Carbon fiber reinforced resin cylinder for propeller shaft

Abstract

Provided is a carbon fiber-reinforced resin cylinder for a propeller shaft, which has high flexural rigidity and high torsional strength. A fiber-reinforced resin tube body (30A), which is a cylinder made of a carbon fiber-reinforced resin for a propeller shaft, comprises: a first carbon fiber-reinforced resin layer having a first carbon fiber, and a second carbon fiber-reinforced resin layer having a second carbon fiber-reinforced resin layer having a second carbon fiber-reinforced resin layer having a second carbon fiber-reinforced resin; and a second carbon fiber-reinforced resin layer that has second carbon fibers that have a higher strength and a lower elastic modulus than the first carbon fiber-reinforced resin layer, the first carbon fibers being disposed so as to extend in the longitudinal direction of the cylinder.

Description

Technical Field

[0001] The present invention relates to a carbon-fiber-reinforced resin cylinder for propeller shafts used, for example, as a power transmission shaft of a vehicle. Background Art

[0002] As a propeller shaft for automobiles, a propeller shaft that is divided into two parts front and back and has an intermediate bearing near the center in the front-to-back direction is generally used. Among such propeller shafts, a structure is known that changes the two-part structure to an integrated structure for the purpose of energy saving and achieves lightweight by removing the intermediate bearing. In this case, in order to increase the bending main resonance point of the propeller shaft, it is necessary to increase the diameter of the cylinder (steel pipe).

[0003] Since the transmission shaft transmits high power and rotates at high speed, it is necessary to improve the torsional strength and bending rigidity. In particular, the bending rigidity can be improved by increasing the diameter of the transmission shaft. However, if the diameter is increased while the transmission shaft is made of iron, the mass of the transmission shaft increases. Therefore, a technology for suppressing the increase in weight by making the transmission shaft made of carbon fiber reinforced resin is known (for example, refer to Patent Document 1).

[0004] The carbon fiber reinforced resin shaft component is formed by molding using a filament winding (FW: filament winding) process. In this process, the shaft component is molded by winding carbon fibers impregnated with resin one by one around a core component and heating. In the case of a carbon fiber reinforced resin shaft component, in order to improve torsional strength, it is effective to wind the carbon fibers obliquely relative to the rotation axis. In addition, in order to improve bending rigidity, it is known to use highly elastic carbon fibers (for example, refer to Patent Document 2). Prior art literature Patent Literature

[0005] Patent Document 1: Japanese Patent Publication No. 2001-153126 Patent Document 2: Japanese Patent Publication No. 61-487 Summary of the invention [Technical problem to be solved by the invention]

[0006] As highly elastic carbon fibers, there are carbon fibers made from polyacrylonitrile materials called PAN, but there is a problem of increased cost. In addition, in order to improve the bending rigidity, although it is effective to arrange the carbon fibers parallel to the rotation axis, it is necessary to arrange the carbon fibers densely in the circumferential direction, which cannot be achieved by the filament winding process method.

[0007] On the other hand, a sheet winding method is known in which a prepreg (pre-preg) as an intermediate material in the form of a sheet, which is formed by impregnating carbon fibers with a matrix resin, is arranged on a mandrel. Using this method, if the prepreg is arranged on a mandrel so that the carbon fibers are directed in the direction of the rotation axis, the bending rigidity can be improved. However, since the material cost is high and the production efficiency is reduced by stacking the sheets one by one, it is limited to the propeller shaft for racing cars in products such as propeller shafts.

[0008] In view of the above circumstances, an object of the present invention is to provide a carbon fiber reinforced resin cylinder for a propeller shaft having high bending rigidity and high torsional strength without causing a cost increase. [Technical solutions for solving technical problems]

[0009] According to the present invention, a carbon fiber reinforced resin cylinder for a transmission shaft is provided, which includes a first carbon fiber reinforced resin layer and a second carbon fiber reinforced resin layer, wherein the first carbon fiber reinforced resin layer has a first carbon fiber; the second carbon fiber reinforced resin layer has a second carbon fiber, and has a greater strength and a smaller elastic modulus than the first carbon fiber reinforced resin layer, and the first carbon fiber is configured to extend along the length direction of the cylinder. [Effects of the invention]

[0010] According to the present invention, it is possible to provide a carbon fiber reinforced resin cylindrical body for a propeller shaft which has high bending rigidity and high torsional strength without causing a cost increase. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a cross-sectional view schematically showing a mandrel according to the first embodiment of the present invention. Figure 2 It is a diagram schematically showing a power transmission shaft manufactured using the spindle according to the first embodiment of the present invention. Figure 3 It is a cross-sectional view schematically showing a power transmission shaft according to the first embodiment of the present invention. Figure 4 It is a schematic diagram for explaining the method for manufacturing a power transmission shaft according to the first embodiment of the present invention, and is a diagram schematically showing a first carbon fiber layer. Figure 5 It is a schematic diagram for explaining the method for manufacturing the power transmission shaft according to the first embodiment of the present invention, and is a diagram schematically showing a second carbon fiber layer. Figure 6 It is a schematic diagram for explaining the method for manufacturing the power transmission shaft according to the first embodiment of the present invention, and is a diagram schematically showing a third carbon fiber layer. Figure 7 This is a flowchart for explaining the method for manufacturing the power transmission shaft according to the first embodiment of the present invention. Figure 8 It is a schematic diagram for explaining the method for manufacturing the power transmission shaft according to the first embodiment of the present invention. Fig. 9 This is a diagram schematically showing a first carbon fiber layer of a fiber-reinforced resin pipe body according to a second embodiment of the present invention. Fig.10 This is a diagram schematically showing a first carbon fiber layer of a fiber-reinforced resin pipe body according to a second embodiment of the present invention. Fig.11 It is a schematic diagram for explaining a method for manufacturing a power transmission shaft according to a third embodiment of the present invention, and is a diagram schematically showing a first carbon fiber layer. Fig.12 It is a schematic diagram for explaining a method for manufacturing a power transmission shaft according to a third embodiment of the present invention, and is a diagram schematically showing a second carbon fiber layer. Fig.13 It is a schematic diagram for explaining a method for manufacturing a power transmission shaft according to a third embodiment of the present invention, and is a diagram schematically showing a fourth carbon fiber layer. Fig.14 It is a schematic diagram for explaining a method for manufacturing a power transmission shaft according to a third embodiment of the present invention, and is a diagram schematically showing a third carbon fiber layer. Fig.15 This is a flowchart for explaining a method for manufacturing a power transmission shaft according to a third embodiment of the present invention. DETAILED DESCRIPTION

