JP2000120717A - Universal joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the life of a coupling type bearing in a universal joint by obtaining an appropriate seal with the use of a seal ring. SOLUTION: A packing 75b constituting a seal ring 75 is made of synthetic resin or the like, and is composed of an inner peripheral part 91 held between a core 75a and the outer periphery of a shank part 61, a dust lip 92 making contact with the outer periphery of an opening 71a of a bearing cup 71, and a grease lip 93 making contact with one end of the opening 71a. The inner diameter of the inner peripheral part 91 is less than the outer diameter of the shank part 61 so as to obtain an interference due to the difference between these diameters. Due to the interference, the inner peripheral part 91 is made into close contact with the shank part 61. In this phase, the interference between the inner peripheral part 91 and the shank part 61 is suitably adjusted so that the insertion load of the seal ring 75 is set to be in a range from 15 to 50 N, and accordingly, the seal ring 75 can be precisely positioned with respect to the shank part 61, and then be fixed. Thus, it is possible to prevent the dust lip 92 and the grease lip 90 from being applied with an excessive load, thereby it is possible to prevent early abrasion and sealing ability of the seal ring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a universal joint used as an automobile steering joint or the like.

[0002]

2. Description of the Related Art Japanese Utility Model Publication No. 7-25459 discloses a universal joint used for a steering shaft or the like. In this universal joint, there is disclosed a universal joint in which a spider connecting a pair of yokes constituting the yoke is supported using a cup-shaped bearing in a bearing hole formed at a tip of a pair of arms constituting each yoke. ing. In this universal joint, the seal ring is fixed to the shaft of the spider, the lip of the seal ring is brought into contact with the cup end of the bearing, and the lip slides on the surface of the cup end to infiltrate muddy water into the lip, that is, into the bearing. Has been prevented. In this type of seal ring, to fix the seal ring to the spider shaft,
An interference is provided between the seal ring and the spider shaft. That is, the rubber disposed between the inner diameter side of the core metal of the seal ring and the outer peripheral side of the spider shaft portion is compressed and deformed, so that the seal ring is fastened and fixed to the spider shaft portion.

[0003]

However, in the above universal joint, if the compressive force of the seal ring is not appropriate, the following inconvenience occurs.

[0004] For example, when the compressive force of the seal ring is small (that is, when the interference is small), slippage occurs between the seal ring and the spider shaft, and the seal ring rotates on the spider shaft. As a result, muddy water from the outside enters the inside of the bearing via the spider shoulder and the periphery of the spider shaft, greatly reducing the life of the bearing.

On the other hand, when the compression force of the seal ring is large (that is, when the interference is large), when the seal ring is inserted into the spider shaft portion, the seal ring is inserted until the core metal of the seal ring contacts the spider shoulder. Since the rubber between the core bar and the spider shaft portion is in contact with the spider shaft in a deformed state in the spider axial direction, when the insertion force is removed from the seal ring, a gap is generated between the core bar and the spider shoulder. For this reason, the interference of the lip provided on the seal ring in the spider axial direction becomes excessive, leading to early abrasion and deterioration of the sealability.

Accordingly, an object of the present invention is to increase the life of a cup-shaped bearing of a universal joint and, consequently, the life of the universal joint itself by appropriately setting a seal by a seal ring.

[0007]

In order to solve the above-mentioned problems, a universal joint according to the present invention comprises a pair of shafts at both ends of a cross shaft formed by a pair of cup-shaped bearings respectively fitted into bearing holes of opposed arms. A universal joint having a pair of seal rings for supporting a radial portion rotatably around an axial direction and sealing a gap between an opening side of the pair of bearings and a root side of the pair of shaft radial portions. Wherein the seal ring comprises an annular core, and a packing made of any of synthetic rubber and synthetic resin and compressed and deformed by being sandwiched between the core and the shaft diameter portion. An insertion load when the ring is mounted on the shaft diameter portion is 15 N or more and 50 N or less, and an outer diameter of the shaft diameter portion is 9.5 mm or more and 10.5 or more.
mm or less.

