JP5840961B2 - High pressure fluid tank and manufacturing method thereof - Google Patents

Description

  The present invention relates to a high-pressure fluid tank manufactured by a filament winding method.

  As a method for producing a high-pressure fluid tank, a filament winding method (hereinafter also referred to as “FW method”) is known. In the FW method, a high-strength fiber-reinforced resin layer is formed by winding a plurality of reinforcing fibers impregnated with a thermosetting resin in advance around the outer periphery of a tank container, also called a liner, and thermosetting the thermosetting resin. It forms in the surface layer of a liner (the following patent documents 1 grade). In the high-pressure fluid tank manufactured by the FW method, durability against the high-pressure fluid is ensured by this fiber reinforced resin layer. However, the durability of the high-pressure fluid tank is required to be further improved.

JP 2010-253789 A JP 2010-223243 A

  An object of this invention is to provide the technique which improves the durability of a high pressure fluid tank.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples. One aspect of the present invention is a high-pressure fluid tank in which an outer surface of a liner is covered with a fiber reinforced resin layer having a reinforced fiber and a thermosetting resin that thermosets and binds the reinforced fibers. The maximum width of the void along the winding direction of the reinforcing fiber present in the region of 30% or less of the thickness of the fiber reinforced resin layer from the outer surface of the liner in the fiber reinforced resin layer is the fiber width in the reinforcing fiber. It is provided as a high-pressure fluid tank having a mean diameter of 100 times or less.

[Application Example 1]
A high-pressure fluid tank in which the outer surface of the liner is coated with a fiber reinforced resin layer having a reinforced fiber and a thermosetting resin that thermosets and binds the reinforced fibers;
The fiber reinforced resin layer has a maximum width in an area of 30% or less of the thickness of the fiber reinforced resin layer from the outer surface of the liner, the maximum width of which is 100 times or less the average diameter of the fibers in the reinforced fiber. A high-pressure fluid tank having a gap along the winding direction.
According to this high-pressure fluid tank, since there is no void in the fiber reinforced resin layer that reduces the durability of the high-pressure gas tank, the durability of the high-pressure fluid tank is improved.

[Application Example 2]
A method for producing a high-pressure fluid tank according to Application Example 1, wherein the liner in which the reinforcing fiber impregnated with the thermosetting resin is wound around an outer surface is periodically increased or decreased by induction heating. The manufacturing method of forming the fiber reinforced resin layer by thermosetting the thermosetting resin by heating while heating.
With this manufacturing method, local overheating in the fiber layer formed of the reinforcing fibers is prevented so that voids that reduce the durability of the high-pressure gas tank are not generated in the fiber-reinforced resin layer. While suppressing the generation, a thermosetting process by induction heating can be performed.

  The present invention can be realized in various forms. For example, a high-pressure fluid tank manufacturing method and manufacturing apparatus, a computer program for realizing the function of the method or apparatus, and the computer program are recorded. It can be realized in the form of a recording medium or the like. The present invention can be realized in the form of a high-pressure fluid tank manufactured by the above-described manufacturing method and manufacturing apparatus, a fuel cell system including the high-pressure fluid tank, a vehicle equipped with the high-pressure fluid tank, and the like.

Schematic which shows the structure of a high pressure gas tank. Explanatory drawing which shows the procedure of the manufacturing process of a high pressure gas tank. Schematic which shows the structure of a thermosetting processing apparatus. The schematic diagram for demonstrating the space | gap formed in a fiber reinforced resin layer. Explanatory drawing for demonstrating the stress which arises in the fiber reinforced resin layer of a cylinder part at the time of use of a high pressure gas tank. Explanatory drawing for demonstrating the stress distribution in the fiber reinforced resin layer of a cylinder part. Explanatory drawing for demonstrating the relationship between the maximum value of the width | variety of the space | gap which exists in an inner layer side area | region, and the destructive pressure of a high pressure gas tank. Explanatory drawing for demonstrating the intermittent heat processing which a thermosetting processing apparatus performs.

