JP2023111622A - Method for manufacturing honeycomb structure cell tank, and honeycomb structure cell tank - Google Patents

Abstract

To improve adhesion between a metal internal tank and its external carbon fiber prepreg.SOLUTION: A low-magnification thermal foaming resin and a carbon fiber prepreg are wound around an outer peripheral surface of a metal thin plate tank, a thermal foaming resin having an inner peripheral circle and an outer peripheral hexagonal face is wound around the tank, the tank is equipped with a hexagonal carbon fiber composite, and the tank is heated up to a temperature at which the carbon fiber prepreg is thermally cured.SELECTED DRAWING: Figure 6

Description

The present invention relates to a high-pressure hydrogen tank using a metal tank for the internal tank, and a manufacturing method thereof.

The weight of 1000 (liters) of liquid hydrogen at atmospheric pressure is 70.8 (Kg). The weight of 1000 (liters) of hydrogen gas at normal temperature and atmospheric pressure is 0.0899 (Kg). 1000 (liters) of hydrogen gas at normal temperature and atmospheric pressure is compressed to 1.25 (liters) at normal temperature and 800 atmospheres. Therefore, the weight of hydrogen at room temperature and atmospheric pressure of 1000 (liters) and the weight of hydrogen at room temperature and atmospheric pressure of 1.25 (liters) at 800 atmospheres are both 0.0899 (Kg). In order to compare with the weight of liquid hydrogen, it is necessary to convert hydrogen gas at room temperature and 800 atm to 1000 (liters).

1.25 (liters) of high-pressure hydrogen gas at room temperature and 800 atmospheres is multiplied by 800 to 1000 (liters). Therefore, the weight of 1000 (liters) of high-pressure hydrogen gas at room temperature and 800 atmospheres is 800 times 0.0899 (Kg), that is, 71.92 (Kg). The weight of liquid hydrogen (atmospheric pressure, -253 degrees) is 70.8 (Kg).

Therefore, high-pressure hydrogen gas (71.92 Kg/1000 l) compressed to 800 atmospheres has a higher density than liquid hydrogen (70.8 Kg/1000 l). When transporting hydrogen in a tank of the same size, it can be seen that high-pressure gas can transport more hydrogen than liquid hydrogen. Therefore, a high-pressure hydrogen tank is more useful than a liquid hydrogen tank in that it can transport more hydrogen.

Patent Document 1, "Honeycomb Structure with Honeycomb Core Arranged in Parallel to Panel Surface and Method for Manufacturing the Same" discloses a method for manufacturing a large-capacity high-pressure gas tank using a honeycomb structure. In addition, Patent Literature 2 and Patent Literature 3 disclose a method of manufacturing a honeycomb structure high-pressure tank using a metal cylindrical thin plate tank and a thermally foamable resin for the inner tank. The structural strength of the high-pressure tanks manufactured by these disclosed patented technologies has been evaluated and verified by a water pressure test with a pressure resistance of 100 MPa. However, all the problems required for high-pressure hydrogen tanks have not been solved by the above-mentioned patented technology. The issues required for high-pressure hydrogen gas tanks are as follows.
(1) It must have structural strength (withstanding pressure) of 70 MPa or more in normal use.
(2) Hydrogen gas sealed at high pressure should not leak from the tank wall surface.
(3) Fatigue fracture due to hydrogen embrittlement should not occur.

Patent No. 6160876 US 10,364,942 B2 US 10,864,684 B2

If the internal tank of the high-pressure gas tank is made of a thin metal plate, the problem of permeation of hydrogen gas through the wall can be solved. However, since hydrogen embrittlement is a phenomenon in which hydrogen molecules penetrate into gaps between metal molecules, there is no mechanical method for overcoming hydrogen embrittlement. In addition, when the inner tank is manufactured from a metal thin plate, there arises a problem that the carbon fiber composite material (CFRP) is peeled off from the metal inner tank.

The peeling problem is that when the internal pressure of the high-pressure gas tank reaches 30 to 40 MPa, the carbon fiber composite material (CFRP) peels from the metal internal tank. A detailed description of this peeling problem is as follows.
(1) When pressure is applied to the high-pressure gas tank, the metal internal tank expands.
(2) This expansion pressure is transmitted to the carbon fiber composite material that is the reinforcement member of the internal tank.
(3) A circumferential stress (hoop stress) is generated in the carbon fiber composite material against the expansion pressure.
(4) Hoop stress causes strain in carbon fiber composites.
(5) The carbon fiber composite material (CFRP) is peeled off due to the strain deviation generated between the metal internal tank and the carbon fiber composite material at ultrahigh pressure.
(6) However, the expansion deformation of the metal internal tank comes into contact with the inner wall of the carbon fiber composite material and stops.
(7) All the internal pressure of the high-pressure tank is borne by the carbon fiber composite material.
(8) Therefore, the strain of the internal tank is smaller than that of the carbon fiber composite.
Many attempts have been made to overcome this problem by improving the adhesive, but all have failed due to the inability to overcome the strain mismatch that occurs between the metal internal tank and the carbon fiber composite.