[0012] Taking the case of manufacturing a propeller shaft of a vehicle as an example of a fiber-reinforced resin pipe body using carbon fiber reinforced plastic as an example, the embodiment of the present invention is described in detail with reference to the accompanying drawings. In the following description, the same structural elements are marked with the same figure numbers, and repeated descriptions are omitted. In addition, the referenced drawings are deformed for easy understanding.

[0013] <First Embodiment> like Figure 1As shown, the mandrel 1 involved in the first embodiment is used to manufacture a fiber reinforced resin pipe body 30A (see Figure 2 ), having a spindle body 10 and an embedded component 20.

[0014] 《Heart axis body》 The mandrel body 10 is a cylindrical resin component. In the present embodiment, the mandrel body 10 is removed from the inside of the fiber reinforced resin tube body 30A, but it can also remain in the fiber reinforced resin tube body 30A and act as the core material of the fiber reinforced resin tube body 30A. The mandrel body 10 can use a material that can withstand the heating when the resin of the fiber reinforced resin tube body 30A is cured. As examples of such materials, PP (polypropylene resin), PET (polyethylene terephthalate resin), SMP (shape memory polymer), etc. can be listed. The mandrel body 10 integrally has a large diameter portion 11 in the axial middle portion, a step portion 12 and a small diameter portion 13 formed at one axial end, and a tapered portion 14 and a small diameter portion 15 formed at the other axial end. In the present embodiment, a protrusion 16 having a smaller diameter than the small diameter portion 15 is formed at the other axial end of the small diameter portion 15. The protrusion 16 is a portion for externally embedding the second metal component 50. In addition, the mandrel body 10 can be a metal component. Furthermore, the mandrel body 10 as a metal member may be configured to be pulled out from the fiber-reinforced resin tube 30A after the fiber-reinforced resin tube 30A is molded.

[0015] 《Built-in components》 The inner member 20 is a cylindrical metal member that is embedded in the other axial end portion of the mandrel body 10, that is, the small diameter portion 13. The inner member 20 prevents the small diameter portion 13 from deforming radially inward and is formed with a pressure fluid F (see Figure 8 ) (for example, pressurized air) flow path 20a. In the present embodiment, the pressurized fluid F is used to pressurize the inside of the mandrel body 10 in the molding device 100 to expand it. In addition, the pressurized fluid F is also a heating fluid used for heating so as to solidify the thermosetting resin (resin 34 described later) arranged on the outer peripheral surface of the mandrel body 10 in the molding device 100 described later. In addition, in the case where the mandrel body 10 is a metal component, the embedded component 20 can be omitted by being formed integrally with the mandrel body 10.

[0016] <Power transmission shaft> like Figure 2 and Figure 3 As shown, using spindle 1 (refer to Figure 1) is a shaft extending in the front-rear direction in a vehicle and transmitting the power generated by a power source as a rotation around an axis. The power transmission shaft 2 includes a fiber reinforced resin pipe body 30A, a first metal component 40, a second metal component 50, and universal joints 3 and 4. The fiber reinforced resin pipe body 30A is a carbon fiber reinforced resin cylinder for a transmission shaft that transmits the transmission force by rotating around the axis of the fiber reinforced resin pipe body 30A.

[0017] <Fiber-reinforced resin pipe body> The fiber-reinforced resin tube body 30A is a resin-containing fiber layer formed in a tubular shape along the outer peripheral surface of the mandrel body 10. The fiber-reinforced resin tube body 30A is formed along the outer peripheral surfaces of the large diameter portion 11, the tapered portion 14, and the small diameter portion 15 of the mandrel body 10, the other axial end portion of the first metal component 40, and the axial end portion of the second metal component 50. Figures 4 to 6 As shown, the fiber-reinforced resin tube body 30A has, as a carbon fiber layer, a first carbon fiber layer 31, a second carbon fiber layer 32, and a third carbon fiber layer 33 in order from the radial inner side (the side of the spindle body 10). The carbon fibers (second carbon fibers) constituting the second carbon fiber layer 32 and the third carbon fiber layer 33 are stronger and have a smaller elastic modulus than the carbon fibers (first carbon fibers) constituting the first carbon fiber layer 31. Figures 4 to 6 , only a portion of the carbon fiber layers 31, 32, and 33 are shown. In addition, the outer peripheral surface of one axial end portion of the first metal component 40 (the end portion located on the opposite side of the mandrel body 10) and the outer peripheral surface of the other axial end portion of the second metal component 50 (the end portion located on the opposite side of the mandrel body 10) are not covered by the fiber-reinforced resin tube body 30A and protrude from the fiber-reinforced resin tube body 30A.

