JP2018100715A - Coupling structure of shaft and yoke - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a holding force of serration fitment at an opposing part opposing a slit in a radial direction of a cylinder part at an internal peripheral face of the cylinder part of a yoke, in a coupling structure of a shaft and the yoke.SOLUTION: A fastening bolt 40 makes a pair of adjacent parts 22 which are adjacently arranged at both sides of a slit 21 with respect to a peripheral direction Z of a cylinder part 20 approximate each other, and fastens the cylinder part 20 to a steering shaft 2. A pair of cam faces 70 formed at a pair of the adjacent parts 22 are inwardly inclined toward an opposing part 23 opposing the slit 21 in a radial direction R of the cylinder part 20 at an internal peripheral face 20a of the cylinder part 20. When a pair of the adjacent parts 22 approximate each other, a pair of the cam faces 70 energize an interposition member 50 interposed between a pair of the cam faces 70 and an external peripheral face 2c of the steering shaft 2 toward the opposing part 23.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a coupling structure of a shaft and a yoke.

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, intermediate shaft, or pinion shaft to the yoke of the corresponding universal joint, a cylindrical portion with a slit of the universal joint yoke is tightened with a fastening bolt that crosses the slit. Generally, a structure in which the cylindrical portion is fastened and fixed to a shaft that is serrated and fitted to the cylindrical portion.

  When the tightening bolt is tightened, the pair of portions arranged on both sides of the slit in the tubular portion in the circumferential direction of the tubular portion is mainly deformed. The holding force is high, and the serration fitting holding force tends to be weak with respect to the shaft in other portions (particularly, the opposing portion facing the slit and the radial direction of the cylindrical portion in the inner periphery of the cylindrical portion).

  In view of this, a technique has been proposed in which serration non-formation regions (that is, missing tooth regions) are provided on both sides of the pair of portions on the inner periphery of the cylindrical portion (see, for example, Patent Document 1).

JP 2014-169732 A

However, there is still a problem in that the holding force for serration fitting with respect to the shaft is weak at the facing portion facing the slit in the radial direction of the cylindrical portion on the inner periphery of the cylindrical portion.
An object of the present invention is to provide a shaft-yoke coupling structure capable of improving the holding force of serration fitting at a facing portion facing the slit in the radial direction with respect to the slit on the inner periphery of the tubular portion. That is.

  The invention according to claim 1 is a shaft (2) having an outer peripheral surface (2c) on which a male serration (MS) is formed, and an inner peripheral surface on which a female serration (FS) meshed with the male serration is formed ( 20a) a cylindrical portion (20) fitted to the shaft, the slit (21) extending in the axial direction (X), and the slit in the circumferential direction (Z) of the cylindrical portion A cylindrical shape having a pair of adjacent portions (22) adjacent to both sides and a facing portion (23) facing the slit in the radial direction (R) with respect to the slit on the inner peripheral surface of the cylindrical portion. The universal joint yoke (31), and the slit in the orthogonal direction (Y) orthogonal to the axial direction of the cylindrical portion, and the pair of adjacent portions are brought close to each other to bring the cylindrical portion into the A fastening shaft (40) to be fastened to the shaft; And a pair of cam surfaces (70; 70B) inclined inward toward each other as viewed from the axial direction of the cylindrical portion, and the outer periphery of the pair of cam surfaces and the shaft An interposition member (50; 50, 50A; 50B) interposed between the pair of cam surfaces, and the pair of cam surfaces, when the pair of adjacent portions are close to each other, Provided is a joint structure (P; PA; PB) of a shaft and a yoke configured to generate a biasing force biasing toward the shaft.

In addition, although the alphanumeric character in a parenthesis represents the corresponding component etc. in embodiment mentioned later, this does not mean that this invention should be limited to those embodiment as a matter of course. The same applies hereinafter.
According to a second aspect of the present invention, the interposition member may include a pair of driven surfaces (51; 51B) that are in sliding contact with the pair of cam surfaces, respectively.

As in claim 3, a holding recess (80; 80, 80A) for holding the interposition member may be formed on the outer peripheral surface of the shaft.
According to a fourth aspect of the present invention, at least one of the inner peripheral surface of the cylindrical portion and the outer peripheral surface of the shaft is disposed on both sides of the interposed member with respect to the circumferential direction, and a pair of notches provided with no serration teeth A tooth region (90) may be included.

