METHOD FOR MANUFACTURING HIGH PRESSURE TANK

The present invention provides a method for manufacturing a high pressure tank having a reinforcing layer on an outer surface of a liner provided with dome portions at both end portions of a round tubular shaped body portion, the method including: a winding process of winding a fiber bundle containing a curable resin and having a predetermined tension on the outer surface of the liner; and a reinforcing layer forming process of forming the reinforcing layer by curing the curable resin contained in the fiber bundle wound around the outer surface, in which the winding process is performed so that the tensions of the fiber bundles at the both end portions are lower than a tension of the fiber bundle at a general portion of the body portion defined between the both end portions.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a method for manufacturing a high pressure tank.

Description of the Related Art

In the related art, a high pressure tank having a reinforcing layer on an outer circumference of a round tubular shaped body portion of a liner is known (for example, see Patent Literature 1).

The method for manufacturing this high pressure tank includes a process of forming a first reinforcing layer on an outer circumference of a body portion of a liner by a hoop winding of a tow prepreg (a fiber bundle containing a curable resin); a process of forming a second reinforcing layer on the first reinforcing layer by a helical winding od the tow prepreg; and a process of curing a curable resin contained in the tow prepreg.

PRIOR ART DOCUMENT(S)

However, in a prior art method for manufacturing a high pressure tank (for example, see Patent Literature 1), when the fiber bundle is wound and overlapped on the entire body portion along the axial direction of the body portion of the liner, the winding of the fiber bundle may be collapsed at both end portions of the body portion. When the winding of the fiber bundle is collapsed, the breaking strength of the reinforcing layer may be reduced.

An object of the present invention is to provide a method for manufacturing a high pressure tank which more reliably increases the breaking strength of a reinforcing layer as compared with the conventional art.

SUMMARY OF THE INVENTION

In order to achieve the object, the present invention provides a method for manufacturing a high pressure tank having a reinforcing layer on an outer surface of a liner provided with dome portions at both end portions of a round tubular shaped body portion, the method including: a winding process of winding a fiber bundle containing a curable resin and having a predetermined tension on the outer surface of the liner; and a reinforcing layer forming process of forming the reinforcing layer by curing the curable resin contained in the fiber bundle wound around the outer surface, in which the winding process is performed so that the tensions of the fiber bundles at the both end portions are lower than a tension of the fiber bundle at a general portion of the body portion defined between the both end portions.

According to the method for manufacturing a high pressure tank of the present invention, the breaking strength of the reinforcing layer can be more reliably increased than in the related art.

DESCRIPTION OF THE INVENTION

Next, an embodiment for carrying out the present invention will be described in detail with reference to the drawings as appropriate. First, a structure of the high pressure tank obtained by the method according to this embodiment will be described.

FIG.1is the longitudinal section view of the high pressure tank1.FIG.2is the partial enlarged side view of the high pressure tank1.

For example, the high pressure tank1of this embodiment is a high pressure tank that is mounted on a fuel cell vehicle and stores hydrogen gas to be supplied to a fuel cell system. However, the high pressure tank1is not limited to this. The high pressure tank1may be a high pressure tank used for another high pressure gas.

As shown inFIG.1, a high pressure tank1includes a liner2, a mouthpiece3connected to the liner2, and a reinforcing layer4covering the outside of the mouthpiece3from the liner2.

For example, the mouthpiece3is formed of a metal material such as aluminum alloy. The mouthpiece3includes a cylindrical mouthpiece body3ahaving a feed/discharge hole therein and a flange portion3aformed at one end of the mouthpiece body3bin the axial direction.

The liner2is a hollow body made of thermoplastic resin. For example, the thermoplastic resin may be a polyamide resin, a polyethylene resin, or the like, but is not limited thereto.

The liner2of this embodiment includes a round tubular shaped body portion5and dome portions6integrally formed at both ends of the body portion5.

As shown inFIG.1, the dome portion6is a flat bowl-shaped body which is gradually reduced in diameter as it goes away from the body portion5side to the outside in the Ax-axis direction.

