JP2009299706A - Yoke for universal joint and universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve durability of a yoke 23, by relieving stress acting on a continuous part 31, with a structure that a slit 29 and the continuous part 31 exist in a base part 24 of the yoke 23 of a universal joint. <P>SOLUTION: A recessed part 25 recessed to the outer diameter side is formed in a part being the substantially same phase as the slit 29 in the circumferential direction among an inner peripheral surface of this continuous part 31. Rigidity of this part is reduced more than the other part. Stress acting when further fastening by threadedly engaging a nut with a bolt inserted into a pair of through-holes 28 arranged in the base part 24, and stress acting when transmitting rotation of mutual both rotary shafts respectively fixed to both end parts of the universal joint, are relieved by elastically deforming a part of forming the recessed part 25. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  In the present invention, for example, the ends of a pair of rotating shafts that do not exist on the same straight line, such as a steering shaft and an intermediate shaft of an automobile steering device, are connected to each other, and a rotational force is generated between these rotating shafts. The present invention relates to a universal joint that can transmit the above and a yoke that constitutes the universal joint. In particular, the present invention aims to improve the durability of the universal joint yoke by relieving the stress acting on the base of the universal joint yoke.

  An automobile steering device is configured, for example, as shown in FIG. The movement of the steering wheel 1 is transmitted to the steering gear unit 4 via the steering shaft 2 and the intermediate shaft 3, and the wheels are steered by the steering gear unit 4. In general, the steering shaft 2 and the input shaft 5 of the steering gear unit 4 cannot be provided on the same straight line. For this purpose, conventionally, the intermediate shaft 3 is provided between the steering shaft 2 and the input shaft 5, and both ends of the intermediate shaft 3 and the ends of the steering shaft 2 and the input shaft 5 are connected. They are connected through universal joints 6 and 6 called cardan joints. Thereby, the rotational force can be transmitted between the steering shaft 2 and the input shaft 5 which do not exist on the same straight line.

  As for the universal joint as described above, various structures are known as described in Patent Documents 1 to 5, for example. 18-20 has shown the universal joint 6a described in patent document 1 among these. The universal joint 6 a includes a pair of yokes 7 a and 7 b made of a metal plate and a cross shaft 8. Of the pair of yokes 7a and 7b, one yoke 7a (shown on the right side of FIGS. 18 to 19) is composed of a base 9a and an axial front end edge of the base 9a (the left end of FIGS. 18 to 19). A pair of arms 10 and 10 extending from the edge.

  Of these, the base portion 9a is inserted into an end portion of a rotating shaft (not shown) such as a steering shaft, so that the inner portion can be expanded and contracted by forming a circular cylinder with a discontinuous portion in one circumferential direction. In addition, a pair of flanges 11a and 11b facing each other are provided in the discontinuous portion. A through hole 12 for inserting a flange portion of a bolt (not shown) is formed in one of the flanges 11a. At the same time, a screw hole for screwing the bolt is provided by press-fitting a nut 14 into a through hole 13 formed in the other flange 11b. This screw hole may be directly formed in the flange 11b. The inner peripheral surface of the base portion 9a and the outer peripheral surface of the end portion of the rotating shaft (not shown) are capable of serration engagement with each other.

  Further, the both arm portions 10 and 10 extend in the axial direction of the base portion 9a from two positions opposite to the radial direction at the axial tip portion of the base portion 9a, and face each other inside surfaces. I am letting. Concentric circular holes 15 and 15 are formed at the distal ends of both arms 10 and 10. Further, a corner portion existing in the continuous portion is cut at a continuous portion between the inner side surfaces of both the arm portions 10 and 10 and both end surfaces in the width direction, and an intermediate portion in the longitudinal direction of the both arm portions 10 and 10. The chamfered portions 16 and 16 having a shape as lacked are formed. Each of the chamfered portions 16 and 16 may be formed by plastic working such as press working or forging work, or may be formed by cutting work before or after forming the yoke.

  The other yoke 7b (shown on the left side of FIGS. 18 to 19) of the pair of yokes 7a and 7b is different from the one yoke 7a only in the shape of the base 9b. That is, the base portion 9b that constitutes the other yoke 7b is formed in a substantially cylindrical shape in order to insert the end portion of the rotary shaft 17 such as an intermediate shaft, and the axial tip portion (the right end portion in FIGS. 18 to 19). Part) is bent in the radially outward direction.

  Further, the cross shaft 8 is configured so that both ends of one shaft portion of the two shaft portions constituting the cross shaft 8 and intersecting with the cross are connected to the arm portion 10 of the one yoke 7a. 10 are pivotally supported inside the circular holes 15 and 15 formed in the upper and lower ends of the other shaft 7 and the inner ends of the circular holes 15 and 15 formed in the arm portions 10 and 10 of the other yoke 7b. It is pivotally supported. For this purpose, as shown in FIG. 19, a bearing cup 19 holding a plurality of needles 18 and 18 on the inner peripheral surface of each of the circular holes 15 and 15 so as to roll is press-fitted. At the same time, the end of the cross shaft 8 is inserted inside the needles 18 and 18 in the radial direction.

