DE102018128496A1 - Swivel bearing for steering system - Google Patents

Abstract

The invention relates to a swivel bearing (6) for mounting a worm shaft (4) of a steering system (1) comprising an inner ring (11) and an outer ring (12), a plurality of rolling elements between the inner ring (12) and the outer ring (12) (13) is arranged, and with a swivel ring (14) in which the outer ring (12) is pivotally received. It is provided that the swivel ring (14) is received in a tolerance ring (15), prestressing elements (18, 19) being formed on an outer surface of the tolerance ring (15). The invention further relates to a steering system (1) with such a swivel bearing (6).

Description

The invention relates to a pivot bearing for mounting a worm shaft of a steering system and a steering system with such a pivot bearing.

Steering systems are used in modern motor vehicles in which the steering movement of the driver is reduced by a corresponding steering force support. This can be done in a known manner by hydraulic power steering or by electrical or electrohydraulic power steering. In addition, steering systems are known which generate a steering torque on the vehicle side in order to inform the driver of the motor vehicle of a recommended steering movement. In electrically assisted steering systems, an electric drive motor is usually used, which acts on the worm shaft via a worm gear in order to bring about a correspondingly high steering torque for turning the vehicle wheels.

Solutions are known from the prior art in which the worm shaft is mounted on a side facing the drive shaft via a first roller bearing in a housing which is designed as a pivot bearing and allows a certain tilting movement transverse to the axial direction of the worm shaft. The worm shaft is supported at its opposite end section by means of a second roller bearing, which is connected to a gear housing of the worm gear via a spring, which causes a biasing force on the worm shaft in the direction of the worm wheel. As a result, the worm shaft can tilt around the swivel bearing as required in order to achieve a substantially constant engagement of the toothing on the worm shaft with the worm wheel.

From the DE 10 2016 221 076 A1 a steering system with a gear unit for a motor vehicle is known which comprises a worm shaft which interacts with a worm wheel. In order to optimize the engagement between the worm shaft and the worm wheel, it is provided that a rotary bearing can be tilted relative to the housing of the steering system. Rubber-elastic elements are provided between the pivot bearing and the housing, which bring about radial and axial support of the tilting bearing in the housing. A spring element is also provided for generating an axial preload force.

A disadvantage of the known solutions, however, is that either the swivel range is severely restricted or unwanted noises can occur during use due to excessive play.

The object of the invention is to propose a pivot bearing for a steering system which does not negatively influence the pivoting behavior and also minimizes the noise development on the pivot bearing.

According to the invention, this object is achieved by a pivot bearing for a steering system for mounting a worm shaft of a worm gear with an inner ring and an outer ring, a plurality of rolling elements being arranged between the inner ring and the outer ring, and with a pivot ring in which the outer ring is pivotably received . It is provided that the swivel ring is accommodated in a tolerance ring, prestressing elements being formed on an outer surface of the tolerance ring. The prestressing elements on the outer surface of the tolerance ring allow for a simple tolerance compensation between the pivot bearing and the housing of the worm gear, as a result of which a uniform pivoting of the roller bearing in the pivot bearing can be achieved over the service life of the pivot bearing. The swivel function is not affected by the tolerance ring and the geometrical play between the housing and the swivel bearing can be reliably removed. This dampens vibrations and noise between the pivot bearing and the housing of the worm gear, whereby the source of the noise can be largely eliminated. Compared to a tolerance ring between the outer ring of the roller bearing and the swivel ring, the proposed construction achieves a significant improvement, since the convex surface on the outer ring of the roller bearing and the concave surface on the swivel ring can be ground accordingly, which makes pivoting easier.

The features listed in the dependent claims allow advantageous improvements and further developments of the pivot bearing specified in the independent claim.

