JP5138423B2 - Fixed constant velocity universal joint - Google Patents

Description

  The present invention relates to a fixed type constant velocity universal joint and a method of manufacturing the same, and more particularly, is used in a power transmission system of an automobile or various industrial machines, and only allows angular displacement between two axes of a driving side and a driven side. The present invention relates to a fixed type constant velocity universal joint.

  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. In general, as the above-mentioned fixed type constant velocity universal joint, a Barfield type (BJ) and an undercut free type (UJ) are widely known.

  For example, the UJ type fixed type constant velocity universal joint includes an outer ring 3 as an outer member in which a plurality of track grooves 2 are formed on the inner spherical surface 1 as shown in FIGS. Torque is transmitted between the inner ring 6 as an inner member in which a plurality of track grooves 5 paired with the track grooves 2 are formed, and between the track grooves 2 of the outer ring 3 and the track grooves 5 of the inner ring 6. A plurality of balls 7 and a cage 8 that holds the balls 7 interposed between the inner spherical surface 1 of the outer ring 3 and the outer spherical surface 4 of the inner ring 6 are provided. The cage 8 is provided with a plurality of pockets 9 for accommodating the balls 7 along the circumferential direction.

  The track groove 2 of the outer ring 3 includes a back-side track groove 2a in which the track groove bottom is an arc portion and an opening-side track groove 2b in which the track groove bottom is a straight portion parallel to the outer ring axis. The back side track groove 2a has its center of curvature O1 shifted from the joint center O in the axial direction toward the opening side of the outer ring 3. The track groove 5 of the inner ring 6 includes a back side track groove 5a in which the track groove bottom is a straight portion parallel to the inner ring axis, and an opening side track groove 5b in which the track groove bottom is an arc portion. The center of curvature O2 of the opening side track groove 5b is provided at an equal distance k away from the joint center O in the axial direction on the back side opposite to the center of curvature O1 of the back side track groove 2a of the outer ring 3.

  Further, the cage outer spherical surface 8a shifts its radius of curvature O3 from the joint center O in the axial direction toward the opening side of the cage 8, and the cage inner spherical surface 8b has its curvature center O4 moved from the joint center O in the axial direction to the cage outer spherical surface 8a. Is provided on the far side opposite to the center of curvature O3 by an equal distance k1. In this type of conventional constant velocity universal joint, the track offset amount of the inner and outer rings is increased, and the offset amount of the cage is decreased. The pitch angle between two adjacent balls 7 is 60 degrees. That is, six balls 7 are arranged at a pitch of 60 degrees along the circumferential direction.

  By the way, in recent years, it has been demanded that the fixed type constant velocity universal joint can be reduced in size and the torque load capacity can be increased. As a method for reducing the size of the fixed type constant velocity universal joint having six balls and increasing the torque load capacity, it is conceivable to place the largest possible ball on the smallest possible PCD. However, when a large ball is used, the column (window column) between the pockets of the cage becomes thin, and the rigidity of the cage decreases. In particular, for a torsional torque load at a high angle, the cage is easily damaged, which causes a decrease in strength of the constant velocity universal joint.

  In particular, when the track offset amount of the inner and outer rings is large and the offset amount of the cage is small, the track groove depth on the rear side of the outer ring becomes shallow, and the torque load capacity at high angles becomes small. That is, the ball tends to ride on the track edge with respect to a torque load at a high angle, and an excessive stress is generated at the edge portion. For this reason, damage due to chipping of the edge portion or a locking phenomenon with the cage due to plastic deformation occurs. These damages and lock phenomena deteriorate the operability, reduce the durability life, and cause the cage to break. In addition, the inner ring has a shallower track depth on the back side, and has the same drawbacks as the outer ring. For this reason, improvement of joint strength and durability in a high angle region is a conventional problem.

Therefore, as shown in FIGS. 19, 20, 21, and 22, the offset amount of the cage is increased so that the offset amount of the track groove is substantially the same, and the depth of the track groove on the rear side of the outer ring is increased. The torque load capacity at high angles is increased, the pockets 9 of the cage 8 are provided in four places as a whole, and the long pockets 9 (9a) and the short pockets 9 (9b) are respectively provided at positions opposite to each other on the circumference. There are two places where two balls 7 are arranged in the long pocket 9a and one ball 7 is arranged in the short pocket 9b (Patent Document 1). As a result, a large ball can be arranged on a small PCD, and the size can be reduced without reducing the load capacity.
JP 2007-263163 A

  However, in the constant velocity universal joint as shown in FIGS. 19 and 20, as shown in FIG. 23, when rotating with a large operating angle θ, the long pocket 9a of the cage 8 containing the two balls 7 is accommodated. Among the long sides facing each other, the phenomenon that the opening-side edge portion 11 gets over the spherical inner diameter inlet edge portion 10 of the outer ring 3 is repeated.

  In particular, when the load torque and the operating angle are large, interference between the long opening side edge portion 11 facing the long pocket 9a of the cage 8 and the spherical inner diameter inlet edge portion 10 of the outer ring 3 is likely to occur. For this reason, it is difficult for lubricant such as grease to intervene in this portion, and as shown in FIG. 24, damage due to surface peeling or the like in the vicinity of the opening-side edge portion 11 of the long side facing the long pocket 9a of the cage 8 occurs. There is a problem that the portion 12 is likely to occur.

