WO2021172737A1

WO2021172737A1 - Tripod joint

Info

Publication number: WO2021172737A1
Application number: PCT/KR2021/000234
Authority: WO
Inventors: 천명길; 장달수; 이광진
Original assignee: 이래에이엠에스 주식회사
Priority date: 2020-02-27
Filing date: 2021-01-08
Publication date: 2021-09-02
Also published as: KR20210109227A

Abstract

A tripod joint comprises: an inner joint member having three journals protruding outward in the radial direction; three roller assemblies each including an inner roller coupled to the journal and an outer roller arranged so as to enclose the inner roller; and an outer joint member having three roller grooves that accommodate the roller assemblies, respectively, and form facing roller tracks. The roller tracks and the outer rollers are configured so as to contact each other at two contact points during torque transmission, the two contact points being symmetrical with respect to the central plane of the roller track extending parallel to the lengthwise axis of the outer joint member. The journals are configured such that, during the torque transmission in the state of maximum articulation of the outer joint member and the inner joint member, the center of action passes through each of the two contact points and moves in a region between the inner and outer reference planes parallel to the central plane.

Description

tripod joint

The present invention relates to a constant velocity joint used in a drive system of a vehicle, and more particularly, to a plunging type tripod joint that allows axial displacement.

The tripod joint includes an inner joint member having three journals, three roller assemblies each assembled to the journals, and an outer joint member forming three roller grooves for accommodating the roller assemblies ( outer joint member).

The outer joint member forms a central through hole into which the inner joint member is inserted, and each roller groove is formed by recessing radially outward from the central through hole of the outer joint member. Each roller groove forms an opposing roller track, and when the joint is operated, the outer roller of the roller assembly is pressed against one of the roller tracks according to the torque transmission direction to transmit torque.

During joint operation, NVH performance deteriorates due to fluctuations generated when the outer roller moves along the roller track during joint operation, and generated axial force (GAF), an axial force acting on the outer joint member due to friction, is generated. In particular, the magnitude and direction of the moment vary depending on the relative position between the contact point of the outer roller and the roller track and the center of the journal.

US Patent Publication No. US2006/0105845 (published on: May 18, 2006)

The problem to be solved by the present invention is to provide a tripod joint that provides improved NVH performance and GAF performance by minimizing unnecessary movement of the outer roller during torque transmission.

A tripod joint according to an embodiment of the present invention includes an inner joint member having three journals protruding radially outward, an inner roller fastened to the journal, and an outer roller arranged to surround the inner roller. an outer joint member having four roller assemblies and three roller grooves each receiving the roller assemblies and forming opposite roller tracks. The roller track and the outer roller are configured to contact at two contact points symmetrical with respect to a center plane of the roller track extending parallel to the longitudinal axis of the outer joint member during torque transmission. The journal is configured to move in the area between the inner and outer reference planes parallel to the center plane, respectively, while the center of action passes through the two contact points when torque is transmitted in the maximum cleavage state of the outer joint member and the inner joint member. .

The roller track may include an outer convex region disposed outside of the central plane and an inner convex region disposed inside the central plane to be symmetrical with the outer convex region with respect to the central plane, wherein the outer roller comprises: and an outer concave region formed to correspond to the outer convex region to form one of the two contact points and an inner concave region formed to correspond to the inner convex region to form the other one of the two contact points.

An extension line in the direction of the force applied at the two contact points may be configured to meet on the central plane.

The working center point of the journal may be configured to be located on the center plane in a non-engraved state between the inner joint member and the outer joint member.

The outer circumferential surface of the journal may be formed as a spherical surface, and the working center point may coincide with a geometric center of the spherical surface.

The working center point of the journal may be offset radially outward from the center plane in a non-engraved state of the inner joint member and the outer joint member.

A tripod joint according to another embodiment of the present invention includes an inner joint member having three journals protruding outward in a radial direction, an inner roller fastened to the journal, and an outer roller arranged to surround the inner roller and an outer joint member comprising three roller assemblies and three roller grooves each receiving the roller assemblies and forming opposite roller tracks. The roller track and the outer roller are configured to contact at two contact points symmetrical with respect to a center plane of the roller track extending parallel to the longitudinal axis of the outer joint member during torque transmission. In the journal, an action center point is located on the center plane in the non-engraved state of the outer joint member and the inner joint member, and the maximum displacement in the radial direction in the maximum cut-out state of the outer joint member and the inner joint member is the center It is configured to be smaller than the distance between the surface and the contact point.

