JP4232210B2 - Fiber reinforced plastic pressure vessel - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to various pressure vessels, in particular, a pressure cylinder made of fiber reinforced plastic (FRP).
[0002]
[Prior art]
In order to reduce the weight and performance of a pressure vessel mounted on a natural gas vehicle, commonly called a CNG tank (Compressed Natural Gas Tank), on the outside of a liner made of metal such as steel or aluminum, or a liner made of plastic such as polyethylene, Pressure vessels formed of fiber-reinforced plastic (hereinafter abbreviated as FRP) made of high-strength fibers such as glass fiber and carbon fiber and resin are developed and marketed mainly in the United States. Also, lightweight FRP pressure vessels are commercially available for use in hospitals and in air respirators used by firefighters.
[0003]
These containers are required to be used in a defined environment, but the natural environment can be severer than the user, and sometimes the designer, predicts.
[0004]
Since normal containers do not have a mechanism for recording temperature, humidity, etc., it cannot be completely denied that containers exposed under conditions that are not considered in the design can cause unexpected situations .
[0005]
To prevent disasters caused by rupture of a gas leak or a container, in order to ensure the safety of the vessel, inspection of regular container is kicked obligated (for example, maintenance standard of High Pressure Gas Safety Institute of Japan HKS-S016) is Oh However, it can be said that it is necessary to keep the environment of the container constant in order to more surely prevent unexpected situations.
[0006]
In order to keep the environment of the container constant, there is a method of keeping the container in a temperature controlled room (so-called temperature control room), but in the case of automobiles, there is not enough room for space and economy to take such measures. The advantage of light weight can be sacrificed.
[0007]
The container itself automatically adjusts the temperature and humidity of the container. In addition, if the container is likely to be damaged leading to an unexpected situation, the container itself informs the user (such as sound and If it can be presented in some form such as light), it is a very preferable container for safety and can be said to be an invention desired by society.
[0008]
[Problems to be solved by the invention]
The object of the present invention is to solve the above-mentioned problems of the conventional pressure vessel and not only to be lightweight, but also to be able to adjust the temperature and humidity of the pressure vessel. To provide a container. Another object is easy inspection of the container, further to provide a pressure vessel which enables and Turkey informs vessel damage status and remaining lifetime to a user on time.
[0009]
Another object of the present invention is to provide a method for manufacturing such a pressure vessel at a low cost.
[0010]
[Means for Solving the Problems]
To achieve the above object, the present invention is a pressure vessel comprising at least one opening, an inner shell made of metal or plastic, and an outer shell made of fiber reinforced plastic (hereinafter referred to as FRP). The fiber reinforced plastic constituting the outer shell contains a conductive fiber for energization made of a metal fiber or a metal-plated, metal-painted, or metal-coated fiber, and the conductive fiber and A pressure vessel is provided in which the reinforcing fibers are coated with an insulator .
[0011]
Further, according to the present invention, as a method of manufacturing such a pressure vessel, the outer shell is formed by winding all or part of the conductive fiber around the inner shell using the filament wind method or the tape wind method. A cylinder manufacturing method is provided.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The kind of gas filled in the pressure vessel of the present invention is not particularly limited, and examples thereof include hydrogen, nitrogen, oxygen, argon gas, acetylene gas, helium gas, and organic gas in addition to the natural gas as described above.
[0013]
The present invention will be described in detail based on one embodiment.
[0014]
In FIG. 1, it has the pressure | voltage resistant outer shell 2 provided so that the inner shell 1 might be covered, and as a whole, it has the trunk | drum 9, the following mirror part 10, and the nozzle attachment part 3 as an opening part. A nozzle mounting bracket 4 is mounted on the nozzle mounting portion, and a nozzle 5 is mounted on the nozzle mounting bracket 4. The FRP constituting the outer shell 2 includes reinforcing fibers 7 and conductive fibers 8.
