JP2013108521A - Long high pressure container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high pressure container having a reinforcing fiber layer which absorbs axial differential shrinkage between a metal liner and a carbon fiber layer, and is favorable in improving high-pressure resistance and fatigue resistance.SOLUTION: In a long high pressure container A of a structure in which on an outer circumferential surface of a metal liner 1 having a barrel part 2 and dome parts 3a, 3b and formed so that the total length between dome parts at both ends is 2 m to 6 m, fibers impregnated with a thermoset resin are wound around, a non-conductive fiber layer 11 is formed as an insulation layer on an innermost side contacting the metal liner, and hoop-wound fiber layers 12, 14, 16 of carbon fiber and herically-wound fiber layers 13, 15, 17 of carbon fiber are alternately laminated sequentially at least by three layers on the outside of the insulation layer, forming six layers or more of carbon fiber layers in total, and the insulation layer is formed thinner than any of carbon fiber layers.

Description

  The present invention relates to a long high-pressure vessel in which a reinforcing fiber layer made of resin-impregnated fibers is formed on the outer peripheral surface of a metal liner having an axial length of 2 m or more. The high-pressure container of the present invention is used, for example, for storing and transporting a large amount of high-pressure gas in a gas storage facility or a gas transport vehicle.

Fuel cell vehicles are being developed as next-generation vehicles. Fuel cell vehicles use hydrogen gas as fuel. Hydrogen gas is filled in a vehicle-mounted high-pressure vessel at a gas station, but it is necessary to store a large amount of hydrogen gas at the gas station, and a high-pressure vessel for that purpose is required. In addition, a high-pressure vessel for transporting a large amount of hydrogen gas is also required for a transport vehicle for transporting hydrogen gas to a gas station.
Thus, there is a need for a high-pressure vessel for storing and transporting a large amount of gas.

As a high-pressure gas container that can be reduced in weight, Patent Document 1 discloses an invention related to a high-pressure gas mobile storage module for transporting and using high-pressure gas in an elongated cylindrical container, and a composite material container used therefor. It is disclosed.
According to this document, a high-pressure gas container in which a fiber layer that imparts strength in the axial direction and the circumferential direction is formed on a cylindrical container having a length of at least 10 feet (about 3 m), the cylindrical core ( The first layer (inner layer) and the second layer (outer layer) covering the liner) are axially wound layers (helical winding) made of glass fibers, and are made of carbon fibers between the first layer and the second layer. A high-pressure gas container in which a third layer (intermediate layer) of circumferential winding (hoop winding) is formed is described. In addition, the thickness of any of the three layers is preferably 0.1 inch (0.25 cm) to 0.5 inch (1.3 cm).

Further, according to the above document, when glass fiber and carbon fiber are compared, carbon fiber has higher strength, but glass fiber is considerably cheaper, carbon fiber is conductive, and glass fiber is non-conductive. Since it is conductive, the reinforcing fiber layer is disclosed to have the following structure.
First, by making the inner layer a glass fiber layer, the carbon fiber and the metal core are electrically insulated to ensure axial strength and circumferential strength while eliminating corrosion (electric corrosion).
Further, by using carbon fibers having higher strength than glass fibers in the circumferentially wound intermediate layer, the strength is secured against the load of the circumferential component that is most easily damaged.
In addition, the outer layer is a glass fiber layer to enhance axial strength and protect relatively brittle carbon fibers from contact damage.

Japanese National Patent Publication No. 8-510428

  By the way, even in a high-pressure vessel reinforced by forming a glass fiber reinforcing layer and a carbon fiber reinforcing layer on the outer peripheral surface of a metal liner, in order to be able to store a larger amount of gas, it can withstand higher pressure than before. In addition, there is a need for a pressure vessel that is excellent in fatigue resistance when repeated pressurization and depressurization. Specifically, for example, the burst pressure (high pressure resistance) is 2.25 times or more of the maximum filling pressure. It is required to have fatigue resistance that can withstand at least 11250 cycles under a pressurized condition such as a working pressure (maximum filling pressure) of 35 Pa, 45 MPa, and 80 Pa. Yes.

  To form a high-pressure container that can withstand such harsh conditions, it is sufficient to make the metal liner sufficiently thick, but this increases the weight of the container and increases manufacturing and transportation costs. It is no longer a typical high pressure vessel. Therefore, it is preferable to improve the high pressure resistance and fatigue resistance by improving the reinforcing fiber layer while suppressing the thickness of the metal liner as much as possible.

