JP6759878B2 - Power transmission shaft for automobiles - Google Patents

Description

The present invention relates to a power transmission shaft for an automobile.

Due to its excellent strength and light weight, a hollow pipe made of carbon fiber reinforced plastic and a power transmission shaft for automobiles equipped with metal parts such as flanges provided at both ends in the axial direction of the hollow pipe ( Propeller shaft) is widely used (for example, Patent Document 1).

The power transmission shaft, which rotates around the shaft during traveling, is usually mainly subjected to torsional stress. Therefore, the power transmission shaft needs to have sufficient strength to suppress breakage due to torsional stress during rotation. In particular, since the power transmission shaft used in a racing car has severe operating conditions, it is required to have particularly excellent resistance to torsional stress during rotation and resonance. However, the conventional power transmission shaft as in Patent Document 1 does not have sufficient resistance to torsional stress and resonance during rotation, and it has been important to improve the resistance.

JP-A-2007-196681

An object of the present invention is to provide a power transmission shaft for an automobile having excellent resistance to torsional stress and resonance during rotation.

As a result of diligent studies by the present inventors, it has been found that the problem of damage to the power transmission shaft used under harsh conditions such as racing cars is due to the following factors. Specifically, the natural frequency of 1/2 bending vibration and the natural frequency of torsional vibration are close to each other, and 1/2 bending resonance and torsional resonance occur at the same time at a specific engine speed, and the power transmission shaft. It was found that the load was extremely heavy and the vibration was broken. Then, the present inventors further studied and separated the primary natural frequency and 1/2 natural frequency of bending vibration from the natural frequency of torsional vibration by a specific ratio or more to obtain bending resonance. The present invention has been completed by finding that the simultaneous occurrence of torsional resonance is suppressed and the resistance to torsional stress and resonance during rotation is improved.

The present invention has the following configurations.
[1] A power transmission shaft for an automobile including a hollow pipe made of carbon fiber reinforced plastic and a metal component provided at at least one end of the hollow pipe in the axial direction.
When the primary natural frequency of bending vibration is f _A (Hz), the natural frequency of 1/2 of bending vibration is f _B (Hz), and the natural frequency of torsion vibration is f _C (Hz).
Power transmission for automobiles where f _B / f _C ≥ 1.1 or f _C / f _B ≥ 1.1 and f _A / f _C ≥ 1.1 or f _C / f _A ≥ 1.1 axis.
[2] 1.1 ≤ f _B / f _C ≤ 1.5 or 1.1 ≤ f _C / f _B ≤ 1.5, and 1.1 ≤ f _A / f _C ≤ 3.0 or 1. The power transmission shaft for an automobile according to [1], wherein 1 ≦ f _C / f _A ≦ 3.0.
[3] The power transmission shaft for an automobile according to [1] or [2], wherein the static torsional strength of the power transmission shaft is greater than 2500 Nm.
[4] The power transmission shaft for an automobile according to any one of [1] to [3], wherein the hollow pipe contains both Pitch-based carbon fibers and polyacrylonitrile-based carbon fibers.
[5] The hollow pipe includes the Pitch-based carbon fibers oriented along the axial direction and the polyacrylonitrile-based carbon fibers oriented along the direction obliquely intersecting the axial direction. [4] Power transmission shaft for automobiles described in.
[6] The power transmission shaft for an automobile according to [4] or [5], wherein the Pitch-based carbon fiber has a tensile elastic modulus of 640 GPa or more.
[7] The _{f A} is 160~250Hz, [1] ~ power transmission shaft for an automobile according to any one of [6].
[8] The power transmission shaft for an automobile according to any one of [1] to [7], which has a total mass of 4.1 kg or less.

The power transmission shaft for an automobile of the present invention has excellent resistance to torsional stress and resonance during rotation.

It is sectional drawing which showed an example of the power transmission shaft for an automobile of this invention.

Hereinafter, an example of the power transmission shaft for an automobile of the present invention will be described, but the present invention is not limited to the following description.
As shown in FIG. 1, the power transmission shaft 1 for an automobile of the present embodiment (hereinafter, simply referred to as "power transmission shaft 1") includes a cylindrical hollow pipe 10 made of carbon fiber reinforced plastic and a hollow pipe 10. The metal parts 12 and 14 provided at both ends in the axial direction of the above are provided.

