JP4041641B2 - Fixed type constant velocity universal joint - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
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.
[0002]
[Prior art]
In recent years, the wheelbase may be lengthened from the viewpoint of improving the collision safety of automobiles, but in order to prevent the turning radius of the vehicle from increasing accordingly, the steering angle of the front wheels is increased by increasing the angle of the fixed type constant velocity universal joint. There is a need for an increase. The present situation is that this need for higher angle is met by a fixed constant velocity universal joint of UF (undercut free) type in which the shape of the track groove on the opening side of the outer joint member is parallel to the axial direction. .
[0003]
As shown in FIGS. 7 and 8 , the UF type fixed type constant velocity universal joint is formed with a plurality of track grooves 2 on the inner spherical surface 1 at equal intervals in the circumferential direction toward the opening end 3 along the axial direction. An outer joint member 5 having a mouse portion 4 and an inner joint member 8 in which a plurality of track grooves 7 paired with the track grooves 2 of the outer joint member 5 are formed on the outer spherical surface 6 along the axial direction at equal intervals in the circumferential direction. A plurality of balls 9 interposed between the track grooves 2 and 7 of the outer joint member 5 and the inner joint member 8 to transmit torque, the inner spherical surface 1 of the outer joint member 5 and the outer spherical surface 6 of the inner joint member 8. And a cage 10 for holding each ball 9 interposed therebetween. The plurality of balls 9 are accommodated in pockets 13 formed in the cage 10 and arranged at equal intervals in the circumferential direction.
[0004]
Here, FIG. 7 shows a state where the operating angle θ is 0 °, and FIG. 8 shows a state where the operating angle θ is the maximum angle (50 °). Although not shown, either the outer joint member 5 or the inner joint member 8 has a drive side rotation shaft, and the other has a driven side rotation shaft. The operating angle θ means an angle formed by the rotation axis X of the outer joint member 5 and the rotation axis Y of the inner joint member 8. In addition, when the rotation axis X of the outer joint member 5 and the rotation axis Y of the inner joint member 8 take a certain operating angle θ other than 0 °, they are perpendicular to the bisector of the angle θ formed by both the rotation axes X and Y. This plane is called the joint plane P. If all the balls 9 are on the joint plane P when the operating angle θ is taken, the distances from the ball center to the two rotation axes X and Y are equal to each other. Rotational motion is transmitted. An intersection of the joint 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.
[0005]
In the UF type fixed type constant velocity universal joint, both the track grooves 2 and 7 of the outer joint member 5 and the inner joint member 8 have no undercut and have a structure capable of taking a large operating angle. FIG. 9 shows an enlarged cross section (hatching is omitted) of FIG. 7 in order to explain the shapes of the track grooves 2 and 7 and the cage offset amount of the outer joint member 5 and the inner joint member 8.
[0006]
Each track groove 2 of the outer joint member 5 is formed with a predetermined depth from the inner spherical surface 1 of the outer joint member 5, and the depth gradually changes in the axial direction. The track groove 2 is in the back side of the mouth portion 4, and the circular arc bottom 2a having a curvature center O ₁ on the rotation axis X of the outer joint member 5, line segment track grooves extending from the center of curvature O ₁ in the radial direction 2 has a straight bottom 2b parallel to the rotation axis X on the opening side of the mouse portion 4 with a portion m intersecting with the bottom of 2 as a boundary. Each track groove 7 of the inner joint member 8 is formed at a predetermined depth from the outer spherical surface 6 of the inner joint member 8, but the depth gradually changes in the axial direction. The track groove 7 has an arc bottom 7 a having a center of curvature O ₂ on the rotation axis Y of the inner joint member 8 on the opening side of the mouth portion 4, and a line segment extending in the radial direction from the center of curvature O _2. 7 has a straight bottom 7 b parallel to the rotation axis Y on the back side of the mouse portion 4 with a portion n intersecting with the bottom of 7 as a boundary.
[0007]
The center of curvature of the outer spherical surface 6 of the inner joint member 8 and the center of curvature of the inner spherical surface 1 of the outer joint member 5 coincide with the centers of curvature O ₃ ′ and O ₄ ′ of the inner and outer spherical surfaces 11 and 12 of the cage 10, respectively. The centers of curvature O ₃ ′ and O ₄ ′ of the inner and outer spherical surfaces 11 and 12 of the cage 10 are offset from the joint center O in the axial direction by an equal distance f ′. Similarly, the center of curvature O ₁ of the track grooves 2 of the outer joint member 5, and the center of curvature O ₂ of the track grooves 7 of the inner joint member 8, the offset in the opposite direction only in the axial direction equidistantly f 'from joint center O is doing. Therefore, the pair of track grooves 2 and 7 form a wedge-shaped track whose interval gradually changes from one to the other in the axial direction. Each ball 9 is incorporated between a pair of track grooves 2 and 7 so as to be able to roll. When the outer joint member 5 and the inner joint member 8 transmit torque with the operating angle θ taken, It receives the action of an axial force that tries to move it toward the wider interval.
