JP2003247561A - Universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress generation of rotation unbalance of a propeller shaft by preventing looseness between a bottom of a bearing cup and a tip of a cross shaft. <P>SOLUTION: A universal joint is composed in such a manner that an input shaft yoke 12 and an output shaft yoke which are respectively provided at each opposite end of an input shaft and an output shaft are connected by the cross shaft 15. At the same time, the bearing cup 22 of a needle bearing 16 is held inside a holding hole 18 formed at both tips 12a in a forked shape of each yoke, and each tip 15b of the cross shaft is supported freely rotatably to each yoke via the needle bearing. Rigidity in the opening direction of the tip of the input shaft yoke is set smaller than the rigidity of the bottom 22b of the bearing cup by setting at about 13.0 kN/mm, and an initial load in the axial direction is imparted to a space in-between a tip face of a protruded part 27 of the bottom of the bearing cup with which the tip face of a protrusion 21 of the tip 15b of the cross shaft is brought into contact. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a universal joint applied to a power transmission mechanism from a transmission to a final reduction gear for driving power of a vehicle engine, and more particularly to a bearing cup by an input load from an input shaft yoke. The present invention relates to a universal joint capable of preventing an excessive load in the axial direction from being generated between the bottom of the shaft and the tip of the cross shaft.

[0002]

2. Description of the Related Art As is well known, various universal joints such as hook type (cardan type) and double cardan type are used for a power transmission mechanism from a vehicle steering mechanism or transmission to a final reduction gear. As one of them, there is one as shown in FIG. 5 (see JP 2001-12490 A, etc.).

In brief, this universal joint is a cardan joint, and in the figure, only the main part on the input shaft yoke side is shown. That is, the input shaft yoke 1 is provided at one end of the input shaft, while the output shaft yoke facing the input shaft yoke 1 is provided at one end of the output shaft (not shown). A cross shaft 2 is rotatably interposed via a needle bearing 3 between the input shaft yoke 1 and the output shaft yoke.

The input shaft yoke 1 has a substantially U shape, and the holding holes 4 are formed through the respective tip portions 1a of the input shaft yoke 1, while the output shaft yoke also has a substantially U shape. A holding hole is formed therethrough.

Further, the cross shaft 2 is provided with the needle bearings 3 which are inserted into and held in the holding holes 4 at the respective tip portions 2a.

The needle bearing 3 has a substantially bottomed cylindrical bearing cup 5 which is press-fitted into and held in the inner peripheral surface of each holding hole 4, and the inner peripheral surface of the bearing cup 5 and the tip of the cross shaft 2. The needle roller 6 is interposed between the needle roller 6 and the portion 2a. Further, a minute gap is formed between the needle roller 6 and the inner peripheral surface of the bearing cup 5 and the outer peripheral surface of the tip portion 2a of the cross shaft 2 in order to ensure smooth rotation of each needle roller 6. Has been done.

The tip portion 1a of the input shaft yoke 1
The width W in the radial direction is set to be relatively large so that the rigidity is sufficiently large, and almost the entire portion including the bottom portion 5a of the bearing cup 5 is inserted into the holding hole 4.

When the bearing cup 5 is assembled with the cross shaft 2 or the like, the cross cup 2 is formed on the bottom surface 5b of the bottom portion 5a.
The tip surface 2b of the tip portion 2a is in contact with the bottom surface 5b by a snap ring 8 fitted in a ring groove 7 formed at the base end portion on the opposite side of the bottom portion 5a.
The movement of the tip end surface 2b of the cross shaft in the axial direction is restricted by the axial pressing force.

The input torque transmitted to the input shaft yoke 1 in accordance with the rotational driving of the input shaft is input to the needle bearings 3 on the input shaft side from the respective tip portions 1a, and from here, the respective tip portions of the cross shaft 2 are provided. 2a, and is further transmitted from the tip end portion of the output shaft yoke to the output shaft through the needle bearing on the output shaft side.

