DE4344982C1 - Synchronising rotary joint for vehicle steering trains - Google Patents

Abstract

The rotary joint has two substantially similar articulated joint components centred relative to each other and supported against each other with two axially extending projections. The outer torque-transferring rolling bodies (421,422) are kept at a constant distance from each other over the entire bending angle range of the joint. The centre longitudinal axis of each rolling body track (417,418,419,420) comprises two circular curves, the first with the centre (M1,M2) on the longitudinal axis (A1,A2) of each joint half and the second with the centre (M1',M2') offset from the longitudinal axis (A1,A2) and with a smaller radius (r-s) than the first radius (r) so that a continuous transition arises for the two curves.

Description

The invention relates to a rolling element constant velocity universal joint with two substantially identical joint components which are held centered against one another and are mutually supported in the direction of rotation with projections extending substantially in the axial direction, with the projections being approximately radial in length through the longitudinal axes A 1, A 2 of the joint components Flanks are formed, in which approximately longitudinal rolling body paths run, which are assigned to one another in pairs and viewed in longitudinal section when the joint is stretched form a control angle with one another for torque-transmitting rolling elements contained therein, and the rolling element paths in both joint components viewed in longitudinal section are so curved that the steering angle α _e remains essentially constant over the flexion angle β of the joint.

Joints of the type mentioned are known from FR 1 157 482, especially in the form of three-roller joints. The two External rolling elements are used together with a centering ball, at the intersection of the longitudinal axes of the joint components in up is held, guided on a common bolt. The two external rolling elements are slidable on the bolt held. The opposite rolling element tracks form in Longitudinal section considers a crossing winch kel α, which changes depending on the joint flexion angle β different. This change is strongly related to the shape of the Rolling element tracks. FR 1 157 482 shows two main arrangements.  

The first has straight lanes connected with a very poor control of the rolling elements. The second shows curved ones Paths, axially offset from each other, and offers a substantial improved control. But there are other disadvantages here especially excessive friction, very precise demands on fer tolerance and cumbersome installation.

Proceeding from this, the present invention has the object to create a joint of the type mentioned at the beginning, whose friction conditions are improved, especially for the use as a joint in vehicle steering lines. The solution this is that the rolling element tracks in both Ge Steering components viewed in longitudinal section are designed in such a way that the distance between the two rolling elements over the total th range of the articulation angle of the joint remains constant.

Because of the constant distance and the corresponding favorable frictional relationships between rolling elements and rolling element tracks as well as between rolling elements and guide Bolting is a prerequisite for a functionally reliable joint given, especially for applications that have a low friction torque relative to the total torque. Under the specified ne regulations apply to different courses; a preferred one simple design is that the central longitudinal axis each rolling element track consists of two arcs, the first with the center on the longitudinal axis A₁, A₂ each half of the joint and the second with the center so offset to the longitudinal axis A₁, A₂ and with a smaller radius than the first one continuous transition of the two arcs results.

The consideration of the distance between the rolling elements alone in relation to the frictional forces on the rolling elements simplified view. Another influence is through the  Shape of the rolling element tracks in their cross section perpendicular to their central longitudinal axis as well as by the preload between Rolling elements and rolling element tracks in a free-standing state given.

In an advantageous embodiment it is provided that the rolling elements perbahnen in cross-section to their central longitudinal axis Contour that the contact between rolling element tracks and Rolling elements are made in two points, half contact have angle δ which is always greater than or equal to 40 °. Farther, to prevent slippage between the rolling element tracks and rolling elements minimize the distance between the outer and inner cones cycle tracks of the rolling element tracks should be as small as possible without to adversely affect the rolling stability of the rolling elements.

A further favorable embodiment is that the joint for centering has a centering ball which is located in the Weil on the longitudinal axis of each of the joint components, the ball seats. It can be provided that the ball receptacles are each conical on the inside and form a half contact angle δ _m with the centering ball, which is greater than or equal to 40 °.

It is advantageous if the centering ball and the two au external rolling elements by means of both rolling elements and the Centering ball penetrating guide pin on a common sam axis are guided, with a relative displacement possible between the centering ball and the two external rolling elements is. Furthermore, it is favorable if the ball mounts for the centering ball in inserts supported by spring means Articulated components are formed, the pretensioning of the ferti gung tolerance-related game.  

It is possible that the two outer rolling elements as through drilled rollers are formed. Furthermore, the rolling elements represent cylindrically overturned spherical bodies. In addition can the rolling elements flattened at both ends perpendicular to the axis his. These are friction-reducing and weight-reducing measures.

