JP3191528B2 - Propeller shaft and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a propeller shaft for an automobile or the like and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, it has been strongly desired to reduce the weight of automobiles for the purpose of improving fuel efficiency from the viewpoint of energy saving. As one of the means, it has been studied to replace the propeller shaft from one made of metal with one made of FRP (fiber reinforced plastic). At this time, there are various types of reinforcing fibers to be used. For example, carbon fibers, glass fibers, aramid fibers, and the like have been studied. Among them, CFRP in which carbon fibers are used as reinforcing fibers is particularly preferred in terms of strength and elastic modulus. (Carbon fiber reinforced plastic) is considered to be promising.

[0003] A propeller shaft of an automobile needs to transmit a large torque generated from an engine, and therefore needs a torsional strength of about 100 to 400 kgfm. Conventional propeller shafts made of CFRP, in particular, the main body cylindrical portion thereof, have a laminating angle, a laminating configuration, and a shaft size (see, for example, JP-A-2-236014) for transmitting necessary torque. It is designed with parameters such as inner diameter, outer diameter, and wall thickness), the type of reinforcing fiber to be used, and the fiber content. By using these design parameters, it is possible to predict the properties of the propeller shaft to some extent, but often the torsional strength of the propeller shaft expected from the design and the properties of the actually formed propeller shaft are often It could be very different and could be problematic. In such a case, there is no other way than to cope with the problem by increasing the design safety factor more than necessary.

In a propeller shaft made of FRP or CFRP, the main body cylinder is made of FRP or CFR.
Although made of P, the joint is made of metal, so that it is impossible to join by welding like a propeller shaft made entirely of steel. It is necessary to achieve the above-mentioned torsional strength with respect to the joining strength between the main body cylinder and the metal joint, but it is hard to say that conditions and specifications such as press-fitting for this purpose are not necessarily established.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the conventional FRP propeller shaft and to make the FRP main body cylinder exhibit a high torsional strength as expected. , And a method of manufacturing the same.

It is another object of the present invention to preferably establish a specification capable of exhibiting high torsional strength and to provide a desirable structure for the joint between the FRP main body cylinder and the metal joint.

[0007]

To achieve the above object, according to the Invention The propeller shaft of the present invention is a propeller shaft having a FRP binding body tube, when viewed cross-section perpendicular to the main body tube, a rotary shaft, in contact with adjacent small between the reinforcing fiber bundles
Are boundary formed extending in Kutomo circumferential direction, the boundary consists of those characterized by the this <br/> extending while forming irregularities for the radial direction of the main body tube.

[0008] the boundary is preferably also against the circumferential direction of the main body tube extends continuously while forming a concave <br/> convex.
For example, the cross-sectional shape of each of the reinforcing fiber bundle in a cross section perpendicular to the rotation axis is polygonal, the boundary formed between the reinforcing fiber bundle adjacent to each other <br/> physician in the cross section is, both reinforced
At least two vertices of each polygon of the fiber bundle and between the two vertices
A structure is formed to include a one side of the.

Such a cross-sectional structure can be achieved, in particular, by twisting individual reinforcing fiber bundles. Therefore, a method for manufacturing a propeller shaft according to the present invention includes a method for manufacturing a propeller shaft having an FRP main body cylinder,
The method of manufacturing a main body tube comprises a step of twisting individual reinforcing fiber bundles and a step of winding the twisted reinforcing fiber bundle around a mandrel.

Still preferably, in a method for manufacturing a propeller shaft according to the present invention, the method for manufacturing a propeller shaft having a main body cylinder made of FRP includes a step of manufacturing the main body cylinder.
(B) twisting individual reinforcing fiber bundles;
A step of aligning a plurality of twisted reinforcing fiber bundles; (c) a step of winding a plurality of aligned reinforcing fiber bundles around a mandrel; and (d) a plurality of reinforcing fibers when winding the mandrel. Adjusting the relationship among the bundle width W, the number of windings N in the circumferential direction, the winding angle θ, the winding diameter d, and the circular constant π such that W × N> πdcos θ. And a method characterized by the following.

In the case of a laminated structural material such as FRP, monofilaments of reinforcing fibers are usually uniformly dispersed in one layer. That is, it is a common practice to stabilize the material characteristics by making the fiber amount related to the characteristics of FRP uniform everywhere. Conventional propeller shafts are designed based on this concept,
In the cross section perpendicular to the rotation axis of the propeller shaft,
A layer in which monofilaments of the reinforcing fibers are uniformly dispersed forms a laminated structure in which the layers are concentrically overlapped. In this case, since the overlapping layers and the layers have different reinforcing directions (lamination angles) of the reinforcing fibers, the boundaries between the layers are clear, and between these layers, there is a thin resin layer concentric with the reinforcing layer (no reinforcing fibers). ing. When a torque is applied to such a propeller shaft, a shear stress corresponding to the torsional torque is generated in each layer in a radial direction of the shaft. At this time, the resin layer existing in a concentric shape described above has a low shear strength. Therefore, this layer is a starting point of the destruction. As a result, the propeller shaft breaks at a strength level lower than the torsional strength expected from reinforcement with the reinforcing fibers.