As described above, in the universal joint according to the present invention, the seal ring is made of an annular core metal, one of synthetic rubber and synthetic resin, and is sandwiched between the core metal and the shaft diameter portion. And a packing which is compressed and deformed, and an insertion load when the seal ring is mounted on the shaft diameter portion is 1
5N or more and 50N or less, and the outer diameter of the shaft diameter portion is 9.
Since it is 5 mm or more and 10.5 mm or less, the seal ring can be fixed at an appropriate position of the shaft diameter portion with an appropriate strength, and the fixed seal ring is brought into close contact with the opening side of the bearing in an appropriate state, so that the inside of the bearing can be fixed. It can be kept airtight. Therefore, the life of the bearing can be maintained and the life of the universal joint itself can be increased by appropriately setting the seal of the bearing.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] FIG. 1 is a partial sectional view illustrating the structure of a universal joint according to a first embodiment.
The illustrated universal joint is for connecting a steering shaft constituting a steering device of a vehicle, and has a structure in which a pair of yokes 2 and 4 are connected. The shaft 1 extending from the yoke 2 is connected to the handle, and the shaft 5 extending from the yoke 4 is connected to the wheel.

One yoke 2 is connected to the other yoke 4 via a spider 6. One yoke 2
It is of a bolted type, and has a structure in which a base 21 fitted to the shaft 1 and a forked portion 22 for connecting to the spider 6 are integrally manufactured by press molding of a sheet metal. The other yoke 4 is of a welding and fixed type, and has a structure in which a base 41 fitted to the shaft 5 and a forked portion 42 for connecting to the spider 6 are integrally manufactured.

The fork portion 22 has a pair of arms 22 extending substantially parallel to the shaft axis direction from a position facing the base portion 21.
a and 22b. A bearing hole 22c for holding the cup-shaped bearing 7 is formed through the arm 22a, 22b at a position facing the tip of the arm 22a, 22b. A U-shaped groove 21c having a substantially U-shaped cross section corresponding to the shape of the shaft 1 is formed in the base 21 by a pair of fastening portions 21a and 21b. A nut hole 21d is formed in one of the fastening portions 21a, and the nut 11 is press-fitted and fixed in the nut hole 21d. A bolt hole 21e is formed in the other fastening portion 21b, and a bolt (not shown) is inserted into the bolt hole 21e and fastened to the nut 11.

The fork portion 42 also includes a pair of arms 42 extending substantially parallel to the shaft axis direction from a position facing the base portion 41.
a, 42b. A bearing hole 42c for holding the cup-shaped bearing 107 is formed through the arm 42a, 42b at a position facing the distal end of the arm 42a, 42b. A through hole 41c extending in the axial direction is formed in the base 41, and the shaft 5 is fitted into the through hole 41c and fixed by welding.

FIG. 2 is a view for explaining the structure of the spider 6, and shows a cross section taken along the line AA of FIG. The spider 6 includes cylindrical shaft diameter portions 61, 61, 62, 62 extending in four directions around a main body 60. The pair of opposed shaft diameter portions 61, 61 are inserted into bearing holes 22c of the arms 22a, 22b in FIG. 1, and are supported by the bearing 7 so as to be rotatable around their axial directions. Also, a pair of opposed shaft diameter portions 6
2, 62 are bearing holes 42 of the arms 42a, 42b of FIG.
c and is rotatably supported by the bearing 107 around its axial direction. Note that the shaft diameter portions 61, 61, 62,
The end faces of 62 are each provided with a bottomed axial hole 65 that opens at these end faces.

Returning to FIG. 1, the bearing hole 22 of the arm 22a is
c is a needle 73 around the shaft diameter portion 61 of the spider 6.
Is sealed by the bearing cup 71 in a state where is disposed. The bearing cup 71 is press-fitted into the bearing hole 22c, and is fixed to the arm 22a by caulking at an outer edge portion thereof. The inner end of the bearing cup 71 is in close contact with the seal ring 75. The seal ring 75 includes an annular core bar 75 a and a flexible packing 75 b wrapping the core bar 75 a, and is sandwiched between the main body 60, which is the root side of the shaft diameter portion 61, and the opening of the bearing cup 71. To seal the bearing 7.

An axial hole 6 formed in the end face of the shaft diameter portion 61
In 5, a thrust piece 8 made of a synthetic resin is fitted. When the thrust piece 8 is inserted into the axial hole 65, the end of the thrust piece 8 projects from the end surface of the shaft diameter portion 61 and engages with the bottom surface of the bearing cup 71. When press-fitting the bearing cup 71, the thrust piece 8
Of the spider 6, a preload toward the center in the axial direction is applied to the shaft diameter portions 61, 61 at both ends of the spider 6, and the spider 6 sandwiched between the arms 22a, 22b.
Is held at a predetermined position in the axial direction.