[0010]

The cardan type universal joint is a so-called shell type in which a bearing cup is swaged and fixed to a yoke, and the bearing cup 5 as in the conventional example is attached to the yoke 1. In contrast, there is a so-called solid type that is fixed by a snap ring 8 or the like. This solid type has sufficient strength even if the bearing cup 5 is formed by cutting and the ring groove 7 is formed as described above. In order to maintain the same, the wall thickness is set to be relatively large so that the overall rigidity including the bottom portion 5b is increased.

However, when the universal joint has a bending angle, the tip portion 2a of the cross shaft 2 has the bearing cup 5
Since the bottom surface 5b of the bearing cup 5 slides while abutting the bottom surface 5c of the bearing cup 5 in the axial direction, a concentrated load is generated between the two and the bottom surface 5c of the bearing cup 5 having a rigidity smaller than that of the cross shaft 2 is aged. There is a possibility that it will be worn out and axial play will occur between the two.

Therefore, after long-term use, the bottom surface 5 is
A gap due to wear is formed between c and the front end surface 2b of the cross shaft 2, and the axial center of the cross shaft 2 may be deviated from the center axis of the bearing cup 5 due to this gap. .

As a result, the rotational balance of the propeller shaft is lost during transmission of rotational drive, and vibration and noise are likely to occur.

In particular, since the solid type has a high rigidity, if the bearing cup 5 is firmly fixed in the axial direction of the tip portion 2a of the cross shaft 2, the cross shaft tip portion 2a is formed.
Since the friction between the bottom surface 5c and the bottom surface 5c cannot be firmly fixed, the rattling is more likely to occur.

[0015]

The present invention has been devised in view of the technical problem of the conventional solid type universal joint, and the invention according to claim 1 particularly relates to the tip of each yoke. The rigidity in the opening direction of the bearing cup is set to be smaller than the rigidity of the bottom portion of the bearing cup. The feature is that an axial initial load is applied between them.

Therefore, according to the present invention, for example,
When the rotational driving torque is transmitted from the propeller shaft to the input shaft yoke, a spring action is exerted on both end portions of the input shaft yoke, which have relatively low rigidity, to suppress rapid torque transmission to the bearing cup. Therefore, abrupt contact between the bottom surface of the bearing cup and the tip surface of the cross shaft is prevented.

The invention according to claim 2 is characterized in that the opening rigidity of the tip portion of the yoke is set to 4 to 31 KN / mm.

According to a third aspect of the present invention, the yoke is formed by press forming.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a universal joint according to the present invention will be described below in detail with reference to the drawings. In each of the embodiments, the universal joint is applied to the propeller shaft that transmits the driving force of the vehicle engine from the transmission to the final reduction gear.

FIG. 2 shows a first embodiment of the present invention. This universal joint is a cardan type joint as in the conventional case.
An input shaft yoke 12 is provided at one end of an input shaft 11 on the transmission side, while an output shaft yoke 1 facing the input shaft yoke 12 is provided at one end of an output shaft 13 on the final reduction gear unit side.
4 are provided. A cross shaft 15 is rotatably interposed between the input shaft yoke 12 and the output shaft yoke 14 via needle bearings 16 and 17.

As shown in FIG. 1, the input shaft yoke 12 is bent into a substantially U-shape by a press material, and a circular holding hole 18 is formed through each tip 12a. The output shaft yoke 14 is also formed into a substantially U shape by a press material, and a circular holding hole 19 is formed through each tip 14a.

The width W1 of the input shaft yoke 12 and the output shaft yoke 14 including the tip portions 12a and 14a thereof is set to be sufficiently thin as compared with the conventional one, and the arrangement thereof. Is set inside the bearing cup 22, that is, closer to the intersection 15 a side of the cross shaft 15.

