JP4745186B2 - Fixed constant velocity universal joint - Google Patents

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 automobiles, but in order to prevent the vehicle turning radius from increasing accordingly, the fixed type 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, this constant velocity universal joint is an outer joint member in which a plurality of track grooves 114 are formed on an inner spherical surface 112 at equal intervals in the circumferential direction toward the opening end 118 as shown in FIG. Of the outer ring 110, an inner ring 120 as an inner joint member in which a plurality of track grooves 124 paired with the track grooves 114 of the outer ring 110 are formed on the outer spherical surface 122 along the axial direction at equal intervals in the circumferential direction, A plurality of balls 130 that transmit torque by being interposed between the track groove 114 and the track groove 124 of the inner ring 120, and a ball 130 that is interposed between the inner spherical surface 112 of the outer ring 110 and the outer spherical surface 122 of the inner ring 120. The cage 140 to hold | maintain is provided.

Since the constant velocity universal joint for the above-mentioned needs for increasing the angle has a structure capable of obtaining a large operating angle, the center of curvature O ₃ of the inner spherical surface 144 of the cage 140 and the center of curvature O of the outer spherical surface 142 are shown in FIG. ₄ is offset in the axial direction opposite to the joint center plane P by an equal distance f (cage offset). Thus, by providing the cage offset, the cage 140 has a shape that is thick toward the opening side of the outer ring 110 and thin toward the back side.

Further, the center of curvature O ₁ of the track groove 114 of the outer ring 110 and the center of curvature O ₂ of the track groove 124 of the inner ring 120 are the center of curvature O ₄ of the inner spherical surface 112 of the outer ring 110 and the center of curvature O ₃ of the outer spherical surface 122 of the inner ring 120. Are offset in the opposite axial direction by an equal distance F (track offset). Thus, by providing the track offset, each of the track groove 114 of the outer ring 110 and the track groove 124 of the inner ring 120 is deep on the opening side of the outer ring 110 and shallow on the back side thereof. The pair of track grooves 114 and 124 form a wedge-shaped ball track in which the radial interval gradually increases from the back side of the outer ring 110 toward the opening side.

Note that the center of curvature O ₃ of the outer spherical surface 122 of the inner ring 120 coincides with the center of curvature of the inner spherical surface 144 of the cage 140, and the center of curvature O ₄ of the inner spherical surface 112 of the outer ring 110 is the center of curvature of the outer spherical surface 142 of the cage 140. Is consistent with

  In this fixed type constant velocity universal joint, in order to further increase the angle, the opening-side groove bottom of the track groove 114 of the outer ring 110 is tapered so as to linearly expand toward the opening side of the outer ring 110, and the inner ring The operation of the high angle region is realized by forming the back groove bottom of the 120 track grooves 124 into a tapered shape linearly expanding toward the back side of the inner ring 120 (for example, Patent Documents 1 to 3). reference).

  FIG. 13 shows a state in which the joint has a maximum operating angle θ, that is, the rotation axis X of the outer ring 110 and the rotation axis Y of the inner ring 120 (the central axis of the shaft 150 connected to the inner ring 120) have the maximum operating angle θ. Indicates the state. Further, in the fixed type constant velocity universal joint disclosed in Patent Document 4, the ball 130 that is in the most protruding phase (phase angle φ = 0 °) when the maximum operating angle is taken is disengaged from the track groove 114 of the outer ring 110, A structure in which the track groove 114 of the outer ring 110 is shortened within a range in which the ball 130 adjacent to the ball 130 cannot be removed from the track groove 114 of the outer ring 110 has been proposed. By adopting such a structure, interference with the shaft 150 is avoided and the angle of the joint is increased.

In the figure, the movement trajectory m of the point where the ball 130 moving in the axial direction in the track groove 114 of the outer ring 110 contacts the track groove 114 is indicated by a broken line. Further, the contact point A of the ball 130 that is out of the track groove 114 of the outer ring 110 is indicated by a cross in the figure.
JP 2001-153149 A JP 2001-304282 A JP 2001-349332 A Japanese Examined Patent Publication No. 6-68290

  By the way, in the fixed type constant velocity universal joint disclosed in the above-mentioned Patent Document 4, the contact point A between the ball 130 and the outer ring 110 that is in the most protruded phase at the maximum operating angle is removed from the track groove 114 of the outer ring 110. Further, a structure in which the track groove 114 of the outer ring 110 is shortened is adopted. In this case, it is an effective means for avoiding interference with the shaft 150 and realizing a high angle joint.

