JP2007024106A - Fixed type constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixed type constant velocity universal joint with a cage easily incorporated into an outer ring without causing the degradation of strength and durability and the loss of transmission torque. <P>SOLUTION: The fixed type constant velocity universal joint comprises the outer ring 25 having a plurality of track grooves 22 formed in an inner spherical face 21, an inner ring having a plurality of track grooves in the outer spherical face, a plurality of balls laid between the outer ring 25 and the inner ring for transmitting torque, and the cage 30 laid between the outer ring 25 and the inner ring for holding the balls. The opening side groove bottom of the track groove 22 of the outer ring 25 is tapered, and the corner side groove bottom of the track groove of the inner ring is tapered. The center of each of the outer and inner spherical faces of the cage 30 and the curvature center of the track groove 22 of each of the outer ring 25 and the inner ring are offset an axially equal distance from the center of the joint to the opposite side. An outer spherical face 32 located at the opening end of a pocket 33 of the cage 30 is partially cut, and an outer diameter ϕd<SB>1</SB>of the cage 30 on a flat cut face 40 thereof is set smaller than an in-low diameter ϕD<SB>1</SB>of the outer ring 25. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  In recent years, the wheelbase may be lengthened from the viewpoint of expanding the riding space of an automobile, but in order to prevent the turning radius of the vehicle from increasing accordingly, a fixed type used as a coupling joint for an automobile drive shaft or the like. There is a need to increase the steering angle of the front wheels by increasing the angle of the constant velocity universal joint.

  Generally, as shown in FIG. 18, the 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 toward the opening end 3 along the axial direction. An outer ring 5, an inner ring 8 as an inner joint member in which a plurality of track grooves 7 paired with the track groove 2 of the outer ring 5 are formed on the outer spherical surface 6 along the axial direction at equal intervals in the circumferential direction, and the outer ring 5 Between the track groove 2 of the inner ring 8 and the track groove 7 of the inner ring 8 to transmit torque, and between the inner spherical surface 1 of the outer ring 5 and the outer spherical surface 6 of the inner ring 8, the balls 9 And a cage 10 for holding the

Since the fixed type constant velocity universal joint for the above-mentioned needs for increasing the angle has a structure capable of obtaining a large operating angle, the curvature center O ₃ of the inner spherical surface 11 of the cage 10 and the curvature of the outer spherical surface 12 as shown in FIG. The center O ₄ is offset in the axial direction by an equal distance f with respect to the joint center plane P (cage offset). Further, the center of curvature O ₁ of the track groove ₂ of the outer ring 5 and the center of curvature O ₂ of the track groove 7 of the inner ring 8 are the center of curvature O ₄ of the inner spherical surface 1 of the outer ring 5 and the center of curvature O ₃ of the outer spherical surface 6 of the inner ring 8. Is offset in the axial direction by an equal distance F (track offset). The center of curvature O ₃ of the outer spherical surface 6 of the inner ring 8 and the center of curvature O ₄ of the inner spherical surface 1 of the outer ring 5 coincide with the centers of curvature of the inner and outer spherical surfaces 11 and 12 of the cage 10, respectively. (For example, see Patent Documents 1 to 3).

By providing the above-described track offset, a pair of track grooves 2 and 7 form a wedge-shaped ball track in which the radial interval gradually increases from the back side of the outer ring 5 toward the opening end side. Further, by providing a cage offset, the cage 10 has a cross-sectional shape that is thin on the back side of the outer ring 5 and thick on the opening end side. In this fixed type constant velocity universal joint, in order to realize use in a high angle region, the above-described cage offset is set large, and the thick portion of the cage 10 is arranged on the opening end side of the outer ring 5.
JP 2001-153149 A JP 2001-304282 A JP 2001-349332 A

  By the way, in the fixed type constant velocity universal joint disclosed in each of Patent Documents 1 to 3, the cage offset is set large in order to realize the operation in the high angle region, while the track offset is made small.

  FIG. 19 shows a state in which the joint has a maximum operating angle θ, that is, a state in which the rotation axis X of the outer ring 5 and the rotation axis Y of the inner ring 8 have the maximum operating angle θ. When the track offset is provided, the portion of the outer ring 5 located on the back side of the track groove 2 becomes shallow. Therefore, for example, when the joint takes the maximum operating angle, the phase where the ball 9 is located on the farthest side (phase angle φ = 180 °), the ball 9 may run from the track groove 2 of the outer ring 5.

  Therefore, by setting this track offset small, the portion of the outer ring 5 located on the back side of the track groove 2 is prevented from becoming shallow, and the riding of the ball 9 located at the innermost part of the track groove 2 is suppressed. ing.

However, when the track offset is set to be small as described above, the holding angle (spherical angle) γ with which the outer ring 5 holds the cage 10 becomes small as shown in FIG. Here, the holding angle (spherical angle) γ means an angle formed by the opening side end portion of the inner spherical surface 1 of the outer ring 5 with respect to the joint center plane P. In such a constant velocity universal joint, in order to easily incorporate the cage 10 into the outer ring 5, the inner ring diameter φD ₀ of the outer ring 5 is changed to the outermost diameter φd ₀ of the cage 10 as shown in FIGS. In this case, the holding angle (spherical angle) γ in the outer ring 5 is further reduced. As a result, the strength and durability of the constant velocity universal joint are reduced and the transmission torque is lost.