[0018] 《First Carbon Fiber Layer》 like Figure 4 As shown in FIG. 1 , the first carbon fiber layer 31 is composed of a plurality of carbon fibers arranged on the outer peripheral surface of the mandrel body 10 and the like so as to cover the mandrel body 10. More specifically, a carbon fiber aggregate is formed by winding a plurality of carbon fibers into a strip or bundle shape, and the first carbon fiber layer 31 is formed by arranging the plurality of carbon fiber aggregates with a phase change. The carbon fibers of the first carbon fiber layer 31 are extended parallel to the axial direction of the mandrel body 10. That is, with respect to the first carbon fiber layer 31, the orientation angle (orientation angle) of the carbon fibers relative to the axis X of the mandrel body 10 is 0°.

[0019] The carbon fibers (first carbon fibers) of the first carbon fiber layer 31 are pitch-based carbon fibers. The first carbon fiber layer 31 is impregnated with a resin 34 and cured to form a first carbon fiber reinforced resin layer. The first carbon fiber reinforced resin layer composed of the first carbon fiber layer 31 and the resin 34 is a straight reinforced layer in which the first carbon fibers are arranged parallel to the length direction of the cylinder (fiber reinforced resin tube body 30A). The first carbon fiber layer 31 (and the fourth carbon fiber layer 35 described later) contribute to the inherent value (natural vibration frequency) and bending rigidity of the fiber reinforced resin tube body 30A.

[0020] In the first carbon fiber layer 31 (and the fourth carbon fiber layer 35 described later), a plurality of first carbon fibers are arranged at equal intervals in the circumferential direction. The intervals between adjacent first carbon fibers can be appropriately set. The fiber-reinforced resin tube body 30A can increase the number of first carbon fibers and improve the bending rigidity of the fiber-reinforced resin tube body 30A by setting the intervals between adjacent first carbon fibers in the circumferential direction to be smaller. In addition, the fiber-reinforced resin tube body 30A can reduce the number of first carbon fibers and reduce the cost of the fiber-reinforced resin tube body 30A by setting the intervals between adjacent first carbon fibers in the circumferential direction to be larger.

[0021] 《Second carbon fiber layer》 like Figure 5 As shown, the second carbon fiber layer 32 is arranged radially outside the first carbon fiber layer 31, and is composed of a plurality of carbon fibers arranged in a manner covering the first carbon fiber layer 31. More specifically, a carbon fiber aggregate is formed by winding a plurality of carbon fibers into a strip or bundle shape, and the second carbon fiber layer 32 is formed by arranging the plurality of carbon fiber aggregates in a phase-changing manner. The carbon fibers of the second carbon fiber layer 32 are wound one or more times in a manner inclined at 45° relative to the axial direction of the mandrel body 10, and are arranged to extend in a spiral shape relative to the axial direction of the mandrel body 10. That is, with respect to the second carbon fiber layer 32, the orientation angle of the carbon fibers relative to the axis X of the mandrel body 10 is 45°.

[0022] The carbon fibers (second carbon fibers) of the second carbon fiber layer 32 are polyacrylonitrile-based carbon fibers. The second carbon fiber layer 32 is impregnated with a resin 34 and cured to form a second carbon fiber reinforced resin layer. The second carbon fiber reinforced resin layer formed by the second carbon fiber layer 32 and the resin 34 is a first bias reinforced layer (bias reinforced layer) in which the second carbon fibers have an orientation angle relative to the length direction of the barrel (fiber reinforced resin tube body 30A). The second carbon fiber layer 32 contributes to the torsional strength of the fiber reinforced resin tube body 30A.

[0023] 《Third Carbon Fiber Layer》 like Figure 6 As shown, the third carbon fiber layer 33 is arranged radially outside the second carbon fiber layer 32, and is composed of a plurality of carbon fibers arranged in a manner covering the second carbon fiber layer 32. More specifically, a carbon fiber aggregate is formed by winding a plurality of carbon fibers into a strip or bundle shape, and the third carbon fiber layer 33 is formed by arranging the plurality of carbon fiber aggregates in a phase-changing manner. The carbon fibers of the third carbon fiber layer 33 are wound one or more times in a manner inclined at -45° relative to the axial direction of the mandrel body 10, and are arranged to extend in a spiral shape relative to the axial direction of the mandrel body 10. That is, with respect to the third carbon fiber layer 33, the orientation angle of the carbon fibers relative to the axis X of the mandrel body 10 is -45°.

[0024] The carbon fibers (second carbon fibers) of the third carbon fiber layer 33 are polyacrylonitrile-based carbon fibers. The third carbon fiber layer 33 is impregnated with resin 34 and cured to form a second carbon fiber reinforced resin layer. The second carbon fiber reinforced resin layer formed by the third carbon fiber layer 33 and the resin 34 is a second oblique reinforcement layer in which the second carbon fibers have an orientation angle opposite to the first oblique reinforcement layer with respect to the length direction of the cylinder (fiber reinforced resin tube body 30A). The third carbon fiber layer 33 contributes to the torsional strength of the fiber reinforced resin tube body 30A.