  However, once the contact point A between the ball 130 in the most projecting phase at the maximum operating angle and the track groove 114 of the outer ring 110 is removed from the track groove 114, the contact point A is again accommodated in the track groove 114 of the outer ring 110. Until then, the behavior of the ball 130 in the detached state becomes unstable, which may cause vibration and abnormal noise.

  At this maximum operating angle, there is a phase in which the load applied to the ball 130 for torque transmission is removed twice during one rotation of the joint. At that time, the ball 130 is unstable due to release from the load. The phenomenon that becomes the state has been confirmed. When such a phenomenon occurs, when the load of the ball 130 is released or a load is applied to the ball 130 again, a forcing force acts on the ball 130 and collides with the track groove 114 of the outer ring 110 or the track groove 124 of the inner ring 120. Doing so may cause vibration and abnormal noise.

  Therefore, the present invention has been proposed in view of the above-described problems, and the object of the present invention is to re-enter the track groove after the ball in the phase that protrudes most at the maximum operating angle is removed from the track groove of the outer ring. An object of the present invention is to provide a high-angle fixed type constant velocity universal joint capable of stabilizing the behavior of a ball or the like until it is accommodated.

  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 on the inner spherical surface at equal intervals in the circumferential direction toward the opening end along the axial direction, A plurality of track grooves that are paired with the track grooves of the outer joint member, and are formed 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, the outer spherical center and the inner spherical center of the cage being the joint center In the longitudinal section of the cage, the opening end side of the outer joint member is made thicker and the non-opening end side is made thinner, and the center of curvature of the track groove of the outer joint member is outside. At the center of the inner spherical surface of the joint member And the center of curvature of the track groove of the inner joint member is offset axially opposite to the outer spherical center of the inner joint member, and the groove end on the open end side of the track groove of the outer joint member faces the open end. In addition, the outer bottom of the track groove of the inner joint member has a tapered shape that is linearly enlarged toward the opposite end of the track groove, thereby offsetting the outer spherical surface of the cage. Satisfy at least one of the following conditions: the amount of the offset is larger than the offset amount of the spherical surface in the cage, or the offset amount of the track groove of the outer joint member is larger than the offset amount of the track groove of the inner joint member It is characterized by.

  That is, in the fixed type constant velocity universal joint of the present invention, the offset amount of the outer spherical surface of the cage is larger than the offset amount of the inner spherical surface of the cage, or the offset amount of the track groove of the outer joint member is set to the track groove of the inner joint member. The offset amount of the outer spherical surface of the cage is larger than the offset amount of the spherical surface of the cage, and the offset amount of the track groove of the outer joint member is larger than the offset amount of the track groove of the inner joint member. Larger forms are possible.

  In the present invention, the offset amount of the outer spherical surface of the cage is made larger than the offset amount of the spherical surface of the cage, or the offset amount of the track groove of the outer joint member is made larger than the offset amount of the track groove of the inner joint member. By shortening the track groove of the outer joint member by satisfying at least one of the conditions, the position of the ball that is in the most popping out phase even if the ball in the most popping out phase at the maximum operating angle deviates from the track groove The PCD clearance at can be reduced. Here, “PCD clearance” means the difference between the pitch circle diameter of the ball in contact with the track groove of the outer joint member and the pitch circle diameter of the ball in contact with the track groove of the inner joint member. To do.

  Thus, by reducing the PCD clearance, it is possible to reduce or eliminate the phase region from which the ball load is removed. As a result, the behavior of the ball can be stabilized until it is once removed from the track groove and then re-entered into the track groove, and the behavior of the ball can also be stabilized by reducing or eliminating the phase region through which the ball load is removed. it can.

  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, it is preferable that the taper angle is not less than half of the maximum operating angle because a 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.

  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 configuration, the cage offset amount f between the outer spherical center and the inner spherical center of the cage, and the distance PCR between 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 ball center. It is desirable that the ratio value f / 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 opening side of the outer joint member, the thickness of the cage on the opening side of the outer joint member is increased to improve the strength. It has the advantage that can be aimed at. Further, by increasing the thickness of the cage on the opening side of the outer joint member, when the operating angle is taken, the ball that is about to jump out from the opening end of the outer joint member can be restrained by the cage.