  In view of the above-described problems, the present invention can suppress peeling and the like that are likely to occur on the opening side spherical surface portion of the cage pocket, can improve durability, and can also improve assemblability. Provide fittings.

The first fixed type constant velocity universal joint according to the present invention includes an outer member having a plurality of track grooves formed on an inner spherical surface, an inner member having a plurality of track grooves formed on the outer spherical surface, and the outer member. A plurality of balls that are interposed between the track groove of the inner member and the track groove of the inner member and transmit a torque, and have a pocket for accommodating the balls, and are interposed between the outer member and the inner member. The cage pocket includes four pairs of a long pocket having a large circumferential interval and a pair of short pockets having a small circumferential interval, and the pair of long pockets extends in the circumferential direction. The pair of short pockets are shifted 180 degrees along the circumferential direction, the long pockets and the short pockets are alternately arranged along the circumferential direction, and two balls are accommodated in the long pockets. And one bow in the short pocket A fixed type constant velocity universal joint housing a, the spherical inlet fitting portions of the outer member corresponding to the long pocket of the cage, provided with a notch to avoid contact with the outer surface of the cage, the notch By providing, the inner diameter of the spherical inlet inlay portion of the outer member corresponding to the long pocket of the cage is made larger than the inner diameter of the other spherical inlet inlay portion.

The second fixed type constant velocity universal joint of the present invention includes an outer member having a plurality of track grooves formed on an inner spherical surface, an inner member having a plurality of track grooves formed on the outer spherical surface, and the outer member. A plurality of balls that are interposed between the track groove of the inner member and the track groove of the inner member and transmit a torque, and have a pocket for accommodating the balls, and are interposed between the outer member and the inner member. The cage pocket includes four pairs of a long pocket having a large circumferential interval and a pair of short pockets having a small circumferential interval, and the pair of long pockets extends in the circumferential direction. The pair of short pockets are shifted 180 degrees along the circumferential direction, the long pockets and the short pockets are alternately arranged along the circumferential direction, and two balls are accommodated in the long pockets. And one bow in the short pocket A fixed type constant velocity universal joint housing a, the spherical inlet fitting portions of the outer member corresponding to the long pocket of the cage, provided with a rounded portion to avoid contact with the outer surface of the cage, the rounded portion By providing, the curvature radius of the round part of the spherical inlet inlay part of the outer member corresponding to the long pocket of the cage is made larger than the curvature radius of the round part of the other spherical inlet inlay part.

  In the first and second fixed type constant velocity universal joints of the present invention, having the long pocket facilitates the incorporation of the inner ring into the cage.

  Even if the phenomenon that the long side opening side edge part of the long pocket facing the long pocket gets over the spherical inner diameter inlet edge part of the outer ring (outer member) is repeated (in the first fixed type constant velocity universal joint, The inner diameter of the spherical inlet spigot portion of the outer member corresponding to the long pocket of the cage is made larger than the inner diameter of the other spherical inlet spigot portion. In the second fixed type constant velocity universal joint, Since the radius of curvature of the rounded portion of the corresponding spherical member inlet spigot of the outer member is larger than the radius of curvature of the rounded portion of the other spherical inlet spigot portion) Sliding contact can be avoided. For this reason, it is possible to prevent surface peeling or the like at the spherical inner diameter inlet edge portion of the outer ring.

It is preferable that the pitch circle diameter of the ball is PCD _BALL , the ball diameter is D _BALL , and the ratio PCD _BALL / D _BALL is 3.0 or more and 3.3 or less. The strength and durability as a constant velocity universal joint can be secured.

  If the ratio of the pitch circle diameter to the ball diameter is less than 3.0, if the ball diameter is large, the thickness of the inner member becomes too thin, which raises concerns about strength. When the diameter is small, the surface pressure between the inner member (inner ring) / outer member (outer ring) and the ball increases, which raises concerns about durability. On the contrary, when the ball diameter exceeds 3.3, when the ball diameter is small, the load capacity of the ball is small, and there is a concern in terms of durability. When the pitch circle diameter of the ball is large, the outer diameter of the outer member is It becomes large and cannot be made compact.

It is preferable that the outer diameter of the outer member is D _OUTER , the ball diameter is D _BALL , and the ratio D _OUTER / D _BALL is 4.6 or more and 4.8 or less. If the ratio between the outer diameter of the outer member and the diameter of the ball is less than 4.6, the outer member becomes too thin when the ball diameter is large. When the outer diameter of the one-way member is small, the surface pressure between the inner member / outer member and the ball increases, and there is a concern in terms of durability. On the other hand, if the diameter exceeds 4.8, the load capacity of the ball becomes small when the ball diameter is small, and there is concern about durability, and compactness cannot be achieved when the outer member has a large outer diameter.

  It is preferable to increase the offset amount of the cage substantially the same as the offset amount of the track groove. As a result, it is possible to prevent the depth of the track groove on the deeper side of the joint from becoming shallow, and to increase the thickness (diameter thickness) of the cage on the opening side.

  The center of curvature of the track groove of the outer member and the center of curvature of the track groove of the inner member are offset in the axial direction by an equal distance from the joint center, and the center of curvature of the outer spherical surface of the cage and the cage A straight line connecting the center of curvature of the outer spherical surface of the cage and the center of the ball when the working angle is 0 °, offset from the center of curvature of the inner spherical surface by an equal distance from the joint center in the axial direction. The angle formed by the straight line connecting the joint center and the ball center, and the angle formed by the straight line connecting the center of curvature of the inner spherical surface of the cage and the ball center, and the straight line connecting the joint center and the ball center, respectively. It is preferable to set the angle between 2.7 ° and 5.7 °.