An extension line in a direction of force applied at the two contact points during torque transmission may be configured to meet on the central plane.

According to the present invention, unnecessary motion of the outer roller can be minimized by placing the displacement area of the working center point of the journal between the reference planes passing the contact point, thereby improving NVH performance and GAF performance.

1 is a schematic perspective view of a tripod joint according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1 .

3 is a perspective view showing an exploded state of one of the roller assemblies fastened to the inner joint member of the tripod joint according to the embodiment of the present invention.

FIG. 4 is an enlarged view inside the dotted line of FIG. 2 .

5 is a view for explaining the positional relationship between the contact point of the outer joint member and the action center point of the journal of the inner joint member in FIG. 4 .

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 to 3 , a tripod joint according to an embodiment of the present invention includes an outer joint member 10 and an inner joint member 20 .

1 and 2, the outer joint member 10 has a longitudinal axis OLA, and a central cavity 11 extending along the longitudinal axis OLA and three roller grooves ( 12) is provided.

The central cavity 11 may have a substantially cylindrical shape, and the roller groove 12 has a recess shape recessed radially outward from the central cavity 11 and extends in the longitudinal direction. At this time, the three roller grooves 12 are arranged at equal intervals along the circumferential direction.

The inner joint member 20 is disposed in the central cavity 11 of the outer joint member 10 . The inner joint member 20 includes a central body 21 and three journals 22 projecting radially outward from the central body 21 . Each journal 22 projects radially outward from the central body 21 to form a radial axis JRA. At this time, as shown in FIG. 2 , the three journals 22 are arranged at equal intervals along the circumferential direction and are respectively arranged in the roller grooves 12 of the outer joint member 10 .

A shaft 23 is fastened to the central body 21 , the shaft 23 having a longitudinal axis ILA. The shaft 23 may be fastened to the central body 21 to rotate together with the central body 21 , for example, to the central body 21 in a spline manner.

Three roller assemblies 30 are each fastened to three journals 22 . 1 and 2 , the roller assembly 30 is disposed in the roller groove 12 of the outer joint member 10 while being fastened to the journal 22 of the inner joint member 20 . The tripod joint according to the embodiment of the present invention performs a torque transmission function between the outer joint member 10 and the inner joint member 20 via the roller assembly 30 .

At this time, the roller assembly 30 is fastened to the journal 22 so that the longitudinal axis ILA of the inner joint member 20 can be angled with respect to the longitudinal axis OLA of the outer joint member 10 . Further, the roller assembly 30 is disposed in the roller groove 12 to enable displacement along the direction parallel to the longitudinal axis OLA along the roller groove 12 .

Each roller assembly 30 includes an inner roller 31 , an outer roller 32 , a needle bearing 33 and a retaining ring 34 . do.

The inner roller 31 and the outer roller 32 each have a ring shape, and the outer roller 32 is disposed to surround the inner roller 31 . The retaining ring 34 has an outer end inserted into the recessed groove 322 formed on the inner circumferential surface 321 of the outer roller 32 to support both ends of the needle bearing 32, respectively. The inner end supports both ends of the inner roller 31 . The relative movement in the longitudinal direction of the journal 22 of the inner roller 31 , the outer roller 32 and the needle bearing 33 is blocked by the restraint of the retaining ring 34 . At this time, the outer peripheral surface 312 of the inner roller 31 and the inner peripheral surface 321 of the outer roller 32 may have a cylindrical shape, and the needle bearing 33 may have a cylindrical shape. The plurality of needle bearings 33 may be arranged in a circumferential direction about the longitudinal axis of the journal 22 in a state in which they are aligned in parallel with the longitudinal direction of the journal 22 , respectively.

