JPH04140514A - Power transmission shaft and manufacture thereof - Google Patents

Abstract

PURPOSE:To restrain the occurrence of fatigue failure while reducing the weight of a connection by providing an outer ring for fastening the outer periphery of a pipe on the outer periphery of the pipe corresponding to both front and rear ends of a yoke fit part. CONSTITUTION:A power transmission shaft is composed of an FRP pipe 1, metal yokes 2 coupled with both ends of the pipe 1 and two metal outer rings 3, 4 interposed between the connections of both. The outer rings 3, 4 are located to firmly fasten the outer periphery of the pipe 1 corresponding to both front and rear ends in a fit part 2a of the yoke 2. Thus, the pipe 2 is firmly fastened by the outer rings 3, 4 to simplify a press fit process and restrain the reduction of a press fit force due to a creep phenomenon or the like. By selecting properly the annular rigidity of two outer rings 3, 4, the flow of shearing stress generated at torque transmission can be properly dispersed to contribute much to the restraint of fatigue failure.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a power transmission shaft and a method for manufacturing the same, and more specifically to a power transmission shaft obtained by combining a plastic pipe and a yoke that are separately constructed. The present invention relates to a shaft and a manufacturing method thereof.

(Prior art) In recent years, due to the demand for lighter power transmission shafts used in vehicles, etc., continuous fiber reinforced plastics (hereinafter referred to as F
The development of a power transmission shaft using a molded body made of FRP (RP) is progressing, but in this case, it is necessary to connect a metal yoke to both ends of the FRP pipe, and various methods have been used for this connection. Efforts have been made. For example, the joint part of an FRP pipe and a yoke may have a circular cross section, an elliptical cross section, or a polygonal cross section that can fit together,
There are methods of adhesive bonding after molding and hardening of RP pipes, press-fit bonding methods, and methods of incorporating the yoke itself or a part of it into a mandrel and rolling it in during filament winding to form FRP pipes. Yes, each has its advantages and disadvantages.

The present invention is an improved method of joining the FRP pipe and the yoke by press-fitting among the above methods.

By the way, in the case of the method of press-fitting a metal yoke into an FRP pipe, the joint part of the FRP pipe is susceptible to fatigue damage due to repeated application of driving force and braking force, and delamination and adhesion between FRP layers. In addition to the problem of easy delamination of layers, looking at metal yokes,
Frequently, fretting occurs due to micro-friction occurring at the joint surface, which may lead to peeling of the adhesive layer. One method for dealing with these problems is to use an outer ring. For example, Utsukai 61-1626
As disclosed in Publication No. 19, after the fitting part of the yoke is press-fitted into the FRP pipe, the pipe around the outer circumference of the fitting part is tightened with an outer ring, so that the joint surface between the pipe and the yoke is tightened. A method has been proposed to make peeling less likely to occur.

(Problem to be solved by the invention) In the case of the above-mentioned known example, after press-fitting the yoke into the pipe,
Since the outer ring is fitted while applying a compressive force to the outer circumference of the pipe that bulged out due to the press-fitting, the press-fitting operation is performed twice at the same location, resulting in delays in the manufacturing process. This may lead to complications, and
There is also a risk of a decrease in press force due to creep phenomenon or the like.

By the way, when the outer ring has a long axial dimension, torque transmission between the pipe and the yoke is concentrated near both the front and rear ends of the yoke fitting part, and other parts do not function effectively. This is a fact, and from this point of view as well, there is a risk that fatigue damage may be insufficiently suppressed. Furthermore, in the case of the above-mentioned known example, a high pressing force is required during assembly, and the weight of the joint between the pipe and the yoke increases, which increases the inertia force during bending vibration.
There is also the problem that vibration and noise characteristics are likely to be impaired.

The present invention has been made in view of the above points, and by providing a plurality of contact surfaces between the outer ring and the pipe in the axial direction, the flow of shear stress generated during torque transmission is made smoother. It is also an object of the present invention to make it possible to easily manufacture a power transmission shaft having such excellent characteristics.

(Means for Solving the Problem) In the invention of claim 1, as a means for solving the above problem, in a power transmission shaft formed by fitting and fixing a fitting portion of a yoke to a plastic pipe, On the outer periphery of the pipe corresponding to both front and rear ends of the yoke fitting part,
An outer ring is provided to tighten the outer circumference of the pipe.

