JP2005023959A - Power transmission, and ball interconnecting structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent stress concentration caused by projection of a contact ellipse when transmitting the power in a power transmission of a type with an engagement head part and a fitting member press-fitted therein. <P>SOLUTION: A fitting recessed surface 26 of a fitting member 24 has an angular contact shape so as to be brought into contact with two contact parts PC1 and PC2 located on both sides of a center point S of an engagement head part 20 in the fitting direction parallel to the center line L of a fitting member 24. A pair of run outs 40a and 40b are formed in the engagement head part 20 at a part corresponding to the contact part PC2 on the fitting tip side of the fitting member 24, and located in the force transmitting direction so as not to be brought into contact with the contact part PC2 when the force is transmitted. The contact ellipse 36 is not projected from the fitting member 24 as shown in (b), and wear in an early stage or damages caused by stress concentration can be avoided thereby. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power transmission device, and more particularly to an improvement of a power transmission device that transmits torque through a spherical contact such as a tripod joint.
[0002]
[Prior art]
(A) three or more ball members provided in a radial direction at three or more locations around the rotation center line of the first rotating member, each having a spherical engaging head at the tip;
(B) Three or more second rotation members provided substantially concentrically with the first rotation member are disposed corresponding to the three or more ball members, and can be relatively rotated with respect to the engagement head. A fitting member having a fitting concave surface to be fitted, and (c) allowing the first rotating member and the second rotating member to swing, and the engaging head and the fitting. By transmitting a force to the circumferential direction of the first rotating member and the second rotating member in a direction intersecting with the center line of the fitting member between the first and second rotating members, A power transmission device that transmits torque to and from two rotating members is known. The power transmission device described in Patent Document 1 is an example thereof, and the engaging head has a flat plate shape, and a notch for receiving the engaging head is provided in the fitting member. By inserting the engaging head and rotating it relative to each other by 90 °, both are engaged with each other so that they cannot be pulled out.
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 3-277824
[Problems to be solved by the invention]
However, in such a power transmission device in which a fitting member is provided with a notch so that both are fitted, the posture of the fitting member needs to be positioned at a fixed phase by a rail or the like, and the structure becomes complicated. There is a problem that power loss is increased due to friction or durability is impaired.
[0005]
On the other hand, for example, as shown in FIG. 4A, at least one of the spherical engagement head 100 and the fitting member 102 can be elastically deformed and press-fitted and fitted. It is necessary to reduce the press-fitting allowance t, and stress concentration may occur in the end portion 102a on the fitting front end side, which may cause early wear or damage. That is, when the torque is transmitted, the contact ellipse 104 is generated by the elastic deformation as shown by hatching in the engagement head 100 in FIG. 4B. However, when the press-fitting allowance t is small, the contact ellipse 104 protrudes from the fitting member 102 and contacts. A part of the ellipse 104 is cut out, and stress concentration occurs in the end portion 102a. The dotted line in FIG. 4B is the contact ellipse 104 when the fitting member 102 is sufficiently large.
[0006]
The present invention has been made against the background of the above circumstances. The object of the present invention is to squeeze out the contact ellipse during power transmission in a power transmission device of a type in which the engagement head and the fitting member are press-fitted and fitted. The purpose is to prevent stress concentration due to.
[0007]
[Means for Solving the Problems]
In order to achieve such an object, the first invention includes: (a) an engagement head provided on the first rotating member so as to be spaced from the rotation center; and (b) provided substantially concentrically with the first rotating member. And a fitting member provided with a fitting concave surface that is provided on the second rotating member so as to be spaced apart from the center of rotation and that is brought into spherical contact with the engaging head and is fitted so as to be relatively rotatable. And (c) force is applied between the engaging head and the fitting member in a direction intersecting a center line of the fitting member in the circumferential direction of the first rotating member and the second rotating member. In the power transmission device that transmits torque between the first rotating member and the second rotating member by transmitting, (d) the fitting concave surface and the engaging head are formed by the fitting member. Two contact portions located on both sides of the center point of the engaging head in the fitting direction which is the center line direction One of them has an angular contact shape so that they are in contact with each other, and the fitting member and the engaging head are press-fitted in the fitting direction and joined together while elastically deforming at least one of them. On the other hand, (e) either one of the fitting member and the engaging head is disposed non-rotatably around its own center line, and the fitting member of the two contact portions The contact portion that is in contact with the front end of the fitting is provided with a relief so that the contact pressure at the time of transmission of the force is reduced or zero at a portion located in the force transmission direction. It is characterized by that.
