Bearing assembly for a journal, especially of a cross member of a universal joint

A bearing assembly for a bearing journal (13), especially of a cross member of a universal joint, has a bearing journal (13) with a cylindrical outer face (14), an end face (16) and a journal axis (15). A bearing element (8) has a cylindrical bearing bore (9) with a bottom face (11) and a running face (10) which is arranged at a radial distance from the outer face (14) of the bearing journal (13). Rolling-contact members (17), at their respective ends, include at least partially planar first end face (18) and second end face (19). The faces (18) and (19) are arranged between the running face (10) and the outer face (14). A stop face (20) includes an annular contact face (21) for the first end face (18) of the rolling-contact members (17). A pressure disk (22) is included with a disk portion (23) arranged between the end face (16) of the bearing journal (13) and the bottom face (11). A supporting portion (24) radially follows the disk portion (23) with reference to the journal axis (15). The supporting portion (24) is contacted by the second end faces (19) of the rolling-contact members (17). The supporting portion (24) is designed to be resilient.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to German Patent Application No. 10155761.2 filed Nov. 14, 2001, which application is herein expressly incorporated by reference.

FIELD OF THE INVENTION

The invention relates to a bearing assembly for a bearing journal of a cross member of a universal joint.

BACKGROUND OF THE INVENTION

A bearing assembly is described in U.S. Pat. No. 6,077,166 A. The bearing journal has a cylindrical outer face, an end face and a bearing axis. A bearing element is placed onto the bearing journal. The bearing element has a cylindrical bearing bore with a bottom face and a running face. The running face is arranged at a radial distance from the outer face of the bearing journal. Rolling contact members are positioned between the bearing journal and the bearing element. The rolling-contact members are cylindrical along at least part of their length. The rolling contact members, at their ends, have a planar first end face and a planar second end face. The end faces are arranged between the running face and the outer face around the bearing journal to form a collar.

A seal attached to a metallic carrier is inserted into the open end of the bearing bush. The metallic carrier has a web angled towards the journal axis and forms an annular contact face for the first end face of the rolling-contact members. A pressure disk is positioned between the end face of the bearing journal and the bottom face of the bearing bush. The pressure disk is fully supported on the bottom face and on the end face. The pressure disk projects radially and axially into the gap between the running face of the bearing bush and the outer face of the bearing journal. The pressure disk serves as a supporting face for the second planar end face of the rolling-contact members. Since the dimensions determining the distance between the running face of the stop ring and the supporting face of the pressure disk include tolerances, it is not guaranteed that the rolling-contact members are guided in a play-free manner in the axial direction, parallel to the journal axis.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a bearing assembly which ensures that, in spite of the existence of tolerances, the rolling-contact members are guided sufficiently and securely.

In accordance with the invention, a bearing assembly for a bearing journal of a cross member of a universal joint has a bearing journal with a cylindrical outer face, an end face and a journal axis. A bearing element has a cylindrical bearing bore with a bottom face and a running face arranged at a radial distance from the outer face of the bearing journal. Rolling-contact members are cylindrical along at least part of their length. The ends of the rolling contact elements have at least partially planar first end face and second end face. The rolling contact members form a collar around the bearing journal between the running face and the outer face.

A stop ring is axially secured at the bearing journal or in the bearing bore. The stop ring has an annular contact face for the first end face of the rolling-contact members.

A pressure disk has a disk portion arranged between the end face of the bearing journal and the bottom face. Also, the pressure disk has a supporting portion which radially adjoins the disk portion with reference to the journal axis. The supporting portion is contacted by the second end faces of the rolling-contact members. The supporting portion is designed so as to be resilient.

The assembly in accordance with the invention achieves a kind of rim guidance for the rolling-contact members which continue to be aligned parallel to the journal axis. This prevents the rolling-contact members from jamming. During the to- and fro-movement, it is possible to achieve a rolling-contact movement of the rolling-contact members between the outer face of the bearing journal and the running face of the bearing bore. Due to the resilient arrangement, this kind of guidance can be maintained across a large tolerance range. In addition, a better load distribution and a longer service life is achieved. The supporting portion is designed so that, at least along the journal axis, it provides spring travel.

In order to achieve a sufficiently high supporting force, the supporting portion is formed integral with the disk portion. The supporting portion includes a reinforcing insert made of metal or plastics. Alternatively, the supporting portion may be in the form of a Belleville-spring-like metal ring connected to the disk portion. For example, the Belleville-spring may be partially embedded in the disk portion which can be produced from plastics. The material for the disk portion and for the parts of the supporting portions connected thereto is preferably a polyamide material (PA). The PA material may be reinforced by fibers for instance and into which it is possible to embed friction-reducing lubricant constituents, such as molybdenum disulphide. As a result, it is possible to reduce the friction between the bottom face of the bearing element and the end face of the bearing journal and also between the rolling-contact members and the supporting face of the supporting portion. The stop ring may also include a coating of the above-mentioned material.

