JP2012193798A - Coupling structure for shaft and yoke of universal joint, and vehicle steering apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coupling structure for a shaft and a yoke of a universal joint capable of preventing a defect associated with the occurrence of backlash over a long period.SOLUTION: A tubular part 15 of a first yoke 12 of a first universal joint 4 has a slit 16 extended in the axial direction. With a fastening bolt 21, the tubular part 15 is fastened to a steering shaft 3. An inner circumferential surface 15a of the tubular part 15 is provided with a female serration non-forming area 23 whose center part is the slit 16 with respect to a circumferential direction R1 of the tubular part 15. A center angle θ corresponding to the female serration non-forming area 23 with a center axis line C1 of the tubular part 15 as the center is 100° to 140°.

Description

  The present invention relates to a coupling structure of a shaft and a universal joint yoke and a vehicle steering apparatus using the same.

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. As a structure for connecting a shaft such as a steering shaft, an intermediate shaft, and a pinion shaft to the yoke of the corresponding universal joint, the cylindrical portion A structure has been proposed in which a shaft that is serrated and fitted is fastened and fixed (see Patent Document 1).

  In addition, in order to form a space for accommodating burrs generated when a slit is formed in the cylindrical portion, serration teeth are formed in a range of about 40 ° on one side on both sides of the slit on the inner periphery of the cylindrical portion. It has been proposed to provide a missing tooth region (see Patent Document 2).

JP-A-9-310724 JP 2003-200238 A

By the way, in the stage before tightening the tightening bolt, the fitting between the end portion of the shaft and the cylindrical portion of the yoke of the universal joint is a clearance fit in consideration of assembly.
As shown in FIG. 6, when the cylindrical portion 72 of the yoke 71 fitted to the shaft 70 is tightened by the tightening bolt 73, the displacement of the cylindrical portion 72 is mainly a region 75 near the slit 74. The remaining portion is hardly deformed. Further, as the displacement of the cylindrical portion 72, the displacement in the tightening direction 76 (direction in which the slit 74 narrows, the axial direction of the tightening bolt 73) is dominant in the region 75 close to the slit 74.

Therefore, as the contact of the serration teeth, as shown in FIG. 7 which is an enlarged view of the D portion of FIG. 6, only in the region 75 close to the slit 74, contact is made only on the tooth surfaces 77 and 78 generally facing the tightening direction 76. Was. That is, the tooth surface of the serration was in contact with a small contact area.
Also regarding Patent Document 2, when the inner periphery of the cylindrical part is a first half-circumferential part having a slit as a central part and a second half-circumferential part facing the first half-circumferential part, As shown in FIG. 8, the contact between the serrated tooth surfaces 77 and 78 is ensured in the portion excluding the missing tooth region 79, but the serrated tooth surfaces are in contact with each other in the second half circumference portion. Even if they are not in contact with each other, they do not reach a contact state where torque transmission is possible (not shown).

  For this reason, since the contact area is small and the stress becomes high, the tooth root of the serration may be broken by long-term use. Further, when the contact surface of the teeth is worn (fretting wear), 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 noise is generated, the steering feeling is deteriorated due to rattling, and in the worst case, wear is promoted to cause idling.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a coupling structure of a shaft and a universal joint yoke that can prevent problems associated with the occurrence of rattling over a long period of time. Another object of the present invention is to provide a vehicle steering apparatus that can maintain high quality, low noise and good steering feeling over a long period of time.

  To achieve the above object, the present invention provides a universal joint yoke (3) including a shaft (3) having an end (3a) and a cylindrical portion (15) serrated to the end of the shaft. 12) and a tightening shaft (21) for fastening the cylindrical part to the shaft, the cylindrical part has a slit (16) extending in the axial direction, and the outer peripheral surface (3b) of the shaft and the cylinder Any one of the inner peripheral surfaces (15a) of the shape portion has a serration non-formation region (23; 26; 23A, 23B) having the slit as a central portion in the circumferential direction of the cylindrical portion, A central angle (θ) corresponding to the serration non-formation region centered on the central axis (C1) of the cylindrical portion is a predetermined value within a range of 100 ° to 140 °, and the yoke of the shaft and the universal joint Provide a binding structure (P) (claims) 1).

  According to the present invention, a serration non-formation region having a slit as a central portion is provided in any one of the outer peripheral surface of the shaft and the inner peripheral surface of the cylindrical portion within a range of a central angle of 100 ° to 140 °. Therefore, when the cylindrical portion is tightened by the tightening shaft, it is possible to realize strong serration fitting with close contact between the tooth surfaces in the serration fitting region facing in a direction substantially parallel to the tightening direction. it can.

