DE102008056024A1 - Bearing arrangement for bearing worm shaft of steering gear of vehicle, has bearings arranged relative to housing by element such that deflection of bearings in radial and axial directions is possible against spring force of element - Google Patents

Abstract

The arrangement (1) has bearings (5, 6) e.g. groove ball bearings and angular ball bearings, arranged relative to a housing (8) by a sleeve-like element (7) such that deflection of the bearings in a radial direction (r1) and in an axial direction (a) is possible against spring force of the element. The arrangement is mounted such that axial pre-tension in the bearings is present in a load-free condition of a shaft i.e. worm shaft (2), of a worm gear of a steering gear of a vehicle. An air gap is formed between a contact surface and an outer ring (14) in the load-free condition. The sleeve-like element is made of elastomer.

Description

The The invention relates to a bearing arrangement for supporting a shaft in a first bearing and in an axial direction from the first bearing spaced second bearing with one bearing.

bearing assemblies This type are used especially in steering gears. These Most have a worm gear to the steering movements of the steering wheel forward to the wheels. The worm gear is subject Wear, which must not cause the Steering gets over time as game gets. Therefore, the storage the worm on a shaft so accomplished that a depository is made adjustable in angle. This is one of the Bearing of the worm shaft with an elastic element (spring element) provided that can generate a radially acting force, so that the worm or the worm shaft always on the worm wheel of the worm gear is pressed. This way will Wear in the worm gear balanced.

Such a solution is in the DE 100 51 306 A1 described. Here, a coil spring acts in the region of a bearing, with which a pinion is mounted, which meshes with a mating gear to hold a steering gear backlash.

The EP 1 106 474 B1 shows an electric power steering, in which a drive shaft is held by means of deflection radially deflectable, wherein the deflection means are designed as an elastic member to engage the driving wheel of the steering device without play in the driven wheel.

In the US Pat. No. 6,435,050 B1 A similar solution is disclosed, here a ring of elastomeric material is used to obtain said radial elasticity of the worm shaft of a worm gear. Such an embodiment is also in the DE 101 22 434 A1 to see.

A spring used in the area of the bearing is also from the WO 2006/051034 A1 known to achieve the desired radial spring effect.

all Previously known solutions mean that the worm shaft mounted on one side in a fixed bearing both radially and axially fixed while the other bearing is designed as a floating bearing is that the said radial, elastic movement possibility offers. The fixed bearing is, however, kept adjustable in angle. By the achieved radial spring effect on the floating bearing side is wear-related game eliminated.

This has a disadvantageous consequence that the connection of the shaft designed relatively complex on a drive unit at the location of the fixed bearing must become. Often a four-point bearing is used here, which requires the installation of relatively many parts. Also to achieve the radial spring effect is a relatively high production engineering Effort driven. Set the required spring elements not only expensive additional components, but also the assembly effort is high, in particular to assemble the so equipped steering gear. Accordingly, the previously known solutions relatively expensive and expensive.

Of the Invention is therefore the object of a bearing assembly of the type mentioned above, in which reliable Way the required radial spring effect is achieved to to ensure a backlash-free gear arrangement in which this however, in a simpler, more reliable and cheaper way Way can be achieved. Furthermore, an axial compliance is also aimed at their connection to movements of the worm shaft To make a drive unit simple and inexpensive.

The Solution of this problem by the invention is characterized in that that both bearings of the bearing assembly by means of elastic means are arranged relative to a housing that against the Spring force of the elastic means a deflection of the two bearings in the radial direction and in the axial direction is possible. It is preferably provided that the bearing assembly mounted so is that in the load-free state of the shaft axial preload present in the two camps.

These axial preload can be oriented so that they are the two Bearing pushes towards each other in the axial direction.

The Both bearings are advantageous as deep groove ball bearings or angular contact ball bearings executed. The two bearings are preferably in X-arrangement arranged.

The Shaft is preferably the worm shaft of a worm gear. The worm gear is preferably part of a steering gear of a Vehicle.

At least one axial abutment surface for the outer ring of one of the bearings for the direct or indirect abutment of the outer ring can be arranged on the housing or on a component fastened to this, in order to limit the axial mobility of the floating shaft in this way. It is preferably provided that on the housing or on a component attached to this two axial contact surfaces for the outer rings of both bearings are arranged, that is, said axial displaceability is limited in both axial directions. In the load-free state of the shaft may be present between the at least one contact surface and the outer ring, an air gap. This preferably has a width between 0.05 mm and 3 mm; Particularly preferred is an air gap between 2 and 5 tenths of a millimeter.

