JP2009085326A - Constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a constant velocity universal joint capable of keeping operability and improving its strength at high-angle. <P>SOLUTION: A first ball track 31 is structured with a first external track groove 21a of an external joint member and a first internal track groove 23a of an internal joint member. A second ball track 32 is structured with a second external track groove 21b of the external joint member and a second internal track groove 23b of the internal joint member. In the tracks 31, 32, the center of curvature of the track grooves 21a, 21b of the external joint member and the center of curvature of the track grooves 23a, 23b of the internal joint member are offset to the center of the joint. When an offset amount of the track 31 is represented as F<SB>A</SB>and that of the track 32 as F<SB>B</SB>, 0≤F<SB>B</SB><F<SB>A</SB>is satisfied. The center of curvature of the outer spherical surface 18a of a case 18 and center of curvature of the inner spherical surface 18b of the case 18 are offset reversely in the axial direction by an equal distance to the center of the joint. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a constant velocity universal joint used, for example, in a power transmission system of an automobile or various industrial machines.

  For example, there is a fixed type constant velocity universal joint as a kind of constant velocity universal joint used as means for transmitting rotational force from an engine of an automobile to wheels at a constant speed. This fixed type constant velocity universal joint has a structure in which two shafts on the driving side and the driven side are connected and the rotational torque can be transmitted at a constant speed even if the two shafts have an operating angle. Generally, as the above-described constant velocity universal joint, a bar field type (BJ) and an undercut free type (UJ) are widely known.

  For example, a BJ type constant velocity universal joint includes an outer ring 3 as an outer member in which a plurality of track grooves 2 are formed in the inner spherical surface 1 at equal intervals in the circumferential direction as shown in FIG. An inner ring 6 as an inner 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, and the track grooves 2 of the outer ring 3 A plurality of balls 7 that are interposed between the track grooves 5 of the inner ring 6 and transmit torque, and a cage 8 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 and holds the balls 7. And. The cage 8 is provided with a plurality of pockets 9 for accommodating the balls 7 along the circumferential direction.

  The center of curvature Oa of the track groove 5 of the inner ring 6 and the center of curvature Ob of the track groove 2 of the outer ring 3 are offset in the axial direction opposite to the joint center O by an equal distance F, F (track offset). By offsetting in this way, a wedge angle is formed in the track grooves 5 and 2 between the inner ring 6 and the outer ring 3 (an angle at which the track grooves 5 and 2 of the inner and outer rings sandwich the ball 7), and the ball 7 is It becomes possible to stably position on the equal surface.

  However, when a track offset is added, the ball track (comprised of the track groove 5 of the inner ring 6 and the track groove 2 of the outer ring 3) becomes shallower at the end by the amount of the track offset. Becomes shallow at the back of the track. In this way, when the ball track is shallow on the back side of the track, when the joint (joint) takes a large angle (operation angle), the ball is positioned in the shallow portion of the track. At this time, if a large torque is applied, the ball rides on the track. For this reason, the strength at high angles is dominated by the depth of the track grooves.

  However, if the track offset amount is reduced, the depth of the track groove can be ensured (= advantageous for strength at high angles), but the wedge angle becomes small and the operability deteriorates. That is, the force with which the track groove 5 of the inner ring 6 and the track groove 2 of the outer ring 3 restrain the ball becomes small, and it becomes easy to be caught when bent. Therefore, it is necessary to determine the track offset amount so that the balance between the track groove depth and the wedge angle is balanced.

Therefore, conventionally, as a means for solving the above problem, there is a method of alternately applying different track offset amounts (Patent Document 1). Also, as means for compensating for the lack of the track groove depth on the back side of the track at high angles, the track groove is secured by combining a curve and a straight line (Patent Document 2), contact There are those in which the value is changed from the track entrance side to the back side (Patent Document 3), and the contact rate is changed from the track entrance side to the back side (Patent Document 4).
Japanese Patent No. 3475484 JP 2004-156699 A Reality 8-3712 Shoko Sho 64-6412

  In the device disclosed in Patent Document 1, the wedge angle is small in a track having a small track offset, but the operability can be ensured because the wedge angle is large in a track having a large track offset. However, the operability may be poor depending on the number of balls and the arrangement of two types of track offsets. That is, when four small ball tracks with zero or a slight offset amount are arranged in a 90 ° pitch with eight balls, the operability when the shaft is bent toward the track with a small track offset is deteriorated.