  As for the reinforcing fiber layer, as disclosed in the above-mentioned patent documents and the like, an insulating layer (resin layer or resin-impregnated glass fiber layer) is formed from the viewpoint of preventing corrosion (electric corrosion), hoop winding and helical winding. Reinforcing the strength in the axial direction and the strength in the circumferential direction, the carbon fiber layer can increase the strength in the circumferential direction rather than the glass fiber layer, and the carbon fiber layer is relatively brittle. It is known that it is preferable to form a resin layer as a protective layer.

  However, the pressure resistance and fatigue resistance of the high-pressure vessel using the glass fiber layer and the carbon fiber layer as the reinforcing fiber layer are further improved, and the thermal expansion difference between the metal liner and the reinforcing fiber layer, which is a problem in the long high-pressure vessel In order to suppress the peeling (described later) due to, almost no study has been made on what kind of reinforcing fiber layer should be used, simply increasing the number of turns (the thickness of the reinforcing fiber layer) or reinforcing fiber Increasing the number of layers only improved the pressure resistance.

Therefore, the present invention is a high-pressure container having a reinforcing fiber layer, while absorbing the axial shrinkage difference between the metal liner and the carbon fiber layer, and improving the high-pressure resistance and fatigue resistance, The purpose of this study is to provide a high-pressure container with a well-balanced and improved durability by examining the winding method and the number of layers.
The present invention also includes a reinforcing fiber layer that is preferable in the case of a high-pressure vessel having a length of 2 m or more, particularly in the axial length of the metal liner (the length between the dome portions extending on both sides of the body portion). The object is to provide a high-pressure vessel.

In general, in a high-pressure container having a reinforcing fiber layer impregnated with a thermosetting resin, when the reinforcing fiber layer is cured at a high temperature by heating and then returned to room temperature in the manufacturing process, the metal liner and the reinforcement are used. Due to the difference in thermal expansion coefficient between the fiber layers, a force directed in the axial direction of the high-pressure vessel acts on the boundary surface between the two. When the total length of the high-pressure vessel is short, this is not a problem, but when the high-pressure vessel is longer than 2 m, the difference in shrinkage due to the difference in thermal expansion coefficient between the metal liner and the reinforcing fiber layer increases (7 mm). As described above, both may be partially separated at the boundary surface.
A high-pressure container in a state where peeling has occurred at the boundary surface is inferior in pressure resistance and fatigue resistance compared to a state where peeling has not occurred. Therefore, the present invention was made by examining the structure of the reinforcing fiber layer that hardly peels off at the interface after thermosetting.

  That is, the present invention made in order to solve the above-mentioned problems has a cylindrical body part and dome parts extending at both ends of the body part, and the total length between the dome parts on both sides is 2 m. A long high-pressure vessel having a structure in which a fiber impregnated with a thermosetting resin is wound around the outer peripheral surface of a metal liner formed to be 6 m or less, and the innermost side in contact with the metal liner is non-conductive. The conductive fiber layer is formed as an insulating layer, and at least three carbon fiber hoop-wrapped fiber layers and carbon fiber helically-wrapped fiber layers are alternately stacked on the outer side of the insulating layer, so that a total of six or more carbon fiber layers are formed. In addition, the insulating layer is formed thinner than any of the carbon fiber layers.

In the present invention, the glass fiber layer is used exclusively as an insulating layer and a heat shrinkage absorbing layer, and is not used as a layer for reinforcing strength. By making it as thin as possible, the ratio of the carbon fiber layer to the glass fiber layer is increased. And on the insulating layer of glass fiber, as a reinforcing fiber layer for securing the circumferential strength and the axial strength, the hoop-wrapped carbon fiber layer and the helical-wrapped carbon fiber layer are alternately divided into at least three layers. Increase the number of boundary surfaces. The boundary between the helical winding layer and the hoop winding layer acts as a relaxation surface that absorbs the force to be peeled off due to the difference in thermal shrinkage, and increasing the number of layers increases the number of interlayers that become relaxation surfaces, and heat between each layer. The contraction is divided and absorbed. This reinforces the compressive strength and fatigue strength with the reinforcing fiber layer and divides the difference in thermal shrinkage between the metal liner and the reinforcing fiber layer between the layers where the helical winding and the hoop winding are alternately formed. And used as a heat-shrinkable absorbing layer.
Accordingly, the thin glass fiber layer that is the innermost layer, and the layers formed by the carbon fiber hoop-wrapped fiber layer and the carbon fiber helically-wrapped fiber layer that are alternately formed on each of the three or more layers. By absorbing the difference in heat shrinkage and further reinforcing the axial strength and circumferential strength of the carbon fiber, a high-pressure container excellent in high-pressure resistance and fatigue resistance can be obtained.

