DE102010056007A1 - Biasing device of servo unit used in steering system of motor vehicle, has spring clip provided with two legs between which spring damping element is arranged - Google Patents

Abstract

The biasing device has a biasing main structure has a spring clip with two legs between which a spring damping element is arranged. The biasing main structure is arranged parallel to the engine shaft. A floating bearing is provided between engine shaft and biasing main structure. Independent claims are included for the following: (1) servo unit; and (2) steering system.

Description

The invention relates to a biasing device for a shaft bearing, as it finds in particular in a servo unit application, by means of which a drive torque of an electric motor can be brought into action in a steering system to assist a driver of a motor vehicle when driving.

Such a device is inter alia from the EP 1 866 195 B1 known. This discloses a steering system for a motor vehicle with a worm wheel engaging in a worm, wherein the worm has a movable bearing at one end and the non-locating bearing can be clamped in a bearing bush by a spring which engages around the bearing bush. The bearing bush has an opening for the contact of the spring with the floating bearing. With this arrangement, disturbing noises are to be reduced and at the same time an adjustment of the floating bearing to compensate for the wear is to be made possible. The bushing has an opening through which a hydraulic or mechanical spring / damper mechanism, not shown, can press against the floating bearing.

Also DE 10 2007 047 369 A1 relates to a steering system for a motor vehicle. The steering system comprises a worm gear with a worm shaft, a worm wheel, a gear housing and a movable in the direction of the worm shaft thrust piece, which exerts force on the worm in the direction of the worm wheel. In this case, the worm shaft at a first end a fixed bearing and at a second end to a movable bearing, wherein the fixed bearing is to allow a pivotal movement of the worm shaft relative to the worm wheel to allow compensation of wear and counteract noise.

The present invention is based on the object to improve a biasing device of the type mentioned in terms of mountability and the acoustic properties.

This object is achieved with a biasing device with the features mentioned in claim 1, which is preferably integrated in a skirt of a shaft bearing of a servo unit according to claim 6. In addition, a steering system with this servo unit according to claim 8 and a motor vehicle with this steering system according to claim 10 are provided.

The biasing device according to the invention comprises a band-shaped, elastically deformable and self-damping properties exhibiting spring-damping element for acting on a bearing mounted in a bearing bush bearing with a spring force.

Thus, a biasing device is provided, which is advantageous to manufacture easily and inexpensively, since it has few items. In addition, the biasing device according to the invention requires very little space, which considerably simplifies consideration in the design and assembly.

In a preferred embodiment of the biasing device according to the invention it is provided that the biasing means comprises a spring clip with two legs, wherein the spring-damping element is disposed between the legs of the spring clip.

With the use of the spring clip, a relatively linear spring characteristic is advantageously achievable in comparison to other spring types, and so a consistent spring force can be brought into effect.

The combination of the spring clip with the spring-damping element dampens vibrations advantageous, whereby oscillating masses are braked. This has a positive effect on the acoustic behavior. In addition, with the use of the spring-damping element, a progressive course of the spring characteristic can be achieved, which uses depending on the height of the spring-damping element used in a compression of the legs of the spring clip.

In a preferred embodiment of the biasing device according to the invention it is provided that the spring clip is already biased to each other in a parallel position of the two legs.

This can advantageously be brought into effect in flat installation situations, a bias.

In a further preferred embodiment of the biasing device according to the invention it is provided that the spring-damping element is formed from at least one elastomer.

Elastomers have advantageous material properties in order to achieve mechanical and acoustic damping. The use of multiple elastomers in layers allows a combination of different damping properties.

In a further preferred embodiment of the biasing device according to the invention it is provided that the spring-damping element has a lower height than a distance height between the two legs of the spring clip in a parallel position.

This is advantageous to realize a spring characteristic of the biasing device, which increases progressively towards the end of the spring travel. The spring loaded parts abut against an end stop of the pretensioner at a significantly reduced speed, which in turn leads to acoustic improvements.