The radial central portion of the dome portion6is recessed to correspond to the shape of the flange portion3bof the mouthpiece3.

As shown inFIG.1, the reinforcing layer4is formed from the outer surface of the liner2to the outer surface of the mouthpiece3.

As will be explained in detail later, the reinforcing layer4is formed by curing a curable resin contained in a tow prepreg wound around the mouthpiece3from the liner2.

The tow prepreg of this embodiment is formed of a fiber bundle (tow) of a reinforcing fiber containing the curable resin, and has adhesiveness.

For example, the curable resin of the tow prepreg may be a thermosetting resin such as an epoxy resin, a phenol resin, an unsaturated polyester resin, a polyimide resin, or the like, but is not limited thereto.

In addition, for example, the reinforcing fiber may be a carbon fiber, a glass fiber, an aramid fiber, boron fiber, an alumina fiber, a silicon carbide fiber, or the like, but is not limited thereto.

As shown inFIG.2, the reinforcing layer4is composed of a plurality of unit layers7laminated on the outer surface of the liner2. The reinforcing layer4of this embodiment is composed of nine unit layers7in the body portion5of the liner2, but the number of the unit layers7is not limited to this.

The unit layer7is formed by arranging bands B (seeFIG.3), which are band-shaped fiber bundles fed from a band feeding head13bin a manufacturing equipment10(seeFIG.3) described later, in parallel in the axial direction of the liner2(the direction perpendicular to the paper surface ofFIG.2).

These unit layers7are integrated in a reinforcing layer forming process in which the curable resin of the tow prepreg is cured. The reinforcing layer forming process will be described later.

Next, the manufacturing equipment10of the high pressure tank1will be described.

FIG.3is a configuration diagram of the manufacturing equipment10.

As shown inFIG.3, the manufacturing equipment10includes a feeding mechanism11for feeding the tow prepreg P, a guiding mechanism12for guiding the tow prepreg P fed from the feeding mechanism11to a winding mechanism13, and the winding mechanism13for winding the tow prepreg P guided by the guiding mechanism12around the liner2.

The feeding mechanism11includes a plurality of bobbin shafts11aaround which the tow prepreg P is traverse wound, and a bobbin shaft motor (not shown) that assists rotation of the bobbin shafts11aso that the tow prepreg P is pulled out from each bobbin shaft11aat a predetermined tension. In the feeding mechanism11of this embodiment, the number of bobbin11ais five. However, the number of the bobbin11ais not limited to this. The number of bobbin11acan be changed as required.

The guiding mechanism12includes a plurality of guiding rollers12aover which the tow prepreg P is stretched. The guiding roller12ahas a plurality of guiding circumferential grooves (not shown) to individually guide the plurality of tow prepreg P fed from the feeding mechanism11. These guiding circumferential grooves have a flat bottom face with a predetermined width. The tow prepreg P travels from the feeding mechanism11on the upstream side to the winding mechanism13on the downstream side while abutting against the bottom faces of the guiding circumferential grooves. As a result, the cross-sectional shape of the tow prepreg P is gradually flattened.

Each guiding roller12aof this embodiment guides a plurality of (five) tow prepreg P fed from the feeding mechanism11in a lump. However, the guiding roller12amay be configured by a divided roller that individually guides the plurality of tow prepregs P. In addition, the guiding mechanism12of this embodiment has seven guiding rollers12a, but the number of guiding rollers12ais not limited thereto.

The winding mechanism13includes a driving portion13a(rotating motor) that rotates the liner2around the Ax-axis and a band feeding head13bthat feeds the band B to the rotating liner2.

The band feeding head13barranges a plurality of (five) tow prepregs P flattened by the guiding mechanism12in the widthwise direction and integrates them. As a result, the band feeding head13bforms a band B which is a band-shaped tow prepreg P.

The band feeding head13bis composed of a pair of compressing rollers13b1and13b1arranged in parallel with a predetermined clearance therebetween. The plurality of (five) tow prepregs P arranged side by side on the upstream side of the band feeding head13bare press-formed into the widened band B when passing between the pair of compressing rollers13b1and13bl.