[0008]
In addition, the angular contact shape is different in curvature between the engaging head and the fitting concave surface in the cross section including the center line, and is bent in the middle so as to contact at two points separated in the center line direction. When the fitting concave surface is specifically described, the large diameter sides of a pair of rotating arc surfaces obtained by rotating an arc having a smaller curvature than the spherical engaging head around the center line are mutually abutted. Or the shape which abutted the large diameter side of a pair of truncated conical surface mutually. Further, in the case of the engaging head, a shape provided with a pair of annular ridges obtained by rotating an arc having a larger curvature than the partially spherical fitting concave surface around the center line, or a cross section including the center line. A rectangular shape or a trapezoidal shape, such as a disk shape in which an R-shaped corner having a larger curvature than the fitting concave surface is brought into contact with the fitting concave surface.
[0009]
According to a second aspect of the present invention, (a) three or more balls that protrude in the radial direction at three or more locations around the rotation center line of the first rotating member and each have a spherical engaging head at the tip thereof And (b) at least three corresponding to the three or more ball members are disposed on the second rotating member provided substantially concentrically with the first rotating member, and each of the second rotating member is rotated relative to the engaging head. A fitting member having a fitting concave surface to be movably fitted, and (c) the engaging head while allowing the first rotating member and the second rotating member to swing. By transmitting a force in the direction intersecting the center line of the fitting member and the circumferential direction of the first rotating member and the second rotating member between the fitting member and the fitting member. In the power transmission device that transmits torque between the member and the second rotating member, (d) the fitting concave surface is An angular contact shape that contacts the engagement head at two contact portions located on both sides of the center point of the engagement head in the fitting direction, which is the center line direction of the fitting member, The fitting member and the engaging head are pressed and joined in the fitting direction while elastically deforming at least one of the fitting member and the engaging head. (E) The ball member is non-rotatably arranged around its own center line. And a portion of the engagement head that is in contact with the contact portion on the engagement distal end side of the engagement member, on both sides positioned in the force transmission direction, A pair of reliefs are provided so that the contact pressure with the fitting concave surface is reduced or zero during transmission.
[0010]
The third invention has an engaging head and a fitting member having a fitting concave surface which is brought into spherical contact with the engaging head and is fitted so as to be relatively rotatable. In the ball coupling structure that transmits a force in a direction intersecting with the center line of the fitting member between the portion and the fitting member, (a) the fitting concave surface and the engagement head are formed of the fitting member. Either one of them forms an angular contact shape so that the two contact portions located on both sides of the center point of the engaging head in the fitting direction, which is the center line direction, are in contact with each other. The combined member and the engaging head are pressed and coupled in the fitting direction while elastically deforming at least one of the combined member and (b) either the fitting member or the engaging head is itself And the non-rotatable arrangement around the center line of the two contact portions. That is, the contact portion that contacts the fitting distal end side of the fitting member, and that is located in the force transmission direction, is relieved so that the contact pressure at the time of transmission of the force is reduced or becomes zero. Is provided.
[0011]
【The invention's effect】
According to the power transmission device of the first and second inventions, the fitting concave surface of the fitting member and the fitting concave surface of the fitting member so as to contact at two contact portions located on both sides of the center point of the engagement head in the fitting direction. Either one of the engaging heads (the fitting concave surface in the second invention) has an angular contact shape, while either one of the engaging head or the fitting member (the engaging head in the second invention). Is disposed non-rotatably around the center line, and a portion located on the fitting tip side of the fitting member and located in the force transmission direction is provided with a relief. The contact ellipse protrudes from the mating member during force transmission and stress concentration occurs at the end on the mating tip side, regardless of the coupling by press-fitting. Is prevented and premature wear and damage is avoided. Further, at the portion other than the relief, the fitting tip side of the fitting member and the engagement head are brought into contact with each other, and the fitting direction is a direction intersecting with the force transmission direction. Pull-out is prevented and the bonded state is maintained well.