[0008]
[Problems to be solved by the invention]
In recent years, there is a need to further increase the angle by reducing the minimum turning radius of automobiles (especially mini cars and small cars) and liberating the geometry design of the undercarriage of automobiles, but with conventional UF type fixed constant velocity universal joints, The operating angle θmax = 50 ° is the limit, and in order to achieve a higher angle, it is necessary to increase the outer diameter of the mouth portion 4 of the outer joint member 5. For this reason, the current situation is that it must be designed to be light and compact.
[0009]
Therefore, the present invention has been proposed in view of the above-mentioned problems, and the object of the present invention is a fixed mold that can easily realize a high operating angle without increasing the outer diameter of the outer joint member. It is to provide a quick universal joint.
[0010]
[Means for Solving the Problems]
As technical means for achieving the above object, the present invention provides an outer joint member in which a plurality of track grooves are formed on the inner spherical surface at equal intervals in the circumferential direction toward the opening end along the axial direction. Torque by interposing between the track grooves of the outer joint member and the inner joint member, the inner joint member having a plurality of track grooves paired with the track grooves of the outer joint member formed along the axial direction at equal intervals in the circumferential direction In a fixed type constant velocity universal joint comprising a plurality of balls for transmitting a ball and a cage for holding the ball interposed between the inner spherical surface of the outer joint member and the outer spherical surface of the inner joint member, the track of the outer joint member The groove has an arc bottom having a center of curvature on the rotation axis of the outer joint member on the back side of the outer joint member, and a tapered bottom linearly expanding toward the opening end on the opening side of the outer joint member. Yes, and the curvature of the track grooves of the outer joint member With respect to a straight line connecting the center of the heart and the ball, the tapered bottom of the track grooves of the outer joint member is characterized in that as the operating angle becomes a right angle in the state of 0 °. The track groove of the inner joint member has a circular arc bottom having a center of curvature on the rotation axis of the inner joint member on the opening side of the outer joint member, and linearly toward the rear side of the outer joint member. The taper bottom of the track groove of the inner joint member is perpendicular to the straight line connecting the center of curvature of the track groove of the inner joint member and the center of the ball with the operating angle being 0 °. To be .
[0011]
As a result, in the present invention, the operating angle formed by the rotation shaft of the outer joint member and the rotation shaft of the inner joint member can be set to 52 ° at the maximum.
[0013]
Here, in the fixed type constant velocity universal joint of the present invention, the outer spherical center and the inner spherical center of the cage are offset to the opposite side by an equal distance in the axial direction with respect to the joint central plane including the ball center. By setting the cage offset amount (f) large, there is an advantage that the thickness can be improved by increasing the wall thickness on the inlet side of the cage into which the inner joint member is incorporated. In addition, since the wall thickness on the entrance side of the cage can be increased, it is possible to restrain the ball from popping out from the open end of the outer joint member by the cage pocket when the operating angle is taken.
[0014]
However, if the cage offset amount (f) is too large, (1) the amount of movement of the ball in the cage pocket increases in the circumferential direction, and the cage pocket has a larger circumferential dimension to ensure proper movement of the ball. As a result, the cage pillars become thinner and the strength becomes a problem. {Circle around (2)} The thickness on the back side, which is located on the opposite side of the cage from the entrance side, is reduced, and the strength is a problem.
[0015]
From the above, it is not preferable that the cage offset amount (f) is excessive, and there is an optimum range in which the significance of providing the cage offset amount (f) can be balanced with the problems (1) and (2). However, since the optimal range of the cage offset amount (f) varies depending on the size of the joint, it is necessary to obtain it in relation to the basic dimension representing the size of the joint. Therefore, the ratio (f /) of the cage offset amount (f) and the length (PCR) of the line segment connecting the center of curvature of the track groove of the outer joint member or the center of curvature of the track groove of the inner joint member and the center of the ball. PCR).