In the invention of claim 2, as a means for solving the above problem, when manufacturing a power transmission shaft by fitting and fixing a fitting portion of a yoke to a plastic pipe, the outer periphery of the pipe is provided with: After setting in advance an outer ring for tightening the outer circumferential portion of the pipe corresponding to both the front and rear ends of the yoke fitting part, the yoke fitting part is press-fitted into the pipe, and the yoke fitting part and the pipe are and the outer ring are integrally combined.

(Function) In the invention of claim I, the following effects can be obtained by the above means.

That is, by providing outer rings that tighten the outer circumference of the pipe corresponding to both the front and rear ends of the yoke fitting portion, the flow of shear stress generated during torque transmission becomes smoother.

In the invention of claim 2, the following effects can be obtained by the above means.

That is, after setting the outer ring in advance to tighten the outer circumference of the pipe corresponding to both the front and rear ends of the yoke fitting part, the fitting part of the yoke is press-fitted into the pipe. At the same time as the outer ring is press-fitted, the pipe is tightened by the outer ring.

(Effect of the invention) According to the invention of claim 1, in the power transmission shaft formed by fitting and fixing the fitting portion of the yoke to the plastic pipe, the power transmission shaft corresponds to both the front and rear ends of the yoke fitting portion. An outer ring is provided on the outer periphery of the pipe to tighten the outer periphery of the pipe to smooth the flow of shear stress generated during torque transmission, thereby reducing the weight at the joint between the yoke and the pipe. This has the excellent effect of suppressing the occurrence of fatigue damage, which has been a problem in the past. Furthermore, since the annular rigidity of the outer ring is relaxed, there is also the effect that the pressing force of the yoke fitting portion can be reduced.

According to the invention of claim 2, when manufacturing the power transmission shaft by fitting and fixing the fitting portion of the yoke to a plastic pipe, both front and rear ends of the yoke fitting portion are attached to the outer periphery of the pipe. After setting in advance an outer ring for tightening the outer peripheral part of the pipe corresponding to the pipe, the yoke fitting part is press-fitted into the pipe, and the three parts, the yoke fitting part, the pipe, and the outer ring, are integrated. Since the yoke fitting part is press-fitted at the same time,
The pipe can be tightened by the outer ring, which has the excellent effect of simplifying the press-fitting process and suppressing a decrease in the press-fitting force due to creep phenomena and the like.

(Examples) Hereinafter, a power transmission shaft and a manufacturing method thereof according to the present invention will be described based on some specific examples with reference to the accompanying drawings.

Embodiment 1 FIGS. 1 and 2 show a power transmission shaft according to Embodiment 1 of the present invention. This embodiment corresponds to the first and second aspects of the invention.

In the case of this embodiment, as shown in FIG. 1, the power transmission shaft A is
It is composed of a pipe 1 made of FRP, a metal yoke 2 connected to both ends of the pipe 1, and two metal outer rings 3 and 4 interposed between the joints of the two. Here, the outer ring 3.4 is positioned to tighten the outer peripheral portion of the pipe l corresponding to both front and rear ends of the fitting portion 2a of the yoke 2. Although only one end is shown in the drawing, the other end also has the same structure.

The power transmission shaft A according to this embodiment is constructed by setting the outer ring 34 in advance at a predetermined position on the outer periphery of the end of the pipe l, and then press-fitting the fitting part 2a of the yoke 2 into the pipe l. Fitting part 2a, pipe 1 and outer ring 3
．． It is manufactured by integrally combining three parts, and the process will be explained in detail below.

First, the pipe l is molded and hardened by a known technique such as filament winding, and at least the part where the outer ring 3.4 is inserted (in other words, the fitting part 2a of the yoke 2 is press-fitted) The outer circumferential surface of the outer ring 3 is made into a substantially perfect circle and smooth surface by grinding or turning to ensure close contact with the outer rings 3 and 4.

Next, as shown in FIG. 3, 4 inner peripheral surface or (and) pipe l
By applying adhesive to the outer circumferential surface of the pipe, voids, cracks, lathes, etc. on the outer circumferential surface of the pipe will be filled, and the yoke will
Tightening in the radial direction after press-fitting the fitting portion 2a is convenient because the surface pressure distribution is averaged with respect to the force. In addition, if the outer rings 3, 4 and the pipe l are adhesively bonded in advance (that is, the adhesive is hardened), even if the two are a loose fit, the appearance will be good and there will be no gap. Therefore, the press-fitting effect is effectively exerted when the yoke fitting portion 2a is press-fitted, which is more convenient. Note that the fitting between the outer rings 3 and 4 and the pipe 1 may be an interference fit.
Even in this case, it is advantageous to apply an adhesive to increase the bonding strength.