  In the invention of claim 1, when the pair of adjacent portions on both sides of the slit are brought close to each other by tightening with the tightening shaft, the pair of cam surfaces provided in the pair of adjacent portions are interposed via the interposition member, The shaft is urged on the inner peripheral surface of the cylindrical portion to a facing portion facing the slit and the radial direction of the cylindrical portion. For this reason, the holding force of the serration in the facing portion can be increased, and the fastening force as the entire coupling structure can be increased.

In the invention of claim 2, when tightening with the tightening shaft, the pair of cam surfaces inclined inward are brought close to each other while being in sliding contact with the pair of driven surfaces. For this reason, a biasing force can be generated without loss by the pair of cam surfaces.
In the invention of claim 3, since the interposition member is held in the holding recess on the outer peripheral surface of the shaft, the position and posture of the interposition member are stabilized, and therefore the interposition member can be urged stably by the pair of cam surfaces. it can.

  According to the fourth aspect of the present invention, the missing tooth regions are provided on both sides of the interposed member in the circumferential direction of the cylindrical portion. For this reason, it is possible to intensively apply a tightening force by the tightening shaft to the pair of cam surfaces and strongly press the shaft against the opposing portion of the cylindrical portion via the interposed member biased by the pair of cam surfaces. it can.

1 is a schematic diagram illustrating a schematic configuration of a vehicle steering apparatus to which a shaft-yoke coupling structure according to a first embodiment of the present invention is applied. It is a schematic side view of the coupling structure of FIG. (A) is a schematic sectional drawing of the joint structure cut | disconnected along the III-III line | wire of FIG. (B) is typical sectional drawing of the structure of the periphery of an interposed member. FIG. 4 is a schematic cross-sectional view of the bonding structure taken along line IV-IV in FIG. 2. In 1st Embodiment, it is a schematic sectional drawing of the joint structure cut | disconnected along the axial direction of a steering shaft. It is a schematic sectional drawing of the coupling structure of the 2nd Embodiment of this invention. It is typical sectional drawing of the coupling structure of the 3rd Embodiment of this invention.

Preferred embodiments of the present invention will be described with reference to the accompanying drawings.
(First embodiment)
FIG. 1 is a schematic diagram showing a schematic configuration of a vehicle steering apparatus 1 to which a shaft-yoke coupling structure P (hereinafter also simply referred to as a coupling structure P) according to a first embodiment of the present invention is applied. As shown in FIG. 1, the vehicle steering apparatus 1 includes a steering shaft 2, a first universal joint 3, an intermediate shaft 4, a second universal joint 5, a pinion shaft 6, and a steered shaft. And a rack shaft 7.

  A steering member 8 such as a steering wheel is connected to one axial end portion 2 a of the steering shaft 2. The other end portion 2 b in the axial direction of the steering shaft 2 is connected to one end portion 4 a in the axial direction of the intermediate shaft 4 via the first universal joint 3. The other end portion 4 b in the axial direction of the intermediate shaft 4 is connected to one end portion 6 a of the pinion shaft 6 through the second universal joint 5.

  A pinion 6c provided at the other axial end portion 6b of the pinion shaft 6 and a rack 7a provided on the rack shaft 7 are meshed with each other. The rack shaft 7 is supported by a housing 9 fixed to the vehicle body so as to be movable in the axial direction (corresponding to the left-right direction of the vehicle). Both end portions of the rack shaft 7 protrude to both sides of the housing 9, and tie rods 10 are connected 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 8 is operated and the steering shaft 2 is rotated, the pinion shaft 6 is rotated. As the pinion shaft 6 rotates, the rack shaft 7 is moved in the axial direction, and thereby the turning of the steered wheels 11 is achieved.

  For the steering shaft 2 and the first universal joint 3, the coupling structure P of the present embodiment is applied. Specifically, as shown in FIG. 2, the first universal joint 3 includes a first yoke 31, a second yoke 32, and a cross shaft 33. The other end 2 b of the steering shaft 2 is connected to the first yoke 31. One end 4 a of the intermediate shaft 4 is connected to the second yoke 32. The cross shaft 33 connects the first yoke 31 and the second yoke 32.