In the power transmission shaft 1, the primary natural frequency of bending vibration is f _A (Hz), the natural frequency of 1/2 of bending vibration is f _B (Hz), and the natural frequency of torsional vibration is f _C (Hz). When, both the following conditions (1) and (2) are satisfied.
(1) f _B / f _C ≧ 1.1 or f _C / f _B ≧ 1.1.
(2) f _A / f _C ≧ 1.1 or f _C / f _A ≧ 1.1.

When the power transmission shaft 1 satisfies both the condition (1) and the condition (2), when the power transmission shaft 1 is rotated, the maximum twist angle is generated in the power transmission shaft 1 due to the torsional resonance. The number and the number of rotations at which the maximum displacement occurs in the central portion of the power transmission shaft 1 due to bending resonance can be sufficiently separated. That is, in the power transmission shaft 1, the torsional resonance and the bending resonance can occur at different rotation speeds. As a result, it is possible to suppress the simultaneous occurrence of torsional resonance and bending resonance in the power transmission shaft 1 at a specific engine speed. Therefore, the power transmission shaft 1 has excellent resistance to torsional stress and resonance during rotation.

The number of revolutions at which torsional resonance occurs is determined by the entire power train, including the engine and drive wheels. Since the power transmission shaft is a part of the power train, even if the torsional characteristics of the power transmission shaft alone are changed, it is greatly affected by other parts. Therefore, changing the torsional resonance rotation speed by changing the characteristics of the power transmission shaft alone has a limited effect.

In condition (1), f _B / f _C ≥ 1.1 because it is easier to adjust the natural frequency f _B of bending vibration than the natural frequency f _C of torsional vibration. Alternatively, f _C / f _B ≥ 1.1 is preferable, and 1.1 ≤ f _B / f _C ≤ 1.5 or 1.1 ≤ f _C / f _B ≤ 1.5 is more preferable. It is more preferable that 1.1 ≦ f _B / f _C ≦ 1.3 or 1.1 ≦ f _C / f _B ≦ 1.3. The larger the value of f _B / f _C or f _C / f _B , the less likely it is that torsional resonance and 1/2 bending resonance will occur at the same time. Therefore, power with excellent resistance to torsional stress and resonance during rotation. It tends to be a transmission axis. Further, when the value of f _B / f _C or f _C / f _B is not more than the upper limit value, it becomes easy to adjust the 1/2 natural frequency f _B of the bending vibration.

In condition (2), f _A / f _C ≧ 1.1 or f from the point that it is easier to adjust the primary natural frequency f _A of bending vibration than the natural frequency f _C of torsional vibration. _C / f _A ≧ 1.1 is preferable, 1.1 ≦ f _A / f _C ≦ 3.0 or 1.1 ≦ f _C / f _A ≦ 3.0 is more preferable. It is more preferable that 2 ≦ f _A / f _C ≦ 2.5 or 2.2 ≦ f _C / f _A ≦ 2.5. The larger the value of f _A / f _C or f _C / f _A , the less likely it is that torsional resonance and primary bending resonance will occur at the same time. Therefore, the power transmission shaft has excellent resistance to torsional stress and resonance during rotation. It is easy to become. Further, when the value of f _A / f _C or f _C / f _A is not more than the upper limit value, the primary natural frequency f _A of the bending vibration can be easily adjusted.
Since the 1/2 natural frequency f _B of the bending vibration is half the value of the primary natural frequency f _A , f _B / f _C ≧ 1.1 or f _C / f _B ≧ 1 as the condition (1). If .1 is satisfied, the condition (2) is always satisfied.