The inner peripheral surface 311 and the outer peripheral surface 312 of the inner roller 31 may each have a cylindrical shape, and the inner peripheral surface 311 of the inner roller 31 is in contact with the spherical outer peripheral surface 221 of the journal 22 . Thereby, the journal 22 is movable relative to the inner roller 31 in the radial direction, whereby the journal 22 transmits torque while changing its radial position relative to the inner roller 31 when operating in the truncated state. can

Each roller groove 12 forms a pair of

roller tracks

121 and 122 facing each other. Torque is transmitted through contact between any one of the

roller tracks

121 and 122 facing each other according to the torque transmission direction and the outer peripheral surface of the outer roller 32 . For example, when the outer joint member 10 transmits torque to the inner joint member 20 while rotating clockwise about the longitudinal axis OLA in FIG. 4 , the roller track shown on the left side of FIG. 4 . Torque transmission is made by contacting the outer peripheral surface of the 121 and the outer roller 32, which will be described below based on this case. Conversely, when the outer joint member 10 transmits torque to the inner joint member 20 while rotating counterclockwise about the longitudinal axis OLA in FIG. 4, the roller track shown on the right side of FIG. 122) and the outer peripheral surface of the outer roller 32 come into contact with each other to transmit torque.

The roller track 121 and the outer roller 32 have two contact points (P1, P2) that are symmetrical with respect to the longitudinal axis (OLA) of the outer joint member (10) and the central plane (CS) extending in parallel when the torque is transmitted. is configured to come into contact with The roller track 121 may include an outer convex region 1211 and an inner convex region 1212 respectively disposed on the radially outer and inner sides of the central plane CS, the outer convex region 1211 and the inner convex region, respectively. 1212 may be symmetrical about the central plane CS. The outer peripheral surface 323 of the outer roller 32 may include an outer concave region 3231 formed to correspond to the outer convex region 1211 and an inner concave region 3232 formed to correspond to the inner convex region 1212. have. During torque transmission, the outer convex region 1211 and the outer concave region 3231 contact each other at the outer contact point P1, and the inner convex region 1212 and the inner concave region 3232 contact each other at the inner contact point P2. At this time, the extension line in the action direction of the forces F1 and F2 acting on the two contact points P1 and P2 for torque transmission is configured to meet at a point FP1 on the central plane CS. The outer convex region 1211 may include a circular arc defined by a predetermined radius centered on the center of curvature C1 , and the inner convex region 1212 is defined by a predetermined radius centered on the center of curvature C2 . It may include an arc that becomes At this time, as shown in FIG. 4 , the center of action OP located on the longitudinal axis JRA of the journal 22 is the center plane in the non-engraved state of the outer joint member 10 and the inner joint member 20 . It can be located on (CS). The working center point OP of the journal 22 may be the geometric center of the outer circumferential surface of the spherical journal 22 . On the other hand, in another embodiment of the present invention, the working center point of the journal 22 may be offset radially outward from the center plane of the roller track 121 (offset upward in FIG. 4 ).

The action center point OP of the journal 22 moves radially inward with respect to the roller assembly 30 and the outer joint member 10 by the engraving, and the operation in the notch state, that is, the rotation of the journal 22 according to the rotation. It reciprocates along a predetermined trajectory along the radial direction. Referring to FIG. 5 , the working center point (OP) of the journal disposed _{at the initial position (P c ) in the non-engraved state moves radially inwardly by the cutting angle.} At this time, assuming that the journal is a journal located in the 12 o'clock direction in FIG. 2 and is engraved in the downward direction, the working center point OP of the journal moves inward in the radial direction to move to the point P _i and rotates The point P _i is located at the innermost radial direction. When rotating in such a jeep state, the working center point (OP) of the journal _{is located at the innermost point (P i} ) when it is at the top (that is, a rotation angle of 0 degrees) with respect to FIG. (P _c ), the outermost point (P _o ) when rotated 180 degrees, the initial point (P _c ) again when rotated 270 degrees, and the innermost point (P _i ) again when rotated 360 degrees. During the torque transmission operation in the non-slit state, the action center point OP of the journal 22 repeats this trajectory. At this time, according to the geometrical calculation, the distance between the _{first point (P c} ) and the innermost point (P _i ) is three times the distance between the _{first point (P c} ) and the outermost point (P _{o ).}