The biasing device according to the invention is preferably integrated in all the above embodiments in a servo unit with at least one motor and a motor shaft having a gear stage. The motor shaft is rotatably mounted in a fixed bearing and a movable bearing and driven by the motor. Because the floating bearing is mounted resiliently in the bearing bush and the bearing is angularly adjustable, the motor shaft with the fixed bearing is pivotable as a fulcrum between an upper lifting point and a lower lifting point. The biasing device according to the invention is arranged in the bearing bush on an outer bearing ring of the movable bearing and brings on the floating bearing on a bias.

This makes it possible advantageously to achieve optimum efficiency in a power transmission between the motor shaft and the wheel, since component and assembly tolerances and wear can be compensated, the gear stage with the motor shaft as a worm shaft and the wheel as a worm wheel can be operated at the optimal pitch become.

In addition, with the servo unit according to the invention, audible abnormalities can be suppressed, in particular even when the direction of rotation of the wheel changes. Furthermore, a torque can be transmitted with the least possible fluctuations.

Furthermore, the servo unit according to the invention provides a simple and inexpensive construction, since the engine components are integrated directly into the housing of the servo unit and the motor shaft is directly part of the gear stage. This advantageously saves additional items.

Preferably, it is provided that the upper stop point is reached when the biasing device is brought to block and the motor shaft of the servo unit is aligned in the upper lifting point centric to the motor.

As a result, it is advantageously possible to optimally place the motor shaft and to operate in this optimum position in a large part of the operation.

The servo unit according to the invention is preferably integrated in all the above embodiments in a steering system with a steering column, steering linkage and the steering column and the steering linkage interconnecting steering gear. The wheel of the servo unit is in operative connection with a steering spindle.

The aforementioned advantages of the servo unit according to the invention as an assembly thus benefit the steering system with the servo unit as a component.

In a further preferred embodiment of the steering system according to the invention, the servo unit is integrated in the steering column.

The steering system thus advantageously has a relatively small space requirement and can be advantageously installed preassembled with the servo unit.

The steering system according to the invention is preferably arranged in a motor vehicle. The aforementioned advantages of the servo unit according to the invention as an assembly thus benefit the steering system or the motor vehicle with the servo unit as a component.

Further preferred embodiments of the invention will become apparent from the remaining, mentioned in the dependent claims characteristics.

The invention will be explained below in embodiments with reference to the accompanying drawings. Show it:

1 an inventive steering system:

2 a servo unit according to the invention:

3 a detailed view of the servo unit according to the invention:

4 a biasing device according to the invention and

5 a view of a bearing bush of the servo unit according to the invention.

In 1 is exemplary and not limiting an inventive steering system 40 shown. The steering system has a steering column 46 and steering linkage 50 on. The steering column 46 and the steering linkage 50 are about a steering gear 42 connected with each other. The steering column 46 includes a steering shaft 48 , a servo unit 10 and a propeller shaft 44 , The PTO shaft 44 opens at a lower end of the steering column 46 in the steering gear 42 and the steering spindle 48 is at an upper end of the steering column 46 arranged to receive a steering wheel, not shown.

The steering column 46 serves to the steering wheel of a motor vehicle with the steering gear 42 connect to. The steering gear 42 converts the rotational movements, which generates a driver of the motor vehicle by turning the steering wheel, in translational movements, via the steering linkage 50 are transmitted to not shown front wheels of the motor vehicle.

The servo unit 10 in this case exercises the function of a steering assistance. A drive torque generated by it reduces a force required by the driver to turn the steering wheel. The servo unit 10 is also used in driver assistance functions of the motor vehicle, in which an automatic intervention in the steering is to take place.

Shown is the servo unit according to the invention 10 by way of example and not by way of limitation 2 in a cutaway model. The components of the servo unit 10 are in a housing 26 houses. The servo unit 10 has a motor as drive 12 on. Preferably, the engine is 12 an electric motor with a rotor package 54 and a stature 56 , The motor 12 drives a motor shaft 14 at. This is the stature 56 rotationally fixed to the housing 26 arranged and the rotor package 54 is non-rotatable with the motor shaft 14 connected.