As a method of adjusting the values of f _A / f _C or f _C / f _A and f _B / f _C or f _C / f _B , for example, the elastic modulus and orientation of the carbon fibers used in the hollow pipe 10 are adjusted. Thereby, a method of adjusting the primary natural frequency f _A and 1/2 natural frequency f _B of the bending vibration can be mentioned. The use of carbon fibers with high elastic modulus tends to increase the primary natural frequency f _A and 1/2 natural frequency f _B of bending vibration, and the use of carbon fiber with low elastic modulus tends to increase the primary natural frequency of bending vibration. The frequency f _A and 1/2 natural frequency f _B tend to be low. Further, the more carbon fibers oriented along the axial direction of the hollow pipe 10, the higher the primary natural frequency f _A and 1/2 natural frequency f _{B of} the bending vibration tend to be, and the axial direction of the hollow pipe 10 tends to be higher. The smaller the number of carbon fibers oriented along, the lower the primary natural frequency f _A and 1/2 natural frequency f _{B of} bending vibration tend to be.

Primary natural frequency _{f A} of the bending vibration power transmission shaft 1 is preferably 160～250Hz, more preferably 165～220Hz, more preferably 170～200Hz. When f _A is within the above range, it is easy to obtain a power transmission shaft that satisfies the conditions (1) and (2). When f _A is equal to or greater than the lower limit value, it is easy to obtain a power transmission shaft satisfying f _A / f _C ≧ 1.1. When f _A is not more than the upper limit value, it becomes easy to adjust f _A from the viewpoint of availability of carbon fibers having a high elastic modulus.

The 1/2 natural frequency f _B of the bending vibration of the power transmission shaft 1 is preferably 80 to 125 Hz, more preferably 83 to 110 Hz, and even more preferably 85 to 100 Hz. When f _B is within the above range, it is easy to obtain a power transmission shaft that satisfies the conditions (1) and (2). When f _B is equal to or greater than the lower limit value, it is easy to obtain a power transmission shaft satisfying f _B / f _C ≧ 1.1. When f _B is not more than the upper limit value, it becomes easy to adjust f _B from the viewpoint of availability of carbon fibers having a high elastic modulus.

The natural frequency f _C of the torsional vibration of the power transmission shaft 1 attached to the automobile is preferably 50 to 100 Hz, more preferably 58 to 90 Hz, and even more preferably 65 to 83 Hz. When f _C is within the above range, it is easy to obtain a power transmission shaft that satisfies the conditions (1) and (2).

The primary natural frequencies f _A and 1/2 natural frequencies f _B of the bending vibration of the power transmission shaft and the natural frequencies f _C of the torsional vibration are determined by using the power transmission shaft in the drive system of the automobile. It can be measured by a bench test that incorporates the layout. For example, f _A , f _B and f _C can be measured by a bench test incorporating a layout that connects the engine and the transaxle using a power transmission shaft.

The hollow pipe 10 is made of carbon fiber reinforced plastic.
The carbon fibers used in the hollow pipe 10 are not particularly limited, and examples thereof include Pitch-based carbon fibers and polyacrylonitrile (PAN) -based carbon fibers.

What is graphite-based carbon fiber? "Mesophase pitch, that is, a pitch showing a liquid crystal structure generated by processing petroleum tar, coal tar, etc., or an artificially synthesized mesophase pitch is spun, infusible, and further carbonized. -It means that it is an aggregate of fibers composed mainly of "filament fibers, which are produced by graphitization and whose graphite crystal structure is highly developed in the fiber axis direction and are substantially composed of carbon only". Pitch-based carbon fibers have the advantage of having a high elastic modulus.

The PAN-based carbon fiber is a "filament fiber made of substantially carbon only, which is produced by flame-resistant a fiber made of a polyacrylonitrile-based resin polymerized with acrylonitrile as a main component and further carbonized and graphitized." It means that it is an aggregate of fibers composed as a main component. PAN-based carbon fibers have the advantage of high strength.

The carbon fiber used for the hollow pipe 10 may be one type or two or more types. The hollow pipe preferably contains both Pitch-based carbon fibers and PAN-based carbon fibers. By using Pitch carbon fiber, it is easy to increase the primary natural frequency f _A and 1/2 natural frequency f _B of bending vibration, and by using PAN carbon fiber, the natural frequency f of torsional vibration f. _Since it is easy to suppress the rise of _C , it is easy to obtain a power transmission shaft that satisfies f _A / f _C ≧ 1.1 and f _B / f _C ≧ 1.1.