The band feeding head13bcan move in the Ax-axis direction of the liner2while feeding the band B to the rotating liner2. Specifically, the band feeding head13bmoves in the Ax-axis direction in accordance with the rotation of the liner2so that the unit layer7(seeFIG.2) is formed on the outer circumferential side of the liner2. The moving means of the band feeding head13bof this embodiment is a linear actuator13csuch as a pneumatic cylinder or a linear motor, but is not limited thereto.

The band feeding head13bis configured to adjust the tension of the band B to be fed to the liner2. Specifically, the band feeding head13badjusts a load applied to the tow prepreg P in a direction intersecting the travel direction of the tow prepreg P. The tension adjustment means of the band B of this embodiment is a spacing adjustment actuator13cprovided between the linear actuator13band the band feeding head13d. The spacing adjustment actuator13dmay be a rack-and-pinion mechanism or a pneumatic cylinder driven by a rotating motor, but is not limited thereto.

Further, the spacing adjustment actuator13dof this embodiment displaces the band feeding head13bbased on the detected tension of the tow prepreg P or the band B so that the detected tension becomes a preset target tension. The means for detecting the tension of the tow prepreg P or the band B is a sensor for detecting the reaction force that the band feeding head13breceives from the tow prepreg P or the band B, but is not limited thereto.

The displacement control means of the band feeding head13bincludes a program for instructing the spacing adjustment actuator13dto set the detected tension of the tow prepreg P or the band B to the target tension, a read only memory (ROM) for storing the program, a random access memory (RAM) for reading and developing the program stored in the ROM, and a central processing unit (CPU) for executing the developed program and outputting an instruction to the spacing adjustment actuator13d.

Next, a method for manufacturing the high pressure tank1of this embodiment will be described.

The method according to this embodiment includes a winding process of winding the band B (seeFIG.3) in which the tow prepreg P (seeFIG.3) is formed in a band shape on the outer surface of the liner2(seeFIG.3), and a reinforcing layer forming process of forming the reinforcing layer4(seeFIG.2) by curing the curable resin included in the tow prepreg P wound around the outer surface of the liner2.

Here, the method according to this embodiment will be described in detail by taking as an example a method of winding the band B (seeFIG.3) around the body portion5(seeFIG.3) of the liner2(seeFIG.3) by a hoop winding.

FIG.4is an explanatory diagram of the hoop winding of band B around the liner2.

As shown inFIG.4, the hoop winding is a method in which the band B is wound in a hoop shape (in a ring shape) around the body portion5of the liner2. That is, the hoop winding is set so that an angle θ1 formed by the extended direction D of the band B with respect to the Ax-axis direction is close to 90 degrees so that the band B is parallel to the Ax-axis direction. As a result, the band B forms a unit layer7(seeFIG.2) having a thickness substantially equal to the thickness of the band B on the outer circumference of the body portion5of the liner2.

FIG.5is an explanatory diagram of the winding process of band B by the hoop winding.FIG.5is a partially enlarged sectional view of a portion V inFIG.1. In addition, inFIG.5, tensions Te1, Te2, Tg1, and Ts2of the band B are indicated by white arrows pointing downward on the paper for convenience of drawing.

As shown inFIG.5, in this winding process, a plurality of unit layers7are formed on the outer circumference of the body portion5of the liner2. As shown inFIG.3, in the hoop winding, the band feeding head13bis reciprocated with respect to the rotating liner2by a distance corresponding to the body portion5of the liner2, thereby forming the unit layer7. Specifically, the odd-numbered unit layer7(seeFIG.5) is formed in the forward path of the band feeding head13b(seeFIG.3), and the even-numbered unit layer7(seeFIG.5) is formed in the backward path. Thus, as shown inFIG.5, a first unit layer7a, a second unit layer7b, and a third unit layer7care formed on the outer circumference of the body portion5in order from the liner2side. In addition, the unit layers are laminated on the top surface of the third unit layer7c(now shown).