The manufacturing tolerances for each half of the joint between rolling elements tracks and opposite centering ball admission be very low. A possible play in the assembled joint between rolling elements and rolling element tracks or centering ball run can be taken up by two preloaded springs between the balls men and their contact surfaces in the joint components under nied higher joint drive torque can be compensated. this applies in the event that a guide pin is used. If not Guide pin is used is just a preloaded spring required. The compromise between spring preload and The torque of the joint is selected depending on the application become.

The configurations designated here are particularly suitable for a swivel in a steering column, in which relatively small Circulation speeds and low torques occur. Before Simple, inexpensive production is advantageous here. Around the unloaded external rolling elements in their control one is supported by the two torque-transmitted Rolling elements and the centering ball inserted guide pin provided such that the outer rolling elements relative to the Zen trierkugel are displaceable. To reduce the forces are here, for example, low-friction guide pressed into bores to provide sleeves with favorable storage properties. The zen Trierkugel can be axially pressed onto the bolt or can be slidable on the bolt if the two outside rolling elements are axially fixed on the bolt. The recordings for the  Centering balls are advantageously designed to be low-friction ten, which is also achieved by a corresponding coating can be.

A series assembly of a joint according to the previous state of the Technology is quite time-consuming and therefore expensive. This is particularly the case when the joint is without spring-loaded Preload force should work on the rolling elements. As a very effective and inexpensive installation aid should at least one of the two centering ball receptacles formed as a separate component his. The recess for the centering ball consists of a half of the inner cone seat supplemented by a straight V-shaped Ku gelbahn, which runs continuously to the outer wall of the recording and in Course is carried out perpendicular to the axis of rotation of the recording. The Position of the track axis of this ball track is for the purpose of assembly two joint components inclined to the longitudinal axis of your own Joint component. After assembly, the ball holder is rotated, until their track axis is parallel and the ball track with their in the Opening facing the outer wall facing its own joint component and then secured against rotation.

It is therefore envisaged that at least one centering ball me with a semi-conical seat is to which the V-shaped ball track connects, which is as an open groove perpendicular to the pivot axis of the joint extends, with one remaining toward the open end of the groove fend opening angle between the longitudinal axis of the joint component and the bottom of the groove is provided. In particular, it is featured hit that the centering ball mount is perpendicular to the axis of the associated joint component has a rotating axis of rotation, which are set in a rotary position for the assembly process is, and in a different rotational position in an anti-rotation Way is set properly.

A preferred embodiment and a representation of the Angular requirements and centering ball recording according to the invention in Comparison with a joint according to the prior art is in the Drawings shown.

Fig. 1 shows a ball joint of the generic type according to the prior art;

Fig. 2 shows a longitudinal section through a joint in the plane of the rolling element tracks according to the prior art;

Fig. 3 shows a longitudinal section perpendicular to Fig. 2;

Fig. 4 shows a longitudinal section of the track geometry of a joint according to the invention;

Fig. 5 shows the cross section through a path of the outer lying the torque-transmitting rolling element under drawing the contact angle δ _{a of} a joint according to the invention;

Fig. 6 shows a cross section through the ball seat of the centering under delineation of the contact angle δ _m;

Fig. 7 shows a cross section through the joint with individual units for centering ball holder;

Fig. 8 shows two hinge components flexed to each other before assembly. The right joint component is preassembled with the two external rolling elements, centering ball and guide pin. The left joint component has a separate centering ball seat in its mountable position;

FIG. 9 shows two joint components assembled with one another in longitudinal section with the centering ball receptacle according to FIG. 8 in its end position. A locking pin between the receptacle and the joint component provides the anti-rotation device.

In Fig. 1 a joint according to the prior art in demon tiert arrangement is shown in perspective. Two joint components 11 , 12 each have two projections 13 , 14 and 15, 16 extending in the axial direction, in each of which rolling element tracks 17 , 18 and 19 , 20 , which are at an angle to the longitudinal axis of the respective joint component, are only hinted at . According to "Joints and cardan shafts", p. 234, Springer Verlag 1988, the angle to the longitudinal axis should be approximately 12 °. The rolling element tracks are each open to the same side in relation to a longitudinal plane through the longitudinal axis of each joint component. The rolling element tracks 17 , 19 form a first crossing pair of tracks for receiving a first ball 21 transmitting torque in one direction of rotation; the roller body tracks 18 , 20 form a second pair of tracks which intersect to receive a ball 22 which transmits torque in the opposite direction of rotation. The joint components 11 , 12 have further projections 23 , 24 , in each of which a not recognizable Kugelausneh tion 25 or a recognizable ball recess 26 are formed for receiving a centering ball 27 . For this purpose, a common bolt 28 is pushed through the three balls 21 , 22 , 27 to guide the three balls exactly on one axis. At least the torque-transmitting balls 21 , 22 are axially slidable ver on the bolt relative to the centering ball, while the centering ball 27 can be pressed firmly. From the designated designation it is clear that due to the insufficient outer ball guide with acceptable maximum preload at the joint shown, there is free access when the direction of rotation is changed, which deteriorates with increasing drive torque.