  Therefore, the present invention has been proposed in view of the above-described problems, and the object of the present invention is to easily incorporate the cage into the outer ring without causing a decrease in strength and durability and loss of transmission torque. An object of the present invention is to provide a fixed type constant velocity universal joint that can be used.

  As technical means for achieving the above object, the present invention provides an outer joint member in which a plurality of track grooves are formed on the inner spherical surface at equal intervals in the circumferential direction toward the opening end along the axial direction. Torque by interposing between the track grooves of the outer joint member and the inner joint member, the inner joint member having a plurality of track grooves paired with the track grooves of the outer joint member formed along the axial direction at equal intervals in the circumferential direction And a cage for holding the ball interposed between the inner spherical surface of the outer joint member and the outer spherical surface of the inner joint member, and the opening-side groove bottom of the track groove of the outer joint member The taper has a diameter that is linearly expanded toward the inner surface, and the inner groove of the track groove of the inner joint member has a diameter that is linearly expanded toward the inner end. Center is equidistant in the axial direction with respect to the joint center In the fixed type constant velocity universal joint, 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 from the joint center by a cage offset amount. The outer spherical surface located on the opening end side of at least two opposing pockets of the outer surface is partially cut, and the outer diameter of the cage at the cut portion is set smaller than the inner diameter of the outer joint member. To do.

  In the present invention, the outer spherical surface located on the open end side of at least two opposing pockets of the cage is partially cut. In this case, the contact point with the ball can be secured in a state where the constant velocity universal joint has a maximum operating angle, that is, in a state where the rotation shaft of the outer joint member and the rotation shaft of the inner joint member take the maximum angle. The outer spherical surface located on the opening end side of the pocket is partially cut up to.

  Here, the degree to which the contact point with the ball can be secured means that the constant velocity universal joint has the maximum operating angle, and the phase where the ball is most likely to jump out (phase angle φ = 0 °) This means that the ball can be prevented from jumping out of the pocket. Moreover, partial cutting may be performed for at least two opposing pockets of the cage, but partial cutting may be performed for all opposing pockets. At least two opposing pockets are used when inserting the cage into the outer joint member, inserting the cage into the outer joint member with the cage axis perpendicular to the axis of the outer joint member, and In order to rotate the cage by 90 ° so that its axis coincides with the axis of the outer joint member, when inserting the cage, partial cuts are made for two opposing pockets, and the outer diameter of the cage at the cut portion is set to the outer joint. This is because the cage can be inserted into the outer joint member if it is set smaller than the inlay diameter of the member.

  In the present invention, the outer spherical surface located on the opening end side of at least two opposing pockets of the cage is partially cut, and the outer diameter of the cage at the cut portion is set smaller than the inner diameter of the outer joint member. As a result, the outermost diameter of the cage can be made smaller than in the prior art while securing the strength of the cage, and consequently the inner diameter of the outer joint member can be made smaller. ) Does not become small, it is easy to incorporate the cage into the outer joint member without degrading the strength and durability of the constant velocity universal joint and loss of transmission torque.

  The cage having the above-described configuration has a tapered shape in which the opening end of the outer spherical surface extends in the axial direction and the opening end of the inner spherical surface of the cage expands toward the opening end of the outer spherical surface. Such a structure is desirable. Here, when the opening side end of the outer spherical surface of the cage is extended in the axial direction, the shaft attached to the inner joint member is the opening side of the cage with the constant velocity universal joint having the maximum operating angle. The opening side end of the outer spherical surface is extended to the extent that it does not interfere with the end.

  When the open end of the outer spherical surface of the cage is extended to the extent that the shaft does not interfere with the open end of the cage, the taper angle of the open end of the inner spherical surface of the cage is determined by the outer joint member and the inner joint member. It is desirable to make it more than half of the maximum operating angle. Thus, if the taper angle is set to more than half of the maximum operating angle, it is preferable in that the contact area between the outer spherical surface of the cage and the inner spherical surface of the outer joint member can be secured even in a high angle region. If this taper angle is smaller than half of the maximum operating angle, the shaft will interfere with the tapered opening side end of the cage.

  In this way, the contact area between the outer spherical surface of the cage and the inner spherical surface of the outer joint member can be ensured even in a high angle region, so that when the maximum operating angle is taken, the ball pushes the cage toward the opening side, Even if the opening-side end portion of the outer spherical surface and the inner spherical surface of the outer joint member rub against each other strongly, it is possible to minimize a decrease in durability and loss of transmission torque due to heat generation. Moreover, since the rigidity of the cage can be ensured to the maximum, the strength of the cage itself is also improved.

  On the other hand, when a torque exceeding an allowable level is applied to the constant velocity universal joint in the dynamic torsion mode, the track grooves of the outer joint member and the inner joint member are deformed, and the track groove edge is raised. This swell interferes with the cage spherical surface and restrains the cage movement. At this time, there is a possibility that cracks, chips or the like may occur in the edge portion of the pocket that is formed along the circumferential direction of the cage and accommodates the ball.