The Both bearings and the two elastic means can to a plane on which the axial direction of the bearing assembly perpendicular is, be formed symmetrically.

The Shaft can have a flexible coupling with a drive unit be connected, wherein the elastic coupling between a drive shaft the drive unit and the shaft an angular offset, an axial Offset and a radial offset allows.

A Further development provides that the elastic means as a sleeve-shaped Element are formed, wherein the sleeve-shaped Element at least over part of its circumference in radial section at least quarter-circular section having.

Prefers at least over the sleeve-shaped element a part of its circumference in radial section a U-shaped trained section on. It can also be provided that the sleeve-shaped element at least over a portion of its circumference in radial section a double U-shaped Section has.

there the sleeve-shaped element preferably over its entire scope the mentioned section.

Therefore is therefore intended that as a spring element for generating a radial Biasing force a sleeve-shaped element is used, in the radial section, at least over a quarter circle extending arch, which has the desired elasticity produced, with which the bearing held in position, however radial and is axially deflectable.

A Bore in the housing for receiving the sleeve-shaped Elements can be radially offset to the theoretical axis of the shaft be introduced, wherein the sleeve-shaped element then formed rotationally symmetrical. This offset (eccentricity) causes a radial force in the spring sleeve, whereby the Bearings and thus the worm shaft pressed against the worm wheel becomes. Wear-related play is thereby prevented.

alternative can also be provided that the housing bore for Recording the sleeve-shaped element concentric is introduced to the theoretical axis of the shaft, wherein the sleeve-shaped element a radially offset receiving area for has the bearing.

The sleeve-shaped element is preferably made of spring steel. It can be made by a deep drawing process. In the sleeve-shaped Element can have recesses (eg long holes) be introduced to influence the radial spring stiffness.

Around an improved damping behavior of the sleeve-shaped Elements to achieve, provides a further development that the sleeve-shaped Element is provided with an elastomer or rubber material. The Elastomer or rubber material can be introduced into the area be formed by the at least quarter-circular Section is limited.

The sleeve-shaped element may further have a radially outer Attachment section, with play or transition fit sits in the bore of the housing. It can also be a radial having inner receiving portion for the bearing, wherein between the receiving section and the outer ring of the bearing transitional or press fit.

A special embodiment provides that the sleeve-shaped Element in two mutually perpendicular radial directions having different radial spring stiffnesses. Ie. if required, the spring characteristic of the spring sleeve in the preferred spring direction are made less stiff, than in a direction rotated by 90 °. This will be the storage transverse to the preferred direction (intended direction of Spring force) stiffer, in which no radial deflection is needed becomes. This can be achieved by a non-rotationally symmetric Configuration of the parameters that the spring stiffness of the sleeve determine.

The sleeve-shaped element is subjected to its production by deep drawing a known heat treatment. The spring characteristic of the sleeve-shaped element is designed by the choice of the geometry of the element so that the spring sleeve presses with sufficient force the worm shaft over the entire life and thus over the entire expected wear to the worm wheel. The spring characteristic of the spring sleeve is determined by the geometry (sheet thickness, curvature of the sheet in radial section with quadrant, U-shape, double U-shape, possibly long holes in the sheet) so that the spring force changes only slightly in the expected Anstellbereich, This means that the curve is as flat as possible in the working environment desired area. To achieve increased damping, the spring sleeve can be sprayed as mentioned with a rubber compound. The sleeve is inserted with a slight transition fit or clearance in the housing, which facilitates their assembly; the bearing outer ring receives a transitional or interference fit to prevent it from falling apart during transport or during assembly.

While the use in steering gears the preferred application for the invention is, it can as well as in other axial and radial spring bearings are used.

The The invention thus provides centrally that both bearing points of the shaft as resilient in both radial and axial directions Bearings are trained. The wave is therefore stored virtually floating. So not only wear-related bearing changes It will also be intercepted and freedom of play ensured given a certain elasticity in the axial direction of the shaft. The shaft is accordingly placed in two floating bearings stored, however, are axially braced against each other.

Come Deep groove ball bearings for the two bearings used, the bearing clearance of the two bearings is chosen so that an operating pressure angle of about 25 ° on average. The bearing arrangement preferably forms a spring-loaded Storage with two bearings in X arrangement. Thus, each bearing axial forces, resulting from the steering movement, record in one direction. The radial stiffness of the elastic means is chosen so that the wear compensation between worm shaft and worm wheel over the entire operating life is, d. H. There must always be so much radial contact pressure be that the worm shaft can be tracked, to ensure play-free operation.