  By setting the offset angle of the cage to 2.7 ° or more and 5.7 ° or less, the thickness of the end portion on the joint opening side of the cage is formed thicker than other portions. When the offset angle of the cage is less than 2.7 °, the end portion on the joint opening side of the cage becomes thin, and sufficient strength cannot be secured. If the angle exceeds 5.7 °, the thickness of the end of the cage on the back side becomes extremely thin. Heat treatment is generally performed in the cage manufacturing process. However, if the cage thickness becomes extremely thin, the uncured layer due to the heat treatment decreases in the thin portion, and the toughness decreases and sufficient strength cannot be secured. . Moreover, if the thickness difference between the end portion on the joint opening side of the cage and the end portion on the back side of the joint is large, the workability may be deteriorated.

Also, the cage wall thickness at the cage pocket center position is t _CAGE, and the pitch circle radius of the ball when the operating angle is 0 ° is PCR _BALL, and this ratio t _CAGE / PCR _BALL is 0.20 or more It is preferable to set it to 0.23 or less.

In the fixed type constant velocity universal joint of the present invention, since the number of balls is six, relatively large balls can be used, and the column width between the pockets of the cage can be increased. By the way, when t _CAGE / PCR _BALL is less than 0.20, the outer diameter becomes large, making it difficult to make compact, reducing the thickness of the cage, and ensuring the required joint strength at a large angle. It becomes difficult. On the other hand, if t _CAGE / PCR _BALL exceeds 0.23, the inner ring (inner member) of the inner diameter serration part (shaft fitting part) becomes thinner, and the required joint at a large angle (high operating angle) As a result, it becomes difficult to ensure the strength, or the track groove depth of the inner member and the outer member becomes smaller, so that the allowable torque level is lowered. As a result, the ball can easily ride on the edge portions of the track grooves of the inner member and the outer member, and the durability may be significantly reduced. For this reason, by satisfying 0.20 ≦ t _CAGE / PCR _BALL ≦ 0.23, it is possible to reduce the size and improve the cage strength, and to prevent the ball from running onto the edge of the track groove.

  It is also possible to dispose the track grooves of the outer member and the track grooves of the inner member at unequal pitches in the circumferential direction. 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.

  The pitch angle on the PCD of the two balls accommodated in the long pockets was made smaller than 60 degrees, and the pitch angles of the other balls were made larger than 60 degrees. As a result, the distance between the pitches of the two balls stored in the long pocket is reduced, and the distance between the pitches of the outer member and the track groove of the inner member corresponding thereto is reduced. By reducing the distance between the pitches of the two balls contained in the long pocket, the circumferential length of each of the four window pillars between the cage pockets can be increased. The rigidity of the column can be increased.

  At least one of the long sides facing the long pocket may be provided with a pocket inward bulging portion that becomes a non-interfering portion in the inner member when the inner member is assembled. By providing such a pocket inward bulging portion, the rigidity and strength of the cage can be improved. In addition, since the pocket inward bulging portion becomes a non-interfering portion when the inner member is assembled, the assembling property does not deteriorate.

  In the present invention, since the rigidity of each cage window column can be increased, a large ball can be disposed on a small PCD, and the size can be reduced without reducing the load capacity. Moreover, the cage can be prevented from being damaged by a torsional torque load at a high angle. Further, by having the long pocket, it becomes easy to incorporate the inner member into the cage. In particular, by making the axial length of the inner member shorter than the minimum length of the long pockets in the circumferential direction, the inner ring can be more easily assembled into the cage and the assembly workability can be improved. .

  The sliding contact of the outer diameter surface of the cage with the inner diameter inlet edge portion of the outer member can be avoided, and surface peeling or the like at the spherical inner diameter inlet edge portion of the outer member can be prevented. Thereby, the durability as a constant velocity universal joint can be improved, and a stable function can be exhibited over a long period of time.

  By setting the ratio between the pitch circle diameter of the ball and the ball diameter to 3.0 or more and 3.3 or less, the strength and durability of the constant velocity universal joint can be ensured, and high precision constant velocity is possible. A joint can be provided. Further, when the ratio between the outer diameter of the outer member and the diameter of the ball is set to 4.6 or more and 4.8 or less, further strength and durability can be secured. By setting the cage offset angle to 2.7 ° or more and 5.7 ° or less, the thickness of the end of the cage on the joint opening side can be made thicker than other parts. Even if the cage is thinly formed in order to reduce the size and weight, the end portion on the joint opening side of the cage can ensure the strength to withstand the load applied when the joint is rotated at a high operating angle.

By satisfying 0.20 ≦ t _CAGE / PCR _BALL ≦ 0.23, it is possible to reduce the size and improve the cage strength, and to prevent the ball from climbing onto the edge of the track groove. In other words, by setting in this way, it is possible to reduce the size (miniaturization), to ensure the strength of the cage even if the size is reduced, and to prevent the cage from being damaged when a high-angle torsion torque is applied. The strength can be improved. For this reason, the joint strength durability can be ensured to be equal to or higher than that of the conventional product with a more compact form.

