JP2014101969A - Yoke joint structure of universal joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joint structure for a yoke of a shaft and a universal joint capable of preventing, for a long period of time, a failure from occurring along with the occurrence of backlash.SOLUTION: A yoke joint structure of a universal joint 4 comprises: a shaft 3 having an end: a cylindrical part 15 fitted to the end 3a of the shaft 3; a yoke 12 integrated with the cylindrical part 15; a serration fitting part formed between the shaft 3 and the cylindrical part 15, and for serration-fitting the shaft and the cylindrical part each other; and a joint structure for joining the shaft 3 and the yoke 12 so that the shaft and the yoke do not separate from each other. The serration fitting part has a tapered shape. The joint structure includes a screw member 20 fitted to the cylindrical part 20 and the shaft 3, screw parts formed between the cylindrical part 15 and the screw member 20, and configured to be screwed to each other, a stage 3c formed on the outer periphery of the shaft 3, and a fixing part formed on the screw member and engaged with the stage 3c in one direction in the axial direction.

Description

  The present invention relates to a universal joint yoke coupling structure used in a rack and pinion type steering device.

  In general, in a vehicle steering apparatus, a rotational force from a steering wheel is transmitted to a steering mechanism such as a rack and pinion mechanism via a steering shaft, an intermediate shaft (intermediate shaft), etc. To steer.

  The upper end of the intermediate shaft is connected to the steering shaft via a universal joint, and the lower end of the intermediate shaft is connected to the pinion shaft via a universal joint. In order to connect the steering shaft or pinion shaft to the universal joint yoke, the shaft is serrated and fitted into a cylindrical part integrated with the universal joint yoke so that the slit width of the half of the cylindrical part becomes narrower. There has been proposed a structure in which a shaft that is serrated and fitted to a cylindrical portion is fastened and fixed by fastening with a fastening bolt (see Patent Document 1).

JP-A-9-310724

  In the stage before tightening with the tightening bolt, the serration fitting of the end portion of the shaft and the cylindrical portion is a clearance fit in consideration of assembly. Therefore, when tightened with a tightening bolt, as the displacement of the cylindrical portion, the region close to the slit is mainly deformed, and the remaining portion is hardly deformed. Therefore, the serration teeth contact each other only in the region close to the slit. That is, the tooth surface of the serration was in contact with a small contact area.

  For this reason, the contact area is small, the stress becomes high, and the tooth contact surface wears (fretting wear) due to long-term use, so that the axial force of the tightening bolt may be reduced and the fastening may be loosened. . In that case, there is a possibility that an abnormal noise due to rattling occurs, or that the steering feeling deteriorates due to rattling.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a universal joint yoke coupling structure that can prevent problems associated with the occurrence of rattling over a long period of time.

  In order to achieve the above object, the present invention provides a shaft having an end portion, a cylindrical tubular portion fitted to the end portion of the shaft, a yoke integrated with the cylindrical portion, In a yoke coupling structure of a universal joint, which is formed between a shaft and the cylindrical portion, and includes a serration fitting portion that serration-fits them together, and a coupling mechanism that detachably couples the shaft and the yoke to each other. The serration fitting portion has a taper shape, and the coupling mechanism is formed between the cylindrical portion and the screw member and the screw member fitted to the cylindrical portion and the shaft, and is screwed together. The gist consists of a threaded portion, a stepped portion formed on the outer periphery of the shaft, and a fastening portion that is engaged with the stepped portion in one direction in the axial direction and formed on the screw member.

  According to the present invention, the cylindrical portion of the shaft and the universal joint yoke are taper-fitted together with the serration fitting, while the cylindrical portion of the universal joint yoke and the threaded portion between the screw members are mutually connected. Since it is screwed in the direction and pressed in the taper fitting direction via the fastening part and the step part, the contact area of the tooth surface of the serration between the shaft and the cylindrical part is increased. Therefore, it is possible to provide a universal joint yoke coupling structure that can prevent problems associated with the occurrence of rattling over a long period of time.

  The contact area of the tooth surface of the serration is increased, and a universal joint yoke coupling structure capable of preventing problems associated with the occurrence of rattling over a long period of time can be provided.