In view of this destruction mechanism, the present inventors have proposed FR
Since P is a laminated structure of layers having different lamination angles, the existence of an extremely thin, inter-layer resin layer cannot be avoided, but the resin layer exists concentrically and is distributed in the radial direction due to a torque load. As a result of diligent research on a structure that resolves the conventional state in which only a thin resin layer is used, the present invention has been achieved.

That is, a boundary is formed between the reinforcing fiber bundles,
When viewed the boundary in the circumferential direction, by the structure having unevenness against radially, FRP made cylindrical body shear stress distribution in the radial direction of the (main body tube), low shear strength, thin resin layer Only to avoid receiving it.
In addition, it is possible to form a cross-sectional structure in which the reinforcing fiber bundles are physically (geometrically) engaged with each other, efficiently transmit the applied torque, and increase the rate of occurrence of the torsional strength predicted by design. It becomes possible.

The structure in which the boundaries between the reinforcing fiber bundles can exist can be obtained by forming a twisted reinforcing fiber bundle. Twisting has an appropriate value depending on the type of fiber and the number of monofilaments constituting the reinforcing fiber bundle.
20 turns / m is good. It is not preferable to apply a twist exceeding 20 turns / m, because resin impregnation may become impossible. If it is less than 2 turns / m, the form of the reinforcing fiber bundle is not stable, and the effect of improving the torsional strength expression rate of the formed propeller shaft cannot be obtained. Also, twisting the reinforcing fiber bundle has the advantage of improving the yarn passage property during molding and increasing the production efficiency.

In the method of manufacturing the propeller shaft made of FRP of the present invention, a filament winding molding method is used. The number of twists according to the specification is given to each reinforcing fiber bundle used, and a plurality of twists are arranged so as not to intersect. The reinforcing fiber bundle is directly impregnated with the resin and wound around a mandrel so as not to disturb the aligned state.
At this time, the width W when wound around the mandrel and the number of windings N (integer) in the circumferential direction are adjusted from the winding angle θ, the winding diameter d, and the circular constant π such that W × N> πdcos θ. Molding.

[0016] In W × N ≦ dcosθ, to try to spread the thread to fill the gaps between the reinforcing fiber bundle, the cross-sectional shape of the reinforcing fiber bundle is flat, i.e. becomes a rectangle, is formed between the reinforcing fiber bundle The boundary is concentric and continuous, and the torsional strength required for a propeller shaft of an automobile or the like may not be obtained, which is not preferable.

The torsional strength of the main body cylinder is required to be about 100 to 400 kgf · m, especially for a propeller shaft for an automobile. In order to achieve the required torsional strength of 100 to 400 kgf · m or more in the propeller shaft, a single structure of helical winding of ± 5 ± 30 ° of the reinforcing fiber or ± 5 ± 30 helical winding and ± It is preferable to use a hybrid configuration using a helical winding of 75 to 90 ° in combination. The torsional strength is low even if it is less than ± 5 ° or exceeds ± 30 °. On the other hand, when the angle exceeds ± 30 °, the outer diameter of the main body cylinder becomes large, and it is difficult to arrange the main body cylinder in a limited underfloor space of an automobile. However, reinforcing fibers arranged at other angles may be included, or different types of reinforcing fibers may be included. The winding configuration of the reinforcing fiber is common to a winding configuration in a case where a target twist strength is to be obtained at a joint between the FRP main body cylinder and the metal joint, which will be described later.

As the matrix resin constituting the FRP propeller shaft of the present invention, a thermosetting resin such as an epoxy resin, a phenol resin, a polyimide resin, a vinyl ester resin, and an unsaturated polyester is used. And thermoplastic resins such as polyamide, polycarbonate and polyetherimide.

The reinforcing fibers are not limited to carbon fibers, but may be glass fibers, aramid fibers, or the like, and may be used in combination.

In the FRP propeller shaft for an automobile, the torsion strength of the FRP main body cylinder as described above is ensured, and the torsion strength of 100 to 400 kgf · m or more is also achieved at the joint between the FRP main body cylinder and the metal joint. Required.