  When the universal joint 6a configured as described above is used, as shown in FIGS. 18 to 19, the end of the rotary shaft 17 is inserted or press-fitted without rattling inside the base 9b configuring the other yoke 7b. In an (or spline engaged) state, the end of the rotating shaft 17 is welded to the base 9b. At the same time, the flange portion is inserted into the through hole 12 formed in the one flange 11a in a state where the end portion of another rotating shaft (not shown) is engaged with the inside of the base portion 9a constituting the one yoke 7a. The tip of the bolt not shown is screwed into the nut 14 fixed to the other flange 11b and tightened. As a result, the end of the other rotating shaft is coupled and fixed to the base portion 9a based on the fact that the distance between the flanges 11a and 11b is narrowed to reduce the diameter of the base portion 9a. Then, by connecting the ends of the two rotating shafts 17 via the universal joint 6a in this way, the transmission of the rotational force between the rotating shafts 17 that do not exist on the same straight line. To be able to do.

  One yoke 7a constituting the above-described universal joint 6a is formed by, for example, a press work in which a metal plate is punched and bent into a predetermined shape, or is formed by a forging process. FIG. 21 shows the yoke 7c formed by press working. The yoke 7c formed by press working in this way can reduce the manufacturing cost, but is limited to a material that can be easily formed by bending, so that it is difficult to ensure the strength of the yoke 7c.

  On the other hand, when it is formed by forging such as hot forging or cold forging, a strong yoke can be formed. For example, the yoke 7d shown in FIG. 22 is formed by forging. The yoke 7d has a twisted positional relationship between the central axis of the through hole 12 through which the bolt of the base portion 9c is inserted and the central axes of the circular holes 15 and 15 for pivotally supporting the cross shafts of the arm portions 10a and 10a. is there. Therefore, unlike the structure shown in FIGS. 18 to 21 described above, the slit 20 formed at one place in the circumferential direction of the base portion 9c is formed only up to the middle portion of the yoke 7d.

  In the case of such a structure shown in FIG. 22, when a nut is screwed into the tip of a bolt inserted through the through hole 12 of the base 9c and further tightened, the stress in the direction in which the interval between the slits 20 decreases. Works. In this case, stress concentrates on the back end portion of the slit 20 and damage is likely to occur from this portion. In view of such circumstances, in Patent Document 2 out of each of the above-mentioned Patent Documents, as shown in FIG. 23, an enlarged portion 21 is formed in the rear end portion of the slit 20a and the rear end portion is enlarged in an arc shape. The yoke 7e is described. The enlarged portion 21 can relieve stress concentration due to bolt tightening as described above and prevent damage from the rear end portion of the slit 20a.

  The structure shown in FIGS. 22 and 23 is a structure in which the yokes 7d and 7e are formed by forging, and the center axis of the through hole 12 through which the bolt is inserted and the center of the circular holes 15 and 15 that pivotally support the cross shaft. The case where the shaft is in a torsional positional relationship is shown. However, a structure in which the central axis of the through-hole 12 and the central axes of the circular holes 15 and 15 are made parallel can be formed by forging as in the structure shown in FIGS. FIG. 24 shows three examples of such a structure. Of these, FIG. 24A shows the slit 20b formed over the entire axial direction of the base 9d. In FIG. 24B, the slit 20c is formed up to the intermediate portion in the axial direction of the base 9d. Further, FIG. 24C shows an enlarged portion 21 formed at the back end of the slit 20d.

  Of the three examples shown in FIG. 24 described above, in the case of the structure shown in FIG. 24A, the slit 20b is formed over the entire axial direction of the base 9d. There is no inconvenience that stress concentrates on the base end of such a slit. However, since the stress acting on the bolt increases, it is necessary to increase the strength of the bolt. The structures shown in FIGS. 24B and 24C are the same as those shown in FIGS. That is, as shown by the arrows in FIGS. 25A and 25B, the slit 20d having the enlarged portion 21 formed at the rear end portion is more susceptible to the bolt tightening than the slit 20c having the rear end portion not enlarged. , It is difficult for stress to concentrate on the base end, and stress can be relaxed.