The schematic diagram which shows schematic structure of the steering apparatus for vehicles containing the yoke coupling structure of the universal joint which concerns on embodiment of this invention. The schematic side view which made the partial joint figure of the yoke joint structure of the universal joint which concerns on embodiment of this invention

Preferred embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic diagram showing a schematic configuration of a vehicle steering apparatus 1 to which a universal joint yoke coupling structure P according to an embodiment of the present invention is applied. Referring to FIG. 1, a vehicle steering apparatus 1 is connected to a steering shaft (hereinafter referred to as a shaft) 3 connected to a steering member 2 such as a steering wheel, and the shaft 3 via a first universal joint 4. It has an intermediate shaft 5, a pinion shaft 7 connected to the intermediate shaft 5 via a second universal joint 6, and a rack shaft 8 that meshes with the pinion shaft 7 and extends in the left-right direction of the automobile. The pinion shaft 7 has a pinion 7a provided near the end, and the rack shaft 8 has a rack 8a that meshes with the pinion 7a. The pinion 7a and the rack 8a mesh with each other. The pinion shaft 7 and the rack shaft 8 constitute a turning mechanism A including a rack and pinion mechanism.

The rack shaft 8 is supported in a housing 9 fixed to the vehicle body via a rack bush 50 which is a sliding bearing so as to be linearly reciprocable along the axial direction W1. Both end portions of the rack shaft 8 protrude to both sides of the housing 9, and tie rods 10 are coupled to the respective end portions. Each tie rod 10 is connected to a corresponding steered wheel 11 via a corresponding knuckle arm (not shown).
When the steering member 2 is operated and the steering shaft 3 is rotated, this rotation is converted into a linear motion of the rack shaft 8 along the left-right direction of the automobile by the pinion 7a and the rack 8a. Thereby, the turning of the steered wheel 11 is achieved.

  The present invention is applied to the coupling structure P between the shaft 3 of the present embodiment and the first yoke 12 of the first universal joint 4 with respect to the shaft 3 and the first universal joint 4. Specifically, as shown in FIG. 2, the first universal joint 4 includes a first yoke 12 to which the end 3a of the shaft 3 is connected, and a first yoke 12 to which the end 5a of the intermediate shaft 5 is connected. 2 yokes 13, and a cross shaft 14 that connects the first yoke 12 and the second yoke 13. The present invention includes a first yoke 12, a shaft 3 having serrations 3b formed on the outer periphery of the end portion 3a, and a screw member 20 that fastens the first yoke and the shaft 3 in the axial direction. It is characterized by being.

  A cylindrical tubular portion 15 is integrated with the first yoke 12, and a tapered female serration 15 a to which the end portion 3 a of the shaft 3 is fitted is formed on the inner peripheral surface of the tubular portion 15. An external thread portion 15 b is provided on the outer peripheral surface of the cylindrical portion 15.

  The screw member 20 is formed in a cylindrical shape, and a female screw portion 20b that is screwed with a male screw portion 15b on the outer periphery of the cylindrical portion 15 is formed on the inner peripheral portion. The male screw portion 15b and the female screw portion 20b constitute a screw portion that is screwed together. The screw member 20 further includes a retaining portion 20a protruding radially inward from the inner periphery, and presses the annular step portion 3c of the shaft 3 in order to secure the shaft 3 in the axial direction W1.

  In addition, a tool engaging portion 20 d that is engaged with a tool for rotating the screw member 20 is formed on the outer peripheral portion of the screw member 20. The tool engaging portion 20d has a polygonal cross section such as a hexagon.

  The shaft 3 is formed with a tapered male serration 3b at the end 3a, and a step 3c is formed circumferentially on the axial extension of the male serration 3b. The female serration 15a and the male serration 3b constitute a serration fitting portion that is serrated to each other.