A. Example:
1A and 1B are schematic views showing the configuration of a high-pressure gas tank as an embodiment of the present invention. FIG. 1A is a schematic cross-sectional view of the high-pressure gas tank 10 cut along a cut surface passing through the central axis CX, and FIG. 1B is a high-pressure in BB cutting shown in FIG. 2 is a schematic cross section of a gas tank 10. The high-pressure gas tank 10 stores high-pressure gas such as hydrogen and is mounted on a fuel cell vehicle or the like.

  The high-pressure gas tank 10 has a substantially cylindrical cylinder portion 11 that constitutes a main body barrel portion, and a substantially hemispherical dome portion 12 that constitutes mirror portions at both ends of the cylinder portion 11 (FIG. 1A). The high-pressure gas tank 10 is manufactured by a so-called FW method, and has a configuration in which a fiber reinforced resin layer 21 is formed on the outer surface of a liner 20 that is a resin tank container. In addition, a cap portion 13 to which components such as piping and valves for circulating high-pressure gas are attached is provided at the tops of the two dome portions 12.

  FIG. 2 is a flowchart showing a procedure for manufacturing the high-pressure gas tank 10. In step S10, the liner 20 is prepared. In step S20, ribbon-like (band-like) carbon fibers (hereinafter referred to as “reinforcing fibers”) are prepared in which the outer surface of the liner 20 is impregnated with a thermosetting resin such as an epoxy resin in advance. The reinforcing fibers are wound around the outer surface of the liner 20 by so-called hoop winding or helical winding, so that a fiber layer is formed on the outer surface of the liner 20.

  In addition, when forming a fiber layer, it is so preferable that the winding tension of a reinforced fiber is large, and specifically, it is desirable that the winding tension per unit area is 10 Mpa or more. By increasing the winding tension of the reinforcing fiber, loosening of the reinforcing fiber during the thermosetting treatment can be suppressed, and the generation of voids described later can be suppressed. In step S <b> 30, a thermosetting process for thermosetting the thermosetting resin in the fiber layer is performed to form the fiber reinforced resin layer 21.

  FIG. 3 is a schematic diagram showing the configuration of the thermosetting apparatus 100 used in step S30. FIG. 3 illustrates a state in which the liner 20 having the fiber layer 21 a is attached to the thermosetting apparatus 100. The thermosetting processing apparatus 100 includes a control unit 101, a liner attachment unit 110, and an induction heating unit 120.

  The control unit 101 can be configured by a microcomputer including a main storage device and a central processing unit, and controls each component of the thermosetting processing apparatus 100. In addition, although the control part 101 controls the induction heating part 120 and performs an intermittent heating process, the detail is mentioned later.

  The liner attachment portion 110 holds the liner 20 so as to be rotatable at a predetermined rotation speed about the central axis CX. The liner mounting portion 110 includes first and second shafts 111a and 111b, first and second support pillars 112a and 112b, a rotation driving portion 113, and a base portion 115.

  The first and second shafts 111 a and 111 b are inserted into the base portions 13 of the respective dome portions 12 along the central axis CX, and are fitted and connected to the liner 20. The second shaft 111 b is connected to the rotation drive unit 113. The rotation driving unit 113 can be configured by a motor, for example, and generates a rotation driving force according to a command from the control unit 101, and the second shaft 111 b transmits the rotation driving force to the liner 20.

  The first and second support columns 112 a and 112 b are fixed to the base portion 115. The first support column 112a is provided with a bearing portion that rotatably holds the first shaft 111a. The second support column 112b holds the rotation drive unit 113 at a position where the heights of the first and second shafts 111a and 111b are aligned so that the central axis CX of the liner 20 is substantially horizontal.

  The induction heating unit 120 includes a coil conducting wire 121, a high frequency power source 122, and a matching panel 123. The coil conducting wire 121 is wound in parallel to a virtual plane through which the central axis CX passes so as to surround the entire liner 20 held by the liner attaching portion 110. In addition, the coil conducting wire 121 is connected to the matching board 123. The high frequency power supply 122 supplies a high frequency current to the coil conducting wire 121 through the matching board 123.

  The thermosetting processing apparatus 100 heats the thermosetting resin of the fiber layer 21a by heating for a predetermined time by induction heating while rotating the liner 20 on which the fiber layer 21a is formed at a predetermined rotation speed. . With this thermosetting treatment by induction heating, the inside of the fiber layer 21a can be rapidly heated, the processing time of the thermosetting treatment can be shortened, and the fiber-reinforced resin layer 21 is efficiently formed. can do.

