JPH0736184Y2 - Constant velocity universal joint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a constant velocity universal joint, and more particularly to a barfield type constant velocity universal joint.

[Conventional technology]

As a conventional Burfield type constant velocity universal joint, for example, the one having a structure shown in FIG. 6.28, page 349, of a power transmission device (Automotive Engineering Complete Book, Volume 9, Publishing Office; Sankaido Co., Ltd.) is known.

The joint of this configuration has a plurality of balls for transmitting torque,
The outer ring and the inner ring each have a ball rolling groove for rolling the ball, and a cage for holding the ball.

This will be described with reference to FIG. In the figure, if 1 is a ball, the outer peripheral surface of the inner ring (radius r _i1 ) and the inner peripheral surface of the outer ring (radius r _o1 ) are spherical surfaces having the same joint center O, whereas , Inner ring, outer ring ball rolling groove,
Each has an arc shape with different offset centers A and B. The ball 1 is held by the ball rolling groove and the cage in a plane where the center of the ball bisects the angle (joint angle) between the drive shaft and the driven shaft. At this time, the locus of the center of the ball 1 with respect to the change of the joint angle (hereinafter referred to as the ball center locus) has an arc a having a radius r ₉ and an offset center A and a radius r ₉ and an offset center B in the same figure. Arc b of these locus lines a,
b is designed to fit within the thickness of the cage. Here, the line segment AO, BO = E, and σ is the maximum axis intersection angle (maximum joint angle).

[Problems to be solved by the invention]

In such a conventional constant velocity universal joint, since the ball center loci a and b are two arcuate loci intersecting in the XOX plane, each ball is held even when an axial angle is attached. In order to achieve this, it is necessary that the ball center loci a and b fall within a range corresponding to the thickness of the cage in the radial direction, and in order to improve the locating property of the ball, XO
It is necessary to give a slight angle of intersection between the two trajectories a and b on the X plane.
Therefore, if the maximum axis crossing angle 2σ is set to be large while satisfying these conditions, the thickness of the cage becomes large, and the contact area between the ball and the ball rolling groove for good torque transmission becomes narrow. That is, as shown in FIG. 9, the force of the drive shaft is transmitted from the inner ring 2 to the outer ring 3 via the contact point m, the ball center p, and the contact point n. At this time, the angle θ formed by the center p and the point m or n is appropriately about 45 degrees, but when the cage 4 becomes thick, the contact point m goes inward and the contact point n goes out,
The contact points m and n enter the area unsuitable for torque transmission,
There is a problem that the efficiency of torque transmission is reduced unless a preload is applied between the ball 1, the inner ring 2 and the outer ring 3. On the contrary, in order to improve the efficiency of torque transmission, there is a contradictory problem that the maximum axis crossing angle 2σ must be set small.

Therefore, the present invention has been made by paying attention to such a conventional problem, and in particular, by adopting a configuration of compressing the radial movement amount of the ball center locus, the wall thickness of the cage is suppressed, It is an object of the present invention to provide a constant velocity universal joint capable of increasing the maximum axis crossing angle while maintaining the retaining property and the locating property.

[Means for solving problems]

In order to achieve the above object, the present invention provides an inner ring having a plurality of ball rolling grooves connected to one shaft, an outer ring having a plurality of ball rolling grooves connected to the other shaft, the inner ring and the In a constant velocity universal joint including a plurality of balls which are interposed between ball rolling grooves of an outer ring and transmit torque, and a cage which is interposed between the inner ring and the outer ring and holds the plurality of balls, each ball rolling The bottom cross-sectional shape of the rolling direction of the groove is formed into a complex curved shape of the same shape having an inflection point such as an arc or a straight line, and the inflection points of the rolling groove are symmetrically arranged in the rolling direction. The ball center locus with respect to the change of the joint crossing angle is arranged in a region corresponding to the thickness of the cage and is mirror-image-symmetric with respect to the power transmission surface.

