JP6645550B2 - Universal joint - Google Patents

Description

  The present invention relates to a universal joint having a pair of yokes, a cross shaft, and a needle bearing.

As an example of the universal joint, there is a universal joint having a structure including a pair of yokes, a cross shaft connecting these yokes, and a needle bearing. The yoke is formed in a U-shape by a pair of arms and a base connecting these arms. A shaft insertion hole through which the shaft of the cross shaft is inserted is formed in the arm.
The arms of the other yoke are arranged between the arms of one yoke such that the axes of the shaft insertion holes of the yokes are orthogonal to each other. The needle bearing has a plurality of needle rollers disposed outside the shaft portion, and an outer ring having an annular body disposed between the plurality of needle rollers and the shaft insertion hole. The four shaft portions of the cross shaft are rotatably supported by the needle bearings in the shaft insertion holes of both yokes.

As a needle bearing for such a universal joint, an inward flange portion (curl) is formed on one end in the axial direction (a base end side of the shaft portion) of an annular body forming an outer ring while bending toward the shaft portion. There is something. The inward flange portion is provided for the purpose of preventing foreign matters or mixing in the bearing, grease in the bearing from flowing out, and the needle from jumping out. In addition, a sealing device is attached to the base end of the shaft to seal the space between the inward flange and the shaft.
Conventional examples of a universal joint having a pair of yokes, a cross shaft, and a needle bearing include those described in Patent Documents 1 and 2.

Patent Literature 1 discloses that the outer surface of a bearing case has a convex spherical surface for the purpose of preventing an uneven load from occurring and preventing a reduction in service life by always keeping the orbit of the bearing case and the axis of the trunnion parallel. It describes that the inner surface of the bearing hole of the yoke has a concave spherical shape and the inner surface of the bearing hole of the yoke is spherically fitted.
Patent Literature 2 discloses that an end of a journal shaft portion and a seal ring are provided for the purpose of preventing an edge load from being generated on a needle roller and avoiding breakage of a seal ring and poor rolling of the needle roller. It is described that a step recess for accommodating the needle roller is provided around each of the journal shaft portions at an intermediate position between the two.

JP-A-2002-89584 JP-A-9-151958

The above-mentioned universal joint transmits torque from a steering column side to a steering gear mechanism, for example, to a steering apparatus of a vehicle equipped with a column assist type (a steering assist mechanism is provided on a steering column side) electric power steering apparatus. Used as a universal joint for the steering shaft. In this application, a high load acts on the needle bearing constituting the universal joint, and the needle rollers repeatedly and strongly collide with the inward flange of the outer ring, so that the inward flange may be damaged.
An object of the present invention is to provide a universal joint having a pair of yokes, a cross shaft, and a needle bearing, and having an inward flange portion at one axial end of an annular body forming an outer ring of the needle bearing. The goal is to provide something that is unlikely to occur.

In order to solve the above problems, one embodiment of the present invention provides a universal joint having the following configurations (1) to (4).
(1) It has a pair of yokes, a cross shaft, and a needle bearing. The yoke is formed in a U-shape by a pair of arms and a base connecting these arms. A shaft insertion hole through which the shaft of the cross shaft is inserted is formed in the arm. The arm portions of the other yoke are arranged between the arm portions of one yoke such that the axes of the shaft insertion holes of the yokes are orthogonal to each other.
(2) the needle bearing, a plurality of needle rollers disposed outside the shaft portion, and an outer ring having an annular body disposed between the plurality of needle rollers and the shaft insertion hole, Having. The four shafts of the cross shaft are rotatably supported in the shaft insertion holes of the yoke by the needle bearings.
(3) The outer ring has an inward flange portion at one axial end of the annular body , which is curved and heads toward the shaft portion, and the inward flange portion is disposed on a base end side of the shaft portion. I have. The inward flange portion faces the axial end surface of the needle roller.
(4) The shaft portion has a circumferential groove in a portion arranged in the inward flange portion.