[0015]
In addition to natural gas, hydrogen, nitrogen, oxygen, argon gas, acetylene gas, helium gas, organic gas, etc. are stored in the pressure vessel at normal pressure (about 1 atm) to 700 atm. Used at a flow rate of In the case of a natural gas vehicle, the flow rate is finely adjusted by a solenoid valve.
[0016]
In the above, the inner shell 1 has a function of preventing gas leakage and a function of bearing a part of pressure resistance (particularly axial pressure resistance), and is made of metal, plastic, or a composite thereof.
[0017]
The metal of the inner shell 1 is made of a light alloy such as steel, an aluminum alloy, a magnesium alloy, or a titanium alloy, for example. The thickness of the metal inner shell may be a thickness of several millimeters for the purpose of preventing gas leakage, but when the purpose is to bear the pressure resistance, the stress calculation by the finite element method (FEM), etc. The wall thickness is usually in accordance with the stress to be borne.
[0018]
The plastic of the inner shell 1 may be made of polyethylene resin, polypropylene resin, polyamide resin, ABS resin, polybutylene terephthalate resin, or a composite layer of these resins.
[0019]
Since the plastic of the inner shell 1 may be required to have a gas barrier property as a plastic liner, the type of resin is selected according to the type of gas.
[0020]
As a manufacturing method of metallic inner shell, in addition to casting and forging, the cylindrical part (body part) and the hemisphere part (dome part) are welded, or after deep drawing and spinning, the dome part is formed. Any known manufacturing method may be used.
[0021]
As a manufacturing method of the plastic inner shell, any known manufacturing method such as blow molding, rotational molding, injection molding, and heat fusion molding may be used.
[0022]
In order to avoid electrical leakage, the resin inner shell is preferable in relation to the conductive fiber existing in the outer shell described later. However, the metal inner shell is also non-conductive between the outer shell and the outer shell. This can be avoided by providing a layer (for example, providing a reinforcing FRP layer of glass or aramid fiber, an insulating layer such as rubber or paper), coating, plating or the like.
[0023]
On the other hand, the outer shell 2 is a fiber reinforced plastic (FRP) made of carbon fiber and resin used as a reinforcing fiber , which has high strength and high elastic modulus. The conductive fiber for energization is a boundary portion between the liner and the FRP. It is contained inside or on the surface of FRP.
[0025]
This is in terms of weight reduction because the carbon-containing fibers most excellent.
[0027]
The reinforcing fiber is preferably provided with a surface treatment or a sizing agent in order to improve adhesion with a resin described later.
[0028]
Next, the elongation of the reinforcing fiber is preferably 3% or less. This is because if the elongation is higher than this, the conductive fiber described later may be broken before the reinforcing fiber due to impact or the like.
[0029]
Carbon fiber is a fibrous carbon material substantially composed of only carbon elements. There are PAN-based carbon fibers obtained by heating and firing polyacrylonitrile as a raw material, and pitch-based carbon fibers using pitch as a raw material. . Among these, PAN-based carbon fibers are preferable because of their high specific strength. Usually, 3 to 10 strands of 6,000 to 200,000 single yarns are bundled (combined).
[0030]
Since the reinforcing fiber is a carbon fiber , the carbon fiber is coated with an insulating fiber such as a nylon fiber, a polyethylene fiber, or a polyester fiber in order to avoid an electrical short circuit with a conductive fiber such as a metal fiber described later. A covering yarn is applied, an insulating coating is applied, plating is performed, and the like is applied to the insulator. In this case, the weight reduction effect is remarkably improved.
[0031]
Next, as the resin constituting the FRP outer shell of the pressure vessel of the present invention, thermosetting resins such as epoxy resins, unsaturated polyester resins, vinyl ester resins, phenol resins, modified epoxy resins, polyamide resins, polyethylene terephthalate Resin, ABS resin, polyether ketone resin, polyphenylene sulfide resin, poly-4-methylpentene-1 resin, thermoplastic resin such as polypropylene resin, rubber material, and the like can be used. In particular, when a conductive fiber is included, it is preferable that the resin has a glass transition temperature of 80 ° C. or higher with little thermal deterioration due to heat generation due to energization. A resin having a thermal conductivity in the range of 0.1 W / mK to 100 W / mK is preferable.