  Also, as described in Patent Document 2, the track groove is combined with a curve and a straight line to ensure the depth of the track groove, or as described in Patent Document 3, the contact angle is set from the track entrance side to the back side. When the contact ratio is changed or the value of the contact ratio is changed from the track entrance side to the back side as described in Patent Document 4, a plurality of track shapes are formed in one track, and thus a high manufacturing technique is required. Become.

  In view of the above problems, the present invention provides a constant velocity universal joint capable of maintaining operability and improving strength at high angles.

The constant velocity universal joint of the present invention includes an outer joint member in which the first outer track groove and the second outer track groove are alternately arranged at a predetermined pitch along the circumferential direction, the first inner track groove and the second inner track groove. Inner joint members arranged alternately at a predetermined pitch along the circumferential direction, first joint track grooves of the outer joint member, and first inner track grooves of the inner joint member corresponding thereto are formed. Rolling a second ball track composed of a first ball that rolls in the first ball track, a second outer track groove of the outer joint member, and a second inner track groove of the inner joint member corresponding thereto. A constant velocity universal joint comprising a second ball and a cage for holding the first ball and the second ball interposed between an outer joint member and an inner joint member. Joint member track The center of curvature of the track grooves of the center of curvature and the inner joint member, causes offset in opposite directions by axial equidistant relative to the joint center, the offset amount of the first ball tracks and F _A, the second ball tracks When the offset amount of FB is F _B , 0 ≦ F _B <F _A , and the center of curvature of the outer spherical surface of the cage and the center of curvature of the inner spherical surface of the cage are axially spaced by an equal distance from the joint center. Is offset in the opposite direction.

  In the constant velocity universal joint of the present invention, the offset amount of the first ball track is set larger than the offset amount of the second ball track. For this reason, in a track with a small track offset amount (second ball track), the depth of the track groove on the back side of the track can be secured for both the outer ring (outer joint member) and the inner ring (inner joint member).

  Further, regarding the wall thickness on the joint opening side of the outer ring, the first ball track side is thin and the second ball track side is thick. Further, since the wedge angle of the second ball track is reduced, the frictional force between the ball tracks is reduced and the amount of heat generation is reduced.

  By the way, when the track offset amount is small, the depth of the groove can be secured. However, for example, when the first ball and the second ball are alternately arranged at a 45 ° pitch, a track having a small track offset at a 90 ° pitch can be obtained. It will be placed and its operability will deteriorate. Therefore, in the present invention, the operation is performed by ensuring the wedge angle by offsetting the center of curvature of the outer spherical surface of the cage and the center of curvature of the inner spherical surface of the cage by an equal distance from the joint center in the axial direction. Can improve sex.

  The total number of torque transmitting balls may be four, that is, four of the first ball and four of the second ball. Further, in each ball track, even if the track groove of the outer joint member and the groove groove of the inner joint member have a straight portion, the groove bottom of the center of curvature is different from the groove bottom of the offset arc portion. The taper part which inclines toward the outer diameter side from the joint back part to the joint opening part in the groove bottom of the track groove of the outer joint member and the track groove of the inner joint member, even if it has a circular arc part of It may be. Furthermore, the center of curvature of the track groove of the outer joint member and the center of curvature of the track groove of the inner joint member may be offset in the radial direction from the joint axis.

  The predetermined pitch as the arrangement pitch of the track grooves may be an equal pitch or an unequal pitch. If the track grooves are arranged at unequal pitches in the circumferential direction, the cage pockets are also arranged at unequal pitches in the circumferential direction. For this reason, a long pocket with a large circumferential interval is formed. Accordingly, the pocket having a large circumferential length can be used, and when the inner ring is assembled into the cage, the pocket having a large circumferential length can be used during the assembly.

