JP4896662B2 - 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.

  In general, 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-described 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).

10 shows a state in which the joint has a maximum operating angle θ ₀ , that is, the maximum operating angle is the rotational axis X of the outer ring 110 and the rotational axis Y of the inner ring 120 (the central axis of the shaft 150 connected to the inner ring 120). A state where θ ₀ is taken is shown. In the figure, the movement locus m _{01 of the} point where the ball 130 moving in the axial direction on the track groove 114 of the outer ring 110 contacts the track groove 114, and the ball 130 moving in the axial direction on the track groove 124 of the inner ring 120 is the track groove. The movement trajectory m ₀₂ of the point in contact with 124 is indicated by a broken line. L ₀₁ represents the axial dimension of the track groove 114 of the outer ring 110 in the movement locus m ₀₁ of the ball 130, and L ₀₂ represents the axial dimension of the track groove 124 of the inner ring 120 in the movement locus m ₀₂ of the ball 130.
JP 2001-153149 A JP 2001-304282 A JP 2001-349332 A

  By the way, in the fixed type constant velocity universal joint described above, the opening side groove bottom of the track groove 114 of the outer ring 110 is formed into a taper shape linearly expanding toward the opening side of the outer ring 110, and the track groove of the inner ring 120 is formed. The working angle is increased by making the rear groove bottom of 124 a tapered shape that linearly increases in diameter toward the inner side of the inner ring 120.

  On the other hand, in this fixed type constant velocity universal joint, it is necessary to increase the outer diameter of the outer ring 110 in order to further increase the operating angle. However, when the outer diameter of the outer ring 110 is increased, it is difficult to make the constant velocity universal joint compact, and space is limited when the constant velocity universal joint is mounted on an automobile or the like. In addition, the weight of the constant velocity universal joint is increased and the cost of the product is increased.

  Therefore, the present invention has been proposed in view of the above-mentioned problems, and the object of the present invention is to reduce the weight and the cost in a high-angle type fixed constant velocity universal joint having a tapered track groove. While aiming, it is to realize further higher angle.

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. And the taper shape of the inner joint member's track groove on the non-opening end side of the groove is linearly enlarged toward the anti-opening end side, and is outside at the maximum operating angle. Remove the contact point between the track grooves and the track grooves of the inner joint member of the outer joint member of the ball in the most popping phase from the track grooves in the joint members from each of the track grooves, and an outer joint member of three or more balls simultaneously to the extent that the point of contact with the track groove of the track grooves and the inner joint member from coming off each of the track grooves, Jikukata the track grooves of the track groove and the inner joint member of the outer joint member Characterized by being shortened.

In the present invention, the track groove of the outer joint member is axially arranged so that the contact point with the track groove of the outer joint member of the ball in the phase that protrudes most from the track groove of the outer joint member at the maximum operating angle is removed from the track groove. When the joint takes an operating angle, a space can be created between the open end of the outer joint member and the shaft connected to the inner joint member. Further, it is easy to realize a higher angle. In addition, by shortening the track groove of the inner joint member in the axial direction so that the contact point with the track groove of the inner joint member of the ball in the most protruding phase is removed from the track groove, the inner joint member can be made compact and Easy integration into the cage.

If the contact point between the most popping ball and the track groove of the ball located on both sides thereof is simultaneously removed from the track groove, a total of three ball contact points will be removed from the track groove. This will cause functional problems. Therefore, if shortening the track grooves of the track groove and the inner joint member of the outer joint member in the axial direction, the contact point between the three or more track grooves and the track grooves of the inner joint member of the outer joint member of the ball at the same time each It is necessary to make the range that does not deviate from the track groove.

  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 contact point between the track groove of the outer joint member of the ball and the track groove of the inner joint member which is in the phase most protruding from the track groove of the outer joint member at the maximum operating angle is removed from each track groove, and at the same time As long as the contact point between the track groove of the outer joint member and the track groove of the inner joint member of three or more balls does not deviate from each track groove, the track groove of the outer joint member and the track groove of the inner joint member are axially When the joint takes an operating angle, it is possible to create a space for further operating angle between the open end of the outer joint member and the shaft connected to the inner joint member. high angle of is facilitated realization, incorporation into compact and cage of the inner joint member is facilitated, compact lightweight of the constant velocity universal joint And cost reduction can be achieved.