[0025] The first carbon fiber of the first carbon fiber layer 31 (and the fourth carbon fiber layer 35 described later) has a lower strength and a higher elastic modulus than the second carbon fiber, and for example, the tensile elastic modulus is preferably set to 420 GPa or more and the tensile strength is preferably set to 2600 MPa or more. In addition, the second carbon fiber of the second carbon fiber layer 32 and the third carbon fiber layer 33 has a higher strength and a lower elastic modulus than the first carbon fiber, and for example, the tensile strength is preferably set to 3500 to 7000 MPa and the tensile elastic modulus is preferably set to 230 to 324 GPa.

[0026] like Figure 2 and Figure 3 As shown, the fiber reinforced resin pipe body 30A has a tapered portion 30b formed on one axial end side, which is reduced in diameter from the large diameter portion 30a on the axial center side to the small diameter portion 30c on one axial end. The large diameter portion 30a is a main body portion in a shape along the outer peripheral surface of the large diameter portion 11 of the mandrel body 10. The tapered portion 30b is in a shape along the outer peripheral surface of the tapered portion 14 of the mandrel body 10. The small diameter portion 30c is an end portion in a shape along the outer peripheral surface of the small diameter portion 15 of the mandrel body 10 and a part of the second metal component 50.

[0027] <First Metal Part> The first metal component 40 is a component in a substantially cylindrical shape. Figure 5 As shown in FIGS. 1 and 1 , in the middle stage of manufacturing, the first metal member 40 is fitted (outer-fitted) to the mandrel body 10 .

[0028] The first metal component 40 is a component of the universal joint (yoke assembly) 3 of the power transmission shaft 2. The universal joint 3 is formed by assembling a cross shaft, a needle bearing, and a yoke body with respect to the first metal component 40.

[0029] <Second Metal Member> The second metal component 50 is a component (shaft) having a substantially cylindrical shape. Figure 5 As shown in FIGS. 1 and 1 , the second metal member 50 is fitted (outer-fitted) to the mandrel body 10 during the manufacturing process.

[0030] like Figure 1 As shown, a bottomed hole 50 a into which the protrusion 16 of the mandrel body 10 can be inserted is formed at one axial end portion of the second metal member 50 .

[0031] The second metal member 50 is a part of the universal joint 4 (plunge universal joint assembly) of the power transmission shaft 2. The universal joint 4 is formed by assembling a shield and a plunge universal joint body to the second metal member 50.

[0032] <Manufacturing method> Next, use Figure 7 The flowchart of the present invention illustrates a method for manufacturing a power transmission shaft 2 using the spindle 1 involved in the first embodiment of the present invention. The method for manufacturing the power transmission shaft 2 includes a spindle body forming process (step S1), an embedded component setting process (step S2) performed after the spindle body forming process, a first connection process (step S3) performed after the embedded component setting process, and a second connection process (step S4) performed after the first connection process. In addition, the method for manufacturing the power transmission shaft 2 includes a fiber setting process (steps S5A to S5C) performed after the second connection process, and a mold setting process (step S6) performed after the fiber setting process. In addition, the method for manufacturing the power transmission shaft 2 includes an expansion process (step S7) performed after the mold setting process, and a molding process (step S8) performed after the expansion process. In addition, the method for manufacturing the power transmission shaft 2 includes a removal process (step S9) performed after the molding process and a universal joint assembly process (step S10) performed after the removal process.

[0033] Step S1 is to form a Figure 1 The steps of manufacturing the resin mandrel body 10 are shown.

[0034] Following step S1, in step S2, the embedded component 20 is pressed into the small diameter portion 13 of the mandrel body 10 and embedded therein. During the press-in, a lubricant may be applied between the outer peripheral surface of the embedded component 20 and the outer peripheral surface of the small diameter portion 13. In addition, step S2 only needs to be performed before step S8.

[0035] Following step S2, in step S3, a first metal member 40 is provided at one axial end of the mandrel body 10. In step S3, the first metal member 40 is fitted (externally fitted) to the step portion 12 of the mandrel body 10.

[0036] Following step S3, in step S4, a second metal component 50 is provided at the other end portion in the axial direction of the mandrel body 10. In step S4, the second metal component 50 is fitted (embedded) in the protrusion 16 of the mandrel body 10. Here, the order of steps S3 and S4 can be changed as appropriate, and step S4 can be performed first or simultaneously.

[0037] Following step S4, in step S5A, if Figure 4 As shown in FIG. 1 , a first carbon fiber layer 31 is formed on the outer peripheral surfaces of the mandrel body 10, the first metal component 40 and the second metal component 50. Next, step S5A is performed. In step S5B, as shown in FIG. Figure 5 As shown in FIG. 1 , a second carbon fiber layer 32 is formed on the outer peripheral surface of the first carbon fiber layer 31 of the mandrel body 10, the first metal component 40 and the second metal component 50. Next, step S5B is performed. In step S5C, as shown in FIG. Figure 6 As shown, the third carbon fiber layer 33 is formed on the outer peripheral surface of the second carbon fiber layer 32 of the mandrel body 10, the first metal component 40 and the second metal component 50. In steps S5A to S5C, the carbon fiber layers 31 to 33 are formed in such a manner that individual fibers are not arranged at the ends of the first metal component 40 and the second metal component 50 on the opposite side to the mandrel 10 in the axial direction.

[0038] In steps S5A to S5C, the carbon fiber layers 31 to 33 are so-called raw silk, not resin-impregnated fibers. In addition, the carbon fiber layers 31 to 33 are simultaneously arranged on the outer peripheral surfaces of the other end portions in the axial direction of the mandrel body 10, the first metal member 40, and the second metal member 50 by a multi-feed filament winding method. The carbon fiber layers 31 to 33 fed by the multi-feed filament winding method have a so-called non-crimp structure in which they are not woven together but are independent layers.