  It can be used for a propeller shaft of an automobile and can be used for a drive shaft of an automobile.

  In the present invention, in a track with a small track offset amount (second ball track), the depth of the track groove on the back side of the track can be ensured for both the outer ring (outer joint member) and the inner ring (inner joint member). For this reason, even when a large torque is applied in a state where the ball is positioned on the back side of the track, it is possible to avoid the ball from climbing up. In addition, since the wedge angle of the second ball track is small, the frictional force between the ball tracks is small, and the heat generation amount is reduced. That is, since transmission efficiency increases, it is more advantageous than conventional products in terms of fuel efficiency when mounted on a vehicle. Moreover, since the track shape of the ball track is relatively simple, this constant velocity universal joint can be manufactured at a low cost without requiring a high manufacturing technique.

  By using eight balls, the load acting on each ball is smaller compared to the number of balls less than that, so the allowable load torque is large, and if the allowable load torque is the same, the size can be reduced. Can do.

  By adopting an undercut free type in which the track groove bottom includes an arc portion and a straight portion, the joint operating angle can be increased. Further, if the track groove bottom has an arc portion and a taper portion, the angle can be further increased.

  The track groove has a plurality of circular arcs at the bottom of the track groove, or the center of curvature of the track groove of the outer joint member and the center of curvature of the track groove of the inner joint member are offset in the radial direction from the joint axis, respectively. The joint back side can be deepened, or the joint opening side of the track groove can be deepened. For this reason, the relationship between the depth of the track groove related to the strength at high angles and the wedge angle related to the operability of the joint can be more optimally balanced. That is, it is possible to more stably realize a joint that maintains operability and also improves strength at high angles.

  If the arrangement pitch of the track grooves is equal, the balance is excellent. Further, if the track grooves of the inner member and the track grooves of the outer member are arranged at unequal pitches in the circumferential direction, the cage pockets are also arranged at unequal pitches in the circumferential direction. As a result, when the inner ring is assembled in the cage, a pocket having a large circumferential length can be used during the assembly, and the assemblability can be improved.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the constant velocity universal joint includes an outer ring 13 as an outer joint member, an inner ring 16 as an inner joint member disposed inside the outer ring 13, and an outer ring 13 and an inner ring 16. Thus, a plurality of balls 17a and 17b (see FIG. 5) that transmit torque and a cage 18 that is interposed between the outer ring 13 and the inner ring 16 and holds the balls 17a and 17b are configured as main members. The inner ring 16 is spline-fitted by press-fitting an end of a shaft (not shown) into the inner diameter of the hole, and is coupled to the shaft so that torque can be transmitted.

  As shown in FIG. 5, the outer ring 13 has a first outer track groove 21a and a second outer track groove 21b on the inner spherical surface 20 at a predetermined pitch (in this case, a constant pitch of 45 °) along the circumferential direction. The four are alternately arranged. The inner ring 16 has alternately arranged first inner track grooves 23a and second inner track grooves 23b on the outer spherical surface 22 at a predetermined pitch (in this case, a constant pitch of 45 °) along the circumferential direction. .

As shown in FIG. 2, the center of curvature O1 of the first outer track groove 21a of the outer ring 13 is offset from the plane including the joint center O in the axial direction by F _{A in the} axial direction. Also the center of curvature O2 of the second outer track grooves 21b of the outer ring 13 is offset F _B in the axial direction to the joint opening side with respect to a plane containing the joint center O. In this case, although F _B <F _A , the center of curvature O2 of the second outer track groove 21b may not be offset. For this reason, 0 ≦ F _B <F _A. The radius of curvature RoA of the first outer track groove 21a is the radius of curvature RoB of the second outer track groove 21b.