The However, axial rigidity of the bearing is chosen so that taking into account all tolerances of the shaft and the Housing always positive bias of the two bearings is ensured (designed the bias is preferably on about 3% of the load capacity of the bearing, which is a bias range between 1% and 6% of the load capacity of the bearing has proven successful). On the other hand, the axial stiffness of the elastic means be chosen so that from the axial forces resulting axial displacements of the worm shaft still in one area lie, by the elastic coupling over which the Worm shaft with a drive unit communicates balanced can be. The axial displaceability of the bearing can be limited meanwhile, by the described contact surface for the bearing outer ring.

With the formation of the elastic means in the explained Art is also in a cost effective way with a storage radial suspension created over a long service life maintains the desired spring characteristic.

There the number of required components is less than previously known solutions, the bearing assembly can be cheaper will be realized. In particular, can waive four-point camp become.

In the drawing embodiments of the invention are illustrated. Show it:

1 FIG. 2 schematically shows the radial section through a bearing arrangement for the worm of a worm gear according to a preferred embodiment of the invention, FIG.

2 in the illustration according to 1 an alternative embodiment of the invention,

3 the schematic representation of one of the bearing points of the bearing assembly according to 1 respectively. 2 in an alternative embodiment of the invention,

4 the schematic representation of one of the bearing points of the bearing assembly according to 1 respectively. 2 in a further alternative embodiment of the invention,

5 the schematic representation of one of the bearing points of the bearing assembly according to 1 respectively. 2 in a further alternative embodiment of the invention,

6 the schematic representation of one of the bearing points of the bearing assembly according to 1 respectively. 2 in a further alternative embodiment of the invention and

7 the elastic means including bearings according to the embodiment according to 1 respectively. 2 , seen in the axial direction.

In 1 is a bearing arrangement 1 to see that is needed for a steering gear, which uses a worm gear to deflect the steering movements. From the worm gear is a wave 2 in the form of a worm shaft and a worm wheel 15 indicated.

The worm shaft 2 is stored in two storage locations, namely in a first storage location 3 and in a second depository 4 , The two bearings 3 . 4 are spaced apart in the axial direction a. Every depository 3 . 4 each has a warehouse 5 and 6 on, in the embodiment as Rillenku is executed gel camp.

It is essential that both bearings 3 and 4 Both in the radial direction r and in the axial direction a are formed elastically. The radial and axial elasticity is in each case by a sleeve-shaped element 7 made, which represent elastic means. This will radial and axial elasticity of the shaft 2 at both bearings 3 . 4 relative to a housing 8th produced.

As in 1 can be seen, is the largely rotationally symmetric, sleeve-shaped element 7 designed to make it a section 9 ' has, which has a U-shape in the radial section. The U-shaped structure is once through a radially outer receiving portion 12 limited, with a press fit in a hole 10 of the housing 8th sitting. On the other hand, the U-shaped structure by a radially inner receiving portion 13 limited, the outer ring with clearance fit 14 of the camp 6 wearing.

In 1 is an offset x marked, which is the displacement of the worm shaft 2 indicates from the theoretical center (offset housing bore to the worm shaft). This offset causes the worm shaft 2 due to the two sleeve-shaped elements 7 elastically biased and against the worm wheel 15 pressed, so that wear-related game can be compensated.

With rotationally symmetrical design of the sleeve-shaped element 7 are the radial spring constant of the element in two mutually perpendicular direction r ₁ and r _{2 the} same. This must, as mentioned above, but not necessarily be the case.

The axial displaceability of the bearings is in the solution according to 1 only by the deformability of the elastic means 7 limited. In the solution according to 2 this is not the case: here is the case 8th a component attached to the bearing outer rings 14 the two camps 5 . 6 a contact surface 17 forms. Consequently, the axial displaceability of the shaft is important 2 A limitation in both directions. The contact surface 17 may be provided with an insulating layer, for example with a rubber layer, which has the advantage that it can be damped the stop sounds of the bearing outer ring on the contact surface.

In the load-free state of the shaft 2 the entire assembly is biased in the axial direction; There is also radial preload, so that the worm shaft 2 with a certain preload force on the worm wheel 15 is applied.

In the load-free state remains in the solution according to 2 an air gap s between the contact surface 17 and the bearing outer ring 14 in front.

More specifically, the air gap s is located between the contact surface 17 and the end face of a radially extending portion of the sleeve-shaped element 7 before, this section the bearing outer ring 14 embraces.

This Slit s (stop play) is chosen so that under consideration the tolerance chain of the components involved always ensured is that maintain an axial bias in the assembly becomes.

The air gap s corresponds to the unilateral stop play; the whole game of the wave 2 in the axial direction is accordingly 2 × s.