The cruciform shaft 15 has four tip portions 15b integrally projecting at a position of 90 ° around the central intersection portion 15a, and the holding holes 18, 18 are formed in the tip portions 15b. The needle bearings 16 and 17 which are inserted and held in 19 are attached. Each of the tip portions 15b
Is an annular flange 20 at the base end on the side of the intersection 15a.
Is integrally formed, and a circular protrusion 21 is integrally provided at the center position of the tip end surface as shown in FIG.

For convenience, the needle bearings 16 and 17 will be described on the input shaft yoke 12 side.
As shown in FIG. 1, a substantially bottomed cylindrical bearing cup 22 is inserted and held in each of the holding holes 18, an inner peripheral surface of the bearing cup 22, and a tip portion 15 of the cross shaft 15.
a plurality of needle rollers 2 interposed between the outer peripheral surface of b
3 and 3.

The bearing cup 22 has an axial length set relatively long to secure the length of the needle roller 23, and the width length of the tip portion 12a of the input shaft yoke 12 is set as described above. Is relatively thin, the base end 22 on the side of the intersection 15a of the cross shaft 15 is formed.
While the a side is inserted and held in the holding hole 18 of the input shaft yoke tip portion 12a, the holding hole 1 is provided on the bottom 22b side.
It projects outward from 8 and is not held by the tip portion 12a.

Further, the cross shaft 15 of the bearing cup 22
A substantially annular fitting groove 25 for fitting and holding the snap ring 24 is formed on the inner peripheral surface on the side. The snap ring 24 is for positioning and fixing the yoke 12 in the axial direction (outward direction) when the bearing cup 22 is inserted into the holding hole 18 of the yoke 12.

Further, the inner peripheral surface 2 of the bearing cup 22
A seal ring 26 that seals the inside is interposed between an annular groove formed near the inner opening end of 2a and the flange portion 20 of the cross shaft tip portion 15b. Further, in this bearing cup 22, a convex portion 27 that comes into contact with the protrusion 21 of the tip portion 15b is integrally provided on the bottom surface of the bottom portion 22b.

As shown in FIG. 1, each of the needle rollers 23 is rotatably held between the outer peripheral surface of the tip portion 15b and the inner peripheral surface of the bearing cup 22 with a minute gap therebetween, and its length. Is set to be relatively long corresponding to the length of the bearing cup 22, and each one end portion 23a thereof located on the bottom portion 22b side of the bearing cup 22 is projected sufficiently outward from the position of the holding hole 18. It is in the position.

Further, in the input shaft yoke 12, as shown in FIG. 3, the rigidity (solid line G) in the opening direction of the both end portions 12a is sufficiently larger than the opening rigidity of the both end portions of the prior art (one-dot chain line G1). The rigidity is set to be small, and is sufficiently smaller than the rigidity (G2) of the bearing cup 22 on the side of the bottom portion 22b. That is, in this embodiment, when the rigidity value of the bearing cup bottom portion 22b is 100%, the rigidity in the opening direction of each tip portion 12a is set to a low rigidity of about 13% of the rigidity of the bottom portion 22b.

The optimum value of the rigidity of the input shaft yoke tip portion 12a in the opening direction is 4 to 3 in relation to the change in the rotational balance of the propeller shaft as shown in FIG.
It is preferably set to 1 kN / mm.

More specifically, the rotational balance of the propeller shaft, as shown by the X-ray in FIG. 4, is due to the wear of the bottom surface of the bearing cup bottom portion 22b due to the frictional resistance with the tip portion 15b of the cross shaft 15 described above. The amount of backlash changes over time, and the amount of change in balance tends to increase as the backlash increases. Further, this rotation balance is as shown in the Y line of FIG.
It is also affected by the opening rigidity (elastic deformation) of the two tip portions 12a of No. 2, and the amount of change tends to increase abruptly as the value of opening rigidity decreases, and decreases as the value of opening rigidity increases.