[Action]

In this invention, the torque input to one shaft is transmitted at a constant speed to the other shaft via the inner ring (or outer ring), the ball, and the outer ring (inner ring). At this time, when both shafts have a joint angle, the ball moves along the ball rolling groove of the outer ring and the inner ring, and is urged toward the bottom cross-sectional shape in the rolling direction of this groove. The movement amount of is compressed.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, 10 is a Barfield type constant velocity universal joint, 12 is an input shaft (driving shaft), and 14 is an output shaft (driven shaft).

The constant velocity universal joint 10 includes an inner ring 16 connected to the input shaft 12, an outer ring 18 connected to the output shaft 14, and six balls 20 for transmitting torque interposed between the inner ring 16 and the outer ring 18. It has 20 and a cage 22 that holds each ball 20. here,
In the figure, O represents the joint center, and the axial direction passing through this center O is the Y axis, and the axis orthogonal to this Y axis is the X axis. Further, 24 is a dust boot and 26 is a tightening band.

The cage 22 has a partially cut spherical surface whose outer peripheral surface (radius r _o ) and inner peripheral surface (radius r _i ) have the same joint center O, and the inner peripheral surface of the outer ring 18 and the outer peripheral surface of the inner ring 16 are formed. It is slidably inserted between the surfaces.

The inner race 16 has ball rolling grooves 16a, ..., 16a corresponding to the balls 20, ..., 20 for rolling the balls 20 respectively.
Are formed. Similarly, the outer race 18 is also formed with ball rolling grooves 18a, ..., 18a. Each of these ball rolling grooves 16a and 18a is formed in a substantially semi-circular shape, although the cross section orthogonal to the ball rolling direction has a predetermined torque transmission angle, and the ball rolling direction at the ball contact point. As shown in FIG. 2, each of the cross-sectional shapes of
A circular arc R and a straight line segment L are formed to be connected to each other through. At this time, the ball rolling grooves 16 facing each other
In a and 18a, the shapes of the bottom surfaces are opposite in the rolling direction, so that one ball 20 can be held.

Each arc R has an offset center A or B separated from the joint center O on the Y axis by a distance E and a predetermined radius. Further, each inflection point H is an offset center parallel to the power transmission surface XOX when the joint angle is zero as shown in FIG.
A perpendicular line is drawn from A and B, and the perpendicular line and the arc R intersect each other. Further, each line segment L is formed parallel to the YOY axis from its inflection point H when the joint angle is zero.

Therefore, the ball center locus of the balls 20, ..., 20 with respect to the change of the joint angle is, as shown in FIG. ₃ , a compound curve of the arcs c ₁ c ₂ and line segments c ₂ c ₃ (hereinafter, A center locus c) and a complex curve of arcs d ₁ d ₂ and line segment d ₂ d ₃ (hereinafter referred to as ball center locus d). These ball center loci c and d are the above-mentioned compound curve R + L.
Of the joint 10 and the bisecting surface XO of the joint 10.
It has a mirror image symmetry with respect to X (power transmission surface). Therefore, constant-speed rotation can be transmitted from the input shaft 12 to the output shaft 14 via the joint 10.

Next, the function and effect of the first embodiment will be described.

Since the ball center loci c and d are contained in the area corresponding to the thickness of the cage 22, even if an axis angle is attached, the ball
20,…, 20 are held accurately. Then, when the input shaft 12 rotates, this rotational force is applied to the inner ring 16, balls 20, ..., 20, outer ring 18.
Is transmitted to the output shaft 14 via. At this time, the above-mentioned ball center loci c and d are bisected plane XOX (power transmission surface)
Since they are mirror images of each other, the balls 20, ..., 20 are on the ball center locus c or d not only when the two axes are in a straight line state as shown in Fig. 1 but also when a joint angle is attached. Can be moved to transmit uniform rotation.