  Here, the inventor of the present invention observes a cross section of the fiber reinforced resin layer 21 formed by induction heating with a microscope, so that a void is generated in the boundary region between the reinforced fibers of the fiber reinforced resin layer 21. Found that there is a case. And it discovered that this space | gap became a starting point from which the stress concentration in the fiber reinforced resin layer 21 generate | occur | produced, and caused the fall of durability of the high-pressure gas tank 10. FIG. Specifically, it is as follows.

  FIG. 4 is a schematic diagram for explaining the voids 24 formed in the fiber reinforced resin layer 21. 4 is a schematic cross-sectional view of the high-pressure gas tank 10 similar to that in FIG. 1A, and an example of the position where the air gap 24 is generated is schematically illustrated by a broken line. The lower part of FIG. 4 illustrates a partial schematic cross section of the fiber reinforced resin layer 21 when the portion where the gap 24 is formed is viewed in the direction along the central axis CX.

  Here, in the cylinder part 11 of the high-pressure gas tank 10, a hoop layer is formed in which the reinforcing fibers 22 are wound in a superimposed manner by hoop winding with the winding direction being an angle substantially perpendicular to the central axis CX. In the hoop layer, the reinforcing fibers 22 are arranged adjacent to each other in the direction along the central axis CX and are laminated in the radial direction of the cylinder portion 11. A thermosetting resin 23 that is thermoset exists in the boundary region between the reinforcing fibers 22 that are closely adjacent to each other.

  However, in the thermosetting treatment by induction heating, heat generation of the reinforcing fibers 22 in the fiber layer is induced and the thermosetting resin 23 is thermoset, so that heat is easily trapped inside the fiber layer, and the temperature inside the fiber layer is increased. An excessive temperature rise that is higher than the target temperature tends to occur locally. Such local overheating may cause decomposition of the sizing agent applied to the surface of the reinforcing fiber and outflow of the thermosetting resin 23 from the boundary between the reinforcing fibers 22. In this case, a tubular void 24 is generated in the hoop layer in the fiber reinforced resin layer 21 along the winding direction of the reinforcing fibers 22 (the circumferential direction of the cylinder portion 11).

  FIG. 5 is an explanatory diagram for explaining the stress generated in the fiber reinforced resin layer 21 of the cylinder portion 11 when the high-pressure gas tank 10 is used. FIG. 5 shows a schematic cross section of the cylinder portion 11 of the high-pressure gas tank 10 similar to FIG. 1 (B).

  Here, the inner diameter of the fiber reinforced resin layer 21 (the distance from the central axis CX to the boundary between the liner 20 and the fiber reinforced resin layer 21) is a, and the outer diameter of the fiber reinforced resin layer 21 (from the central axis CX to the fiber reinforced resin). The distance to the outer surface of the layer 21 is b. The high-pressure gas tank 10 is filled with high-pressure gas, and its internal pressure is p.

At this time, the stress σ at an arbitrary position P in the fiber reinforced resin layer 21 that is separated from the central axis CX by a distance r (a ≦ r ≦ b) is expressed by the following equation (1). However, in Equation (1), k = b / a and R = r / a.
σ = p · ((k ² / R ² ) +1) / (k ² −1) (1)

  FIG. 6A is a graph showing the stress distribution of the fiber reinforced resin layer 21 in the radial direction of the cylinder portion 11, and the above equation (1) is expressed with the vertical axis as stress σ and the horizontal axis as r axis. It is a graph. FIG. 6B is an explanatory diagram showing a partial schematic cross section of the high-pressure gas tank 10 in correspondence with the r-axis in FIG. In FIG. 6B, the groove-like gap 24 described with reference to FIG. 4 is schematically shown by a broken line.