In a preferred embodiment of the pivot bearing it is provided that the prestressing elements are formed on a radially outer end face of the tolerance ring. The arrangement of the prestressing elements on the radially outer end face enables simple manufacture and assembly of the tolerance ring. In principle, it would also be conceivable for elastic elements to be formed on the outer surface of the tolerance ring, but the radial play on the end face is decisive for reliable tolerance compensation. This enables particularly simple and quick assembly of the pivot bearing in the gear housing of the worm gear.

In a further improvement of the invention it is provided that the prestressing elements are designed in the form of ribs and plateaus which are carried by a ring carrier. In this context, ribs are to be understood as local elevations which protrude in the radial direction over a ring carrier of the tolerance ring. In this context, plateaus are to be understood as elevations which have at least 2.5 times the width, preferably at least three times the width, particularly preferably at least 3.5 times the width of the ribs. A structure can be created by plateaus and ribs, which is both sufficiently rigid to avoid excessive radial deflection of the pivot bearing and sufficiently elastic to not negatively influence the pivoting of the pivot bearing. The radial stiffness of the pivot bearing can be adjusted by the specific design of the ribs and plateaus, the selection of the material, the material hardness and the number of ribs and plateaus. Another advantage of the combination of ribs and plateaus is that the freedom from play between the pivot bearing and the housing is realized and the radial deflection, for example in the event of impacts due to poor road conditions, is limited by the plateaus. For this purpose, the ribs protrude slightly above the plateaus in the radial direction before assembly in the unloaded state. If the pivot bearing is inserted into the housing, there is a deformation in the area of the ribs, which is preferably in the range of 0.05-0.15 mm, in order to preload the pivot bearing and to eliminate the play in the radial direction.

It is preferred if the ribs and the plateaus are arranged alternately in the direction of rotation. This alternates between short contact sections in which the tolerance ring rests with a rib on the housing and longer contact sections in which the tolerance ring lies against the housing with a plateau. Through these ribs and plateaus, as well as the grooves between the ribs and plateaus, the stiffness of the tolerance ring can be influenced in a targeted manner and adapted for the corresponding bearing.

It is particularly preferred if the ribs and the plateaus are arranged evenly distributed over the circumference of the outer surface. Due to the uniform arrangement of the ribs and plateaus over the circumference, no orientation is necessary when mounting the tolerance ring. The assembly of the pivot bearing and the steering system can thus be simplified.

In a preferred embodiment of the invention it is provided that the swivel ring is received in a form-fitting manner in the tolerance ring. A form-fitting connection between the tolerance ring and the swivel ring enables a reliable connection to be established, the load on the tolerance ring being able to be kept low in comparison to a press connection. This prevents plastic deformation of the tolerance ring when it is slid onto the swivel ring.

It is preferred if a shoulder is formed on an outer surface of the swivel ring, the shoulder of the swivel ring being received in a form-fitting manner in the tolerance ring. A shoulder on the swivel ring enables a particularly stable and reliable form-fitting connection between the swivel ring and the tolerance ring.

Alternatively, it is advantageously provided that the tolerance ring projects beyond the swivel ring in the axial direction. In this case, a collar is formed on the tolerance ring, which protrudes inward in the radial direction beyond the ring carrier of the tolerance ring and receives the swivel ring in a form-fitting manner on its lateral surfaces. An operationally reliable and stable connection can thus be established between the tolerance ring and the swivel ring without prestressing the swivel ring in the radial direction against the outer ring of the rolling bearing and thus making pivoting more difficult.

According to the invention, a steering system with a worm gear and a worm shaft is proposed, the worm shaft being rotatably mounted in a housing by means of a pivot bearing according to the invention. The steering forces of the driver can be easily and safely transmitted to the steering axle by means of a steering system according to the invention, the swivel bearing providing sufficient tolerance compensation for the housing. Noises and vibrations are reliably avoided by the swivel bearing.

In an advantageous embodiment of the steering system it is provided that the tolerance ring is pressed into the housing. Pressing in the tolerance ring enables the steering system to be installed simply and inexpensively.