  As described above, in the case of a structure in which a slit is provided at the base of the yoke, the stress at the time of bolt tightening can be relieved by providing an enlarged portion at the back end of the slit. However, the yoke is used as a universal joint. The following stress is also applied. That is, when the rotation is transmitted between the rotation axes that do not exist on the same straight line, the arms 10 and 10 of the yoke 7f are axially connected to each other as indicated by arrows in FIGS. Force acts in the direction of displacement. In this case, in the circumferential direction, the tip portion of the base portion 9e (the end portion on the arm portion 10, 10 side, which is the same in the entire specification and claims) is located closer to the arm portion 10, 10 than the slit 20c. A large stress acts on a part of the continuous part 22. And this stress may cause damage to a part of the continuous portion 22. Such stress can be alleviated to some extent by forming an enlarged portion at the base end of the slit as described above, but it may not be sufficient if the torque transmitted by the universal joint increases.

JP-A-10-205547 Japanese Utility Model Publication No. 55-28899 Japanese Utility Model Publication No. 63-164626 Japanese Utility Model Publication No. 6-24235 JP 7-317793 A

  In view of the circumstances as described above, the present invention has a structure in which a slit and a continuous portion are present at the base of the universal joint yoke. The stress acting on the continuous portion is alleviated, and the durability of the universal joint yoke is improved. It was invented to realize a structure that can be improved.

The universal joint yoke and universal joint yoke of the present invention includes a base, a pair of arms, a slit, a continuous portion, a pair of through holes, or a set of through holes and screw holes. With.
Of these, the base is connectable to the end of the rotating shaft.
Further, the both arm portions are plate-like and extend in the axial direction of the base portion from two positions opposite to the radial direction at the axial tip portion of the base portion, and the inner side surfaces thereof are opposed to each other. It is provided in the state. Then, the end of the cross shaft is pivotally supported at each tip.
The slit is provided at one place in the circumferential direction of the base, and the base end in the axial direction of the base is discontinuous in the circumferential direction.
Further, the continuous portion is a portion that is continuous in the circumferential direction, provided at a portion of the distal end portion of the base portion that is axially removed from the slit.
Further, the two through holes or the set of the through holes and the screw holes are aligned with each other at a position deviating from the central axis of the base portion of the portion near the base end of the base portion and sandwiching the slit in the circumferential direction. It is formed at the position to be.
Then, with the rotating shaft inserted into the base, by screwing and tightening a nut to the tip of the bolt inserted through the both through holes, or the tip of the bolt inserted through the through hole is The rotating shaft is fixed to the base by screwing into the screw hole and further tightening.

  In particular, in the universal joint yoke of the present invention, a portion of the continuous portion of the base portion that has substantially the same phase as the slit in the circumferential direction (for example, a portion whose phase shift is within ± 10 degrees). In addition, a low-rigidity portion having lower rigidity than the other portions of the continuous portion is provided.

Specifically, as such a structure, for example, as in the invention described in claim 2, in the inner peripheral surface of the continuous portion of the base portion, in a portion having substantially the same phase as the slit in the circumferential direction. Then, a groove-like recess recessed in the outer diameter side is formed in the axial direction.
Alternatively, as in the invention described in claim 5, the thickness of the continuous portion of the base portion in the portion having substantially the same phase as that of the slit in the circumferential direction is set to be larger than that of other portions of the continuous portion. Provide a smaller part.

When the invention described in claim 2 described above is carried out, preferably, as in the invention described in claim 3, the concave portion is formed by a curved surface curved toward the outer diameter side.
More preferably, as in the invention described in claim 4, the thickness of the portion where the concave portion of the continuous portion is formed is made smaller than the thickness of the other portion of the continuous portion.

  Further, each of the above-mentioned inventions, as in the invention described in claim 6, includes a center axis of a pair of circular holes for pivotally supporting a cross shaft formed at the distal end portion of the pair of arm portions, and a base portion. It can be preferably applied to a structure in which a pair of through-holes or a set of through-holes through which a bolt formed near the proximal end of the screw is inserted and the central axis of the screw hole are parallel.

The universal joint of the present invention includes a pair of universal joint yokes and a cross shaft, as in the seventh aspect of the invention.
Each of the universal joint yokes extends in the axial direction of the base from two base positions that are radially opposite to each other at a base portion that can be coupled to the end portion of the rotating shaft and an axial front end portion of the base portion. A pair of plate-like arm portions for pivotally supporting the end portions of the cross shafts are provided at the respective front end portions provided in a state where the inner side surfaces face each other.
In addition, the cross shaft is configured so that both ends of one shaft portion of the two shaft portions constituting the cross shaft and intersecting the cross are connected to one of the two universal joint yokes. A pair of arm portions constituting the universal joint yoke are pivotally supported at both ends of the other shaft portion, and a pair of arm portions constituting the other universal joint yoke. ing.
In particular, in the universal joint of the present invention, at least one of the two universal joint yokes is the universal joint yoke according to any one of claims 1 to 6.