  As a result, since it is possible to easily increase the operating angle, the steering angle of the front wheels is set so that the vehicle turning radius does not increase in response to the demand for a longer wheel base from the viewpoint of increasing the vehicle space in recent years. Can be easily increased.

  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 3 and 4 show 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 ₁ . Indicates a state in which the operating angle is 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.

In this joint, in order to obtain a structure that can have a large operating angle θ ₁ , the center of curvature O ₁ of the track groove 14 of the outer ring 10 is set to be equal to the center O ₄ of the inner spherical surface 12 as shown in FIG. The center of curvature O ₂ of the track 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 f is set larger than the track offset amount F.

As shown in FIGS. 3 and 4, 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 ₁ other than 0 °, the angle θ ₁ formed by both the rotation axes X and Y If all the balls 30 are in the plane perpendicular to the bisector, 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. Rotational motion is transmitted at angular velocity. 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 and the outer ring of the cage 40 can be obtained even in the high angle region when the joint takes the maximum operating angle θ _1. A contact area with 10 inner spherical surfaces 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 attached to the inner ring 20 with the joint having the maximum operating angle θ ₁ 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. 50 can be prevented from interfering with the thick portion 41 of the cage 40 (see FIGS. 3 and 4).

FIG. 3 shows a reference example of the present invention. In the figure, the movement trajectory m _{11 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 and the ball 30 moving in the axial direction in the track groove 24 of the inner ring 20 are in the track groove. The movement trajectory m ₀₂ of the point in contact with 24 is indicated by a broken line. L ₁₁ indicates the axial dimension of the track groove 14 of the outer ring 10 in the movement locus m ₁₁ of the ball 30, and L ₀₂ indicates the axial dimension of the track groove 24 of the inner ring 20 in the movement locus m ₀₂ of the ball 30.

In the constant velocity universal joint of this reference example , as shown in FIG. 3, the contact point A (marked with x in the figure) of the ball 30 in the phase that protrudes most at the maximum operating angle (phase angle φ = 0 °) is the outer ring 10. The track groove 14 is shortened so as to be separated from the track groove 14. That is, the axial dimension L ₁₁ of the track groove 14 of the outer ring 10 in the movement locus m ₁₁ of the ball 30 is the same as that of the conventional constant velocity universal joint (see FIG. 10), that is, the outer ring 110 in the movement locus m ₀₁ of the ball 130. This is shorter than the axial dimension L ₀₁ of the track groove 114 (L ₀₁ > L ₁₁ ).

Thus, by shortening the track groove 14 of the outer ring 10 in the axial direction, when the joint takes an operating angle, a space is created between the opening end 18 of the outer ring 10 and the shaft 50 so that the operating angle can be further increased. Therefore, it is easy to avoid the interference with the shaft 50 and realize a high angle of the joint, and the maximum operating angle can be made larger than that of the conventional constant velocity universal joint (see FIG. 10) ( θ ₀ <θ ₁ ).

In the reference example shown in FIG. 3, the axial dimension L ₀₂ of the track groove 24 of the inner ring 20 in the movement trajectory m ₀₂ of the ball 30 is the same as that of the conventional constant velocity universal joint (see FIG. 10). The contact point B of the ball 30 which is the same as the axial dimension L ₀₂ of the track groove 124 of the inner ring 120 in the movement trajectory m ₀₂ of the ball 130 and is in the most popping out phase (phase angle φ = 0 °) at the maximum operating angle. It does not come off from the track groove 24 of the inner ring 20.

FIG. 4 illustrates one embodiment of the present invention. The same parts as those in the above-described reference example of FIG. In the constant velocity universal joint of this embodiment, as shown in FIG. 4, the contact point B of the ball 30 in the phase that protrudes most at the maximum operating angle (phase angle φ = 0 °) is disengaged from the track groove 24 of the inner ring 20. The track groove 24 is shortened. That is, the axial dimension L ₁₂ of the track groove 24 of the inner ring 20 in the movement locus m ₁₂ of the ball 30 is the same as that of the conventional constant velocity universal joint (see FIG. 10), that is, the inner ring 120 in the movement locus m ₀₂ of the ball 130. This is shorter than the axial dimension L ₀₂ of the track groove 124 (L ₀₂ > L ₁₂ ).

