JP2007064264A - Fixed type constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance operability of a cage at the time of inputting a high operation angle/high torque and preventing strength from lowering, in a constant velocity universal joint for a high angle with a track groove of an outer ring tapered by linearly expanding its diameter toward an opening end. <P>SOLUTION: In the fixed type constant velocity universal joint provided with the outer ring 25 having the plurality of track grooves 22 formed at equal circumferential intervals in an inner spherical surface 21 along an axial direction toward the opening end 23, an inner ring 28 having a plurality of track grooves 27, making pairs with the track grooves 22 of the outer ring 25, formed at equal circumferential intervals in an outer spherical surface 26 along the axial direction, a plurality of balls 29, interposed between the track grooves 22, 27 of the outer ring 25 and the inner ring 28, for transmitting torque and a cage 30 for holding the balls 29 while being interposed between the inner spherical surface 21 of the outer ring 25 and the outer spherical surface 26 of the inner ring 28, a boundary part 35 of the inner spherical surface part 21 of the outer ring 25 and a mouse bottom part 34 is formed as a rounded surface respectively tangentially contacted with the inner spherical surface part 21 and the mouse bottom part 34 at tangent lines. <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.

  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 rotational torque can be transmitted at a constant speed even if the two shafts have an operating angle.

  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.

  In general, the fixed type constant velocity universal joint has an outer surface in which a plurality of track grooves 2 are formed on the inner spherical surface portion 1 at equal intervals in the circumferential direction toward the mouth opening end 3 as shown in FIG. An outer ring 5 as a joint member, and an inner ring 8 as an inner joint member in which a plurality of track grooves 7 paired with the track grooves 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; A plurality of balls 9 are interposed between the track groove 2 of the outer ring 5 and the track groove 7 of the inner ring 8 to transmit torque, and are interposed between the inner spherical surface portion 1 of the outer ring 5 and the outer spherical surface 6 of the inner ring 8. And a cage 10 for holding the ball 9.

  When this constant velocity universal joint is used for a drive shaft of an automobile, the outer ring 5 is connected to the driven shaft, and the drive shaft extending from the sliding type constant velocity universal joint attached to the inner ring 8 on the differential on the vehicle body side is spline-fitted. The structure is connected with. In this constant velocity universal joint, when an operating angle is given between the outer ring 5 and the inner ring 8, the ball 9 accommodated in the cage 10 is always within the bisector of the operating angle at any operating angle. This maintains the constant velocity of the joint.

As a fixed type constant velocity universal joint for the above-described needs for increasing the angle, the mouth opening side groove bottom of the track groove 2 of the outer ring 5 is tapered so as to linearly expand toward the mouth opening end 3 of the outer ring 5. At the same time, by making the mouse groove opposite to the mouth side of the track groove 7 of the inner ring 8, that is, the mouse bottom side groove bottom, into a tapered shape (taper angle α in the figure) linearly expanding toward the mouse bottom of the inner ring 8. The operation in the high angle region is realized (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 constant angle universal joint having a high angle described above, the mouth opening side groove bottom of the track groove 2 of the outer ring 5 has a tapered shape linearly expanding toward the mouth opening end 3 of the outer ring 5, The thickness of the outer ring 5 in the vicinity of the opening end of the mouse is thinner than other parts.

  Further, the inner spherical surface portion 1 of the outer ring 5 is formed by forging or turning, subjected to a curing process by heat treatment, and then finished by finishing. The boundary portion 11 between the inner spherical surface portion 1 and the mouse bottom portion 4 of the outer ring 5 finished in this way is square.

  In view of the above, when the constant velocity universal joint (outer ring 5 and inner ring 8) takes a high operating angle as shown in FIG. 7, the ball 9 that is in a phase that is most likely to jump out from the mouth opening end 3 of the outer ring 5 is When the outer opening 5 of the outer ring 5 is closest to the mouse opening end 3 and a rotational torque is applied in this state, the wall thickness in the vicinity of the opening end of the outer ring 5 becomes thinner than other parts. Is easily deformed, and the cage 10 having relatively small rigidity is elastically deformed.