  Therefore, in the present invention, it is desirable that at least one of the edge portions of the pocket in the above-described configuration on the inner spherical surface side or the outer cage spherical surface side has a spherical R shape. Since the bulge at the track groove edge of the inner joint member easily interferes with the inner spherical surface of the cage, it is preferable that the edge portion on the inner spherical surface side of the pocket has a spherical R shape. The edge portions of the pockets may also have a spherical R shape, and it is optimal if the edge portions on both the inner spherical surface side and the outer spherical surface side of the pocket have a spherical R shape. The “spherical R shape” means a spherical continuous curved surface that smoothly connects the inner spherical surface or outer spherical surface of the cage and the end surface of the pocket.

  If the pocket inner spherical surface or cage outer spherical surface edge of the pocket has a spherical R shape as described above, even if the rise of the track groove edge interferes with the cage spherical surface, cracking or chipping occurs at the pocket edge. The strength of the cage can be ensured.

  Further, when the rise of the track groove edge interferes with the cage spherical surface and the movement of the cage is restrained, stress concentrates on the thin side corner of the pocket.

  Therefore, in the present invention, it is desirable to set the radius of curvature of the thin side corner of the pocket in the above-described configuration to be larger than the radius of curvature of the thick side corner and smaller than the radius of the ball.

  Thus, if the radius of curvature of the thin-walled corner of the pocket is larger than the radius of curvature of the thick-walled corner and smaller than the radius of the ball, as described above, the rise of the track groove edge interferes with the cage spherical surface. However, the stress concentration at the thin wall corner can be relaxed, and the stress balance at the thin wall corner and the thick wall corner can be optimized. Can be secured.

  If the radius of curvature of the thin-walled corner of the pocket is equal to or less than the radius of curvature of the thick-walled corner, it will be difficult to alleviate the stress concentration on the thin-walled corner of the pocket, and the pocket If the radius of curvature of the side corner is equal to or greater than the ball radius, the thin side corner will interfere with the ball when the ball contacts the pillar between the pockets.

  In the present invention, by forming both track grooves of the outer joint member and the inner joint member into a tapered shape, it is possible to easily increase the operating angle without increasing the outer diameter of the outer joint member. In order to prevent the strength and workability of the outer joint member from being reduced even if the thickness of the member is reduced, the effects of tapering the track groove in the internal specifications of this fixed type constant velocity universal joint and The tendency was verified, and the upper limit value was defined as 12 ° as the optimum value of the taper angle of the track groove.

  The present applicant will proceed with the study using static internal force analysis and finite element method (FEM) analysis while securing strength and durability, which are the basic performance required in the past, and narrow the range of the taper angle of the track groove. Was set optimally. And the consistency with the evaluation result and analysis result of the sample which changed the taper angle was confirmed.

  In the above-described configuration, the cage offset amount f between the outer spherical center and the inner spherical center of the cage, the center of curvature of the track groove of the outer joint member or the center of curvature of the track groove of the inner joint member at the operating angle of 0 °, and the ball It is desirable that the value f / PCR of the ratio of the length of the line segment connecting the centers to the PCR is 0.12 or less. Since the cage offset amount f is related to the thickness difference in the longitudinal section of the cage, it is desirable to set the cage offset amount f in consideration of this point.

  For example, if the cage offset amount f is set large so that the thick side of the cage is positioned on the open end side of the outer joint member, the thickness of the cage on the open end side of the outer joint member is increased. There is an advantage that the strength can be improved. Further, by increasing the thickness of the cage on the opening end side of the outer joint member, the ball that is about to jump out from the opening end of the outer joint member can be restrained by the cage when the operating angle is taken.

  However, if the cage offset amount f is too large, the amount of movement of the ball in the cage pocket in the circumferential direction increases, and it is necessary to increase the circumferential dimension of the cage pocket in order to ensure proper movement of the ball. The pillar portion of the cage becomes thin, and the strength becomes a problem. Moreover, the thickness of the back side located on the opposite side to the entrance side of the cage is reduced, and the strength is a problem.

  From the above, it is not preferable that the cage offset amount f is excessive, and there exists an optimum range in which the significance of providing the cage offset amount f can be balanced with the above-described strength problem. However, since the optimum range of the cage offset amount f varies depending on the size of the joint, it needs to be determined in relation to the basic dimension representing the size of the joint. Therefore, the ratio f / PCR of the cage offset amount f and the length PCR of the line segment connecting the center of curvature of the track groove of the outer joint member or the center of curvature of the track groove of the inner joint member and the center of the ball is used.

  Therefore, the cage offset amount f in the above-described configuration connects the cage offset amount f and the center of curvature of the track groove of the outer joint member or the center of curvature of the track groove of the inner joint member and the center of the ball when the operating angle is 0 °. It is desirable that the ratio f / PCR with the line segment length PCR is larger than 0 and not more than 0.12.

  If this ratio f / PCR is larger than 0.12, there is a problem in the aforementioned strength. Conversely, if it is 0 or less, the significance of providing the cage offset amount f is lost. That is, a large purpose of the cage offset is to stabilize the position of the ball and hold the ball on the bisected surface by offsetting the track groove centers of the outer joint member and the inner joint member in the axial direction. Without this offset, the position of the ball cannot be determined, so the objective cannot be achieved within a range of 0 or less. Therefore, from the viewpoint of ensuring cage strength and durability, the optimum range of the cage offset amount f is that the ratio f / PCR is greater than 0 and 0.12 or less.