Further, in this embodiment, the shape of the bottom surface in the rolling direction at the contact points of the ball rolling grooves 16a and 18a is a compound curve having the inflection point H, and the ball center loci c and d are the wall thicknesses of the cage 22. Since it fits within the range equivalent to
Even when the same maximum axial intersection angle 2σ as that of the conventional joint is set (see FIGS. 8 and 3), the radial movement amounts of the ball center loci c and d are compressed as compared with the conventional joint. That is, the thickness of the cage 22 can be reduced accordingly.

This is shown by a numerical example. The theoretical outer diameter r _o1 and inner diameter r _i1 of the conventional joint shown in FIG. 8 are r _o1 = E · sinσ + [(E · sinσ) ² + (r _g ² −E ² ). ]
^1/2 r _i1 = -E · sin σ + [(E · sin σ) ² + (r _g ² −
E ² )] ^1/2 . On the other hand, the theoretical outer diameter r _o2 and inner diameter r _i2 of the joint 10 according to this embodiment are r _o2 = r _o1 r _i2 = (r _g ² −3E ² ) ^1/2 . Therefore, specifically, the distance E = 4 mm and the radius r _g = 34 m
Substituting m, angle σ = 22.5 °, r _o1 = 35.33 mm, r _i1 = 32.
27 mm, r _i2 = 33.29 mm, therefore the theoretical thickness of the cage of the conventional joint is r _o1 −r _i1 ≈3 mm, while the theoretical thickness of the cage 22 of the joint 10 of this embodiment is r _o2- r _i2 ≈ 2 mm. Therefore, if the thickness margins Δ inside and outside the cage are each set to 2 mm and added, the actual thickness of the cage of the conventional joint is about 7 mm, and the actual thickness of the cage 22 of the joint 10 according to the present embodiment is about 6 mm. And can be made thinner by about 1 mm.

That is, while the constant speed rotation condition is satisfied, the wall thickness of the cage 22 can be reduced, and sufficient contact can be secured for torque transmission between the ball 20 and the ball rolling grooves 18a and 16a facing the ball 20, As a result, the maximum axis crossing angle 2σ can be set excessively.

Further, in the present embodiment, since the intersection angle of the ball center loci c and d at the intersection point P is the same as that of the conventional joint, the locating properties of the balls 20, ..., 20 do not change.

In the above embodiment, the line segment L does not have to be parallel to the axis YOY. For example, in the ball center loci c and d, the ball may be a straight line or a curve tangent to the inflection points c ₂ and d _2. The rolling grooves 16a, ..., 16a and 18a, ..., 18a may be formed. Further, in order to secure the rigidity of the cage 22 to some extent, the positions of the inflection points H and H (that is, c ₂ and d ₂ ) are not limited to those described above, and the positions may be changed appropriately, The thickness of the cage 22 may be secured to some extent.

Next, another embodiment of the present invention is shown in FIGS. These examples have the same configuration as in FIG. 1 (hence the same reference numbers are used for the same components),
The ball rolling grooves 16a, ..., 1 of the inner ring 16 and the outer ring 18 are arranged so that the ball center loci become those shown in FIGS. 4, 5, and 6, respectively.
6a and 18a, ..., 18a are formed.

First, in FIG. 4, r _o3 is the theoretical outer diameter of the cage 22, r
_i3 is an inside diameter of the theoretical cage 22, a composite curve f connecting the intersection points e ₁ to e ₃ complex curves e and the points of intersection f ₁ ~f ₃ connecting an example in which a ball center trajectory. That is, the points e ₂ and e ₃ and f ₂ and f ₃ are bent at appropriate angles so that the loci e and f do not go out of the cage.

Further, in FIG. 5, g ₁ and h ₁ are inflection points, and the whole ball center locus g and h is a smooth ball center locus through these inflection points g ₁ and h ₁ , and this is the wall thickness of the cage. It is contained in a considerable area. r
_o4 and r _i4 are the theoretical outer diameter and inner diameter of the cage 22. In this way, by smoothing the loci g and h, the ball 20
It is possible to avoid such a situation that the contact with the contact becomes a two-point contact. This can also be applied to the curves in the above figures.