  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 distance PCR between 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 ball center is used.

  Therefore, the cage offset amount in the above-described configuration is the cage offset amount f and the distance PCR between 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 ball center when the operating angle is 0 °. It is desirable that the ratio f / PCR is greater than 0 and 0.12 or less.

  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, when the cage offset amount f is 0, the track offset amount is also 0, so the offset becomes 0, the ball (cage) position is not determined when the wedge angle = 0, and the operability is significantly deteriorated. In range, the purpose cannot be achieved. 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.

  The present invention can be applied to a fixed type constant velocity universal joint having six or eight balls. However, when applied to a fixed type constant velocity universal joint having eight balls, the fixed type constant velocity universal joint is applicable. This is effective in that the universal joint can be made compact.

  In the present invention, the offset amount of the outer spherical surface of the cage is made larger than the offset amount of the spherical surface of the cage, or the offset amount of the track groove of the outer joint member is made larger than the offset amount of the track groove of the inner joint member. By shortening the track groove of the outer joint member by satisfying at least one of the conditions, the position of the ball that is in the most popping out phase even if the ball in the most popping out phase at the maximum operating angle deviates from the track groove The PCD clearance at can be reduced.

  Thus, by reducing the PCD clearance, it is possible to reduce or eliminate the phase region from which the ball load is removed. As a result, the behavior of the ball can be stabilized until it is once removed from the track groove and then re-entered into the track groove, and the behavior of the ball can also be stabilized by reducing or eliminating the phase region through which the ball load is removed. It is possible to suppress the occurrence of vibration and abnormal noise.

  As a result, it is possible to easily increase the operating angle, and in response to the desire to lengthen the wheel base from the viewpoint of expanding the riding space of automobiles in recent years, the steering angle of the front wheels has been reduced so as not to increase the vehicle turning radius. Increase can be easily achieved.

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

  The fixed type constant velocity universal joint shown in FIG. 1 includes an outer ring 10, an inner ring 20, a ball 30, and a cage 40 as main components. Two shafts to be connected by this fixed type constant velocity universal joint, for example, a driven rotary shaft (not shown) is connected to the outer ring 10, and a drive rotary shaft (not shown) is connected to each other. Torque is transmitted at a constant speed even in a state where 6 shows a state in which the rotation axis X of the outer ring 10 and the rotation axis Y of the inner ring 20 (the central axis of the shaft 50 connected to the inner ring 20) take the maximum operating angle θ, and FIG. Indicates a state of 0 °.

  The outer ring 10 serving as an outer joint member includes a mouth portion 16 and a stem portion (not shown), and is coupled to the driven-side rotating shaft at the stem portion so that torque can be transmitted. The mouse portion 16 has a bowl shape opened at one end, and a plurality of track grooves 14 extending in the axial direction are formed on the inner spherical surface 12 at equal intervals in the circumferential direction. The track groove 14 extends to the open end 18 of the mouse portion 16.

  The inner ring 20 as an inner joint member has a plurality of track grooves 24 extending in the axial direction formed on the outer spherical surface 22 at equal intervals in the circumferential direction. The track groove 24 is cut in the axial direction of the inner ring 20. The inner ring 20 has a spline hole 26 for coupling with a drive-side rotating shaft so as to transmit torque.

  The track groove 14 of the outer ring 10 and the track groove 24 of the inner ring 20 make a pair, and a ball 30 as a torque transmitting element can roll on each ball track constituted by the pair of track grooves 14, 24. It is incorporated. The ball 30 is interposed between the track groove 14 of the outer ring 10 and the track groove 24 of the inner ring 20 to transmit torque.

  Each ball 30 is accommodated in a pocket 46 disposed in the circumferential direction of the cage 40. The number of balls 30, in other words, the number of track grooves 14, 24 is arbitrary, but 6 or 8 for example. In order to realize a compact constant velocity universal joint, eight balls 30 are preferable as in this embodiment.