  In the case of the present invention configured as described above, a concave portion is formed in a portion of the continuous portion that has substantially the same phase as the slit in the circumferential direction (Claim 2), or a thickness is formed in this portion. A low-rigidity portion having low rigidity is provided, for example, by providing a portion (thin-walled portion) with a reduced height (Claim 5). For this reason, the stress which acts on this part can be relieved. For example, when a nut is screwed into a bolt inserted through both through holes and further tightened, stress generated at the back end of the slit is absorbed by the low rigidity portion. Therefore, the stress generated by tightening the bolt can be relaxed. As a result, the durability of the universal joint yoke and the universal joint incorporating the universal joint yoke (claim 7) can be improved.

According to the third aspect of the present invention, since the concave portion is formed by the curved surface, the stress relaxation action can be obtained more remarkably.
According to the invention described in claim 4, in addition to forming the recess, the thickness of the recess is reduced, so that the effect of absorbing the stress in this portion can be increased.

  Furthermore, if each invention mentioned above is applied to the structure described in Claim 6, the stress which acts at the time of the rotation transmission of the rotating shafts which are not on the same straight line will also be relieved. That is, in the case of the structure described in claim 6, since the central axis of both the through holes and the central axis of both the circular holes formed at the distal ends of both arm portions are parallel, the low rigidity portions are It exists in the part between both arms. Accordingly, when rotation is transmitted between the rotating shafts that are not on the same straight line, the stress generated when the force acts in the direction in which these two arm portions are shifted from each other in the axial direction is absorbed and relaxed by the low-rigidity portion.

[First example of embodiment]
1 to 3 show a first example of the embodiment of the present invention. The feature of this example is that a groove-like recess 25 is formed in a part of the base 24 in order to relieve the stress acting on the base 24 constituting the yoke 23. The basic structure and operation of the yoke are the same as those shown in FIG. For this reason, illustration and description of overlapping portions are omitted or simplified, and the following description will be focused on the features of this example.

  The yoke 23 in this example is formed by forging as in the structure shown in FIG. 24 described above, and is formed at the tip of the pair of arm portions 26 and 26 to pivotally support the cross shaft. The central axis of the circular holes 27, 27 and the central axis of the through hole 28 for inserting a bolt formed near the base end of the base portion 24 are parallel to each other. In order to form the through hole 28, a portion near the base end of the base portion 24 is formed in a flange shape, and the through hole 28 is formed in the flange-shaped portion, whereby the bolt inserted into the through hole 28 and the base portion are formed. Interference with the rotating shaft to be inserted into 24 is prevented. In addition, a slit 29 is provided at one portion in the circumferential direction of the base portion 24 so as to make the axial base end portion or intermediate portion of the base portion 24 discontinuous in the circumferential direction at a portion sandwiched between the two through holes 28. Forming. Further, an enlarged portion 30 is formed at the back end portion of the slit 29 by expanding the back end portion into an arc shape. In addition, a portion of the base 24 that is axially disengaged from the slit 29 at the tip portion on the both arm portions 26 and 26 side is a continuous portion 31 that is continuous in the circumferential direction.

  In particular, in the case of this example, the concave portion 25 that is recessed on the outer diameter side in the portion having the same phase as the slit 29 in the circumferential direction on the inner peripheral surface of the continuous portion 31 is axially The continuous portion 31 is formed over the entire length. In addition, the positional relationship in the circumferential direction between the recess 25 and the slit 29 may be such that the slit 29 exists within the circumferential range of the recess 25. Make sure they are in the same phase.

  The concave portion 25 exists in a portion between the through holes 28 formed at the distal ends of the both arm portions 26 and 26. In the case of this example, in order to form the concave portion 25 on the inner peripheral surface of the continuous portion 31, the circumferential direction of the female serration portion 32 formed on the inner peripheral surface of the continuous portion 31 includes the concave portion 25. The predetermined part regarding is missing teeth. In other words, the female serration portion 32 is not continuous in the circumferential direction. The female serration portion 32 engages with a male serration portion formed at the end of the rotation shaft so as to be able to transmit a rotational force.

  Moreover, the said recessed part 25 has a curved surface which curved toward the outer-diameter side, and the circumferential direction both ends are the partial cylindrical surfaces which do not form the said female serration part 32 in the internal peripheral surface of the said continuous part 31 33 and 33 are made continuous smoothly (no corners). In the case of this example, the thickness of the portion of the continuous portion 31 where the concave portion 25 is formed is made smaller than the thickness of the other portion of the base portion 24.

