JP2009250365A - Constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a constant velocity universal joint inhibiting heat generation in heavy load operation or high speed operation, improving durability, suppressing contact resistance between a cage and inner and outer rings owing to stable cage position, and improving constant velocity properties (reducing a torque loss rate). <P>SOLUTION: The axial offset of the curvature center O1 of a track groove 12 of an outer joint member and the curvature center O2 of a track groove 15 of an inner joint member are set to zero. The track groove 12 of the outer joint member and the track groove 15 of the inner joint member are inclined to each axial line. Inclination directions of track grooves 12A, 12B (15A, 15B) adjoining in a circumferential direction are contrary. The track groove 12 of the outer joint member and the track groove 15 of the inner joint member opposing the same are inclined to opposite directions with respect to the axial line. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fixed type constant velocity universal joint applied to automobiles and various industrial machines.

  Examples of the fixed type constant velocity universal joint include a bar field type (BJ) and an undercut free type (UJ) (Patent Document 1, Patent Document 2).

  As shown in FIGS. 16 and 17, the BJ type fixed type constant velocity universal joint is an outer joint member in which a plurality of track grooves 2 are formed on the inner spherical surface 1 at equal intervals in the circumferential direction along the axial direction. An outer ring 3, an inner ring 6 as an inner joint member in which a plurality of track grooves 5 paired with the track grooves 2 of the outer ring 3 are formed on the outer spherical surface 4 along the axial direction at equal intervals in the circumferential direction; A plurality of balls 7 that transmit torque between the track groove 2 and the track groove 5 of the inner ring 6 and a ball 7 that is interposed between the inner spherical surface 1 of the outer ring 3 and the outer spherical surface 4 of the inner ring 6. The cage 8 to hold | maintain is provided. A plurality of window portions 9 in which the balls 7 are accommodated are arranged in the cage 8 along the circumferential direction.

  In this fixed type constant velocity universal joint, the center of curvature O1 of the track groove 2 of the outer ring 3 and the center of curvature O2 of the track groove 5 of the inner ring 6 are axially separated by an equal distance f with respect to the joint center O including the ball center. The offset is reversed. By providing the track offset in this way, each of the track grooves 2 and 5 is shallow from the center in the axial direction on the bottom side of the outer ring and deep on the opening side of the outer ring. As a result, from the bottom side of the outer ring 3 A wedge-shaped ball track in which the radial interval gradually increases toward the opening side is formed.

  Incidentally, in the constant velocity universal joint shown in FIGS. 16 and 17, the number of the balls 7 is six, but in recent years, there are those having eight balls as shown in FIGS. This is to reduce the size of the ball 7 for the purpose of high performance and compactness, and suppress the decrease in load capacity per unit. The constant velocity universal joint shown in FIGS. 18 and 19 is the same as the constant velocity universal joint shown in FIGS. 16 and 17 except that the number of balls 7 is increased from six to eight. The same reference numerals are given and description thereof is omitted.

Conventionally, the track grooves of the inner ring and the outer ring are inclined in a spiral shape or in the axial direction, and the adjacent tracks are made plane-symmetric so that the contact force between the ball track and the ball can be suppressed, and the durability is improved. Proposals have been made.
Japanese Patent No. 3300633 Patent No. 3859264

  As described above, a wedge-shaped ball track is formed in the constant velocity universal joint shown in FIG. The ball 7 pushes the window portion 9 of the cage 8 by the wedge angle, and the cage 8 is smoothly operated. However, although the track offset is important in operating the cage 8, a force is applied only in the direction toward the opening of the joint, so that the inner spherical surface 1 of the outer ring 3 and the outer spherical surface 4 of the inner ring 6 and the outer outer spherical surface 8a of the cage, 8b is in a contact state, and when the load on the joint is high or when the joint rotates at a high speed, the joint generates heat and the durability decreases.

  That is, as shown in FIG. 20, a wedge angle τ is generated in the ball 7 due to an offset between the track groove 2 of the outer ring 3 and the track groove 5 of the inner ring 6. Due to the influence of the wedge angle τ, the ball 7 generates a pushing force W that is pushed out to the opening side. The cage 8 is operated by the pushing force W. Further, since the cage 8 is pressed against the opening by this pushing force W, the outer spherical surface 8 a of the cage 8 contacts the inner spherical surface 1 of the outer ring 3, and the inner spherical surface 8 b of the cage 8 is in contact with the outer spherical surface 4 of the inner ring 6. Contact. This contact generates heat and may reduce durability.