[0012]
The third invention relating to the coupling structure of the engaging head and the fitting member does not necessarily transmit power, but, like the first invention and the second invention, is concerned with the coupling by press fitting. When the shear force is transmitted, the contact ellipse protrudes from the fitting member and stress concentration is prevented from occurring at the end of the fitting tip, preventing premature wear and damage. By bringing the mating tip side and the mating head into contact with each other, the slipping in the direction opposite to the mating is prevented, and the coupled state is maintained well.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is preferably applied to a power transmission device that transmits torque, such as a tripod joint, but in the third invention, it is not necessarily a rotational motion, and a power transmission device that transmits a linear motion or a force transmission. The present invention can be applied to various ball connection structures such as a ball joint having a substantially constant direction. The second invention corresponds to one embodiment of the first invention, and the first invention and the second invention correspond to one embodiment of the third invention.
[0014]
In the second invention, the ball member protrudes in the radial direction of the first rotating member, and it is desirable to protrude in the direction orthogonal to the rotation center line. However, it only has to include a radial component. It is also possible to project so as to incline in the axial direction or the circumferential direction. Moreover, although it protrudes in a shaft member etc. so that it may go to a radial direction outer side, it can also be provided in a cylindrical member etc. so that it may go to a radial direction inside. In the first invention, it is also possible to provide the engaging head by protruding the ball member in the axial direction parallel to the rotation center line, and the engaging head and the fitting member are brought close to each other in the axial direction. It can also be configured to fit.
[0015]
The three or more ball members according to the second aspect of the invention can be provided integrally at regular angular intervals, for example, on a single sleeve or the like, but various aspects can be provided such as being separated in the axial direction and provided separately. Is possible. Also in the first invention, three or more sets of engaging heads and fitting members that are press-fitted to each other can be provided, but only two sets or one set may be provided.
[0016]
The fitting direction between the engagement head and the fitting member, that is, the posture of the fitting member, may be such that its center line intersects with the force transmission direction. A direction substantially perpendicular to the force transmission direction is desirable. For example, in the first invention and the second invention, in order to transmit force in the rotational direction of the first rotating member and the second rotating member, that is, in the circumferential direction, it is fitted with a radial direction substantially orthogonal to the rotation center line of the second rotating member. It is desirable to dispose in a posture that substantially matches the center line of the combined member. In the first aspect of the invention, the rotation center line of the second rotation member and the center line of the fitting member can be arranged in a substantially parallel posture.
[0017]
When the first rotating member and the second rotating member are connected so as to be swingable as in the second invention, for example, one of the ball member and the fitting member is parallel to the rotation center line of the rotating member. The ball member and the fitting member can be moved in a direction parallel to the rotation center line of the rotating member. The other may be arranged so as to be movable in the radial direction perpendicular to the rotation center line of the rotating member. In the first invention, the first rotating member and the second rotating member do not necessarily need to be swingable.
[0018]
When the fitting member is disposed so as to be movable in a direction parallel to the rotation center line of the second rotating member, a rotating roller is provided via a bearing such as a needle bearing, and the rotating roller is brought into contact with the rotating member to rotate. It is desirable to make it move while moving. In that case, since the fitting member can rotate around its own center line, that is, the center line in the fitting direction, the ball member is disposed in a non-rotatable manner as in the second aspect of the invention, and the ball member is allowed to escape. It only has to be provided. In the first aspect of the invention, the engaging head is disposed so as to be rotatable around a center line parallel to the fitting direction, while the fitting member is disposed so as not to be rotatable, and the fitting concave surface of the fitting member. You may make it provide relief.
[0019]
The spherical contact between the engaging head and the mating concave surface in the first and third inventions is such that either the engaging head or the mating concave surface is a spherical surface and is three-dimensional with respect to the spherical center. This means that relative rotation is possible. The angular contact shape engaged with the spherical surface is preferably a rotating circular arc surface having a curvature close to that of the spherical surface so that the load distribution in the contact region gradually changes in terms of wear and durability.
[0020]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1A and 1B are diagrams for explaining a main part of a tripod joint 10 as a power transmission device to which the present invention is applied. FIG. 1A is a cross-sectional view parallel to the axial direction, and FIG. 1B is a cross-sectional view perpendicular to the axial direction. (A) is a half on one side of the rotation center lines O ₁ and O ₂ , and (b) is a diagram showing an angle range of about 1/3 around the rotation center lines O ₁ and O ₂ . The tripod joint 10 is configured to transmit rotation by connecting the first rotating member 12 and the second rotating member 14 arranged substantially concentrically so as to be swingable as indicated by an arrow A. The member 12 is spline-fitted with a sleeve 18 that is integrally provided so that the three ball members 16 protrude toward the outer peripheral side at equal angular intervals (120 ° intervals). Ball member 16, together protrudes in a radial direction substantially perpendicular to the rotational axis O ₁ is the axis of the first rotary member 12, the engaging head 20 is integral to the front end portion forming a spherical shape Is provided.