As shown in FIG. 3, the curvature center O3 of the first inner track groove 23a of the inner ring 16 is offset from the plane including the joint center O in the axial direction by F _A toward the joint back side. Further, the center of curvature O4 of the second inner track grooves 23b of the inner ring 16, and only by an offset F _B to the joint opening side in the axial direction with respect to the plane including the joint center O. The radius of curvature RiA of the first inner track groove 23a and the radius of curvature RiB of the second inner track groove 23b.

That is, the constant velocity universal joint includes a first ball track 31 composed of a first outer track groove 21 a of the outer ring 13 and a corresponding first inner track groove 23 a of the inner ring 16, and a second outer side of the outer ring 13. A second ball track 32 constituted by the track groove 21b and the second inner track groove 23b of the inner ring 16 corresponding thereto is formed. Therefore, the offset amount of the first ball track 31 is F _A , the offset amount of the second ball track is F _B , and 0 ≦ F _B <F _A.

  Therefore, as shown in FIG. 2, when the depth of the back side of the first outer track groove 21a is H1, and the depth of the back side of the second outer track groove 21b is H2, H1 <H2. Become. Further, when the thickness on the opening side of the first outer track groove 21a is t1, and the thickness on the opening side of the second outer track groove 21b is t2, t1 <t2.

  Further, as shown in FIG. 4, the center of curvature O5 of the outer spherical surface 18a of the cage 18 and the center of curvature O6 of the inner spherical surface 18b of the cage 18 are offset by an equal distance c in the axial direction with respect to the plane including the joint center O. I am letting. The radius of curvature of the outer spherical surface 18a of the cage 18 is RoC, and the radius of curvature of the inner spherical surface 18b of the cage 18 is RiC.

  In the present invention, the offset amount of the first ball track 31 is set larger than the offset amount of the second ball track 32. For this reason, in a track having a small track offset amount (second ball track), both the outer ring 13 and the inner ring 16 can secure the depth of the track groove on the back side of the track. That is, even when a large torque is applied in a state where the ball 17b is located on the back side of the track, the riding of the ball 17b can be avoided, and the wall thickness on the joint opening side of the outer ring 13 is the first ball track. The side is thin and the second ball track side is thick. Since the wedge angle of the second ball track 32 is small, the frictional force between the ball tracks is small, and the heat generation amount is reduced. That is, since transmission efficiency increases, it is more advantageous than conventional products in terms of fuel efficiency when mounted on a vehicle. Moreover, since the track shapes of the ball tracks 31 and 32 are relatively simple, this constant velocity universal joint can be manufactured at a low cost without requiring a high manufacturing technique.

  By the way, when the track offset amount is small, the depth of the groove can be secured. However, when the first balls 17a and the second balls 17b are alternately arranged at a 45 ° pitch, a track with a small track offset at a 90 ° pitch can be obtained. It will be placed and its operability will deteriorate. Therefore, in the present invention, the wedge angle is set by offsetting the center of curvature of the outer spherical surface 18a of the cage 18 and the center of curvature of the inner spherical surface 18b of the cage 18 in the axial direction opposite to the joint center O by an equal distance. By ensuring, operability can be improved.

  By setting the number of balls 17a, 17b to eight, the load acting on each ball 17a, 17b is small compared to the number of balls less than that, so that the allowable load torque is large and the allowable load torque is the same. Miniaturization can be achieved.

  In the constant velocity universal joint shown in FIG. 6, in each of the ball tracks 31, 32, the centers of curvature O1, O2 of the track grooves 21a, 21b of the outer ring 13 and the centers of curvature O3, O4 of the track grooves 23a, 23b of the inner ring 16 are respectively jointed. They are offset by δ1 and δ2 in the radial direction from the axis. Note that δ1 = δ2.

  In this way, the center of curvature O1, O2 of the track grooves 21a, 21b of the outer ring 13 and the center of curvature O3, O4 of the track grooves 23a, 23b of the inner ring 16 are offset in the radial direction from the joint axis, respectively. The joint back side can be deepened, or the joint opening side of the track groove can be deepened. For this reason, the relationship between the depth of the track groove related to the strength at high angles and the wedge angle related to the operability of the joint can be more optimally balanced. That is, it is possible to more stably realize a joint that maintains operability and also improves strength at high angles.