The motor shaft 14 is in a camp 18 and a floating warehouse 20 rotatably mounted. This is the fixed camp 18 preferably at a motor near end of the motor shaft 14 and the floating bearing 20 at the other end of the motor shaft, which is not close to the motor 14 arranged.

The motor shaft 12 is engaged with a wheel 16 , The wheel 16 and the motor shaft 14 have corresponding to each other corresponding force transmission elements. The axes of rotation of the motor shaft 14 and the wheel 16 lie on two substantially mutually perpendicular planes. The motor shaft 14 and the wheel 16 preferably form a Schraubradgetriebe, in particular a worm gear.

In 2 is a worm gear as a gear stage of the servo unit according to the invention 10 shown. The motor shaft 14 has a functional area in which the motor shaft 14 is designed as a worm shaft. The wheel 16 is accordingly designed as a worm wheel and the power transmission elements are formed by a worm toothing. The motor shaft 14 acts in the functional area on the wheel 16 ,

The axis of rotation of the wheel 16 is substantially parallel to the axis of rotation of the steering shaft 48 arranged or is the wheel 16 preferably directly on the steering spindle 48 attached. The steering spindle 48 in turn can be brought into operative connection with a steering wheel of a motor vehicle. If a driver of the motor vehicle turns on the steering wheel, this causes the steering spindle 48 turned. By a drive torque of the engine 12 this rotational movement is supported, the driver's effort is reduced accordingly.

The motor shaft 14 has a variable distance to the wheel 16 on. The motor shaft 14 is in a plane perpendicular to the axis of rotation of the wheel 16 pivotable. The change of the distance between the motor shaft 14 and the wheel 16 by pivoting the motor shaft 14 is between the fixed limits of an upper lifting point 36 and a lower attachment point 38 on the power transmission elements by a few tenths of a millimeter possible, preferably 0.1 to 0.5 mm. This is realized in the embodiment shown in that the floating bearing 20 in a bushing 28 is spring-mounted and the fixed bearing 18 is designed accordingly and allows an angular adjustment in this area. The fixed bearing is preferred 18 a pendulum roller bearing. The camp 18 is thus the pivot point for the pivoting of the motor shaft 14 ,

In the bearing bush 28 is a pretensioner 30 arranged, through which the motor shaft 14 permanently acted upon by a defined spring force. The bearing bush 28 Can be as a separate part or part of the case 26 the servo unit 10 be formed.

The upper lifting point 36 of the floating bearing 20 is through the biasing device 30 and defines their block length. If the pretensioner is compressed to block, the upper attachment point is 36 reached. In this case, the biasing device 30 acoustically damping properties in order to stop at the floating bearing 20 in the upper lifting point 36 to make no disturbing noises.

A counterforce against the spring force of the pretensioner 30 is due to the drive torque of the motor in interaction with the power transmission elements of the motor shaft 14 and the wheel 16 generated. With increasing drive torque of the motor 12 becomes the motor shaft 14 leveraged out of the gearing by a defined amount.

The lower lifting point 38 of the floating bearing 20 is by the wheel 16 Are defined. Poke those Gear teeth of the motor shaft 14 and the wheel 16 on top of each other, is the lower attachment point 38 reached.

By pivoting the motor shaft 14 between the upper and lower lifting points 36 and 38 , the pitch point of the teeth of the motor shaft shifts 14 and the wheel 16 , The servo unit according to the invention is preferred 10 designed so that the motor shaft 14 in the upper lifting point 36 centric to the engine 12 is aligned and therefore in an ideal location.

Is by the drive torque of the engine 12 no counterforce against the spring force of the biasing device 30 generated, the motor shaft is located 14 in a disengaged position, that is, the motor shaft 14 is slightly angled to the stator 56 arranged. Does the engine 12 a drive torque and lever the motor shaft 14 from the gearing, becomes the pretensioner 30 compressed and the motor shaft 14 shifts from the deachsierten position into the centric position, in which the biasing device 30 sitting on block. Preferably, this block state is reached from a force between 10 N and 30 N, in particular between 15 N and 25 N.