The two solutions according to the 1 and 2 are mirror symmetric to a midplane 18 executed, on which the axial direction a is vertical.

As can be further seen, the wave is 2 , ie the worm shaft of the worm gear, via a flexible coupling 19 (Torsion coupling) with a drive shaft 21 a drive unit 20 connected. The elastic coupling 19 equals angular error as well as axial and radial offset between the shafts 2 and 21 out.

The two camps 5 . 6 are in this case the same size; but this is not mandatory.

The sleeve-shaped element 7 can by means of indicated screw on the housing 8th be set. If necessary, a suitable washer may be provided to achieve an improved distribution of the pressure of the screws. Other mounting options are of course possible.

Alternative embodiments of the sleeve-shaped element 7 are in the 3 to 6 to see.

3 shows a "minimal solution" in which the sleeve-shaped element 7 in radial section, a quarter-circle-shaped designed section 9 having. To increase the damping capacity is here still provided that of the section 9 limited area at least partially with elastomer or rubber material 11 is filled, which can be accomplished by injection molding the mass production technology easy. The radial spring constant of the sleeve-shaped element 7 is higher than the solution according to 1 respectively. 2 ,

In 4 has the sleeve-shaped element 7 a double U-shaped designed section 9 '' on. The radial spring constant of the sleeve-shaped element 7 is thereby lower than in the solution according to 1 respectively. 2 ,

The solution according to 5 differs from the one according to 1 respectively. 2 only in that in the "receiving space" of the U-shaped configuration of the sleeve-shaped element 7 elastomeric material 11 was injected.

Similar to the solution according to the 4 is also according to those 6 provided that the sleeve-shaped element 7 having a multiple U-shaped contour. In the solution according to 6 a total of three U-shaped sections 9 ' together.

As already explained above, it can also be provided that in the sleeve-shaped element 7 Recesses are introduced to influence the radial spring stiffness. Such a solution shows 7 , Here is the sleeve-shaped element 7 - Viewed in the axial direction a - to see, with two recesses 16 are provided in the form of slots to the radial spring stiffness of the sleeve-shaped element 7 in a radial direction. It can also be seen that although this is symmetrical but not rotationally symmetrical, but that here a preferred direction results, which has a lower spring stiffness than a direction which is perpendicular thereto.

Characterized in that the U-shaped formations of the sleeve-shaped elements 7 axially outside the extension of the bearing rings of the bearings 6 . 7 are sufficient radial and axial deformability of the elements 7 reached.

1

bearing arrangement

2

wave (Worm shaft)

3

first depository

4

second depository

5

camp

6

camp

7

elastic Medium (sleeve-shaped element)

8th

casing

9

at least quarter-circular portion of the sleeve-shaped Elements

9 '

U-shaped formed portion of the sleeve-shaped element

9 ''

double U-shaped section of the sleeve-shaped Elements

10

drilling

11

elastomer or rubber material

12

radially outer attachment section

13

radial inner receiving section

14

outer ring

15

worm

16

recess (Long hole)

17

contact surface

18

level (Plane of symmetry)

19

elastic clutch

20

drive unit

21

drive shaft

a

axial direction

r

radial direction

r ₁

first radial direction

r ₂

second radial direction

x

offset the housing bore / offset of the housing

s

air gap

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 10051306 A1 [0003]
• - EP 1106474 B1 [0004]
• - US 6435050 B1 [0005]
• - DE 10122434 A1 [0005]
• WO 2006/051034 A1 [0006]

Claims (27)