The cage 40 is slidably interposed between the outer ring 10 and the inner ring 20, is in contact with the inner spherical surface 12 of the outer ring 10 at the outer spherical surface 42, and is in contact with the outer spherical surface 22 of the inner ring 20 at the inner spherical surface 44. The center of curvature of the inner spherical surface 12 of the outer ring 10 and the center of curvature of the outer spherical surface 42 of the cage 40 coincide with each other, and are denoted by reference numeral O ₄ in FIG. Similarly, coincide with the center of curvature of the inner spherical surface 44 of the center of curvature and the cage 40 of the outer spherical surface 22 of the inner ring 20, it is indicated by reference numeral O ₃ in FIG. In the drawing, the clearance between the inner spherical surface 12 of the outer ring 10 and the outer spherical surface 42 of the cage 40 and between the outer spherical surface 22 of the inner ring 20 and the inner spherical surface 44 of the cage 40 are exaggerated.

  The track groove 14 of the outer ring 10 includes an arc portion 14a and a straight portion 14b. The arc portion 14a is located on the back side of the mouse portion 16, that is, on the side opposite to the opening, and the straight portion 14b is located on the opening end side. The track groove 14 has a taper shape with a taper angle α that linearly increases the diameter of the groove bottom on the opening end side toward the opening end 18.

  The track groove 24 of the inner ring 20 includes an arc portion 24a and a straight portion 24b. The arc portion 24a is located on the opening end side of the outer ring 10, and the straight portion 24b is located on the counter-opening end side. The track groove 24 has a tapered shape with a taper angle α that linearly expands the groove bottom on the back side of the outer ring 10, that is, on the side opposite to the opening side toward the side opposite to the opening side.

Since this joint has a structure that can take a large operating angle θ, as shown in FIG. 2, the center of curvature O ₁ of the track groove 14 of the outer ring 10 is tracked with respect to the center O ₄ of the inner spherical surface 12. The curvature center O ₂ of the groove 24 is offset in the axial direction opposite to the center O ₃ of the outer spherical surface 22 (track offset). Similarly, the center of curvature O ₃ center of curvature O ₄ and the inner spherical surface 44 of the outer spherical surface 42 of the cage 40, thereby axially offset opposite direction to the joint center O (cage offset). This cage offset amount is set larger than the track offset amount.

  As shown in FIG. 6, when the rotation axis X of the outer ring 10 and the rotation axis Y of the inner ring 20 take a certain operating angle θ other than 0 °, a bisector of the angle θ formed by both the rotation axes X and Y is obtained. If all the balls 30 are in the vertical plane, that is, the joint center plane P, the distances from the ball center to the two rotation axes X and Y are equal to each other. Transmission takes place. 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.

  The ball track constituted by the track groove 14 of the outer ring 10 and the track groove 24 of the inner ring 20 that form a pair is provided with a track offset so that the radial direction from the back side of the mouth portion 16 of the outer ring 10 toward the opening end side is provided. It has a wedge shape in which the interval gradually increases.

  Since the cage 40 is provided with the cage offset as described above, the cage 40 has a shape that is thick toward the opening end side of the outer ring 10 and thin toward the opposite opening end side. That is, the thick part 41 is arranged on the opening end side of the outer ring 10, and the thin part 43 is arranged on the opposite opening end side. The outer spherical surface side of the thick portion 41 is extended in the axial direction, and the inner spherical surface side of the thick portion 41 is tapered toward the outer spherical surface.

  Thus, by extending the outer spherical surface side of the thick portion 41 of the cage 40 in the axial direction, the outer spherical surface 42 of the cage 40 and the outer ring 10 can be obtained even in a high angle region when the joint takes the maximum operating angle. A contact area with the inner spherical surface 12 can be ensured. As a result, even when the ball 30 pushes the cage 40 toward the opening end side and the outer spherical surface 42 of the thick portion 41 of the cage 40 and the inner spherical surface 12 of the outer ring 10 rub against each other strongly, the durability is reduced due to heat generation and the transmission torque is reduced. Loss can be minimized. Moreover, since the rigidity of the cage 40 can be ensured to the maximum, the strength of the cage itself is also improved.

  Further, the shaft 50 attached to the inner ring 20 with the joint having the maximum operating angle is formed by a taper shape in which the inner spherical surface side of the thick portion 41 of the cage 40 is enlarged toward the outer spherical surface side. It is possible to prevent interference with the thick portion 41 of the cage 40 (see FIG. 6).