[0032]
Further, in order to improve the thermal conductivity, metal particles such as aluminum or inorganic particles that increase thermal conductivity such as carbon black may be mixed in the resin.
[0033]
By the way, the ratio between the tensile tension in the axial direction of the pressure vessel caused by the internal pressure and the tensile tension in the circumferential direction is approximately 1: 2. When the inner shell is made of a thick metal and can withstand the pressure resistance in the axial direction, the arrangement angle (winding angle) of the reinforcing fibers is ± 75 ° to the axial direction of the pressure vessel in the body portion of the inner shell. It is preferable to arrange at an angle of ± 105 °, preferably ± 85 ° to ± 100 °.
[0034]
In addition, if the inner shell is made of plastic or is not a thin metal and cannot withstand pressure in the axial direction, the outer shell must also cover the axial pressure resistance. Reinforcing fiber layers disposed at an angle of at least ± 5 ° to ± 50 ° with respect to the axial direction of the container, and an angle of ± 75 ° to ± 105 °, preferably ± 85 ° to ± 100 ° It is preferable to have a configuration of reinforcing fiber layers.
[0035]
Of course, winding configurations other than these winding angles may be used to further improve characteristics such as impact.
[0036]
In addition, since the bending stress by an internal pressure acts on the boundary part of a trunk | drum and an end plate part, it is preferable to comprise a little thickly.
[0037]
Also, if the above-mentioned reinforcing fiber mat or nonwoven fabric-resin FRP layer is interposed between the layers, or if a similar FRP layer is formed as the outermost layer, the impact energy can be dispersed. Thus, impact performance, scratch resistance, and solvent resistance are further improved. Similarly, the outermost layer can be formed as an FRP layer of glass fiber or organic fiber and resin excellent in impact resistance, or can be formed as a resin layer of polyethylene resin, polyamide resin, urethane resin or the like.
[0038]
Then, as the conductive fibers for conduction of the present invention, the steel wire, aluminum wire, copper wire, nichrome wire, various metal fibers, including steel wires, or the metals such as nickel or silver on the surface plated, painted or coated organic fibers and ceramic fibers, and inorganic fibers such as carbon fiber used. Here, the conductive fiber also includes a conductive wire or cable .
[0039]
The conductive fiber for energization of the present invention is a state in which the conductive fibers are electrically continuously connected and can be energized through the conductive fibers. These conductive fibers are connected to energization terminals (electrodes), which will be described later. When energized, the containers generate heat and the container is heated, dried, or measured for electrical properties such as resistance to damage the container. It can be used for detection.
[0040]
Preferred metal fibers as fibers for heating / drying, platinum cross-sectional area in the range of ^{1 × 10 -5 mm 2 ~100mm 2} , tungsten, molybdenum, silver, aluminum, nickel, magnesium, copper, steel, and their Alloy, Ni-Cr alloy (also called Nichrome alloy), Ni-Cr-Fe alloy, Fe-Cr-Al alloy, Fe-Cr-Al-Co alloy, copper-silver alloy, copper-nickel alloy, copper-magnesium It is a round wire-like, strip-like, flattened, flat-fibrous metal fiber, metal wire, or metal cable made of a metal alloy, copper-aluminum alloy, or the like.
[0041]
The reason why the cross-sectional area is within the above range is that heat generation may be insufficient if it is less than this range, and lightness may be impaired if it is more than this range. These fibrous metals can be used as a single wire or as a double wire by twisting them.
[0042]
Also, the same metal or different metal fibers may be combined together, or may be in the form of a surface such as a mesh or fabric, or a sheet.