Bearing arrangement ( 1 ) for supporting a shaft ( 2 ) in a first depository ( 3 ) and in an axial (a) from the first bearing ( 3 ) spaced second storage location ( 4 ) each with a bearing ( 5 . 6 ), characterized in that both bearings ( 5 . 6 ) by means of elastic means ( 7 ) relative to a housing ( 8th ) are arranged so that against the spring force of the elastic means ( 7 ) a deflection of the two bearings ( 5 . 6 ) in the radial direction (r) and in the axial direction (a) is possible. Bearing arrangement according to claim 1, characterized in that it is mounted so that in the load-free state of the shaft ( 2 ) an axial preload in the two bearings ( 5 . 6 ) is present. Bearing arrangement according to claim 2, characterized in that the axial preload the two bearings ( 5 . 6 ) in the axial direction (a) pushes each other. Bearing arrangement according to one of claims 1 to 3, characterized in that the two bearings ( 5 . 6 ) Are deep groove ball bearings or angular contact ball bearings. Bearing arrangement according to claim 4, characterized in that the two bearings ( 5 . 6 ) are arranged in an X-arrangement. Bearing arrangement according to one of claims 1 to 5, characterized in that the shaft ( 2 ) is the worm shaft of a worm gear. Bearing arrangement according to Claim 6, characterized that the worm gear is part of a steering gear of a Vehicle is. Bearing arrangement according to one of claims 1 to 7, characterized in that the housing ( 8th ) or on a component fastened to this at least one axial contact surface ( 17 ) for the outer ring ( 14 ) one of the bearings ( 5 . 6 ) for the direct or indirect installation of the outer ring ( 14 ) is arranged. Bearing arrangement according to claim 8, characterized in that on the housing ( 8th ) or on a component attached to this two axial abutment surfaces ( 17 ) for the outer rings ( 14 ) of both camps ( 5 . 6 ) are arranged. Bearing arrangement according to claim 8 or 9, characterized in that in the load-free state of the shaft ( 2 ) between the at least one contact surface ( 17 ) and the outer ring ( 14 ) An air gap (s) is present. Bearing arrangement according to claim 10, characterized the air gap (s) has a width between 0.05 mm and 3 mm. Bearing arrangement according to one of claims 1 to 11, characterized in that the two bearings ( 5 . 6 ) and the two elastic means ( 7 ) to a level ( 18 ), on which the axial direction (a) of the bearing arrangement ( 1 ) is perpendicular, are formed symmetrically. Bearing arrangement according to one of claims 1 to 12, characterized in that the shaft ( 2 ) via an elastic coupling ( 19 ) with a drive unit ( 20 ), wherein the elastic coupling ( 19 ) between a drive shaft ( 21 ) of the drive unit ( 20 ) and the wave ( 2 ) allows angular misalignment, axial misalignment, and radial misalignment. Bearing arrangement according to one of claims 1 to 13, characterized in that the elastic means ( 7 ) are formed as a sleeve-shaped element, wherein the sleeve-shaped element at least over a part of its circumference in a radial section at least quarter-circular section ( 9 ) having. Bearing arrangement according to claim 14, characterized in that the sleeve-shaped element ( 7 ) at least over part of its circumference in radial section a U-shaped section ( 9 ' ) having. Bearing arrangement according to claim 14, characterized in that the sleeve-shaped element ( 7 ) at least over part of its circumference in the radial section a double U-shaped section ( 9 '' ) having. Bearing arrangement according to one of claims 14 to 16, characterized in that the sleeve-shaped element over its entire circumference the portion ( 9 . 9 ' . 9 '' ) having. Bearing arrangement according to one of claims 14 to 17, characterized in that a bore ( 10 ) in the housing ( 8th ) for receiving the sleeve-shaped element ( 7 ) radially offset to the theoretical axis of the shaft ( 2 ), wherein the sleeve-shaped element ( 7 ) is rotationally symmetrical. Bearing arrangement according to one of claims 14 to 17, characterized in that a bore ( 10 ) in the housing ( 8th ) for receiving the sleeve-shaped element ( 7 ) concentric with the theoretical axis of the shaft ( 2 ), wherein the sleeve-shaped element ( 7 ) has a radially offset receiving area for the bearing ( 6 ) having. Bearing arrangement according to one of claims 14 to 19, characterized in that the sleeve-shaped element ( 7 ) consists of spring steel. Bearing arrangement according to claim 20, characterized in that the sleeve-shaped element ( 7 ) is produced by a deep drawing process. Bearing arrangement according to one of claims 14 to 21, characterized in that in the sleeve-shaped element ( 7 ) Recesses ( 16 ) are introduced to influence the radial spring stiffness. Bearing arrangement according to one of claims 14 to 22, characterized in that the sleeve-shaped element ( 7 ) with an elastomer or rubber material ( 11 ) is provided. Bearing arrangement according to claim 23, characterized in that the elastomer or rubber material ( 11 ) is introduced into the region which passes through the at least quarter-circular section (FIG. 9 . 9 ' . 9 '' ) is limited. Bearing arrangement according to one of claims 14 to 24, characterized in that the sleeve-shaped element ( 7 ) a radially outer mounting portion ( 12 ) with play or transition fit in the bore ( 10 ) of the housing ( 8th ) sits. Bearing arrangement according to one of claims 14 to 25, characterized in that the sleeve-shaped element ( 7 ) a radially inner receiving portion ( 13 ) for the warehouse ( 5 . 6 ), wherein between the receiving portion ( 13 ) and the outer ring ( 14 ) of the warehouse ( 6 ) Transition or interference fit is present. Bearing arrangement according to one of claims 14 to 26, characterized in that the sleeve-shaped element ( 7 ) in two mutually perpendicular radial directions (r ₁ , r ₂ ) has different radial spring stiffnesses.