[0039] In steps S5A to S5C, the carbon fiber layers 31 to 33 are arranged on the outer peripheral surface of the mandrel body 10 or the like by a device not shown in the figure. The device can appropriately set and change the orientation angle of the carbon fiber layers 31 to 33. In addition, the carbon fiber layers 31 to 33 may be configured so that they are arranged in an integral cylindrical shape by the device and then arranged on the outer peripheral surface of the mandrel body 10 or the like.

[0040] In the (single-feed) filament winding method, a jig having a plurality of radially extending pins is disposed at both ends of a mandrel, and a carbon fiber is repeatedly wound around the outer peripheral surface of the mandrel while being locked by the pins, thereby forming a fiber layer. Therefore, in the (single-feed) filament winding method, it may not be possible to properly hold the carbon fiber layer 31 that is not wound around the mandrel body 10 and needs to be arranged in less than one turn on the outer peripheral surface of the mandrel body 10 and the like.

[0041] In contrast, in the multi-feed filament winding method, each fiber layer in the carbon fiber layers 31 to 33 is arranged as a cylindrical layer composed of a plurality of carbon fibers, and the mandrel body 10 or the like is inserted into the cylindrical layer (or the cylindrical layer is externally embedded on the mandrel body 10 or the like). In addition, in the multi-feed filament winding method, the carbon fiber layers 31 to 33 can be formed simultaneously. Therefore, in the multi-feed filament winding method, the carbon fiber layer 31 that is not wound on the mandrel body 10 or the like and needs to be arranged as less than one turn can be appropriately maintained on the outer peripheral surface of the mandrel body 10 or the like by the carbon fiber layers 32 and 33 on the radially outer side.

[0042] Following step S5C, in step S6, if Figure 8 As shown, an assembly of the mandrel 1 , the first metal member 40 , the second metal member 50 , and the carbon fiber layers 31 to 33 is placed in a molding device (mold) 100 .

[0043] Following step S6, in step S7, the mandrel body 10 is expanded. Figure 8 As shown, in the molding device 100 of the first embodiment, a communication passage 104 is provided in a manner that communicates with the inner side of the mandrel body 10 via the flow path 20a. In step S7, the hollow portion of the mandrel body 10 is filled with a pressurized fluid F (for example, pressurized air at 140°C or above) via the communication passage 104 connected to a supply device (not shown). The mandrel body 10 heated by the high-temperature pressurized fluid F softens when the temperature becomes lower than the temperature at which the resin 34 is solidified (i.e., the phase change temperature is 80°C), and is pressurized from the inside by the pressurized fluid F, and expands and deforms in a manner along the inner peripheral surface of the molding device 100. By the pressurization, the mandrel body 10 can be prevented from being deformed in the diameter reduction direction due to the filled resin 34. In addition, by the pressurization, the filling amount of the resin 34 can be suppressed, and the weight increase of the fiber reinforced resin tube body 30A as a finished product can be prevented.

[0044] Next, in step S7, resin 34 is supplied to the molding device 100. Accordingly, the resin 34 is impregnated in the carbon fiber layers 31 to 33 arranged on the outer peripheral surface of the mandrel body 10. Furthermore, by applying heat to the molding device 100, the resin 34 is cured, thereby forming the fiber-reinforced resin tube body 30A, and the fiber-reinforced resin tube body 30A, the first metal component 40 and the second metal component 50 are integrally molded (step S8, molding process). The resin 44 is, for example, a thermosetting resin. In this embodiment, the mold of the molding device 100 is divided into a plurality of parts. In step S9, the assembly is heated and a mold closing operation of closing the mold of the molding device 100 is performed, and a mold clamping operation of applying pressure to the closed mold is further performed, thereby increasing the pressure in the mold, thereby promoting the curing of the resin 34. In addition, in this embodiment, the structure in which the mold is divided into a plurality of parts is described, so the mold closing operation and the mold clamping operation are performed, but the mold clamping operation is not necessary. In addition, when the mold is not divided into a plurality of parts, the mold closing operation and the mold clamping operation are not necessary. In the molding device 100, a space (resin reservoir 102) is formed on the outlet side of the gate 101 for introducing the molten resin 34. The resin 34 introduced into the molding device 100 is stored in the resin reservoir 102 located on the side of the other axial end of the carbon fiber layers 31 to 33. The resin 34 stored in the resin reservoir 102 is moved along the axial direction of the mandrel body 10 by vacuum suction from the suction port 103, which is formed on the side opposite to the gate 101 in the arrangement direction of the carbon fiber layers 31 to 33 (the outer peripheral surface side of one axial end of the carbon fiber layers 31 to 33), and is impregnated in the carbon fiber layers 31 to 33. In a state where the resin 34 is impregnated in the carbon fiber layers 31 to 33, the molding device 100 is heated and pressure is further applied to the molding device 100, thereby forming the fiber-reinforced resin tube 40A.

[0045] Following step S8, in step S9, the molded assembly, ie, the intermediate body, is taken out from the molding device 100. Following step S9, in step S10, the universal joint 3 is mounted on the first metal component 40 of the intermediate body and the universal joint 4 is mounted on the second metal component 50.