Next, the fitting part 2a of the yoke 2 is press-fitted into the pipe 1 as shown in FIG. 2, and the pipe 1, the yoke fitting part 2a, and the outer rings 3, 4 are combined into a three-part body. .

As described above, in this embodiment, after the outer rings 3 and 4 are set in advance around the outer periphery of the end of the pipe 1, the yoke fitting part 2a is press-fitted into the pipe 1. At the same time as the yoke fitting portion 2a is press-fitted, the outer rings 3 and 4 are tightened to the pipe 2, which simplifies the press-fitting process and suppresses a decrease in press force due to creep phenomena and the like.

In addition, in the case of this embodiment, two outer rings 3.4 having short axial dimensions are used to connect the pipe l and the yoke fitting part 2a.
This makes it possible to reduce the force required to press-fit the yoke fitting portion 2a compared to the case where an outer ring with a long axial dimension is used as in the conventional example. .

Furthermore, if the annular rigidity of the two outer rings 3.4 is appropriately selected, it will be possible to effectively disperse the flow of shear stress generated during torque transmission, which will greatly contribute to suppressing fatigue damage. . A method to make this more effective is to use a steel ring as the outer ring 3 inserted at the end of the pipe l, and use an aluminum ring as the outer ring 4 located in the middle, so that the tightening force is lower. Alternatively, both outer rings 3 and 4 are made of the same material,
Possible methods include changing the wall thickness and axial dimensions to lower the tightening force for the middle outer ring 4.

In this embodiment, the machined part of the pipe 1 that serves as the outer ring insertion part is stepped, and the end part of the pipe 1 has a small diameter, but this is not necessarily necessary, and Two outer rings 3, 4 on the diameter
You may also insert .

Embodiment 2 FIGS. 3 and 4 show a power transmission shaft according to Embodiment 2 of the present invention. This embodiment corresponds to the first and second aspects of the invention.

In the case of this embodiment, the outer ring 3 inserted into the end side of the pipe l has an extended portion 3a obtained by extending its outer end.
Serrations 5 are formed on the inner peripheral surface of the extended portion 3a. On the other hand, the yoke 2 has a fitting part 2.
Serrations 6 are formed following a. Reference numeral 7 denotes a circumferential groove formed on the outer periphery of the proximal end portion of the extension portion 3a in the outer ring 3.

In the case of this embodiment, the power transmission shaft A is manufactured as follows.

The steps up to inserting and fixing the outer ring 3.4 into the pipe 1 are the same as those in the first embodiment described above, so a description thereof will be omitted.

After inserting and fixing the outer ring 3.4 in a predetermined position of the pipe l in the same manner as in Example 1, the fitting part 2a of the yoke 2 is press-fitted into the pipe l, and then the extending part 3a of the outer ring 3 and the yoke are The outer ring 3 and the yoke 2 are coupled by cold plastic working such as roll working, press working, or electromagnetic caulking so that the outer ring 3 and the yoke 2 can rotate together. In the case of this embodiment, the serrations 5 of the outer ring extension portion 3a and the serrations 6 of the yoke 2 are engaged with each other, so that the two are firmly coupled. In addition,
At this time, the groove 7 formed on the outer peripheral surface of the outer ring 3
is the caulked part (i.e., plastically deformed part) of the outer ring 3
This makes it easy to plastically deform the pipe 1, and prevents the vicinity of the end of the pipe 1 from breaking due to this owner shear stress.

In the case of this embodiment, after the yoke fitting part 2a is press-fitted, the Moeki outer ring extension part 3a and the yoke 2 are connected so that they can rotate together, so that torque is transmitted between the yoke 2 and the pipe l. This is done not only from the inner peripheral surface of the pipe 1 but also from the outer peripheral surface via the outer ring 3. In particular, torque transmission from the outer circumferential surface of the pipe l via the outer ring 3 can be achieved with low shear stress due to the difference in radius from the inner circumferential surface. Compared to torque transmission, it is possible to significantly suppress the degree of fatigue damage caused by micro-friction occurring at joint surfaces, glabellar peeling in FRP pipes, and the like. In addition, it is possible to reduce the pressing force, and since the outer ring 3 exerts a stiffening effect against the force in the bending direction between the pipe l and the yoke 2, it also contributes to improving bending rigidity. becomes.