  According to the present invention, the outer spherical surface located on the opening end side of at least two opposing pockets of the cage is partially cut, and the outer diameter of the cage at the cut portion is smaller than the inner diameter of the outer joint member. By setting, the outermost diameter of the cage and the spigot diameter of the outer joint member can be made smaller than before while securing the strength of the cage, so that the holding angle (spherical angle) in the outer joint member does not become smaller. Therefore, the cage can be easily assembled into the outer joint member without degrading the strength and durability of the constant velocity universal joint and loss of transmission torque, improving the quality and assembly of the constant velocity universal joint. At the same time.

  An embodiment of a fixed type constant velocity universal joint according to the present invention will be described in detail below.

  The constant velocity universal joint of the embodiment shown in FIG. 1 has an outer joint member having a mouth portion 24 in which a plurality of track grooves 22 are formed on an inner spherical surface 21 at equal intervals in the circumferential direction toward the opening end 23 along the axial direction. An outer ring 25, an inner ring 28 that is an inner joint member in which a plurality of track grooves 27 that are paired with the track grooves 22 of the outer ring 25 are formed along the axial direction at equal intervals in the circumferential direction, and the outer ring 25. Between the track groove 22 of the inner ring 28 and the track groove 27 of the inner ring 28 to transmit torque, and between the inner spherical surface 21 of the outer ring 25 and the outer spherical surface 26 of the inner ring 28, each ball 29 is interposed. The cage 30 to hold | maintain is provided. The plurality of balls 29 are accommodated in pockets 33 formed in the cage 30 and arranged at equal intervals in the circumferential direction.

  For example, a driven shaft (not shown) is connected to a stem portion (not shown) integrally extending from the mouse portion 24 of the outer ring 25 described above, and a drive shaft (not shown) is coupled to the inner ring 28 by serration or the like. Thus, the torque can be transmitted while allowing the operating angle displacement between the driven shaft and the drive shaft.

  Each track groove 22 of the outer ring 25 has a tapered shape in which the opening side groove bottom is linearly expanded toward the opening end 23 of the outer ring 25. That is, the track groove 22 has an arc bottom 22 a on the back side of the mouse part 24 and a tapered bottom 22 b on the opening side of the mouse part 24. On the other hand, each track groove 27 of the inner ring 28 has a tapered shape in which the inner side groove bottom is linearly expanded toward the inner end of the inner ring 28. That is, the track groove 27 has an arc bottom 27 a on the opening side of the mouse part 24 and a tapered bottom 27 b on the back side of the mouse part 24.

  Here, FIG. 1 shows a state where the operating angle is 0 °, and FIG. 2 shows a state where the operating angle is the maximum operating angle θ. The operating angle means an angle formed by the rotation axis X of the outer ring 25 and the rotation axis Y of the inner ring 28. Further, when the rotation axis X of the outer ring 25 and the rotation axis Y of the inner ring 28 take an operating angle other than 0 °, a plane perpendicular to the bisector of the angle θ formed by both the rotation axes X and Y is the joint center. This is referred to as plane P. If all the balls 29 are on the joint center plane P when the operating angle θ is taken, the distances from the ball center to the two rotation axes X and Y are equal to each other. Rotational motion is transmitted at. The intersection of the joint center plane P and the rotation axes X and Y is referred to as a joint center O. In the fixed type constant velocity universal joint, the joint center O is fixed regardless of the operating angle θ.

  FIG. 3A shows the cage 30 of the embodiment in FIG. 3A, and a conventional cage 10 (see FIG. 18) is shown in FIG. 4 is a left side view of the cage 30 of the embodiment shown in FIG. 3A, and FIG. 5 is a cross-sectional view of FIG.

The cage 30 of this embodiment partially cuts the outer spherical surface 32 located on the opening end side of the pocket 33, and the outer diameter φd ₁ of the cage 30 on the flat cut surface 40 is set to the inlay diameter of the outer ring 25. It is set smaller than φD ₁ (see FIG. 2). As shown in FIG. 2, in a state where the rotation axis X of the outer ring 25 and the rotation axis Y of the inner ring 28 take the maximum operating angle θ, it is positioned on the opening end side of the pocket 33 to the extent that a contact point with the ball 29 can be secured. What is necessary is just to cut partially the outer spherical surface 32 to perform. Here, the degree to which the contact point with the ball 33 can be secured means that the constant velocity universal joint has the maximum operating angle θ and the phase at which the ball 29 is most likely to jump out (phase angle φ = 0 °). This means that the ball 29 can be prevented from jumping out of the pocket 33 of the cage 30.

  In this embodiment, as shown in FIGS. 4 and 5, the cut surfaces 40 are formed for all the pockets 33 arranged at equal intervals in the circumferential direction. However, it is not always necessary to form all the pockets 33. The cut surface 40 may only be formed for at least two opposing pockets 33.

The at least two pockets 33 opposed to each other are formed when the cage 30 is incorporated in the outer ring 25 as shown in FIG. 6, and the cage 30 is placed in the outer ring 25 with the axis of the cage 30 orthogonal to the axis of the outer ring 25. After the insertion, the cage 30 is rotated by 90 ° so that its axis coincides with the axis of the outer ring 25. Therefore, when the cage 30 is inserted, the two pockets 33 facing each other are partially cut and flattened. This is because the cage 30 can be inserted into the outer ring 25 if the outer diameter φd ₁ of the cage 30 on the cut surface 40 is set smaller than the inner diameter φD ₁ of the outer ring 25.