  ADVANTAGE OF THE INVENTION The universal joint of this invention is a thing which is hard to produce damage to an inward flange part.

It is a partial sectional view showing the universal joint of an embodiment. FIG. 2 is a partial cross-sectional view showing a part of the universal joint of FIG. 1 in an enlarged manner. It is a figure explaining an operation of a universal joint of an embodiment. It is a partial sectional view showing a universal joint of a reference example. FIG. 5 is a partial sectional view showing a part of the universal joint of FIG. 4 in an enlarged manner. It is a figure explaining an operation of a universal joint of a reference example. FIG. 1 is an overall configuration diagram illustrating an example of a steering device of a vehicle including an electric power steering device that applies a steering assist force on a steering column side.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the embodiments.

[Embodiment]
<Description of Configuration>
As shown in FIG. 1, the universal joint 1 of this embodiment includes a pair of yokes 2, a cross shaft 3, a needle bearing 4, and a sealing device 5.
The yoke 2 is formed in a U-shape by a pair of arm portions 21 and a base portion 22 connecting these arm portions 21. The base portion 22 of the yoke 2 is formed with a shaft insertion hole 22a through which a shaft connected by the universal joint 1 is inserted, and a bolt insertion hole 22b for fixing the shaft inserted through the shaft insertion hole 22a with a bolt. I have.

The cross shaft 3 includes a body portion 31 and four shaft portions 32 each formed in the body portion 31 in a cross shape. Each arm 21 of the yoke 2 has a shaft insertion hole 21a through which the shaft 32 of the cross shaft 3 is inserted.
The arm portion 21 of the other yoke 2 is disposed between the arm portions 21 of the one yoke 2 such that the axes of the shaft insertion holes 21a of the respective yokes 2 are orthogonal to each other. In addition, four shaft portions 32 of the cross shaft 3 are arranged via the needle bearings 4 respectively. That is, the four shaft portions 32 of the cross shaft 3 are rotatably supported by the needle bearings 4 in the shaft insertion holes 21 a of the respective yokes 2.

As shown in FIG. 2, a concave portion 33 extending in the axial direction is formed in each shaft portion 32 of the cross shaft 3, and a spider pin 35 is embedded in the concave portion 33. The head of the spider pin 35 protrudes from the tip of each shaft 32. A peripheral groove 32 a having a semicircular arc-shaped cross section is formed on a side of the shaft portion 32 near the trunk portion 31. The shaft portion 32 is divided into a distal end portion 321 at the distal end from the peripheral groove 32a and a base end portion 322 at the trunk portion 31 side from the peripheral groove 32a.
The needle bearing 4 has a plurality of needle rollers 41 arranged on the outer peripheral surface of each shaft portion 32 and an outer ring 42. The axial dimension L41 of the needle roller 41 is shorter than the dimension L32 from the distal end surface of the shaft portion 32 to the circumferential groove 32a.

The outer ring 42 includes an annular body 421, an inward flange 422, and a bottom plate 423. The inward flange 422 is located at one axial end of the annular body 421, and the bottom plate 423 is located at the other axial end of the annular body 421. It is integrated. The inward flange portion 422 has a shape that is curved in an arc shape and goes radially inward of the annular body 421. The inside diameter D422 of the inward flange portion 422 is larger than the diameter D32 of the shaft portion 32. That is, the minimum diameter of the portion of the shaft portion 32 where the peripheral groove 32a is formed is smaller than the inner diameter D422 of the inward flange portion 422.
The inward flange portion 422 is arranged at the position of the circumferential groove 32 a of the shaft portion 32. That is, the shaft portion 32 has the circumferential groove 32a in a portion arranged in the inward flange portion 422.