  The stress σ generated in the fiber reinforced resin layer 21 of the cylinder part 11 when the high-pressure gas tank 10 is used is the liner 20 side (inner layer side) from the outer surface side (outer layer side) of the fiber reinforced resin layer 21 in the radial direction of the cylinder part 11. Gradually increases (solid line graph S in FIG. 6A). Specifically, the stress σ increases in a downwardly convex curve from the outer layer side to the inner layer side. More specifically, the stress σ is a region on the inner layer side (hereinafter referred to as “BD”) between the outer surface of the liner 20 (position indicated by “a”) and the position of 30% of the thickness of the fiber reinforced resin layer 21 (position indicated by “BD”). In the “inner layer side area 21i”).

  However, as shown in FIG. 6B, when the gap 24 is generated in the inner layer side region of the fiber reinforced resin layer 21, stress concentration occurs starting from the gap 24. In particular, the stress concentration that leads to the breakage of the high-pressure gas tank 10 is likely to be caused when the void 24 exists in the inner layer side region 21i where the stress becomes extremely high. When such stress concentration occurs, the stress σ is lower on the outer layer side than the position v of the gap 24 than when no gap 24 is present, but significantly increases on the inner layer side from the position v of the gap 24 (FIG. 6 (A) dashed line graph Sa).

  FIG. 7 is a graph showing the relationship between the maximum value of the width of the gap 24 existing in the inner layer side region 21 i and the breaking pressure of the high-pressure gas tank 10. The inventor of the present invention measured the width of the gap 24 present in the inner layer side region 21i, and sealed the refrigerant in the high-pressure gas tank 10 to measure the internal pressure (breaking pressure) at which the high-pressure gas tank 10 cracks. As a result, when the maximum width of the gap 24 was smaller than a certain value, the burst pressure of the high pressure gas tank increased from P1 to P2. The breaking pressure P2 was a value obtained by increasing the breaking pressure P1 by 10% or more (P2 ≧ P1 × 1.1).

  Here, the durability of the high-pressure gas tank 10 has a correlation with the average diameter of the fibers included in the reinforcing fibers constituting the fiber-reinforced resin layer 21. From this, the inventors of the present invention have obtained the knowledge that the boundary value VW of the maximum width of the void 24 where the breaking pressure increases can be defined by the average diameter d of the fibers in the reinforcing fiber, and the boundary value VW is It was found that the value is close to a value obtained by multiplying the average diameter d of the fibers in the reinforcing fiber by 100 (VW ≦ 100d).

  Therefore, in the high-pressure gas tank 10 of the present embodiment, even when the void 24 exists in the boundary region between the reinforcing fibers 22 in the inner layer side region 21i of the cylinder part 11, the maximum width of the void 24 is It is comprised so that it may become the value below 100 times the average diameter d of a fiber. Specifically, for example, when the average diameter d of the fibers in the reinforcing fiber is about 7 μm, the maximum width of the gap 24 is set to 700 μm or less. As a result, the stress 24 is suppressed from occurring in the fiber reinforced resin layer 21 of the cylinder portion 11 due to the gap 24 generated by induction heating, and the durability of the high-pressure gas tank 10 is improved.

  In the high-pressure gas tank 10, when a void 24 is generated in the fiber reinforced resin layer 21 of the cylinder portion 11, a similar void may be generated in the fiber reinforced resin layer 21 of the dome portion 12. The size of the gap in the dome portion 12 has a correlation with the width of the gap 24 in the cylinder portion 11. Therefore, if the gap 24 of the cylinder portion 11 is formed with such a width that the deterioration of the durability of the high-pressure gas tank 10 is suppressed, the gap of the dome portion 12 does not cause a decrease in the durability of the high-pressure gas tank 10. Formed in size.

  Here, the width of the gap 24 of the fiber reinforced resin layer 21 tends to increase as the degree of local overheating that occurs during the thermosetting process increases. Therefore, in order to set the width of the gap 24 to a value not more than 100 times the average diameter of the fibers in the reinforcing fiber, the thermosetting apparatus 100 of this embodiment (FIG. 3) performs the intermittent heat treatment described below. Execute to suppress the occurrence of local overheating.

  FIGS. 8A and 8B are explanatory diagrams for explaining the intermittent heating process performed by the thermosetting apparatus 100. FIG. 8A illustrates a graph illustrating an example of a temporal change in the heating temperature during the execution of the intermittent heat treatment. In FIG. 8B, a timing chart showing the timing at which current is supplied to the coil conductor 121 during the intermittent heating process is made to correspond to the time axis of the graph of FIG. It is illustrated.

