JP2014077493A - Fastening structure of shaft and yoke - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fastening structure of a shaft and a yoke which can save a substantial zone of contact of both serration widely.SOLUTION: A yoke 5 contains a tubular unit 10 forming a slit 11 extending axially, and fitting in a shaft. An internal circumference 10a of the tubular unit 10 contains a female serration formation area 30. A clamping axis crossing in the slit tightens the tubular unit 10 to the shaft. The female serration formation area 30 contains a first area 41, and second areas 51 and 52 arranged nearer the slit 11 than the first area 41. A female serration 18A of the first area 41 has a basic tooth profile shape. Female serrations 18B of the second areas 51 and 52 each have an offset tooth profile shape formed by offsetting the basic tooth profile shape at non-fastening to a direction leaving from a center axis C1 of the tubular unit 10.

Description

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

  In a vehicle steering apparatus, shafts that transmit an operation force of a steering member are connected to each other by a cross shaft type universal joint. As a fastening structure between the yoke and shaft of the cruciform universal joint, a bolt is used to tighten the cylindrical portion with slits of the yoke to reduce the diameter, and the shaft is serrated to the cylindrical portion and fastened. And a yoke fastening structure have been proposed (see, for example, Patent Document 1).

JP 2009-299706 A

  In the cylindrical portion, the closer to the slit, the larger the deformation amount due to bolt tightening, and the farther from the slit, the smaller the deformation amount due to bolt tightening. For this reason, when tightening with bolts, the female serration is in local contact (tooth contact) with the male serration only in a part of the circumferential direction of the cylindrical portion, and the substantial contact area between the two serrations Becomes narrower. Therefore, when receiving rotational torque by steering, play due to relative displacement occurs between the male and female serrations, which may reduce the steering feeling.

  Therefore, an object of the present invention is to provide a shaft and yoke fastening structure that can ensure a substantial contact area between both serrations.

  In order to achieve the object, the invention of claim 1 is characterized in that a shaft (2) having an outer periphery (2b) formed with a male serration (8) and a female serration (18A, 18B) meshing with the male serration are formed. A yoke (10) having an inner periphery (10a) including a female serration formation region (30), and having a slit (11) extending in the axial direction (X1) and including a tubular portion (10) fitted to the shaft ( 5) and a fastening shaft (16) that crosses the slit and fastens the cylindrical portion to the shaft, and the female serration formation region is more than the first region (41) and the first region. A second region (51, 52) disposed in proximity to the slit, wherein the female serration of the first region has a reference tooth profile, and the female serration of the second region is not fastened. Above Forms an offset tooth profile formed by an offset in a direction away quasi tooth profile from the cylindrical portion of the center axis (C1), to provide a fastening structure of the shaft and the yoke (1).

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.
Further, as in claim 2, the female serration of the second region at the time of non-fastening may be increased in offset amount from the central axis of the cylindrical portion as it approaches the slit.

According to a third aspect of the present invention, the offset tooth profile at the time of non-fastening is obtained by setting the reference tooth profile to a predetermined angle around the position of the tooth tip of the female serration farthest from the slit in the female serration in the second region. The shape may be a rotationally displaced shape.
According to a fourth aspect of the present invention, the predetermined angle may be in an angle range of 0.3 to 0.7 degrees.

  According to invention of Claim 1, there exist the following effects. That is, if the gap between the male and female serrations is constant over the entire circumference of the cylindrical portion when not fastened, the tooth is first moved in the region near the slit with a large deformation amount when transitioning from non-fastened to fastened. Hit. For this reason, the number of teeth of male and female serrations that simultaneously contact teeth decreases. On the other hand, in the present invention, the female serration in the second region that is close to the slit and easily deforms when tightened is offset in a direction away from the central axis of the cylindrical portion when not fastened. Therefore, when shifting from the non-fastened state to the fastened state, the female serration of the second region and the remaining female serrations of the first region can be simultaneously brought into contact with the male serration. As a result, it is possible to increase the number of teeth of both serrations that simultaneously contact the teeth. Thereby, since the substantial contact area of both serrations can be increased, generation | occurrence | production of backlash etc. can be suppressed and a steering feeling can be improved.