After improving the adhesive, I came up with the idea that if I sealed some kind of liquid between the metal internal tank and the carbon fiber composite material, I would be able to overcome the misalignment caused by the distortion that occurs between the internal tank and the carbon fiber composite material. There was no way to mechanically seal the liquid.

But the idea that sealing some kind of fluid between the internal tank and the reinforcing carbon-fiber composite to overcome the strain misalignment seems more realistic than improving the adhesive. In addition, if the metal inner tank and the carbon fiber composite material can be separated by an incompressible liquid, ``stress will not occur on the wall of the thin plate tank, which receives the same amount of pressure on the inside and outside of the tank.'' From the theory of mechanical engineering, it is possible to overcome fatigue fracture due to hydrogen embrittlement, which is a difficult problem of high-pressure hydrogen tanks. However, there was simply no means of sealing the liquid between the inner tank and the carbon fiber composite.

Therefore, we decided to wrap the inner tank with a rubber material cut to fit the three-dimensional shape of the cylindrical inner tank instead of the liquid. However, it was impossible to completely fill the gap between the cylindrical internal tank and the carbon fiber composite material with the cut and pasted rubber material.

However, if the gap between the cylindrical inner tank and the carbon fiber composite material can be completely filled with an incompressible material, stress will be generated on the wall surface of the thin plate tank, which receives the same amount of pressure on the inside and outside of the tank. Based on the theory of mechanical engineering that says, "No, it does not", it is thought that fatigue fracture due to hydrogen embrittlement, which is a difficult problem for high-pressure hydrogen tanks, can be overcome. In addition, if the inner tank is made of metal, hydrogen gas will not leak from the wall. These advantages are attractive.

A liquid can (theoretically) completely fill the gap between the three-dimensional shape of the internal tank and the reinforcing carbon fiber composite material, but this is not possible in practice. A solid rubber material has discontinuous gaps somewhere, and it is difficult to confirm where and how many gaps are formed. In practice, internal pressure acting on a high-pressure tank deforms (expands) the metal internal tank and simultaneously deforms the reinforcing carbon fiber composite material, so ideally the deformation of the internal tank is greater than that of the incompressible liquid. A somewhat elastic body that automatically fills the gap between the inner tank and the carbon fiber composite as needed is desirable. If these problems can be overcome, the problem of fatigue fracture due to hydrogen embrittlement and wall permeation of hydrogen gas can be solved.

In order to solve the above problems, in the present invention, the internal tank is evenly wrapped with a thermally foamable resin whose expansion ratio is kept low and which is cut to match the shape of the cylindrical internal tank. When the thermally foamable resin is produced from a thermoplastic resin, the thermoplastic resin is solid at room temperature, so that it can be processed precisely by machining.

As a result, it is possible to minimize the gap between the three-dimensional cylindrical inner tank and the thermally foamable resin. In addition, by manufacturing the thermally foamable resin with a thermoplastic resin, the thermally foamable resin expands in the heating process of the carbon fiber composite material, and at the same time, the cut and pasted resin melts and integrates with the surrounding thermally foamable resin. . In this way the gap between the cylindrical inner tank and the carbon fiber composite can be completely filled.

Specifically, the present invention relates to a honeycomb structure cell tank composed of a metal thin plate tank, a low-ratio thermally foamable resin, a carbon fiber prepreg, a hexagonal thermally foamable resin, and a hexagonal carbon fiber composite. did.

The thermally foamable resin is produced by kneading a thermally foaming agent into a thermoplastic resin such as polypropylene. Thermally foamable resins are solid at room temperature and can be precision machined. When the carbon fiber prepreg is heated to a thermosetting temperature, it melts and becomes fluid, and at the same time, it expands due to thermal foaming.

Hydrogen gas does not leak from the walls of the metal internal tank. The metal internal tank is also used as a pressurizing device for pressurizing the carbon fiber prepreg that reinforces the internal tank from the inside. The wall thickness of the metal sheet tank is 1/100 or less of the internal tank diameter.

Since the low-ratio thermal foaming resin hardly deforms against the compressive force, the expansion force generated in the metal thin plate tank by the high-pressure gas is directly transmitted to the carbon fiber prepreg after thermosetting. As a result, the stress (strain deformation) generated in the thin metal plate tank is extremely small. By interposing a low-ratio thermal foaming resin between the metal thin plate tank and the carbon fiber prepreg, the stress generated in the metal thin plate tank is extremely small, and fatigue fracture due to hydrogen embrittlement, which is a problem of high-pressure hydrogen tanks, is eliminated. resolved.