  The sealing device 5 includes a cored bar 51 and an elastic member 52, and the elastic member 52 has a shape in which a lip portion 52a and an annular portion 52b are integrated. The cored bar 51 is fixed to the body 31 of the cross shaft 3, and the lip 52 a of the elastic member 52 is in contact with the outer periphery of the inward flange 422 of the outer ring 42. The annular portion 52 b of the elastic member 52 is fitted to the base end 322 of the shaft 32. The space between the inward flange portion 422 and the shaft portion 32 is sealed by the sealing device 5.

<Explanation of operation>
As shown in FIG. 3, at the time of torque transmission, a force that inclines the axis acts on the shaft portion 32 of the cross shaft 3. However, in the universal joint 1 of this embodiment, since the shaft portion 32 is bent by the circumferential groove 32 a, the base end Although the axis J1 of the portion 322 is inclined, the inclination of the axis J2 of the tip 321 is suppressed. On the other hand, in the shaft portion having a constant thickness without the peripheral groove 32 a, a force is generated which pushes the needle rollers 41 toward the body 31 side as a whole, and the needle rollers 41 are attached to the inward flange portion 422. Easy to collide.
Therefore, according to the universal joint 1 of this embodiment, the needle roller 41 is prevented from colliding with the inward flange portion 422. Further, when the shaft portion 32 is bent, the inward flange portion 422 does not contact the shaft 32. That is, in the universal joint 1 of this embodiment, the inward flange portion 422 is hardly damaged.

[Reference example]
<Description of Configuration>
As shown in FIG. 4, the universal joint 1A has a pair of yokes 2, a cross shaft 3A, a needle bearing 4, and a sealing device 5.
The yoke 2 is formed in a U-shape by a pair of arms 21 and a base 22 connecting the arms 21. The base portion 22 of the yoke 2 is formed with a shaft insertion hole 22a through which the shaft connected by the universal joint 1 is inserted, and a bolt insertion hole 22b for fixing the shaft inserted through the shaft insertion hole 22a with a bolt. I have.

The cross shaft 3A includes a body portion 31 and four shaft portions 32A formed in the body portion 31 in a cross shape, respectively. Each arm 21 of the yoke 2 is formed with a shaft insertion hole 21a through which the shaft 32A of the cross shaft 3A is inserted.
The arm portion 21 of the other yoke 2 is disposed between the arm portions 21 of the one yoke 2 such that the axes of the shaft insertion holes 21a of the respective yokes 2 are orthogonal to each other. In addition, four shaft portions 32A of the cross shaft 3A are arranged via the needle bearings 4, respectively. That is, the four shaft portions 32A of the cross shaft 3A are rotatably supported by the needle bearings 4 in the shaft insertion holes 21a of the respective yokes 2.

As shown in FIG. 5, a recess 33 extending in the axial direction is formed in each shaft portion 32A of the cross shaft 3A, and a spider pin 35 is embedded in the recess 33. The head of the spider pin 35 protrudes from the tip 321 of each shaft 32A. The base end (portion near the trunk 31) 324 of the shaft 32A is formed to be thinner than the tip 321. That is, the shaft portion 32A has the circumferential groove 32b wider than the circumferential groove 32a of the above-described embodiment on the body 31 side, and the portion where the circumferential groove 32b is formed is the base end portion 324.
The needle bearing 4 includes a plurality of needle rollers 41 arranged on the outer peripheral surface of each shaft portion 32A, and an outer ring 42. The axial dimension L41 of the needle roller 41 is shorter than the dimension L321 of the tip 321 of the shaft 32A.

The outer ring 42 includes an annular body 421, an inward flange 422, and a bottom plate 423. The inward flange 422 is located at one axial end of the annular body 421, and the bottom plate 423 is located at the other axial end of the annular body 421. It is integrated. The inward flange portion 422 has a shape that is curved in an arc shape and goes radially inward of the annular body 421.
The inside diameter D422 of the inward flange portion 422 is larger than the diameter D321 of the tip portion 321 of the shaft portion 32A. That is, the diameter of the base end 324 is smaller than the inner diameter D422 of the inward flange 422. The inward flange portion 422 is disposed on the distal end portion 321 side of the proximal end portion 324 of the shaft portion 32A.