  Accordingly, as shown in FIG. 8, the rectangular boundary portion 11 between the inner spherical surface portion 1 of the outer ring 5 and the bottom portion 4 of the mouse bites into the outer spherical surface 12 of the cage 10 that is in sliding contact with the inner spherical surface portion 1 of the outer ring 5. (Part indicated by a dot-and-dash circle in the figure), the operability of the cage 10 is deteriorated, and the cage 10 is damaged and the strength is lowered. In FIG. 8, the inner ring 8 and the ball 9 are not shown.

  Therefore, the present invention has been proposed in view of the above-described problems, and the object of the present invention is to increase the angle of the outer ring track groove by increasing the diameter linearly toward the mouth opening end. In the constant velocity universal joint, the operability of the cage is improved at the time of inputting a high operating angle and high torque, and the strength is prevented from being lowered.

  As technical means for achieving the above-mentioned object, the present invention includes an outer joint member in which a plurality of track grooves are formed in the inner spherical surface portion at equal intervals in the circumferential direction toward the mouth opening end along the axial direction; An inner joint member in which a plurality of track grooves paired with track grooves of the outer joint member are formed in the outer spherical surface portion along the axial direction at equal intervals in the circumferential direction, and both track grooves of the outer joint member and the inner joint member Fixed type constant velocity with a plurality of balls interposed between them to transmit torque and a cage for holding the balls interposed between the inner spherical surface portion of the outer joint member and the outer spherical surface portion of the inner joint member In the joint, a boundary portion between the inner spherical surface portion and the mouth bottom portion of the outer joint member is formed into an R curved surface that is connected to at least the inner spherical surface portion by a tangent line.

  Here, “the boundary portion is connected to at least the inner spherical surface portion thereof by a tangent” means that the boundary portion formed in the R curved surface only needs to be connected to the inner spherical surface portion of the outer joint member by a tangent line. It means that it does not necessarily have to be connected to the bottom part by a tangent line. If the boundary portion described above is connected to only the inner spherical surface portion of the outer joint member by a tangent line, it is possible to achieve the above-described purpose only by changing the shape of the inner spherical surface portion during finishing. .

  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.

  To increase the angle of the fixed type constant velocity universal joint, the track groove of the outer joint member is linearly enlarged toward the mouth opening end, and the track groove of the inner joint member is directed to the opposite opening end. The outer spherical center and 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 is A structure in which the center of curvature of the track groove of the inner joint member is offset from the joint center by a cage offset amount is employed.

  In the fixed type constant velocity universal joint that achieves this high angle, the outer joint member has a taper shape in which the track groove is linearly expanded toward the mouth opening end, so that the vicinity of the mouth opening end of the outer joint member The wall thickness is thinner than other parts. In this constant velocity universal joint, when the rotational torque is applied with the ball in the phase that is most likely to jump out of the mouth opening end of the outer joint member at the high operating angle, when the rotational torque is applied in the state of being closest to the mouse opening end, Since the thickness in the vicinity of the mouth opening end of the member is thinner than other parts, the outer joint member is easily deformed, and the cage having relatively small rigidity is elastically deformed.

  Therefore, for a fixed type constant velocity universal joint with an increased angle, a means for forming a boundary surface between the inner spherical surface portion of the outer joint member and the bottom of the mouse into an R curved surface connected at least with the inner spherical surface portion should be provided. However, even if the outer joint member or cage is deformed at the time of high operating angle and high torque input, the aforementioned boundary portion will not bite into the outer spherical surface of the cage, so it is effective in improving the operability of the cage and maintaining the strength. It is.

  In this outer joint member, the boundary portion formed by the R curved surface and the inner spherical surface portion can be simultaneously formed by grinding. If it does in this way, in manufacturing an outer joint member, processing time can be shortened and workability can be improved.

  Further, this boundary portion is formed in advance into an R curved surface connected at least to the inner spherical surface portion before finishing the inner spherical surface portion so that the finished shape can pass through the R curved surface when finishing the inner spherical surface portion. It is also possible to prevent the boundary portion between the inner spherical surface portion of the finished shape and the R curved surface from becoming sharp. By doing so, the corner of the boundary portion becomes dull, and the boundary portion does not bite into the outer spherical surface of the cage.