A metal internal tank does not have the strength to withstand the internal pressure of the high pressure gas. Structural strength against the internal pressure of the high-pressure gas tank is guaranteed only with carbon fiber prepreg.

The honeycomb structure hexagonal cell tank before heat curing contains many air bubbles between the fibers of the carbon fiber prepreg and between the layers of the carbon fiber prepreg wound many times. If these air bubbles remain after thermosetting, the structural strength of the carbon fiber composite material is greatly impaired.

The carbon fiber prepreg in the honeycomb structure hexagonal cell tank after thermosetting is pressurized from the inside of the carbon fiber prepreg by the expansion pressure due to the air pressure of the metal inner tank and the expansion pressure due to the low magnification thermal foaming resin. It is a carbon fiber composite material in which air bubbles are completely eliminated by being pressurized from the outside by the expansion pressure of the square heat-foamable resin and the mechanical reaction force of the outer formwork.

The manufacturing process guarantees the strength structure of the carbon fiber composite produced by the manufacturing process of firmly pressing from both sides of the carbon fiber prepreg.
Hexagonal thermal foaming resin, which is manufactured from high-ratio thermoplastic foaming resin, acts as a highly elastic cushioning material. Protect against shock loads.

A hexagonal carbon fiber composite material before heat curing has many air bubbles between fibers and between layers of the carbon fiber composite material manufactured by stacking many layers. These air bubbles are eliminated by being pressurized from both sides by the expansion pressure of the hexagonal heat-foamable resin from the inside and the mechanical reaction force of the steel outer frame from the outside. Thus, the structural strength of the carbon fiber composite material produced from the hexagonal carbon fiber composite material firmly pressed from both sides is guaranteed by the manufacturing process.

After heat curing, the hexagonal carbon fiber composite material becomes a shell structure of a honeycomb structure to protect the high-pressure tank from external impact loads such as dropping accidents.
The problems to be solved by the present invention are the wall permeation problem of hydrogen gas and fatigue fracture due to hydrogen embrittlement, which are problems of high-pressure hydrogen tanks. Methods to solve these problems are applicable to all high pressure gas tanks.

It is a conceptual diagram of a metal internal tank. FIG. 4 is a conceptual diagram of a metal internal tank wrapped in a low-magnification thermally foamable resin. 1 is a conceptual diagram of an internal tank assembly reinforced with carbon fiber prepreg; FIG. It is a manufacturing process of the honeycomb structure hexagonal cell tank before thermosetting and its conceptual diagram. FIG. 4 is a conceptual diagram of a process of setting the honeycomb structure hexagonal cell tank before heat curing to the outer mold. FIG. 4 is a conceptual diagram of the expansion force generated in the honeycomb structure hexagonal cell tank and the thermally foamable resin during thermosetting. FIG. 2 is a conceptual diagram of a honeycomb structure hexagonal cell tank after thermosetting.

Embodiments for implementing the invention are described below in conjunction with the drawings described above. A high-pressure hydrogen tank using a metal internal tank, a low-ratio thermal foaming resin, and a carbon fiber composite material for reinforcing the internal tank according to the present invention, and a method of manufacturing the same will be described below with reference to the drawings. At the same time, a high-pressure honeycomb structure high-pressure tank made of high-magnification hexagonal thermal foaming resin and hexagonal carbon fiber composite material that can withstand external impact loads such as dropping, and a method of manufacturing the same will be described. A high-pressure hydrogen tank that can prevent permeation of hydrogen gas through the wall surface and fatigue fracture due to hydrogen embrittlement and a manufacturing method of a honeycomb structure high-pressure tank that can withstand external impact loads are closely related.

FIG. 1 shows a conceptual diagram of a metal internal tank 1 . A metal internal tank 1 is composed of a thin metal plate tank 2 and connection ports 3 provided on both sides of the tank 2 . The metal thin plate tank 2 is made of a metal such as SUS316 that is resistant to hydrogen embrittlement. The connection port 3 is made of metal and fixed to the metal thin plate tank 2 by welding or silver brazing. The metal internal tank 1 is not a structural strength member to withstand the internal pressure of the high pressure gas tank. However, since the metal internal tank 1 is made of metal, the hydrogen gas does not leak from the wall surface of the internal tank. As will be described in detail later with reference to the drawings, the metal internal tank 1 is also used as a pressurizing device for pressurizing the carbon fiber prepreg that reinforces the internal tank from the inside. Therefore, it is desirable that the wall thickness of the thin metal plate tank 2 is not too thick. The wall thickness of the metal thin plate tank 2 is preferably 1/100 to 2/100 or less of the diameter of the metal inner tank 1 . Moreover, it is desirable to consider the influence of hydrogen embrittlement when selecting the wall thickness. The internal tank used in the prototype tank that cleared the pressure resistance of 100 MPa is made of SUS316 and has a diameter of 80 mm and a wall thickness of 0.8 mm. The pressurization pressure for pressurizing the carbon fiber prepreg from the inside is preferably 100 to 200 atmospheres.