  Further, according to the invention of claim 2, the following effects can be obtained. That is, in the second region, the closer to the slit, the larger the deformation amount at the time of fastening. On the other hand, in the present invention, since the female serration in the second region is increased in the offset amount as it approaches the slit, the number of teeth of the two serrations that simultaneously contact the teeth at the time of tightening is reliably increased. Can do. Thereby, the substantial contact area of both serrations can be increased reliably, and the steering feeling can be reliably improved through play back suppression.

  According to the invention of claim 3, the offset tooth profile shape of the female serration of the second region when not fastened is centered on the position (P1) of the tooth tip of the female serration farthest from the slit in the female serration of the second region. As described above, the reference tooth profile shape was rotated and displaced by a predetermined angle. Therefore, since the tooth profile shape of the female serration in the second region can be offset in the direction opposite to the direction of deformation of the second region when shifting from the non-fastened state to the fastened state, The number of teeth can be reliably increased. Thereby, the substantial contact area of both serrations can be increased reliably, and the steering feeling can be reliably improved through play back suppression.

  According to the invention of claim 4, by setting the predetermined angle in the range of 0.3 to 0.7 degrees, it is possible to reliably increase the number of teeth of both serrations that simultaneously contact the teeth during tightening. it can.

It is a schematic side view of the fastening structure of the shaft and yoke of one Embodiment of this invention. It is a schematic sectional drawing of the fastening structure of FIG. 1, and has shown the non-fastened state before fastening with a fastening bolt. It is sectional drawing of the cylindrical part of the yoke of the universal joint which is an element of the fastening structure of FIG. 1, and has shown the non-fastened state.

A preferred embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic side view of a shaft coupling structure 1 according to an embodiment of the present invention. In the shaft coupling structure 1, when a pair of shafts 2 and 3 that transmit a steering force of a steering device are connected via a universal joint 4, any one of the shafts (for example, the shaft 2) and the corresponding yoke of the universal joint 4. (For example, the first yoke 5).

  Although not shown, the pair of shafts 2 and 3 may be a lower shaft and an intermediate shaft of the steering shaft. The pair of shafts 2 and 3 may be an intermediate shaft and a pinion shaft. The pair of shafts 2 and 3 may be an intermediate shaft and an extension shaft.

  As shown in FIG. 1, the universal joint 4 includes a first yoke 5 to which the end 2 a of the shaft 2 is connected, a second yoke 6 to which the end 3 a of the shaft 3 is connected, a first yoke 5, A cross shaft 7 for connecting the two yokes 6 is provided. A male serration 8 is formed on the outer periphery 2 b of the end 2 a of the shaft 2. A circumferential groove 9 that crosses the male serration 8 is formed on the outer periphery 2 b of the end 2 a of the shaft 2.

  Referring to FIG. 2, which is a schematic sectional view of the fastening structure 1 in FIG. 1, the first yoke 5 has a cylindrical portion 10 to which the end 2 a of the shaft 2 is fitted. The tubular portion 10 has a slit extending along the radial direction R1 of the tubular portion 10 and extending in the axial direction of the tubular portion 10 (a direction orthogonal to the paper surface in FIG. 2; a direction coinciding with the axial direction X1 of the shaft 2). 11 is provided. The first yoke 5 has a pair of tabs 12 and 13 on both sides of the slit 11.

Fastening bolts 16 as fastening shafts are inserted into bolt insertion holes 14 and 15 provided in the respective tabs 12 and 13. The pair of tabs 12 and 13 are tightened between the nut 17 engaged with the tip of the tightening bolt 16 and the head portion 16a of the tightening bolt 16, whereby the cylindrical portion 10 is reduced in diameter. An end 2 a of the shaft 2 is fastened in the cylindrical portion 10.
Female serrations 18 </ b> A and 18 </ b> B for meshing with the male serration 8 of the shaft 2 are formed on the inner periphery 10 a of the cylindrical portion 10. FIG. 2 shows a non-fastened state before the tightening bolt 16 is tightened, and a gap is provided between the female serrations 18 </ b> A and 18 </ b> B and the male serration 8.

