JP2006266329A - Fixed type constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily actualize a higher operating angle without degrading the strength and machining efficiency of a joint by specifying a taper angle between both track grooves of an outer ring and an inner ring. <P>SOLUTION: This 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 at circumferentially equal spaces toward an opening end 23 along the axial direction, the inner ring 28 having a plurality of track grooves 27 paired with the track grooves 22 of the outer ring 25 and formed in an outer spherical face 26 at circumferentially equal spaces along the axial direction, a plurality of balls 29 laid between both track grooves 22, 27 of the outer ring 25 and the inner ring 28 for transmitting torque, and a cage 30 laid between the inner spherical face 21 of the outer ring 25 and the outer spherical face 26 of the inner ring 28 for holding the balls 29. The track groove 22 of the outer ring 25 has a opening side groove bottom tapered with its diameter enlarged linearly toward the opening end 23. The track groove 27 of the inner ring 28 has a corner side groove bottom tapered with its diameter enlarged linearly toward a corner end. Both track grooves 22, 27 of the outer ring 25 and the inner ring 28 have taper angles of 0-12°. <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 improving the collision safety of automobiles, but in order to prevent the turning radius of the vehicle from increasing accordingly, the fixing used as a coupling joint for automobile drive shafts, etc. There is a need to increase the steering angle of the front wheels by increasing the angle of the constant velocity universal joint.

  Generally, the fixed type constant velocity universal joint includes 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 the outer joint member is disposed on the outer spherical surface. Torque is transmitted by interposing an inner joint member that is formed along the axial direction at equal intervals in the circumferential direction and between the track grooves of the outer joint member and the inner joint member. And a cage for holding the balls interposed between the inner spherical surface of the outer joint member and the outer spherical surface of the inner joint member.

As the fixed type constant velocity universal joint for the above-mentioned needs for increasing the angle, the opening side groove bottom of the track groove of the outer joint member is tapered so as to linearly expand toward the opening end, and the inner joint member The track groove has a taper shape in which the diameter of the inner side of the track groove is linearly expanded toward the inner end of the track groove, thereby realizing an operation in a high angle region (see, for example, Patent Documents 1 to 3).
JP 2001-153149 A JP 2001-304282 A JP 2001-349332 A

  By the way, in the past, in the fixed type constant velocity universal joint aiming at increasing the angle, there has been no special consideration for defining the taper angle of both track grooves of the outer joint member and the inner joint member. is there.

  In the fixed type constant velocity universal joint disclosed in each of Patent Documents 1 to 3 described above, it is easy to increase the operating angle by making both track grooves of the outer joint member and the inner joint member into a tapered shape. When the outer diameter of the outer joint member is regulated and the outer diameter of the outer joint member is regulated, if the taper of the track groove is further added, the thickness of the outer joint member becomes thinner and the strength of the outer joint member is reduced. It will be.

  Therefore, the present invention has been proposed in view of the above-mentioned problems, and the object of the present invention is to provide strength of the constant velocity universal joint by defining the taper angles of both track grooves of the outer joint member and the inner joint member. It is another object of the present invention to provide a fixed type constant velocity universal joint that can easily increase the operating angle without reducing workability.

  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. An inner joint member in which a plurality of track grooves paired with the track grooves of the outer joint member are formed along the axial direction at equal intervals in the circumferential direction; and between the track grooves of the outer joint member and the inner joint member. A plurality of balls for transmitting torque and a cage for holding the balls 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 Is fixed in a taper shape in which the diameter of the inner side of the track groove of the inner joint member is linearly expanded toward the inner end. Type constant velocity universal joint, said outer side The upper limit of the taper angle of both track grooves of the hand member and the inner joint member, characterized in that the 12 °.

  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 outer spherical center and the inner spherical center of the cage are offset to the opposite side in the axial direction with respect to the joint center plane, and the cage offset amount is offset from the opening end of the outer joint member. It is desirable to set the ball so that it can be restrained by the pocket of the cage.