[0043]
A preferable specific resistance (also referred to as volume resistivity) of the metal and the alloy is preferably in the range of 2 μΩ · cm to 200 μΩ · cm. A metal having a specific resistance in the range of 80 to 200 μΩ · cm is preferable when a rapid and high temperature increase is required, and a metal in the range of 2 to 80 μΩ · cm is preferable when a relatively low temperature increase is required. This is because if the specific resistance is smaller than the above range, it takes too much time to raise the temperature, and if the specific resistance is larger, a large voltage is required. The volume resistivity is measured according to JIS C2525.
[0044]
A copper alloy and a nichrome alloy are preferred at a relatively low temperature rise. Among them, the copper-aluminum alloy-based heating element disclosed in Japanese Patent Laid-Open No. 52-120222 gives appropriate flexibility and specific resistance. Therefore, it is preferable.
[0050]
In addition, since the above-described reinforcing fiber is a carbon fiber , the conductive fiber for energization is coated and coated with an insulator made of ceramic or polymer for the purpose of preventing an electrical short circuit with the conductive fiber, or an insulating property. the Flooding in fiber or film may be subjected to a treatment for coating an insulator.
[0051]
These conductive fibers can be disposed across the inner surface of the outer shell of the container, the inner surface of the outer shell, the surface of the outer shell, or any of these.
[0052]
The inner surface of the outer shell, the inner surface of the outer shell, and the outer shell surface are names from the inner shell side when the wall thickness of the container is divided into 1/3. When the conductive fiber is arranged inside the outer shell , the conductive fiber can be protected by the reinforcing fiber, and when the conductive fiber is arranged on the outer shell surface , the conductive fiber can be repaired. If the conductive fiber is arranged in the same way as the reinforcing fiber, it is most efficient in terms of molding effect, but if you want to detect temperature rise, drying, or damage in a specific direction, arrange it in a different direction from the reinforcing fiber. You may let them.
[0053]
The conductive fiber may be a single long fiber, or may have a planar shape such as a mesh or a woven fabric and may cross each other.
[0054]
Usually, since it is necessary to raise the temperature of the entire container, it is preferable that the conductive fiber covers more than half of the surface area of the container, but the part to be heated is not the entire container, but a part, If it is known in advance, conductive fibers may be arranged at a high density at that location. For example, when it is desired to raise the temperature in the vicinity of the base part, conductive fibers are arranged at a high density in the vicinity of the base part, and when it is desired to heat and dry the body part, the body part is evenly or densely arranged. The conductive fibers may be arranged in an overlapping manner.
[0055]
In the case of object called a container Ru dried, preferably covers more than half of the surface area of the container. Furthermore, it is more preferable that it is located near the surface of the outer shell (outer surface when the thickness of the outer shell is divided into one third) to suppress moisture absorption. Furthermore, it is preferable to use a planar body including a metal foil such as an aluminum foil as a heating element for drying because it can more effectively suppress the ingress of moisture.
[0056]
When detecting the degree of damage to the container, it is preferable that the conductive fiber includes a fiber whose elongation is smaller than that of the reinforcing fiber. Although not particularly limited, the elongation of the conductive fiber is preferably 80% or less of the elongation of the reinforcing fiber. This is because, when the elongation is smaller than that of the reinforcing fiber, it breaks before the reinforcing fiber, and electrical characteristics such as the resistance value of the conductive fiber change more sensitively.
[0057]
Further, when a large number of conductive fibers are wound around the inner shell, this vicinity is a region where both radial and circumferential stresses are large, and early damage can be detected quickly and gas leakage can be prevented. When many are wound around the outer surface of the outer shell, damage from the outside such as an impact caused by a foreign object can be detected at an early stage.
[0058]
Next, terminals for energization (also referred to as electrodes or terminals) are made of copper (including copper alloys), silver, steel, aluminum (including aluminum alloys), etc., and conductive fibers are alloys such as solder or conductive materials. They are connected by being knotted with polymer, or mechanically clamped with screws, springs or caulking.