The supporting face of the supporting portion is continuous and provides contact with the second end faces of the rolling-contact members. The supporting face can have a curved cross-section.

According to a further embodiment, in order to delimit the spring travel of the supporting portion, it may stop against the bottom face. This provides effective support in case the axial forces during operation or assembly are too high. By limiting the free space, it is possible, when pressing the bearing element in the form of a bearing bush, to limit the distances which can be covered by the supporting portion. Thus, latter cannot be impermissibly deformed. The deformation behavior and the spring properties can also be advantageously influenced by an embodiment which includes the reinforcing insert in the form of a disk. The circumference of the disk includes a plurality of slots. The slots form first and second sectors. The first sectors, in order to provide support, are bent relative to the second sectors. The second sectors include the supporting face for the second end faces of the rolling-contact members. The reinforcing insert can also be a metal disk. In this case, the supporting face is fully continuous.

In a preferred embodiment, at least one disk portion is made of plastics. Furthermore, it is possible for the bearing element to be formed by a yoke arm of a joint yoke of a universal joint. The bearing bore is worked directly into the yoke arm. The bearing element, in the form of an individual part, can also be connected to a flange. Thus, two such bearing units, together with the flange, provide a kind of yoke that receives the two bearing journals of a cross member that are arranged on one axis.

According to a further embodiment, the bearing element is formed by a bearing bush. The bearing bush is received in a bore of a yoke arm of a joint yoke of a universal joint.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1shows a drive shaft with two universal joints1at the ends of a plunging unit2. The individual parts are centered and arranged on the longitudinal axis X. The two universal joints may be identical, so that only one universal joint1needs to be described in detail. The universal joint1has a first joint yoke3and a second joint yoke4. The first joint yoke3is connected to a flange. The second joint yoke is connected to one end of the plunging unit2. If changes in angle occur between the two universal joints1at the ends of the plunging unit2, the latter enables a change in length between the articulation centers of the universal joints1.

The second joint joke4has a first yoke arm5and a second yoke arm6. The arms5and6are arranged at a distance from one another and are symmetrically positioned relative to the longitudinal axis X. The two yoke arms are identical with respect to receiving a cross member12which articulately connects them. Thus, the assembly will be described only with reference to one yoke arm, the first yoke arm5.

The first yoke arm5has a bore7accommodating a bearing bush that forms a bearing element8in the sense of the invention. However, it is also possible for the yoke arms themselves to form the bearing element. Thus, the bearing bore9in the bearing element8, in the form of a bearing bush, in connection with the bearing assembly according toFIG. 2, can directly be part of the first yoke arm5, it can replace the bore7.

Below, reference will be made to the description of the bearing assembly ofFIG. 2which shows a detail ofFIG. 1. The bearing bore9forms a cylindrical running face10. Furthermore, the bearing element8, in the form of the bearing bush, is closed at one end by a bottom face11. The bearing element8accommodates a bearing journal13. The bearing journal13, with reference to the journal axis15, has a circular-cylindrical outer face14. The bearing journal13also includes an end face16which extends at a right angle relative to the outer face14.

Rolling contact members17are provided in the annular gap between the running face10and the outer face14. The rolling contact members17adjoin one another in a row around the bearing journal13and thus form a collar. At least along a considerable part of their length, the rolling contact members17are cylindrical. Thus, the rolling contact members17are held between the outer face14and the running face10to carry out a rolling-contact movement. The rolling contact members17, towards their open ends, each include a first end face18and towards the bottom face11, they include a second end face19.

A stop ring20is positioned in the region of the open end of the bearing element8. The stop ring20is positioned in the bearing bore9. The stop ring20includes a contact face21for the first end face18of the rolling-contact members17. As illustrated, the stop ring20can form part of a seal and can be firmly arranged relative to the bearing element8in the axial direction. The stop ring20can also be held on the bearing journal13.

A pressure disk22is positioned between the end face16of the bearing journal13and the bottom face11of the bearing element8. The pressure disk22will be described in more detail in connection with the remaining Figures.FIG. 2shows a first embodiment of the pressure disk.

The pressure disk22guides the rolling-contact members17. The pressure disk22has a disk portion23that is made of plastic and is arranged between the end face16of the bearing journal13and the bottom face11. The bottom face11of the bearing element8has a recessed area that extends thereabout adjacent to the running face10. The disk portion23holds and centers the cross member with the bearing journal13in the direction of the journal axis15. The disk portion23is followed, in the radial direction with reference to the journal axis15of the bearing journal13, by a supporting portion24. The supporting portion24is integral with the disk portion23. The supporting portion24extends towards the bottom face11away from the journal axis15. The distance between the bottom face11and journal axis15continuously increases.