  In addition, the pitch angle on the PCD of the two balls accommodated in the long pocket is made smaller than 60 degrees, and the pitch angle of the other balls is made larger than 60 degrees, so that the two balls housed in the long pocket The distance between the pitches of the balls can be reduced, and the distance between the pitches of the track grooves of the outer member corresponding thereto can be reduced. This facilitates the incorporation of the cage into the outer member. In particular, this pitch distance (shoulder width between track grooves) can be made smaller than the pocket width in the cage axial direction, which makes it easier to incorporate the cage into the outer member and improves assembly workability. be able to.

  By providing the pocket inward bulging portion in the long pocket, the rigidity and strength of the cage can be improved. In addition, since the pocket inward bulging portion becomes a non-interfering portion when the inner member is assembled, the assembling property does not deteriorate.

  An embodiment of a fixed type constant velocity universal joint according to the present invention will be described with reference to FIGS.

  The fixed type constant velocity universal joint includes an outer ring 23 as an outer member (outer joint member) in which a plurality of track grooves 22 are formed on an inner spherical surface 21 as shown in FIGS. An inner ring 26 as an inner member (inner joint member) in which a plurality of track grooves 25 that are paired with the track grooves 22 of 23 are formed, and interposed between the track grooves 22 of the outer ring 23 and the track grooves 25 of the inner ring 26. Thus, a plurality of balls 27 for transmitting torque, and a cage 28 for holding the balls 27 interposed between the inner spherical surface 21 of the outer ring 23 and the outer spherical surface 24 of the inner ring 26 are provided.

  The track groove 22 of the outer ring 23 has its center of curvature O1 shifted from the joint center O in the axial direction toward the opening side of the outer ring 23. Further, the center of curvature O2 of the track groove 25 of the inner ring 26 is provided away from the joint center O in the axial direction by an equal distance k on the far side opposite to the center of curvature O1 of the outer ring 23.

  In the cage 28, the center of curvature O3 of the outer spherical surface 28a and the center of curvature O4 of the inner spherical surface 28b are offset in the axial direction by an equal distance k1 with respect to the joint center (cage center) O. The amount is made substantially the same as the offset amount of the track groove.

  The cage 28 is provided with a pocket 29 for accommodating the ball 27. In this case, as shown in FIG. 2, the pockets 29 of the cage 28 have a total of four pairs of a pair of long pockets 30 with a large circumferential interval and a pair of short pockets 31 with a small circumferential interval. Yes. Then, the pair of long pockets 30 are shifted 180 degrees along the circumferential direction, and the pair of short pockets 31 are shifted 180 degrees along the circumferential direction so that the long pockets 30 and the short pockets 31 are alternately positioned along the circumferential direction. Is arranged. For this reason, there are four window pillars 34 (cage window pillars) provided between the pockets.

  The long pocket 30 accommodates two balls 27 and the short pocket 31 accommodates one ball 27. In this case, all the six balls 27 are arranged at an equal pitch (60 ° pitch) along the circumferential direction.

  In the first embodiment, as shown in FIGS. 3 and 4, the inner diameter of the spherical inlet inlay portion of the outer ring 23 corresponding to the long pocket 30 of the cage 28 is made larger than the inner diameter of the other spherical inlet inlay portions. ing. That is, a notch 33 whose notch end surface 33a extends along the axis is provided in a part of the spherical inlet inlay portion of the outer ring 23 (a portion corresponding to the long pocket 30 of the cage 28). The inner diameter S1 (see FIG. 3) of the notch 33 is set larger than the inner diameter S2 (see FIG. 4) of the spherical inlet spigot where the notch 33 is not formed.

  By the way, the operation of incorporating the inner ring 26 into the cage 28 is performed as follows. First, in a state where the inner ring 26 is disposed perpendicular to the axis of the cage 28 (in a state where the inner ring 26 is rotated by 90 ° with respect to the cage 28), the outer ring 24 of the inner ring 26 is The part is dropped into the pocket 29 of the cage 28. In this state, the inner ring 26 is inserted into the cage 28, and then the inner ring 26 is rotated by 90 ° with respect to the cage 28, and the axis of the inner ring 26 is aligned with the axis of the cage 28 and placed in a normal posture.

  For this reason, in the cage 28 according to the present invention, when the inner ring 26 is assembled into the cage 28, a part of the outer spherical surface 24 of the inner ring 26 can be dropped into the long pocket 30, and the inner ring 26 can be easily assembled into the cage. Become.

  Further, even if the phenomenon that the opening side edge portions of the long sides 30a and 30b facing the long pocket 30 ride over the spherical inner diameter inlet edge portion of the outer ring 23 is repeated (corresponding) to the long pocket 30 of the cage 28. Since the inner diameter of the spherical inlet spigot portion of the outer ring 23 is made larger than the inner diameter of the other spherical inlet spigot portion, sliding contact of the outer diameter surface of the cage 28 with respect to the inner diameter inlet edge portion can be avoided. For this reason, surface peeling at the spherical inner diameter inlet edge portion of the outer ring 23 can be prevented, durability as a constant velocity universal joint can be improved, and a stable function can be exhibited over a long period of time.

  Next, in the second embodiment shown in FIGS. 5, 6, and 7, the rounded portion 35 is provided in the spherical inlet inlay portion of the outer ring 23, and the rounded portion 35 a of the portion corresponding to the long pocket 30 of the cage 28 is replaced with another portion. It is made larger than the round part 35b of the spherical inlet inlay part. That is, the radius of curvature R1 of the rounded portion 35a is set larger than the radius of curvature R2 of the rounded portion 35b.