In 3 is a detailed view of the floating bearing 20 the servo unit according to the invention 10 shown. The floating bearing 20 is preferably a roller bearing and has an inner bearing ring 22 and an outer bearing ring 24 on. Between the inner bearing ring 22 and the outer bearing ring 24 Walzelemente or ball elements are arranged.

With the inner bearing ring 22 is the floating bearing 20 on the bike 16 engaged motor shaft 14 attached. The outer bearing ring 24 is in the bushing 28 sprung edged. In the bearing bush 28 is to the biasing device 30 integrated. The bearing bush 28 indicates the reception of the floating bearing 20 and the pretensioner 30 an inner contour approximately in the form of a long hole.

The pretensioner 30 includes a spring element 32 and a spring-damping element 34 , It exerts a relatively constant spring force over the floating bearing 20 on the motor shaft 14 to compensate for tolerances. The motor shaft 14 Thus, with a defined spring force in the plane normal to the axis of rotation of the wheel 16 against the wheel 16 pressed. The pretensioner 30 acts on the outer bearing ring 24 of the floating bearing 20 ,

An assembly of the pretensioner 30 can from an outside of the case 26 Made easy, since the biasing device 30 parallel to the motor shaft 14 between outer bearing ring 24 and bearing bush 28 is insertable. The housing 26 the servo unit 10 is in this area in functional condition by a sealing plug 52 locked.

In 4 is exemplary and not limiting, a biasing device according to the invention 30 in detail with the spring clip 32 and the spring-damping element 34 shown. The illustrated biasing device is in this case in a non-biased state.

The spring clip 32 has two legs made of flat material. Between the two legs is the spring-damping element 34 arranged. The spring-damping element 34 is made of an elastic material with good mechanical and acoustic damping properties, preferably formed from an elastomer. The spring-damping element 34 in this case has a height which is lower than a height which results when the two legs of the spring clip 32 parallel to each other.

The spring clip 32 and thus also the pretensioning device 30 are in a prestressed state when the legs of the spring clip 32 parallel to each other. In this preloaded condition, another force acts on the pretensioner 30 , so are the legs of the spring clip 32 initially further compressed without affecting the spring-damping element 34 thereby an additional force acts. In this first region of the spring travel of the biasing device 30 , ie in the region between mutually parallel legs and at an acute angle to each other standing legs before the spring-damping element 34 receives a substantial force, the biasing means 30 a relatively flat and straight spring characteristic. A force increase over the travel is very low (<5 N to 0.3 mm). This acts in this area of the spring travel on the movable bearing 20 a nearly constant spring force on the motor shaft 14 ,

A second portion of the spring travel of the biasing device 30 begins when the legs of the spring clip are at an acute angle to each other and the spring-damping element 34 simultaneously absorbs a significant force. This second region of the spring travel of the biasing device 30 has a progressive spring characteristic, since the spring characteristics of the spring clip 32 and the spring-damper element 34 overlay and the spring-damper element 34 has a progressive spring characteristic. The increase in force over the spring travel is in the second region of the spring travel of the biasing device 30 relatively large. The range of the spring travel of the biasing device 30 preferably starts immediately before the upper attachment point 36 ,

The upper lifting point 36 is at the end of the spring travel of the biasing device 30 achieved when the legs of the spring clip 32 and the spring-damping element positioned therebetween 34 not further squeezable.

The spring clip 32 can also be a leg spring, a V-spring, U-spring or the like according to the invention. In addition, the spring clip 32 be provided with additional lips that facilitate positioning during assembly and / or locking in operation.

In 5 is exemplary and not limiting the bushing 28 with the floating bearing 20 the servo unit according to the invention 10 shown in cross section. The floating bearing 20 is with its inner bearing ring 22 on the motor shaft 14 placed. With the outer bearing ring 24 borders the floating bearing 20 to the bearing bush 28 , The floating bearing 20 is with a clearance fit in the bearing bush 28 admitted.