[0046] In addition, it is conceivable to perform a mandrel extraction process between step S9 and step S10. The mandrel extraction process is a process of extracting the mandrel 1 from the end opening side of the first metal component 40 to the outside of the fiber-reinforced resin tube body 30A. At this time, the mandrel 1 is extracted from the inside of the fiber-reinforced resin tube body 30A by, for example, deformation, melting, decomposition, destruction, or elution according to a method corresponding to the material used. In this way, the weight reduction of the power transmission shaft 2 is achieved.

[0047] In addition, when the mandrel 1 is deformed and removed from the end opening side of the first metal component 40, for example, the following method can be used: the hollow portion of the mandrel body 10 is depressurized to shrink the mandrel 1 in a manner smaller than the end opening, thereby being pulled out from the fiber-reinforced resin tube body 30A.

[0048] When the mandrel extracting step is performed, the hollow portion of the mandrel body 10 can be decompressed through the communication passage 104 connected to a vacuum pump (not shown).

[0049] Such a mandrel extracting step can be more appropriately performed by, for example, plasticizing the mandrel body 10 made of a thermoplastic resin by heating, etc. Alternatively, the mandrel body 10 can be appropriately performed on, for example, a diamond-cut aluminum thin plate.

[0050] The fiber-reinforced resin tube body 30A involved in the first embodiment of the present invention includes a first carbon fiber reinforced resin layer and a second carbon fiber reinforced resin layer, wherein the first carbon fiber reinforced resin layer has a first carbon fiber; the second carbon fiber reinforced resin layer has a second carbon fiber, which has greater strength and smaller elastic modulus than the first carbon fiber reinforced resin layer, and the first carbon fiber is configured in a manner extending along the length direction of the tube. Therefore, the fiber-reinforced resin tube body 30A can ensure high bending stiffness and high torsional stiffness without causing cost increase by setting the first carbon fiber with relatively high elasticity to extend along the length direction of the tube and setting the carbon fibers of other layers to second carbon fibers with relatively low elasticity.

[0051] The fiber reinforced resin pipe body 30A comprises: A carbon fiber reinforced resin layer having at least one layer of pitch-based carbon fibers as the first carbon fiber reinforced resin layer; and The second carbon fiber reinforced resin layer includes at least two layers of polyacrylonitrile-based carbon fibers. Therefore, the fiber-reinforced resin pipe body 30A does not need to have high elasticity as the PAN-based fibers serving as the second carbon fibers, and thus can appropriately achieve securing of high bending rigidity and high torsional rigidity and cost reduction.

[0052] In the fiber-reinforced resin pipe body 30A, the second carbon fiber-reinforced resin layer is provided radially outside the first carbon fiber-reinforced resin layer. Therefore, the manufacturing efficiency of the fiber-reinforced resin pipe body 30A can be improved by firmly holding the first carbon fiber from the outer peripheral side during the manufacturing stage by the second carbon fiber. In addition, in the fiber-reinforced resin pipe body 30A, since the first carbon fiber reinforced resin layer is arranged radially inside the second carbon fiber reinforced resin layer, high bending rigidity can be ensured with a smaller cross-sectional area (fewer fibers), that is, at a low cost.

[0053] In the fiber-reinforced resin pipe body 30A, the first carbon fiber-reinforced resin layer is laminated by a multi-feed filament winding method. Therefore, during the manufacturing stage, the fiber-reinforced resin pipe body 30A can arrange a plurality of first carbon fibers and second carbon fibers arranged in a circumferential direction in one process and can arrange the first carbon fibers and the second carbon fibers at the same time, thereby improving manufacturing efficiency.

[0054] In addition, the second carbon fiber reinforced resin layer includes a first oblique reinforcement layer and a second oblique reinforcement layer, wherein the first oblique reinforcement layer is an oblique reinforcement layer in which the second carbon fiber has an orientation angle relative to the length direction of the cylinder; the second oblique reinforcement layer is arranged radially outside the first oblique reinforcement layer, and is an oblique reinforcement layer in which the second carbon fiber has an orientation angle relative to the length direction of the cylinder on the opposite side of the first oblique reinforcement layer, and the first carbon fiber reinforced resin layer is a straight reinforcement layer in which the first carbon fiber is arranged parallel to the length direction of the cylinder. Therefore, it is possible to ensure high bending rigidity by the straight reinforcing layer and torsional strength in two directions by the two oblique reinforcing layers.

[0055] In the fiber-reinforced resin pipe body 30A, the first carbon fibers are arranged at equal intervals in the circumferential direction. Therefore, the fiber-reinforced resin pipe body 40A can achieve uniform bending rigidity with respect to the circumferential direction.

[0056] <Second Embodiment> Next, a fiber-reinforced resin pipe body according to a second embodiment of the present invention will be described, focusing on differences from the fiber-reinforced resin pipe body 30A according to the first embodiment.

[0057] like Fig. 9As shown, in the fiber-reinforced resin tube body 30B involved in the second embodiment of the present invention, the first carbon fibers of the first carbon fiber layer 31 are inclined (angle θ) relative to the axial direction of the core shaft body 10. The inclination angle of the first carbon fibers of the first carbon fiber layer 31 is set to be reduced by the torque acting on the cylinder due to the maximum rotation speed supplied to the cylinder (fiber-reinforced resin tube body 30B) (for example, the maximum rotation speed when the vehicle using the power transmission shaft 2 is moving forward), so as to approach the direction parallel to the length direction of the cylinder. That is, with respect to the first carbon fiber layer 31, the orientation angle of the carbon fibers relative to the axis X of the core shaft body 10 is preferably 0° (refer to Fig.10 ).