When the Pitch-based carbon fiber and the PAN-based carbon fiber are used in combination, the hollow pipe is formed by the Pitch-based carbon fiber oriented along the axial direction and the PAN-based carbon fiber oriented diagonally with respect to the axial direction. Is preferably included. Said shaft by including Pitch based carbon fibers oriented along the direction, the bending higher easily the primary natural frequency f _A and 1/2 natural frequency f _B of the vibration, oblique with respect to the axial direction By using PAN-based carbon fibers oriented in the direction, f _A / f _C ≧ 1.1 without increasing the natural frequency f _C of the torsional vibration more than necessary while ensuring the torsional strength. Alternatively, it is easy to obtain a power transmission shaft that satisfies f _B / f _C ≧ 1.1.

The tensile elastic modulus of the Pitch-based carbon fiber used is preferably 640 GPa or more, more preferably 700 GPa or more, and even more preferably 760 GPa or more. If the tensile elastic modulus of the Pitch-based carbon fiber is equal to or higher than the lower limit, the primary natural frequency f _A and 1/2 natural frequency f _{B of} the bending vibration are high, and f _A / f _C ≧ 1.1 or f _B /. It is easy to obtain a power transmission shaft that satisfies f _C ≧ 1.1. The tensile elastic modulus of the Pitch-based carbon fiber is preferably 800 GPa or less. Carbon fibers having a high elastic modulus are poorly available, costly, and have poor adhesion between the carbon fibers and the resin, and resonance may cause the carbon fibers and the resin to peel off.
The tensile elastic modulus of the carbon fiber is a value measured by the A method of JIS R7608: 2007 (ISO16018: 2004).

The tensile elastic modulus of the PAN-based carbon fiber used is preferably 235 to 325 GPa, more preferably 235 to 250 GPa. When the tensile elastic modulus of the PAN-based carbon fiber is at least the lower limit value, the natural frequency of the torsional vibration is not increased more than necessary while ensuring the necessary torsional strength. When the tensile elastic modulus of the PAN-based carbon fiber is not less than the upper limit value, the natural frequency of the torsional vibration is higher than when it is more than the lower limit value, but the torsional strength can be increased.

As the matrix resin used for the carbon fiber reinforced plastic, a known matrix resin usually used for a power transmission shaft for an automobile can be used. Specific examples of the matrix resin include thermoplastic resins such as epoxy resin, unsaturated polyester resin, vinyl ester resin, phenol resin, and modified epoxy resin, or polyamide resin, polyethylene terephthalate resin, ABS resin, and polypropylene resin. Epoxy resin can be mentioned. Of these, epoxy resins are preferable from the viewpoints of heat resistance, strength, and moldability. As the matrix resin, one type may be used alone, or two or more types may be used in combination.

The static torsional strength of the power transmission shaft 1 is preferably greater than 2500 Nm, more preferably greater than 3000 Nm, and even more preferably greater than 4000 Nm. The greater the static torsional strength, the easier it is to suppress damage due to torsional resonance of the power transmission shaft. The torsional strength is improved by increasing the number of carbon fibers oriented along the direction oblique with respect to the axial direction of the power transmission shaft 1, but at the same time, the natural frequency of the torsional resonance increases, so that the power is increased. The static torsional strength of the transmission shaft 1 is preferably 7500 Nm or less. The static torsional strength of the power transmission shaft can be changed by adjusting the type and orientation of the carbon fibers used.

The metal parts 12 and 14 may be appropriately selected according to the layout of the drive system of the automobile using the power transmission shaft 1. For example, a fixed flange for connecting to an engine, a transmission, a differential gear, or the like, a universal joint, or the like. Can be mentioned.
As the materials of the metal parts 12 and 14, known materials can be used, and examples thereof include aluminum alloys.

The form of connection between the hollow pipe 10 and the metal parts 12 and 14 is not particularly limited, and examples thereof include a form of connecting with an adhesive and a form of connecting with serrations. Among them, the connection form by serration breaks the carbon fiber, and therefore the connection form by an adhesive is preferable in that higher strength can be easily obtained.