Here, the insulating layer is a non-conductive fiber layer made of a glass fiber layer, and the thickness of the insulating layer is preferably 0.3 mm or more and 0.9 mm or less.
If the thickness of the glass fiber layer of the innermost insulating layer is too thin than 0.3 mm, the heat shrinkage difference may not be sufficiently absorbed. This is clear from the fact that the shear strain ν increases as the layer thickness decreases according to Hooke's law (axial shear strain ν = axial shrinkage ÷ layer thickness). If the thickness is greater than 0.9 mm, there is no problem as an insulating layer, but the effect of reinforcing the liner strength by the carbon fiber layer formed thereon is reduced, and as a result, it is difficult to improve the strength. The fiber layer increases the ratio of the carbon fiber layer and improves the pressure resistance (high pressure resistance, fatigue resistance) by preventing the glass fiber layer from becoming thicker than at least the carbon fiber layer.

Furthermore, the thickness of each carbon fiber layer is preferably 3 mm or more.
The reinforcing strength depends on the thickness of the entire carbon fiber layer (total), but by setting it to 3 mm or more, the carbon fiber layer is sufficiently thicker than the glass fiber layer, and is the innermost layer most affected by the glass fiber layer. The carbon fiber layer can also serve as a reinforcing fiber layer by maintaining a sufficient elastic modulus.

In the present invention, the “dome portion” means that the outer diameter of the tank greatly changes so as to form a curved surface from the body portion of the container to the base portion (or depending on the manufacturing method, one side is the bottom portion). The parts are collectively called. The shape of the curved surface is not particularly limited. Therefore, the “dome portion” includes curved surfaces such as a bowl shape, a semicircular shape, an elliptical shape, and a parabolic shape.
The reason why the “metal liner of 2 m or more” is used is that peeling of the thermosetting resin due to the amount of change in thermal shrinkage that occurs during the manufacturing process is less problematic at 2 m or less.
The reason why the metal liner of 6 m or less is used is that when the length is longer than this, practical problems such as difficulty in handling the container due to size and weight problems occur.

The thermosetting resin impregnated in the fiber layer is preferably an epoxy resin, but is not particularly limited, and may be phenol, urethane, acrylic resin, or the like.
The “non-conductive fiber layer” is preferably a glass fiber layer, but may be a urethane fiber layer or other fiber layer having no conductivity.
“Hoop winding” refers to winding a fiber around the body of the metal liner in the circumferential direction, and “helical winding” refers to one dome of the metal liner mainly for winding the dome. It refers to winding in a spiral from the part to the other dome part through the body part.

  In the present invention, the innermost layer in contact with the metal liner is an insulating layer made of a non-conductive fiber layer, and at least three layers of carbon fiber hoop-wrapped fiber layers and carbon fiber helically-wrapped fiber layers are alternately arranged outside the insulating layer. The carbon fiber layers are sequentially laminated to form a total of 6 or more layers, and the insulating layer is formed to be thinner than each carbon fiber layer, thereby reducing the axial shrinkage difference between the metal liner and the carbon fiber layer. While absorbing, the high pressure resistance and fatigue resistance can be improved.

The figure which shows the cross-section of the elongate high-pressure vessel in which the reinforcement fiber layer concerning this invention was formed. The partially expanded sectional view of FIG. The figure which graphed the relationship between the number of cycles in the durability performance test at 45 MPa, and the thickness (Th) of the number of helically wound carbon fibers. The figure which shows the simulation sample used for a thermal contraction difference absorption test. The figure which shows an example of the calculation data of a synthetic elastic modulus when changing the thickness of a glass fiber layer with respect to a carbon fiber layer of fixed thickness. The figure which shows an example of the calculation data of a synthetic elastic modulus when changing the thickness of a glass fiber layer with respect to a carbon fiber layer of fixed thickness.