On the other hand, according to another aspect of the embodiment of the present invention, referring to FIG. 5 , the working center point OP of the journal 22 is the maximum displacement in the radial direction in the maximum notch state, that is, in the direction of 12 o'clock in FIG. 2 . be configured such that the maximum displacement in the radial direction ( _{distance between point P c} and point P _i ) of the working center point of the located journal is less than the distance between the center plane CS of the roller track 121 and the contact point P2 . can

At this time, the operating center point OP of the journal 22 is the center of the roller track 121 while passing through the two contact points P1 and P2 when operating in the maximum notch state of the outer joint member 10 and the inner joint member 20 . It is configured to move in a region between the inner reference plane IRS and the outer reference plane ORS parallel to the plane CS. _{That is, in FIG. 5, the innermost point (P i} ) and the outermost point (P _o ) of the trajectory of the working center point (OP) of the journal 22 in the maximum notch state are located between the two reference planes (IRS, ORS). is composed When the action center point OP of the journal 22 is out of the area between the inner and outer reference planes IRS, ORS, the moment acting on the roller assembly 30 by the journal 22 increases, and the GAF and NVH performance deteriorates. Therefore, in the embodiment of the present invention, when operating in the maximum notch state, the GAF and NVH performance degradation can be prevented by allowing the working center point OP of the journal 22 to move between the two reference planes IRS and ORS. can

Although the embodiment of the present invention has been described above, the scope of the present invention is not limited thereto, and it is easily changed by a person skilled in the art from the embodiment of the present invention and recognized as equivalent. including all changes and modifications to the scope of

Since the present invention relates to a tripod constant velocity joint that can be applied to a drive system of a vehicle, it has industrial applicability.

Claims

an inner joint member having three journals projecting radially outward;

three roller assemblies each including an inner roller fastened to the journal and an outer roller arranged to surround the inner roller, and

Outer joint member having three roller grooves each receiving the roller assembly and forming an opposing roller track

including,

The roller track and the outer roller are configured to contact at two contact points symmetrical with respect to a center plane of the roller track extending parallel to the longitudinal axis of the outer joint member during torque transmission,

The journal is configured to move in the area between the inner and outer reference planes parallel to the center plane, respectively, while the center of action passes through the two contact points when torque is transmitted in the maximum cleavage state of the outer joint member and the inner joint member

tripod joint.
In claim 1,

the roller track comprises an outer convex region disposed outside of the central plane and an inner convex region disposed inside of the central plane to be symmetrical with the outer convex region with respect to the central plane;

The outer roller includes an outer concave region formed to correspond to the outer convex region to form one of the two contact points and an inner concave region formed to correspond to the inner convex region to form the other one of the two contact points

tripod joint.
In claim 2,

A tripod joint configured such that an extension line in a direction of force applied at the two contact points meets on the center plane.
In claim 3,

The working center point of the journal is a tripod joint configured to be located on the center plane in a non-engraved state of the inner joint member and the outer joint member.
In claim 4,

A tripod joint in which the outer circumferential surface of the journal is formed as a spherical surface and the center of action coincides with the geometric center of the spherical surface.
In claim 4,

The working center point of the journal is a tripod joint that is offset radially outward from the center plane in a non-engraved state of the inner joint member and the outer joint member.
an inner joint member having three journals projecting radially outward;

three roller assemblies each including an inner roller fastened to the journal and an outer roller arranged to surround the inner roller, and

Outer joint member comprising three roller grooves each accommodating the roller assembly and forming an opposing roller track

including,

The roller track and the outer roller are configured to contact at two contact points symmetrical with respect to a center plane of the roller track extending parallel to the longitudinal axis of the outer joint member during torque transmission,

In the journal, an action center point is located on the center plane in the non-engraved state of the outer joint member and the inner joint member, and the maximum displacement in the radial direction in the maximum cut-out state of the outer joint member and the inner joint member is the center configured to be less than the distance between the face and the contact point

tripod joint.
In claim 7,

A tripod joint configured such that an extension line in a direction of force applied at the two contact points meets on the center plane during torque transmission.
In claim 7,

A tripod joint in which the outer circumferential surface of the journal is formed as a spherical surface and the center of action coincides with the geometric center of the spherical surface.