DE102018128496B4 - Swivel bearing for steering system - Google Patents

Abstract

Pivot bearing (6) for supporting a worm shaft (4) of a steering system (1), comprising an inner ring (11) and an outer ring (12), with a plurality of rolling elements (13) between the inner ring (11) and the outer ring (12) is arranged, and with a pivot ring (14) in which the outer ring (12) is pivotably received, the pivot ring (14) being received in a tolerance ring (15), wherein on an outer surface of the tolerance ring (15) prestressing elements (18, 19) are characterized in that the prestressing elements (18, 19) are designed in the form of ribs (18) and plateaus (19) which are carried by a ring carrier (20).

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.

In modern motor vehicles, steering systems are used in which the steering movement of the driver is reduced by means of an appropriate steering force assistance. This can be done in a known manner by hydraulic power steering or by electrical or electrohydraulic steering assistance. 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 produce 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 transversely 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 pretensioning force on the worm shaft in the direction of the worm wheel. The worm shaft can thus tilt around the pivot 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 B3 a steering system with a gear unit for a motor vehicle is known which comprises a worm shaft which cooperates with a worm wheel. In order to optimize the engagement between the worm shaft and the worm wheel, it is provided that a pivot bearing can be tilted relative to the housing of the steering system. In this case, rubber-elastic elements are provided between the pivot bearing and the housing, which cause a radial and axial support of the tilting bearing in the housing. Furthermore, a spring element is provided for generating an axial prestressing force.

WO 2018/069 423 A1 describes a pivot bearing for mounting a worm shaft of a steering system, comprising an inner ring and an outer ring. Furthermore, a swivel ring is provided in which the outer ring is swivellably received, the swivel ring being received in a tolerance ring, with prestressing elements being formed on an outer surface of the tolerance ring

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

The object of the invention is to propose a swivel bearing for a steering system which does not negatively affect the swivel behavior and also minimizes the development of noise at the swivel 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 swivel ring in which the outer ring is pivotably received . It is provided that the swivel ring is received in a tolerance ring, with prestressing elements being formed on an outer surface of the tolerance ring. The pretensioning elements on the outer surface of the tolerance ring allow a simple tolerance compensation between the pivot bearing and the housing of the worm gear, whereby a uniform pivoting of the roller bearing in the pivot bearing can be realized over the life of the pivot bearing. The swivel function is not influenced by the tolerance ring and the geometric play between the housing and the swivel bearing can be safely eliminated. This dampens vibrations and noises between the pivot bearing and the housing of the worm gear, so that 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 design 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 facilitates pivoting.

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

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 operationally reliable tolerance compensation. A particularly simple and quick installation of the pivot bearing in the gear housing of the worm gear is thereby possible.

According to the invention it is provided that the prestressing elements are designed in the form of ribs and plateaus which are supported by a ring carrier. In this context, ribs are to be understood as meaning local elevations which protrude in the radial direction beyond a ring carrier of the tolerance ring. In this context, plateaus are to be understood as meaning elevations which are 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. By means of plateaus and ribs, a structure can be created which is both sufficiently rigid to avoid excessive radial deflection of the pivot bearing and sufficiently elastic so as not to negatively influence the pivoting of the pivot bearing. The radial rigidity of the pivot bearing can be adjusted through the specific design of the ribs and plateaus, the selection of the material, the material hardness and the number of ribs and plateaus. With the combination of ribs and plateaus, another advantage is that there is no play between the pivot bearing and the housing and the radial deflection, for example in the event of impacts from poor road surface conditions, is limited by the plateaus. For this purpose, the ribs in the unloaded initial state before assembly protrude slightly in the radial direction over the plateaus. 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 eliminate the play in the radial direction.

It is preferred if the ribs and the plateaus are arranged alternately in the direction of rotation. As a result, short contact sections in which the tolerance ring rests on the housing with a rib and longer contact sections in which the tolerance ring rests on the housing with a plateau alternate. Through these ribs and plateaus, as well as the grooves between the ribs and plateaus, the rigidity of the tolerance ring can be specifically influenced and adapted for the corresponding mounting.

It is particularly preferred if the ribs and the plateaus are arranged distributed uniformly over the circumference of the outer surface. A uniform arrangement of the ribs and plateaus over the circumference means that no positional orientation is necessary when assembling 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 positively received in the tolerance ring. A positive connection between the tolerance ring and the swivel ring can be used to produce an operationally reliable connection, with the load on the tolerance ring being kept low compared to a press connection. This prevents plastic deformation of the tolerance ring when it is pushed onto the swivel ring.