  Here, by setting the cage offset amount large, there is an advantage that the thickness can be improved by increasing the wall thickness on the inlet side of the cage into which the inner joint member is incorporated. In addition, since the wall thickness on the entrance side of the cage can be increased, it is possible to restrain the ball from popping out from the open end of the outer joint member by the cage pocket when the operating angle is taken.

  However, if the cage offset amount is too large, the circumferential movement amount of the ball in the cage pocket becomes large, and in order to ensure proper movement of the ball, it is necessary to increase the circumferential dimension of the cage pocket. The pillar portion of the cage becomes thinner and the strength is 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 is excessive, and there exists an optimum range in which the significance of providing the cage offset amount can be balanced with the above-described problems in strength. However, since the optimum range of the cage offset varies depending on the size of the joint, it needs to be obtained 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 in the above-described configuration is the length PCR of the line segment connecting 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. It is desirable that the ratio f / PCR is set to be in the range of 0.018 to 0.150.

  If this ratio f / PCR is larger than 0.150, there is a problem in the aforementioned strength. On the contrary, if it is smaller than 0.018, the significance of providing the cage offset amount f is lost. That is, the purpose of the cage offset is to prevent the contact point on the outer joint member entrance side of the ball from protruding from the pocket of the cage at a high operating angle. Therefore, from the viewpoint of securing cage strength and durability, the optimum range of the cage offset amount f is that the ratio f / PCR is within the range of 0.018 to 0.150.

  In the above-described configuration, 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 plane, and the center of curvature of the track groove of the outer joint member; It is desirable that the track offset amount is zero because the track is offset to the opposite side by the cage offset amount with respect to the curvature center plane of the track groove of the inner joint member.

  There is an offset between the center of curvature of the inner spherical surface of the outer joint member and the center of curvature of the track groove, and similarly there is an offset between the center of curvature of the outer spherical surface of the inner joint member and the center of curvature of the track groove. Then, since the track groove becomes shallower toward the back side of the outer joint member, there is a possibility that the ball located at the innermost part of the track groove may run up when the operating angle is taken. Therefore, by setting the track offset amount to 0, the track groove does not become shallow on the back side of the outer joint member, so that it is possible to suppress the climbing of the ball located at the innermost part of the track groove when the operating angle is taken. can do.

  Furthermore, in the above-described configuration, it is desirable that both the track grooves of the outer joint member and the inner joint member are finish-formed by cold forging.

  Thus, by forming the tapered track groove by cold forging, the forging die can be easily pulled out, so that the workability of cold forging is good and the manufacturing cost can be reduced.

  According to the present invention, by defining the upper limit value of the taper angle of both track grooves of the outer joint member and the inner joint member within the optimum range of 12 °, without reducing the strength and workability of the constant velocity universal joint, The operating angle can be easily increased, and the steering angle of the front wheels has been increased to prevent the vehicle turning radius from increasing in response to the demand for a longer wheelbase from the standpoint of improving automobile crash safety in recent years. It can be easily achieved.

  Embodiments of the 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. And a plurality of balls 29 that transmit torque between the track grooves 22 and 27 of the inner ring 28 and between the inner spherical surface 21 of the outer ring 25 and the outer spherical surface 26 of the inner ring 28 to hold the balls 29. And a cage 30 to be operated. 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-side rotation shaft (not shown) is connected to a stem portion (not shown) extending integrally from the mouse portion 24 of the outer ring 25 described above, and a drive-side rotation shaft (not shown) is connected to the inner ring 28. Are coupled by serration or the like, so that a torque can be transmitted while allowing an operating angle displacement between the two rotating shafts.

