JP2004211782A - Universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase permissible torque without enlarging boundary dimensions of an universal joint. <P>SOLUTION: The universal joint is provided with steps of: combining to be engaged with each other at a central axis Az direction; crossing a primary trunnion shaft 2 and a secondary trunnion shaft 5 at right angle by means of a pair of intermediate rings 6 which are fastened each other with bolts 7 or the like; and rotatably retaining the trunnion shafts 2 and 5 around a center line for both shafts on conditions that both trunnion shafts 2 and 5 are offset to the central axis Az direction orthogonal to both trunnion shafts 2 and 5. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a universal joint.
[0002]
[Prior art]
The universal joint has a basic configuration in which one shaft and the other shaft of a cross shaft are connected to a drive shaft and a driven shaft, respectively, to transmit a driving force. Here, roller bearings are mounted on both ends of each of the cross shafts in order to allow each of the cross shafts to relatively rotate around the shaft. The outer ring of the roller bearing is sandwiched between a yoke and a cap which are fastened to each other with bolts and nuts from both sides, and this yoke is connected to a drive shaft or a driven shaft (for example, see Patent Document 1). In addition, serrations or keys are provided on the connection surface between the yoke and the cap, so that they can withstand a force applied in a direction parallel to the connection surface by torque.
[0003]
[Patent Document 1]
Japanese Patent No. 2987803 (pages 1 to 3, FIGS. 3 to 5)
[0004]
[Problems to be solved by the invention]
In the conventional universal joint as described above, in the torque transmission between the drive shaft and one of the cross shafts and between the other of the cross shaft and the driven shaft, bending stress or tensile stress acts on the bolt. I do. Also, the serrations and keys are given power. In such a configuration, when it is desired to increase the allowable torque, it is necessary to increase the size of the serration and the key while increasing the thickness of the bolt. However, doing so increases the external dimensions of the entire universal joint, which is contrary to the demand for compactness. That is, it is difficult to increase the allowable torque while maintaining the external dimensions.
[0005]
In view of the above conventional problems, an object of the present invention is to increase the allowable torque without increasing the external dimensions of the universal joint.
[0006]
[Means for Solving the Problems]
A universal joint according to the present invention has a first trunnion shaft, a first trunnion member for mounting to a drive shaft, and a second trunnion shaft disposed opposite to the first trunnion member; A second trunnion member for attaching the first trunnion shaft and the second trunnion shaft to each other so as to be rotatable around a center line thereof while the first trunnion shaft and the second trunnion shaft are perpendicular to each other. A plurality of intermediate wheels that are engaged with each other so as to mesh with each other in a central axis direction, and a fastening member that fastens the plurality of intermediate wheels in the central axis direction.
In the universal joint configured as described above, the plurality of intermediate wheels are coupled so as to mesh with each other in the central axis direction, so that torque is transmitted via the coupled body of the intermediate wheels, and hardly reaches the fastening member. Therefore, the fastening member can be made thinner, and accordingly, each trunnion shaft can be made thicker.
[0007]
Further, in the universal joint (Claim 1), the first trunnion shaft and the second trunnion shaft may be at positions offset from each other in the direction of the central axis (Claim 2).
In this case, each trunnion shaft can secure a shaft diameter of a desired thickness without being mutually limited. Therefore, it is possible to contribute to an increase in allowable torque. Also, the offset disperses the stress generated in the combined body of the intermediate wheels during torque transmission. Therefore, it is possible to prevent the allowable torque from being reduced due to the stress concentration and to contribute to the increase in the allowable torque.
[0008]
In the universal joint (Claim 2), the intermediate wheel may have a meshing surface parallel to the center axis direction (Claim 3).
In this case, the meshing surface parallel to the central axis direction serves as a pressure receiving surface for torque, and substantially no torque is applied to the fastening member. Therefore, the fastening member can be made as thin as possible, and accordingly, each trunnion shaft can be made thicker. Further, the length of the meshing surface can be sufficiently secured according to the offset amount. Therefore, a sufficient pressure receiving area for the torque can be secured.
[0009]
In the above universal joint (Claim 2), there is a pair of intermediate wheels, each of which has four half retaining surfaces for retaining outer rings rotatably mounted on both ends of each trunnion shaft. (Claim 4).
In this case, by fastening the pair of intermediate wheels to each other with the fastening member, the outer ring sandwiched between the half holding surfaces can be tightened. Therefore, creep of the outer race is prevented.
[00010]
Further, in the universal joint (claim 4), bearings may be attached to both ends of each trunnion shaft, and an outer ring of the bearing may be held by a holding surface (claim 5).