  The coupling structure P includes the steering shaft 2, the first yoke 31 of the first universal joint 3, a fastening bolt 40 as a fastening shaft, and an interposed member 50. The first yoke 31 includes a tubular portion 20 as a base portion and a pair of arm portions 60 extending from the tubular portion 20 in the axial direction X of the tubular portion 20. The tubular portion 20 is fitted to the other end 2 b of the steering shaft 2. Each of the pair of arm portions 60 is formed with a connection hole 61 to which a corresponding shaft portion of the cross shaft 33 is connected.

  3A is a schematic cross-sectional view of the coupling structure P cut along the line III-III in FIG. 2, and FIG. 3B is a schematic diagram of the structure around the interposed member 50. In FIG. 3B, hatching indicating a cross section is omitted for simplification. FIG. 4 is a schematic cross-sectional view of the bonding structure P cut along the line IV-IV in FIG. FIG. 5 is a schematic cross-sectional view of the coupling structure P cut along the axial direction of the steering shaft 2.

As shown in FIGS. 3A and 4, a male serration MS is formed on the outer peripheral surface 2 c of the other end 2 b of the steering shaft 2. A female serration FS meshed with the male serration MS is formed on the inner peripheral surface 20 a of the cylindrical portion 20.
The tubular portion 20 includes a slit 21, a pair of adjacent portions 22, and a facing portion 23. As shown in FIG. 5, the slit 21 extends in the axial direction X of the cylindrical portion 20 (corresponding to the axial direction of the steering shaft 2). As shown in FIG. 3A and FIG. 4, the pair of adjacent portions 22 are disposed adjacent to both sides of the slit 21 with respect to the circumferential direction Z of the tubular portion 20. That is, the pair of adjacent portions 22 has a wall surface 22a that partitions the slit 21 therebetween. The facing portion 23 is a portion facing the slit 21 in the radial direction R of the tubular portion 20 on the inner peripheral surface 20 a of the tubular portion 20.

  The fastening bolt 40 is the axial direction X of the cylindrical portion 20 [the direction perpendicular to the paper surface in FIG. 3 (a) and FIG. Cross also the slit 21 in the orthogonal direction Y orthogonal to FIG. As shown in FIGS. 3A and 4, the tightening bolt 40 includes a shaft portion 41 and a head portion 42 provided at one end portion 41 a of the shaft portion 41. A male screw portion 43 is formed in a range of a predetermined length from the other end portion 41 b of the shaft portion 41. The fastening bolt 40 is screwed into the screw hole 22c provided in the other adjacent portion 22 through the insertion hole 22b provided in the one adjacent portion 22, and the male screw portion 43 is formed on the inner peripheral surface of the screw hole 22c. It is screwed into the female thread.

When the fastening bolt 40 is screwed in, the pair of adjacent portions 22 are brought close to each other, whereby the other end portion 2 b of the steering shaft 2 is tightened in the cylindrical portion 20. A pair of cam surfaces 70 are provided in the pair of adjacent portions 22. The pair of cam surfaces 70 are surfaces extending in parallel with the axial direction X of the cylindrical portion 20, and are inclined inward toward the facing portion 23.
The interposed member 50 is interposed between the pair of cam surfaces 70 and the outer peripheral surface 2 c of the steering shaft 2. The interposition member 50 is formed in, for example, a substantially pentagonal column shape that is long in the axial direction X of the cylindrical portion 20 [direction orthogonal to the paper surface in FIG. 3A]. The interposition member 50 includes a pair of driven surfaces 51, a pressing surface 52, and a pair of regulated surfaces 53 as surfaces extending in the axial direction X in the assembled state to the coupling structure P.

  As shown in FIG. 3B, the pair of driven surfaces 51 are inclined in the opposite direction to the pair of cam surfaces 70 at an inclination angle equal to the inclination angle of the pair of cam surfaces 70. Surface contact with 70. The pressing surface 52 is disposed on the opposite side of the pair of driven surfaces 51 and presses the outer peripheral surface 2 c of the steering shaft 2. The pressing surface 52 is a surface parallel to the central axis C <b> 1 of the tightening bolt 40 in the assembled state of the interposition member 50 to the coupling structure P. The pair of regulated surfaces 53 are surfaces that are orthogonal to the pressing surface 52 and are opposed to the circumferential direction Z of the tubular portion 20.