Therefore, first, an allowable balance change amount of the propeller shaft (broken line in FIG. 4) is obtained in advance, and the rotational balance change amount (X
Line) and the area in which the amount of change in the rotational balance due to the both end portions 12a overlaps, the optimum input shaft yoke 12 is obtained.
The opening stiffness value of is calculated and this optimum value is 4 to 31 kN /
mm. Therefore, it is preferable to set the opening rigidity value of both tip portions 12a within this optimum value range.

When the above-mentioned components are assembled,
A small initial load in the axial direction is applied between the tip surface of the projection 21 of the tip portion 15b of the cross shaft 15 and the tip surface of the convex portion 27 of the bottom portion 22b of the bearing cup 22 with which the tip surface abuts. .

For the sake of convenience, the operation of this embodiment will be described below only on the input side. With the rotation of the drive shaft, the input load acts on the bearing cup 22 from the input shaft yoke 12 through both the tip portions 12a. However, at this time, the opening rigidity value of the both end portions 12a is about 4 which is the optimum value range.
Since it is set to ˜31 kN / mm, a spring action acts on both of the tip portions 12a. Therefore, abrupt torque transmission from the input shaft yoke 12 to the bearing cup 22 and the cross shaft 15 is suppressed, and the bearing cup bottom portion 22.
The abrupt abutment of the tip surface of the convex portion 27 of b with the tip surface of the cross shaft tip portion 15b in the axial direction is buffered, thereby suppressing the occurrence of backlash.

As a result, it is possible to prevent the propeller shaft from losing its balance in rotation, so that stable rotation can be obtained for a long period of time.

Further, since a spring action is exerted on both tip portions 12a, severe sliding friction between the tip surface of the convex portion 27 of the bearing cup bottom portion 22b and the tip surface of the protrusion 21 of the cross shaft tip portion 15b is prevented. Therefore, the occurrence of wear between the two 27 and 21 is suppressed, and the occurrence of rattling over time can be prevented.

Moreover, in this embodiment, the bearing cup 22 is supported by the abutment of the protrusion 27 of the bottom 22b and the protrusion 21 of the tip 15b with respect to the tip 15b. The contact area between the portion 27 and the protrusion 21 is significantly reduced as compared with the case where the entire tip surface of the tip portion 15b contacts the entire bottom surface. Therefore, in combination with the optimization of the opening rigidity of both the tip portions 12a as described above, it is possible to further suppress the occurrence of wear between the both ends 21 and 27.

Further, since the input shaft yoke 12 and the output shaft yoke 14 are molded by press molding, the molding work is facilitated and the yoke 12 can be made thinner overall, so that the radius R of the base of each tip 12a is reduced. It can be made smaller and the arm length of each tip 12a can be made longer,
This can further reduce the rigidity.

Since the tip portion 12a (holding hole 18) is arranged on the base end portion 22a side of the bearing cup 22 and not on the bottom portion 22b side, the bottom portion 22b is radially moved by the input load. Is reliably prevented from being compressed and deformed. Therefore, most of the input load does not act intensively on the side of the tip portion 23a of the needle roller 23, but inside thereof, that is, the inner end portion 23b opposite to the tip portion.
It can act on the side and be dispersed in the entire axial direction, and the friction between the inner peripheral surface of the bottom portion 22b, each cross roller needle roller 23, and the tip portion 15b of the cross shaft 15 can be made sufficiently small.

On the output shaft 13 side, the rotational torque is transmitted from the tip portion 15b of the cross shaft 15 to the tip portion 14a of the output shaft yoke 14 via the needle bearings 17. In this case as well, the input shaft 11 is used. By the same action as the side, the concentrated load is effectively prevented from being generated on the tip end side of each needle roller of the needle bearing 17, and the durability of the needle bearing 17 can be improved.