  In addition, when both the track grooves of the outer joint member and the inner joint member are tapered, 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 wall thickness is reduced, the influence and tendency of the track groove being tapered in the internal specifications of this fixed type constant velocity universal joint As a result of the verification, the upper limit value was defined as 12 ° as the optimum value of the taper angle of the track groove.

  According to the present invention, the boundary portion between the inner spherical surface portion of the outer joint member and the bottom of the mouse is formed into an R-curved surface that is connected to at least the inner spherical surface portion by a tangent line. Or, even if the cage is deformed, the aforementioned boundary portion does not bite into the outer spherical surface of the cage, so the operability of the cage can be improved even when a high operating angle and torque are input, and the strength of the cage is reduced. Can also be suppressed. In particular, this effect is remarkable for a high-angle constant velocity universal joint having a tapered shape in which the track groove of the outer joint member is linearly expanded toward the mouth opening end.

  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. 4 has an outer portion having a mouth portion 24 in which a plurality of track grooves 22 are formed in the inner spherical surface portion 21 at equal intervals in the circumferential direction toward the mouth opening end 23 along the axial direction. An outer ring 25 that is a joint member, and 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 in the outer spherical surface 26 along the axial direction at equal intervals in the circumferential direction; A plurality of balls 29 are provided between the track grooves 22 of the outer ring 25 and the track grooves 27 of the inner ring 28 to transmit torque, and are interposed between the inner spherical surface portion 21 of the outer ring 25 and the outer spherical surface 26 of the inner ring 28. And a cage 30 for holding a ball 29. 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 the stem portion integrally extending from the mouse portion 24 of the outer ring 25, and a drive shaft (not shown) is coupled to the inner ring 28 by spline fitting. The structure is such that torque can be transmitted while allowing the operating angle displacement between the driven shaft and the drive shaft. In this constant velocity universal joint, when the outer ring 25 and the inner ring 28 are angularly displaced, the ball 29 accommodated in the pocket 33 of the cage 30 is always maintained within the bisector of the operating angle at any operating angle, The constant velocity of the joint is ensured.

  This constant velocity universal joint has a taper shape in which each track groove 22 of the outer ring 25 is linearly expanded toward the mouth opening end 23 of the outer ring 25 in order to have a structure capable of obtaining a large operating angle. In other words, the track groove 22 has a circular arc bottom 22a on the mouse bottom side that is opposite to the opening side and a tapered bottom 22b on the mouse opening side. On the other hand, each track groove 27 of the inner ring 28 is also tapered so as to linearly expand toward the opposite opening end of the outer ring 25. That is, the track groove 27 has an arc bottom 27a on the mouse opening side and a tapered bottom 27b on the mouse bottom side.

Further, 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 passing through the joint center O. (Cage offset). 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 located at the center of curvature of the inner spherical surface portion 21 of the outer ring 25 and the center of curvature of the outer spherical surface 26 of the inner ring 28. are each identical, the center of curvature of the outer spherical surface 26 of the center of curvature and the inner ring 28 of the inner spherical surface portion 21 of the outer ring 25, the center of curvature O ₄ and the curvature center O ₃ of the inner spherical surface 31 thereof outer spherical surface 32 of the cage 30 (Accordingly, in the following description, the center of curvature of the inner spherical surface portion 21 of the outer ring 25 is also O _4, and the center of curvature of the outer spherical surface 26 of the inner ring 28 is also O ₃ ).

  In this way, with respect to the fixed type constant velocity universal joint with an increased angle, as shown in FIG. 1, the boundary portion 35 between the inner spherical surface portion 21 and the mouse bottom portion 34 of the outer ring 25 is changed to the inner spherical surface portion 21 and the mouse bottom portion 34. And R curved surfaces connected by tangent lines. Note that FIG. 1 also shows an enlarged view of the portion A, and in the enlarged view, a conventional square boundary portion is indicated by a broken line.