This makes the joint suitable for vehicle steering locked out.

In Fig. 2, also prior art, a longitudinal section through a joint similar to that shown in Fig. 1, but with GE curved rolling element tracks, a first joint component 211 and a second joint component 212 with their axes A 1, A 2 forming a bending angle β . On the hinge component 211 , the protrusions 213 , 214 extending in the direction of the axis A 1 and 214 and the protrusions 215 , 216 extending on the hinge component 212 extending in the direction of the axis A 2 can be seen. For systematic reasons, no distinction is made here as to which of the projections lie in front of and behind the diffraction plane. All essential lines are projected onto the diffraction plane. The intersection of the axis A₁, A₂ is designated M as the center of the joint. This simultaneously forms the center position of a centering ball 227 , the holding arms 223 , 224 of which are located in front of or behind the diffraction plane are shown in section in the region of their transition.

In Fig. 2, the projections 213 , 214 with curved Wälzkör perbahnen 217 , 218 can be seen , whose central longitudinal axes lie on a common circle K₁; ie the rolling element tracks are curved in the shape of a circular arc, the center of curvature M 1 lying on the longitudinal axis A 1 of the joint component 211 and the center M of the joint having an axial distance. There are also the curved rolling element tracks 219 , 220 in the projections 215 , 216 of the second of the joint components 212 , the center of which lies on a common circle K₂, the center point M₂ of which is the same distance from the center of the joint M as the center M₁ which, however, lies on the longitudinal axis A₂. Due to the aforementioned geometry, the control angle between the path center lines corresponds to the intersection angle between the two arcs K 1, K 2 and the intersection angle of the perpendicular to the circle tangent.

In the given case, this is approximately 37 °. It gives way when circulating of the joint in all planes only a little bit from those shown here Sizes on the outside of the cutting angle of the axes A₁, A₂ and on the inside of the cutting angle of the axes A₁, A₂ only little off. The bolt that the two external rolling elements and one Ball leads to each other is not shown for simplicity.

Fig. 3 shows the same joint at a flexion angle β of approximately 35 ° and perpendicular to the plane in Fig. 2. The outer rolling element, which is under torque load, tries to tend to the gaping web side - to the right. Depending on the size of the steering or path crossing angle α, the ball is increasingly held against this tendency. A crossroads angle of approx. 40 °, however, at its higher deflection angle β of over 30 ° in its sole effect, does not yet provide sufficient ball guidance. The pin 328 transfers a portion of the rightward force component on the non-loaded outer ball to the opposite outer ball, which thereby tends to the left, in the direction of the converging rolling element tracks which serve as a stop. The combination of a substantially constant web crossing angle of up to approximately 40 ° and the force transmission function of the bolt 28 provides the necessary control of the outer rolling elements. A track crossing angle of more than approx. 40 ° improves the rolling element control visibly, al however with a certain disadvantage with regard to the outer joint dimensions and the friction of the outer rolling elements in the tracks and on the bolt. A good compromise between rolling element guidance and minimizing friction lies at a control or web crossing angle α of approximately 50 °.

With a rotating joint, the ball and rolling element friction and their minimization can be represented as follows:
The centering ball is subjected to an orbital movement opposite the center projections 323 , 324 . With a suitable grease and surface treatment, the friction conditions are acceptable. There is a sliding movement between the centering ball and the guide pin in accordance with the bending angle and the path crossing angle. This can also be mastered in the same way.

There is a small one between the outer rolling elements and the guide pin Sliding movement. As an example, with a crossing angle of 40 ° and bending angle of 40 ° changes the distance between the External rolling elements by 0.8% twice per revolution. The little Ab The change in level is not easily continuous under load to compensate and this creates undesirable friction.

The invention according to FIG. 4 relates to a path design, which keeps the distance between the rolling elements constant and thus eliminates the small sliding movements.

Expressed mathematically, the following results:

provided
β = bending angle,
α₀ = crossing angle in the stretched state,
= Distance of rolling elements when stretched,
= Distance of rolling elements when bent,
then

so if β <0.

A modified curvature of the tracks, due to a radia len offset s of the center M₁ ', M₂', the radius of curvature for part of the tracks according to Fig. 4, gives certain constant conditions over the entire Beu angle range under certain conditions.