Further, since the widths of the respective tip portions 12a, 14a of the input shaft yoke 12 and the output shaft yoke 14 are formed to be sufficiently thinner than the axial length of the bearing cup 22, the bearing The holding position with respect to the cup 22 can be easily determined.

In the above-described embodiment, the description has been given centering on the input shaft yoke 12 side, but since the output shaft yoke 14 side is also the same as the input shaft yoke 12 side, the same operational effect can be obtained.

The present invention is not limited to the configuration of each of the above-described embodiments, and each configuration can be freely changed according to the spirit of the invention. For example, the input shaft yoke 12
It is possible to freely set the opening rigidity value of each tip portion within the range of 4 to 31 kN / mm depending on the size and specifications of the output shaft yoke 14.

The present invention can be applied not only to a power transmission mechanism such as a propeller shaft but also to a universal joint such as a steering mechanism.

[0045]

As is apparent from the above description, claim 1
According to the invention described in (1), the opening rigidity of both end portions of the yoke is set to be small and a spring action (elastic deformation) is exerted, thereby preventing occurrence of looseness between the bottom portion of the bearing cup and the tip portion of the cross shaft. Therefore, it is possible to prevent the occurrence of the rotational imbalance during the transmission of the rotational torque.

In particular, due to the spring action of both the tip portions,
It is possible to suppress the occurrence of wear over time between the bottom portion of the bearing cup and the tip portion of the cross shaft, and thereby to prevent backlash due to wear between the two.

According to the second aspect of the present invention, the effect of the first aspect of the invention can be obtained more reliably by obtaining the optimum opening rigidity value of the yoke tip portion.

According to the third aspect of the present invention, by forming the yoke by press molding, it is possible to increase the length of the arm at each tip portion, and further reduce the rigidity.

[Brief description of drawings]

FIG. 1 is a sectional view of essential parts showing an embodiment of a universal joint according to the present invention.

FIG. 2 is a side view showing a partial cross section of a universal joint in the present embodiment.

FIG. 3 is a graph showing the difference between the rigidity of the bearing cup in each embodiment and the opening rigidity of the conventional input shaft yoke tip and the input shaft yoke tip.

FIG. 4 is a graph for obtaining an optimum value of opening rigidity of a yoke tip portion in the present embodiment.

FIG. 5 is a sectional view of a main part of a conventional universal joint.

[Explanation of symbols]

11 ... Input shaft 12 ... Input shaft yoke 12a ... Tip 13 ... Output shaft 14 ... Output shaft yoke 15 ... Cross axis 15a ... intersection 15b ... Tip 16, 17 ... Needle bearing 18, 19 ... Holding hole 21 ... Protrusion 22 ... Bearing cup 22b ... bottom 23 ... Needle roller 27 ... Projection

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masanori Oonuma             1370 Onna, Atsugi, Kanagawa             Nissia Jex (72) Inventor Takayuki Yokota             1370 Onna, Atsugi, Kanagawa             Nissia Jex

Claims (3)

[Claims] 1. An input shaft yoke and an output shaft yoke respectively provided at opposite end portions of the input shaft and the output shaft, a cross shaft connecting the input shaft yoke and the output shaft yoke, and a bifurcation of each yoke. Needle bearings each having a bottomed bearing cup held in a holding hole formed in each of the tip ends of the cross-section, and each tip end of the cross shaft is inserted through the inside of the bearing cup. A universal joint in which the cross shafts are rotatably connected to each other, the rigidity in the opening direction of each yoke tip is set smaller than the rigidity of the bottom of the bearing cup, An initial load in the axial direction of the cross shaft tip portion is applied between the tip surface of the cross shaft tip portion and the bottom surface of the bottom of the bearing cup with which the tip surface abuts. Universal joint. 2. The opening rigidity of the tip of the yoke is 4 to 3
The universal joint according to claim 1, wherein the universal joint is set to 1 KN / mm. 3. The universal joint according to claim 1, wherein the yoke is formed by press molding.