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

Alternatively, it is advantageously provided that the tolerance ring protrudes beyond the pivot ring in the axial direction. In this case, a collar is formed on the tolerance ring, which protrudes in the radial direction inward over the ring carrier of the tolerance ring and receives the swivel ring on its outer surfaces in a form-fitting manner. In this way, a reliable and stable connection can be established between the tolerance ring and the swivel ring without preloading the swivel ring in the radial direction against the outer ring of the roller bearing and thus making the swiveling 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. By means of a steering system according to the invention, the driver's steering forces can be transmitted simply and safely to the steering axle, the pivot bearing creating an adequate tolerance compensation for the housing. Noise and vibrations are reliably avoided by the pivot bearing.

In an advantageous embodiment of the steering system it is provided that the tolerance ring is pressed into the housing. By pressing in the tolerance ring, simple and inexpensive assembly of the steering system is possible.

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

• 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;
• 2 a pivot bearing according to the invention with a tolerance ring;
• 3 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 one embodiment of a steering system 1 with a pivot bearing according to the invention 6th shown. The steering system has a worm gear 2 on, with which a steering torque from a worm shaft 4th on a worm wheel 3 is transmitted. This is on the worm wheel 3 a toothing 7th formed, which with a toothed portion 8th the worm shaft 4th is engaged. The worm shaft 4th is at at least one storage location 5 , preferably at at least two storage locations 5 in one housing 26th of the worm gear 2 rotatably mounted. The storage of the worm shaft 4th takes place by means of a swivel bearing 6th . The steering system 1 is preferred as an electrically assisted steering system 1 executed. This includes the steering system 1 an electric steering assistance 9 , with which the steering forces of the driver are supported in order to change the steering angle.

2 shows a pivot bearing according to the invention 6th for a steering system 1 with a tolerance ring 15th . The swivel bearing 6th is called a rolling bearing 10 executed and has an inner ring 11 and an outer ring 12 on, between which a plurality of rolling elements 13 is arranged. The outer ring 12 of the swivel bearing 6th can be tilted in a swivel ring 14th of the swivel bearing 6th added, which allows a pivoting or tilting movement and thus an axial compensation in the pivot bearing. The tolerance ring 25th has a ring carrier 20th on, which on its radially outer end face 25th a multitude of ribs evenly distributed over the circumference 18th and plateaus 19th having, the ribs 18th and the plateaus 19th are arranged alternately in the circumferential direction and are each separated from one another by a groove. By the contour of the tolerance ring 15th with the ribs 18th and the plateaus 19th is a low radial preload of the pivot bearing 6th to the housing 26th of the worm gear 2 possible without the swivel function of the swivel bearing 6th affect negatively. The tolerance ring 15th with an overlap to the housing 26th assembled. Due to the special outer contour of the tolerance ring 15th becomes the swivel behavior of the swivel bearing 6th not influenced and the bearing play to the housing 26th of the worm gear 2 eliminated.

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

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

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

List of reference symbols

1

Steering system

2

Worm gear

3

Worm wheel

4th

Worm shaft

5

Depository

6th

Pivot bearing

7th

Interlocking

8th

Gear section

9

Electric steering assistance

10

roller bearing

11

Inner ring

12

Outer ring

13

Rolling elements

14th

Swivel ring

15th

Tolerance ring

16

Cage

17th

poetry

18th

rib

19th

plateau

20th

Ring bearer

21st

collar

22nd

Outer surface

23

shoulder

24

Bullet

25th

Face

26th

casing

Claims (9)

Pivot bearing (6) for mounting a worm shaft (4) of a steering system (1), comprising an inner ring (11) and an outer ring (12), with a plurality of rolling elements (13) between the inner ring (11) and the outer ring (12) is arranged, and with a pivot ring (14) in which the outer ring (12) is pivotably received, the pivot ring (14) being received in a tolerance ring (15), wherein on an outer surface of the tolerance ring (15) prestressing elements (18, 19) are 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) Claim 1 , characterized in that the prestressing elements (18, 19) are formed on a radially outer end face (25) of the tolerance ring (15). Swivel bearing (6) Claim 1 , characterized in that the ribs (18) and the plateaus (19) are arranged alternately in the direction of rotation. Swivel bearing (6) Claim 1 or 3 , characterized in that the ribs (18) and the plateaus (19) are arranged distributed uniformly over the circumference of the outer surface. Swivel bearing (6) according to one of the Claims 1 to 4th , characterized in that the swivel ring (14) is positively received in the tolerance ring (15). Swivel bearing (6) Claim 5 , characterized in that a shoulder (23) is formed on an outer surface of the pivot ring (15), the shoulder (23) being positively received in the tolerance ring (15). Swivel bearing (6) Claim 5 , characterized in that the tolerance ring (15) protrudes in the axial direction over the pivot ring (14). 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 7th is rotatably mounted in a housing (26) of the worm gear (1). Steering system (1) Claim 8 , characterized in that the tolerance ring (15) is pressed into the housing (26).

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