  FIG. 7 shows an undercut-free type in which the track groove bottom includes an arc portion and a straight portion. That is, the track grooves 21a and 21b of the outer ring 13 are formed by arcuate portions 41a and 41b on the back side and straight portions 42a and 42b on the opening side, respectively. Further, the track grooves 23a, 23b of the inner ring 16 of the inner ring 16 are respectively composed of straight portions 43a, 43b on the back side and arc portions 44a, 44b on the opening side.

Also in this case, the offset amount of the first ball track 31 is F _A , the offset amount of the second ball track 32 is F _B , and 0 ≦ F _B <F _A. Further, the center of curvature O5 of the outer spherical surface 18a of the cage 18 and the center of curvature O6 of the inner spherical surface 18b of the cage 18 are offset by an equal distance c in the axial direction with respect to the plane including the joint center O.

  For this reason, even if it is a constant velocity universal joint shown in FIG. 7, the same effect as the constant velocity universal joint shown in the said FIG. 1 etc. can be show | played. In addition, the joint operating angle can be increased.

  Next, in the constant velocity universal joint shown in FIG. 8, the track groove bottoms of the inner ring 16 and the outer ring 13 are provided with an arc portion and a tapered portion. That is, the track grooves 21a and 21b of the outer ring 13 are formed by arcuate portions 51a and 51b on the back side and tapered portions 52a and 52b on the opening side, respectively. Further, the track grooves 23a and 23b of the inner ring 16 of the inner ring 16 are respectively composed of inner tapered portions 53a and 53b and opening-side arc portions 54a and 54b. The tapered parts 52a and 52b of the outer ring 13 are inclined toward the outer diameter side from the joint back part toward the joint opening. The track grooves 23a and 23b of the inner ring 16 are inclined toward the outer diameter side from the joint opening part side toward the joint back part.

Also in this case, the offset amount of the first ball track 31 is F _A , the offset amount of the second ball track is F _B , and 0 ≦ F _B <F _A. Further, the center of curvature O5 of the outer spherical surface 18a of the cage 18 and the center of curvature O6 of the inner spherical surface 18b of the cage 18 are offset by an equal distance c in the axial direction with respect to the plane including the joint center O.

  For this reason, even if it is a constant velocity universal joint shown in FIG. 8, there can exist an effect similar to the constant velocity universal joint shown in the said FIG. In addition, the angle can be further increased than that shown in FIG.

  In each ball track 31, 32, the track grooves 21 a, 21 b of the outer ring 13 and the track grooves 23 a, 23 b of the inner ring 16 are curved arc portions of the groove bottom at the center of curvature O different from the track groove bottom of the offset arc portion. It may have.

  By having a plurality of arc portions at the bottom of the track groove, it is possible to deepen the joint back side of the track groove or deepen the joint opening side of the track groove. For this reason, the relationship between the depth of the track groove related to the strength at high angles and the wedge angle related to the operability of the joint can be more optimally balanced. That is, it is possible to more stably realize a joint that maintains operability and also improves strength at high angles.

  In the above-described embodiment, the arrangement pitch of the track grooves is the same pitch, but may be an unequal pitch. If the pitch is equal, the balance is excellent. Further, if the track grooves are arranged at unequal pitches in the circumferential direction, the cage pockets are also arranged at unequal pitches in the circumferential direction. For this reason, a long pocket with a large circumferential interval is formed. As a result, the pocket having a large circumferential length can be used, and when the inner ring is assembled into the cage, the pocket having the large circumferential length can be used during the assembly, thereby improving the assemblability. be able to.

  As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the curvature centers O1, O2, O3, O4, O5, and O6 The offset amount can be arbitrarily changed as long as the operability is maintained and the strength at high angles can be improved. Further, the number of balls 17 is not limited to eight, and may be six or four less than eight, or may be ten or twelve more than eight.