  As shown in FIG. 21, if the offset between the track groove 2 of the outer ring 3 and the track groove 5 of the inner ring 6 is eliminated, the wedge angle does not occur, so that the pushing force as described above does not occur on the ball 7. However, if the offset is eliminated, a force for controlling the cage 8 is not generated, so that the constant velocity universal joint does not operate.

  Even when the track grooves of the inner ring and the outer ring are inclined spirally or axially, a track offset is attached. For this reason, the ball contact force of the track grooves of the inner ring and the outer ring decreases, and the force applied to the cage decreases. However, even in such a constant velocity universal joint, heat is generated due to contact between the inner spherical surface of the cage and the outer spherical surface of the inner ring or contact between the outer spherical surface of the cage and the inner spherical surface of the outer ring when a large load is applied or when the rotational speed is high. , Durability may be reduced.

  In view of the above problems, the present invention suppresses heat generation during high loads and high-speed rotation, improves durability, and stabilizes the cage position, so that the contact resistance between the cage and the inner and outer rings is suppressed, etc. Provided is a constant velocity universal joint with improved speed (decrease in torque loss rate).

  The constant velocity universal joint of the present invention includes an outer joint member in which a plurality of track grooves are formed on an inner spherical surface, and an inner joint member in which a plurality of track grooves that are paired with the track grooves of the outer joint member are formed on an outer spherical surface; A plurality of balls that transmit torque between the track groove of the outer joint member and the track groove of the inner joint member, and the inner spherical surface of the outer joint member and the outer spherical surface of the inner joint member. In the constant velocity universal joint with the cage for holding the ball, the axial offset between the center of curvature of the track groove of the outer joint member and the center of curvature of the inner spherical surface of the outer joint member, and the center of curvature of the track groove of the inner joint member and the inside The axial offset of the center of curvature of the outer spherical surface of the joint member is set to 0, and the track groove of the outer joint member and the track groove of the inner joint member are inclined with respect to the axis line, respectively, and the tr It is reciprocal inclination direction of the click groove, and is the track grooves and the track grooves of the inner joint member opposed to the outer joint member which is inclined in the opposite direction about the axis.

  According to the constant velocity universal joint of the present invention, the track offset is zero and the track grooves adjacent in the circumferential direction alternately intersect. For this reason, the force of the opposite direction acts on the window part of the cage adjacent to the circumferential direction, and a cage is stabilized in a joint center position.

  The number of balls can be 6, 8, or 10.

The center of curvature of the track groove of the outer joint member is radially offset with respect to the center of curvature of the inner spherical surface of the outer joint member, and the center of curvature of the track groove of the inner joint member is offset from the center of curvature of the outer spherical surface of the inner joint member. Further, it may be offset in the radial direction.

  Even if the track groove is a bar field type composed of an arc portion, the track groove may be an undercut free type composed of an arc portion and a straight portion.

  Moreover, the track groove of the outer joint member and the track groove of the inner joint member may be formed by forging skin finishing, or may be formed by cutting and / or grinding. Here, the forged skin finish is a finish in which the forged skin is left as it is, and finishing processing such as grinding is not performed.

  In the constant velocity universal joint of the present invention, a force in the opposite direction acts on the window portion of the cage adjacent in the circumferential direction, and the cage is stabilized at the joint center position. For this reason, contact between the inner spherical surface of the cage and the outer spherical surface of the inner ring, and contact between the outer spherical surface of the cage and the inner spherical surface of the outer ring are suppressed, and this constant velocity universal joint operates smoothly during high loads and high speed rotation, generating heat. It is suppressed and durability is improved.

  The number of balls can be set to 6, 8 or 10, and it can be a bar field type or an undercut free type, and the present invention can be applied to various types of constant velocity universal joints. .