  In particular, when the central angle is less than 100 °, tightening is performed only in the region close to the slit, so that the serration fitting force in the serration fitting region facing in a direction substantially parallel to the tightening direction is weakened. If the central angle exceeds 140 °, the number of engagement of serration teeth in the serration fitting region facing in a direction substantially parallel to the tightening direction is reduced. Therefore, by setting the central angle in the range of 100 ° to 140 °, it is possible to obtain a serration fitting portion fitted with a necessary and sufficient number of teeth and a strong fitting force.

  The serration non-formation region is formed on the outer peripheral surface of the shaft, and the central angle corresponding to the serration non-formation region may be a predetermined value within a range of 110 ° to 130 ° ( Claim 2). In this case, by setting the central angle corresponding to the serration non-formation region on the outer peripheral surface of the shaft to be 110 ° or more, the serration fitting force in the serration fitting region facing the direction substantially parallel to the tightening direction can be increased. Moreover, by setting the central angle to 130 ° or less, it is possible to increase the number of meshing serration teeth in the serration fitting region facing the direction substantially parallel to the tightening direction. That is, it is possible to obtain a serration fitting portion fitted with a necessary and sufficient number of teeth and a strong fitting force.

  Further, the first serration non-formation region (23A) is used as the first serration non-formation region (23A), and the first serration non-formation region is provided on one of the outer peripheral surface of the shaft and the inner peripheral surface of the cylindrical portion. In some cases, a second serration non-formation region (23B) that is opposite to is formed (claim 3). In this case, for example, in the broaching of female serration teeth, the cutting resistance can be made uniform, so that the inclination of the yoke at the time of cutting can be reduced and the machining accuracy can be improved.

The serration teeth (230; 260) adjacent to the non-serration region may form a complete tooth profile (claim 4). In this case, since the serrated tooth adjacent to the non-serrated region does not become an incomplete tooth lacking a part thereof, it is advantageous in terms of strength.
Further, in the present invention, as the structure for coupling the shaft (3) for transmitting the steering force of the steering member (2) to the yoke of the universal joint, the coupling structure (P) of the shaft and the universal joint yoke is used. A vehicle steering device (1) is provided (claim 5). According to the present invention, play due to wear hardly occurs over a long period of time, and therefore, high quality, low noise, and good steering feeling can be maintained over a long period of time.

  In the above description, the alphanumeric characters in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

1 is a schematic diagram illustrating a schematic configuration of a vehicle steering apparatus including a coupling structure of a shaft and a universal joint yoke according to a first embodiment of the present invention. It is a schematic side view of the said coupling structure. It is sectional drawing which follows the III-III line of FIG. It is sectional drawing of the coupling structure of the shaft and the yoke of a universal joint based on the 2nd Embodiment of this invention. It is sectional drawing of the coupling structure of the shaft and the yoke of a universal joint based on the 3rd Embodiment of this invention. It is a schematic sectional drawing of the coupling structure of the conventional shaft and the universal joint yoke. It is the D section enlarged view of FIG. FIG. 8 is a schematic cross-sectional view showing a state in which serrated teeth are engaged in the conventional example in which a missing tooth region is provided in the example of FIG. 7.

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 coupling structure P between a shaft and a universal joint yoke according to an embodiment of the present invention is applied. Referring to FIG. 1, a vehicle steering apparatus 1 includes a steering shaft 3 connected to a steering member 2 such as a steering wheel, and an intermediate shaft connected to the steering shaft 3 via a first universal joint 4. 5, a pinion shaft 7 connected to the intermediate shaft 5 via the second universal joint 6, and a rack 8 a meshing with the pinion 7 a provided near the end of the pinion shaft 7. And a rack shaft 8 as a steered shaft extending in the direction. The pinion shaft 7 and the rack shaft 8 constitute a turning mechanism A composed of a rack and pinion mechanism.

  The rack shaft 8 is supported in a housing 9 fixed to the vehicle body through 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 to rotate the steering shaft 3, 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.
With respect to the steering shaft 3 and the first universal joint 4, the coupling structure P of the shaft and the universal joint yoke of the present embodiment is applied. Specifically, as shown in FIG. 2, the first universal joint 4 includes a first yoke 12 to which the end 3 a of the steering shaft 3 is connected and an end 5 a of the intermediate shaft 5. A second yoke 13 and a cross shaft 14 for connecting the first yoke 12 and the second yoke 13 are provided. Serrations are formed on the outer periphery of the end 3 a of the steering shaft 3.

Referring to FIGS. 2 and 3, the first yoke 12 has a cylindrical portion 15 to which the end portion 3 a of the steering shaft 3 is fitted. As shown in FIG. 3, the cylindrical portion 15 is provided with a slit 16 extending in the axial direction. The first yoke 12 has a pair of tabs 17 and 18 on both sides of the slit 16.
A tightening bolt 21 as a tightening shaft is inserted into bolt insertion holes 19 and 20 provided in the tabs 17 and 18. The pair of tabs 17 and 18 are tightened between the nut 22 engaged with the tip 21b of the tightening bolt 21 and the head 21a of the tightening bolt 21, whereby the end 3a of the steering shaft 3 is cylindrical. It is tightened in the part 15.