In order to satisfy this requirement, a propeller shaft according to the present invention is a propeller shaft in which a metal joint is joined to an end of an FRP main body cylinder by press-fitting. (A) Surface roughness of joint joint surface (B) the thickness of the joint is 2 to 10 mm, (c) the radial press-fit allowance is 0.2 to 0.5 mm, and (d) the reinforcing fiber layer of the main body cylinder is in the direction of the rotation axis. ± 5
(E) Preferably, the thickness of the main body cylinder is 1.5 to 5.0 mm .

The propeller shaft according to the present invention in the case of a hybrid configuration is a propeller shaft in which a metal joint is joined to an end of an FRP main body cylinder by press-fitting. (B) the thickness of the joint joint is 2 to 10 mm, (c) the radial press-fit allowance is 0.2 to 0.5 mm, and (d) the reinforcing fiber layer of the main body tube is ± 5 for rotation axis direction
A hybrid configuration of a helical winding layer of up to ± 30 ° and a circumferential winding layer of ± 75 to 90 °; (e) the thickness of the main body cylinder is 1.5 to 5.0 mm, and the thickness of the helical winding layer is 1 0.3 to 4.3 mm, and the thickness of the circumferentially wound layer is preferably 0.2 to 0.7 mm .

By optimizing the joint between the FRP body cylinder and the metal joint as described above, a sufficient torsional strength can be achieved also at the joint. Further, the fatigue strength at the joint is also improved, so that the joint can be joined with less decrease in the joint strength even after being exposed to a high temperature of about 150 ° C.

It is preferable that a reinforcing layer of FRP is provided at the end of the main body tube outside and / or inside the main body tube. The preferred specifications of the outer reinforcing layer and / or the inner reinforcing layer are such that the reinforcing fiber has a winding angle of ± 75 ° to 90 °, a wall thickness of 2 to 5 mm, and an axial length of 1.1 times the joint length of the joint.
It is about 1.5 times.

The reinforcing fiber bundle used for the reinforcing layer is preferably made of a high-strength yarn. Here, a high-strength yarn refers to a yarn having a breaking elongation of 1.6% or more, preferably 2.0% or more.

By providing the above-mentioned reinforcing layer using such a high-strength yarn, the allowable strain of the FRP main body cylinder at the time of joint press-fitting can be designed to be high, so that the press-fit allowance at press-fitting can be increased. Thus, a joint having higher reliability and higher joint strength can be obtained.

In the propeller shaft of the present invention, a sealing material may be provided at an appropriate position (for example, at the end of each member) between the FRP main body cylinder and the metal joint. As the sealing material, a resin, a ring-shaped elastic body, a film and the like are suitable. By providing such a sealing material, it is possible to more reliably prevent entry of moisture and the like, and prevent corrosion of the joint.

When a metal joint is press-fitted, it is necessary to grip the joint with a press-fitting jig. However, the press-fitting jig is applied to the joint so that it can be securely gripped and the joint is not damaged by press-fitting. It is preferable to provide a locking or engaging portion for the tool. Such a locking or engaging portion can be formed by forming a step portion or a groove portion at an appropriate position on the outer surface of the joint.

In order to reduce the press-fitting of the metal joint as much as possible and to press-fit it efficiently, the following method is effective. The temperature of the joint is lowered, and the temperature of the end of the FRP main body cylinder is raised and press-fitted. An adhesive is used as a lubricant. Use a volatile liquid lubricant that does not remain after press-fitting.

Further, it is possible to adjust the balance after the completion of the propeller shaft by providing a balance weight mounting portion on the metal joint and adding an appropriate balance weight to the mounting portion by welding or the like. If cooling fins are formed around the balance weight attachment part, especially on the joint outer surface at the portion between the balance weight attachment part and the FRP main body tube to be joined, welding at the time of joining the balance weight can be performed. The transmission of heat to the FRP main body cylinder side can be suppressed.

[0031]

FIG. 1 shows a propeller shaft according to an embodiment of the present invention. External reinforcing layers 2 are provided at both ends of the FRP main body cylinder 1, and a metal joint 2 is press-fitted to an end of the FRP main body cylinder 1. An outer reinforcing layer 3 whose axial length is slightly longer than the press-fit portion is provided on the outer periphery of the end of the main body cylinder 1.

FIG. 2 shows an enlarged view of the FRP section in the AA section of FIG. 1, that is, the section orthogonal to the rotation axis of the propeller shaft, and was obtained in Example 1 described below. Things. FIG. 3 similarly shows a cross section of an FRP portion of a propeller shaft obtained in Comparative Example 1 described later.

Example 1 C according to the present invention was obtained by a filament winding method.
A body tube made of FRP was molded. 10 turn / m twisted carbon fiber bundle (“Torayca” M4 manufactured by Toray Industries, Inc.)
0, 12000 filaments), and while impregnating a bisphenol A type epoxy resin containing a curing agent and a curing accelerator, a mandrel having an outer diameter of 70 mm and a length of 1300 mm is set at an angle of ± 14 ° with respect to its axial direction. And wound three layers. The yarn width W after impregnation of the resin was 9.5.
mm, the number of divisions was 23.