In this example, the metal component 12 includes a flange portion 12a and a cylindrical tubular portion 12b protruding from one surface of the flange portion 12a. Then, with the tip of the tubular portion 12b of the metal component 12 inserted into one end side of the hollow pipe 10, the outer surface of the tip of the tubular portion 12b and the inner surface of the hollow pipe 10 are connected by an adhesive. ing. Similarly, in the metal part 14, the tip of the cylindrical cylinder 14b protruding from one surface of the flange 14a is inserted into the other end of the hollow pipe 10 and the tip of the cylinder 14b is inserted. The outer surface and the inner surface of the hollow pipe 10 are connected by an adhesive.

The adhesive used to connect the hollow pipe 10 and the metal parts 12 and 14 may be any adhesive that can connect the hollow pipe 10 and the metal parts 12 and 14 with sufficient adhesive strength. For example, an epoxy adhesive or acrylic. Examples include system adhesives. As the adhesive, one type may be used alone, or two or more types may be used in combination.

The total mass of the power transmission shaft is preferably 4.1 kg or less, more preferably 4.0 kg or less, and even more preferably 3.8 kg or less. When the total mass of the power transmission shaft 1 is not more than the upper limit value, the weight can be reduced, and the primary natural frequency f _A and 1/2 natural frequency f _B of bending vibration can be easily increased.

The length of the power transmission shaft is not particularly limited, and may be appropriately set according to the layout of the drive system to be used. For example, in the case of a two-joint type power transmission shaft, the length of the power transmission shaft can be 1400 to 1600 mm.
The inner and outer diameters of the hollow pipe are not particularly limited, and may be appropriately set according to the layout of the drive system to be used. For example, the inner diameter of the hollow pipe can be 60 to 90 mm, and the outer diameter can be 65 to 100 mm. The thinner the wall thickness of the hollow pipe, the lighter the weight, and it is easy to increase the primary natural frequency f _A and 1/2 natural frequency f _B of bending vibration.

The layout of the drive system of an automobile using the power transmission shaft of the present invention is not particularly limited. For example, the power transmission shaft of the present invention serves as a propeller shaft between a transmission and a differential gear in layouts such as front engine / front drive (FF), front engine / rear drive (FR), and midship engine / rear drive (MR). Can be used. Further, the power transmission shaft of the present invention may be used as the propeller shaft between the engine and the transaxle in the transaxle layout. Since the power transmission shaft of the present invention is particularly excellent in resistance to torsional stress and resonance during rotation, it is particularly effective to use it for a transaxle layout with a larger load because the rotation fluctuation of the engine is directly transmitted to the shaft. is there.

Further, since the power transmission shaft of the present invention is particularly excellent in resistance to torsional stress and resonance during rotation, one power transmission shaft connects the engine to the transaxle and the transmission to the differential gear2. Especially useful as a joint type. The power transmission shaft of the present invention may be used as a three-joint type using two power transmission shafts, but the total mass of the power transmission shaft increases as the number of joints increases.

Further, since the power transmission shaft of the present invention is particularly excellent in resistance to stress and resonance during rotation, it is used in an automobile equipped with an in-line 4-cylinder turbo engine having a large rotation fluctuation and a larger load on the power transmission shaft. Is especially useful. The power transmission shaft of the present invention may be used in an automobile provided with an engine other than an in-line 4-cylinder turbo engine.

(Production method)
The method for manufacturing the power transmission shaft of the present invention is not particularly limited, but a method of wrapping a plurality of prepreg sheets in which a carbon fiber base material is impregnated with a matrix resin around a mandrel is preferable. By adopting the sheet winding method, carbon fibers, particularly Pitch-based carbon fibers, can be oriented along the axial direction of the hollow pipe. Therefore, a power transmission shaft having a high primary natural frequency f _A and 1/2 natural frequency f _{B of} bending vibration and satisfying f _A / f _C ≧ 1.1 or f _B / f _C ≧ 1.1 is manufactured. It becomes easy. Also, the device for manufacturing the hollow pipe is simple.