[0021]
The second rotating member 14 is integrally provided with a large-diameter connecting cylindrical portion 22 at the end, and three fitting members corresponding to the three ball members 16 are provided in the connecting cylindrical portion 22. 24 are arranged at equal angular intervals (120 ° intervals) around the rotation center line O ₂ that is the axis of the second rotation member 14. Each of the fitting members 24 has an annular shape having a fitting concave surface 26 corresponding to the engagement head 20, and is press-fitted to the engagement head 20 so as to be relatively rotatable in three dimensions. In addition, a rotating roller 30 is disposed on the outer peripheral side of the fitting member 24 via a needle bearing 28 so as to be relatively rotatable and to be relatively movable in the direction of the center line L (see FIG. 2). The rotating roller 30 is disposed in a guide groove 32 provided in parallel to the rotation center line O ₂ on the inner peripheral surface of the connecting cylindrical portion 22, and is positioned at a predetermined position around the rotation center line O ₂ . While rotating in contact with one side wall of the guide groove 32 in a substantially constant posture, it is allowed to reciprocate in a direction parallel to the rotation center line O ₂ while being guided by the guide groove 32.
[0022]
The fitting member 24 is positioned at a predetermined position around the rotation center line O ₂ via the rotating roller 30, and is thus positioned in a direction perpendicular to the center line L between the engagement head 20 and the engagement head 20. Force is transmitted in the circumferential direction of the first rotating member 12 and the second rotating member 14, that is, in the left-right direction in FIG. 1B, and rotation (torque) is transmitted between the first rotating member 12 and the second rotating member 14. Is done. The fitting member 24 is allowed to move in the direction parallel to the rotation center line O ₂ together with the rotation roller 30, and the diameter at which the center line L is substantially orthogonal to the rotation center line O ₂ by the rotation roller 30. Since it is positioned in a posture that substantially coincides with the direction (vertical direction in FIGS. 1A and 1B) and can move relative to the rotary roller 30 in the radial direction, While maintaining the fitted state, the swing A between the first rotating member 12 and the second rotating member 14 is allowed, and the first rotating member 12 and the second rotating member remain swinging and tilting. Rotation can be transmitted to and from 14. Instead of allowing the fitting member 24 to move relative to the rotating roller 30 in the radial direction of the second rotating member 14 (the vertical direction in FIGS. 1A and 1B), the rotating roller 30 is not attached to the rotating roller 30. The rotation member 14 may be arranged so as to be movable in the radial direction, and the fitting member 24 and the rotation roller 30 may be integrally moved in the radial direction.
[0023]
Here, the fitting member 24 and the engagement head 20 are elastically deformed at least one, and are fitted in the fitting direction parallel to the center line L of the fitting member 24 (the upper and lower sides in FIGS. 2A and 2B). In order to prevent yielding during assembly, the dimension below the fitting distal end side of the fitting concave surface 26, that is, the center point (sphere center) S of the engaging head 20 is A small tapered surface 34 is provided on the peripheral edge of the opening on the fitting tip side. Further, the fitting concave surface 26 of the fitting member 24 is formed by two contact portions PC1 and PC2 located on both sides of the center point S of the engagement head 20 in the fitting direction, as shown in an enlarged view in FIG. An angular contact shape is formed by joining two rotating circular arc surfaces 26a and 26b in the middle of the center line L direction (vertical direction in FIGS. 2A and 2B) so as to come into contact with the engaging head 20. ing. As shown in FIGS. 2 (a) and 2 (b), the two rotating arc surfaces 26a and 26b each have an arc having a curvature slightly smaller than the curvature of the engaging head 20 in the cross section including the center line L. In the shape rotated around, the center of curvature of the rotating arc surface 26a is located on the fitting tip side (lower side of FIGS. 2A and 2B) from the center point S, and the center of curvature of the rotating arc surface 26b. Is located on the opposite side of the center line S from the front end of the fitting (the upper side of FIGS. 2A and 2B), and the center of the rotating arc surfaces 26a and 26b in the direction of the center line L. The annular portion located at the position is brought into contact with the engagement head 20 as the contact portions PC1 and PC2. 2 (a) and 2 (b) correspond to FIGS. 1 (a) and 1 (b), respectively, and FIG. 2 (c) shows an engaging head corresponding to the CC cross section in FIG. 2 (b). FIG.