  In addition, when the track groove of the outer joint member and the track groove of the inner joint member are formed by forging skin finishing, it is not necessary to perform finishing processing such as cutting and grinding, and it is possible to improve productivity and reduce cost. . Further, in cutting and grinding, it is possible to take advantage of an optimum finishing process by exchanging the cutting tool and the grinding tool.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2 show the constant velocity universal joint according to the first embodiment, and this constant velocity universal joint is a Barfield (BJ) fixed type constant velocity universal joint. The constant velocity universal joint has an outer ring 13 as an outer joint member in which a plurality of track grooves 12 are formed on the inner spherical surface 11, and a plurality of track grooves 15 that are paired with the track grooves 12 of the outer ring 13 on the outer spherical surface 14. An inner ring 16 as an inner joint member, a plurality of balls 17 interposed between the track grooves 12 of the outer ring 13 and the track grooves 15 of the inner ring 16, and the inner spherical surface 11 of the outer ring 13 and the inner ring 16. And a cage 18 that is interposed between the outer spherical surface 14 and holds the ball 17.

  The axial offset between the center of curvature O1 of the track groove 12 of the outer ring 13 and the center of curvature O2 of the track groove 15 of the inner ring 16 is set to zero. That is, the curvature center O1 and the curvature center O2 are made to coincide with the joint center O.

  As shown in FIGS. 3 to 6, in the outer ring 13, each track groove 12 is inclined with respect to the axial direction. In this case, the inclination directions of the track grooves 12 adjacent to each other in the circumferential direction are contradictory. That is, as shown in FIG. 5, when the track groove 12A is inclined by the angle γ with respect to the axis L in the clockwise direction from the back side toward the opening side, it is adjacent to the track groove 12A in the clockwise direction. The other matching track groove 12B is inclined by γ with respect to the axis L in the counterclockwise direction from the back side toward the opening side. Further, another track groove 12C (see FIG. 3) adjacent to the track groove 12A in the counterclockwise direction is inclined by γ with respect to the axis L in the counterclockwise direction from the back side toward the opening side. Further, as shown in FIG. 6, the center of curvature O1 of the track groove 12 and the center of curvature O5 of the inner spherical surface 11 are made to coincide with each other without being offset.

  Further, as shown in FIGS. 7 to 10, in the inner ring 16, each track groove 15 is inclined with respect to the axial direction. In this case, the inclination directions of the track grooves 15 adjacent to each other in the circumferential direction are contradictory. That is, as shown in FIG. 9, when the track groove 15A is inclined by the angle γ (the same angle as the track groove 12 of the outer ring 13) in the counterclockwise direction from the back side toward the opening side, Another track groove 15B adjacent to the track groove 15A in the clockwise direction is inclined by γ with respect to the axis L in the clockwise direction from the back side toward the opening side. Further, another track groove 15C (see FIG. 7) adjacent to the track groove 15A in the counterclockwise direction is inclined by γ with respect to the axis L in the clockwise direction from the back side toward the opening side. Further, as shown in FIG. 10, the center of curvature O2 of the track groove 15 and the center of curvature O6 of the outer spherical surface 14 are matched without being offset.

  The cage 18 is an annular body as shown in FIGS. 11 and 12, and as shown in FIGS. 11 and 13, a plurality of window portions 19 in which the balls 17 are accommodated in the circumferential wall are provided along the circumferential direction. It is arranged. As shown in FIG. 13, the center of curvature O7 of the outer spherical surface 18a and the center of curvature O8 of the inner spherical surface 18b are made to coincide.

  Incidentally, the track grooves 12 of the outer ring 13 and the track grooves 15 of the inner ring 16 are formed by forging skin finishing. Here, the forged skin finish means that the track groove 12 and the track groove 15 are formed with a forged finish hardened layer. For example, steel containing 0.4 wt% or more of carbon is used for the outer ring 13, and the track grooves 12 of the outer ring 13 are formed by forging (cold forging), and then heat treatment is performed on the entire inner circumference of the outer ring 13. Will do. For this reason, a forged finishing hardened layer is formed on at least the groove surfaces of the track grooves 15 and 12 of the inner ring 16 and outer ring 13. That is, the forged finish hardened layer is a surface layer that leaves the forged skin as it is, and is a layer that is not subjected to finishing such as grinding. The track groove 15 of the inner ring 16 is also formed by forging skin finishing by the same processing as the track groove 12 of the outer ring 13.

The outer ring 13, the inner ring 16 and the cage 18 configured as described above are assembled as shown in FIGS. In this case, the track groove 12 of the outer ring 13 and the corresponding track groove 15 of the inner ring 16 are inclined in opposite directions with respect to the axis.