While rotating the mandrel around which the carbon fiber bundle was wound, the epoxy resin was cured by heating at 180 ° C. for 6 hours, and the mandrel was pulled out to obtain a main body cylinder 1 made of CFRP having an outer diameter of 75 mm and an inner diameter of 70 mm. This body tube 1
Was cut and removed at both ends, and the metal joint 2 was attached and a torsional torque was applied. As a result, the torsional strength was 240 kgfm. The main body tube was cut along a plane perpendicular to the rotation axis, and the cross section was polished and observed with an optical microscope. As shown in FIG. 2, each reinforcing fiber bundle 4 was adjacent to each other with a clear boundary 5, The outermost reinforcing fiber bundle 4 has a pentagonal shape, and the rest has a hexagonal shape.
The honeycombs were stacked on each other.

Comparative Example 1 A body tube made of CFRP was molded in exactly the same manner as in Example 1 except that untwisted carbon fibers were used. When a torsional torque was applied in the same manner as in Example 1, the torsional strength was 200 kgfm. When the tube was cut at a plane perpendicular to the rotation axis and the cross section was polished and observed with an optical microscope, there was no boundary between the reinforcing fiber bundles, and the reinforcing layers 6 were arranged concentrically. Formed a thin resin layer 7.

[0036]

According to the present invention, in a cross section orthogonal to the rotation axis of the FRP propeller shaft, each reinforcing fiber bundle has a boundary with the adjacent reinforcing fiber bundle, and the boundary is uneven in the radial direction of the propeller shaft. As is clear from the comparison between the above-described embodiment and the comparative example, it is possible to obtain high torsional strength as expected in design.

Also, by applying the optimum conditions shown in the present invention to the press-fitting and joining portion between the end of the FRP main body cylinder and the metal joint, a sufficiently high joining strength can be obtained, and It is possible to sufficiently satisfy the torsional strength required as a propeller shaft.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of an FRP propeller shaft according to an embodiment of the present invention.

FIG. 2 is an enlarged partial sectional view taken along line AA of FIG.

FIG. 3 is a partial cross-sectional view of a conventional (comparative) FRP propeller shaft.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 FRP main body cylinder 2 Metal joint 3 External reinforcement layer 4 Reinforcement fiber bundle 5 Boundary 6 Reinforcement layer 7 Resin layer

(56) References JP-A-4-197740 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16C 3/02 B29C 70/16

Claims (8)

(57) [Claims] In the propeller shaft with claim 1] FRP binding body tube, the body tube, when viewed cross-section perpendicular to the rotation axis, <br/> boundaries extending at least in the circumferential direction between the reinforcing fiber bundles next contact is formed, their boundaries, for the radial direction of the main body tube
A propeller shaft that extends while forming irregularities . Wherein said boundary, even for the circumferential direction of the main body tube extends continuously while forming a <br/> irregularities, according to claim 1 propeller shaft. Wherein the shape of each reinforcing fiber bundle in a cross section perpendicular to the rotation axis is polygonal, the boundary formed between the reinforcing fiber bundle adjacent to each other <br/> physician in the cross section is, both Strengthen
At least two vertices of each polygon of the fiber bundle and between the two vertices
The propeller shaft according to claim 1, wherein the propeller shaft is formed to include one side of the propeller shaft. 4. The propeller shaft according to claim 3, wherein each of the reinforcing fiber bundles has a hexagonal shape. 5. The propeller shaft according to claim 1, wherein the individual reinforcing fiber bundles are twisted. 6. The method according to claim 1, wherein the individual reinforcing fiber bundles have 2-20
6. The propeller shaft according to claim 5, wherein the turns are twisted. 7. A method for manufacturing a propeller shaft having an FRP main body tube, wherein the main body tube is manufactured by twisting each reinforcing fiber bundle and winding the twisted reinforcing fiber bundle around a mandrel. And a method for manufacturing a propeller shaft. 8. A method for manufacturing a propeller shaft having an FRP main body tube, wherein the main tube production process includes: (a) twisting individual reinforcing fiber bundles; and (b) twisting reinforcing fibers. (C) a step of winding a plurality of aligned reinforcing fiber bundles around a mandrel; and (d) a width W of the plurality of reinforcing fiber bundles and a circle when winding the bundle around a mandrel. Number of windings N in the circumferential direction and winding angle θ
And a step of adjusting the relationship between the winding diameter d and the circular constant π such that W × N> πdcos θ is satisfied.