FIG. 2 shows a conceptual diagram of a figure in which a metal internal tank 1 is uniformly wrapped with a low-magnification thermal foaming resin 4 . The inner tank 1 made of metal shown in FIG. The low magnification thermal foaming resin 4 is made of a material in which a thermal foaming agent is kneaded into a thermoplastic resin such as polypropylene. The low-magnification thermally foamable resin 4 is solid at room temperature and can be precision machined. When the thermally foamable resin 4 is heated to a temperature at which the carbon fiber prepreg is thermally cured, it melts and becomes fluid, and at the same time thermally foams and expands. The plasticizing temperature and thermal foaming temperature of the thermal foaming resin used in the prototype tank are 120°C to 150°C. This temperature depends on the properties of the thermoplastic resin and the thermal blowing agent.

The low-ratio thermal foaming resin 4 is processed so as to wrap the metal inner tank 1 with a uniform thickness, and as shown in the right half of FIG. ing. In the heating process, the thermally foamable resin 4 made of thermoplastic resin melts and integrates with the surrounding thermally foamable resin. At the same time, the low-magnification thermal foaming resin 4 is thermally foamed to completely fill the mechanical gap between the metal inner tank 1 and the low-magnification thermal foaming resin 4 . When the thermal foaming resin returns to room temperature after being thermally foamed, it hardens while maintaining the foamed shape. At that time, the thermal foaming resin 4 has a certain degree of elasticity depending on the expansion rate. As a result, when the manufacturing process of the high-pressure tank is finished and the high-pressure gas is actually filled, the low-magnification thermal foaming resin 4 absorbs the deformation of the metal inner tank 1 caused by the high-pressure gas and is slightly deformed. However, excessive elasticity causes distortion (stress fatigue) of the metal internal tank 1 .

The following two functions are required for the low-magnification thermal foaming resin 4 .
(1) Completely fill the mechanical gap between the internal tank and the carbon fiber composite material.
(2) The expansion pressure of the internal tank due to high-pressure gas is directly transmitted to the carbon fiber composite material.
Therefore, the foaming ratio of the thermally expandable resin 4 having a low expansion ratio is preferably about 2 to 3 times. A heating process for the carbon fiber composite material will be described later with reference to the drawings.

FIG. 3 shows a conceptual diagram of an internal tank assembly 6 reinforced with carbon fiber prepreg. The internal tank assembly 6 is obtained by wrapping the metal internal tank 1 shown in FIG. 1 with the low-ratio thermal foaming resin 4 shown in FIG. Both thermoplastic and thermosetting adhesives can be used for the carbon fiber prepreg 5 . Here, a general thermosetting carbon fiber prepreg will be explained.

The metal internal tank 1 does not have the strength to withstand the internal pressure of the high pressure gas. The internal pressure of the high-pressure gas tank is handled only by the carbon fiber prepreg 5. Therefore, it is important to ensure the structural strength of the carbon fiber prepreg 5 in the manufacturing process.

The internal tank assembly 6 before being thermally cured contains many air bubbles between the fibers of the carbon fiber prepreg 5 and between the layers of the carbon fiber prepreg 5 wound many times. If these air bubbles remain after thermosetting, the structural strength of the carbon fiber composite material is greatly impaired. Therefore, it is necessary to completely remove these air bubbles in the step of thermally curing the carbon fiber prepreg 5 . A mechanical gap exists between the metal internal tank 1 and the low-magnification thermal foaming resin 4 . If this gap is left as it is, it becomes a cause of impairing the fatigue strength of the high-pressure tank. In particular, the mechanical gap between the metal internal tank 1 and the low-magnification thermal foaming resin 4 in the high-pressure hydrogen tank causes the fatigue strength of the metal internal tank 1 to decrease.

Carbon fiber prepregs are available in various thicknesses, weights, strengths, curing temperatures, and adhesive contents depending on the application. The carbon fiber prepreg used in the prototype tank that cleared the pressure resistance of 100 MPa has a thickness of 0.1 mm, a curing temperature of 130° C., and a lamination thickness of 5.0 mm. Sufficient knowledge is required for the selection of carbon fiber prepreg and thermally foamed resin, the method of winding reinforcement with carbon fiber prepreg, and the like.

FIGS. 4(A) to 4(E) show conceptual diagrams of the honeycomb structure hexagonal cell tank 9 before heat curing and its manufacturing process. FIG. 4A shows the internal tank assembly 6. FIG. FIG. 4(B) shows a view of attaching two split hexagonal thermally foamable resins 7 which are the basic elements of the honeycomb structure to the internal tank assembly 6 . FIG. 4(C) shows a view of integrating the internal tank assembly 6 and the hexagonal thermal foaming resin 7 . FIG. 4(D) shows a diagram of attaching a hexagonal carbon fiber composite material 8 divided into two or more pieces to a hexagonal thermally foamable resin 7 . FIG. 4(E) shows a view of manufacturing a hexagonal cell tank 9 with a honeycomb structure by integrating a hexagonal thermal foaming resin 7 and a hexagonal carbon fiber composite material 8 .