  Embodiments of a long high-pressure vessel according to the present invention will be described below with reference to the drawings. Here, a long high-pressure container having a working pressure of 35 MPa and 45 MPa (a container that clears a pressure test at 35 MPa and 45 MPa) will be described as an example. FIG. 1 is a view showing a cross-sectional structure of a long high-pressure vessel according to an embodiment of the present invention, and FIG. 2 is a partially enlarged cross-sectional view thereof.

  The long high-pressure vessel A is composed of a metal liner 1 serving as a main body portion of the vessel and a reinforcing fiber layer 10 wound around the outer periphery thereof. The container A corresponds to a T6 test container in Tables 1 and 2 described later.

As the material of the metal liner 1, an aluminum alloy (A6061 material) that is lightweight and has excellent pressure resistance is used.
In the metal liner 1, bowl-shaped dome portions 3 a and 3 b are formed on the left and right sides of the cylindrical body portion 2. Small-diameter mouth portions 4a and 4b are formed on the opposite sides of the dome portions 3a and 3b to the body portion 2. Screw holes are formed on the inner surfaces of the mouth portions 4a and 4b, a gas inlet / outlet valve (not shown) is provided in one mouth portion 4a, and a sealing plug 4c is provided in the other mouth portion 4b. It is attached.

  The thickness of the metal liner 1 is formed so that the body portion 2 is thinner than the dome portions 3a and 3b, and the dome portions 3a and 3b are closest to the mouth portions 4a and 4b (also called the port side). It is thick and thins as it approaches the body 2. This is to reduce the weight of the metal liner 1 as much as possible, and to strengthen the dome portions 3a and 3b that are easily broken when stress is easily concentrated.

If the thickness of the metal liner 1 is made too thin for weight reduction, it is necessary to reinforce that portion with a reinforcing fiber layer. Therefore, the thickness of the metal liner 1 depends on the working pressure (gas filling pressure) and the reinforcement. It is necessary to make the wall thickness balanced in consideration of the number and thickness of the fiber layers.
From a practical viewpoint, the long high-pressure vessel A is required to have a working pressure (gas filling pressure) of 35 MPa or more. Among the dome portions 3a and 3b at this operating pressure, the dome portion on the side of the mouth portions 4a and 4b (port side) that is not reinforced by the reinforcing fiber layer is set to a minimum thickness of 8 mm or more so The thickness of the fiber is set to at least 3 mm so as to balance the thickness required for the reinforcing fiber layer. And as the operating pressure increases, the thickness of the dome is increased. For example, the dome thickness on the mouth side (port side) is set to 35 mm or more at a working pressure at 82 MPa, which will be described later.

  Further, in order to increase the gas filling inner volume of the metal liner 1, the length between the dome portions 3a and 3b is set to 2 m or more. However, if the length is too long, the ease of use in transportation becomes worse.

Next, the reinforcing fiber layer 10 will be described. The reinforcing fiber layer 10 is a resin-impregnated glass fiber layer (GFRP) 11 that is wound on the innermost side, and a resin-impregnated hoop-wound carbon fiber layer (hoop-wound CFRP) that is alternately laminated thereon and formed at least three layers. ) 12, 14, 16, and 18 and resin-impregnated helically wound carbon fiber layers (helically wound CFRP) 13, 15, and 17. The hoop-wrapped carbon fiber layer and the helical-wrapped carbon fiber layer further increase the number of layers as the operating pressure (gas filling pressure) increases.
Further, as the protective layer for protecting the fiber layer from external impact, a resin layer (for example, an epoxy resin layer) or another glass fiber layer may be coated on the outermost layer.

  The glass fiber layer 11 is a non-conductive fiber layer, is formed by helical winding so as to cover the entire outer peripheral surface from the dome portion 3a to the dome portion 3b, and functions as an insulating layer for preventing electrolytic corrosion. It is. The thickness of the glass fiber layer 11 is about 0.8 mm. In addition, the thickness of this glass insulating layer shall be 0.3 mm or more and 0.9 mm or less, and the glass fiber layer 11 shall be thinner than the thickness of any one of each carbon fiber layer 12-17, and a helical wound fiber layer Even so, it is not a reinforcing fiber layer for reinforcing the strength in the axial direction, but only serves as an insulating layer and a heat shrinkage absorbing layer during the manufacturing process.