  Next, the operation of coupling the first yoke 12 of the first universal joint 4 to the shaft 3 will be described based on the configuration described above. With the screw member 20 loosely fitted to the shaft 3 from the upper side on the steering wheel 2 side, the male serration portion 3b of the shaft 3 is connected to the cylindrical portion 15 of the first yoke 12 on the first universal joint 4 side. The female serration portion 15a is serrated. The tool is engaged with the tool engaging portion 20d, and the screw member 20 is rotated together with the tool. The male screw portion 15b is screwed into the female screw portion 20b, and the screw member 20 rotates in the axial direction toward the intermediate shaft 5 side while rotating. When the fastening portion 20a of the screw member 20 is engaged with the step portion 3c and the screw member 20 is further rotated, the first yoke 12 moves in the axial direction toward the shaft 3 side. When the male serration 3b is completely serrated and fitted into the female serration 15a, the taper of the female serration 15a and the male serration 3b prevents the first yoke 12 from moving in the axial direction toward the shaft 3, and the first serration 3b The yoke 12 is securely coupled to the shaft 3 and cannot be detached.

  According to the present embodiment, the cylindrical portion 15 of the first yoke 12 of the shaft 3 and the universal joint 4 is taper-fitted and simultaneously serrated, while the cylinder of the first yoke of the universal joint 4 is used. Since the male screw portion 15b of the shaped portion 15 and the female screw portion 20b between the screw members 20 are screwed together in the axial direction and pressed in the direction of taper fitting through the fastening portion 20a and the stepped portion 3c, the shaft The contact area between the tooth surfaces of the serrations 3 and the cylindrical portion 15 is increased, and the first yoke 12 is reliably coupled to the shaft 3 and cannot be detached. Therefore, it is possible to provide a universal joint yoke coupling structure that can prevent problems associated with the occurrence of rattling over a long period of time.

  Further, according to the vehicle steering apparatus 1 in which the coupling structure P is applied to the coupling between the steering shaft 3 and the first yoke 12 of the first universal joint 4, it is difficult for rattling due to wear to occur over a long period of time. Low noise and good steering feeling can be maintained over a long period of time.

  Moreover, in order to seal between the internal thread part 20b of the screw member 20, and the external thread part 15b of the cylindrical part 15, by using seal members, such as a liquid packing, between these, the penetration | invasion of the water | moisture from the outside It is preferable that the serration fitting portion constituted by the female serration 15a and the male serration 3b can be prevented from being rusted and play due to wear is less likely to occur over a longer period.

  In each of the above embodiments, the coupling structure P of the present invention is applied to the coupling structure of the steering shaft 3 and the first yoke 12 of the first universal joint 4. However, the present invention includes other embodiments as follows. This can be applied to a connection structure between the intermediate shaft 5 and the second yoke 13 of the first universal joint 4. Further, the present invention can be applied to a structure in which any one of the intermediate shaft 5 and the pinion shaft 7 is coupled to a yoke corresponding to the corresponding universal joint 6.

DESCRIPTION OF SYMBOLS 1 ... Steering device for vehicles, 2 ... Steering member, 3 ... Steering shaft, 3a ... End part (of steering shaft), 3b ... Serration part (steering shaft), 3c ... Step part (steering shaft),
DESCRIPTION OF SYMBOLS 4 ... First universal joint, 5 ... Intermediate shaft, 6 ... Second universal joint, 7 ... Pinion shaft, 8 ... Rack shaft, A ... Steering mechanism, P ... Coupling (shaft and universal joint yoke) Structure: 12 ... 1st yoke, 13 ... 2nd yoke, 14 ... Cross shaft, 15 ... Cylindrical part, 15a ... Inner peripheral surface of (cylindrical part), 15b ... Male thread part (of cylindrical part), 20 ... Screw member, 20a ... Fastening portion (of the screw member), 20b ... Female screw portion (of the screw member)

Claims (1)

A shaft having an end, a cylindrical tubular part fitted to the end of the shaft, a yoke integrated with the cylindrical part, and formed between the shaft and the cylindrical part, In the yoke coupling structure of a universal joint comprising a serration fitting portion for serration fitting them together and a coupling mechanism for detachably coupling the shaft and the yoke to each other, the serration fitting portion has a taper shape, The coupling mechanism is formed on the outer periphery of the shaft, a screw member that is fitted to the cylindrical portion and the shaft, a screw portion that is formed between the cylindrical portion and the screw member, and is screwed together. A universal joint yoke coupling structure, comprising: a step portion; and a step portion that is engaged with the step portion in one direction in the axial direction and formed on a screw member.

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