Although detailed description is omitted, the arm 2
The bearing 7b of the arm 22a has the same structure as the bearing 7 of the arm 22a and is sealed by a seal ring 75. The bearing 107 of the arms 42a and 42b has the same structure as the bearing 7 of the arm 22a, and is not shown. It is sealed by a seal ring similar to the illustrated seal ring 75.

FIG. 3 is a partially enlarged sectional view for explaining the structure of the seal ring 75. As shown in FIG. The core metal 75a constituting the seal ring 75 is a ring-shaped metal member having a substantially L-shaped cross section. Packing 75b constituting seal ring 75
Is made of synthetic rubber or synthetic resin, and comes into contact with the inner peripheral portion 91 sandwiched between the core metal 75a and the outer periphery of the shaft diameter portion 61, and the outer periphery of the distal end side of the opening 71a of the bearing cup 71, thereby invading foreign matter. And a grease slip 93 that abuts on the tip of the opening 71a of the bearing cup 71 to prevent leakage of the lubricant. The inner diameter of the inner peripheral portion 91 is smaller than the root outer diameter of the shaft diameter portion 61, and the inner peripheral portion 91 is compressed and deformed in a direction perpendicular to the axial direction of the shaft diameter portion 61 by the interference of the difference. Adheres to the shaft diameter portion 61. As a result, the seal ring 75 is fixed to the shaft diameter portion 61, and the airtightness between the shaft diameter portion 61 and the seal ring 75 is maintained. Also, by properly adjusting the interference between the inner peripheral portion 91 and the shaft diameter portion 61 so that the insertion load of the seal ring 75 becomes 15 N to 50 N, the seal ring 75 is moved to the shaft diameter portion 61.
When fitted, the lower surface of the core bar 75a is brought into contact with the shoulder 60a provided on the spider body 60 so that no gap is formed. Specifically, the outer diameter of the shaft diameter portion 61 is 9.5 mm.
１10.5 mm and the insertion load of the seal ring 75 is 1
The interference between the inner peripheral portion 91 and the shaft diameter portion 61 was adjusted so as to be 5N to 50N. Thereby, the seal ring 75
Can be accurately positioned and fixed with respect to the shaft diameter portion 61, and it is possible to prevent an excessive load from being applied to the dust lip 92 and the grease slip 93, thereby preventing early wear and deterioration in sealing performance.

Hereinafter, specific embodiments will be described.
The material of the packing 75b is synthetic rubber, and its hardness is
HS was about 70. The outer diameter of the shaft diameter portion 61 of the spider 6 was 10 mm. Further, by adjusting the thickness T of the inner peripheral portion 91 of the seal ring 75, or adjusting the axial length L of the core bar 75a, the insertion load of the seal ring 75 is reduced by one.
It adjusted so that it might be in the range of 5N-50N. At this time, the inner circumference of the packing 75b of the seal ring 75 and the spider 6
Grease was applied to the contact surface of the shaft diameter portion 61 with the outer periphery.
The outer diameter of the bearing 7, that is, the bearing cup 71 is 16 mm.
And

FIG. 4 shows the insertion load of the seal ring 75,
6 is a graph for explaining a relationship between a shaft 61 and a slip torque between inner peripheral portions of a seal ring 75. In the graph, the band-shaped portion indicated by oblique lines is within a range of test values obtained as a result of performing an experiment of measuring a sliding torque of the seal ring 75 by changing an insertion load into the shaft diameter portion 61 of the seal ring 75. is there.
When the insertion load of the seal ring 75 is 15N to 50N,
The sliding torque of the seal ring 75 is 48 to 230 mN
It can be seen that m is obtained.

In this embodiment, the maximum slip torque between the dust lip 92 and the grease slip 93 and the bearing cup 71 is about 45 mN · m. This value is determined by the slip torque between the seal ring 75 and the shaft diameter portion 61 (48 to 230).
mN · m), it is possible to prevent the seal ring 75 from slipping on the shaft diameter portion 61, and it is understood that the seal ring 75 is securely fixed to the shaft diameter portion 61.