A honeycomb structure hexagonal cell tank 9 is composed of an inner tank assembly 6 , a hexagonal thermal foaming resin 7 and a hexagonal carbon fiber composite material 8 . The internal tank assembly 6 is identical to the internal tank assembly 6 shown in FIG. The hexagonal heat-foamable resin 7 is made of a material in which a heat-foaming agent is kneaded into a thermoplastic resin, like the low-magnification heat-foamable resin 4 shown in FIG. The mechanical properties at room temperature before thermal foaming are the same as those of the thermally foamable resin 4 with a low expansion ratio. However, the hexagonal thermally expandable resin 7 has a larger expansion ratio than the thermally expandable resin 4 with a lower expansion ratio.

The hexagonal thermally foamable resin 7 has a hexagonal honeycomb cell shape, which is a constituent element of the honeycomb structure, and is molded so as to accommodate the internal tank assembly 6 therein. It is preferable that it is divided into two or more in consideration of workability. The hexagonal heat-foamable resin 7 is fundamentally different from the low-magnification heat-foamable resin 4 shown in FIG. The following three functions are required for the hexagonal thermal foamable resin 7 .
(1) In the step of heating and curing the carbon fiber prepreg 5 that reinforces the metal internal tank 1, the carbon fiber prepreg 5 is pressurized from the outside.
(2) In the step of heating and curing the hexagonal carbon fiber composite material 8 forming the shell structure of the honeycomb structure, the hexagonal carbon fiber composite material 8 is pressurized from the inside.
(3) When an external impact load such as a drop acts on the high-pressure tank of honeycomb structure, the hexagonal thermal foaming resin 7 absorbs the external impact load together with the hexagonal carbon fiber composite material 8 .
Therefore, the expansion ratio of the hexagonal thermally expandable resin 7 is preferably 5 to 10 times larger than that of the thermally expandable resin 4 with a low expansion ratio.

The hexagonal carbon fiber composite material 8 is made of carbon fiber prepreg and is made to cover or wrap the hexagonal thermal foamable resin 7 . It is preferable that it is divided into two or more in consideration of workability. The hexagonal carbon fiber composite material 8 can be made of thermosetting carbon fiber prepreg or thermoplastic carbon fiber prepreg, but is preferably made of thermoplastic carbon fiber prepreg. The reason is that the thermosetting prepreg is sticky at room temperature, so when a plurality of honeycomb structure hexagonal cell tanks 9 are combined to form a honeycomb structure, the metal internal tank 1 built into the honeycomb structure hexagonal cell tank 9 is This is because the piping work becomes difficult.

FIG. 5 is a conceptual diagram of the process of setting the honeycomb structure hexagonal cell tank 9 before heat curing to the outer formwork 10 . The concept of the process of setting the honeycomb structure hexagonal cell tank 9 before thermosetting to the outer formwork 10 is the metal thin plate tank 2, the low magnification thermal foaming resin 4, the carbon fiber prepreg 5, the hexagonal thermal foaming resin 7, A hexagonal carbon fiber composite 8 , an outer formwork 10 , outer formwork reinforcing members 11 , bolts 12 and nuts 13 are illustrated. The outer formwork 10, the reinforcing member 11 of the outer formwork, the bolt 12, and the nut 13 are made of steel, and each has a strong structural strength. The reinforcing member 11 of the outer formwork is preferably fixed to the outer formwork 10 by spot welding or the like.

The process shown in FIG. 5 is a work of setting the honeycomb structure hexagonal cell tank 9 before heat curing shown in FIG. In the case of a single tank, the work itself is simple, but the process involves various problems. The challenges are as follows.
(1) A mechanical gap exists between the thin metal plate tank 2 and the low-magnification thermal foaming resin 4 in FIG. This mechanical gap causes fatigue failure of the metal thin plate tank 2 due to repeated loading of high-pressure gas filling. No mechanical gap, no matter how small, is allowed in the high-pressure gas tank.
(2) In FIG. 5, there is a mechanical gap between the thermally foamable resin 4 of low magnification and the carbon fiber prepreg 5 before being thermally cured. No mechanical gap, no matter how small, is allowed in the high-pressure gas tank.
(3) The carbon fiber prepreg 5 before heat curing contains many air bubbles between the fibers and between the layers of the carbon fiber prepreg 5 wound many times. These air bubbles impair the strength of the carbon fiber composite material after heat curing and must be removed during the heat curing process.
(4) In FIG. 5, there is a mechanical gap between the carbon fiber prepreg 5 and the hexagonal thermal foamable resin 7 before being thermally cured. No mechanical gap, no matter how small, is allowed in the high-pressure gas tank.
(5) A mechanical gap exists between the hexagonal thermal foamable resin 7 and the hexagonal carbon fiber composite material 8 before being thermally foamed in FIG. No mechanical gap, no matter how small, is allowed in the high-pressure gas tank.
(6) In FIG. 5, there is a mechanical gap between the hexagonal carbon fiber composite material 8 and the steel outer frame 10 before heat curing. If this mechanical gap is not completely filled, no mechanical reaction force is generated in the outer formwork 10 .
(7) The hexagonal carbon fiber composite material 8 before being cured by heating and pressure contains many air bubbles between the fibers and between the layers of the hexagonal carbon fiber composite material 8 manufactured by stacking many layers. I'm in. These air bubbles impair the strength of the carbon fiber composite material after heat curing and must be removed during the heat curing process.