It is a longitudinal cross-sectional view of the constant velocity universal joint which shows embodiment of this invention. It is a longitudinal cross-sectional view of the outer ring | wheel of the said constant velocity universal joint. It is a longitudinal cross-sectional view of the inner ring | wheel of the said constant velocity universal joint. It is a longitudinal cross-sectional view of the cage of the constant velocity universal joint. It is a principal part cross-sectional view of the said constant velocity universal joint. It is a longitudinal cross-sectional view of the constant velocity universal joint which shows other embodiment of this invention. It is a longitudinal cross-sectional view of the constant velocity universal joint which shows another embodiment of this invention. It is a longitudinal cross-sectional view of the constant velocity universal joint which shows another embodiment of this invention. It is a longitudinal cross-sectional view of the conventional constant velocity universal joint.

Explanation of symbols

17a, 17b Ball 18 Cage 18a Outer spherical surface 18b Inner spherical surface 21a First outer track groove 21b Second outer track groove 23a First inner track groove 23b Second inner track groove 31, 32 Ball tracks 41a, 41b Arc portions 42a, 42b Straight Portions 43a, 43b straight portions 44a, 44b arc portions 51a, 51b arc portions 52a, 52b taper portions 53a, 53b taper portions 54a, 54b arc portions 19 cage pocket

Claims (10)

An outer joint member in which the first outer track groove and the second outer track groove are alternately arranged at a predetermined pitch along the circumferential direction, and the first inner track groove and the second inner track groove along the circumferential direction. Rolls in a first ball track composed of inner joint members alternately arranged at a predetermined pitch, first outer track grooves of the outer joint members, and first inner track grooves of the corresponding inner joint members. A second ball that rolls on a second ball track composed of a first ball to be moved, a second outer track groove of the outer joint member, and a second inner track groove of the inner joint member corresponding thereto, and the outer joint member And a constant velocity universal joint provided with a cage for holding the first ball and the second ball interposed between the inner joint member and the inner joint member,
In each ball track, the center of curvature of the track groove of the outer joint member and the center of curvature of the track groove of the inner joint member are offset in the axial direction opposite to each other by an equal distance from the joint center. When the offset amount is F _A and the offset amount of the second ball track is F _B , 0 ≦ F _B <F _A and the center of curvature of the outer spherical surface of the cage and the center of curvature of the inner spherical surface of the cage are A constant velocity universal joint that is offset in the axial direction by an equal distance from the joint center.   2. The constant velocity universal joint according to claim 1, wherein the total number of torque transmitting balls is eight including four of the first balls and four of the second balls.   3. The constant velocity universal joint according to claim 1, wherein each ball track has a straight portion at a groove bottom of a track groove of the outer joint member and a track groove of the inner joint member.   The track groove of the outer joint member and the track groove of the inner joint member in each ball track have a curved arc portion of the groove center at the center of curvature different from the groove bottom of the offset arc portion. The constant velocity universal joint according to claim 1.   Each ball track is provided with a taper portion that is inclined from the inner part of the joint toward the outer diameter side toward the joint opening at the bottom of the track groove of the outer joint member, and at the bottom of the track groove of the inner joint member. The constant velocity universal joint according to claim 1, further comprising a tapered portion that inclines toward the outer diameter side from the side toward the joint back portion.   6. In each of the ball tracks, the center of curvature of the track groove of the outer joint member and the center of curvature of the track groove of the inner joint member are offset in the radial direction from the joint axis, respectively. The constant velocity universal joint described in Crab.   The constant velocity universal joint according to any one of claims 1 to 6, wherein the predetermined pitch as an arrangement pitch of the track grooves is an equal pitch.   The constant velocity universal joint according to any one of claims 1 to 6, wherein the predetermined pitch as an arrangement pitch of the track grooves is an unequal pitch.   The constant velocity universal joint according to any one of claims 1 to 8, wherein the constant velocity universal joint is used for a propeller shaft of an automobile.   The constant velocity universal joint according to any one of claims 1 to 8, wherein the constant velocity universal joint is used for a drive shaft of an automobile.

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