The inner peripheral surface 20 a of the tubular portion 20 has a pair of missing tooth regions 90 disposed on both sides of the interposed member 50 in the circumferential direction Z. The missing tooth region 90 is a region where the male serration MS is not provided.
As shown in FIGS. 4 and 5, the outer peripheral surface 2 c of the steering shaft 2 is formed with a circumferential groove 2 d with which the shaft portion 41 of the tightening bolt 40 is engaged. Further, as shown in FIGS. 3A, 3 </ b> B, and 5, a holding recess 80 that holds the interposition member 50 is formed on the outer peripheral surface 2 c of the steering shaft 2. As shown in FIG. 5, the holding recess 80 is a groove extending a predetermined length in a direction away from the distal end side of the steering shaft 2 with respect to the circumferential groove 2 d. As shown in FIG. 3B, the holding recess 80 includes a bottom 81 and a pair of inner walls 82 as surfaces extending in the axial direction of the steering shaft 2. The bottom 81 receives the pressing surface 52 of the interposed member 50. The pair of inner wall portions 82 abuts against the pair of regulated surfaces 53 of the interposed member 50, thereby restricting movement of the interposed member 50 in the circumferential direction Z.

When assembling the coupling structure P, the other end 2b of the steering shaft 2 is inserted into the cylindrical portion 20 of the first yoke 31, and then the inner peripheral surface 20a of the cylindrical portion 20 as shown in FIG. And the interposition member 50 is inserted between the outer peripheral surface 2c of the steering shaft 2 and the holding recess 80. Thereafter, the tightening bolt 40 is tightened.
According to the present embodiment, as shown in FIG. 3A, when the pair of adjacent portions 22 on both sides of the slit 21 in the tubular portion 20 are brought close to each other by tightening with the tightening bolt 40, a pair of A pair of cam surfaces 70 provided in the adjacent portion 22 opposes the steering shaft 2 in the radial direction R of the tubular portion 20 with respect to the slit 21 on the inner peripheral surface 20a of the tubular portion 20 via the interposition member 50. The opposing portion 23 is energized. For this reason, the holding force of the serrations MS and FS in the facing portion 23 can be increased, and the fastening force of the entire coupling structure P can be increased.

  Further, as shown in FIG. 3B, when tightening with the tightening bolt 40, the pair of cam surfaces 70 that incline toward each other toward the facing portion 23 are in sliding contact with the pair of driven surfaces 51. While approaching smoothly. For this reason, a biasing force can be generated by the pair of cam surfaces 70 without loss. Specifically, the interposing member 50 is pressed toward the opposing portion 23 by the resultant force G (G = 2 × F1) of the component F1 in the radial direction R of the vertical drag F that pushes the corresponding driven surface 51 by each cam surface 70. Is done.

Further, since the interposition member 50 is held in the holding recess 80 of the outer peripheral surface 2 c of the steering shaft 2, the position and posture of the interposition member 50 are stabilized. Therefore, the interposition member 50 is stably attached by the pair of cam surfaces 70. I can be strong.
Moreover, as shown to Fig.3 (a), a pair of missing tooth area | region 90 in which the male serration MS is not provided in the both sides of the interposed member 50 regarding the circumferential direction Z of the cylindrical part 20 is provided. Therefore, the tightening force by the tightening bolt 40 is concentrated on the pair of cam surfaces 70, and the steering shaft 2 is opposed to the tubular portion 20 via the interposition member 50 urged by the pair of cam surfaces 70. The portion 23 can be strongly pressed.
(Second Embodiment)
FIG. 6 is a schematic cross-sectional view of a coupling structure PA according to the second embodiment of the present invention. The coupling structure PA in FIG. 6 is mainly different from the coupling structure P in FIG. 5 in the following. That is, as an interposed member, in addition to the interposed member 50, an interposed member 50A disposed on the front end side of the steering shaft 2 with respect to the tightening bolt 40 is added. A holding recess 80 </ b> A is provided on the outer peripheral surface 2 c of the steering shaft 2 and extends from the peripheral groove 2 d toward the front end surface of the steering shaft 2. The holding recess 80A has the same configuration as the holding recess 80 and holds the interposition member 50A.