The constructive execution corresponds within a vernach acceptable deviation of the required correction from the formula above.

From Fig. 4 it follows that the offset s is generally expressed s = 0.314 r sin α₀.

The outer rolling elements, as shown in FIG. 5, guided by two contact points per path, are exposed to a certain amount of slip due to the different inner and outer radii of the path curvature. This can be reduced by reducing the distance between the contact points on the inner and outer radii. The size of the reduction should not affect the stability of the external rolling elements on the guide pin. For this purpose, lends itself to Fig. 5 with b / D = 0.9 is a good compromise.

When using a guide pin, the shape is the two external rolling elements are not limited to a spherical shape. Pierced rollers with a geometric shape are also suitable for this correct contact points to the railways. Cost and space advantages are possible. Is only as a central centering element a ball the most sensible shape.

In Fig. 5518519 is a cross section through one of the rolling body races 517, 520 shown according to the invention with one of the torque transmitted Außenwälzkörper 521, 522. The rolling element radius R _{K is} shown with an arrow. The flanks of the path are formed by arcs, whose centers M _B , M _B 'are offset from the center of the rolling element M and thus from the center axis of the path, the radii of curvature R _B , R _B ' each being about 5% larger than R _K are. This results in half contact angles α _a with respect to the median plane of the web which are equal to or greater than 40 °.

Fig. 6 is also a part according to the invention and shows a section through the recess for the centering ball 627 , which is shown in phantom. The ball receptacles 625 , 626 are opened conically for the sake of design simplification, with a half contact angle of δ _m equal to or greater than 40 ° relative to the center plane being provided. The inner cone is so deep that contact with the ball is avoided at the bottom.

In Fig. 7 shows a cross section through a joint according to the invention along the axis of a guide pin 728 , on which the centering ball 727 is held axially displaceable, while the outer rolling elements 721 , 722 are preferably rotatable but not slidable ver. The projections 713 , 714 and 723 of a first joint component and 715, 716 and 724 of a second joint component are shown in cross section. The tracks 717 , 718 can be seen in the projections 713 , 714 and the tracks 719 , 720 in the projections 715 , 716 in cross section. To compensate for a Wälzkör perspiels due to manufacturing tolerances are cracks in the pre 723, 724 ball-bearings 729, 730 set vertically movable with the bolt 728, which are supported resiliently on disc springs 731, 732 to this, a possible play of the rotary moment transmitted Außenwälzkörper 721, 722 to be able to compensate. In the ball receptacles 729 , 730 in cross-section the recesses 725 , 726 for the centering ball 777 leads directly out. The preload of the disc spring will be in accordance with the application requirement and should be set as low as possible anyway. In the case of a joint for a steering column of a vehicle, this preload is intended to withstand the steering requirements in normal road traffic. Higher loads, e.g. B. yawning when Ran, the springs will press on block.

In Fig. 8, two hinge components are shown in a mutually inclined position for final assembly. The right hinge construction part 812 has an arrangement with a permanently integrated centering ball socket, which is not visible. Rolling body races between the outer and the ball receiving are in vormon sembled the two Außenwälzkörper, the centering and guide pin 828th The left joint component 811 shows the new centering ball receptacle 879 suitably inclined for pushing together with the right joint half 812 . The ball seat 879 is also shown in the end position, but separate from the joint, and is designated 880 there.

Fig. 9 shows two joint components 911 , 912 in longitudinal section assembled together with centering ball 927 , guide pin 928 and an almost covered outer roller body 922 . The second outer roller body 921 is shown loosely. The rotation lock is effected here with pin 934 in the bore 935 . Certain other anti-rotation arrangements can also be used here.

Reference numbers that are not named designate parts that are named with Divide with the same last two decimal places voices.

Reference list

11 , 211 , 311 , 811 , 911 joint component - left
12 , 212 , 312 , 812 , 912 joint component - right
13 , 213 , 313 , 713 outer track projection - left
14 , 214 , 314 , 714 outer track projection - left
15 , 215 , 715 outer track projection - right
16 , 216 , 716 outer track projection - right
17 , 217 , 317 , 417 , 517 , 717 outer track - left
18 , 218 , 318 , 418 , 518 , 718 outer track - left
19 , 219 , 319 , 419 , 519 , 719 outer track - right
20 , 220 , 320 , 420 , 520 , 720 outer panel - right
21 , 221 , 321 , 421 , 521 , 721 , 821 , 921 external rolling elements
22 , 222 , 322 , 422 , 522 , 722 , 822 , 922 external rolling elements
23 , 223 , 323 , 723 center projection - left
24 , 224 , 324 , 724 center projection - right
25 , 625 , 725 ball recess - left
26 , 626 , 726 ball recess - right
27 , 227 , 327 , 427 , 627 , 727 , 927 centering ball
28 , 328 , 728 , 828 , 928 bolts
729 , 929 ball holder - left
730 ball holder - right
731 disc spring
732 disc spring
934 ball-bearing pin
935 hole for pin
879 ball holder - left (mounting position)
880 ball holder - left (completion)
A₁ longitudinal axis
A₂ longitudinal axis
K₁ circular path
K₂ circular path
M center of the joint
M₁ center of curvature (r)
M₂ center of curvature (r)
M₁ ′ center of curvature (rs)
M₂ ′ center of curvature (rs)
B, B ′ sphere center
C, C ′ center of the sphere