  In the constant velocity universal joint of this embodiment, as shown in FIG. 6, the contact point B of the ball 30 in the phase that protrudes most at the maximum operating angle (phase angle φ = 0 °) is separated from the track groove 14 of the outer ring 10. The track groove 14 is shortened. Thus, by shortening the track groove 14 of the outer ring 10 in the axial direction, it becomes easy to avoid the interference with the shaft 50 and realize a high angle of the joint. In the drawing, the movement locus n of the point where the ball 30 moving in the axial direction in the track groove 14 of the outer ring 10 contacts the track groove 14 is indicated by a dotted line. Further, a contact point B of the ball 30 that has come off the track groove 14 of the outer ring 10 is indicated by a cross in the figure.

  As described above, by shortening the track groove 14 of the outer ring 10, the contact point B of the ball 30 at the most popping out phase (phase angle φ = 0 °) at the maximum operating angle is deviated from the track groove 14. The offset amount of the outer spherical surface 42 of the cage 40 is made larger than the offset amount of the inner spherical surface 44 of the cage 40, or the offset amount of the track groove 14 of the outer ring 10 is made larger than the offset amount of the track groove 24 of the inner ring 20. It is set so as to satisfy at least one of the points.

The relationship between the cage offset amount and the track offset amount described above can be realized by a constant velocity universal joint having the form shown in FIGS. 3 to 5, only the cage offset amounts f ₁ and f ₂ and the track offset amounts F ₁ and F ₂ are shown, and the components of the joint are not shown (see FIG. 2).

In the constant velocity universal joint of the form shown in FIG. 3, the offset amount F ₁ of the track groove 14 of the outer ring 10 and the offset amount F ₂ of the track groove 24 of the inner ring 20 are made the same (F ₁ = F ₂ ). The offset amount f ₁ of the spherical surface 42 is made larger than the offset amount f ₂ of the inner spherical surface 44 of the cage 40 (f ₁ > f ₂ ).

In the constant velocity universal joint shown in FIG. 4, the offset amount f ₁ of the outer spherical surface 42 of the cage 40 and the offset amount f ₂ of the inner spherical surface 44 of the cage 40 are the same (f ₁ = f ₂ ), and the track of the outer ring 10 is made. The offset amount F ₁ of the groove 14 is made larger than the offset amount F ₂ of the track groove 24 of the inner ring 20 (F ₁ > F ₂ ).

In the constant velocity universal joint of the form shown in FIG. 5, the offset amount f ₁ of the outer spherical surface 42 of the cage 40 is made larger than the offset amount f ₂ of the inner spherical surface 44 of the cage 40 (f ₁ > f ₂ ), and the outer ring 10 The offset amount F ₁ of the track groove 14 is made larger than the offset amount F ₂ of the track groove 24 of the inner ring 20 (F ₁ > F ₂ ).

As described above, the offset amount f ₁ of the outer spherical surface 42 of the cage 40 is made larger than the offset amount f ₂ of the inner spherical surface 44 of the cage 40 or the offset amount F ₁ of the track groove 14 of the outer ring 10 is set to the inner ring 20. at least that one condition is satisfied of the point to be larger than the offset amount F ₂ of the track groove 24, by shortening the track grooves 14 of the outer ring 10, the maximum operating angle as shown in FIGS. 6 and 7 Even when the ball 30 that is in the most popping out phase sometimes deviates from the track groove 14, the PCD clearance at the position of the ball 30 in the most popping out phase can be reduced.

  That is, the PCD clearance is the pitch circle diameter (outer ring PCD) of the ball 30 in contact with the track groove 14 of the outer ring 10 and the pitch circle diameter (inner ring PCD) of the ball 30 in contact with the track groove 24 of the inner ring 20. Therefore, reducing the PCD clearance means reducing the difference between the outer ring PCD and the inner ring PCD. 6 shows a case where (outer ring PCD) − (inner ring PCD) = 0, that is, the PCD clearance becomes 0, and FIG. 7 shows (outer ring PCD) − (inner ring PCD) <0, that is, the PCD clearance is negative. Shows the case. Note that setting the PCD clearance to 0 or negative means closing the PCD clearance.