[0059]
The shape of the terminal may be a convex shape such as a plug, a pin, or a rod, or a concave shape such as a socket, or may be a surface shape without undulations or a surface shape with undulations. When energization is performed irregularly or temporarily without using a dedicated tool or the like, it is preferable because the protrusion can be energized with a clip or the like.
[0060]
More specifically, in order to enable monitoring with a general-purpose tester or the like, a metal terminal with a standard diameter of a banana female terminal may be connected so that a general-purpose terminal such as a commercially available banana terminal can be easily connected. You may provide the thickness part which a clip pinches so that a clip may be connected easily. Further, the screw may be cut off so that it can be connected to other parts by a screw type. The planar shape is preferable because it occupies less space.
[0061]
It should be noted that it is preferable to protect the terminal portion with a cloth or a plastic cover in order to prevent the occurrence of an electrical failure due to damage or contamination of the terminal portion when no power is applied. When the screw is cut or the like, it is preferable to attach and place a lid made of rubber or plastic.
[0062]
It is preferable to install a current-carrying terminal near the base because it can be inspected at the same time when checking nozzles, bases, and valves. It is also possible to energize some of the plurality of terminals to locally raise the temperature or dry it. In this case, the terminal positions may be dispersed in areas other than the opening of the container. Also, the nozzle mounting bracket may be cut off or a terminal connecting structure may be used as a terminal.
[0063]
In the case of damage detection, the accuracy of damage detection is improved by using a combination of two or more terminals.
[0064]
As a method of energization, there are a method of applying a constant voltage (constant pressure method), a method of flowing a constant current (constant current method), and a method of periodically applying a voltage or flowing a current in a pulse shape or a sine wave shape.
[0065]
It is also effective to use a mechanical method such as a bimetal method or a thermostat method to cause a constant voltage or current to flow as the container temperature changes. It is preferable because the temperature of the container can be controlled within a narrow range.
[0066]
Examples of the temperature sensor include a method using a thermocouple, a thermistor temperature sensor, an optical fiber, and a method using a non-contact temperature sensor such as an infrared sensor. Moreover, since the resistance value of the conductive fiber for energization also depends on the temperature, this may be used.
[0067]
In addition, when detecting temperature rise, drying, and damage online, install a meter that displays the resistance value or current (current) as a part of the container. Monitoring and control can be performed from inside the vehicle such as the instrument panel of the driver's seat and from outside the vehicle such as the gas filling port. More preferably, not only the monitor but also a warning buzzer or a warning lamp is lit. More preferably, warning lamps may be provided in multiple stages so that the degree of damage can be recognized at a glance.
[0068]
Next, when the conductive fiber is embedded in the FRP, it may be performed simultaneously with the winding of the reinforcing fiber, or the winding process of the reinforcing fiber may be interrupted once or more to arrange only the conductive fiber. When winding together with the reinforcing fiber, the conductive fiber needs to have process passability equal to or higher than that of the reinforcing fiber, and the reinforcing fiber and the conductive fiber are integrated (for example, by tying them in advance (before the winding process)). There is no problem. In the case where the conductive fiber has a woven fabric or a mesh structure, the warp and / or part of the weft may be a reinforcing fiber.
[0069]
Further, the breaking elongation of the conductive fibers in terms would leave damage detection is preferably less than or equal to the elongation at break of the reinforcing fibers. This is because the conductive fiber breaks at the same time as or before the reinforcing fiber, and the damage of the cylinder can be detected on the safer side.
[0070]
The amount of the conductive fiber to be used is preferably smaller than the reinforcing fiber of FRP that mainly constitutes the outer shell, but increases as the number of places where it is desired to increase the temperature, the place where it is desired to dry, and the number of areas / regions to be detected increases. When the reinforcing fibers of the container outer shell are carbon fibers, all of the FRP reinforcing fibers may be carbon fibers. In this case, the weight of the container can be extremely reduced. In general, the amount of the conductive fiber is preferably 20% or less of the reinforcing fiber except when the reinforcing fiber and the conductive fiber are combined.