In this case, it is easy to replace the finished bearing unit.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is an exploded perspective view of a universal joint according to an embodiment of the present invention, and FIG. 2 is a perspective view of a state where the universal joint is assembled. In FIG. 1, X, Y, and Z are three directions orthogonal to each other. The right end first trunnion member 1 has a shaft holding portion 1a having a through hole 1h in the Y direction, and a flange portion 1b formed integrally with the shaft holding portion 1a. The flange portion 1b is connected to a drive shaft (not shown). As shown in the figure, the upper and lower surfaces and the end surface in the -Z direction of the shaft holding portion 1a are flat, and on both sides, the flange portion 1b side is a cylindrical surface, and a tapered surface is tapered toward the end surface. The first trunnion shaft 2 having the center line Ay in the Y direction is fitted (shrink-fitted) into the through hole 1h, and the inner ring 31, the roller 32, and the outer ring 33 are assembled at both ends 2a protruding from the through hole 1h. A roller bearing 3 is mounted as a product.
[0012]
On the other hand, the second trunnion member 4 at the left end disposed opposite to the first trunnion member 1 is also substantially the same as the first trunnion member 1 having the shaft holding portion 4a and the flange portion 4b. A second trunnion shaft 5, which is substantially the same member as the first trunnion shaft 2, is fitted into the through hole 4h of the portion 4a. Further, roller bearings 3 are mounted on both ends of the second trunnion shaft 5. However, as shown, the second trunnion shaft 5 is disposed so that the center line Ax is in the X direction and is orthogonal to the first trunnion shaft 2, and the flange portion 4b of the second trunnion member 4 is not shown. Connected to drive shaft.
[0013]
Next, the pair of intermediate wheels 6, which are substantially the same member, is basically in the form of a ring or a tube, and has a predetermined unevenness formed on the end face in the center axis Az direction parallel to the Z direction. I have. Specifically, the outer end surface 6a (on the side of each trunnion member 1, 4) has a shape having a step at about 90 degrees in the circumferential direction, and eight end portions 6 for penetrating the bolt 7 in parallel with the central axis Az direction. Hole 6h is formed. The inner ring (the sides facing each other) has an outer ring concaved in a semicircular shape (that is, half of a circular hole) for holding the second trunnion shaft 5 between the pair of end surfaces 6b in a range of 90 degrees in the circumferential direction. An outer ring holding concaved in a semicircular shape for holding the first trunnion shaft 2 between a portion having the holding surface 6c and a pair of end surfaces 6d similarly offset in the Z direction from the end surface 6b within a range of 90 degrees. The portion provided with the surface 6e has a shape alternately arranged in the circumferential direction. The two pairs of outer ring holding surfaces 6c and 6e that face each other in the radial direction are out of phase with each other by 90 degrees. A meshing surface 6f parallel to the central axis Az direction is formed between the end surfaces 6b and 6d adjacent to each other in the circumferential direction. Note that the engagement surface 6f includes a central axis Az on an extension surface thereof.
[0014]
The length of the meshing surface 6f in the direction of the central axis Az corresponds to the amount of the offset (hereinafter, referred to as an offset amount). Further, the offset amount has a predetermined value such that the end surfaces of the shaft holding portions 1a and 4a of the trunnion members 1 and 4 do not interfere with each other when the universal joint is assembled. On the other hand, the inner peripheral surface of the intermediate wheel 6 has such an extent that the shaft holding portions 1a and 4a can be fitted and swinged around the center lines Ax and Ay of the through holes 1h and 4h. It has a shape with sufficient inner dimensions.
The pair of intermediate wheels 6 are arranged so as to face each other with a phase shift of 90 degrees in the circumferential direction. Hereinafter, for convenience, the intermediate wheel 6 on the first trunnion member 1 side is referred to as a first intermediate wheel, and the intermediate wheel 6 on the second trunnion member 4 side is referred to as a second intermediate wheel.
[0015]
In order to assemble the universal joint configured as described above into the state shown in FIG. 2, the shaft holding portion 1a of the first trunnion member 1 is inserted through the first intermediate wheel 6, and the first trunnion shaft is inserted into the shaft holding portion 1a. 2 and the roller bearings 3 are mounted on both ends thereof. Similarly, the shaft holding portion 4a of the second trunnion member 4 is inserted through the second intermediate wheel 6, the second trunnion shaft 5 is fitted into the shaft holding portion 4a, and the roller bearings 3 are mounted on both ends thereof. Then, the first intermediate wheel 6 and the second intermediate wheel 6 are coupled so as to be intimately engaged with each other, and are fastened using fastening members such as bolts 7 and nuts 8.