In 5 The hatched area marks the game between the floating bearing 20 and the bearing bush 28 , Here, the game has here only in the Y direction freedoms. Cheeks of the bearing bush lead in the X direction 28 the outer bearing ring 24 , This results in the X direction, a very low clearance, which is a displacement of the floating bearing 20 allowed in Y direction. a shift of the floating bearing 20 prevented in the X direction, however, so that no acoustic interference can occur. The cross hatched area of the hatched area is for receiving the biasing device according to the invention 30 intended.

According to the invention it is also possible that in the X direction, a clearance between the bearing bush 28 and the outer bearing ring 24 consists. This space is preferably lined with mechanically and acoustically insulating material. This material can also be partial areas of the spring-damping element 34 be.

LIST OF REFERENCE NUMBERS

10

servo unit

12

engine

14

motor shaft

16

wheel

18

fixed bearing

20

movable bearing

22

inner bearing ring

24

outer bearing ring

26

casing

28

bearing bush

30

biasing means

32

spring clip

34

Spring-damping element

36

upper lifting point

38

lower lifting point

40

steering system

42

steering gear

44

propeller shaft

46

steering column

48

steering shaft

50

steering linkage

52

sealing plug

54

rotor pack

56

stator

X

X-direction

Y

Y-direction

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1866195 B1 [0002]
• DE 102007047369 A1 [0003]

Claims (10)

Pretensioning device ( 30 ), for acting on a bearing bush ( 28 ) stored stock ( 18 . 20 ) with a spring force, with a band-shaped, elastically deformable and self-damping properties having spring-damping element ( 34 ). Biasing device according to claim 1, characterized in that the pretensioning device ( 30 ) a spring clip ( 32 ) having two legs, wherein the spring-damping element ( 34 ) between the legs of the spring clip ( 32 ) is arranged. Biasing device according to claim 1 or 2, characterized in that the spring clip ( 32 ) is already biased to each other in a parallel position of the two legs. Biasing device according to one of claims 1 to 3, characterized in that the spring-damping element ( 34 ) is formed of at least one elastomer. Biasing device according to one of claims 1 to 4, characterized in that the spring-damping element ( 34 ) a height less than a distance between the two legs of the spring clip ( 32 ) in a parallel position. Servo unit ( 10 ) with at least one pretensioning device ( 30 ) according to one of claims 1 to 5, an engine ( 12 ) and one a motor shaft ( 14 ), wherein the motor shaft ( 14 ) in a camp ( 18 ) and a floating bearing ( 20 ) rotatably supported by the engine ( 12 ) is drivable, the floating bearing ( 20 ) resiliently in the bearing bush ( 28 ) and the fixed storage ( 18 ) is angularly adjustable and the motor shaft ( 14 ) thereby with the fixed bearing ( 18 ) as a fulcrum between an upper lifting point ( 36 ) and a lower attachment point ( 38 ) is pivotable, wherein the biasing means ( 30 ) in the bearing bush ( 28 ) on an outer bearing ring ( 24 ) of the floating bearing ( 20 ) and on the floating bearing ( 20 ) a bias by the biasing means ( 30 ) is applied. Servo unit according to claim 6, characterized in that the upper attachment point ( 36 ) is reached when the pretensioning device ( 30 ) is brought to block and the motor shaft ( 14 ) in the upper attachment point ( 36 ) centric to the engine ( 12 ) is aligned. Steering system ( 40 ) with a steering column ( 46 ), Steering linkage ( 50 ), the steering column ( 46 ) and the steering linkage ( 50 ) interconnecting steering gear ( 42 ) and a servo unit ( 10 ) according to claim 6 or 7. Steering system according to claim 5, characterized in that the servo unit ( 10 ) in the steering column ( 46 ) is integrated. Motor vehicle with a steering system according to claim 8 or 9.

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