FIG. 6 is a conceptual diagram of the expansion force generated in the honeycomb structure hexagonal cell tank 9 and the thermally foamable resin during thermosetting and the mechanical reaction force due to the outer formwork. The concept of the expansion force generated in the honeycomb structure hexagonal cell tank 9 and the thermal foaming resin during thermosetting and the mechanical reaction force due to the outer formwork is the metal thin plate tank 2, the low magnification thermal foaming resin 4, and the carbon fiber prepreg. 5, hexagonal thermal foaming resin 7, hexagonal carbon fiber composite material 8, outer frame 10, outer frame reinforcing member 11, bolt 12, nut 13, pneumatic expansion pressure 14, low magnification thermal foaming resin expansion pressure 15 by 4, expansion pressure 16 by hexagonal thermal foaming resin 7, and mechanical reaction force 17 of the outer mold. The expansion pressure 14 due to air pressure is the expansion force generated when the internal tank is filled with high-pressure air from the outside and the metal thin plate tank 2 is expanded. The expansion pressure 15 by the low-magnification thermally foamable resin 4 is the expansion force generated in the low-magnification thermally foamable resin 4 heated to a high temperature when the carbon fiber prepreg 5 is thermally cured. The expansion pressure 16 by the hexagonal thermal foaming resin 7 is the expansion force generated in the hexagonal thermal foaming resin 7 heated to a high temperature when the carbon fiber prepreg 5 is thermally cured. The mechanical reaction force 17 of the outer formwork is the sum of the expansion pressure 14 due to the air pressure, the expansion pressure 15 due to the low-magnification thermal foaming resin 4 and the expansion pressure 16 due to the hexagonal thermal foaming resin 7 . Therefore, the outer formwork 10, the reinforcing member 11 of the outer formwork, the bolt 12, and the nut 13 must be made of steel so that their rigidity and structural strength are sufficiently enhanced. Although not shown in the figure, an atmospheric pressure heating oven can be used as the heating furnace for heating the honeycomb structure hexagonal cell tank 9 fixed to the outer mold. Desirably, the heating time is 2.0 to 3.0 hours, and the cooling time after heating is 12 hours or more.

The expansive force shown in FIG. 6 solves all the problems of FIG. The reason is as follows.
(1) The mechanical gap that exists between the metal thin plate tank 2 before heat curing and the low-magnification thermal foaming resin 4 is the expansion pressure 14 due to the air pressure of the metal thin-plate tank 2 and the low-magnification thermal foaming resin 4. It is completely filled with the expansion pressure 15 by the resin 4 and the low magnification thermally expandable resin 4 which is heated to a high temperature to fluidize and expand.
(2) The mechanical gap that exists between the low-ratio thermally foamable resin 4 and the carbon fiber prepreg 5 before heat curing is caused by the expansion pressure 14 due to the air pressure, the expansion pressure 15 due to the low-ratio thermally foamable resin 4, and the high temperature. It is completely filled with a low magnification thermally foamable resin 4 that is heated to fluidize and expand.
(3) The air bubbles existing between the fibers of the carbon fiber prepreg 5 and between the layers of the carbon fiber prepreg 5 wound many times are lower than the expansion pressure 14 by the air pressure that pressurizes the carbon fiber prepreg 5 from the inside. The expansion pressure 15 by the thermal foaming resin 4 of the magnification and the expansion pressure 16 by the pressurized hexagonal thermal foaming resin 7 from the outside of the carbon fiber prepreg 5 are removed.
(4) The mechanical gaps existing between the carbon fiber prepreg 5 before heat curing and the hexagonal heat-foamable resin 7 are fluidized and expanded by being heated to a high temperature with the expansion pressure 16 by the hexagonal heat-foamable resin 7. It is completely filled with a hexagonal thermal foaming resin 7 which
(5) The mechanical gaps existing between the hexagonal thermally foamable resin 7 and the hexagonal carbon fiber composite material 8 before being heated and foamed are filled with the expansion pressure 16 by the hexagonal thermally foamable resin 7 and the high temperature heating and fluidity. It is completely filled with a hexagonal thermal foaming resin 7 that softens and expands.
(6) Before heat curing, the mechanical gap that exists between the hexagonal carbon fiber composite material 8 and the steel outer mold 10 is the expansion pressure 16 due to the hexagonal thermal foaming resin 7 and the steel outer mold. Due to the mechanical reaction force 17 by the formwork 10, the carbon fiber composite material 8 is strongly pressed against the steel outer formwork 10 and disappears.
(7) The hexagonal carbon fiber composite material 8 before being cured by heating and pressure contains many air bubbles between the fibers and between the layers of the hexagonal carbon fiber composite material 8 manufactured by stacking many layers. I'm in. These air bubbles force the hexagonal carbon fiber composite material 8 against the steel outer mold 10 due to the expansion pressure 16 from the hexagonal thermal foamable resin 7 and the mechanical reaction force 17 from the steel outer mold 10. disappear by doing so. In order to ensure the reaction force of the steel outer frame 10, it is preferable to increase the expansion ratio of the hexagonal thermally foamable resin 7. As shown in FIG.