[0016]
Therefore, the cage offset amount in the present invention is such that the operating angle is 0 ° between the cage offset amount (f) and the center of curvature of the track groove of the outer joint member or the center of curvature of the track groove of the inner joint member and the center of the ball . It is set so that the ratio (f / PCR) to the line segment length (PCR) to be connected in the state is within a range of 0.017 to 0.133.
[0017]
If this ratio (f / PCR) is greater than 0.133, there is the problem of {circle around (1)} {2} above. Conversely, if it is less than 0.017, the significance of providing the cage offset amount (f) is lost. Therefore, from the viewpoint of securing cage strength and durability, the optimum range of cage offset amount (f) is that the ratio (f / PCR) is within the range of 0.017 to 0.133.
[0019]
Further, in the present invention, when the number of the balls is eight, the load applied to one ball can be reduced and the efficiency can be improved, and the strength, load torque and durability are excellent, and the ball diameter is also reduced. This is effective in that the entire joint can be reduced in size.
[0020]
Furthermore, in the present invention, it is desirable to form a pocket gap so as not to restrain the ball behind the cage pocket. In this way, the strength of the cage can be ensured even when the thickness of the rear side of the cage is reduced as the cage offset amount is increased.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of a fixed type constant velocity universal joint according to the present invention will be described in detail below.
[0022]
The fixed type constant velocity universal joint of the embodiment shown in FIGS. 1 to 3 has a mouth portion 24 in which a plurality of track grooves 22 are formed on an inner spherical surface 21 at equal intervals in the circumferential direction toward the opening end 23 along the axial direction. An outer joint member 25 having a plurality of track grooves 27 that are paired with the track grooves 22 of the outer joint member 25 on the outer spherical surface 26 along the axial direction at equal intervals in the circumferential direction, and an outer joint member 28. Between a plurality of balls 29 that transmit torque between the track grooves 22 and 27 of the joint member 25 and the inner joint member 28, and between the inner spherical surface 21 of the outer joint member 25 and the outer spherical surface 26 of the inner joint member 28. And a cage 30 for holding the balls 29. The plurality of balls 29 are accommodated in pockets 33 formed in the cage 30 and arranged at equal intervals in the circumferential direction.
[0023]
Here, FIG. 1 shows a state where the operating angle θ is 0 °, and FIG. 3 shows a state where the operating angle θ is the maximum angle (52 °). Although not shown, either the outer joint member 25 or the inner joint member 28 has a drive side rotation shaft, and the other has a driven side rotation shaft. The operating angle θ means an angle formed by the rotation axis X of the outer joint member 25 and the rotation axis Y of the inner joint member 28. Further, when the rotation axis X of the outer joint member 25 and the rotation axis Y of the inner joint member 28 take a certain operating angle θ other than 0 °, it is perpendicular to the bisector of the angle θ formed by both the rotation axes X and Y. This plane is called the joint plane P. When the operating angle θ is taken, if all the balls 29 are on the joint plane P, the distances from the ball center to both the rotation axes X and Y are equal, and therefore, the rotation axes X and Y are at a constant speed. Rotational motion is transmitted. An intersection of the joint 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.
[0024]
In the fixed type constant velocity universal joint of this embodiment, both the track grooves 22 and 27 of the outer joint member 25 and the inner joint member 28 have a structure capable of taking a large operating angle without any undercut. FIG. 4 shows an enlarged cross section (hatching is omitted) of FIG. 1 in order to explain the shapes of the track grooves 22 and 27 and the cage offset amount of the outer joint member 25 and the inner joint member 28, respectively.
[0025]
Each track groove 22 of the outer joint member 25 is formed at a predetermined depth from the inner spherical surface 21 of the outer joint member 25, and the depth gradually changes in the axial direction. The track groove 22 is connected to the arc bottom 22 a having the center of curvature O ₁ on the rotation axis X of the outer joint member 25 and the center of curvature O ₁ and the center O _{5 of the} ball 29 on the back side of the mouse portion 24. A taper bottom 22b that linearly expands toward the opening end 23 is formed on the opening side of the mouse portion 24 with a portion p where the line segment intersects the bottom of the track groove 22 as a boundary. The tapered bottom 22 b is formed at an angle that is perpendicular to a straight line connecting the center of curvature O ₁ of the track groove 22 of the outer joint member 25 and the center O _{5 of the} ball 29.