In the above embodiment, the outer ring extension portion 3a and the yoke 2
The overlapping parts of the yoke fitting part 2a are plastically deformed and connected after the yoke fitting part 2a is press-fitted.
It is also possible to make the plastic deformation connection at the same time as the press-fitting. However, in this case, the pressing force is likely to be excessive <FRP
Care must be taken when press-fitting as this may cause damage to the manufactured pipe l.

In addition to the above embodiments, methods for joining the outer ring extension portion 3a and the yoke 2 so as to rotate together include a method of welding the overlapping portions of the two at a relatively low temperature such as electron beam welding; Possible methods include mechanical coupling using rivets.

Furthermore, regular irregularities such as serrations may be formed only on the outer periphery of the yoke 2, or the outer periphery of the yoke 2 may have a polygonal shape.

Note that the joint surface between the outer ring extension portion 3a and the yoke 2 is not only straight as in this embodiment, but also tapered or semi-cylindrical so that the diameter becomes smaller toward the mating part side or the opposite mating part. You can also use it as

The other configurations and effects are the same as those of the first embodiment described above, so their explanations will be omitted.

Embodiment 3 FIGS. 5 and 6 show a power transmission shaft according to Embodiment 3 of the present invention. This embodiment corresponds to the first and second aspects of the invention.

In the case of this embodiment, the outer rings 3 and 4 are integrally connected via an annular connecting body 8, and each inner peripheral surface has serrations 9. lO is formed. In this embodiment, a gap is formed between the connecting body 8 and the outer peripheral surface of the pipe l.

With this configuration, in the case of this embodiment, it is possible to omit machining the outer diameter of the pipe I.

That is, when the outer ring 3.4 is inserted, the serrations 9.4 formed on the inner peripheral surface thereof. Since the convex portion that would otherwise be formed on the outer diameter of the pipe 1 can be mechanically shaved off by IO, there is no need for outer diameter machining.

Note that the diameters of the serrations 910 of the outer rings 3 and 4 may be the same diameter or may be slightly different, but in the latter case, the pipes are inserted so that the middle side of the pipe 1 is the larger diameter side. Ru.

The other configurations and effects are the same as those of the first embodiment described above, so their explanations will be omitted.

Embodiment 4 FIGS. 7 and 8 show a power transmission shaft according to Embodiment 4 of the present invention. This embodiment corresponds to the first and second aspects of the invention.

In the case of this embodiment, the outer ring 3 in embodiment 2,
4 are connected by a connecting body 8, and other configurations and effects are the same as in the second embodiment.

In each of the above embodiments, the pipe is made of FRP, but it may also be made of other plastics.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view of a power transmission shaft according to Embodiment 1 of the present invention, FIG. 2 is an intermediate process diagram for manufacturing the power transmission shaft shown in FIG. 1, and FIG. 3 is an implementation of the present invention. FIG. 4 is a partially cutaway cross-sectional view of the power transmission shaft according to Example 2.
An intermediate process diagram in the case of manufacturing the power transmission shaft shown in the figure, FIG. 5 is a partial half-cut sectional view of the power transmission shaft according to Embodiment 3 of the present invention, and FIG. 6 is a diagram of manufacturing the power transmission shaft shown in FIG. 5. FIG. 7 is a partial cross-sectional view of a power transmission shaft according to Embodiment 4 of the present invention, and FIG. 8 is an intermediate process diagram when manufacturing the power transmission shaft shown in FIG. 7. . l...Pipe 2...Yoke 2a...Fitting part 3.4...Outer ring

Claims (1)

[Scope of Claims] 1. A power transmission shaft formed by fitting and fixing a fitting portion of a yoke to a plastic pipe, wherein a power transmission shaft is provided on the outer periphery of the pipe corresponding to both front and rear ends of the yoke fitting portion. teeth,
A power transmission shaft characterized by being provided with an outer ring that tightens the outer circumference of the pipe. 2. When manufacturing a power transmission shaft by fitting and fixing a fitting part of a yoke to a plastic pipe, a part of the pipe outer circumference corresponding to both front and rear ends of the yoke fitting part is attached to the outer circumference of the pipe. After setting an outer ring for tightening in advance, the yoke fitting part is press-fitted into the pipe to integrally connect the yoke fitting part, the pipe, and the outer ring. A method for manufacturing a power transmission shaft.