  Further, the concave portion 25 is formed over the entire length of the continuous portion 31 from the opening end surface on the both arm portions 26 and 26 side to the back end portion of the slit 29 in the inner peripheral surface of the continuous portion 31. However, it is determined in terms of design in consideration of actual use conditions, stress distribution due to bolt tightening, and the shape of the yoke 23 itself. For example, when the enlarged portion 30 is formed at the back end portion of the slit 29 as in this example, since the stress at the time of bolt tightening is relieved by the enlarged portion 30, the length of the concave portion 25 is The length in the axial direction of the continuous portion 31 can also be shorter (for example, the length from the opening side end face of the continuous portion 31 to the front side of the rear end of the slit 29). In this case, a female serration portion 32 is formed on a portion of the inner peripheral surface of the continuous portion 31 where the concave portion 25 is not formed, and regarding this portion, the female serration portion 32 is missing over the entire circumference. Not all teeth are good. Further, the depth of the concave portion 25 is determined by design in the same manner as the length in the axial direction.

  Further, the method for forming the yoke 23 as described above may be cold forging or hot forging. In the case of hot forging, since the surface of the forging material is rough and the dimensional accuracy is low, machining such as cutting after forging increases, and the manufacturing cost increases. However, the material strength can be increased by refining carbon steel such as S35C and S45C. Further, since the degree of freedom of the shape is high, it can be processed even if the shape is somewhat complicated. On the other hand, in the case of cold forging, since the dimensional accuracy can be increased, machining after forging can be reduced and the manufacturing cost can be reduced. However, since the life of the mold is short, depending on the number set for mass production, the cost of the mold becomes high and the manufacturing cost may increase. Moreover, in order to ensure moldability, low carbon steel having a relatively low material strength is used. However, depending on the processing rate, the strength is improved by work hardening. For this reason, the method for forming the yoke 23 is determined in terms of design in consideration of the balance between the number of mass production and the cost. In any case, the recess 25 is preferably formed at the time of forging, but may be formed by machining when forging after forging.

  In the case of this example configured as described above, a portion of the continuous portion 31 that has substantially the same phase as the slit 29 in the circumferential direction (for example, a range of ± 10 degrees, or at least a portion of the slit 29 and a recess Since the concave portion 25 is formed in a range in which at least a part of 25 overlaps in the axial direction, the stress acting on this portion can be relieved. In other words, in the case of this example, by forming the concave portion 25, the rigidity of the portion of the continuous portion 31 that has substantially the same phase as the slit 29 is made lower than the other portions. In the case of this example, the central axis of the two through holes 28 and the central axes of the circular holes 27 and 27 formed at the distal end portions of the arm portions 26 and 26 are parallel to each other. The slit 29 exists in a portion between the both through holes 28 and a portion between the both arm portions 26 and 26. For this reason, as shown in FIG. 3, when a nut (not shown) is screwed into the bolt 34 inserted through the two through holes 28 and further tightened, the stress generated at the base end of the slit 29 is Absorbed by the recess 25.

  Specifically, as the bolt 34 is tightened, a compressive stress acts on the continuous portion 31 in the direction in which the interval between the slits 29 becomes narrower as shown by the arrow in FIG. In the case of this example, even if a compressive stress acts in this way, the portion of the continuous portion 31 where the concave portion 25 is formed bends in a direction in which the radius of curvature of the concave portion 25 decreases, thereby absorbing this stress. To do. As a result, as shown in FIG. 4A, the stress distribution becomes substantially constant (substantially averaged), and the yoke 23 is hardly damaged. On the other hand, in the structure in which the concave portion 25 is not formed, the stress distribution is locally increased as shown in FIG. 4B, and breakage easily occurs from this portion.

  Further, in the case of this example, as shown in FIG. 24 described above, when transmitting the rotation between the rotating shafts that are not on the same straight line, the force is applied in the direction in which both the arm portions 26 and 26 of the yoke 23 are shifted in the axial direction. The stress generated when it acts is also absorbed and relaxed by the portion where the recess 25 is formed. That is, when a force is applied in a direction in which both the arm portions 26 and 26 are displaced in the axial direction, as shown in FIG. 5A, the portion where the concave portion 25 is formed is shown in (a) → (b). It deforms like twisting. That is, at the time of transmission of rotation between the two rotating shafts, both side portions sandwiching the concave portion 25 in the circumferential direction of the continuous portion 31 are relatively displaced in directions opposite to each other in the axial direction. In the case of this example, the portion where the concave portion 25 is formed has low rigidity and is easily elastically deformed, so that such a relative displacement can be greatly allowed. Therefore, as shown in FIGS. 5A and 5B, the portion formed with the recess 25 is elastically deformed in the direction in which the radius of curvature of the recess 25 increases, thereby relieving the stress caused by the relative displacement. The

  On the other hand, in the case of the structure in which the concave portion 25 is not formed, as shown in FIG. 5B, a part of the continuous portion 31 is (a) → (b) during the rotation transmission between the two rotating shafts. Deforms as shown in In this case, the rigidity of the portion of the continuous portion 31 where the stress is applied due to such deformation is hardly different from the other portions, so that it is difficult to absorb this stress. For this reason, this stress concentrates on a part and it becomes easy to produce a damage from the part where this stress concentrated.

