JP4114022B2 - Power transmission shaft - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power transmission shaft provided with universal joints at both ends of an intermediate shaft portion.
[0002]
[Prior art]
A power transmission shaft used as a propeller shaft of an automobile has a universal joint including a cross bearing at both ends of an intermediate shaft portion. Further, 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]
[Problems to be solved by the invention]
When the power transmission shaft as described above is rotating at a high speed, the intermediate shaft portion bends in the same manner as a beam supported at both ends due to an unbalanced load or mechanical vibration of the transmission shaft itself. In the vicinity where the number of rotations per second of the shaft matches 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 dangerous rotational speed, it is necessary to increase the rigidity of the intermediate shaft portion or increase the natural frequency of the shaft by reducing the weight. Normally, a method of increasing the outer diameter of the intermediate shaft portion made of a pipe material without changing the plate thickness is adopted, but this method causes a space limitation and avoids a considerable increase in weight. There is a problem that can not be.
[0004]
An object of the present invention is to provide a power transmission shaft having a structure capable of increasing the dangerous rotational speed without increasing the outer diameter of the intermediate shaft portion and without increasing the weight so much.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the power transmission shaft of the present invention is a power transmission shaft in which universal joints are provided at both ends of an intermediate shaft portion made of a pipe, and the intermediate shaft portion is disposed inside the pipe of the intermediate shaft portion. It is characterized by incorporating a reinforcing beam in which a plurality of fins are arranged radially and are integrated with each other around the axis. 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.
[0006]
Here, in the present invention, it is possible to adopt a configuration in which the reinforcing beam is made of an integrally formed synthetic resin and extends in the longitudinal direction together with the pipe (claim 2).
[0007]
In the present invention, a configuration in which the diameter of the predetermined portion at both ends is larger than the diameter of the predetermined portion at both ends (Claim 3) can be adopted.
[0008]
Further, in the present invention, the number of fins of the reinforcing beam is arbitrary, but it is desirable that at least three or more.
The present invention seeks to improve the bending rigidity of the intermediate shaft portion during natural vibration of the shaft by incorporating a reinforcing beam into the pipe of the intermediate shaft portion. That is, when the pipe of the intermediate shaft portion is bent due to natural vibration, the amount of bending of the pipe falls below a certain limit due to contact with any one or a plurality of fin tips constituting the reinforcing beam incorporated therein. It is suppressed.
[0009]
Specifically, for example, when a power transmission shaft with a center-to-core distance L (see FIG. 2) = 1500 mm and the intermediate shaft has an outer diameter of 110 mm, an inner diameter of 100 mm, and a length of about 1200 mm, the pipe is in resonance. In this case, a flexural vibration of about 10 mm occurs in the entire vibration width. If a reinforcing beam is incorporated in the pipe, both of them come into contact when the pipe is bent by an amount corresponding to the gap between the inner peripheral surface of the pipe and the fin tip of the reinforcing beam. The gap between the pipe inner peripheral surface and the fin tip 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 bending vibration amplitude of the pipe of about 10 mm, and the bending rigidity of the reinforcing beam itself. Is set to a certain level or more, the bending rigidity of the intermediate shaft portion is substantially improved, and the dangerous rotational 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 limitation, and since it has a shape in which a plurality of fins protrude radially from the axis, The weight of the intermediate shaft portion does not increase so much.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is an exploded perspective view of an embodiment of the present invention, in which a portion excluding both ends of the pipe 11 is omitted, and FIG. 2 is shown in a state in which a tip portion is omitted from the cross bearings 23 and 32. It is sectional drawing. Known universal joints 2 and 3 are respectively provided at both ends of the intermediate shaft portion 1. One universal joint 2 includes 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 yoke 23 to the sleeve yoke 22. The cylindrical hole yoke 24 connected together is a main component. The other universal joint 3 is mainly composed of a weld yoke 31 welded to the pipe 11 of the intermediate shaft portion 1 and a cylindrical hole yoke 33 connected to the weld yoke 31 via a cross bearing 32.