  In the fixed type constant velocity universal joint that realizes a high angle, the track groove 22 of the outer ring 25 is formed into a tapered shape linearly expanding toward the mouth opening end 23, so that the thickness near the opening end of the outer ring 25 is increased. However, unlike the conventional case, the boundary portion 35 between the inner spherical surface portion 21 and the mouse bottom portion 34 of the outer ring 25 is not angular, so that the outer ring is at the time of high operating angle / high torque input. 25 or the cage 30 is deformed, the boundary portion 35 does not bite into the outer spherical surface 32 of the cage 30, which is effective in improving the operability and maintaining the strength of the cage 30.

  That is, in the constant velocity universal joint of this embodiment, as shown in FIG. 5, at the maximum operating angle, the ball 29 that is in a phase that is most likely to jump out from the mouse opening end 23 of the outer ring 25 comes closest to the mouse opening end 23. When a rotational torque is applied in this state, the thickness of the outer ring 25 in the vicinity of the opening end is thinner than that of other parts, so that the outer ring 25 is easily deformed and has relatively low rigidity. Although the cage 30 is elastically deformed, even if the outer ring 25 or the cage 30 is deformed when a high operating angle / high torque is input, the boundary 35 between the inner spherical surface portion 21 of the outer ring 25 and the mouse bottom 34 becomes an R curved surface. Since it is molded and not angular, the boundary portion 35 does not bite into the outer spherical surface 32 of the cage 30, so that the operability of the cage 30 and the strength can be maintained.

  Here, as shown in FIG. 2, the boundary portion 36 formed into an R-curved surface only needs to be connected to the inner spherical surface portion 21 of the outer ring 25 by a tangent line, and may not necessarily be connected to the mouse bottom portion 34 by a tangent line. If the boundary portion 36 is connected to only the inner spherical surface portion 21 of the outer ring 25 by a tangent line, it is only necessary to change the shape of the inner spherical surface portion 21 during finishing. Note that FIG. 2 also shows an enlarged view of a portion B, and a conventional square boundary portion is shown by a broken line in the enlarged view.

  Further, as shown in FIG. 3, the boundary portion 37 is formed in advance into an R curved surface connected to the inner spherical surface portion 21 of the outer ring 25 and the mouse bottom portion 34 before the inner spherical surface portion 21 is finished. It is possible to prevent the boundary portion 37 between the finished inner spherical surface portion 21 and the R curved surface from being sharpened by processing the finished shape so as to pass through the R curved surface when the spherical surface portion 21 is finished. By doing so, the corners of the boundary portion 37 become dull, so that the boundary portion 37 does not bite into the outer spherical surface 32 of the cage 30.

In the embodiment of FIGS. 1 to 3, when the boundary position between the boundary portions 35 to 37 and the inner spherical surface portion 21 comes close to the center of curvature O ₄ of the inner spherical surface portion 21 of the outer ring 25, the contact with the outer spherical surface 32 of the cage 30. Since the angle θ (see FIGS. 1 to 3) is reduced and the function is lowered, it is desirable to set the boundary position between the boundary parts 35 to 37 and the inner spherical surface part 21 to the extent that the function is not lowered.

  When the track grooves 22 and 27 of the outer ring 25 and the inner ring 28 are tapered, it is possible to easily increase the operating angle without increasing the outer diameter of the outer ring 25. Among the internal specifications of this fixed type constant velocity universal joint, the influence of the internal force consisting of the track load, the pocket load and the spherical force is selected so as not to deteriorate the strength and workability of the outer ring 25 even if the thickness is reduced. By verifying the tendency and performing a finite element method (FEM) analysis, the range of the taper angle α of the track grooves 22 and 27 was narrowed down, and the upper limit value was defined as 12 ° as an optimum value.

  First, when the taper angle α is increased, the maximum value of the pocket load is increased. However, the wall thickness of the outer ring 25 is increased at the phase where the ball 29 is deepest, and the cage offset amount is increased to increase the cage thickness. It is not a problem because the strength can be secured by increasing the size.