Further, FIG. 6 shows a ball center locus i having inflection points i ₁ and i ₂ and a ball center locus j having inflection points j ₁ and j _2.
And the locus on the inner diameter side of the intersection P is the same as that shown in FIG. 4, and is set so as to extend outward from the inflection points i ₁ and j ₁ in parallel to the axis YOY. Along with that, the whole is smoothed.

FIG. 7 shows an example of a cross section in the rolling direction of the ball rolling groove 18a of the outer ring 18 formed by the method of FIG. This 7th
In the case of the figure, the ball rolling groove 18a is formed by forging and the cage 2
The second guide spherical surface 22A is formed by cutting. As can be seen from FIG. 7, when the ball rolling groove 18a is finished by cold forging, the forging die cannot be removed with the one shown in FIG. 1 described above, but in the example shown in FIGS. Will be possible. In this case, the theoretical outer diameter r _o5 of the cage 22 becomes larger, but instead, the inner diameter r _i5 can be made larger than in the case of FIG. 1 (direction to make the cage 22 thinner). When calculated according to the embodiment shown in FIG. 3, the thickness can be 3.5 mm.

In addition, in the examples of FIGS. 6 and 7, the thickness of the cage 22 is slightly increased, but in order to improve the forging die removal,
It is also possible to make the straight lines of the loci i and j open slightly with respect to the axis YOY. Further, the guide spherical surface 22A may be configured such that the mouth of the bell expands inside the cage inner diameter as shown by a virtual line in FIG.

[Effect of device]

As described above, according to the present invention, since the radial movement amount of the ball center locus in the rolling groove is compressed as compared with the conventional one, it is possible to reduce the thickness of the cage and hold the ball. There is an effect that the maximum axis crossing angle can be set to be larger while securing the property and the locating property.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view showing ball rolling grooves of an outer ring and an inner ring in FIG. 1, and FIG. 3 is an embodiment of FIG. FIGS. 4 to 6 are explanatory views showing the ball center locus in each of the other embodiments of the present invention, and FIG. 7 is an illustration of the outer ring formed by the method shown in FIG. FIG. 8 is a partial sectional view showing a ball rolling groove, FIG. 8 is an explanatory view showing a ball center locus according to a conventional example, and FIG. 9 is a rolling direction for explaining a torque transmission angle between an outer ring and an inner ring and a ball. It is a fragmentary sectional view of the direction orthogonal to. In the figure, 10 is a constant velocity universal joint, 12 is an input shaft (shaft), 14 is an output shaft (shaft), 16 is an inner ring, 18 is an outer ring, 16a, ..., 16a, 18a, ..., 1
8a is a ball rolling groove, 20, ..., 20 are balls, and 22 is a cage.

Claims (2)

[Scope of utility model registration request] 1. An inner ring connected to one shaft and having a plurality of ball rolling grooves, an outer ring connected to the other shaft and having a plurality of ball rolling grooves, and a ball rolling groove of the inner ring and the outer ring. In a constant velocity universal joint including a plurality of balls interposed therebetween for transmitting torque, and a cage interposed between the inner ring and the outer ring for holding the plurality of balls, a bottom of each ball rolling groove in the rolling direction is provided. The cross-sectional shape is formed into a compound curved shape of the same shape having an inflection point such as an arc or a straight line, and the inflection points of the rolling groove are arranged symmetrically to each other in the rolling direction, so that the joint crossing angle A constant velocity universal joint characterized in that a ball center locus with respect to a change is in a region corresponding to the thickness of the cage and is mirror image symmetrical with respect to a power transmission surface. 2. The composite curve has an arbitrary number of inflection points,
The constant velocity universal joint according to claim 1, which is a utility model registration which is a composite curve formed by connecting arbitrary curves or straight lines with this inflection point as a boundary.