[0024]
On the other hand, the ball member 16 disposed on the first rotating member 12 by spline fitting cannot rotate around its center line, and the fitting tip of the fitting member 24 of the engagement head 20 is not possible. The side corresponding to the contact portion PC2 on the side and located on both sides located in the force transmission direction, that is, the left and right sides in FIGS. A pair of reliefs 40a and 40b are provided so as not to contact the two. The reliefs 40a and 40b are obtained by removing the surface layer portion of the engaging head 20 with a substantially constant depth, and both have a substantially spherical shape.
[0025]
Therefore, when the rotation is transmitted between the first rotating member 12 and the second rotating member 14, the engagement head 20 and the fitting member 24 are transmitted with force only through one contact portion PC1. 2B, the contact ellipse 36 does not protrude from the fitting member 24 like the contact ellipse 36 indicated by hatching in the engagement head 20 in FIG. The size of the rotating arc surface 26 a of the fitting concave surface 26 is set in consideration of elasticity, transmission load, and the like so that the contact ellipse 36 does not protrude from the fitting member 24 in this way. Further, the portions other than the reliefs 40a and 40b are engaged with each other because the engaging head 20 is brought into contact with the contact portion PC2 on the fitting distal end side of the fitting member 24 as shown in FIG. Prevents slipping out in the direction opposite to the fitting. The fitting direction of the engagement head 20 and the fitting member 24 is a radial direction substantially orthogonal to the rotation center lines O ₁ and O ₂ , whereas the force transmission direction is the rotation center lines O ₁ and O 2. _{Since there are two} circumferential directions, there is no fear that a large force will act in the pulling direction of the engaging head 20 and the fitting member 24 during rotation transmission. The bonded state is maintained well.
[0026]
Thus, according to the tripod joint 10 of the present embodiment, the fitting member 24 is brought into contact with the two contact portions PC1 and PC2 located on both sides of the center point S of the engagement head 20 in the fitting direction. The engagement concave surface 26 is formed in an angular contact shape, while the engagement head 20 is a portion corresponding to the contact portion PC2 on the engagement distal end side of the engagement member 24 and is positioned in the force transmission direction. Since the pair of reliefs 40a and 40b are provided in the portion to be engaged and cannot be brought into contact with the contact portion PC2 at the time of transmission of the force, the engagement area on the fitting tip side is small, and the connection by press fitting is involved. As shown in FIG. 2B, the contact ellipse 36 does not protrude from the fitting member 24, and early wear and damage due to stress concentration are avoided.
[0027]
Further, at portions other than the reliefs 40a and 40b, the engagement head 20 is brought into contact with the contact portion PC2 on the engagement distal end side of the engagement member 24, and the engagement direction thereof is the transmission of force at the time of rotation transmission. Since the direction is substantially perpendicular to the direction, there is no fear that a large force acts in the pulling direction of the engaging head 20 and the fitting member 24 at the time of transmission of rotation. The combined state is maintained well.
[0028]
In addition, the connection structure of the engagement head 20 and the fitting member 24 in the above embodiment corresponds to the ball connection structure of claim 3.
[0029]
In the above-described embodiment, the spherical reliefs 40a and 40b are provided. However, various modes are possible such as provision of cylindrical reliefs 42a and 42b as shown in FIG. 3A is a view corresponding to FIG. 1B, and FIG. 3B is a cross-sectional view of the engagement head 20 corresponding to the BB cross section in FIG. 3A.
[0030]
As mentioned above, although the Example of this invention was described in detail based on drawing, this is an embodiment to the last, and this invention is implemented in the aspect which added various change and improvement based on the knowledge of those skilled in the art. Can do.
[Brief description of the drawings]
FIGS. 1A and 1B are views showing a main part of a tripod joint according to an embodiment of the present invention, in which FIG. 1A is a cross-sectional view parallel to the axis and FIG. 1B is a cross-sectional view perpendicular to the axis.
