body portion 21.

(3) In addition, the high-pressure tank 10 has a nozzle 12 that communicates between the inside and outside of the high-pressure tank 10 attached to the first dome portion 22. This configuration ensures the mechanical strength of the nozzle attachment portion 31 of the first dome portion 22 formed by helical winding. That is, helical winding is a winding method in which the reinforced fiber F is wound in a sequential manner as if it were a single stroke, and the number of winding turns is determined to ensure the mechanical strength of the large diameter side, so that the thickness of the helical layer 62 of the first dome portion 22, which has a small area, can be made thicker than the thickness of the helical layer 62 of the second dome portion 23, which has a large area. As a result, the first dome portion 22 can obtain a mechanical strength higher than that of the second dome portion 23. Since the nozzle 12 is attached to the first dome portion 22, which has a high mechanical strength reinforced by the reinforcing layer 14, the function of the nozzle 12, which is to open or close the gas supply path when a valve is attached, can be effectively performed.

(4) In the high-pressure tank 10 according to the embodiment, the nozzle 12 has a shaft portion 41 that penetrates the reinforcing layer 14, and a flange portion 42 that expands in diameter from the shaft portion 41 and abuts against the outer wall surface of the first dome portion 22. With this configuration, the nozzle 12 can be attached in close contact with the outer wall surface of the first dome portion 22 via the flange portion 42, and a valve that opens or closes the gas flow path can be attached to the shaft portion 41.

(5) In the high-pressure tank 10 according to the embodiment, the end boss 13 having a diameter D2 smaller than the shaft portion 41 of the nozzle 12 is attached to the second dome portion 23. This configuration results in ensuring the mechanical strength of the second dome portion 23. That is, the end boss 13 only has the function of chucking one end of the liner 11 when the liner 11 is set in the filament winding device, and the end boss 13 is not required to have high mechanical strength compared to the nozzle 12 to which a valve is attached. In addition, the shaft portion 51 does not need to have a function of circulating gas, and there is no need to attach the end boss 13 to the second dome portion 23 by penetrating the liner 11, so the diameter D1 of the shaft portion 51 may be relatively small. By making the shaft portion 51 of the end boss 13 have a diameter D2 smaller than the diameter D1 of the shaft portion 41 of the base 12, the load imposed by the end boss 13 on the reinforcing layer 14 of the second dome portion 23 is reduced, and the end boss 13 can be attached to the second dome portion 23, which has a lower mechanical strength than the first dome portion 22.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-mentioned embodiments, and various design changes can be made without departing from the spirit of the present invention as described in the claims.

10: High pressure tank, 11: Liner, 12: Cap, 13: End boss, 14: Reinforcement layer, 21: Body, 22: First dome, 23: Second dome, 31: Cap mounting part, 32, 43: Through hole, 33: End boss mounting part, 41, 51: Shaft, 42, 52: Flange, 61: Hoop layer, 62: Helical layer, D1: Diameter of cap shaft, D2: Diameter of end boss shaft, F: Reinforcement fiber

Claims (5)

A high-pressure tank having a liner and a reinforcing layer formed on an outer surface of the liner,
The liner has a cylindrical body portion that gradually expands in diameter along an axial direction, a hemispherical first dome portion that closes a small diameter end of the body portion, and a hemispherical second dome portion that closes a large diameter end of the body portion,
The high-pressure tank is characterized in that the reinforcing layer has a hoop layer formed by hoop-winding reinforcing fibers and a helical layer formed by helically winding the reinforcing fibers, and the hoop layer is thicker on the second dome portion side than on the first dome portion side. The high-pressure tank according to claim 1, characterized in that the thickness of the hoop layer increases in proportion to the outer diameter of the body portion. The high-pressure tank according to claim 1, characterized in that a cap that connects the inside and outside of the high-pressure tank is attached to the first dome portion. The high-pressure tank according to claim 3, characterized in that the cap has a shaft portion that penetrates the reinforcing layer and a flange portion that expands in diameter from the shaft portion and abuts against the outer wall surface of the first dome portion. The high-pressure tank according to claim 4, characterized in that an end boss having a diameter smaller than the shaft portion of the nozzle is attached to the second dome portion.

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