The sealing device 5 includes a cored bar 51 and an elastic member 52, and the elastic member 52 has a shape in which a lip portion 52a and an annular portion 52b are integrated. The metal core 51 is fixed to the body 31 of the cross shaft 3A, and the lip 52a of the elastic member 52 is in contact with the outer periphery of the inward flange 422 of the outer ring 42. The annular portion 52b of the elastic member 52 is fitted on the body 31 side from the position where the inward flange 422 of the base end 324 of the shaft 32A is arranged.
In this manner, the proximal end 324 formed thinner than the distal end 321 of the shaft 32A is provided with the inward flange 422 on the distal end 321 side, and the sealing device 5 on the side close to the trunk 31. ing. The sealing device 5 seals the space between the inward flange portion 422 and the shaft portion 32A.

<Explanation of operation>
As shown in FIG. 6, at the time of torque transmission, a force for tilting the axis acts on the shaft portion 32A of the cross shaft 3A. However, in this universal joint 1A, the base end 324 of the shaft 32A is thinner than the distal end 321. Although the base end 324 is bent and its axis J3 is inclined, the inclination of the axis J2 of the distal end 321 is suppressed. On the other hand, in the shaft portion having a constant thickness, a force is generated which pushes the needle rollers 41 toward the body 31 side by tilting as a whole, and the needle rollers 41 easily collide with the inward flange portion 422.
Therefore, according to the universal joint 1A, the needle roller 41 is prevented from colliding with the inward flange portion 422. Also, when the proximal end 324 of the shaft 32A is bent, the inward flange 422 does not contact the shaft 32A. That is, in the universal joint 1A, the inward flange portion 422 is not easily damaged.

[Explanation of use, etc.]
An example of an application in which a universal joint comprising a pair of yokes, a cross shaft, and a needle bearing is required to have a high torque transmission function is between an output shaft of a steering assist mechanism that applies a steering assist force to a steering system and a steering gear mechanism. Applications. An example of this use will be described below.
As shown in FIG. 7, an example of a steering apparatus for a vehicle including a column assist type electric power steering apparatus includes a steering wheel 601, a steering shaft 602, a steering column 603, a steering assist mechanism 604, and a steering gear mechanism 606. Having.

The steering shaft 602 is supported inside the steering column 603 so as to be rotatable around an axis. The steering column 603 is fixed at a predetermined position inside the vehicle cabin with a lower part inclined toward the front of the vehicle. The steering wheel 601 is fixed to a portion of the steering shaft 602 projecting upward from the steering column 603.
The steering assist mechanism 604 includes a worm speed reducer 611 that applies steering assist torque to the steering shaft 602, and an electric motor 612 that generates steering assist torque for the worm speed reducer 611. The output shaft 614 of the worm speed reducer 611 and the steering shaft 602 are connected in the steering assist mechanism 604 by a torsion bar (not shown).

An intermediate shaft 618 is connected to the output shaft 614 of the worm speed reducer 611 via a universal joint 617A. The intermediate shaft 618 is connected to a pinion shaft 619 of a rack and pinion type steering gear mechanism 606 via a universal joint 617B. A rack shaft (not shown) of the steering gear mechanism 606 is connected to a steered wheel (not shown) via a tie rod 605.
The intermediate shaft 618 includes a male shaft 618a connected to the universal joint 617A, and a female shaft 618b connected to the universal joint 617B. The male shaft 618a and the female shaft 618b are serrated.

When the driver steers the steering wheel 601, the steering device of this example detects the steering torque transmitted to the steering wheel 601 with a steering torque sensor (not shown), and detects the vehicle speed with a vehicle speed sensor (not shown). Based on the vehicle speed, a steering assist control device (not shown) drives and controls the electric motor 612 so as to generate an optimum steering assist force in a steering state.
Accordingly, the steering assist force generated by the electric motor 612 is transmitted to the steering shaft 602 via the worm speed reducer 611. By transmitting the steering assist force to the steering shaft 602 in this manner, a large steering torque is output from the output shaft 614 of the worm speed reducer 611. This steering torque is transmitted to the pinion shaft 619 of the steering gear mechanism 606 via the universal joint 617A, the intermediate shaft 618, and the universal joint 617B.