[0016]
The pair of intermediate wheels 6 fastened to each other in this manner causes the first trunnion shaft 2 and the second trunnion shaft 5 to be orthogonal to each other and to be offset in the direction of the central axis Az orthogonal to both the trunnion shafts 2 and 5. And hold it. Further, the outer ring 33 of the roller bearing 3 is sandwiched between a pair of outer ring holding surfaces 6c or 6e facing each other in the Z direction, and is tightened by fastening. Thus, each of the trunnion shafts 2 and 5 is held rotatably around the center line Ax and Ay of each of the trunnion shafts 2 and 5 with respect to the pair of intermediate wheels 6. Since the predetermined offset amount is ensured as described above, the end surfaces of the shaft holding portions 2 and 5 of the trunnion members 1 and 4 do not interfere with each other.
[0017]
In the universal joint thus assembled, for example, when a torque is applied to the first trunnion member 1 from the drive shaft, the torque is transmitted from the first trunnion shaft to the combined body of the intermediate wheel 6 via the roller bearing 3. The power is further transmitted to the second trunnion shaft 5 via the roller bearing 3 on the second trunnion shaft 5 side, and transmitted from the second trunnion member 4 to the driven shaft. Here, since the trunnion shafts 2 and 5 are held in a state where they are offset from each other by a predetermined amount in the direction of the center axis Az, the trunnion shafts 2 and 5 are shafts having a desired thickness without being mutually limited. The diameter can be secured. Therefore, it is possible to contribute to an increase in allowable torque. Further, the stress generated in the combined body of the intermediate wheels 6 during torque transmission is dispersed by the offset. Therefore, it is possible to prevent the allowable torque from being reduced due to the stress concentration and to contribute to the increase in the allowable torque.
[0018]
Further, although torque transmission is also performed between the pair of intermediate wheels 6, since the pair of intermediate wheels 6 are connected so as to mesh with each other in the direction of the central axis Az, bending / tensile stress is applied to the bolt 7 for fastening the two. Has little effect. In particular, the meshing surface 6f is parallel to the direction of the central axis Az, and here receives the entire torque vertically. Therefore, as long as the bolt 7 is not deformed, the bolt 7 does not exert a force component. That is, bending / tensile stress does not substantially act on the bolt 7. The meshing surface 6f has an area obtained by multiplying the length of the meshing surface 6f by the thickness of the intermediate wheel 6 with the offset amount as the length of the meshing surface 6f. Therefore, a sufficiently large pressure receiving area can be secured according to the offset amount, and the surface pressure can be kept small. As a result, the allowable torque can be increased without increasing the external dimensions of the entire universal joint. Further, regardless of the circumferential direction of torque transmission, the engagement surface 6f serving as the pressure receiving surface is always at a position 180 degrees out of phase. Therefore, force is applied to the entire intermediate wheel 6 in a well-balanced manner. Therefore, it can withstand high torque.
[0019]
As described above, since the bending / tensile stress hardly acts on the bolt 7, the bolt 7 can be used as thin as possible. Therefore, the outer diameter of each of the trunnion shafts 2 and 5 can be increased to increase the rigidity and the allowable torque to be increased by the amount by which the bolt 7 can be made thinner.
In addition, as compared with the case where only the roller 32 and the outer ring 33 are attached to both ends of the trunnion shafts 2 and 5 (without the inner ring), the roller bearing 3 as a finished product including the inner ring 31 as described above is used, so Replacement of three bearings is easy and convenient.
Further, the outer ring 33 of the roller bearing 3 is held between the pair of outer ring holding surfaces 6c and 6e and is tightened by fastening, so that no creep occurs between the outer ring 33 and the intermediate wheel 6. Therefore, seizure of the outer ring 33 and wear of the outer ring holding surfaces 6c and 6e can be prevented.
[0020]
In the above embodiment, the trunnion shafts 2 and 5 are described as being fitted into the shaft holding portions 1a and 4a. However, the trunnion shafts 2 and 5 may be integrated with the shaft holding portions 1a and 4a. FIG. 3 is a perspective view showing a configuration in which the first trunnion shaft 2 is formed integrally with the shaft holding portion 1a of the first trunnion member 1. In this case, the work of fitting the trunnion shaft 2 can be omitted, and the number of members is reduced, but the operation of passing the trunnion shaft 2 through the intermediate wheel 6 is somewhat troublesome. Further, in such a configuration, if the trunnion shafts 2 and 5 are brought into contact with each other, the offset amount can be made equal to the shaft diameter of the trunnion shaft 2. Also, the center line of the two trunnion shafts 2 and 5 can be made closer by setting the offset amount to the shaft diameter of the trunnion shaft 2 or less. It is necessary to provide the recesses 2b and 5b. When the recesses 2b and 5b are provided, the shaft diameter becomes smaller by that amount, so that the mechanical strength is slightly reduced.