[0058] In the fiber-reinforced resin tube body 30B involved in the second embodiment of the present invention, the second carbon fiber reinforced resin layer includes a first oblique reinforcement layer and a second oblique reinforcement layer, wherein the first oblique reinforcement layer is an oblique reinforcement layer in which the second carbon fiber has an orientation angle relative to the length direction of the cylinder; the second oblique reinforcement layer is arranged on the radial outside of the first oblique reinforcement layer, and is an oblique reinforcement layer in which the second carbon fiber has an orientation angle relative to the length direction of the cylinder on the opposite side of the first oblique reinforcement layer, and the first carbon fiber of the first carbon fiber reinforced resin layer is inclined relative to the length direction of the cylinder, and the inclination angle of the first carbon fiber reinforced resin layer is set to be reduced by the torque acting on the cylinder due to the maximum rotational speed supplied to the cylinder, thereby approaching a direction parallel to the length direction of the cylinder. Therefore, the fiber-reinforced resin pipe body 30B can achieve desired bending rigidity at the maximum rotation speed, and thus can improve durability reliability.

[0059] <Third Embodiment> Next, a power transmission shaft according to a third embodiment of the present invention will be described mainly with respect to differences from the fiber-reinforced resin pipe bodies 30A and 30B according to the first and second embodiments.

[0060] like Figure 11 to Figure 14 As shown, the fiber reinforced resin pipe body 30C according to the third embodiment of the present invention includes a fourth carbon fiber layer 35 in addition to the first carbon fiber layer 31 , the second carbon fiber layer 32 and the third carbon fiber layer 33 .

[0061] 《Fourth Carbon Fiber Layer》 like Figure 11 to Figure 14 (especially Fig.13), the fourth carbon fiber layer 35 is arranged radially outside the second carbon fiber layer 32 and radially inside the third carbon fiber layer 33, and is composed of a plurality of carbon fibers arranged to cover the second carbon fiber layer 32. More specifically, a carbon fiber aggregate is formed by winding a plurality of carbon fibers into a strip or a bundle, and the fourth carbon fiber layer 35 is formed by arranging the plurality of carbon fiber aggregates with a phase change. The carbon fibers of the fourth carbon fiber layer 35 are extended parallel to the axial direction of the mandrel body 10. That is, with respect to the fourth carbon fiber layer 35, the orientation angle of the carbon fibers relative to the axis X of the mandrel body 10 is 0°.

[0062] The carbon fibers (first carbon fibers) of the fourth carbon fiber layer 35 are pitch-based carbon fibers. The fourth carbon fiber layer 35 is impregnated with a resin 34 (see Figure 8 ) and solidify it to form a first carbon fiber reinforced resin layer. The first carbon fiber reinforced resin layer composed of the fourth carbon fiber layer 35 and the resin 34 is a straight reinforcement layer in which the first carbon fibers are arranged parallel to the length direction of the barrel (fiber reinforced resin tube body 30C). In the fourth carbon fiber layer 35, a plurality of first carbon fibers are arranged at equal intervals in the circumferential direction.

[0063] In the fiber-reinforced resin tube body 30C, the first carbon fibers of the first carbon fiber layer 31 and / or the fourth carbon fiber layer 35 may be constructed to be inclined relative to the axial direction of the core shaft body 10, similarly to the first carbon fibers of the first carbon fiber layer 31 of the fiber-reinforced resin tube body 30B of the second embodiment.

[0064] <Manufacturing method> Next, use Fig.15 A method for manufacturing the power transmission shaft 2 (fiber reinforced resin pipe body 30C) using the mandrel 1 according to the first embodiment of the present invention will be described with reference to the flowchart of FIG.

[0065] In this manufacturing method, in step S5A, as Fig.11 As shown, the first carbon fiber layer 31 is formed on the outer peripheral surface of the mandrel body 10, the first metal component 40 and the second metal component 50. Next, step S5A, in step S5B, as shown in FIG. Fig.12 As shown, the second carbon fiber layer 32 is formed on the outer peripheral surface of the first carbon fiber layer 31 of the mandrel body 10, the first metal component 40 and the second metal component 50. Next, step S5B is performed. In step S5D, as shown in FIG. Fig.13 As shown, the fourth carbon fiber layer 35 is formed on the outer peripheral surface of the second carbon fiber layer 32 of the mandrel body 10, the first metal component 40 and the second metal component 50. Next, step S5D, in step S5C, as shown in FIG. Fig.14As shown, the third carbon fiber layer 33 is formed on the outer peripheral surface of the fourth carbon fiber layer 35 of the mandrel body 10, the first metal component 40 and the second metal component 50. The fourth carbon fiber layer 35 is arranged in a non-crimped structure by a multi-feed filament winding method in a manner simultaneously with the other carbon fiber layers 31, 32, 33.

[0066] In the present manufacturing method, in step S8, the resin 34 (see Figure 8 ) is impregnated into the first carbon fiber layer 31, the second carbon fiber layer 32, the fourth carbon fiber layer 35 and the third carbon fiber layer 33 and cured.

[0067] The fiber-reinforced resin tube body 30C according to the third embodiment of the present invention can appropriately set the natural vibration frequency (bending main resonance point) to a different value, for example, without changing the thickness of the fiber-reinforced resin tube body 30C, compared to the case where only the first carbon fiber layer 31 is thickened. In addition, the fiber-reinforced resin tube body 30C can achieve a desired natural vibration frequency by appropriately changing the thickness of the first carbon fiber layer 31 and the fourth carbon fiber layer 35. In addition, the fiber-reinforced resin tube body 30C can more appropriately ensure high bending rigidity by increasing the total thickness of the so-called straight layers by providing the fourth carbon fiber layer 35 on the basis of the first carbon fiber layer 31.