  As in this embodiment, the track groove 24 is shortened so that the contact point B of the ball 30 is disengaged from the track groove 24 of the inner ring 20, so that the inner ring 20 can be made compact and incorporated in the cage 40. It is effective in.

  It should be noted that when the contact points A and B of the ball 30 (phase angle φ = 0 °) that is in the most protruding phase and the ball 30 located on both sides thereof are separated from the track groove 14 of the outer ring 10 or the track groove 24 of the inner ring 20, The contact points A and B of the three balls 30 are disengaged from the track groove 14 of the outer ring 10 or the track groove 24 of the inner ring 20, which hinders the function of the constant velocity universal joint. Therefore, when the track groove 14 of the outer ring 10 or the track groove 24 of the inner ring 20 is shortened in the axial direction, the contact points A and B of three or more balls 30 simultaneously become the track groove 14 of the outer ring 10 or the track groove 24 of the inner ring 20. It is necessary to make the range not deviated from.

  For the ball 30 from which the contact points A and B with the track grooves 14 and 24 come off, the internal characteristics of this constant velocity universal joint, that is, the track groove 14 of the outer ring 10 or the track groove 24 of the inner ring 20 are tapered. Accordingly, the load applied is set so as to be very small. Therefore, the contact points A and B of the ball 30 are disengaged from the track groove 14 of the outer ring 10 or the track groove 24 of the inner ring 20. The possibility of occurring is very small.

  In this constant velocity universal joint, since the track groove 14 of the outer ring 10 or the track groove 24 of the inner ring 20 is tapered, the amount of movement of the ball 30 in the radial direction increases. In order to secure a contact point with 46, it is necessary to set a large thickness on the outer ring opening end side of the cage 40. In the constant velocity universal joint of this embodiment, as will be described later, by setting the cage offset amount f larger than the conventional one, the thickness of the outer ring opening end side of the cage 40 is increased to increase the ball 30 and the pocket 46 of the cage 40. It is easy to secure the contact point with the. Although the contact point between the ball 30 and the pocket 46 of the cage 40 may be disengaged on the side opposite to the outer ring opening side of the cage 40, there is no problem because the applied load is very small.

In order to prevent the ball 30 from jumping out from the open end 18 of the mouth portion 16 of the outer ring 10 when the outer ring 10 and the inner ring 20 have the maximum operating angle θ ₁ , the cage offset amount can be restrained by the pocket 46 of the cage 40. f 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 pocket load of the phase (phase angle φ = 0 °) (see FIGS. 3 and 4) in which the ball 30 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 20 in a high angle region. 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 = Near 180 °) (see FIG. 5). 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. 7, 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. 7 is plotted 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 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 reference example of this invention, it is sectional drawing which shows the state which the inner ring took the largest operating angle with respect to the outer ring. In one embodiment of the present invention, it is a cross-sectional view showing a state where the inner ring took 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. 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. FIG. 10 is a cross-sectional view showing a state in which the inner ring has a maximum operating angle with respect to the outer ring in the constant velocity universal joint of FIG. 9.

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 A, B Contact point f Cage offset amount F Track offset amount O ₁ outside Center of curvature of track groove of 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 contact point of the ball in the phase that protrudes most from the track groove of the outer joint member at the maximum operating angle is removed from the track groove of the outer joint member and the track groove of the inner joint member from each track groove, and at least three at the same time. The track groove of the outer joint member and the track groove of the inner joint member are shortened in the axial direction so that the contact points of the balls of the outer joint member and the track groove of the inner joint member do not deviate from the respective track grooves. A fixed type constant velocity universal joint.   2. A tapered shape in which an opening-side end portion of the outer spherical surface of the cage extends in the axial direction and an opening-side end portion of the inner spherical surface of the cage expands toward the opening-side end portion of the outer spherical surface. Fixed 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 type constant velocity universal joint according to any one of claims 1 to 5, wherein the number of balls is six or eight.

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