FIG. 7 is a conceptual diagram of the honeycomb structure hexagonal cell tank 18 after heat curing. The honeycomb structure hexagonal cell tank 18 after thermosetting is composed of a metal thin plate tank 2, a low-ratio thermal foaming resin 4, a carbon fiber prepreg 5, a hexagonal thermal foaming resin 7, and a hexagonal carbon fiber composite material 8. . This component is the same as the honeycomb structure hexagonal cell tank 9 before heat curing, but the structural strength of the carbon fiber composite material and the degree of adhesion of each component are completely different from the honeycomb structure hexagonal cell tank 9 before heat setting in FIG.
(1) All the mechanical gaps in the honeycomb structure hexagonal cell tank 9 before heat curing completely disappear in the honeycomb structure hexagonal cell tank 18 after heat curing.
(2) The expansion ratio of the low-expansion thermal foaming resin 4 is as small as 2 to 3 times. In other words, the thermally expandable resin 4 with a low magnification is hardly deformed by the compressive force. Therefore, the expansion pressure generated in the metal thin plate tank 2 by the high pressure gas is directly transmitted to the carbon fiber prepreg 5 after thermosetting. As a result, the stress (strain deformation) generated in the thin metal plate tank 2 is extremely small. In other words, the stress generated in the metal thin plate tank 2 becomes extremely small by interposing the low-ratio thermal foaming resin 4 between the metal thin plate tank 2 and the carbon fiber prepreg 5, which is a problem for high-pressure hydrogen tanks. Fatigue fracture due to hydrogen embrittlement is reduced.
(3) The thin metal plate tank 2 and the carbon fiber prepreg 5 are prevented from coming into direct contact with each other by interposing the thermal foaming resin 4 having a low expansion ratio between the metal thin plate tank 2 and the carbon fiber prepreg 5 . Therefore, the problem that the carbon fiber prepreg 5 after thermosetting is peeled off from the metal thin plate tank 2 is also solved.
(4) The honeycomb structure hexagonal cell tank 9 before heat curing contains many air bubbles between the fibers of the carbon fiber prepreg 5 and between the layers of the carbon fiber prepreg 5 wound many times. If these air bubbles remain after thermosetting, the structural strength of the carbon fiber composite material is greatly impaired. The carbon fiber prepreg 5 of FIG. 7 is pressurized from the inside of the carbon fiber prepreg 5 by the expansion pressure 14 due to the air pressure of the metal internal tank 1 shown in FIG. A carbon fiber composite in which air bubbles are completely eliminated by pressurizing from the outside of the carbon fiber prepreg 5 by the expansion pressure 16 by the high-magnification hexagonal thermal foaming resin 7 and the mechanical reaction force 17 by the outer formwork 10 It is wood. The structural strength of the carbon fiber composite material produced from the carbon fiber prepreg 5 is guaranteed by the manufacturing process in which the carbon fiber prepreg 5 is firmly pressed from both sides.
(5) The hexagonal thermal foaming resin 7 made of high-ratio thermoplastic foaming resin acts as a highly elastic cushioning material to protect the carbon fiber composite material produced from the carbon fiber prepreg 5 from external impact loads such as dropping. Protect.
(6) Many air bubbles exist between the fibers in the hexagonal carbon fiber composite material 8 before heat curing and between the layers of the carbon fiber composite material 8 manufactured by stacking many layers. These air bubbles are pressurized from the inside by the expansion pressure 16 of the hexagonal heat-foamable resin 7 and are eliminated by being pressurized from the outside by the mechanical reaction force 17 of the steel outer frame 10 . In this way, the structural strength of the carbon fiber composite material produced from the hexagonal carbon fiber composite material 8 firmly pressed from both sides is guaranteed by the manufacturing process, and the shell structure of the honeycomb structure will fall. to protect the high pressure tank from external impact loads.

