JPH11303845A - Power transmitting shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise the critical number of revolution while improving the bending rigidity of an intermediate shaft part by assembling a reinforcing beam integrated with radially arranged plural fins in a pipe forming an intermediate shaft part of a power transmitting shaft. SOLUTION: A reinforcing beam 12 is assembled in a pipe 11 of an intermediate shaft part 1. Length of the reinforcing beams 12 is shorter than the length of the pipe 11, and both ends of the reinforcing beams 12 are positioned while separated by the predetermined distance from a welding-contact part of the pipe 11 and a spline shaft 21, and the pipe 11 and a weld yoke 31. Consequently, the number of revolution of the shaft comes close to the number of resonant revolution of the pipe 11, and even in the case where the pipe 11 is being deflected more, since the inner peripheral surface of the pipe 11 contacts with a fin F of the reinforcing beam 12, the deflected quantity is regulated to the quantity corresponding to a clearance between the reinforcing beam 12 at a central part of the pipe 11, and the bending rigidity of the whole of the intermediate shaft part 1 is improved so as to practically raise the critical number of revolution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission shaft having universal joints at both ends of an intermediate shaft.

[0002]

2. Description of the Related Art A power transmission shaft used as a propeller shaft of an automobile has a universal joint including cross bearings at both ends of an intermediate shaft portion. As the intermediate shaft portion, a pipe called a propeller tube or the like is usually used for the purpose of weight reduction or the like.

[0003]

In such a power transmission shaft as described above, when rotating at a high speed, an unbalanced load or mechanical vibration of the transmission shaft itself causes a beam supported at both ends on the intermediate shaft portion. The same bending occurs. In the vicinity where the number of rotations per second of the shaft coincides with the natural frequency of bending of the intermediate shaft portion, the bending strain of the intermediate shaft portion becomes extremely large due to resonance, and in the worst case, breakage may occur. . In order to increase such a critical rotation speed, it is necessary to increase the rigidity of the intermediate shaft portion or to increase the natural frequency of the shaft by reducing the weight. Usually, the outer diameter of the intermediate shaft made of pipe material is increased without changing its thickness.However, this method creates restrictions on space and other factors, and avoids a considerable increase in weight. There is a problem that can not be.

[0004] It is an object of the present invention to provide a power transmission shaft having a structure capable of increasing the critical rotation speed without increasing the outer diameter of the intermediate shaft portion and without increasing the weight significantly. It is in.

[0005]

In order to achieve the above object, a power transmission shaft according to the present invention is a power transmission shaft having a universal joint provided at both ends of an intermediate shaft portion made of a pipe.
It is characterized in that a reinforcing beam in which a plurality of fins are radially arranged around the axis of the intermediate shaft portion and integrated with each other is incorporated in the pipe of the intermediate shaft portion. Here, in the present invention, the material of the reinforcing beam is not particularly limited, and for example, a steel plate or a resin molded product can be used.

In the present invention, the number of fins of the reinforcing beam is arbitrary, but it is preferable that the number of fins is at least three. The present invention is intended to improve the bending rigidity of the intermediate shaft during natural vibration of the shaft by incorporating a reinforcing beam into the pipe of the intermediate shaft. That is, when the pipe of the intermediate shaft bends due to natural vibration, the amount of deflection of the pipe is less than a certain limit due to contact with one or more fin tips constituting the reinforcing beam incorporated therein. Is suppressed.

Specifically, for example, a power transmission shaft having a center-to-center distance L (see FIG. 2) of 1500 mm, and a pipe of an intermediate shaft portion having an outer diameter of 110 mm, an inner diameter of 100 mm, and a length of 1200 mm
In this case, a flexural vibration of about 10 mm is generated in the pipe at the time of resonance at the full vibration width. If the reinforcing beam is incorporated in the pipe, the pipe and the reinforcing beam are in contact with each other when the pipe is bent by an amount corresponding to the gap between the inner peripheral surface of the pipe and the tip of the fin of the reinforcing beam. The gap between the inner peripheral surface of the pipe and the tip of the fin of the reinforcing beam is set to an appropriate amount or less, for example, about 1 mm or less in relation to the above-described deflection vibration amplitude of the pipe of about 10 mm, and the bending rigidity of the reinforcing beam itself. Is set to a certain degree or more, the bending rigidity of the intermediate shaft portion is substantially improved, and the critical rotation speed of the power transmission shaft can be increased. And, since the reinforcing beam in the present invention is incorporated in the pipe of the intermediate shaft portion, there is no space restriction, and since it has a shape in which a plurality of fins project radially from the axis, The weight of the intermediate shaft does not increase too much.