[0068] The above describes the embodiments of the present invention, but the present invention is not limited to the embodiments and can be appropriately deformed within the scope of the main purpose of the present invention. For example, the large diameter portion (main body) 11 of the spindle body 10 can be expanded into a barrel shape with a diameter decreasing from the central portion to the two ends of the large diameter portion 11, or it can be expanded into a cylindrical shape with the same diameter in the axial range. The expanded shape can be appropriately set according to the shape of the inner circumferential surface of the portion where the large diameter portion 11 is provided in the molding device (mold) 100. In addition, the fluid that flows into and fills the spindle body 10 can be used to heat the thermosetting resin arranged on the outer circumferential surface of the spindle body 10 in addition to pressurizing the spindle body 10 so as to solidify it. In addition, in the case where the fluid is a pressurized fluid that is not heated, the thermosetting resin is heated by other heat sources.

[0069] In addition, the structure can be such that the mandrel 1 is pulled out from the molded fiber-reinforced resin tube body 30A between steps S9 and S10. In addition, the structure can also be such that the resin 44 of step S8 and the heat of the molding device (mold) 100 are used to melt and remove the mandrel body 10. Other heat, electricity, vibration and other energies can also be used to melt and remove the mandrel body 10. In addition, each carbon fiber layer 31 to 33 can be in a so-called curled structure woven into each other. In addition, as a modified example, the fiber body is not limited to carbon fiber, as long as it is a fiber component that can reinforce the resin layer (for example, glass fiber, cellulose fiber, etc.). [Explanation of Reference Numerals]

[0070] 1: mandrel; 10: mandrel body; 30A, 30B, 30C: fiber-reinforced resin tube body (carbon fiber-reinforced resin tube body for transmission shaft); 31: first carbon fiber layer (first carbon fiber, first carbon fiber reinforced resin layer, vertical reinforcement layer); 32: second carbon fiber layer (second carbon fiber, second carbon fiber reinforced resin layer, first oblique reinforcement layer); 33: third carbon fiber layer (second carbon fiber, second carbon fiber reinforced resin layer, second oblique reinforcement layer); 34: resin; 35: fourth carbon fiber layer (first carbon fiber, first carbon fiber reinforced resin layer, vertical reinforcement layer).

Claims

1. A carbon fiber reinforced resin cylinder for a transmission shaft, It is characterized in that It comprises a first carbon fiber reinforced resin layer and a second carbon fiber reinforced resin layer, wherein: The first carbon fiber reinforced resin layer comprises first carbon fibers; The second carbon fiber reinforced resin layer has second carbon fibers having greater strength and smaller elastic modulus than the first carbon fiber reinforced resin layer. The first carbon fibers are arranged to extend along the longitudinal direction of the cylindrical body.

2. The carbon fiber reinforced resin cylinder for a transmission shaft according to claim 1 ， It is characterized in that comprising: a carbon fiber reinforced resin layer having at least one layer of pitch-based carbon fiber as the first carbon fiber reinforced resin layer; and The second carbon fiber reinforced resin layer includes at least two layers of polyacrylonitrile-based carbon fibers.

3. The carbon fiber reinforced resin cylinder for a propeller shaft according to claim 1, It is characterized in that The second carbon fiber reinforced resin layer is provided radially outside the first carbon fiber reinforced resin layer.

4. The carbon fiber reinforced resin cylinder for a propeller shaft according to claim 1, It is characterized in that The first carbon fiber reinforced resin layer is laminated by a multi-feed filament winding method.

5. The carbon fiber reinforced resin cylinder for a propeller shaft according to claim 2, It is characterized in that The second carbon fiber reinforced resin layer includes a first oblique reinforcement layer and a second oblique reinforcement layer, wherein: The first oblique reinforcement layer is an oblique reinforcement layer in which the second carbon fiber has an orientation angle relative to the length direction of the cylinder; The second oblique reinforcing layer is disposed radially outside the first oblique reinforcing layer, and is an oblique reinforcing layer in which the second carbon fibers have an orientation angle opposite to that of the first oblique reinforcing layer with respect to the length direction of the cylinder. The first carbon fiber reinforced resin layer is a straight reinforcement layer in which the first carbon fibers are arranged parallel to the longitudinal direction of the cylinder.

6. The carbon fiber reinforced resin cylinder for a propeller shaft according to claim 2, It is characterized in that The second carbon fiber reinforced resin layer includes a first oblique reinforcement layer and a second oblique reinforcement layer, wherein: The first oblique reinforcement layer is an oblique reinforcement layer in which the second carbon fiber has an orientation angle relative to the length direction of the cylinder; The second oblique reinforcing layer is disposed radially outside the first oblique reinforcing layer, and is an oblique reinforcing layer in which the second carbon fibers have an orientation angle opposite to that of the first oblique reinforcing layer with respect to the length direction of the cylinder. The first carbon fibers of the first carbon fiber reinforced resin layer are arranged obliquely with respect to the longitudinal direction of the cylinder. The inclination angle of the first carbon fiber reinforced resin layer is set to be reduced by the torque acting on the barrel due to the maximum rotation speed supplied to the barrel, thereby approaching a direction parallel to the longitudinal direction of the barrel.

7. The carbon fiber reinforced resin cylinder for a propeller shaft according to claim 1, It is characterized in that The first carbon fibers are arranged at equal intervals in the circumferential direction.

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