  A female serration is provided on the inner peripheral surface 15 a of the cylindrical portion 15, while a female serration non-formation region 23 (missing tooth region) having the slit 16 as a central portion in the circumferential direction R <b> 1 of the cylindrical portion 15 is provided. It has been. The central angle θ corresponding to the female serration non-formation region 23 centered on the central axis C1 of the cylindrical portion 15 is a predetermined value within a range of 100 ° to 140 °, for example, 100 °, for example, 120 °, It is set to 140 °.

  According to the present embodiment, the female serration non-formation region 23 having the slit 16 as the central portion is provided on the inner peripheral surface 15a of the cylindrical portion 15 of the first yoke 12 of the first universal joint 4, and the female Since the central angle θ corresponding to the serration non-formation region 23 is set to a predetermined value within the range of 100 ° to 140 °, when the cylindrical portion 15 is tightened with the tightening bolt 21, the tightening direction X1 (the tightening bolt 21 In the serration fitting regions 24 and 25 facing the direction Y1 parallel to the direction Y1 (or the direction substantially parallel to the fastening direction X1). Can be realized.

  That is, when the central angle θ is less than 100 °, the fastening is performed only in the region close to the slit 16, so that the serration fitting that faces the direction Y1 parallel to the fastening direction X1 (or the direction substantially parallel to the fastening direction X1). The serration fitting force in the regions 24 and 25 is weakened. When the central angle θ exceeds 140 °, the serration teeth mesh in the serration fitting regions 24 and 25 facing the direction Y1 parallel to the tightening direction X1 (or the direction substantially parallel to the tightening direction X1). The number decreases. Therefore, by setting the central angle θ in the range of 100 ° to 140 °, the serration fitting regions 24 and 25 fitted with a necessary and sufficient number of teeth and a strong fitting force can be obtained.

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 FIG. 4, it is preferable that the female serration teeth 230 adjacent to the female serration non-formation region 23 have a complete tooth profile. This is because the female serration teeth 230 adjacent to the female serration non-formation region 23 do not become incomplete teeth lacking a part thereof, which is advantageous in terms of strength.

  Next, FIG. 4 shows a second embodiment of the present invention. Referring to FIG. 4, this embodiment is mainly different from the embodiment of FIG. 3 in that the inner peripheral surface 15a of the cylindrical portion 15 of the first yoke 12 as in the embodiment of FIG. The male serration non-formation region 26 is provided on the outer peripheral surface 3b of the steering shaft 3 in place of the female serration non-formation region 23 provided in FIG. In the present embodiment, the central angle θ corresponding to the male serration non-formation region 26 is preferably set to a predetermined value within the range of 100 ° to 130 °. Moreover, it is preferable that the male serration tooth 260 adjacent to the male serration non-formation region 26 has a complete tooth profile.

In the constituent elements of the present embodiment, the same constituent elements as those in the embodiment of FIG. 3 are denoted by the same reference numerals.
Also in the present embodiment, when the tubular portion 15 is tightened by the tightening bolt 21, the direction Y1 (or the parallel to the tightening direction X1) is parallel to the tightening direction X1 (corresponding to the axial direction of the tightening bolt 21). In the serration fitting regions 24 and 25 facing (direction), it is possible to realize strong serration fitting in which the contact between the tooth surfaces is close.

  In particular, by setting the central angle θ corresponding to the male serration non-formation region 26 of the outer peripheral surface 3b of the steering shaft 3 to 110 ° or more, the direction Y1 parallel to the tightening direction X1 (or the direction substantially parallel to the tightening direction X1). The serration fitting force in the serration fitting regions 24 and 25 that face each other can be increased. In addition, by setting the central angle θ to 130 ° or less, the serration teeth are engaged in the serration fitting regions 24 and 25 facing the direction Y1 parallel to the tightening direction X1 (or the direction substantially parallel to the tightening direction X1). The total number can be increased. That is, it is possible to obtain a serration fitting that is fitted with a necessary and sufficient number of teeth and a strong fitting force.

In addition, when the male serration tooth 260 adjacent to the male serration non-formation region 26 has a complete tooth profile, the male serration tooth 260 adjacent to the male serration non-formation region 26 is partially missing. This is advantageous in terms of strength.
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.