  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 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 θ is 0 °, and FIG. 3 shows a state where the operating angle θ is the maximum angle. The operating angle θ 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 a certain operating angle θ other than 0 °, a plane perpendicular to the bisector of the angle θ formed by both the rotation axes X and Y is joined. This is referred to as a center 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. 2 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 of this embodiment, 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 the ball so that a large operating angle can be obtained. Is offset in the axial direction by an equal distance F with respect to the joint center plane P including (track offset). Similarly, 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 offset in the axial direction by an equal distance f with respect to the joint center plane P (cage). offset). The center of curvature of the outer spherical surface 26 of the inner ring 28 and the center of curvature of the inner spherical surface 21 of the outer ring 25 coincide with the centers of curvature O ₃ and O ₄ of the inner and outer spherical surfaces 31 and 32 of the cage 30, respectively.

  Thus, the pair of track grooves 22 and 27 form a wedge-shaped ball track in which the radial interval gradually increases from the back side of the outer ring 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. It receives the action of the axial force that tries to move in the direction.

When the outer ring 25 and the inner ring 28 take the maximum operating angle θmax, 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 f, centroid radius value of the ball 29, i.e., the center O ₅ of the curvature center O ₂ and the ball 29 of the track grooves 27 of the center of curvature O ₁ or the inner ring 28 of the track grooves 22 of the outer race 25 When the length of the connecting line segment is PCR, f / PCR = 0.018 to 0.150.

  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. 3 and 4) 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 loads 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, so that the cage 30 and the outer ring 25 or the inner ring 28 are communicated. 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. Furthermore, since the forging die can be easily pulled out, the workability by cold forging is good, and the manufacturing cost can be reduced.

  The present applicant verifies the influence and tendency of the internal force composed 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, and the finite element method. By carrying out (FEM) analysis, the range of the taper angle α 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 as shown in the table below. In the table below, 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 is maximum, that is, the phase at which the ball 29 is deepest (phase angle φ = Around 180 °). 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 an open end and its thickness becomes small, the stress value generated in the track groove 22 was converted into joint strength, and the tendency was confirmed. 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 present invention is not limited to this, and the track offset may be set to 0 by matching the track offset with the cage offset. That is, if the track offset amount is not 0, 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, by setting the track offset amount to 0, the arc bottom 22a located on the back side of the outer ring 25 does not become shallow toward the back side and has a uniform depth. Riding of the ball 29 located at the innermost part of the groove 22 can be suppressed.

It is sectional drawing which shows embodiment of the fixed type constant velocity universal joint which concerns on this invention. 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. 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. 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.

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 f Cage offset amount F Track offset amount O ₁ Center of curvature of track groove of outer joint member (outer ring) O ₂ Track groove of inner joint member (inner ring) the outer spherical surface center α taper angle of the inner spherical surface center O ₄ cages center of curvature O ₃ cages

Claims (5)

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 for holding a ball interposed between the outer joint and the outer spherical surface of the inner joint member, and a taper shape in which the opening side groove bottom of the track groove of the outer joint member is linearly expanded toward the opening end. And a fixed type constant velocity universal joint having a tapered shape in which the diameter of the inner side of the track groove of the inner joint member is linearly expanded toward the inner end thereof,
A fixed type constant velocity universal joint, 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 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 plane, and the cage offset amount causes the ball to protrude from the open end of the outer joint member. The fixed type constant velocity universal joint according to claim 1, wherein the fixed type constant velocity universal joint is set so as to be constrained by a pocket of the cage.   The outer spherical center and the inner spherical center of the cage are offset to the opposite side in the axial direction by an equal distance from the joint center plane, and the cage offset amount f and the center of curvature of the track groove of the outer joint member or the inner side The fixed mold according to claim 1 or 2, wherein a ratio f / PCR of a length PCR of a line segment connecting the center of curvature of the track groove of the joint member and the center of the ball is within a range of 0.018 to 0.150. Constant velocity universal joint.   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 plane, the center of curvature of the track groove of the outer joint member, and the track of the inner joint member 3. The fixed type constant velocity universal joint according to claim 1, wherein the center of curvature of the groove is offset to the opposite side by a cage offset amount with respect to the joint center plane including the ball center, and the track offset amount is zero.   The fixed type constant velocity universal joint according to any one of claims 1 to 4, wherein both track grooves of the outer joint member and the inner joint member are finish-formed by cold forging.

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