  Since the other structure of the constant velocity universal joint shown in FIG. 5 is the same as that of the constant velocity universal joint shown in FIG. 1, the same members as those in FIG.

  Therefore, the constant velocity universal joints shown in FIGS. 5 to 7 also have the same effects as the constant velocity universal joint shown in FIG. In particular, the rounded portion 35a of the spherical inlet inlay portion of the outer ring 23 corresponding to (positioning) the long pocket of the cage 28 is made larger than the rounded portion 35b of the other spherical inlet inlay portion. Slidable contact of the outer diameter surface of the outer ring can be avoided, and surface separation at the spherical inner diameter inlet edge portion of the outer ring can be prevented.

As shown in FIG. 8, the ratio r1 between the pitch circle diameter PCD _BALL of the ball 27 and the diameter D _{BALL of the} ball 27 is preferably 3.0 or more and 3.3 or less. That is, 3.0 ≦ r1 ≦ 3.3. The ratio r2 between the outer diameter D _OUTER of the outer ring 23 and the pitch circle diameter PCD _BALL of the ball 27 is preferably 4.6 or more and 4.8 or less. That is, 4.6 ≦ r2 ≦ 4.8. Here, the pitch circle diameter PCD _BALL is the diameter of the locus of a circle drawn by the ball center.

By setting PCD _BALL / D _BALL to 3.0 or more and 3.3 or less, the strength and durability as a constant velocity universal joint can be ensured, and a highly accurate constant velocity universal joint can be provided. If the ratio of the pitch circle diameter PCD _BALL to the ball diameter D _BALL is less than 3.0, when the ball 27 has a large diameter, the inner ring 26 is too thin, and there is concern in terms of strength. When the pitch circle diameter PCD _BALL of the ball 27 is small, the surface pressure between the inner ring 26 / outer ring 23 and the ball increases, and there is a concern in terms of durability. On the other hand, when the diameter exceeds 3.3, when the diameter of the ball 27 is small, the load capacity of the ball 27 is small, and there is a concern about durability. When the pitch circle diameter PCD _BALL of the ball 27 is large, the outer ring The outer diameter becomes large and compactness cannot be achieved.

It is preferable that the outer diameter of the outer ring 23 is D _OUTER , the ball diameter is D _BALL , and the ratio D _OUTER / D _BALL is 4.6 or more and 4.8 or less. If the ratio of the outer diameter of the outer ring 23 to the diameter of the ball is less than 4.6, when the diameter of the ball 27 is large, the thickness of the outer ring 23 becomes too thin, and there is a concern in terms of strength. When the outer diameter of the member is small, the surface pressure between the inner member / outer member and the ball is increased, which raises concerns about durability. On the other hand, if the diameter exceeds 4.8, the load capacity of the ball becomes small when the diameter of the ball 27 is small, and there is concern about durability, and compactness cannot be achieved when the outer diameter of the outer ring 23 is large.

  By the way, in the said embodiment, although it was a bar field type (BJ type) which does not have a straight part in a track groove, as shown in FIG. 9, it is an undercut free type (UJ type) which has a straight part in a track groove. It may be.

  That is, in this constant velocity universal joint, the track groove 22 of the outer ring 23 includes a back-side track groove 22a in which the track groove bottom is an arc portion and an opening-side track groove 22b in which the track groove bottom is a straight portion parallel to the outer ring axis. It consists of. The back side track groove 22 a has its center of curvature O 1 shifted from the joint center O in the axial direction toward the opening side of the outer ring 23. The track groove 25 of the inner ring 26 includes a back side track groove 25a in which the track groove bottom is a straight portion parallel to the inner ring axis and an opening side track groove 25b in which the track groove bottom is an arc portion. The center of curvature O2 of the opening side track groove 25b is provided at an equal distance k away from the joint center O in the axial direction on the far side opposite to the center of curvature O1 of the back side track groove 22a of the outer ring 23.

In this case, when the operating angle is 0 °, a straight line L3 connecting the curvature center O3 of the outer spherical surface 28a of the cage 28 and the ball center O5 and a straight line L connecting the joint center O and the ball center O5 are formed. The angle θ3 and the angle θ4 formed by the straight line L4 connecting the center of curvature O4 of the inner spherical surface 28b of the cage 28 and the ball center O5 and the straight line L connecting the joint center O and the ball center O5 are each 2.7 °. The angle is set to 5.7 ° or less. The angles θ3 and θ4 are called cage offset angles (θ _CAGE ). The operating angle of 0 ° is a state where the axis of the outer ring 23 and the axis of the inner ring 26 coincide.

Further, when the operating angle is 0 °, an angle formed by a straight line L1 connecting the curvature center O1 of the track groove 22 of the outer ring 23 and the ball center O5 and a straight line L connecting the joint center O and the ball center O5. θ1 and an angle θ2 formed by a straight line L2 connecting the center of curvature O2 of the track groove 25 of the inner ring 26 and the ball center O5 and a straight line L connecting the joint center O and the ball center O5 are respectively the offset angles (θ _CAGE ). Note that the angles θ1 and θ2 are referred to as track offset angles (θ _TRACK ). In this embodiment, the center of curvature O1 of the track groove 22 of the outer ring 23 is disposed closer to the anti-joint center side than the center of curvature O3 of the outer spherical surface 28a of the cage 28, and the center of curvature O2 of the track groove 25 of the inner ring 26 is It arrange | positions rather than the curvature center O4 of 28 inner spherical surfaces 28b in the anti-joint center side. For this reason, in this embodiment, the track offset angle (θ _TRACK ) is set slightly larger than the cage offset angle (θ _CAGE ).