The carbon fiber base material is not particularly limited, and may be a UD material in which carbon fibers are aligned in one direction, or a cloth material in which carbon fibers are woven.

In the power transmission shaft for automobiles of the present invention described above, the conditions are the primary natural frequency f _A of bending vibration, 1/2 natural frequency f _{B of} bending vibration, and the natural frequency f _{C of} torsional vibration. Both (1) and condition (2) are satisfied. As a result, simultaneous occurrence of bending resonance and torsional resonance at a specific engine speed is suppressed, so that a large load is less likely to be applied to the power transmission shaft. For this reason, the power transmission shaft for automobiles of the present invention has excellent resistance to torsional stress and resonance during rotation.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to the following description.

[Static torsional strength]
The static torsional strength of the power transmission shaft in each example was measured by a torsion tester (PKO-00410 manufactured by Tokyo Impact Machinery Co., Ltd.), and the torque at which the power transmission shaft was broken was taken as the static torsional strength.

[Primary natural frequency f _A and 1/2 natural frequency f _{B of} bending vibration, natural frequency f _{C of} torsional vibration]
The measurement of the primary natural frequency f _A and 1/2 natural frequency f _B of the bending vibration of the power transmission shaft and the natural frequency f _C of the torsional vibration of each example incorporates the transaxle layout including the engine. Determined by bench test. The bench test was carried out by a method of sweeping up to the upper limit of the engine speed (9500 rpm) in 30 seconds with the full load of the 3rd gear fixed.
Regarding the twist of the power transmission shaft, the phase difference between both ends of the power transmission shaft in the axial direction was measured to measure the value at which the twist angle was maximized. The engine speed (rotational speed of the power transmission shaft) at which the torsional angle of the power transmission shaft is maximized was defined as the natural frequency f _C (Hz) of the torsional vibration.
Regarding the bending of the power transmission shaft, the value at which the bending displacement at the center of the power transmission shaft in the axial direction was maximized was measured. The engine speed (speed of the power transmission shaft) that maximizes the displacement of the center of the power transmission shaft is set to 1/2 natural frequency f _B (Hz) of the bending vibration, and 1/2 natural frequency f _B (Hz). The value obtained by multiplying by 2 is defined as the primary natural frequency f _A (Hz) of bending vibration.

[Damage test]
_A bench test incorporating a transaxle layout similar to the measurements of f _A , f _B and f _C confirmed the presence or absence of damage to the power transmission shaft.

[Manufacturing Example 1]
Epoxy resin is impregnated with a carbon fiber base material having a texture of 250 g / m ² in which Pitch-based carbon fibers (trade name "Dialed ^TM ", manufactured by Mitsubishi Rayon Co., Ltd., tensile elastic modulus: 790 GPa) are aligned in one direction. A prepreg sheet (prepreg A) was obtained.

[Manufacturing Example 2]
PAN-based carbon fibers (trade name "Pyrofil ^TM ", manufactured by Mitsubishi Rayon Co., Ltd., tensile modulus: 240 GPa) are arranged in one direction, and carbon fiber base materials with a grain size of 175 g / m ² and 100 g / m ² are made of epoxy. Prepreg sheets (prepregs B and C) impregnated with resin were obtained.

[Example 1]
Hollow pipes were produced by the sheet winding method using the prepregs A, B, and C obtained in Production Examples 1 and 2.
Next, a fixed flange made of an aluminum alloy was adhered to each of both ends of the hollow pipe in the axial direction using an epoxy adhesive to obtain a power transmission shaft. The total length of the power transmission shaft was 1583 mm, the outer diameter was 82.8 mm, and the inner diameter was 76.3 mm.
The primary natural frequency f _A of the bending vibration was 180 Hz, the 1/2 natural frequency f _B was 90 Hz, and the natural frequency f _C of the torsional vibration was 77 Hz. f _A / f _C was 2.3 and f _B / f _C was 1.2. The total mass of this power transmission shaft was 3.8 kg. As a result of manufacturing the same power transmission shaft and performing a static torsion test, the static torsion strength was 3200 Nm. In the breakage test, the breakage of the power transmission shaft was suppressed.