The steering gear mechanism 606 converts the rotational motion transmitted to the pinion shaft 619 into a linear motion in the vehicle width direction by a pinion constituting a steering gear and a rack meshing with the pinion. By transmitting, the steered wheels are steered.
At this time, the electric motor 612 of the steering assist mechanism 604 generates an optimal steering assist force according to the steering torque transmitted to the steering wheel 601, so that the driver can steer the steering wheel 601 lightly.
As described above, since the steering assist mechanism 604 is provided on the output side of the steering column 603, a large steering torque acts on the output shaft 614 of the worm speed reducer 611. This large steering torque is transmitted to the steering gear mechanism 606 via the universal joints 617A, 617B and the intermediate shaft 618.

When a universal joint having an inward flange portion at one axial end of an annular body forming the outer ring of the needle bearing is used as the universal joints 617A and 617B, a high load acts on the needle bearing, and the needle rollers are rolled. Repeated and strong collisions with the inward flange of the outer ring may cause damage to the inward flange portion. Therefore, by using the universal joints 1 and 1A as the universal joints 617A and 617B, damage to the inward flange portion of the universal joint is less likely to occur, and durability is improved.
That is, the durability of the steering device itself can be improved by applying the universal joint of the present invention to the connection between the shafts constituting the steering device.

  Therefore, an aspect including the universal joint according to one aspect of the present invention is a steering apparatus for a vehicle including an electric power steering apparatus in which a steering assist mechanism is provided on a steering column side. As a universal joint of a steering shaft that transmits torque to the steering shaft, there is a "steering device including the universal joint of the above-described embodiment".

DESCRIPTION OF SYMBOLS 1 Universal joint 2 Yoke 21 Arm part 21a Shaft insertion hole of arm part 22 Base 22a Base shaft insertion hole 22b Base bolt insertion hole 3 Cross shaft 3A Cross shaft 31 Cross shaft body 32 Cross shaft shaft 32A Cross shaft Shaft portion 32a Shaft portion 32 circumferential groove 32b Shaft portion 32A circumferential groove 321 Shaft end portion 322 Shaft portion 32 base end 324 Shaft portion 32A base end 33 Shaft recess 35 Spider pin 4 Needle bearing 41 Needle Roller 42 Outer Ring 421 Ring of Outer Ring 422 Inward Flange of Outer Ring 423 Bottom Plate of Outer Ring 5 Sealing Device 51 Core Metal 52 Elastic Member 52a Lip 52b Ring 6 Steering Device 617A, 617B Universal Joint 618 Middle Shaft 619 Pinion shaft 623, 624 Yoke

Claims (1)

A pair of yokes, a cross shaft, and a needle bearing,
The yoke is formed in a U-shape by a pair of arms and a base connecting these arms, and the arm has a shaft insertion hole through which the shaft of the cross shaft is inserted.
Between the arm portions of one yoke, the arm portions of the other yoke are arranged such that the axes of the shaft insertion holes of the respective yokes are orthogonal to each other,
The needle bearing has a plurality of needle rollers disposed outside the shaft portion, and an outer ring having an annular body disposed between the plurality of needle rollers and the shaft insertion hole. ,
By the needle bearing, the four shaft portions of the cross shaft are rotatably supported in the shaft insertion holes of the yoke, respectively.
The outer ring has, at one axial end of the annular body, an inward flange portion that is curved and heads toward the axial portion, and the inward flange portion is disposed on a base end side of the axial portion,
The inward flange portion faces the axial end surface of the needle roller,
The universal joint, wherein the shaft portion has a circumferential groove in a portion arranged in the inward flange portion.

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