  The ball contact point A of the track groove 12 of the outer ring 13 and the ball contact point B of the track groove 15 of the inner ring 16 corresponding to the track groove 12 are shifted to the back side by e from the ball center line L1. Therefore, the angle formed by the tangent line of the ball contact point A and the tangent line of the ball contact point B is the wedge angle τ ′.

  Accordingly, in this constant velocity universal joint, there is no offset of the track grooves 12 and 15 in the axial direction, but a wedge angle is generated because the track grooves 12 and 15 are inclined at a predetermined angle with respect to the axis. For this reason, a pushing force W is generated in the cage. However, since the track grooves adjacent in the circumferential direction intersect, this pushing force W acts in the opposite direction in the tracks adjacent in the circumferential direction. For this reason, the cage position is stable at the joint center.

  In the constant velocity universal joint of the present invention, the axial offset between the center of curvature O1 of the track groove 12 of the outer ring 13 and the center of curvature O5 of the inner spherical surface 11 of the outer ring 13, the center of curvature O2 of the track groove 15 of the inner ring 16 and the inner ring 16 is obtained. The offset in the axial direction of the center of curvature O6 of the outer spherical surface 14 is 0, the offset in the axial direction between the center of curvature O1 of the track groove 12 of the outer ring 13 and the center of curvature O2 of the track groove 15 of the inner ring 16 is 0, and Since the track grooves 12A, 12B (15A, 15B) adjacent to each other in the circumferential direction cross alternately, a force in the opposite direction acts on the window portion 19 adjacent in the circumferential direction of the cage 18, and the cage 18 is connected to the joint. Stable at the center O position. For this reason, the contact between the cage inner spherical surface 18b and the outer spherical surface 14 of the inner ring 16 and the contact between the cage outer spherical surface 18a and the inner spherical surface 11 of the outer ring 13 are suppressed, and the constant velocity universal joint is smooth during high loads and high speed rotations. The heat generation is suppressed and the durability is improved. Even when a track offset is added and adjacent tracks are crossed, a constant velocity universal joint is established, but the ball 7 always receives force on the opening side. However, contact between the cage inner spherical surface 8b and the outer spherical surface 4 of the inner ring 6 and contact between the cage outer spherical surface 8a and the inner spherical surface 1 of the outer ring 3 may generate heat, which may reduce durability.

  By the way, the number of balls 17 as the torque transmitting member may be six, eight, or ten. If the number of balls 17 is increased, the diameter of the balls is reduced. Therefore, it is possible to suppress a decrease in load capacity per unit, and to achieve high performance and compactness.

  In the above embodiment, the track grooves 12 of the outer ring 13 and the track grooves 15 of the inner ring 16 are formed by finishing the forged surface, so that it is not necessary to perform finishing processing such as cutting and grinding, thereby improving productivity. Cost reduction can be achieved.

  In contrast, the track groove 12 of the outer ring 13 and the track groove 15 of the inner ring 16 may be subjected to finishing such as cutting or grinding. In cutting and grinding, it is possible to take advantage of an optimum finishing process by exchanging the cutting tool and the grinding tool.

  The constant velocity universal joint of the above embodiment is a bar field type in which the track grooves 12 and 15 are formed by arc portions, but the track grooves 12 and 15 are undercut free types having an arc portion and a straight portion. There may be.

  Even in this undercut free type, the axial offset between the center of curvature of the track groove of the outer ring and the center of curvature of the track groove of the inner ring is set to zero. In addition, the track groove of the outer ring and the track groove of the inner ring are inclined with respect to the axis, respectively, and the inclination directions of the track grooves adjacent to each other in the circumferential direction are made opposite to each other. Further, the track groove of the outer ring and the track groove of the inner ring opposed thereto are inclined in the opposite direction with respect to the axis.

  For this reason, even an undercut-free type constant velocity universal joint has the same effects as the Barfield type constant velocity universal joint shown in FIG.

  In the embodiment, the curvature center O1 of the track groove 12 and the curvature center O5 of the inner spherical surface 11 are matched without being offset in the radial direction, and the curvature center O2 of the track groove 15 and the curvature center of the outer spherical surface 14 are matched. It is matched with O6 without being offset in the radial direction. On the other hand, the curvature center O1 of the track groove 12 and the curvature center O5 of the inner spherical surface 11 are offset in the radial direction, and the curvature center O2 of the track groove 15 and the curvature center O6 of the outer spherical surface 14 are radial. May be offset.