In the present embodiment, the male serration non-formation region 26 is defined as the first male serration non-formation region on the outer peripheral surface 3b of the steering shaft 3, and the tightening direction with respect to the first male serration non-formation region You may make it provide the 2nd male serration non-formation area | region (not shown) facing in the direction orthogonal to X1.
Next, FIG. 5 shows a third embodiment of the present invention. Referring to FIG. 5, the present embodiment differs from the embodiment of FIG. 3 on the inner peripheral surface 15 a of the cylindrical portion 15 of the first yoke 12 of the first universal joint 4. The first female serration non-formation region 23A corresponding to the female serration non-formation region 23 of the embodiment and the second female serration non-formation region 23B facing the first female serration non-formation region 23A are provided. In the point.

The first female serration non-formation region 23A and the second female serration non-formation region 23B are in a direction Z1 orthogonal to the fastening direction X1. In the constituent elements of the present embodiment, the same constituent elements as those in the embodiment of FIG. 3 are denoted by the same reference numerals.
The central angle θ2 corresponding to the second female serration non-formation region 23B is set to a predetermined value within the range of 100 ° to 140 °, similarly to the central angle θ corresponding to the first female serration non-formation region 23A. . Providing the second female serration non-formation region 23B facing the first female serration non-formation region 23A has the following advantages. That is, in the broaching of the female serration teeth, the cutting resistance can be made uniform, so that the inclination of the yoke at the time of cutting can be reduced and the machining accuracy can be improved. From this viewpoint, it is preferable that the value of the central angle θ2 is equal to the value of the central angle θ.

  Also in the present embodiment, when the tubular portion 15 is tightened by the tightening bolt 21, the direction Y1 (or the parallel to the tightening direction X1) is parallel to the tightening direction X1 (corresponding to the axial direction of the tightening bolt 21). In the serration fitting regions 24 and 25 facing (direction), it is possible to realize strong serration fitting in which the contact between the tooth surfaces is close. 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.

  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, but the present invention is a shaft that transmits a steering force. Any one of the steering shaft 3, intermediate shaft 5 and pinion shaft 7 can be applied to a structure in which the corresponding universal joints 4 and 6 are coupled to corresponding yokes. In addition, various modifications can be made within the scope of the claims of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle steering device, 2 ... Steering member, 3 ... Steering shaft, 4 ... 1st universal joint, 5 ... Intermediate shaft, 6 ... 2nd universal joint, 7 ... Pinion shaft, 8 ... Rack shaft, A ... Steering mechanism, P ... Coupling structure (of shaft and universal joint yoke), 12 ... First yoke, 13 ... Second yoke, 14 ... Cross shaft, 15 ... Cylindrical part, 15a ... (Cylindrical part) ) Inner peripheral surface, 16 ... slit, 17, 18 ... tab, 19, 20 ... bolt insertion hole, 21 ... clamping bolt (tightening shaft), 23 ... female serration non-formation region, 230 ... female serration tooth (serration non-formation) Serration teeth adjacent to the region), 23A ... first female serration non-formation region, 23B ... second female serration non-formation region, 24, 25 ... (facing in a direction parallel to the tightening direction) Serration fitting area, 26 ... male serration non-formation area, 260 ... male serration tooth (serration teeth adjacent to the serration non-formation area), X1 ... tightening direction, Y1 ... direction parallel to tightening direction, Z1 ... tightening direction Are orthogonal directions, θ, θ2, ... center angle

Claims (5)

A shaft having an end;
A universal joint yoke including a cylindrical portion serrated to the end of the shaft;
A fastening shaft for fastening the tubular part to the shaft,
The cylindrical part has a slit extending in the axial direction,
Either one of the outer peripheral surface of the shaft and the inner peripheral surface of the cylindrical portion has a serration non-formation region having the slit as a central portion in the circumferential direction of the cylindrical portion, and the center of the cylindrical portion A joint structure of a shaft and a universal joint yoke, wherein a central angle corresponding to the serration non-formation region centered on an axis is a predetermined value within a range of 100 ° to 140 °. In claim 1, the serration non-formation region is formed on the outer peripheral surface of the shaft,
A coupling structure of a shaft and a universal joint yoke, wherein a central angle corresponding to the serration non-formation region is a predetermined value within a range of 110 ° to 130 °.   3. The first serration non-formation region according to claim 1 or 2, wherein the first serration non-formation region is defined as a first serration non-formation region, and one of the outer peripheral surface of the shaft and the inner peripheral surface of the cylindrical portion is provided. A coupling structure of a shaft and a universal joint yoke, in which a second serration non-formation region facing the formation region is formed.   The joint structure of a shaft and a universal joint yoke according to any one of claims 1 to 3, wherein the serration teeth adjacent to the non-serration region have a complete tooth profile.   5. A vehicle steering system in which the shaft and universal joint yoke structure according to any one of claims 1 to 4 is used as a structure for coupling a shaft for transmitting a steering force of a steering member to a universal joint yoke. apparatus.

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