It is conceivable that the shape and purpose of the honeycomb structure high-pressure hydrogen tank of the present invention may be changed in various ways. The spirit of the present invention is the development of a high-pressure hydrogen tank that solves the problems of structural strength, airtightness of high-pressure gas tanks, and fatigue fracture due to hydrogen embrittlement, which are problems of high-pressure hydrogen tanks, by using a metal internal tank and thermal foaming resin. is. In addition, the honeycomb structure of the tank ensures safety against external shock loads such as falling accidents. The invention is applicable to all high pressure gas tanks.

Although the present invention has been fully described in terms of its implementation and accompanying drawings, it should be noted that various changes and modifications will become apparent to those skilled in the art. Such changes and modifications are defined by the appended claims and are included within the scope of the invention.

1... metal inner tank 2... metal thin plate tank 3... connection port 4... low magnification thermal foaming resin 5... carbon fiber prepreg 6... inner tank assembly 7... Hexagonal thermal foaming resin, 8... Hexagonal carbon fiber composite material, 9... Honeycomb structure hexagonal cell tank, 10... Outer frame, 11... Reinforcing member, 12... Bolt, 13... Nut, 14... ...Expansion pressure due to air pressure, 15...Expansion pressure due to low-magnification thermal foaming resin, 16...Expansion pressure due to hexagonal thermal foaming resin, 17...Mechanical reaction force of outer frame, 18...Heat curing Later honeycomb structure hexagonal cell tank.

Claims (13)

A low-ratio thermal foaming resin and a carbon fiber prepreg are sequentially wound around the outer peripheral surface of a thin metal plate tank, a thermal foaming resin having an inner circumference and an outer hexagonal surface is wound, and a hexagonal carbon fiber composite material is attached. and heating the carbon fiber prepreg to a temperature at which the carbon fiber prepreg is thermally cured. 2. The method for manufacturing a honeycomb structure cell tank according to claim 1, wherein the thermal foaming resin is formed by kneading a thermal foaming agent into a thermoplastic resin. 2. The method for manufacturing a honeycomb structure cell tank according to claim 1, wherein the thermofoamable resin contained therein has fluidity when the carbon fiber prepreg is heated. 2. The method for manufacturing a honeycomb structure cell tank according to claim 1, wherein the metal thin plate tank has a wall thickness of 1/100 or less of the inner tank diameter. 2. The method of manufacturing a honeycomb structure cell tank according to claim 1, wherein said thin metal plate tank is made of a metal that prevents hydrogen gas from leaking from the wall surface. 2. The method for manufacturing a honeycomb structure cell tank according to claim 1, wherein high-pressure air is introduced into the metal thin plate tank and pressurized toward the carbon fiber prepreg. After cooling to room temperature, the low-ratio thermal foaming resin fluidized and adhered between the metal thin plate tank and the carbon fiber prepreg directly transmits the expansion force generated in the metal thin plate tank by high pressure gas to the carbon fiber prepreg. The method for manufacturing a honeycomb structure cell tank according to claim 3, characterized in that: It is pressurized from the inside of the carbon fiber prepreg by the expansion pressure due to the air pressure of the metal thin plate tank and the expansion pressure due to the low magnification thermal foaming resin, and the expansion pressure due to the high magnification hexagonal thermal foaming resin and the mechanical 2. The method for manufacturing a honeycomb structure cell tank according to claim 1, wherein internal air bubbles are eliminated by applying pressure from the outside by a reaction force. Hexagonal thermal foaming resin, which is manufactured from high-ratio thermoplastic foaming resin, acts as a highly elastic cushioning material. A method for manufacturing a honeycomb structure cell tank according to claim 1, characterized in that it is protected from impact loads. 2. The method for manufacturing a honeycomb structure cell tank according to claim 1, wherein the hexagonal carbon fiber composite material after thermosetting becomes a shell structure of a honeycomb structure to protect the high pressure tank from an external impact load such as a falling accident. . A low-ratio thermal foaming resin and carbon fiber prepreg are wrapped around the outer surface of a thin metal plate tank, a thermal foaming resin having an inner circle and an outer hexagonal surface is wound, and a hexagonal carbon fiber composite material is attached. A honeycomb structure cell tank characterized by being formed by thermosetting the carbon fiber prepreg. 12. The honeycomb structure cell tank according to claim 11, wherein the wall thickness of the metal thin plate tank is 1/100 or less of the inner tank diameter. 12. The honeycomb structure cell tank according to claim 11, wherein the metal thin plate tank is made of a metal that prevents hydrogen gas from leaking from the wall surface.

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