[0011]
A reinforcing beam 12 is incorporated in the pipe 11 of the intermediate shaft portion 1. In this example, the reinforcing beam 12 is an integrally molded product of synthetic resin, and as shown in the cross-sectional view perpendicular to the axis in FIG. 3, the six fins F are arranged radially at equal angles around the axis. Have a structure. The engagement relationship between the reinforcing beam 12 and the pipe 11 is a state in which the reinforcing beam 12 is fixed to each other by being press-fitted into the inner diameter surface of the pipe 11. More specifically, the reinforcing beam 12 has press-fit portions 12a and 12b whose diameters (heights of the fins 12) at both end portions of a predetermined length are larger than those in other regions. Only the press-fitted portions 12a and 12b at both ends are press-fitted into the pipe 11, and in other portions, a slight gap is formed between the inner peripheral surface of the pipe 11 and the assembling work is facilitated. Yes.
[0012]
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 predetermined with respect to the welded portion W between the pipe 11 and the spline shaft 21 and the pipe 11 and the weld yoke 31. It is located a distance away. This is because when the reinforcing beam 12 is press-fitted into the pipe 11 and the spline shaft 21 and the weld yoke 31 are welded to both ends of the pipe 11, the influence of the welding heat reaches the resin reinforcing beam 12. This is to prevent it.
[0013]
According to the above-described embodiment of the present invention, even if the rotational speed of the shaft is in the vicinity of the resonant rotational speed of the pipe 11 and the pipe 11 tends to be greatly bent, the inner peripheral surface of the pipe 11 is the reinforcing beam 12. Since the fin F is in contact with the fin F, its bending amount 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 portion 1 as a whole increases. The critical rotational speed of is substantially increased.
[0014]
Here, since the pipe 11 in this type of power transmission shaft is normally used without particularly machining a drawn steel pipe or the like, it is expected that the inner diameter dimension is not uniform. Since the amount of shaft deflection at the rotational speed reaches several millimeters or more, as long as the reinforcing beam 12 is securely press-fitted into the pipe 11 at both ends thereof, the pipe 11 and the reinforcing beam at other portions. Even if the gap between the two 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. However, the present invention is not limited to this, and for example, a steel plate integrated by welding or the like is also used. Of course you can. In this case, it is not necessary to provide a distance between both ends of the reinforcing beam 12 and the welded portions W at both ends of the pipe 11. Further, the number of fins F of the reinforcing beam 12 is not limited to six, and can be any number of three or more as long as necessary bending rigidity can be obtained.
[0015]
【The invention's effect】
As described above, according to the present invention, a reinforcing beam in which a plurality of fins are radially arranged and integrated is incorporated into a pipe constituting an intermediate shaft portion of a power transmission shaft having universal joints at both ends. Therefore, the critical shaft speed can be increased by increasing the bending rigidity of the intermediate shaft portion without increasing the diameter of the intermediate shaft portion and without significantly increasing the weight.
[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 cross bearings at both ends of a pipe.
FIG. 3 is an axial cross-sectional view of a reinforcing beam according to the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Intermediate shaft part 11 Pipe 12 Reinforcing 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 (3)

In a power transmission shaft provided with universal joints at both ends of an intermediate shaft portion made of a pipe, a plurality of fins are radially arranged around the axis of the intermediate shaft portion inside the pipe of the intermediate shaft portion. An integrated reinforcing beam is incorporated, and both ends of the reinforcing beam are press-fitted into the inner peripheral surface of the pipe, and portions other than the predetermined portions at both ends and the inner peripheral surface of the pipe A power transmission shaft characterized in that a gap is formed between them . The power transmission shaft according to claim 1, wherein the reinforcing beam is made of an integrally molded synthetic resin and extends in the longitudinal direction together with the pipe. 3. The power transmission shaft according to claim 1, wherein a diameter of the predetermined portion on both ends is larger than a diameter other than the predetermined portion on both ends.

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