[Example 2]
A power transmission shaft was obtained in the same manner as in Example 1 except that the number of laminated prepregs A, B, and C and the orientation of carbon fibers were adjusted. The total length of the power transmission shaft was 1583 mm, the outer diameter was 83.4 mm, and the inner diameter was 76.3 mm. The primary natural frequency f _A of the bending vibration of the obtained power transmission shaft, 1/2 natural frequency f _B , the natural frequency f _C of the torsional vibration, f _A / f _C , f _B / f _C , total Table 1 shows the results of measuring the mass and the static torsional strength. In the breakage test, the breakage of the power transmission shaft was suppressed.

[Example 3]
A power transmission shaft was obtained in the same manner as in Example 1 except that the number of laminated prepregs A, B, and C and the orientation of carbon fibers were adjusted. The total length of the power transmission shaft was 1583 mm, the outer diameter was 83.7 mm, and the inner diameter was 76.3 mm. The primary natural frequency f _A of the bending vibration of the obtained power transmission shaft, 1/2 natural frequency f _B , the natural frequency f _C of the torsional vibration, f _A / f _C , f _B / f _C , total Table 1 shows the results of measuring the mass and the static torsional strength. In the breakage test, the breakage of the power transmission shaft was suppressed.

[Comparative Example 1]
As the power transmission shaft to be compared, the power transmission shaft having the specifications shown in Table 2 was prepared.
Tables show the primary natural frequencies f _A , 1/2 natural frequencies f _B , and natural frequencies f _C , f _A / f _C, and f _B / f _C of the bending vibration of the obtained power transmission shaft. Shown in 3. In the breakage test, the hollow pipe of the power transmission shaft was broken.

[Comparative Example 2]
As the power transmission shaft to be compared, the power transmission shaft having the specifications shown in Table 2 was prepared.
Tables show the primary natural frequencies f _A , 1/2 natural frequencies f _B , and natural frequencies f _C , f _A / f _C, and f _B / f _C of the bending vibration of the obtained power transmission shaft. Shown in 3. In the breakage test, the hollow pipe of the power transmission shaft was broken.

1 Automobile power transmission shaft 10 Hollow pipe 12, 14 Metal parts

Claims (8)

A power transmission shaft for an automobile including a hollow pipe made of carbon fiber reinforced plastic and a metal component provided at at least one end in the axial direction of the hollow pipe.
When the primary natural frequency of bending vibration is f _A (Hz), the natural frequency of 1/2 of bending vibration is f _B (Hz), and the natural frequency of torsion vibration is f _C (Hz).
Power transmission for automobiles where f _B / f _C ≥ 1.1 or f _C / f _B ≥ 1.1 and f _A / f _C ≥ 1.1 or f _C / f _A ≥ 1.1 axis. 1.1 ≤ f _B / f _C ≤ 1.5 or 1.1 ≤ f _C / f _B ≤ 1.5, and 1.1 ≤ f _A / f _C ≤ 3.0 or 1.1 ≤ f The power transmission shaft for an automobile according to claim 1, wherein _C / f _A ≤ 3.0. The power transmission shaft for an automobile according to claim 1 or 2, wherein the static torsional strength of the power transmission shaft is greater than 2500 Nm. The power transmission shaft for an automobile according to any one of claims 1 to 3, wherein the hollow pipe contains both Pitch-based carbon fibers and polyacrylonitrile-based carbon fibers. The fourth aspect of claim 4, wherein the hollow pipe includes the Pitch-based carbon fibers oriented along the axial direction and the polyacrylonitrile-based carbon fibers oriented along a direction oblique to the axial direction. Power transmission shaft for automobiles. The power transmission shaft for an automobile according to claim 4 or 5, wherein the Pitch-based carbon fiber has a tensile elastic modulus of 640 GPa or more. Wherein _{f A} is a 160～250Hz, power transmission shaft for an automobile according to any one of claims 1-6. The power transmission shaft for an automobile according to any one of claims 1 to 7, wherein the total mass is 4.1 kg or less.

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