In addition, such a winding process is performed so that the tension of a band B (fiber bundle) at both end portions5eof the body portion5of the liner2(inFIG.5, only the end portion5eon the left side of the paper surface is shown, and the end portion on the right side of the paper surface is omitted) is lower than the tension of the fiber bundle at a general portion5gof the body portion5.

In this embodiment, the end portion5eof the body portion5is a portion adjacent to the dome portion6. In addition, the general portion5gof the body portion5is a portion that occupies almost most of the body portion5defined between both end portions5eof the body portion5.

In addition, the plurality of unit layers7a,7b,7c, . . . laminated on the outer circumference of the body portion5of the liner2are independent of each other. The tensions of the bands B (fiber bundles) at the both end portions5eare reduced to be lower than the tension of the band B (fiber bundle) at the general portion5g.

That is, in the first unit layer7ashown inFIG.5, a tension Te1of the band B (fiber bundle) wound around the end portion5eis reduced to be lower than a tension Tg1of the band B (fiber bundle) would around the general portion5g. In addition, in the second unit layer7bshown inFIG.5, a tension Te2of the band B (fiber bundle) wound around the end portion5eindependently of the first unit layer7ais reduced to be lower than a tension Tg2of the band B (fiber bundle) wound around the general portion5g.

As shown inFIG.5, at least a part of the band B (fiber bundle) may be wound around the end portion5eof the body portion5. That is, the band B (fiber bundle) may be wound around a connecting portion2abetween the body portion5and the dome portion6. In addition, the loop-wound band B (fiber bundle) may be wound around the end portion5eso as not to extend toward the dome portion6(not shown).

In addition, as shown inFIG.5, the tensions of the bands B (fiber bundles) of the plurality of unit layers7a,7b,7c, . . . laminated on the general portion5gof the body portion5in the radial direction are preferably reduced toward the outer circumferential side.

That is, in the configuration shown inFIG.5, the tension Tg2of the second unit layer7bis preferably reduced to be lower than the tension Tg1of the first unit layer7a(Tg1>Tg2). In addition, the tension Te1of the end portion5eof the first unit layer7ais preferably reduced to be lower than the tension Tg2of the general portion5gof the second unit layer7b(Te1<Tg2).

Note that the plurality of unit layers7a,7b,7c, . . . are independent of each other. The tensions of the bands B (fiber bundles) at the both end portions5eare reduced to be lower than the tension of the band B (fiber bundle) at the general portion5g. Therefore, the configuration which meets the conditions of Tg1>Tg2and Te1>Tg2is acceptable.

In addition, the tensions of the bands B (fiber bundles) of the plurality of unit layers7a,7b,7c, . . . laminated on the end portion5eof the body portion5in the radial direction are preferably reduced toward the outer circumferential side.

That is, in the configuration shown inFIG.5, the tension Te2of the second unit layer7bis preferably reduced to be lower than the tension Te1of the first unit layer7a(Te1>Te2).

As shown inFIG.4, in the method of this embodiment, after the band B (seeFIG.3) is wound around the body portion5of the liner2by the hoop winding, the band B (seeFIG.3) is further wound around the liner2(seeFIG.3) by the helical winding. Specifically, in this method, the band B is wound by a high helical winding around the band B (seeFIG.4) wound around the body portion5by the hoop winding, and the band B is further wound by a low helical winding around the band B wound by the high helical winding.

FIG.6is an explanatory diagram of the high helical winding of the band B (seeFIG.3).FIG.7is an explanatory diagram of the low helical winding of the band B (seeFIG.3).

As shown inFIG.6, the high helical winding is set so that an angle θ2 formed by the extended direction D of the band B (seeFIG.3) with respect to the Ax-axis direction is approximately 75 degrees. As a result, the band B is wound around the body portion5of the liner2on which the hoop winding is performed and the peripheral portion of the dome portion6adjacent to the body portion5.

As shown inFIG.7, the low helical winding is set so that an angle θ3 formed by the extended direction D of the band B (seeFIG.3) with respect to the Ax-axis direction is approximately 10 degrees. As a result, the band B is wound around the entire region from the body portion5to the dome portion6of the liner2around which the hoop winding and the high helical winding have been performed.