The supporting portion24includes a supporting face26with a curved cross-section. The supporting face26rests against the second end face19of the rolling members17and guides the same. The supporting portion24with the supporting face26is designed so that it provides a spring travel along the journal axis15. Thus, the supporting portion24is able to offset any tolerances which cause variations in length of the rolling-contact members17in the longitudinal direction. In this way, contact and guidance of the rolling-contact members17is always ensured because the contact face21contacts the first end faces18and the supporting face26contacts the second end faces19of all rolling-contact members17. The rolling-contact members17are thus held under a certain amount of axial pretension. Thus, the rolling contact members17are guided in a play-free manner. This ensures perfect rolling-contact conditions. Thus, a kind of rim guidance is provided for the rolling-contact members17which are also maintained if tolerance deviations occur. However, the spring travel of the supporting portion24is delimited by the supporting portion24abutting the bottom face11of the bearing element8.

According toFIG. 2, the pressure disk22is provided as an integral design. The disk portion23and the supporting portion24are one and the same material.

In the pressure disk embodiment according toFIG. 3, the functions are divided. Reference numbers are used which apply to parts identical to those shown inFIG. 2. In the case of those parts which are only similar or have a similar effect, the reference numbers have been increased by the value 100. The deviations of the embodiment according toFIG. 3relative to those ofFIG. 2will be described in greater detail below.

In the pressure disk122, the disk portion123is made of plastic. A partially embedded saucer-spring-like (Belleville-spring-like) supporting portion124is formed into the disk portion123. The free end on the supporting portion rests against the second end face19of the rolling-contact member17. The saucer-spring-like supporting portion24enables higher forces to be generated if it is formed of a saucer spring made of metal.

In the embodiment according toFIG. 4, those parts identical toFIGS. 1 to 3have been given the same reference numbers, with the reference numbers of any deviating parts having been increased by the value 100 as compared toFIGS. 1 to 3.

A pressure disk222includes a disk portion223. The disk portion223continues into the supporting portion224. A plate-spring-like reinforcing insert225is embedded in the supporting portion224and extends into the disk portion223. The reinforcing insert225, whose distance from the journal axis15is smaller, is positioned close to the bottom face211. Thus, this position ensures good supporting conditions if, parallel to the journal axis, forces are applied to the curved supporting face226of the supporting portion224.

In the embodiment according toFIG. 5, any components which are identical to those shown inFIGS. 1 and 2have been given the same reference numbers. The deviating design of the pressure disk and of the bearing element is indicated by the fact that their reference numbers have been increased by the value 300 as compared to the respective parts inFIGS. 1 to 3.

The bearing element308is in the form of a bearing bush. The bearing bush has an indentation in the form of a groove in the region between the bottom face311and the running face. The groove avoids notch effects and simplifies machining of the bottom face11and of the running face. The pressure face322has a disk portion323made of plastic. The disk portion323is followed by a supporting portion324which extends radially away from the journal axis15. The supporting portion324is formed integral with the disk portion323made of plastic. However, the supporting portion324is reinforced by a reinforcing insert.

The reinforcing insert includes a disk-like portion. The disk like portion extends into the disk portion323. The portion projecting radially from the disk portion323is divided into segments. The metallic reinforcing insert325is slotted on its circumference. Circumferentially distributed first sectors27are produced and angle towards the bottom face311, which they are supported on. Second sectors28are arranged between each two first sectors27. The second sectors28are angled away from the bottom face311. The second sectors28are embedded in the plastic supporting portion324. In order to contact the second end faces19of the rolling-contact members17, the second sectors28include a continuous supporting face326. The supporting face326has a curved cross-section.

In the embodiment according toFIG. 6, again any components which are identical to those in the embodiments according toFIGS. 1 to 3have been given the same reference numbers. The deviating components have been given reference numbers whose value has been increased by 400 relative the corresponding parts in the embodiments toFIGS. 1 and 2.

The bearing element includes a bearing bore with a curvature in the region of abutment between the running face and the bottom face411. The pressure disk422includes a plastic disk portion423between the bottom face411and the end face16. In the radial direction with reference to the journal axis15, the disk portion423is first followed by a thinned portion. The disk portion423is thinned in a direction parallel to the journal axis15.

The disk portion423changes into a thickened supporting portion424. The supporting portion424includes the supporting face426with the curved cross-section. The supporting portion424and the disk portion423are one piece. In addition, dashed lines indicate the normal position, the untensioned condition. The continuous line shows the contour of the supporting portion424in the built-in condition after assembly.

The spring travel of the supporting portion424that extends parallel to the journal axis15is delimited by the face of the supporting portion424facing away from the supporting face426which comes to rest against the bottom face411. Accordingly, the region between the supporting portion424and the disk portion423, which provides the spring characteristics, is prevented from being overloaded when the bearing element408is slid on to the bearing journal13. The spring characteristics of the supporting portion can be changed by reinforcing layers out of a glass fiber or carbon fiber material. The fibers may be embedded in the base material of the pressure disk422. It is also possible to add a percentage of fiber.

InFIG. 7, which has been modified relative toFIG. 2, the supporting portion24can be associated with a ring29. The ring29supports the permanently elastic springiness of the pressure disk22.