  As shown in FIG. 6, it is conceivable to form the recess 25 on the opposite side of the slit 29 in the circumferential direction of the continuous portion 31. In the case of this structure, the portion where the recess 25 is formed is on the opposite side of the portion having the same phase as the slit 29 where the stress is most concentrated as described above. I can't relax. On the other hand, in this example, since the concave portion 25 is formed in a portion of the continuous portion 31 where stress is most likely to concentrate, such stress can be sufficiently relaxed.

  In the case of this example, since the concave portion 25 is formed by a curved surface, the stress relaxation action can be obtained more remarkably. That is, when a corner exists in the recess 25, stress concentrates on the corner. Therefore, even if the portion where the concave portion 25 is formed is elastically deformed as described above, there is a possibility that the stress relaxation action cannot be sufficiently obtained. On the other hand, if the concave portion 25 is formed of a curved surface as in this example, stress concentration can be prevented and the above-described stress relaxation action can be sufficiently obtained. In the case of this example, since the thickness of the portion where the concave portion 25 is formed is reduced, the portion where the concave portion 25 is formed is more easily elastically deformed, and the stress can be more easily absorbed.

  As described above, in the case of this example, both the stress acting when tightening the bolt 34 and the stress acting when transmitting the rotation between the two rotating shafts can be alleviated as compared with the structure in which the recess 25 is not formed. . Therefore, the durability of the universal joint yoke 23 and a universal joint 35 incorporating the yoke 23 as shown in FIG. 14 described later can be improved.

[Second and third examples of embodiment]
7 and 8 respectively show second and third examples of the embodiment of the present invention. In the case of these second and third examples, the center of curvature of the recess 25 a exists on the outer diameter side of the portion (basic circle) where the female serration portion 32 is formed on the inner peripheral surface of the continuous portion 31. And the curvature of the said recessed part 25a is enlarged (a curvature radius is made small).
Further, in the case of the second example shown in FIG. 7, partial cylindrical surfaces 33 and 33 are formed in a portion between the female serration portion 32 and the recess 25a in the circumferential direction, and the female serration portion 32 is missing. .
On the other hand, in the case of the third example shown in FIG. 8, the female serration portion 32 is formed up to the edge of the recess 25a without providing such partial cylindrical surfaces 33 and 33. In any structure, it is preferable that the both side edges of the recess 25a and the portions existing on both sides in the circumferential direction of the recess 25a are smoothly continuous by curved portions having an arcuate cross section.
Other structures and operations are the same as those in the first example.

[Fourth and fifth examples of embodiment]
9 to 11 show fourth and fifth examples of the embodiment of the present invention, respectively. In the case of these fourth and fifth examples, unlike the structures of the second and third examples described above, the center of curvature of the recess 25b is the inner diameter of the portion (basic circle) where the female serration portion 32 is formed on the inner peripheral surface of the continuous portion 31. Exists on the side. And the curvature of the said recessed part 25b is made small.
In the case of the fourth example shown in FIGS. 9 to 10, the recess 25 b is formed with the slit 29 in the circumferential direction of the continuous part 31 in the same manner as the structures of the first example and the second and third examples. It is formed in a portion having substantially the same phase.
On the other hand, in the case of the fifth example shown in FIG. 11, the concave portions 25 b and 25 b are formed on the opposite side of the slit 29 in addition to the portion having the same phase as the slit 29 in the circumferential direction. Yes.
Other structures and operations are the same as those in the first example.

[Sixth and Seventh Embodiments]
12 and 13 respectively show sixth and seventh examples of the embodiment of the present invention. In the case of these sixth and seventh examples, the outer peripheral surfaces of the base portions 24 and 24a are brought closer to the peripheral portion of the enlarged portion 30 to thicken this portion. In the case of the sixth and seventh examples, since the peripheral portion of the enlarged portion 30 is thickened, the stress acting on the periphery of the enlarged portion 30 during bolt tightening can be further relaxed, and the yokes 23, 23a The durability of the can be further improved. The structure of the seventh example shown in FIG. 13 is the same as the conventional structure shown in FIGS. 22 to 23 described above, and the circular hole 27 that pivotally supports the central axis of the through hole 28a through which the bolt is inserted and the cross shaft. , 27 and the central axis are in a twisted positional relationship.
Other structures and operations are the same as those in the first example with respect to the sixth example shown in FIG. Further, the seventh example shown in FIG. 13 is the same as the conventional structure shown in FIG. In the case of the structure of the seventh example as described above, a recess similar to that of the first example is formed in the vicinity of the connecting portion with the upper arm portion 26a in FIG. 13 on the inner peripheral surface of the continuous portion 31a of the base portion 24a. Is forming.