[0021]
Further, in the above embodiment, the pair of intermediate wheels 6 are coupled so as to mesh with each other in the direction of the central axis Az, but the number and configuration of the intermediate wheels 6 are not limited thereto, and other intermediate wheel structures may be used. It is possible. For example, FIG. 4 is a plan view showing an example of another intermediate wheel structure. In this case, the three intermediate wheels 61, 62, 63 divided into three in the Z direction are engaged with serrations 61a, 62a, 63a formed on the boundary surface of each other, and fastened with bolts 7 or the like. In this case, strictly, torque causes a component of a force to separate the intermediate wheels 61 to 63 from each other along the grooves of the serrations 61a, 62a, 63a, and a bending / tensile stress acts on the bolt 7. The serrations 61a, 62a, and 63a can be provided in a very wide range of the end faces of the intermediate wheels 61 to 63. Therefore, the above components are reduced by frictional resistance, and the bending and tensile stress acting on the bolt 7 can be suppressed to a very small value. it can. Therefore, as in the case of the above-described embodiment, the rigidity can be increased and the allowable torque can be increased by making the bolt 7 thinner and making each of the trunnion shafts 2 and 5 correspondingly thicker.
[0022]
Further, if the middle intermediate wheel 62 in FIG. 4 is eliminated, and the first trunnion shaft 2 and the second trunnion shaft 5 are cut off at the intersection, for example, so as to be larger than each other, and intersect without offset. A compact configuration in the Z direction as shown in FIG.
[0023]
【The invention's effect】
The present invention configured as described above has the following effects.
According to the universal joint of the first aspect, the torque is transmitted through the coupling body of the intermediate wheel and hardly reaches the fastening member. Therefore, the fastening member can be made thinner, and each trunnion shaft is made thicker accordingly. As a result, the rigidity can be increased and the allowable torque can be increased. Thus, the rigidity can be increased without increasing the external dimensions, and the allowable torque can be increased.
[0024]
According to the universal joint of the second aspect, each trunnion shaft can secure a shaft diameter of a desired thickness without being mutually limited, and can contribute to an increase in allowable torque. Further, since the offset causes the stress generated in the combined body of the intermediate wheels at the time of torque transmission to be dispersed, it is possible to avoid reduction in allowable torque due to stress concentration and to contribute to increase in allowable torque.
[0025]
According to the universal joint of the third aspect, the engaging surface parallel to the central axis direction serves as a pressure receiving surface against the torque, and the torque is not substantially applied to the fastening member. Therefore, the fastening member can be thinned to the minimum. To that extent, each trunnion shaft can be made thicker to increase rigidity and increase allowable torque. Further, the length of the meshing surface can be sufficiently secured according to the offset amount. Therefore, a sufficient pressure receiving area for the torque can be secured, and the allowable torque can be increased.
[0026]
According to the universal joint of the fourth aspect, by fastening the pair of intermediate wheels to each other with the fastening member, the outer ring sandwiched between the half holding surfaces can be tightened, so that creep of the outer ring can be prevented. . Therefore, seizure of the outer ring and wear of the outer ring holding surface can be prevented.
[0027]
According to the universal joint of claim 5, it is easy to replace the finished bearing unit, which is convenient.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a universal joint according to an embodiment of the present invention.
FIG. 2 is an assembled view of the universal joint of FIG. 1;
FIG. 3 is an example in which the configuration of FIG. 1 is partially modified, and is a perspective view in which a trunnion shaft is integrally formed with a trunnion member.
FIG. 4 is a plan view showing a universal joint of another configuration having a different intermediate wheel structure.
FIG. 5 is a plan view showing yet another configuration of the universal joint having a different intermediate wheel structure.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 first trunnion member 2 first trunnion shaft 3 roller bearing 4 second trunnion member 5 second trunnion shaft 6 intermediate wheel 6c, 6e outer ring holding surface 6f meshing surface 7 bolt 8 nut

Claims (5)

A first trunnion member having a first trunnion shaft for mounting to a drive shaft;
A second trunnion member disposed opposite to the first trunnion member, having a second trunnion shaft, and attached to a driven shaft;
The first trunnion shaft and the second trunnion shaft are rotatably held around their center lines in a state where the first trunnion shaft and the second trunnion shaft are perpendicular to each other, and are coupled so as to mesh with each other in a center axis direction perpendicular to each trunnion shaft. Multiple intermediate wheels
A fastening member for fastening the plurality of intermediate wheels in the direction of the central axis. The universal joint according to claim 1, wherein the first trunnion shaft and the second trunnion shaft are at positions offset from each other in the direction of the central axis. The universal joint according to claim 2, wherein the intermediate wheel has a meshing surface parallel to the central axis direction. 3. The universal joint according to claim 2, wherein there are a pair of the intermediate wheels, each of which has four half retaining surfaces for retaining outer rings rotatably mounted on both ends of each of the trunnion shafts. 4. The universal joint according to claim 4, wherein bearings are mounted on both ends of each of the trunnion shafts, and outer rings of the bearings are held by the holding surfaces.

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