In the method according to this embodiment, the tension of the band B (seeFIG.3) of the high helical winding and the tension of the band B (seeFIG.3) of the low helical winding are set to be substantially the same as the tension of the outermost band B (seeFIG.3) wound around the general portion5g(seeFIG.5) by the hoop-winding. However, the tension of the band B (seeFIG.3) of the high helical winding and the tension of the band B (seeFIG.3) of the low helical winding can be set to be reduced toward the outer peripheral side of the reinforcing layer4(seeFIG.1).

In the reinforcing layer forming process, the liner2(seeFIG.3) which has completed the winding process is removed from the winding mechanism13(seeFIG.3) and is heated at a predetermined temperature in a heating furnace (not shown).

As a result, the curable resin contained in the band B (seeFIG.3) wound around the liner2is cured. In the process of curing the curable resin, the plurality of unit layers7(seeFIG.5) laminated on each other are integrated and are in close contact with the outer surface of the liner2. Thus, the reinforcing layer4(seeFIG.1) is formed, and a series of manufacturing processes of the high pressure tank1is completed.

Effects

Next, the operation and effect of the method for manufacturing the high pressure tank1of this embodiment will be described.

In the method according to this embodiment, the winding process of the band B (fiber bundle) around the liner2is performed so that the tension of the bands B (fiber bundles) at the both end portions5e(seeFIG.5) of the body portion5is reduced to be lower than the tension of the band B (fiber bundle) at the general portion5g(seeFIG.5) of the body portion5.

According to this method, when the band B (fiber bundle) is wound and overlapped on the entire body portion5along the Ax-axis direction of the body portion5of the liner2, the winding of the band B (fiber bundle) can be more reliably prevented from collapsing at the both end portions5eof the body portion5.

Thus, the method according to this embodiment can more reliably increase the breaking strength of the reinforcing layer4as compared with the prior art method (for example, see Patent Literature 1).

In addition, the winding process of this method is performed by the hoop winding of the band B (fiber bundle) around the body portion5of the liner2.

According to this method, the tensions of the band B (fiber bundle) at both end portions5e(seeFIG.5) can be more reliably reduced.

In addition, in this method, the unit layer7(seeFIG.2) which forms the reinforcing layer4(seeFIG.2) is formed by arranging the band-shaped band B (fiber bundle) in parallel in the Ax-axis direction of the liner2.

According to this method, the tension of the band B (fiber bundle) at each of the unit layers7can be more reliably controlled. Thus, the difference between the tension of the band B (fiber bundle) at the general portion5gand the tension of the band B (fiber bundle) at the end portion5ecan be equalized.

In addition, in this method, the plurality of unit layers7(seeFIG.5) are independent of each other. The tension of the bands B (fiber bundles) at the both end portions5e(seeFIG.5) of the body portion5is reduced to be lower than the tension of the band B (fiber bundle) at the general portion5g(seeFIG.5) of the body portion5.

According to this method, the winding of the band B (fiber bundle) can be more reliably prevented from collapsing at the both end portions5e(seeFIG.5) for each of the unit layers7(seeFIG.5).

In addition, the tensions of the bands B (fiber bundles) of the plurality of unit layers7laminated on the end portion5eof the body portion5in the radial direction are preferably reduced toward the outer circumferential side.

According to this method, the winding of the band B (fiber bundle) can be more reliably prevented from collapsing at the both end portions5e(seeFIG.5).

In addition, in this method, the tensions of the bands B (fiber bundles) of the plurality of unit layers7(seeFIG.5) laminated in the radial direction of the general portion5gare preferably reduced toward the outer circumferential side.

According to this method, the tension of the outer layer side band B (fiber bundle) wound around the liner2prevents the inner layer side band B (fiber bundle) from loosening, that is, the so-called bandage effect. According to this method, the breaking strength of the reinforcing layer4can be more reliably increased.

Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments and can be implemented in various forms.