  Thus, by reducing the PCD clearance, it is possible to reduce or eliminate the phase region from which the load of the ball 30 is removed. As a result, the behavior of the ball 30 can be stabilized until the ball 30 is once removed from the track groove 14 of the outer ring 10 and is again set in the track groove 14, and the ball 30 can be reduced or eliminated by reducing or eliminating the phase region from which the load of the ball 30 is removed. Can be stabilized, and the occurrence of vibration and noise can be suppressed.

When the outer ring 10 and the inner ring 20 take the maximum operating angle θ, the cage offset amount f is set so that the ball 30 can be restrained by the pocket 46 of the cage 40 in order to prevent the ball 30 from jumping out from the opening end 18 of the mouth portion 16 of the outer ring 10. Is set larger than the conventional one. That is, the cage offset amount is f, the radius of the center locus of the ball 30, that is, the center of curvature O ₁ of the track groove 14 of the outer ring 10 or the center of curvature O ₂ of the track groove 24 of the inner ring 20 and the ball 30 when the operating angle is 0 °. Assuming that the length of the line connecting the center O ₅ is PCR, f / PCR is set to be greater than 0 and 0.12 or less.

  Thus, if both the track grooves 14 and 24 of the outer ring 10 and the inner ring 20 are tapered, the maximum operating angle can be increased and the contact length with the ball 30 in the track groove 14 of the outer ring 10 can be secured. Therefore, stable torque transmission can be ensured between the outer ring 10 and the inner ring 20. Further, since the track load and the pocket load of the phase (phase angle φ = 0 °) (see FIG. 6) in which the ball 30 is most likely to jump out when the operating angle is taken can be reduced, the outer ring 10 and the inner ring 20 can be reduced. This is advantageous for operation in the high angle range. Here, the track load means a load received by the track grooves 14 and 24 from the ball 30 in contact.

  Further, the outer spherical surface 42 of the cage 40 is contact-guided to the inner spherical surface 12 of the outer ring 10, and the inner spherical surface 44 of the cage 40 is contact-guided to the outer spherical surface 22 of the inner ring 20, so that the cage 40 and the outer ring 10 or the inner ring 20 are 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.

  By making both the track grooves 14 and 24 of the outer ring 10 and the inner ring 20 into a tapered shape, the influence and tendency of the internal force including the track load, pocket load and spherical force described above are verified, and a finite element method (FEM) analysis is performed. By carrying out, the range of the taper angle α (see FIGS. 1 and 2) of the track grooves 14 and 24 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 14 and 24 is shown in Table 1. In Table 1, the phase at which the ball 30 is most likely to jump out (phase angle φ = 0 °) and the phase of the ball 30 at which the internal force is maximum, that is, the phase at which the ball 30 is deepest (phase angle φ = Around 180 °) (see FIG. 8). The fluctuation range of the spherical force means a difference between the maximum value and the minimum value of the spherical force.

  As apparent from Table 1, when the taper angle α is increased, the maximum value of the pocket load is increased, but the wall thickness of the outer ring 10 is increased at the phase where the ball 30 enters the innermost part (phase angle φ = 180 °), Further, since the strength can be ensured by increasing the cage offset amount and increasing the thickness of the cage 40, 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 °) in which the ball 30 is most likely to jump out, which is advantageous in terms of strength. Since it is the opening end 18 and its wall thickness becomes small, the tendency was confirmed by converting the stress value generated in the track groove 14 into 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. When the track offset is provided, the arc portion 14a of the track groove 14 of the outer ring 10 becomes shallower toward the inner side, so that the ball 30 positioned at the innermost portion of the track groove 14 rides up when the operating angle is taken. May occur.

Accordingly, the center of curvature O ₁ of the track groove 14 of the outer ring 10 is made to coincide with the center of curvature O ₄ of the inner spherical surface 12, and the center of curvature O ₂ of the track groove 24 of the inner ring 20 is made to be the center of curvature O _{3 of the} outer spherical surface 22. By making the track offset amount F equal to 0, the arc portion 14a of the track groove 14 of the outer ring 10 has a uniform depth without becoming shallow toward the back side. It is possible to suppress the riding of the ball 30 located at the innermost part of the track groove 14.