[0008]

FIG. 1 is an exploded perspective view of an embodiment of the present invention, in which parts other than both ends of a pipe 11 are omitted, and FIG.
FIG. 3 is a cross-sectional view showing a state where a tip portion is omitted from FIG. Known universal joints 2 and 3 are provided at both ends of the intermediate shaft portion 1, respectively. One universal joint 2 has a spline shaft 21 welded to one end of a pipe 11 constituting the intermediate shaft portion 1, a sleeve yoke 22 into which the spline shaft 21 is inserted, and a cross bearing 23 with respect to the sleeve yoke 22. Cylindrical yoke 24 connected
Is the main component. Also, the other universal joint 3
Is a weld yoke 31 welded to the pipe 11 of the intermediate shaft portion 1, and a cross bearing 3
The main component is a cylindrical hole yoke 33 that is connected through the second through hole 2.

In the pipe 11 of the intermediate shaft portion 1, a reinforcing beam 1 is provided.
2 are incorporated. In this example, the reinforcing beam 12 is an integrally molded product of a synthetic resin, and six fins F are radially arranged at an equal angle around the axis as shown in FIG. It has a structure. The engagement relationship between the reinforcing beam 12 and the pipe 11 is fixed to each other by press-fitting the reinforcing beam 12 into the inner diameter surface of the pipe 11. More specifically, the reinforcing beam 12 has press-fit portions 12a and 12b in which the diameter (height of the fin 12) at a predetermined length at both ends is larger than that of other regions. Press-fit portions 12 at both ends
a and 12b are pressed into the pipe 11 only,
In other portions, a slight gap is formed between the pipe 11 and the inner peripheral surface, thereby facilitating the assembling work.

The length of the reinforcing beam 12 is shorter than the length of the pipe 11, and both ends of the reinforcing beam 12 are connected to the welded portions W between the pipe 11 and the spline shaft 21 and between the pipe 11 and the weld yoke 31. It is located a predetermined distance away from it. This is because, after the reinforcing beam 12 is press-fitted into the pipe 11, the spline shaft 2 is attached to both ends of the pipe 11.
This is to prevent the influence of the welding heat from affecting the resin-made reinforcing beam 12 when welding the first and weld yokes 31.

According to the above embodiment of the present invention, even if the rotation speed of the shaft is close to the resonance rotation speed of the pipe 11 and the pipe 11 is largely bent, the inner peripheral surface of the pipe 11 is used for reinforcement. Since the beam 12 comes into contact with the fin F, the amount of bending thereof is regulated to an amount corresponding to the gap between the reinforcing beam 12 and the central portion of the pipe 11, and the bending rigidity of the intermediate shaft 1 as a whole increases. Thus, the critical rotation speed of the shaft is substantially increased.

Here, since the pipe 11 in this type of power transmission shaft is usually used without particularly machining a drawn steel pipe or the like, it is expected that the inner diameter of the pipe 11 will not be uniform. In addition, since the amount of deflection of the shaft at the critical rotational speed reaches several mm or more, as long as the reinforcing beam 12 is securely pressed into the pipe 11 at both ends, the other portion of the shaft is not connected to the pipe 11. Even if the gap between the reinforcing beam 12 and the reinforcing beam 12 is large to some extent, the above effect can be obtained. In the above embodiment, an integrally molded resin product is used as the reinforcing beam 12,
The present invention is not limited to this, and it is a matter of course that a steel plate integrated by welding or the like can be used. In this case, both ends of the reinforcing beam 12 and the pipe 11
It is not necessary to provide a distance between the welded portions W at both ends. Further, the number of the fins F of the reinforcing beam 12 is not limited to six, and may be any number of three or more as long as necessary bending rigidity can be obtained.

[0013]

As described above, according to the present invention, a plurality of fins are radially arranged and integrated inside a pipe constituting an intermediate shaft portion of a power transmission shaft having universal joints at both ends. Since the reinforcing beam is incorporated, the bending rigidity of the intermediate shaft can be increased without increasing the diameter of the intermediate shaft and without increasing the weight significantly, and the dangerous rotation speed can be increased. it can.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an embodiment of the present invention, in which a central portion of a pipe is omitted.

FIG. 2 is a cross-sectional view of the embodiment of the present invention, in which a tip portion is omitted from a cross bearing at both ends of a pipe.

FIG. 3 is a cross-sectional view orthogonal to the axis of the reinforcing beam according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Intermediate shaft part 11 Pipe 12 Reinforcement beam 2, 3 Universal joint 21 Spline shaft 22 Sleeve yoke 23, 32 Cross bearing 24, 33 Cylindrical hole yoke 31 Weld yoke F Fin W Welded part

Claims (1)

[Claims] 1. A power transmission shaft provided with universal joints at both ends of an intermediate shaft portion made of a pipe, wherein a plurality of fins are radially formed around the axis of the intermediate shaft portion inside the pipe of the intermediate shaft portion. A power transmission shaft including a reinforcing beam arranged and integrated with each other.