  By setting the offset angles θ3 and θ4 of the cage 28 to be not less than 2.7 ° and not more than 5.7 °, the thickness of the end portion on the joint opening side of the cage 28 is made thicker than other portions. Even if the cage 28 is thinly formed in order to reduce the size and weight of the joint, the joint opening side end of the cage 28 has sufficient strength to withstand the load applied when the joint is rotated at a high operating angle. be able to. If the offset angles θ3 and θ4 of the cage 28 are less than 2.7 °, the end portion on the joint opening side of the cage 28 becomes thin, and sufficient strength cannot be ensured. If the angle exceeds 5.7 °, the thickness of the end of the cage 28 on the back side of the joint becomes extremely thin. In the manufacturing process of the cage 28, heat treatment is generally performed. However, when the thickness of the cage 28 becomes extremely thin, an uncured layer due to heat treatment is reduced in the thin portion, and the toughness is lowered and sufficient strength is secured. become unable. Further, if the thickness difference between the end portion on the joint opening side of the cage 28 and the end portion on the back side of the joint is large, the workability may be deteriorated.

Further, as shown in FIG. 10, the cage wall thickness at the pocket center position of the cage 28 is t _CAGE, and the pitch circle radius of the ball 27 when the operating angle is 0 ° is PCR _{BALL. CAGE} / PCR _BALL can be set to 0.20 or more and 0.23 or less. Here, the pitch circle radius PCR _BALL is the radius of the locus of a circle drawn by the ball center.

By the way, when t _CAGE / PCR _BALL is less than 0.20, the outer diameter becomes large, it becomes difficult to make compact, the thickness of the cage 28 becomes thin, and the necessary joint strength at a large angle is ensured. It becomes difficult. On the other hand, if t _CAGE / PCR _BALL exceeds 0.23, the inner ring 26 becomes thinner at the inner diameter serration portion (shaft fitting portion), and the required joint strength at a large angle (high operating angle) can be ensured. When the track groove depths of the inner ring 26 and the outer ring 23 become smaller, the allowable torque level decreases. As a result, the ball 27 can easily ride on the edge portions of the track grooves 25 and 22 of the inner ring 26 and the outer ring 23, and the durability may be significantly reduced.

For this reason, by satisfying 0.20 ≦ t _CAGE / PCR _BALL ≦ 0.23, it is possible to reduce the size and improve the cage strength, and to prevent the ball 27 from climbing onto the edge of the track groove. . That is, according to the present invention, it is possible to reduce the size (miniaturization), to secure the strength of the cage 28 even if the size is reduced, and to prevent the cage from being damaged when a high-angle torsional torque load is applied. Can be improved. For this reason, the joint strength durability can be ensured to be equal to or higher than that of the conventional product with a more compact form.

  In the above embodiment, the balls 27 are arranged at equal pitches along the circumferential direction, but may be arranged at unequal pitches as shown in FIG. In this case, the pitch angle β on the PCD of the two balls 27 accommodated in the long pocket 30 is made smaller than 60 degrees, and the other ball 27 pitch angle α is made larger than 60 degrees.

  Thus, by reducing the distance between the pitches of the two balls 27 stored in the long pocket 30, the distance between the pitches of the track grooves 22 of the corresponding outer ring 23 can be reduced. This facilitates the incorporation of the cage 28 into the outer ring 23. As shown in FIG. 12, if this pitch distance (track shoulder width dimension f) is made smaller than the pocket width g in the cage axial direction, this makes it easier to incorporate the cage 28 into the outer ring 23. Assembly workability can be improved.

  By the way, as shown in FIGS. 13, 14, and 15 (a), a bulging portion 36 that protrudes inward of the long pocket at the center in the longitudinal direction of the long sides 30 a and 30 b facing the long pocket 30, 36 may be provided to form two ball accommodating portions 38, 38 connected to the long pocket 30 through the slit 37. In this case, the bulging portions 36, 36 are continuous spherical surfaces having the same curvature radius as the outer spherical surface 28 a of the cage 28, and the inner surfaces are continuous spherical surfaces having the same curvature radius as the inner spherical surface 28 b of the cage 28. In this embodiment, the shape of the bulging portion 36 is a trapezoidal shape (so-called Mt. Fuji shape) whose side is an arc surface when viewed from the cage outer peripheral side.

  For this reason, the projecting end surface 36a of each bulging portion 36 is a plane extending along the circumferential direction of the cage, and is opposed (facing) with a predetermined interval W. Further, the predetermined interval W is made larger than the width dimension (the shoulder width dimension between track grooves) h of the convex portion 47 of the inner ring 26.

  As shown in FIGS. 13 and 14, the predetermined interval W is set to a size that does not interfere with the shoulder 47 (protrusion between adjacent track grooves) of the inner ring 26 during assembly. Also, the size and shape of the bulging portion 36 must be such that the movement of the ball 27 accommodated in the ball accommodating portion 38 is not hindered when rotating with an operating angle. The bulging portion 36 can be formed by machining or plastic working when the long pocket 30 is formed.