  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 30 is most likely to jump out are zero. become. On the other hand, when 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 30 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. 10, the track load and pocket load at the phase (0 ° phase) at which the ball 30 is most likely to jump out are zero. Become. Here, FIG. 10 is drawn based on data calculated by internal force analysis, and 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) where the ball 30 is most likely to jump out minimized.
Track offset: None Cage offset amount f: 0 <f / PCR ≦ 0.12
Taper angle α: 1 ° ≦ α ≦ 12 °

  Further, in this embodiment, the load at the phase (0 ° phase) where the ball 30 is most likely to jump out is reduced, while the peak load is larger than that of the conventional constant velocity universal joint, so that the strength is ensured. Therefore, it is preferable to arrange the thick portion 41 of the cage 40 toward the opening end side of the outer ring 10.

  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, the ball 30 at the maximum operating angle is most likely to jump out. When the track load and the pocket load in the phase (0 ° phase) 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.

  The present invention is not limited to the above-described embodiments, and can of course be implemented in various forms without departing from the gist of the present invention. It includes the equivalent meanings recited in the claims and the equivalents recited in the claims, and all modifications within the scope.

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 explanatory drawing which shows the relationship between a cage offset amount and a track offset amount, and shows the case where the offset amount of a cage outer spherical surface is made larger than the offset amount of a cage inner spherical surface. In the constant velocity universal joint of FIG. 1, it is explanatory drawing which shows the relationship between a cage offset amount and a track offset amount, and shows the case where the offset amount of an outer ring track groove is made larger than the offset amount of an inner ring track groove. In the constant velocity universal joint shown in FIG. 1, the relationship between the cage offset amount and the track offset amount is shown. The offset amount of the outer spherical surface of the cage is made larger than the offset amount of the inner spherical surface of the cage, and the offset amount of the outer ring track groove is It is explanatory drawing which shows the case where it makes larger than offset amount. In the constant velocity universal joint of FIG. 1 (PCD clearance = 0), it is a cross-sectional view showing a state in which the inner ring takes a maximum operating angle with respect to the outer ring. FIG. 2 is a cross-sectional view showing a state in which the inner ring takes a maximum operating angle with respect to the outer ring in the constant velocity universal joint of FIG. 1 (PCD clearance <0). 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 the basic torque load at the time of a maximum operating angle. 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. 12, it is sectional drawing which shows the state which the inner ring took the maximum operating angle with respect to the outer ring.

Explanation of symbols

10 Outer joint member (outer ring)
12 Inner spherical surface of outer joint member (outer ring) 14 Track groove of outer joint member (outer ring) 18 Open end 20 Inner joint member (inner ring)
22 Outer spherical surface of inner joint member (inner ring) 24 Track groove of inner joint member (inner ring) 30 Ball 40 Cage 42 Outer spherical surface of cage 44 Inner spherical surface of cage f ₁ , f ₂ Cage offset amount F ₁ , F ₂ 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

Claims (6)

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 the ball interposed between the outer spherical surface of the inner joint member,
The outer spherical center and inner spherical center of the cage are offset in the axial direction opposite to the joint center, and in the longitudinal section of the cage, the opening end side of the outer joint member is thickened and the opposite opening end side is thin. West,
The center of curvature of the track groove of the outer joint member is offset to the inner spherical center of the outer joint member, and the center of curvature of the track groove of the inner joint member is offset axially opposite to the outer spherical center of the inner joint member. And the opening end side groove bottom of the track groove of the outer joint member is tapered to linearly expand toward the opening end, and the non-opening end side groove bottom of the track groove of the inner joint member is The taper is linearly expanded toward the opposite end of the opening,
The offset amount of the outer spherical surface of the cage is made larger than the offset amount of the spherical surface of the cage, or the offset amount of the track groove of the outer joint member is made larger than the offset amount of the track groove of the inner joint member. A fixed type constant velocity universal joint characterized by satisfying one of the conditions.   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 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 fixed type constant velocity universal joint according to any one of claims 1 to 3, 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 inner spherical center of the cage, and the distance PCR between 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 ball center when the operating angle is 0 °. The fixed type constant velocity universal joint according to any one of claims 1 to 4, wherein a ratio value f / PCR with respect to is greater than 0 and 0.12 or less.   The fixed constant velocity universal joint according to claim 1, wherein the number of balls is eight.

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