  A hoop-wrapped carbon fiber layer 12 is formed on the outside of the glass fiber layer 11 to wind the body portion 2 in the circumferential direction and reinforce the circumferential strength. Further, a helically wound carbon fiber layer 13 for winding the dome portion 3a to the dome portion 3b and reinforcing the strength in the axial direction is formed thereon. The helically wound carbon fiber layer 13 covers the hoop-wrapped carbon fiber layer 12 on the trunk portion 2 and covers the glass fiber layer 11 on the dome portions 3a and 3b. And similarly, it forms so that the hoop winding carbon fiber layer 14, the helical winding carbon fiber layer 15, the hoop winding carbon fiber layer 16, the helical winding carbon fiber layer 17, and the hoop winding carbon fiber layer 18 may be laminated | stacked. In this way, a large number of carbon fiber layers are formed so that six or more layers are formed, and the number of layers (boundary surfaces) between the helically wound carbon fiber layer and the hoop-wrapped carbon fiber layer is six or more.

  In the reinforcement by the carbon fiber layer, the strength in the circumferential direction increases depending on the sum of the thicknesses of the hoop-wrapped carbon fiber layers 12, 14, 16, and 18, and the helical strength in the axial direction is increased. Although the strength increases depending on the sum of the thicknesses of 13, 15, and 17, the rate of increase in strength with respect to the increase in thickness eventually decreases. For both the hoop-wrapped carbon fiber layer and the helical-wrapped carbon fiber layer, the total thickness is set in a range where the burst pressure and the number of cycles satisfy the design values. 11.9 mm (about 3 mm per layer), and the helical winding thickness is 13.7 mm (about 4.6 mm per layer). The thickness of each carbon fiber layer is set to be much larger than the thickness of the glass fiber layer 11 set to 0.8 mm, and each carbon fiber layer 11 is exclusively made without burdening the glass fiber layer 11 with a part of the reinforcing effect. The fiber layer works as a reinforcing layer.

  The 35 MPa long high-pressure vessel A produced in this way has a durability exceeding 50,000 times in the cycle number test at a burst pressure of 200 MPa or more and 35 MPa as shown in the durability performance test data (T6) described below. Performance was obtained, and an excellent long high pressure vessel could be obtained.

(35MPa, 45MPa durability performance experiment)
Specific examples of the present invention will be described. With the comparative example of several long high-pressure containers, the long high-pressure container of the present invention shown in FIG. 1 is manufactured, and the burst pressure (high pressure resistance) when the pressure continues to rise until it bursts as durability performance The durability performance was compared by measuring the number of cycles (fatigue resistance) when repeated pressurization and pressure reduction was repeated at 35 MPa or 45 MPa. Tables 1 and 2 show the form and measurement results of the long high-pressure vessel used for the test. Tests T1 to T5 are comparative examples using comparative products, and T6 is an example of the present invention.

T1 to T6 all have a total thickness of the hoop-wrapped carbon fiber layer of 11.9 mm, but the number of layers is T1, T2 is one layer, T3 is two layers (about 6 mm per layer), T4 , T5 has three layers (about 4 mm per layer), and T6 has four layers (about 3 mm per layer).
For the helically wound carbon fiber layer, the total thickness is changed in the range of 0 mm to 13.7 mm, but T3 is one layer, T4 is two layers (about 3.2 mm per layer), and T5 is four layers ( 3.4 mm per layer), and T6 is 3 layers (about 4.6 mm per layer). Further, at T6, a glass fiber layer of 0.8 mm is provided.

  As a result, among the comparative examples, those without the helically wound carbon fiber layers of T1 and T2 were ruptured before being pressurized to 35 MPa. At T3, T4, and T5, as the total thickness of the helically wound carbon fiber layer increases, both the burst pressure and the number of cycles increase. At T5, the number of cycles is 30,000 or more at 35 MPa, and 10,000 or more at 45 MPa. Cleared.

On the other hand, in T6 which is an example of the present invention, a glass fiber layer having a thickness of 0.8 mm thinner than that of T5 of the comparative example is provided as an insulating layer, but the number of cycles is 35 MPa compared to T5. The number of cycles increased to 50,000, and the number of cycles increased to 20000 or more at 45 MPa, and the fatigue resistance was remarkably improved.
FIG. 3 is a graph showing the relationship between the number of cycles in the durability performance test at 45 MPa in Table 2 and the thickness (Th) of the helically wound carbon fibers.