When assembling the coupling structure PA, after the other end 2b of the steering shaft 2 is inserted into the cylindrical portion 20 of the first yoke 31, first, the interposition member 50A is inserted into the holding recess 80A. Next, after inserting the tightening bolt 40, the interposition member 50 is inserted into the holding recess 80, and then the tightening bolt 40 is tightened.
In the present embodiment, the facing portion 23 can be strongly pressed also at the tip side portion of the other end 2b of the steering shaft 2. For this reason, the fastening force as the whole coupling structure P can be increased. Further, the tilt of the central axis C3 of the steering shaft 2 with respect to the central axis C2 of the cylindrical portion 20 can be suppressed.
(Third embodiment)
FIG. 7 is a schematic view of the periphery of the interposition member of the coupling structure PB according to the second embodiment of the present invention. The coupling structure PB in FIG. 7 is mainly different from the coupling structure P in FIG. That is, the pair of cam surfaces 70B is formed by a part of a common cylindrical surface. The cylindrical surface has a central axis parallel to the central axis C <b> 2 of the cylindrical portion 20 between the slit 21 and the facing portion 23. In addition, the pair of driven surfaces 51B of the interposition member 50B is formed by a part of a cylindrical surface having the same curvature as the pair of cam surfaces 70B.

In the third embodiment, the same effect as that of the first embodiment can be obtained. Although not shown, in the third embodiment, two interposed members may be provided as in the second embodiment.
The present invention is not limited to the above-described embodiments. For example, the holding recess 80 (80A) on the outer peripheral surface 2c of the steering shaft 2 is eliminated, and the pair of cam surfaces 70 (70B) and the outer peripheral surface of the steering shaft 2 are removed. The interposition member 50 (50A) may be disposed in the gap between the 2c. In that case, the pressing surface 52 of the interposition member 50 is not limited to a flat surface as shown in FIG. 3B, and may be convex toward the facing portion 23, or on the contrary, away from the facing portion 23. A concave shape may be formed. In addition, the present invention can be variously modified within the scope of the claims.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle steering device, 2 ... Steering shaft, 2b ... Other end part, 2c ... Outer peripheral surface, 3 ... First universal joint, 4 ... Intermediate shaft, 5 ... Pinion shaft, 6 ... Second universal joint, DESCRIPTION OF SYMBOLS 20 ... Cylindrical part, 21 ... Slit, 22 ... Adjacent part, 23 ... Opposing part, 31 ... 1st yoke, 32 ... 2nd yoke, 33 ... Cross shaft, 40 ... Clamping bolt (clamping shaft), 50; 60B: interposed member, 51; 51B: driven surface, 52: pressing surface, 53 ... regulated surface, 70; 70B ... cam surface, 80; 80, 80A ... holding recess, 90 ... missing tooth region, MS ... Male serration, FS ... Female serration, P: PA; PB ... (Shaft and yoke) coupling structure, X ... Axial direction, Y ... Orthogonal direction, Z ... Circumferential direction

Claims (4)

A shaft having an outer peripheral surface on which male serrations are formed;
A cylindrical portion having an inner peripheral surface formed with a female serration to be engaged with the male serration and fitted to the shaft, the slit extending in the axial direction, and the circumferential direction of the cylindrical portion A universal joint comprising a cylindrical portion having a pair of adjacent portions adjacent to both sides of the slit and an opposing portion facing the slit in the radial direction of the cylindrical portion on the inner peripheral surface of the cylindrical portion. York,
A fastening shaft that crosses the slit in an orthogonal direction orthogonal to the axial direction of the cylindrical portion, and that closes the pair of adjacent portions to each other and fastens the cylindrical portion to the shaft;
A pair of cam surfaces provided in the pair of adjacent portions and inclined inward toward each other as viewed from the axial direction of the cylindrical portion;
An interposed member interposed between the pair of cam surfaces and the outer peripheral surface of the shaft,
The pair of cam surfaces are configured to generate a biasing force that biases the interposition member toward the facing portion when the pair of adjacent portions are brought close to each other. Construction.   The shaft / yoke coupling structure according to claim 1, wherein the interposition member includes a pair of driven surfaces that are in sliding contact with the pair of cam surfaces, respectively.   The shaft / yoke coupling structure according to claim 1, wherein a holding recess for holding the interposition member is formed on an outer peripheral surface of the shaft.   At least one of the inner peripheral surface of the cylindrical part and the outer peripheral surface of the shaft includes a pair of missing tooth regions that are disposed on both sides of the interposition member with respect to the circumferential direction and are not provided with serration teeth. The joint structure of the shaft and yoke as described in any one of 1-3.

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