As in this embodiment, the outer spherical surface 32 located on the opening end side of the pocket 33 of the cage 30 is partially cut, and the outer diameter φd ₁ of the cage 30 on the flat cut surface 40 is set to the inlay of the outer ring 25. By setting the diameter smaller than the diameter φD _1, the outer diameter φd _{1 of the} cage 30 (<the outermost diameter φd ₀ of the conventional cage 10) can be made smaller than the conventional one while securing the strength of the cage 30. Since the inner ring diameter φD ₁ of the outer ring 25 (<the conventional inner ring diameter φD ₀ of the outer ring 5) can be reduced, the holding angle (spherical angle) γ (see FIG. 2) of the outer ring 25 does not become smaller, so constant velocity. The cage 30 can be easily assembled into the outer ring 25 without causing a decrease in the strength and durability of the universal joint and loss of transmission torque.

  In addition, as shown in FIGS. 3A and 3B, the cage 30 has an end on the opening side of the outer spherical surface 32 extending in the axial direction as compared with the conventional product, and an opening side end of the inner spherical surface 31. A tapered surface 34 whose diameter is enlarged toward the opening side end of the outer spherical surface 32 is formed. At the opening side end of the cage 30, the shaft 50 attached to the inner ring 28 by serration fitting with the outer ring 25 and the inner ring 28 having the maximum operating angle θ as shown in FIG. The opening side end of the outer spherical surface 32 is extended to the extent that it does not interfere with the end.

  When the opening side end portion of the outer spherical surface 32 of the cage 30 is extended to the extent that the shaft 50 does not interfere with the opening side end portion of the cage 30, the tapered surface 34 positioned at the opening side end portion of the inner spherical surface 31 of the cage 30. It is desirable that the taper angle θ / 2 be at least half of the maximum operating angle θ formed by the outer ring 25 and the inner ring 28. Thus, if the taper angle θ / 2 of the taper surface 34 is set to be not less than half of the maximum operating angle θ, a contact area between the outer spherical surface 32 of the cage 30 and the inner spherical surface 21 of the outer ring 25 can be secured even in a high angle region. it can. If the taper angle θ / 2 is smaller than half of the maximum operating angle θ, the shaft 50 interferes with the opening side end portion of the cage 30.

  Thus, even in a high angle region, the contact area between the outer spherical surface 32 of the cage 30 and the inner spherical surface 21 of the outer ring 25 can be secured, so that the ball 29 moves the cage 30 toward the opening side when the maximum operating angle θ is taken. Even if the opening side end of the outer spherical surface 32 of the cage 30 and the inner spherical surface 21 of the outer ring 25 rub against each other strongly, it is possible to minimize a decrease in durability and loss of transmission torque due to heat generation. Moreover, since the rigidity of the cage 30 can be ensured to the maximum, the strength of the cage 30 itself is also improved.

  FIG. 7 shows an embodiment in which the edge portion 35 connecting the cage inner spherical surface 31 and the pocket end surface 39 of the pocket 33 has a spherical R shape in the cage 30 described above. The spherical R shape is a spherical continuous curved surface that smoothly connects the inner spherical surface 31 of the cage 30 and the end surface 39 of the pocket 33. The edge portion 35 on the inner spherical surface side of the cage is formed over the entire periphery of the opening edge of the pocket 33. FIG. 8 shows an embodiment in which the edge portion 35 on the spherical surface inside the cage of the pocket 33 has a spherical R shape, and the edge portion 36 on the spherical surface side of the cage also has a spherical R shape. The edge portion 36 on the cage outer spherical surface side also has a spherical R shape that is a spherical continuous curved surface that smoothly connects the outer spherical surface 32 of the cage 30 and the end surface 39 of the pocket 33. It is formed over.

  Thus, if the edge portions 35 and 36 on the inner spherical surface side or the outer spherical surface side of the pocket 33 have a spherical R shape, when a torque exceeding an allowable level is applied to the constant velocity universal joint in the dynamic torsion mode, Even if the rise of the track groove edges of the outer ring 25 and the inner ring 28 interferes with the inner spherical surface 31 and the outer spherical surface 32 of the cage 30, the edge portions 35 and 36 of the pocket 33 are less likely to be cracked or chipped. Strength can be secured.

  The cage 30 has a shape that is thick toward the opening end side of the outer ring 25 and thin toward the back side by providing a cage offset as described later. In this cage 30, as shown in FIG. 9, the radius of curvature of the thin side corner 37 of the pocket 33 is set larger than the radius of curvature of the thick side corner 38 and smaller than the radius of the ball 29. In addition, in order to make it easy to compare the curvature radius of the thin-side corner portion 37 of the pocket 33 with the curvature radius of the thick-side corner portion 38, FIG. FIG. 11 shows a case where the radius of curvature of the thin side corner 37 of the pocket 33 is set to the minimum value Rmin which is the same as the radius of curvature of the thick side corner 38, and FIG. The case where the radius of curvature of the side corner 37 is set to the maximum value Rmax that is the same as the radius of the ball 29 is shown.