Originally, glass fibers are weaker than carbon fibers, so that the reinforcing effect is hardly affected by simply adding a thin glass fiber layer of about 0.8 mm, which is the difference between T5 and T6, as an insulating layer. However, there was a big improvement in the increase in the number of cycles.
From this result, the insulating layer consisting of the innermost glass fiber layer plays an important role in the strength (especially the number of cycles that are fatigue resistant) in addition to the total thickness of the helically wound carbon fiber layer. There was found.

  As a result of pursuing this cause, it was found by a thermal expansion difference absorption test described below that the glass fiber layer (insulating layer) has an effect of preventing delamination between the liner and the innermost layer. .

In general, a manufacturing process of a high-pressure container in which a resin-impregnated reinforcing fiber layer is formed includes a resin curing process in which a resin is cured on an intermediate processed product in which the reinforcing fiber layer is wound around the outer periphery of a metal liner. In the resin curing step, it is heated to about 100 ° C. to 150 ° C., but at the time of cooling after the curing, due to the influence of the difference in thermal expansion coefficient between the metal liner and the resin-impregnated reinforcing fiber, An axial force works between the innermost layer and the innermost layer.
Therefore, in order to measure how much deviation (delamination) occurs at the boundary between the metal liner and the innermost layer due to cooling after the resin curing step, measurement was performed using a simulation sample.

(Heat shrinkage difference absorption test)
In order to confirm the influence of thermal expansion, as shown in FIG. 4, a resin layer 1 (epoxy) and a resin layer 2 (araldite) are formed as non-conductive layers (insulating layers) on the outer peripheral surface of a 3000 mm aluminum pipe (6061 material). Then, an intermediate processed product was formed in which a resin-impregnated urethane fiber layer and a resin-impregnated glass fiber layer were formed, and a helically wound carbon fiber layer was formed to a thickness of 5 mm. The resin layer and resin fiber layer of this intermediate processed product were 2800 mm wide, and the aluminum pipes were exposed by 100 mm at both ends.
And it heated at 130 degreeC for the predetermined time until each resin hardened | cured, and after the resin hardened | cured, the heating was stopped and it was allowed to cool naturally. The temperature of the pipe during cooling is monitored, and the length of the exposed aluminum part at the left end at the first measurement time when the pipe temperature becomes 80-90 ° C during the cooling and the second measurement time when the pipe temperature drops to 25 ° C. The length L1 and the length L2 of the exposed aluminum portion at the right end were measured.
Then, the sum of the length L1 and the length L2 is used as the expansion amount at each time point (each temperature), and the difference in interlayer displacement due to the temperature difference at these time points is determined from the difference in expansion amount between the first measurement time point and the second measurement time point. Asked. Table 3 shows the results.

When the resin layer 1 and the resin layer 2 that do not include the fiber layer are the insulating layers, the amount of misalignment is 4.5 mm and 3.5 mm, whereas in the case of the insulating layer that includes the glass fiber, this temperature change The amount of misalignment between the layers was 0 mm, and it was found that no peeling occurred due to the temperature change during this period. Even in the case of an insulating layer containing urethane fiber instead of glass fiber, the amount of misalignment was suppressed to 2 mm, and it was found that peeling was suppressed.
Although the amount of misalignment in the state heated to 130 degrees has not been measured, the amount of misalignment due to temperature change can be determined by using an insulating layer containing glass fibers (or urethane fibers) instead of an insulating layer containing only resin that does not contain fibers. Since the amount is small, it has been found that the peeling phenomenon can be suppressed by forming an insulating layer containing these fibers.

  And, at T6 in Tables 1 and 2, the number of cycles was greatly improved by providing an insulating layer of a 0.8 mm glass fiber layer by the liner, innermost layer (insulating layer) and the glass fiber layer. It is considered that the reinforcing effect was greatly improved because delamination between the layers was suppressed.

Subsequently, an appropriate thickness of the innermost insulating layer was examined. The elastic modulus of glass fiber (GFRP) is 48 GPa, which is about 25% of the elastic modulus of carbon fiber. When the glass fiber layer is wound thickly, the glass fiber layer can be regarded as one coalescence with the adjacent innermost carbon fiber layer, and the synthetic elastic modulus of the coalescence increases as the thickness of the glass fiber layer increases. Smaller than the elastic modulus. If a fiber layer having a small elastic modulus (in this case, a glass fiber layer) is present in the innermost layer, the strain of the liner increases and the number of cycles decreases.
FIG. 5 and FIG. 6 are graphs in which the composite elastic modulus is calculated when the thickness of the carbon fiber layer is changed (3 mm, 5 mm) and the thickness of the glass fiber layer is changed. As the glass fiber layer increases, the synthetic elastic modulus decreases monotonously.