  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 in the phase in which the ball 29 is most likely to jump (see FIG. 5), which is advantageous in terms of strength, but the open end 23 of the outer ring 25 is improved. Since the thickness is small, the stress value generated in the track groove 22 is converted into the joint strength to confirm the tendency. As a result, the taper angle α is 12.9 °, and the joint strength is lower than the required strength. Therefore, the upper limit value is defined as 12 ° as the optimum range of the taper angle α.

  In the above-described embodiment, the track groove 22 of the outer ring 25 has a tapered shape linearly expanded toward the mouth opening end 23 and the track groove 27 of the inner ring 28 linearly expands toward the opposite opening end. The outer spherical center and inner spherical center of the cage 30 are offset to the opposite side in the axial direction by an equal distance from the joint center, and the center of curvature of the track groove 22 of the outer ring 25 and the track groove of the inner ring are formed. However, the present invention is not limited to this and other fixed types are described. It can also be applied to constant velocity universal joints.

In embodiment of the fixed type constant velocity universal joint which concerns on this invention, it is sectional drawing which shows the lower half and outer part A part of an outer ring. In other embodiment of this invention, it is sectional drawing which shows the lower half of an outer ring | wheel, and B part enlarged part. In other embodiment of this invention, it is sectional drawing which shows the lower half of an outer ring | wheel, and the C section enlarged part. In embodiment of this invention, it is sectional drawing which shows the whole structure of a fixed type constant velocity universal joint. It is sectional drawing which shows the state which the constant velocity universal joint of FIG. 4 took the maximum operating angle. It is sectional drawing which shows the prior art example of a fixed type constant velocity universal joint. It is sectional drawing which shows the state which the constant velocity universal joint of FIG. 6 took the maximum operating angle. FIG. 7 is a perspective view including a part of the constant velocity universal joint of FIG. 6 including a partially omitted portion showing a state where the maximum operating angle is taken (the inner ring and the ball are not shown).

Explanation of symbols

21 Inner spherical surface portion of outer joint member (outer ring) 22 Track groove of outer joint member (outer ring) 23 Mouse opening 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 sphere 32 Cage outer sphere 34 Mouse bottom 35-37 Boundary 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 taper angle of the outer spherical surface center α track grooves of the inner spherical surface center O ₄ cages of the cage

Claims (5)

  A plurality of track joints formed on the inner spherical surface with a plurality of track grooves formed at equal intervals in the circumferential direction along the axial direction toward the mouth opening end, and a plurality of pairs formed on the outer spherical surface and the track grooves of the outer joint member. An inner joint member having track grooves 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 outer joint member A fixed type constant velocity universal joint having a cage for holding a ball interposed between the inner spherical surface portion of the inner joint member and the outer spherical surface portion of the inner joint member, and a boundary between the inner spherical surface portion of the outer joint member and the bottom of the mouse A fixed type constant velocity universal joint, characterized in that the portion is formed into an R curved surface connected to at least the inner spherical surface portion by a tangent line.   The fixed type constant velocity universal joint according to claim 1, wherein the boundary portion and the inner spherical surface portion formed by the R curved surface are simultaneously formed by grinding.   Before finishing the inner spherical surface portion, the boundary portion between the inner spherical surface portion of the outer joint member and the bottom of the mouse is formed into an R curved surface connected to at least the inner spherical surface portion at the time of finishing the inner spherical surface portion. The fixed type constant velocity universal joint according to claim 1, wherein the finished shape is processed so as to pass through the R-curved surface so that a boundary portion between the inner spherical surface portion of the finished shape and the R-curved surface is not sharpened.   The track groove of the outer joint member has a taper shape linearly expanded toward the opening end, and the track groove of the inner joint member has a taper shape linearly expanded toward the opposite opening end, The outer spherical center and inner spherical center of the cage are offset to the opposite side in the axial direction by an equal distance from 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 jointed. The fixed type constant velocity universal joint according to claim 1, wherein the fixed type constant velocity universal joint is offset from the center by a cage offset amount.   The fixed type constant velocity universal joint according to any one of claims 1 to 4, 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 °.

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