  Thus, by increasing the radius of curvature of the thin side corner 37 of the pocket 33 to be larger than the radius of curvature of the thick side corner 38 and smaller than the radius of the ball 29, the track groove edge rises as described above. Even if the movement of the cage 30 is constrained by interfering with the inner spherical surface 31 and the outer spherical surface 32 of the cage 30, stress concentration on the thin-side corner 37 of the pocket 33 can be alleviated. The stress balance at the thick side corner 38 can be optimized, and as a result, the strength of the cage 30 can be ensured.

  According to the FEM analysis, if the radius of curvature of the thin-walled corner 37 of the pocket 33 is increased, the stress generated at that portion decreases and approaches the stress value of the thick-walled corner 38. Even if the rise of the track groove edge interferes with the inner spherical surface 31 and the outer spherical surface 32 of the cage 30 and restrains the cage 30, the allowance until the cage 30 is damaged increases. Can be secured.

  FIG. 13 shows an enlarged cross section (hatching is omitted) of FIG. 1 in order to explain the shapes of the track grooves 22 and 27 of the outer ring 25 and the inner ring 28, the track offset and the cage offset.

In the constant velocity universal joint according to this embodiment, the center of curvature O ₃ of the inner spherical surface 31 of the cage 30 and the center of curvature O ₄ of the outer spherical surface 32 are located on the joint central plane P in order to obtain a structure that can have a large operating angle. On the other hand, they are offset in the opposite axial direction by an equal distance f (cage offset). Further, the center of curvature O ₁ of the track groove 22 of the outer ring 25 and the center of curvature O ₂ of the track groove 27 of the inner ring 28 are the center of curvature O ₄ of the inner spherical surface 21 of the outer ring 25 and the center of curvature of the outer spherical surface 26 of the inner ring 28. It is offset in the axial direction by an equal distance F from O ₃ (track offset). The center of curvature O ₃ of the outer spherical surface 26 of the inner ring 28 and the center of curvature O ₄ of the inner spherical surface 21 of the outer ring 25 coincide with the centers of curvature of the inner and outer spherical surfaces 31 and 32 of the cage 30, respectively.

  In this way, the pair of track grooves 22 and 27 forms a wedge-shaped ball track in which the radial interval gradually increases from the back side of the outer ring 25 toward the opening end side. Each ball 29 is incorporated between a pair of track grooves 22 and 27 so as to be able to roll. When the torque is transmitted with the outer ring 25 and the inner ring 28 having the operating angle θ, the interval between the wedge-shaped ball tracks is wide. Receives an axial force to move in the direction.

When the outer ring 25 and the inner ring 28 have the maximum operating angle θ, the cage offset amount f is set so that the ball 29 can be restrained by the pocket 33 of the cage 30 in order to prevent the ball 29 from jumping out from the open end 23 of the mouth portion 24 of the outer ring 25. Is set larger than the conventional one. That is, the cage offset amount is f and the radius of the center locus of the ball 29 at the operating angle of 0 °, that is, the center of curvature O ₁ of the track groove 22 of the outer ring 25 or the center of curvature O ₂ of the track groove 27 of the inner ring 28 and the ball 29. when the length of a line connecting the center _{O 5} and PCR, f / PCR is greater than 0, and is set to be 0.12 or less.

  Thus, if both the track grooves 22 and 27 of the outer ring 25 and the inner ring 28 are tapered, the maximum operating angle can be increased and the contact length with the ball 29 in the track groove 22 of the outer ring 25 can be secured. Therefore, stable torque transmission can be ensured between the outer ring 25 and the inner ring 28. Further, since the track load and the pocket load of the phase (phase angle φ = 0 °) (see FIGS. 2 and 14) in which the ball 29 is most likely to jump out when the operating angle is taken can be reduced. This is advantageous in the operation of the inner ring 28 in a high angle region. Here, the track load and the pocket load mean a load received by the track grooves 22 and 27 or the pocket 33 from the ball 29 in contact therewith.

  Further, the outer spherical surface 32 of the cage 30 is contact-guided to the inner spherical surface 21 of the outer ring 25, and the inner spherical surface 31 of the cage 30 is contact-guided to the outer spherical surface 26 of the inner ring 28, and the cage 30 and the outer ring 25 or the inner ring 28 are transmitted during torque transmission. A spherical force acts between the two, but the maximum value of the spherical force can be reduced and heat generation inside the joint can be suppressed. Further, the outer ring 25 has good workability by cold forging because the forging die can be easily pulled out, and the manufacturing cost can be reduced.

  The present applicant verifies the influence and tendency of the internal force consisting of the track load, the pocket load and the spherical force described above by making both the track grooves 22 and 27 of the outer ring 25 and the inner ring 28 into a tapered shape. By performing (FEM) analysis, the range of the taper angle α (see FIGS. 1 and 13) of the track grooves 22 and 27 was narrowed down and optimally set.

  First, the tendency of the internal force (track load, pocket load and spherical force) by increasing the taper angle α of the track grooves 22 and 27 is shown in Table 1. In Table 1, the phase at which the ball 29 is most likely to jump out (phase angle φ = 0 °) and the phase of the ball 29 at which the internal force reaches the maximum value, that is, the phase at which the ball 29 enters the deepest (phase angle φ = 180 ° vicinity) (see FIG. 2 and FIG. 14). The fluctuation range of the spherical force means a difference between the maximum value and the minimum value of the spherical force.