[Eighth Example of Embodiment]
14 to 15 show an eighth example of the embodiment of the present invention. In the case of this example, the yoke 23b is a press yoke formed by pressing a metal plate into a predetermined shape and bending it. And the bridge member 36 is spanned over the part which is not continuous regarding the circumferential direction of the base 24b. That is, in this example, the base 24b is not continuous in the circumferential direction except for the bridge member 36. Accordingly, the portion of the base 24b where the bridge member 36 is provided is discontinuous with respect to the circumferential direction, which is present on both sides in the axial direction of the bridge member 36 in a part of the continuous portion described in the claims. These parts correspond to the slits, respectively. In the case of this example, the circumferentially central portion of the bridge member 36 is curved radially outward to form a recess 25c on the inner peripheral surface of this portion. Note that the bridge member 36 is coupled at both ends to the base 24b by, for example, fitting into a notch formed in a predetermined portion of the base 24b, or by welding.

  In the case of the illustrated example, the entire central portion in the circumferential direction of the bridge member 36 is curved outward in the radial direction of the base portion 24b to form the concave portion 25c. Therefore, the portion where the concave portion 25c is formed. The wall thickness (the radial dimension of the base portion 24b) is not particularly reduced. This is to ensure the strength of the bridge member 36 while allowing a certain degree of elastic deformation when a force is applied to the bridge member 36 in the compression direction or torsional direction. If the strength of the bridge member 36 in the axial direction of the base 24b can be increased by other methods such as increasing the thickness of the base 24b, the thickness of the portion where the recess 25c is formed in the radial direction of the base 24b. It may be small.

In the case of this example as described above, since the concave portion 25c is formed in the central portion of the bridge member 36 in the circumferential direction, the rigidity of the central portion of the bridge member 36 is lower than the other portions of the bridge member 36. . That is, when a stress in the compressing direction is applied at the time of bolt tightening, the concave portion 25c bends in a direction in which the radius of curvature becomes small, and this stress is relaxed. On the other hand, when stress in the torsional direction is applied during the rotation transmission between the two rotation shafts, the portion of the bridge member 36 where the recess 25c is formed is similar to the case shown in FIG. The concave portion 25c is elastically deformed in the direction in which the radius of curvature increases, and this stress is relieved. In the case of this example, since the bridge member 36 is provided, a part of the stress acting when the bolt is tightened is supported by the bridge member 36. For this reason, the stress which acts on this bolt can be reduced.
Other structures and operations are the same as those in the first example.

  The present invention is not limited to the structure of each of the above-described embodiments. For example, as shown in FIG. 16, each of the universal joints including yokes 37a and 37a fixed to both ends of the intermediate shaft 3 of the steering device by welding. The present invention can be applied to universal joint yokes and universal joints that satisfy the requirements described in the claims. For example, in the case of the structure shown in FIG. 16, the yokes 37b and 37b connected to the yokes 37a and 37a via the cross shaft 8 are configured as described in the above embodiments.

  In each of the above-described embodiments, the rigidity is lowered by forming the concave portion in the continuous portion. However, without forming the concave portion, the phase is substantially the same as that of the slit in the circumferential direction of the continuous portion. Even by reducing the thickness of the portion, the rigidity as described above can be reduced to relieve the stress as described above. For example, the wall thickness is gradually reduced from the both sides in the circumferential direction toward the central portion in the circumferential direction.