  FIG. 3 shows a cross section of the cylindrical portion 10 when not fastened (no load state). As shown in FIG. 3, the inner periphery 10 a of the cylindrical portion 10 includes a pair of toothless regions 21 and 22 as a pair of female serration non-forming regions disposed on both sides adjacent to the slit 11 and sandwiching the slit 11. And the female serration forming region 30 provided in the entire region other than the missing tooth regions 21 and 22.

The female serration forming region 30 includes a first region 41 and a pair of second regions 51 and 52 disposed closer to the slit 11 than the first region 41. The second region 51 is close to the slit 11 with the missing tooth region 21 interposed therebetween. The second region 52 is close to the slit 11 with the missing tooth region 22 interposed therebetween.
The female serration 18A of the first region 41 has a reference tooth shape. The female serrations 18 </ b> B of the second regions 51 and 52 have an offset tooth profile formed by offsetting the reference tooth profile in a direction away from the central axis C <b> 1 of the cylindrical portion 10 when not fastened.

Specifically, in the female serrations 18 </ b> B of the second regions 51 and 52 when not fastened, the offset amount from the central axis C <b> 1 of the cylindrical portion 10 is increased as the female serration 18 </ b> B approaches the slit 11.
That is, the offset tooth profile of each of the second regions 51 and 52 when not fastened is centered on the tooth tip position P1 of the female serration 18B1 farthest from the slit 11 in the female serration 18B of the second region 51, 52. This is a shape in which the tooth profile is rotationally displaced by a predetermined angle θ1. The predetermined angle θ1 is set to an angle range of 0.3 to 0.7 degrees.

According to this embodiment, the following effects are produced. That is, if the gap between the male and female serrations is constant over the entire circumference of the cylindrical portion when not fastened, the tooth is first moved in the region near the slit with a large deformation amount when transitioning from non-fastened to fastened. Hit. For this reason, the number of teeth of male and female serrations that simultaneously contact teeth decreases.
On the other hand, in this embodiment, the female serrations 18B of the second regions 51 and 52 that are close to the slit 11 and easily deformed when tightened are offset in a direction away from the central axis C1 of the tubular portion 10 when not fastened. The gap between the female serration 18B and the corresponding male serration 8 is made larger than the gap between the female serration 18A in the first region 41 and the corresponding male serration 8.

  Therefore, the female serration 18B in the second regions 51 and 52 and the female serration 18A in the remaining first region 41 can be simultaneously brought into contact with the male serration 8 when shifting from the non-fastened time to the fastened time. As a result, it is possible to increase the number of teeth of both serrations 8; Thereby, since the substantial contact area of both the serrations 8; 18A and 18B can be increased, it is possible to suppress the occurrence of play and the like and improve the steering feeling.

In other words, at the time of fastening, it is possible to absorb the bias of deformation of the tubular portion 10 due to the fastening of the fastening bolts 16 and make the pitch circle of the entire female serrations 18A and 18B of the tubular portion 10 close to a perfect circle. Therefore, it is possible to realize equal tooth contact of both serrations 8; 18A and 18B.
Moreover, in each 2nd area | region 51 and 52, the deformation amount at the time of fastening is so large that it is near the slit 11. On the other hand, in the present embodiment, the female serrations 18B of the second regions 51 and 52 have their offset amounts increased as they approach the slits 11, so that the two serrations 8 that simultaneously contact each other during tightening; The number of teeth of 18A and 18B can be increased reliably. Thereby, the substantial contact area of both the serrations 8; 18A, 18B can be reliably increased, and the steering feeling can be reliably improved through the play back suppression.

  Further, the offset tooth profile shape of the female serration 18B of each of the second regions 51 and 52 at the time of non-fastening is defined as the tooth tip position P1 of the female serration 18B1 farthest from the slit 11 in the female serration 18B of the second regions 51 and 52. As a center, a reference tooth profile shape was rotationally displaced by a predetermined angle. Therefore, the tooth profile shape of the female serration 18B of each of the second regions 51 and 52 can be offset in a direction opposite to the direction of deformation of each of the second regions 51 and 52 when shifting from non-fastening to fastening. It is possible to reliably increase the number of teeth of both serrations 8; Thereby, the substantial contact area of both the serration serrations 8; 18A and 18B can be reliably increased, and the steering feeling can be reliably improved through the play back suppression.