According to many experimental results, when the insertion load when inserting the seal ring 75 into the shaft diameter portion 61 exceeds 50 N, the seal ring 75 is excessively fastened to the shaft diameter portion 61 and the shaft diameter portion 61 Insert the seal ring 75 into the core 7
Even if 5a is pressed against shoulder 60a, if the load on seal ring 75 is removed, a gap may be formed between core metal 75a and shoulder 60a due to the elasticity of packing 75b. That is, since the inner peripheral portion 91 sandwiched between the core metal 75a and the shaft diameter portion 61 is inserted in a state of being deformed in the axial direction, after removing the insertion load, the seal ring 75 is deformed by an amount corresponding to the deformation. Is returned to the tip end side of the shaft diameter portion 61, and a gap is generated between the core metal 75a and the shoulder portion 60a (see FIG. 5). Moreover, in the seal ring 75 fixed in this manner, the axial interference of the grease slip 93 becomes excessively large, so that an excessive load is applied to the grease slip 93 and the grease slip 93 is worn out at an early stage, and the sealing performance is deteriorated. In some cases, water may enter the bearing, leading to a shortened life.

[Second Embodiment] FIGS. 6 and 7 are partial cross-sectional views illustrating the structure of a universal joint according to a second embodiment.
The universal joint according to the second embodiment is a modified example of the universal joint according to the first embodiment, and the same portions are denoted by the same reference numerals and overlapping description will be omitted.

The universal joint of the second embodiment is a spider 2
06 has a shape different from that of the first embodiment, and accordingly, the shape of the seal ring 275 also differs from that of the first embodiment. Specifically, the shoulder 260 a of the spider 206 is a part of a conical shape, and the radius decreases toward the tip of the shaft diameter portion 261. The seal ring 275 includes a metal core 75a having a substantially L-shaped cross section and a packing 275b, and the latter packing 275b has a spider 206 in addition to the inner peripheral portion 291, the dust lip 92, and the grease slip 93. A lower end 295 having a shape corresponding to the shoulder 260a and abutting on the shoulder 260a after assembly is provided.

As described above, the present invention has been limited in accordance with the embodiment. However, the present invention is not limited to the above embodiment. For example, in the above embodiment, the core metal 75a has an L-shaped cross section, but may have a substantially U-shaped cross section, or may have a simple rectangular shape. In addition, Spider 20
The shoulder 260a of No. 6 can be a curved surface. In this case, the shape of the lower end 295 is changed according to the shape of the shoulder 260a. The packing 27 of the seal ring 275
5b need not include both dust lip 92 and grease slip 93, and may be a single lip.

[0025]

As is clear from the above description, according to the universal joint of the present invention, the insertion load when the seal ring is mounted on the shaft diameter portion is 15 N or more and 50 N or less. The outer diameter of the part is 9.5 mm or more and 10.5 mm
Since it is below, the seal ring can be fixed at an appropriate position on the shaft diameter portion with appropriate strength, and the fixed seal ring can be tightly adhered to the opening side of the bearing in an appropriate state to keep the inside of the bearing airtight. It is possible to maintain the life of the bearing by appropriately setting the seal of the bearing, and to increase the life of the universal joint itself.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a universal joint according to a first embodiment of the present invention.

FIG. 2 is a perspective view of the spider AA constituting the universal joint of FIG. 1;
It is arrow sectional drawing.

FIG. 3 is an enlarged sectional view of a main part of a bearing incorporated in the universal joint of FIG. 1;

FIG. 4 is a diagram illustrating characteristics of the universal joint according to the first embodiment.

FIG. 5 is a comparative diagram for reference.

FIG. 6 is a partial sectional view of a universal joint according to a second embodiment.

FIG. 7 is an enlarged sectional view of a main part of a bearing incorporated in the universal joint of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shaft 2, 4 Yoke 5 Shaft 6 Spider 7 Bearing 21a, 21b Tightening part 22 Fork part 22a, 22b Arm 22c Bearing hole 42 Fork part 60 Main body 60a Shoulder part 61, 62 Shaft diameter part 71 Bearing cup 71a Opening 73 Needle 75 seal ring 75a mandrel 75b packing 91 inner peripheral part 92 dust lip 93 grease slip

Claims (1)

[Claims] 1. A pair of cup-shaped bearings fitted into bearing holes of opposing arms respectively support a pair of shaft diameter portions at both ends of a cross shaft so as to be rotatable around an axial direction. A universal joint including a pair of seal rings for sealing between an opening side of a bearing and a root side of the pair of shaft diameter portions, wherein each of the pair of seal rings has an annular core metal,
A packing made of any one of synthetic rubber and synthetic resin and being compressed and deformed by being sandwiched between the cored bar and the shaft diameter portion; each of the pair of seal rings is mounted on the shaft diameter portion; A universal joint, wherein an insertion load at that time is 15 N or more and 50 N or less, and an outer diameter of each of the pair of shaft diameter portions is 9.5 mm or more and 10.5 mm or less.