After the heating of the liner 20 on which the fiber layer 21a is formed, the control unit 101 stops the supply of high-frequency current to the coil conductor 121 when the temperature of the fiber layer 21a reaches the first temperature Ta (OFF) And the heating is temporarily stopped (time t ₁ , t ₃ , t ₅ , t ₇ ,...). Then, the temperature of the fiber layer 21a is, when lowered to a second temperature Tb, resuming the supply of the high-frequency current to the coil wires 121 to (ON), resume heating (time t _2, t _4, t ₆ , ...). The control unit 101 repeats the heating stop and restart for a predetermined time (for example, about 30 minutes).

  Here, this intermittent heat treatment is a treatment in which heating and cooling are repeated so that the maximum temperature in the fiber layer due to heating does not cause problems of materials such as the thermosetting resin 23 and the sizing agent contained in the fiber layer. It is. For this reason, the first temperature Ta is preferably set to a value equal to or lower than the temperature at which such a defect in the fiber layer occurs. For example, in general, the thermosetting resin 23 and the sizing agent are defective at a temperature of 200 ° C. or higher. Therefore, in order to set the maximum temperature in the fiber layer to less than 200 ° C., the first temperature Ta is preferably set to about 140 to 150 ° C.

  In contrast, the second temperature Tb is restarted at a period (for example, about 2 to 3 minutes) in which the temperature of the thermosetting resin 23 does not decrease too much during the thermosetting. It is preferable to set at such a temperature. Specifically, when the first temperature Ta is set within the range of 140 to 150 ° C., the second temperature Tb is preferably set at a temperature within the range of 110 to 120 ° C. .

  Thus, in the thermosetting processing apparatus 100, the temperature of the fiber layer 21a is periodically lowered by intermittently performing heating for thermosetting, and local overheating in the fiber layer 21a is generated. Suppress. Thereby, generation | occurrence | production of the space | gap 24 which has the width | variety used as the cause of the durable fall of the high pressure gas tank 10 can be suppressed. In addition, the control part 101 does not need to perform a stop and restart of a heating based on the temperature of the fiber layer 21a. The control unit 101 may periodically stop and restart heating at a predetermined time interval (for example, every few minutes).

  As described above, with the high-pressure gas tank 10 of the present embodiment, the presence of the void 24 having a width that causes a decrease in the durability of the high-pressure gas tank 10 in the inner layer side region 21 i of the fiber reinforced resin layer 21 is suppressed. Has been. Therefore, the durability of the high-pressure gas tank 10 is improved.

DESCRIPTION OF SYMBOLS 10 ... High pressure gas tank 11 ... Cylinder part 12 ... Dome part 13 ... Cap part 20 ... Liner 21 ... Fiber reinforced resin layer 21a ... Fiber layer 21i ... Inner layer side area 22 ... Reinforcement fiber 23 ... Thermosetting resin 24 ... Air gap 100 ... Heat Curing apparatus 101 ... Control unit 110 ... Liner mounting portion 111a ... first shaft 111b ... second shaft 112a ... first support column 112b ... second support column 113 ... rotation drive unit 115 ... base unit 120 ... Induction heating section 121 ... Coil conductor 122 ... High frequency power supply 123 ... Matching panel CX ... Center axis

Claims (2)

A high-pressure fluid tank in which the outer surface of the liner is coated with a fiber reinforced resin layer having a reinforced fiber and a thermosetting resin that thermosets and binds the reinforced fibers;
The maximum width of the gap along the winding direction of the reinforcing fibers from the outer surface is present at 30% or less of the area of the thickness of the fiber-reinforced resin layer of the liner in the fiber reinforced resin layer has an average of fibers in the reinforcing fiber der Ru, high pressure fluid reservoir 100 times the diameter. A method for producing a high-pressure fluid tank according to claim 1,
The liner, in which the reinforcing fiber impregnated with the thermosetting resin is wound around the outer surface, is heated by induction heating while periodically increasing or decreasing the heating temperature, thereby thermosetting the thermosetting resin. The manufacturing method which forms the said fiber reinforced resin layer.

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