FIGS. 2A and 2B are diagrams for explaining an engaging head and a fitting member of the tripod joint of FIG. 1, and FIGS. 2A and 2B are views corresponding to FIGS. 1A and 1B; FIG. These are figures equivalent to the CC cross section in (b).
FIGS. 3A and 3B are diagrams for explaining another embodiment of the present invention, in which FIG. 3A is a cross-sectional view corresponding to FIG. 1B, and FIG. 3B is a view corresponding to the cross section BB in FIG. .
FIGS. 4A and 4B are diagrams for explaining a fitting state of an engagement head and a fitting member of a conventional tripod joint, in which FIG. 4A is a cross-sectional view showing a press-fitting allowance t, and FIG. It is sectional drawing.
[Explanation of symbols]
10: tripod joint (power transmission device) 12: first rotating member 14: second rotating member 16: ball member 20: engaging head 24: fitting member 26: fitting concave surface 40a, 40b, 42a: 42b: escape PC1, PC2: contact portion O ₁ : rotation center line of the first rotation member O ₂ : rotation center line of the second rotation member L: center line of the fitting member S: center point

Claims (3)

An engaging head provided on the first rotating member apart from the center of rotation;
A fitting concave surface which is provided on a second rotating member provided substantially concentrically with the first rotating member and spaced from the center of rotation, and is brought into spherical contact with the engaging head so as to be relatively rotatable. A fitting member comprising:
And transmitting force to the circumferential direction of the first rotating member and the second rotating member in a direction intersecting with the center line of the fitting member between the engaging head and the fitting member. In the power transmission device that transmits torque between the first rotating member and the second rotating member,
The fitting concave surface and the engaging head come into contact with each other at two contact portions located on both sides of the center point of the engaging head in the fitting direction which is the center line direction of the fitting member. Any one of them has an angular contact shape, and the fitting member and the engagement head are pressed and joined in the fitting direction while elastically deforming at least one of the fitting member and the engagement head,
Either one of the fitting member and the engagement head is disposed so as not to rotate around the center line of the engagement member and the engagement tip side of the engagement member among the two contact portions. A contact portion that is in contact with the force and that is located in the force transmission direction is provided with relief so that the contact pressure during transmission of the force is reduced or zero. Transmission device. Three or more ball members that protrude in the radial direction at three or more locations around the rotation center line of the first rotation member, and each have a spherical engagement head at the tip;
Three or more second rotation members provided substantially concentrically with the first rotation member are disposed corresponding to the three or more ball members, and are fitted to the engagement heads so as to be relatively rotatable. A fitting member having a fitting concave surface;
The first rotating member and the second rotating member are allowed to swing while crossing the center line of the fitting member between the engagement head and the fitting member. A power transmission device that transmits torque between the first rotating member and the second rotating member by transmitting a force in a circumferential direction of the first rotating member and the second rotating member;
The engagement concave surface is an angular contact that comes into contact with the engagement head at two contact portions located on both sides of the center point of the engagement head in the engagement direction that is the center line direction of the engagement member. The fitting member and the engagement head are pressed and joined in the fitting direction while elastically deforming at least one of the fitting member and the engagement head,
The ball member is non-rotatably disposed around its own center line, and is a portion of the engagement head that is in contact with a contact portion on the fitting tip side of the fitting member, A power transmission characterized in that a pair of reliefs are provided on both sides located in the force transmission direction so that the contact pressure with the fitting concave surface is reduced or zero when the force is transmitted. apparatus. An engaging head, and a fitting member having a fitting concave surface that is brought into spherical contact with the engaging head and is fitted so as to be relatively rotatable, the fitting head and the fitting In the ball connection structure that transmits force in a direction intersecting the center line of the fitting member between the members,
The fitting concave surface and the engaging head come into contact with each other at two contact portions located on both sides of the center point of the engaging head in the fitting direction which is the center line direction of the fitting member. Any one of them has an angular contact shape, and the fitting member and the engagement head are pressed and joined in the fitting direction while elastically deforming at least one of the fitting member and the engagement head,
Either one of the fitting member and the engagement head is disposed so as not to rotate around the center line of the engagement member and the engagement tip side of the engagement member among the two contact portions. A contact portion that is in contact with the force and is located in the force transmission direction is provided with relief so that the contact pressure during force transmission is reduced or zero. Linked structure.

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