[0026]
Each track groove 27 of the inner joint member 28 is formed at a predetermined depth from the outer spherical surface 26 of the inner joint member 28, and the depth gradually changes in the axial direction. The track groove 27 connects, on the opening side of the mouse portion 24, an arc bottom 27 a having a center of curvature O ₂ on the rotation axis Y of the inner joint member 28, and the center of curvature O ₂ and the center O _{5 of the} ball 29. A taper bottom 27b that linearly increases in diameter toward the back end is formed on the back side of the mouse portion 24, with a region q where the line segment intersects the bottom of the track groove 27 as a boundary. The tapered bottom 27 _b is formed at an angle that is perpendicular to a straight line connecting the center of curvature O ₂ of the track groove 27 of the inner joint member 28 and the center O _{5 of the} ball 29.
[0027]
Thus, the opening side groove bottom of the track groove 22 of the mouth portion 24 of the outer joint member 25 is a tapered bottom 22b (for example, an expansion angle φ = 20 °) linearly expanded toward the opening end 23. Thus, an increase in operating angle θmax = 52 ° (conventional operating angle θmax + 2 °) was achieved without increasing the outer diameter of the mouth portion 24 of the outer joint member 25.
[0031]
The center of curvature of the outer spherical surface 26 of the inner joint member 28 and the center of curvature of the inner spherical surface 21 of the outer joint member 25 coincide with the centers of curvature O ₃ and O ₄ of the inner and outer spherical surfaces 31 and 32 of the cage 30, respectively. The centers of curvature O ₃ and O ₄ of the inner and outer spherical surfaces 31 and 32 of the cage 30 are offset from the joint center O by an equal distance f in the axial direction. Similarly, the center of curvature O ₁ of the track groove 22 of the outer joint member 25 and the center of curvature O ₂ of the track groove 27 of the inner joint member 28 are offset from the joint center O by an equal distance f in the opposite axial direction. ing. Therefore, a pair of track grooves 22 and 27 forms a wedge-shaped track whose interval gradually changes from one to the other in the axial direction. Each ball 29 is incorporated between a pair of track grooves 22 and 27 so as to be able to roll. When the outer joint member 25 and the inner joint member 28 transmit torque with the operating angle θ being taken, It receives the action of an axial force that tries to move it toward the wider interval.
[0032]
In this embodiment, in order to prevent the ball 29 from jumping out from the open end 23 of the mouth portion 24 of the outer joint member 25 when the operating angle θmax = 52 °, the cage can be restrained by the pocket 33 of the cage 30. The offset amount f is set larger than the conventional one. That is, the cage offset amount f, centroid radius value of the ball 29, i.e., the center of curvature center O ₂ and the ball 29 of the track grooves 27 of the center of curvature O ₁ or inner joint member 28 of the track groove 22 of the outer joint member 25 When the length of the line connecting O ₅ is PCR, f / PCR = 0.177 to 0.133.
[0033]
For example, since the cage offset amount f ′ in the conventional product (see FIG. 9 ) is 0.42 mm and the center locus radius value PCR ′ of the ball 9 is 25 mm, the cage offset amount f ′ and the center locus radius value of the ball 9 are The ratio with respect to PCR ′ (f ′ / PCR ′) was 0.017. On the other hand, when the maximum value of the cage offset amount f in the embodiment of the present invention (see FIG. 4) is 3.2 mm and the center locus radius value PCR of the ball 29 is 24 mm, the cage offset amount f and the center of the ball 29 are set. The ratio (f / PCR) to the locus radius value PCR is 0.133.
[0034]
Conventionally, increasing the cage offset amount f has been avoided due to concerns such as the ball 29 jumping out of the pocket 33 of the cage 30 on the back side of the cage 30 and the thickness of the back side of the cage 30 becoming thin. It was. FIG. 5 shows the joint strength (torsional strength) at the maximum operating angle with respect to the joint strength at the operating angle of 0 °, and the target level is reached even in the product of the present invention as in the conventional product. Therefore, there is no problem in terms of strength. Further, in the phase (phase angle 0 °) to be jump out ball 29 is best shown in FIG. 3, the force acting on the cage pocket conventional [FIG 6 (b)] is the force of the inlet side facing to some extent whereas had occurred, the present invention product [FIGS. 6 (a)] becomes apparent that less load on the cage 30 is hardly generated, further, when gradually increasing the cage offset amount f It was confirmed that this load applied to the cage 30 was reduced.
[0035]
In the fixed type constant velocity universal joint of this embodiment, it is preferable that the number of balls 29 held in the cage 30 is eight as shown in FIG. This 8-ball constant velocity universal joint can reduce the load applied to one ball and increase the efficiency, has excellent strength, load torque and durability, and can reduce the ball diameter. This is effective in that the entire joint can be reduced in size.