  By offsetting in the radial direction in this manner, the groove depth of the track grooves 12 and 15 can be changed. For this reason, it can be set as the structure which can prevent the ball | bowl 17 from detaching from the track grooves 12 and 15, or the structure which can aim at the rigidity improvement etc. of the outer ring | wheel 13 and the inner ring | wheel 16.

  As described above, the embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, as the inclination angle γ of the track grooves 12 and 15, the adjacent balls The pushing force acting on the ball 17 arranged on the track acts in the opposite direction, and various changes can be made within a range that does not hinder the operation of the constant velocity universal joint.

It is sectional drawing of the constant velocity universal joint which shows 1st Embodiment of this invention. It is a front view of the said constant velocity universal joint. It is a perspective view of the outer ring | wheel of the said constant velocity universal joint. It is a front view of the outer ring | wheel of the said constant velocity universal joint. It is sectional drawing of the outer ring | wheel of the said constant velocity universal joint. It is principal part sectional drawing of the outer ring | wheel of the said constant velocity universal joint. It is a perspective view of the inner ring | wheel of the said constant velocity universal joint. It is a front view of the inner ring | wheel of the said constant velocity universal joint. It is a side view of the inner ring | wheel of the said constant velocity universal joint. It is principal part sectional drawing of the outer ring | wheel of the said constant velocity universal joint. It is a perspective view of the cage of the constant velocity universal joint. It is a front view of the cage of the constant velocity universal joint. It is sectional drawing of the cage of the said constant velocity universal joint. It is operation | movement explanatory drawing of the said constant velocity universal joint. It is a simplified development view of the constant velocity universal joint. It is sectional drawing of the conventional constant velocity universal joint. It is a front view of the constant velocity universal joint shown in the said FIG. It is sectional drawing of the other conventional constant velocity universal joint. It is a front view of the constant velocity universal joint shown in the said FIG. It is sectional drawing explaining the problem of the conventional constant velocity universal joint. It is sectional drawing explaining the other problem of the conventional constant velocity universal joint. It is sectional drawing of the conventional constant velocity universal joint.

Explanation of symbols

11 Inner spherical surface 12, 15 Track groove 14 Outer spherical surface 17 Ball 18 Cage O Joint center O1 Center of curvature O2 Center of curvature

Claims (9)

An outer joint member in which a plurality of track grooves are formed on the inner spherical surface, an inner joint member in which a plurality of track grooves that are paired with the track grooves of the outer joint member are formed on the outer spherical surface, and the track grooves and the inner side of the outer joint member A plurality of balls that transmit torque by being interposed between the track grooves of the joint member, and a cage that holds the balls by being interposed between the inner spherical surface of the outer joint member and the outer spherical surface of the inner joint member. In constant velocity universal joints,
An axial offset between the center of curvature of the track groove of the outer joint member and the center of curvature of the inner spherical surface of the outer joint member, and an axial offset of the center of curvature of the track groove of the inner joint member and the center of curvature of the outer spherical surface of the inner joint member And the track groove of the outer joint member and the track groove of the inner joint member are inclined with respect to the axis, and the inclination directions of the track grooves adjacent to each other in the circumferential direction are opposite to each other. A constant velocity universal joint characterized in that the track groove of the inner joint member facing this is inclined in the opposite direction with respect to the axis.   The constant velocity universal joint according to claim 1, wherein the number of balls is six.   The constant velocity universal joint according to claim 1, wherein the number of balls is eight.   The constant velocity universal joint according to claim 1, wherein the number of balls is ten.   The center of curvature of the track groove of the outer joint member is radially offset with respect to the center of curvature of the inner spherical surface of the outer joint member, and the center of curvature of the track groove of the inner joint member is relative to the center of curvature of the outer spherical surface of the inner joint member. The constant velocity universal joint according to any one of claims 1 to 4, wherein the constant velocity universal joint is offset in a radial direction.   The constant velocity universal joint according to any one of claims 1 to 5, wherein the track groove is a bar field type constituted by an arc portion.   The constant velocity universal joint according to any one of claims 1 to 5, wherein the track groove is an undercut free type composed of an arc portion and a straight portion.   The constant velocity universal joint according to claim 1, wherein the track groove of the outer joint member and the track groove of the inner joint member are formed by forging skin finishing.   The constant velocity universal joint according to claim 1, wherein the track groove of the outer joint member and the track groove of the inner joint member are formed by cutting and / or grinding.

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