  As is apparent from the above table, when the taper angle α is increased, the maximum value of the pocket load is increased, but the wall thickness of the outer ring 25 is increased at the phase where the ball 29 is deepest (phase angle φ = 180 °), Further, since the strength can be ensured by increasing the cage offset amount to increase the cage wall thickness, there is no problem.

  Next, in order to determine the upper limit value of the taper angle α, a finite element method (FEM) analysis was performed. When the taper angle α is increased, the internal force (track load and pocket load) is reduced at the phase (phase angle φ = 0 °) at which the ball 29 is most likely to jump out, which is advantageous in terms of strength. Since it is the opening end 23 and the wall thickness becomes small, the tendency was confirmed by converting the stress value generated in the track groove 22 into the joint strength. The result is as shown in FIG. As apparent from the characteristics shown in the figure, since the joint angle is less than the required strength when the taper angle α is 12.9 °, the upper limit of the taper angle α is defined as 12 °.

  In the above-described embodiment, the case where the track offset is provided is illustrated, but the track offset amount F may be set to 0 without providing the track offset. That is, when the track offset is provided, the arc bottom 22a located on the back side of the outer ring 25 becomes shallow toward the back side, so that the ball located at the deepest part of the track groove 22 when the operating angle is taken. 29 rides may occur.

Therefore, the center of curvature O ₁ of the track groove 22 of the outer ring 25 is made to coincide with the center of curvature O ₄ of the inner spherical surface 21, and the center of curvature O ₂ of the track groove 27 of the inner ring 28 is made to be the center of curvature O _{3 of the} outer spherical surface 26. By making the track offset amount F equal to 0, the arc bottom 22a located on the back side of the outer ring 25 has a uniform depth without becoming shallow toward the back side, so the operating angle was taken. Occasionally, the ball 29 located at the innermost part of the track groove 22 can be prevented from climbing.

  The results of the internal force analysis performed by varying each factor of the track offset amount F, the cage offset amount f, and the taper angle α will be described below. Here, with respect to the track offset, the track offset amount F = 0, that is, “no track offset” is set in consideration of the characteristics of the ultra-high angle fixed type constant velocity universal joint in which the allowable load torque does not drop even when entering the high angle region. The cage offset should be as small as possible from the viewpoint of internal force. However, to ensure the function of the joint, a certain amount of cage offset must be provided, so that 0 ≦ f / PCR ≦ 0.150 is varied. It was. The taper angle α was varied in the range from 0 ° to 12 °.

  If the cage offset amount is f = 0 (f / PCR = 0), when the taper angle α is 1.1 ° or more, the track load and the pocket load at the phase (0 ° phase) at which the ball 29 is most likely to jump out are zero. become. On the other hand, if the taper angle α = 12 °, when the cage offset amount f = 3.94 (f / PCR = 0.114) or less, the track load of the phase (0 ° phase) at which the ball 29 is most likely to jump out and Pocket load is zero.

  That is, if the relationship between the cage offset amount f and the taper angle α is set within the hatched region in FIG. 16, the track load and pocket load at the phase (0 ° phase) at which the ball 29 is most likely to jump out are zero. Become. Here, FIG. 16 is drawn based on data calculated by internal force analysis, where the horizontal axis represents the taper angle α (deg) and the vertical axis represents f / PCR.

Thus, the internal specifications that are advantageous in a higher angle operating range are as follows, with the load applied to the phase (0 ° phase) at which the ball 29 is most likely to jump out minimized.
Track offset: None Cage offset amount f: 0 <f / PCR ≦ 0.12 (however, the operating angle is 0 °)
Taper angle α: 1 ° ≦ α ≦ 12 °

  Further, in this embodiment, the load at the phase (0 ° phase) where the ball 29 is most likely to jump out is reduced, while the peak load is larger than that of the conventional constant velocity universal joint. In order to ensure, it is preferable to arrange the thick portion of the cage 30 toward the opening end side of the outer ring 25.

  For the fixed type constant velocity universal joint according to the present invention (example) and the conventional fixed type constant velocity universal joint (comparative example) according to the present invention whose dimensions are set according to the above-described internal specifications, the phase at which the ball 29 is most likely to protrude (0 ° phase) When the track load and the pocket load in) were calculated, the results were as shown in FIG. From the figure, it can be seen that in the example, both the track load and the pocket load are reduced by 80% or more compared to the comparative example.