[0036]
Further, as shown in FIG. 3, it is desirable to form a pocket gap t so as not to restrain the ball 29 on the back side of the pocket 33 of the cage 30. In this way, even if the wall thickness on the back side of the cage 30 decreases as the cage offset amount f is increased, the cage 30 contacts the back side of the pocket 33 of the cage 30 to the back side of the cage 30. It is possible to mitigate damage and ensure the strength of the cage 30.
[0037]
【The invention's effect】
According to the present invention, 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 track groove of the outer joint member is paired on the outer spherical surface. An inner joint member in which a plurality of track grooves are formed along the axial direction at equal intervals in the circumferential direction, a plurality of balls that are interposed between both track grooves of the outer joint member and the inner joint member, and an outer joint In a fixed type constant velocity universal joint having a cage for holding a ball interposed between the inner spherical surface of the member and the outer spherical surface of the inner joint member, the track groove of the outer joint member is located on the back side of the outer joint member. an arcuate bottom whose center of curvature on the axis of rotation of the outer joint member in, towards its open end at the opening side of the outer joint member have a a tapered bottom linearly expanded, the outer joint member of the track groove For the straight line connecting the center of curvature and the center of the ball By tapering the bottom of the track grooves of the outer joint member is so operating angle is a right angle in the state of 0 °, without increasing the outer diameter of the outer joint member, to easily realize a high angle of working angle Therefore, the outer joint member can be made compact and the load capacity can be increased, and the needs for increased functionality and workability can be quickly met.
[Brief description of the drawings]
1 is a cross-sectional view showing a state where an operating angle is 0 ° in an embodiment of a fixed type constant velocity universal joint according to the present invention. FIG. 2 is a cross-sectional view taken along a line AA in FIG. FIG. 3 is a cross-sectional view showing a state in which the operating angle is a maximum angle of 52 ° in the embodiment of the present invention. FIG. 4 is a view for explaining the track groove shape and cage offset amount of the outer joint member in the present invention. FIG. 5 is a graph showing the joint strength at the maximum operating angle with respect to the joint strength at an operating angle of 0 ° . FIG. 6 shows the relationship between the phase angle of the ball and the force acting on the cage pocket. ) Is a characteristic diagram showing the case of the product of the present invention, (b) is a characteristic diagram showing the case of the conventional product. FIG. 7 is a sectional view showing a state where the operating angle is 0 ° in a conventional fixed type constant velocity universal joint . 8 is a cross-sectional view operating angle in conventional fixed type constant velocity universal joint showing the state of the maximum angle of 50 ° 9] Conventionally, sectional view for explaining the track groove shape and the cage offset amount of the outer joint member

Claims (5)

An outer joint member in which a plurality of track grooves are formed on the inner spherical surface at equal intervals in the circumferential direction toward the opening end along the axial direction, and a plurality of track grooves that are paired with the track grooves of the outer joint member are formed on the outer spherical surface. An inner joint member formed along the axial direction at equal intervals in the circumferential direction, a plurality of balls that are interposed between both track grooves of the outer joint member and the inner joint member, and an inner spherical surface of the outer joint member And a cage for holding the ball interposed between the outer joint member and the outer spherical surface of the inner joint member, the track groove of the outer joint member is on the axis of rotation of the outer joint member on the back side of the outer joint member. an arcuate bottom whose center of curvature on, possess a tapered bottom linearly diameter increases towards its open end at the opening side of the outer joint member, the center of curvature center of the ball track grooves of the outer joint member For the straight line connecting Fixed type constant velocity universal joint tapered bottom of the track grooves of the member is characterized in that as the operating angle becomes a right angle in the state of 0 °.   The outer spherical center and the inner spherical center of the cage are offset to the opposite side in the axial direction by an equal distance from the joint center plane including the ball center, and the cage offset amount (f) and the track groove of the outer joint member Or the ratio (f / PCR) of the length of the line segment (PCR) connecting the center of curvature of the track groove or the center of the track groove of the inner joint member and the center of the ball with the operating angle of 0 ° (f / PCR) is 0.017-0 The fixed constant velocity universal joint according to claim 1, wherein the fixed constant velocity universal joint is within a range of .133. Fixed type constant velocity universal joint according to claim 1 or 2, wherein the ball is eight. The fixed type constant velocity universal joint according to any one of claims 1 to 3 , wherein a pocket gap is formed so as not to restrain the ball at the back side of the pocket of the cage. Fixed type constant velocity universal joint according to any one of claims 1 to 4 formed operating angle of the rotation axis of the rotary shaft and the inner joint member of the outer joint member and having a maximum 52 °.

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