  By providing the bulging portions 36 and 36 in the long pocket 30, the rigidity of the frame (window frame) for constituting the long pocket 30 can be improved. As a result, deformation of the cage 28 due to insufficient rigidity of the window frame can be prevented, and the operability of the joint can be maintained, and stable operability can be exhibited over a long period of time.

  As shown in FIG. 15A, the long pocket 30 of the above embodiment has a so-called Mt. Fuji shape with the bulging portions 36, 36, but has a shape as shown in FIGS. 15B, 15C, and 15D. There may be. That is, the bulging portions 36 and 36 in FIG. 15B are rounded at the corners of the protruding end surface 36a of the bulging portion 36, and the bulging portions 36 and 36 in FIG. The bulging portions 36 and 36 in FIG. 15D have a trapezoidal shape in which the base corner portion is not gentle.

  Even the cage 28 having the long pocket 30 shaped as shown in FIGS. 15B, 15C and 15D has the same effects as the cage 28 shown in FIG.

  Moreover, as shown in FIG. 16, you may abbreviate | omit either one of a pair of bulging parts 36 and 36. As shown in FIG. In FIG. 16A, the bulging portion 36 is provided only on the long side 30a side on the joint opening side, and in FIG. 16B, the bulging portion 36 is provided only on the long side 30b side on the coupling back side.

  In the case shown in FIG. 16A, the interference between the inlay edge portion of the opening (entrance) of the outer ring 23 and the pocket edge portion on the cage outer spherical surface 28a side can be delayed or eliminated. In this case, the interference between the back edge portion of the outer spherical surface 24 of the inner ring 26 and the pocket edge portion on the cage inner spherical surface 28b side can be delayed or eliminated. For this reason, the cage 28 can be easily guided to the inner spherical surface 21 of the outer ring 23 and the outer spherical surface 24 of the inner ring 26, and the deterioration of the operability of the joint can be prevented. Together with this, it is possible to effectively prevent the cage 28 from being chipped or cracked.

  By the way, when the cage 28 having the long pockets 30 is manufactured, the window column between the pockets adjacent to each other in the circumferential direction may be removed in the existing cage in which the pockets are formed at a pitch of 60 ° along the circumferential direction. That is, a pair of window pillars in the opposite directions with respect to the cage center may be removed. As described above, the cage 28 can be easily formed by removing the window column in an existing cage, and the window column can be removed by milling even if it is press working. It may be, and can be stably formed by these various plastic workings. In the case of the cage 28 shown in FIGS. 15 and 16, a part of the window column to be removed remains, but in the cage 28 shown in FIGS. 21 and 22, the whole (all) of the window column to be removed is removed. Yes. That is, the long pocket 30 has an oval shape.

  When the inner ring 26 is assembled in the cage 28, one convex portion 47 of the inner ring 26 is dropped into one long pocket 30 of the cage 28 as shown in FIG. For this reason, the pocket inward bulging portion 36 becomes a non-interfering portion with the inner ring when the inner ring is assembled.

  By providing the pocket inward bulging portions 36, 36 in the long pocket 30, the rigidity and strength of the cage 28 can be improved. Moreover, since the bulging portions 36 and 36 become non-interfering sites when the inner ring is assembled, the assembling property is not deteriorated.

  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, in the embodiment, the curvature center O1 and the curvature center O3 are slightly different. Although the center of curvature O2 and the center of curvature O4 are disposed at positions slightly deviated from each other, the center of curvature O2 is provided even if the center of curvature O1 and the center of curvature O3 are the same position. And the center of curvature O4 may be at the same position.

  Further, the interval between the long pockets 30 in the circumferential direction can be variously set within the range in which the ease of assembling the inner ring 26 into the cage 28 can be improved and the rigidity of the window column 34 is not lowered. Further, the shoulder width dimension h between the track grooves and the pocket width of the cage 28 in the cage axial direction can also be set in consideration of the ease of assembling the cage 28 into the outer ring 23.

It is a longitudinal cross-sectional view of the fixed type constant velocity universal joint which shows 1st Embodiment of this invention. It is a cross-sectional view of the fixed type constant velocity universal joint. It is a principal part expanded sectional view of the said fixed type constant velocity universal joint. It is another principal part expanded sectional view of the said fixed type constant velocity universal joint. It is a longitudinal cross-sectional view of the fixed type constant velocity universal joint which shows 2nd Embodiment of this invention. It is a principal part expanded sectional view of the fixed type constant velocity universal joint shown in the said FIG. FIG. 6 is an enlarged cross-sectional view of another main part of the fixed type constant velocity universal joint shown in FIG. 5. It is a cross-sectional view of the fixed type constant velocity universal joint which shows 3rd Embodiment of this invention. It is a longitudinal cross-sectional view of the fixed type constant velocity universal joint which shows 4th Embodiment of this invention. It is a cross-sectional view of the fixed type constant velocity universal joint which shows 5th Embodiment of this invention. It is a cross-sectional view of the fixed type constant velocity universal joint which shows 6th Embodiment of this invention. It is a figure which shows the relationship between a cage and an outer ring | wheel. It is a figure which shows the relationship between another cage and an inner ring. It is a figure which shows a state in the assembly | attachment of the inner ring | wheel to the cage shown in FIG. It is a simplification figure showing the modification of a cage. It is a simplification figure showing the modification of a cage. It is a longitudinal cross-sectional view of the conventional constant velocity universal joint. It is a cross-sectional view of a conventional constant velocity universal joint. It is a longitudinal cross-sectional view of the other conventional constant velocity universal joint. It is a cross-sectional view of another conventional constant velocity universal joint. It is a front view of a cage. It is a perspective view of a cage. It is sectional drawing of the state in which the other conventional constant velocity universal joint took the operating angle. It is a front view in the state where a cage was damaged.