It is sectional drawing which shows embodiment of the fixed type constant velocity universal joint which concerns on this invention. In the constant velocity universal joint of FIG. 1, it is sectional drawing which shows the state which the inner ring took the maximum operating angle with respect to the outer ring. (A) is sectional drawing which shows the cage in the constant velocity universal joint of FIG. 1, (b) is sectional drawing which shows the cage in the conventional constant velocity universal joint. FIG. 4 is a left side view of the cage shown in FIG. FIG. 5 is a cross-sectional view of FIG. 4. FIG. 5 is a side view of the outer ring viewed from the opening side, for explaining a procedure for incorporating the cage into the outer ring. It is sectional drawing of the cage which shows embodiment which made the edge part of the spherical surface in a cage of a pocket the spherical surface R shape. It is sectional drawing of the cage which shows the embodiment which made the edge part of the spherical surface in a cage of a pocket, and the edge part of a cage outer spherical surface into the spherical surface R shape. FIG. 6 is a cross-sectional view of a cage showing an embodiment in which an edge portion on the inner spherical surface side of the pocket and an edge portion of the outer spherical surface of the pocket are formed into a spherical R shape, and the radius of curvature of the thin side corner of the pocket is larger than that of the thick side corner. is there. It is the elements on larger scale which show the thin wall side corner part and thick wall side corner part of a pocket. It is the elements on larger scale which show the case where the thin wall side corner part of a pocket is made into the minimum curvature radius. It is the elements on larger scale which show the case where the thin wall side corner part of a pocket is made into the maximum curvature radius. FIG. 2 is a diagram for explaining internal specifications such as a cage offset and a track offset in the constant velocity universal joint of FIG. 1. It is sectional drawing which shows the phase of the ball accommodated in the cage. It is a characteristic view which shows the relationship of the joint strength with respect to the taper angle of a track groove. It is a characteristic view which shows the relationship between the taper angle of a track groove, and f / PCR. It is a characteristic view which shows the 0 degree phase load at the time of a basic torque load. It is sectional drawing which shows the prior art example of a fixed type constant velocity universal joint. In the constant velocity universal joint of FIG. 18, it is sectional drawing which shows the state which the inner ring took the maximum operating angle with respect to the outer ring. (A) is the side view which looked at the outer ring | wheel of FIG. 18 from the opening side, (b) is sectional drawing which shows the cage of FIG.

Explanation of symbols

21 Inner spherical surface of outer joint member (outer ring) 22 Track groove of outer joint member (outer ring) 23 Open end 25 Outer joint member (outer ring)
26 Outer spherical surface of inner joint member (inner ring) 27 Track groove of inner joint member (inner ring) 28 Inner joint member (inner ring)
29 Ball 30 Cage 31 Cage inner spherical surface 32 Cage outer spherical surface 33 Pocket 34 Tapered surface 35, 36 Edge portion 37 Thin side corner portion 38 Thick side corner portion 40 Cut portion (cut surface)
f Cage offset amount F Track offset amount O ₁ Center of curvature of track groove of outer joint member (outer ring) O ₂ Center of curvature of track groove of inner joint member (inner ring) O ₃ Center of inner spherical surface of cage O ₄ Center of outer spherical surface of cage ₄ α Tapered angle of track groove θ / 2 Tapered angle of opening side end of inner spherical surface of cage φd ₁ Outer diameter of cage φD ₁ Inner diameter of outer ring

Claims (8)

An outer joint member in which a plurality of track grooves are formed on the inner spherical surface at equal intervals in the circumferential direction toward the opening end along the axial direction, and a plurality of track grooves that are paired with the track grooves of the outer joint member are formed on the outer spherical surface. An inner joint member formed along the axial direction at equal intervals in the circumferential direction, a plurality of balls that are interposed between both track grooves of the outer joint member and the inner joint member, and an inner spherical surface of the outer joint member And a cage having a pocket interposed between the outer spherical surface of the inner joint member and holding the ball,
The outer side groove bottom of the track groove of the outer joint member has a tapered shape linearly expanded toward the opening end, and the inner side groove bottom of the track groove of the inner joint member faces the inner end. The taper is linearly expanded in diameter,
The outer spherical center and the inner spherical center of the cage are offset to the opposite side by an equal distance in the axial direction with respect to the joint center, and 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 by the amount of cage offset with respect to the joint center,
The outer spherical surface located on the opening end side of at least two opposing pockets of the cage is partially cut, and the outer diameter of the cage at the cut portion is set smaller than the inner diameter of the outer joint member. Fixed constant velocity universal joint.   2. A tapered shape in which an opening-side end portion of the outer spherical surface of the cage extends in the axial direction and an opening-side end portion of the inner spherical surface of the cage expands toward the opening-side end portion of the outer spherical surface. Fixed type constant velocity universal joint described in 1.   The fixed type constant velocity universal joint according to claim 2, wherein a taper angle of an opening side end portion of the inner spherical surface of the cage is set to be not less than half of a maximum operating angle formed by the outer joint member and the inner joint member.   The edge part of the cage inner spherical surface side or the cage outer spherical surface side of the pocket that is formed along the circumferential direction of the cage and accommodates the ball has a spherical R shape. Fixed type constant velocity universal joint as described in any one of Claims.   The radius of curvature of the thin side corner of the pocket that accommodates the ball is formed along the circumferential direction of the cage, and is set larger than the radius of curvature of the thick side corner and smaller than the radius of the ball. The fixed type constant velocity universal joint as described in any one of Claims 1-4.   The fixed type constant velocity universal joint according to any one of claims 1 to 5, wherein an upper limit value of a taper angle of both track grooves of the outer joint member and the inner joint member is 12 °.   The cage offset amount f between the outer spherical center and the inner spherical center of the cage is connected to the center of curvature of the track groove of the outer joint member or the center of curvature of the track groove of the inner joint member and the center of the ball when the operating angle is 0 °. The fixed type constant velocity universal joint according to any one of claims 1 to 6, wherein a value f / PCR of a ratio with the length PCR of the line segment is larger than 0 and 0.12 or less.   The fixed type constant velocity universal joint according to any one of claims 1 to 7, wherein a thick side of the cage is positioned on an opening end side of the outer joint member.

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