[0071]
Next, as a method for molding the container of the present invention, any known molding method such as a filament wind method, a tape wind method, or a pull wind method can be used. Depending on the form, the conductive fibers can be arranged in the same process as the reinforcing fibers or can be arranged off-line.
[0072]
It can also be used to adjust the curing of the resin by energizing the conductive fiber during molding, or to fuse and bond the inner shell and the outer shell.
[0073]
Specifically, when the FRP outer shell after filament winding is cured in an oven, the conductive fibers arranged in the outer shell are energized, and the inner / outer layer difference (resin curing) It is possible to suppress the runaway reaction of the resin due to the reaction heat.
[0074]
If the material of the inner shell is a material having a larger linear expansion coefficient than the FRP of the outer shell, for example, thermoplastic or aluminum, the inner shell and outer shell due to thermal shrinkage after the outer shell is cured To prevent this, the conductive fiber placed inside the outer shell near the inner shell or the inner surface of the outer shell is energized and heated to fuse the inner shell and the outer shell. Can be made. At this time, an adhesive agent, a binder material, a compatibilizer, or the like that melts or reacts with the inner shell material and the outer shell material may be inserted between the inner shell and the outer shell.
[0081]
【The invention's effect】
The pressure vessel of the present invention comprises at least one opening, a metal or plastic inner shell, a pressure vessel comprising a fiber-reinforced plastic outer shell that used carbon fibers as the reinforcing fibers The fiber reinforced plastic constituting the outer shell contains a conductive fiber for energization made of a metal fiber or a metal-plated, metal-painted, or metal-coated fiber, and the conductive fiber and / or the reinforcing fibers may be either et insulator is coated, the temperature of the vessel, the humidity can be adjusted to, the emergency container can be prevented leading to contingencies, if there is a possibility of resulting damage It is a very preferable container for safety that can be detected nondestructively, and can be said to be an invention desired by society.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view of a cylinder according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along line AA ′ of FIG.
[Explanation of symbols]
1: Inner shell 2: Outer shell 3: Nozzle mounting part (opening)
4: Nozzle mounting bracket 5: Nozzle 6: Terminal 7: Reinforcing fiber (bundle)
8: Conductive fiber 9: Body 10: End plate

Claims (9)

A pressure vessel having at least one opening, a metal or plastic inner shell, and a fiber reinforced plastic outer shell using carbon fiber as a reinforcing fiber, which constitutes the outer shell The fiber reinforced plastic includes a metal fiber or a conductive fiber for energization made of metal-plated, metal-painted, or metal-coated fiber, and the conductive fiber and / or the reinforcing fiber includes A pressure vessel that is coated with an insulator . Terminal for energizing the conductive fibers that Yusuke two or more positions, the pressure vessel according to claim 1. Terminal for energization Ru opening near the container, claims 1 to pressure vessel according to 2. The cross-sectional area of the metal fibers Ru der range of ^{1 × 10 -5 mm 2 ~100mm 2} , the pressure vessel according to any one of claims 1 to 3. The volume resistivity of the metal fibers Ru der range of 2μΩ · cm~200μΩ · cm, the pressure vessel according to claim 1. The method of controlling the temperature of this pressure vessel by supplying with electricity to the conductive fiber of the pressure vessel in any one of Claims 1-5 . The method to dry this pressure vessel by supplying with electricity to the conductive fiber of the pressure vessel in any one of Claims 1-5 . By energizing the conductive fibers of the pressure vessel according to any one of claims 1 to 5, a method for monitoring the damage state of the pressure vessel. By energizing the conductive fibers of the pressure vessel according to any one of claims 1 to 5, a method of displaying the remaining life of the pressure vessel.

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