Unless otherwise stated in the individual case, the various embodiments of the invention mentioned in this application can advantageously be combined with one another.

• 1 ein Ausführungsbeispiel eines erfindungsgemäßen Lenksystems mit einem erfindungsgemäßen Schwenklager;
• 2 ein erfindungsgemäßes Schwenklager mit einem Toleranzring;
• 3 ein Teilsegment eines Toleranzrings für ein erfindungsgemäßes Schwenklager in einer schematischen Darstellung;
• 4 ein Ausführungsbeispiel für ein erfindungsgemäßes Schwenklager in einer Schnittdarstellung; und
• 5 ein weiteres Ausführungsbeispiel eines erfindungsgemäßen Schwenklagers in einer Schnittdarstellung.

The invention is explained below using a preferred exemplary embodiment and the associated drawings. Show it:

• 1 an embodiment of a steering system according to the invention with a pivot bearing according to the invention;
• 2nd an inventive pivot bearing with a tolerance ring;
• 3rd a partial segment of a tolerance ring for a pivot bearing according to the invention in a schematic representation;
• 4th an embodiment of a pivot bearing according to the invention in a sectional view; and
• 5 a further embodiment of a pivot bearing according to the invention in a sectional view.

In 1 is an embodiment of a steering system 1 with a pivot bearing according to the invention 6 shown. The steering system has a worm gear 2nd with which a steering torque from a worm shaft 4th on a worm wheel 3rd is transmitted. This is on the worm wheel 3rd a gearing 7 formed which with a toothed section 8th the worm shaft 4th is engaged. The worm shaft 4th is at at least one storage location 5 , preferably at at least two bearings 5 in one housing 26 of the worm gear 2nd rotatably mounted. The storage of the worm shaft 4th takes place by means of a swivel bearing 6 . The steering system 1 is preferably an electrically assisted steering system 1 executed. The steering system also includes this 1 an electric steering assist 9 , with which the steering forces of the driver are supported in order to change the steering angle.

2nd shows an inventive pivot bearing 6 for a steering system 1 with a tolerance ring 15 . The swivel bearing 6 is as a rolling bearing 10th executed and has an inner ring 11 and an outer ring 12th between which a plurality of rolling elements 13 is arranged. The outer ring 12th of the swivel bearing 6 is tiltable in a swivel ring 14 of the swivel bearing 6 added, which enables a pivoting or tilting movement and thus axial compensation in the pivot bearing. The tolerance ring 25th has a ring bearer 20th on which on its radially outer end face 25th a variety of ribs evenly distributed over the circumference 18th and plateaus 19th has, the ribs 18th and the plateaus 19th are arranged alternately in the circumferential direction and each separated by a groove. Through the contour of the tolerance ring 15 with the ribs 18th and the plateaus 19th is a slight radial preload of the swivel bearing 6 to the housing 26 of the worm gear 2nd possible without the swivel function of the swivel bearing 6 to affect negatively. The tolerance ring 15 with a cover to the housing 26 assembled. Due to the special outer contour of the tolerance ring 15 becomes the swivel behavior of the swivel bearing 6 not affected and the bearing play to the housing 26 of the worm gear 2nd eliminated.

In 3rd is a section through a ring segment of the tolerance ring 15 shown. It can be seen that the ribs 18th and the plateaus 19th from the ring bearer 20th project outwards in the radial direction and thus the radially outer end face 25th of the tolerance ring 15 form.