The perspective view of the yoke for universal joints which shows the 1st example of embodiment of this invention. Similarly, the figure seen from a pair of arm part side regarding an axial direction. The figure seen from the same direction as FIG. 2 in the state which inserted the volt | bolt in one pair of through-holes. (A) is a schematic diagram showing the distribution of stress acting on the portion where the concave portion of the continuous portion is formed, and (B) is a schematic diagram showing the stress portion when the concave portion is not formed on the continuous portion. (A) shows the case where there is a concave portion in the continuous part, (B) shows the case where there is no concave part in the continuous part, and (a) shows the state before the stress acts. Is a schematic diagram showing the state in which stress is applied. The figure similar to FIG. 2 which shows the structure which formed the recessed part on the opposite side to the slit regarding the circumferential direction. The figure similar to FIG. 2 which shows the 2nd example of embodiment of this invention. The figure similar to FIG. 2 which shows the 3rd example. The figure similar to FIG. 2 which shows the 4th example. FIG. The figure similar to FIG. 2 which shows the 5th example of embodiment of this invention. The perspective view of the universal joint yoke which shows the 6th example. The perspective view of the yoke for universal joints which shows the 7th example. The perspective view of the yoke for universal joints which shows the 8th example. Similarly, the figure seen from the base side regarding the axial direction. The partially cutaway side view which shows the universal joint which can apply this invention in the state assembled | attached to the both ends of the intermediate shaft. The side view which cuts and shows one example of the steering apparatus for motor vehicles provided with the universal joint used as the object of this invention. The side view which shows an example of the conventional structure of a universal joint. The figure seen from the lower part of FIG. 18 shown in the state which cut | disconnected a part. FIG. 19 is a cutaway view of FIG. The perspective view which shows one example of a press yoke. The perspective view which shows an example of the yoke formed by the forge process. The top view which shows one example of the conventional structure which formed the enlarged part in the back end part of the slit. The top view which shows three examples of the structure where the central axis of the circular hole formed in both the arm parts and the central axis of the through-hole formed in the base part are parallel. The schematic diagram which shows the action state of the stress when the enlarged part is not formed in the base end part of a slit, and when it forms (B). The schematic diagram which exaggerates and shows the force which acts on a yoke at the time of the rotation transmission of the rotating shafts which are not on the same straight line.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering shaft 3 Intermediate shaft 4 Steering gear unit 5 Input shaft 6, 6a Universal joint 7a, 7b, 7c, 7d, 7e, 7f Yoke 8 Cross shaft 9a, 9b, 9c, 9d, 9e Base 10, 10a Arm Part 11a, 11b Flange 12 Through-hole 13 Through-hole 14 Nut 15 Circular hole 16 Chamfered part 17 Rotating shaft 18 Needle 19 Bearing cup 20, 20a, 20b, 20c, 20d Slit 21 Enlarged part 22 Continuous part 23, 23a, 23b Yoke 24 24a, 24b Base part 25, 25a, 25b, 25c Recess 26, 26a Arm part 27 Circular hole 28, 28a Through hole 29 Slit 30 Enlarged part 31, 31a Continuous part 32 Female serration part 33 Partial cylindrical surface 34 Bolt 35 Universal joint 36 Bridge members 37a, 37 Yoke

Claims (7)

  In a state in which the base portion that can be coupled to the end portion of the rotating shaft and the axially distal end portion of the base portion extend in the axial direction of the base portion from two positions opposite to the radial direction and the inner side surfaces thereof face each other. A pair of plate-like arm portions for pivotally supporting the end portions of the cross shaft at the respective distal end portions, and one base portion in the circumferential direction of the base portion. A slit that is discontinuous in the circumferential direction, a continuous portion that is provided in a portion that is axially deviated from the slit at the distal end portion of the base portion, and a portion near the proximal end of the base portion. Of these, a pair of through holes or a pair of through holes and screw holes formed at positions deviating from the central axis of the base and aligned with each other across the slit in the circumferential direction, With the rotating shaft inserted into the base, a bolt inserted through both the through holes. A universal joint that fixes the rotating shaft to the base by screwing and tightening a nut to the tip of the screw, or by screwing and tightening the tip of a bolt inserted through the through hole into the screw hole. In the yoke for use, in the portion of the continuous portion of the base portion, a portion having a phase substantially the same as that of the slit in the circumferential direction is provided with a low-rigidity portion having lower rigidity than the other portions of the continuous portion. Characteristic universal joint yoke.   The universal joint according to claim 1, wherein a groove-like concave portion recessed in the outer diameter side is formed in an axial direction in a portion of the inner peripheral surface of the continuous portion of the base portion that has substantially the same phase as the slit in the circumferential direction. For yoke.   The universal joint yoke according to claim 2, wherein the concave portion is formed by a curved surface curved toward the outer diameter side.   The universal joint yoke according to claim 2 or 3, wherein a thickness of a portion where the concave portion of the continuous portion is formed is smaller than a thickness of other portions of the continuous portion.   The universal joint yoke according to claim 1, wherein a portion having a smaller thickness than other portions of the continuous portion is provided in a portion of the continuous portion of the base that is substantially in phase with the slit in the circumferential direction.   A pair of through-holes through which a central axis of a pair of circular holes for pivotally supporting the cross shaft formed at the distal ends of the pair of arms and a bolt formed near the base end of the base are inserted or The universal joint yoke according to any one of claims 1 to 5, wherein the pair of through holes and the central axis of the screw hole are parallel to each other. A pair of universal joint yokes and a cross shaft;
Each of the universal joint yokes extends in the axial direction of the base from two base positions that are radially opposite to each other at a base portion that can be coupled to the end portion of the rotating shaft and an axial front end portion of the base portion. Provided with a pair of plate-like arm portions for pivotally supporting the ends of the cross shafts at the respective tip portions provided in a state where the inner side surfaces thereof are opposed to each other;
The cross shaft is composed of both ends of one of the two shaft portions provided in a crossing manner that constitute the cross shaft, and one universal joint of the universal joint yokes. Similarly, both end portions of the other shaft portion are pivotally supported by the tip portions of the pair of arm portions constituting the yoke for use, and the tip portions of the pair of arm portions constituting the other universal joint yoke, respectively. In universal joints,
A universal joint, wherein at least one of the universal joint yokes is the universal joint yoke according to any one of claims 1 to 6.

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