From this point of view, it is preferable from the viewpoint of strength that the insulating layer is made as thin as possible while having a minimum thickness capable of maintaining the function as a relaxation layer that absorbs the shrinkage difference after curing. Therefore, the minimum thickness required to absorb the shrinkage difference after curing is set to 0.3 mm or more. About an upper limit, it is set to 0.9 mm at the maximum as a range which ensures 80% or more when the synthetic elastic modulus of an insulating layer and a carbon fiber layer does not use glass fiber.
By forming the insulating layer (glass fiber layer) in this range, the thickness of the reinforcing fiber layer becomes preferable.

  Next, the number of reinforcing fiber layers for increasing the strength will be described. From the results of the heat shrinkage difference absorption test, it was found that it is preferable that the axial force due to the difference in thermal expansion coefficient during the manufacturing process does not cause delamination. Therefore, if the axial force due to the difference in thermal expansion coefficient is dispersed between a plurality of layers, the difference in the amount of thermal shrinkage can be divided and absorbed between the respective layers, thereby suppressing the peeling, and the metal Separation between the liner and the insulating layer can also be suppressed.

  Specifically, forming three or more hoop winding layers and helical winding layers is considered to contribute to increasing the number of cycles as shown in Tables 1 and 2.

(82 MPa durability performance experiment)
Next, in order to make a long high-pressure vessel having a higher working pressure, a durability performance test was performed on other samples by the same method as in Tables 1 and 2.
Table 4 shows the results. Here, measurements were performed on the comparative products T7 and T8 and the product T9 of the present invention.

  Since the working pressure is high, the liner thickness is made sufficiently thicker than in Tables 1 and 2, and T7 to T9 all have a dome thickness of 37.0 mm on the mouth side and a dome portion on the trunk side. The thickness was 20.6 mm. Further, the total thickness of the hoop-wrapped carbon fiber layers was 19 mm. Regarding the number of layers, T7 was 3 layers (6.3 mm per layer), and T8 and T9 were 4 layers (4.8 mm per layer). . For the helically wound carbon fiber layer, the total thickness is 24.5 mm for T7, 36.8 mm for T8 and T9, T7 is 3 layers (8.2 mm per layer), and T8 and T9 are 4 layers (per layer) About 9.2 mm). At T9, a glass fiber layer of 0.8 mm is provided.

As a result, in the comparative examples T7 and T8, as the total thickness of the helically wound carbon fiber layer increases, both the burst pressure and the number of cycles increase. At 82 MPa, T7 is 15000 times or more, and T8 is 37000. It was more than the number of cycles.
On the other hand, in T9 further provided with a 0.8 mm glass fiber insulating layer, the number of cycles increases to 53,000 times or more compared to T8, and even in this case, the innermost glass fiber insulating layer As a result, peeling due to axial force is suppressed, and fatigue resistance is greatly improved.

  The present invention is used for a long high-pressure vessel used for pressurizing and filling hydrogen and other gases.

A Long high pressure vessel 1 Metal liner 2 Body 3a, 3b Dome 4a, 4b Mouth (port)
10 Fiber layer 11 Glass fiber layer (non-conductive fiber layer)
12, 14, 16, 18 Hoop winding carbon fiber layer 13, 15, 17 Helical winding carbon fiber layer

Claims (3)

An outer peripheral surface of a metal liner having a cylindrical body portion and dome portions extending at both ends of the body portion, and formed so that the total length between the dome portions on both sides is 2 m or more and 6 m or less. In addition, a long high-pressure container having a structure in which fibers impregnated with a thermosetting resin are wound,
A non-conductive fiber layer is formed as an insulating layer on the innermost side in contact with the metal liner,
At least three layers of carbon fiber hoop-wrapped fiber layers and carbon fiber helically-wrapped fiber layers are sequentially laminated on the outside of the insulating layer to form a total of six or more carbon fiber layers,
The insulating layer is a long high-pressure vessel formed thinner than any of the carbon fiber layers.   The long high-pressure container according to claim 1, wherein the insulating layer is a non-conductive fiber layer made of a glass fiber layer, and the insulating layer has a thickness of 0.3 mm or more and 0.9 mm or less.   The long high-pressure vessel according to claim 2, wherein the thickness of each carbon fiber layer is 3 mm or more.

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