In 4th is a section through a pivot bearing according to the invention 6 shown. The swivel bearing 6 includes an inner ring 11 and an outer ring 12th , between which a large number of rolling elements 13 are arranged. The rolling elements are preferred 13 as bullets 24th executed by a guide track on the inner ring 11 and a guideway on the outer ring 12th be performed. There is also a cage 16 provided which is the distance between the rolling elements 13 Are defined. The swivel bearing 6 also has sealing elements 17th to prevent lubricant from escaping from the pivot bearing 6 to avoid. The outer ring 12th is in a swivel ring 14 taken tiltable in the axial direction. To do this, the outer ring 12th on its radially outer surface a convex shape and the swivel ring 14 has a concave shape on its radially inner surface, so that a compensating movement between the outer ring 12th and the swivel ring 14 is possible. The swivel ring 14 is in the tolerance ring 15 added with the tolerance ring 15 the radially outer end faces 25th of the swivel bearing 6 trains. The tolerance ring 15 has a collar 21st on which on a lateral surface 22 the swivel ring 14 is applied, whereby the tolerance ring 15 form-fitting with the swivel ring 14 connected is.

In 5 is a further embodiment of a pivot bearing according to the invention 6 disclosed in a sectional view. The swivel bearing 6 includes a rolling bearing as in the previous embodiment 10th with an inner ring 11 and an outer ring 12th , which can be tilted in a swivel ring 14 is included. The swivel ring 14 has at least one shoulder on its outer end face 23 , preferably as in 5 shown two shoulders 23 , on which a collar 21st of the tolerance ring 15 is positively received. This allows the width of the pivot bearing 6 be reduced because of the tolerance ring 15 not over the swivel ring in the axial direction 15 must protrude, but can be flush with this.

Reference symbol list

1

Steering system

2nd

Worm gear

3rd

Worm wheel

4th

Worm shaft

5

Depository

6

Swivel bearing

7

Gearing

8th

Gear section

9

Electric steering assistance

10th

roller bearing

11

Inner ring

12

Outer ring

13

Rolling elements

14

Swivel ring

15

Tolerance ring

16

Cage

17th

poetry

18th

rib

19th

plateau

20th

Ring bearer

21

collar

22

Lateral surface

23

shoulder

24th

Bullet

25th

Face

26

casing

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included 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.

Patent literature cited

• DE 102016221076 A1 [0004]

Claims (10)

Pivot bearing (6) for mounting a worm shaft (4) of a steering system (1), comprising an inner ring (11) and an outer ring (12), a plurality of rolling elements (13) between the inner ring (12) and the outer ring (12) is arranged, as well as with a swivel ring (14), in which the outer ring (12) is pivotably received, characterized in that the swivel ring (14) is received in a tolerance ring (15), prestressing elements on an outer surface of the tolerance ring (15) (18, 19) are formed. Swivel bearing (6) after Claim 1 , characterized in that the biasing elements (18, 19) are formed on a radially outer end face (25) of the tolerance ring (15). Swivel bearing (6) after Claim 1 or 2nd , characterized in that the prestressing elements (18, 19) are in the form of ribs (18) and plateaus (19) which are carried by a ring carrier (20). Swivel bearing (6) after Claim 3 , characterized in that the ribs (18) and the plateaus (19) are arranged alternately in the circumferential direction. Swivel bearing (6) after Claim 3 or 4th , characterized in that the ribs (18) and the plateaus (19) are arranged evenly distributed over the circumference of the outer surface. Swivel bearing (6) according to one of the Claims 1 to 5 , characterized in that the swivel ring (14) is positively received in the tolerance ring (15). Swivel bearing (6) after Claim 6 , characterized in that a shoulder (23) is formed on an outer surface of the swivel ring (15), the shoulder (23) being received in a form-fitting manner in the tolerance ring (15). Swivel bearing (6) after Claim 6 , characterized in that the tolerance ring (15) projects beyond the swivel ring (14) in the axial direction. Steering system (1) with a worm gear (2) and a worm shaft (4), the worm shaft (4) by means of a pivot bearing (6) according to one of the Claims 1 to 8th is rotatably mounted in a housing (26) of the worm gear (1). Steering system (1) Claim 9 , characterized in that the tolerance ring (15) is pressed into the housing (26).

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