  Further, by setting the predetermined angle θ1 to an angle range of 0.3 to 0.7 degrees, it is possible to reliably increase the number of teeth of both serrations 8; That is, when the predetermined angle θ1 is smaller than 0.3 degrees, the effect of equalizing the tooth contact over the entire circumference of the tubular portion 10 during fastening is reduced. On the other hand, when the predetermined angle θ1 is larger than 0.7 degrees, the tightening torque for making the tooth contact uniform over the entire circumference of the cylindrical portion 10 at the time of fastening becomes too large. Therefore, by setting the predetermined angle θ1 to an angle range of 0.3 to 0.7 degrees (0.3 degrees or more and 0.7 degrees or less), the tooth contact on the entire circumference is made uniform with an appropriate tightening torque. be able to. From such a viewpoint, the predetermined angle θ1 is more preferably set to an angle range of 0.4 to 0.6 degrees, and the predetermined angle θ1 is further preferably set to 0.5 degrees.

The present invention is not limited to the above-described embodiment. For example, the missing tooth regions 21 and 22 may be narrower, or the missing tooth regions 21 and 22 may be eliminated. When the missing tooth regions 21 and 22 are abolished, the second regions 51 and 52 are adjacent to the slit 11.
When processing the female serrations 18B in the second regions 51 and 52, a displacement equivalent to the displacement amount at the time of fastening with the fastening bolt 16 is applied in advance to the intermediate for manufacturing the cylindrical portion of the yoke. You may make it process the female serration of the reference tooth profile shape arrange | positioned at a perfect circle in the inner periphery of the intermediate body for manufacture of a cylindrical part in the restrained state. When the displacement of the cylindrical portion 10 is released after the processing, the female serration in the region close to the slit 11 spreads outward by the spring back, and the female serration 18B of the second regions 51 and 52 can be easily formed, and the remaining The region becomes the first region 41.

In the embodiment, the offset tooth profile of each of the second regions 51 and 52 is formed by being rotationally displaced about the tooth tip position P1, but is formed by being rotationally displaced about the position of the tooth bottom. May be.
In addition, various modifications can be made within the scope of the claims of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Fastening structure of a shaft and a yoke, 2, 3 ... Shaft, 2b ... Outer periphery, 4 ... Universal joint, 5 ... 1st yoke, 6 ... 2nd yoke, 7 ... Cross shaft, 8 ... Male serration, 10 ... Cylindrical shape Part, 10a ... inner circumference, 11 ... slit, 12, 13 ... tab, 16 ... clamping bolt (clamping shaft), 18A, 18B ... female serration, 21, 22 ... female serration non-formation region, 30 ... female serration formation Area 41 ... 1st area 51, 52 ... 2nd area, C1 ... Central axis (of the cylindrical part), P1 ... Position of tooth tip, θ1 ... Predetermined angle, X1 ... Axial direction

Claims (4)

A shaft having an outer periphery formed with male serrations;
A yoke including an inner periphery including a female serration forming region in which a female serration meshing with the male serration is formed, and including a cylindrical portion fitted in the shaft by forming a slit extending in an axial direction;
A fastening shaft that intersects the slit and fastens the cylindrical portion to the shaft, and
The female serration forming region includes a first region and a second region disposed closer to the slit than the first region,
The female serration of the first region has a reference tooth profile shape,
The female serration in the second region has an offset tooth profile formed by offsetting the reference tooth profile in a direction away from the central axis of the cylindrical portion when not fastened.   The shaft-yoke fastening structure according to claim 1, wherein the female serration in the second region when not fastened has a larger offset amount from the central axis of the cylindrical portion as it approaches the slit.   3. The offset tooth profile when not fastened according to claim 2, wherein the reference tooth profile is rotationally displaced by a predetermined angle around the position of the tooth tip of the female serration farthest from the slit in the female serration of the second region. Fastening structure of shaft and yoke.   The shaft and yoke fastening structure according to claim 3, wherein the predetermined angle is in an angle range of 0.3 to 0.7 degrees.

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