Claims (12)

1. constant velocity universal joint with two substantially similar joint components which are kept centered against each other and each with two essentially in the axial direction extending projections mutually support each other in the direction of rotation, with the projections approximately in radial planes through the longitudinal axes A₁, A₂ Joint components extending flanks are formed, in which approximately longitudinal rolling body paths run, which are assigned to one another in pairs and viewed in longitudinal section when the joint is extended, form a control angle with one another for two torque-transmitting outer rolling elements accommodated therein, and wherein the rolling element paths in both joint components are viewed in longitudinal section run so curved that the control angle α _e remains essentially constant over the articulation angle β of the joint, characterized in that the outer rolling elements ( 421 , 422 ) are at a constant distance from one another above the hold the entire area of the joint angle. 2. Joint according to claim 1, characterized in that the central longitudinal axis of each roller track ( 417 , 418 , 419 , 420 ) consists of two arcs, the first with the center M₁, M₂ on the longitudinal axis A₁, A₂ of each joint half and the second with the Center point M₁ ', M₂' so offset to the longitudinal axis A₁, A₂ and with a smaller radius (rs) than the first radius r that there is a continuous transition of the two circular arcs, the offset s on the path radius r₀ at the center point B of the rolling element , C is plotted with the joint stretched and the two arcs each extend to a different side from this path radius r₀, with a ratio of the radii of s = 0.314 r sin α₀, where α₀ is the path crossing angle when the joint is stretched. 3. Joint according to claim 1 or 2, characterized in that the rolling element tracks ( 517 , 518 , 519 , 520 ) in cross section to their central axis have a contour deviating from a circular shape, the contact with the torque-transmitting rolling elements ( 521 , 522 ) in each path in two points, which have a half contact angle α _a , which is always greater than or equal to 40 °. 4. Joint according to one of claims 1 to 3, characterized in that the joint for centering has a centering ball ( 627 ), which was received in each lying on the longitudinal axis A₁, A₂ of each of the joint components Kugelauf. 5. Joint according to claim 4, characterized in that the ball receptacles ( 729 , 730 ) are each conical and form with the centering ball ( 727 ) a half con tact angle δ _m , which is greater than or equal to 40 °. 6. Joint according to claim 4 or 5, characterized in that the centering ball ( 727 ) and the two outer rolling bodies ( 721 , 722 ) by means of an all three penetrating bolt ( 728 ) are guided on a common axis, with relative displacement between the Centering ball ( 727 ) and the two outer rolling elements ( 721 , 722 ) is possible. 7. Joint according to one of claims 4 to 6, characterized in that the ball receptacles ( 729 , 730 ) for the Zentrierku gel ( 727 ) as spring-supported inserts in the middle projections ( 723 , 724 ) of the joint components are formed, the bias starts the game due to manufacturing tolerance. 8. Joint according to claim 6, characterized in that the two outer rolling elements ( 721 , 722 ) are arranged as perforated rollers. 9. Joint according to one of claims 1 to 8, characterized in that the outer rolling bodies ( 721 , 722 ) are cylindrical via rotated spherical bodies. 10. Joint according to claim 9, characterized in that the outer rolling bodies ( 721 , 722 ) are flattened at both ends perpendicular to the cylinder axis. 11. Joint according to one of claims 1 to 4, characterized in that at least one centering ball receptacle ( 879 ) is provided with a semi-conically limited seat which continues in a V-shape as an open groove at the end, one towards the open end of the groove extending öff nender angle between the longitudinal axis A₁ and the bottom of the groove is provided. 12. Joint according to claim 11, characterized in that the centering ball holder ( 879 ) has a perpendicular to the longitudinal axis A of the associated joint component ( 811 ) axis of rotation Z and is set in a rotational position for the Mon day operation, and in a different rotary setting in is set against rotation in a functional manner.