Explanation of symbols

21 inner spherical surface 22 track groove 24 outer spherical surface 25 track groove 27 ball 28 cage 28a outer spherical surface 28b inner spherical surface 29 pocket 30 long pocket 31 short pocket

Claims (10)

An outer member having a plurality of track grooves formed on the inner spherical surface, an inner member having a plurality of track grooves formed on the outer spherical surface, and between the track grooves of the outer member and the track grooves of the inner member. A plurality of balls interposed to transmit torque; and a cage having a pocket for accommodating the balls and interposed between the outer member and the inner member, the pockets of the cage being spaced apart in the circumferential direction Has four pairs of a large pair of long pockets and a pair of short pockets with a small circumferential interval, and the pair of long pockets is shifted 180 degrees along the circumferential direction, and the pair of short pockets is circumferential The long pockets and the short pockets are alternately arranged along the circumferential direction, and two balls are accommodated in the long pockets, and one ball is accommodated in the short pockets. Fixed type constant velocity universal joint ,
A notch that avoids contact with the outer diameter surface of the cage is provided in the spherical inlet inlay portion of the outer member corresponding to the long pocket of the cage, and the outer side corresponding to the long pocket of the cage is provided by providing this notch. A fixed type constant velocity universal joint characterized in that the inner diameter of the spherical inlet inlay portion of the member is larger than the inner diameter of the other spherical inlet inlay portion. An outer member having a plurality of track grooves formed on the inner spherical surface, an inner member having a plurality of track grooves formed on the outer spherical surface, and between the track grooves of the outer member and the track grooves of the inner member. A plurality of balls interposed to transmit torque; and a cage having a pocket for accommodating the balls and interposed between the outer member and the inner member, the pockets of the cage being spaced apart in the circumferential direction Has four pairs of a large pair of long pockets and a pair of short pockets with a small circumferential interval, and the pair of long pockets is shifted 180 degrees along the circumferential direction, and the pair of short pockets is circumferential The long pockets and the short pockets are alternately arranged along the circumferential direction, and two balls are accommodated in the long pockets, and one ball is accommodated in the short pockets. Fixed type constant velocity universal joint ,
A spherical portion that avoids contact with the outer diameter surface of the cage is provided in the spherical inlet inlay portion of the outer member corresponding to the long pocket of the cage, and the outer portion corresponding to the long pocket of the cage is provided by providing this rounded portion. spherical inlet spigot portion of the radius of curvature of the rounded portion, the other spherical inlet fitting portions of the rounded portion fixed type constant velocity universal joint, characterized in that is larger than the radius of curvature of the member. The pitch circle diameter of the ball is PCD _BALL , the ball diameter is D _BALL , and the ratio PCD _BALL / D _BALL is 3.0 or more and 3.3 or less. Fixed fixed velocity universal joint according to 2. The outer diameter of the outer member is D _OUTER , the ball diameter is D _BALL , and the ratio of D _OUTER / D _BALL is 4.6 to 4.8. Item 4. The fixed type constant velocity universal joint according to any one of items 3 to 4.   The fixed type constant velocity universal joint according to any one of claims 1 to 4, wherein the offset amount of the cage is increased to be substantially the same as the offset amount of the track groove.   The center of curvature of the track groove of the outer member and the center of curvature of the track groove of the inner member are offset in the axial direction by an equal distance from the joint center, and the center of curvature of the outer spherical surface of the cage and the cage A straight line connecting the center of curvature of the outer spherical surface of the cage and the center of the ball when the working angle is 0 °, offset from the center of curvature of the inner spherical surface by an equal distance from the joint center in the axial direction. The angle formed by the straight line connecting the joint center and the ball center, and the angle formed by the straight line connecting the center of curvature of the inner spherical surface of the cage and the ball center, and the straight line connecting the joint center and the ball center, respectively. The fixed type constant velocity universal joint according to any one of claims 1 to 5, wherein the fixed type constant velocity universal joint is set to 2.7 ° or more and 5.7 ° or less. The cage wall thickness at the cage pocket center position is t _CAGE, and the pitch circle radius of the ball when the operating angle is 0 ° is PCR _BALL, and this ratio t _CAGE / PCR _BALL is 0.20 or more and 0.0. The fixed constant velocity universal joint according to any one of claims 1 to 6, wherein the fixed constant velocity universal joint is set to 23 or less.   8. The fixed type constant velocity free according to claim 1, wherein the track grooves of the outer member and the track grooves of the inner member are arranged at unequal pitches in the circumferential direction. 9. Fittings.   The pitch angle on the PCD of the two balls accommodated in the long pocket is made smaller than 60 degrees, and the pitch angle of the other balls is made larger than 60 degrees. 9. The fixed type constant velocity universal joint according to any one of items 8 to 9.   10. The pocket inward bulging portion, which becomes a non-interfering portion in the inner member when the inner member is assembled, is provided on at least one of the long sides facing the long pocket. The fixed type constant velocity universal joint of any one of these.

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