WO2020088709A1

WO2020088709A1 - Acoustically optimized bearing unit

Info

Publication number: WO2020088709A1
Application number: PCT/DE2019/100812
Authority: WO
Inventors: Martin Kruppa
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2018-10-30
Filing date: 2019-09-11
Publication date: 2020-05-07
Also published as: DE102018127029A1; CN112739921A; KR20210081327A

Abstract

The invention relates to a bearing unit (10) for the mounting of a shaft, having a bearing (12) with an inner ring (14) and an outer ring (16), wherein the inner ring (14) and the outer ring (16) are rotatable circumferentially with respect to each other, and wherein the outer ring (16) has an outer curved lateral surface (18), wherein the bearing (18) has a rotation axis (R) and is supported in relation to at least one pivot ring (20), and wherein the bearing (18) is pivotable in relation to the pivot ring (20) about at least one pivot axis (S) oriented transversely with respect to the rotation axis (R), wherein the pivot ring (20) has at least one inner surface (22) which is in the form of a spherical dome and is designed so as to correlate with the outer curved lateral surface (18) of the outer ring (16) in order to form a contact region (24), wherein the pivot ring (20), the inner ring (14) and the outer ring (16) are arranged coaxially with respect to one another, wherein the pivot ring (20) in the circumferential direction (U) has a recess (26) which extends over the entire pivot ring width. This creates a bearing unit (10) having good acoustic properties and which can easily be produced and mounted.

Description

Acoustically optimized storage unit

The invention relates to a bearing unit for supporting a shaft, comprising a bearing with an inner ring and an outer ring, the inner ring and the outer ring being rotatable in relation to one another circumferentially, and wherein the outer ring has an outer, curved outer surface, the bearing having an axis of rotation and is supported with respect to at least one swivel ring, and wherein the bearing can be swiveled with respect to the swivel ring about at least one swivel axis oriented transversely to the axis of rotation, the swivel ring having at least one inner surface designed as a spherical cap which correlates with the outer, curved one The outer surface of the outer ring is formed so that there is a contact area between these surfaces, the swivel ring, the inner ring and the outer ring being arranged coaxially to one another.

Drives with worm shafts and worm wheels are often used in electrically assisted power steering systems. The worm shaft is usually supported in a fixed bearing and a floating bearing. In some applications, the fixed bearing is designed as a swivel bearing and can adjust the wear in the tooth mesh and the shaft tilt. The swiveling function is provided by the use of a separate swivel ring with an inner sphere, which receives the spherical ball bearing outer ring. An electrically powered power steering is an electric power steering system that only works when steering movements take place. In the case of an electromechanical drive, a program-controlled electric servomotor supports and superimposes the driver's steering movements on the mechanics of the steering, i.e. on the steering column or steering gear. These systems are known as Electric Power Steering (EPS) and Electric Power Assisted Steering (EPAS), with the hydraulics always being omitted in these systems. This eliminates the servo pump, the hoses from the servo pump to the steering gear and back, the hydraulic fluid and the slave piston

Bearing designs for electrically assisted power steering systems are manufactured with high precision because the spherical cap should be as free of play as possible in order to to ensure low-noise function of the storage unit without envelope clacks. The outer ring and the swivel ring form a pair of calottes that are manufactured with precisely defined tolerances and are paired in several tolerance groups. The swivel ring has mounting windows for inserting and pivoting the spherical outer ring.

A bearing unit according to the prior art is known, for example, from published patent application DE 10 2007 044 618 A1. This invention is directed to a bearing unit by means of which a worm spindle for a power steering system is pivotably mounted. A pivotability of a bearing is ensured via two outer rings, which can be connected to one another for a changeable relative position by means of a connecting element in such a way that an outer surface of an outer bearing shell of the bearing is free of play but while ensuring a degree of freedom of pivoting about a pivot axis .

It is the object of the invention to create an alternative bearing unit with good acoustic properties, easy to assemble and a simple to produce outer ring and swivel ring, the bearing unit should be able to adjust wear in the tooth mesh and a shaft tilt.

The object is achieved according to the invention by a roller bearing with the features of claim 1. Preferred embodiments of the invention are specified in the subclaims and the following description, which can each represent an aspect of the invention individually or in combination.

The invention relates to a bearing unit for supporting a shaft, comprising a bearing with an inner ring and an outer ring, the inner ring and the outer ring being rotatable in relation to one another circumferentially, and wherein the outer ring has an outer, curved outer surface, the bearing having an axis of rotation and is supported with respect to at least one swivel ring, and wherein the bearing can be swiveled with respect to the swivel ring about at least one swivel axis oriented transversely to the axis of rotation, the swivel ring having at least one inner surface designed as a spherical cap which correlates with the outer, curved one Shell surface of the outer ring is formed to form a contact area, wherein the swivel ring, the inner ring and the outer ring are arranged coaxially to one another. The swivel ring has a recess in the circumferential direction, which extends over the entire width of the swivel ring.

The swivel ring width is the width that the swivel ring has over the extension axis of the axis of rotation.

The recess extending over the entire swivel ring width is provided so that the bearing, preferably a rolling bearing, particularly preferably a ball bearing, can be easily mounted in the swivel ring, the mounted bearing unit having good acoustic properties. The good acoustic properties are due in particular to the spring tension in the contact area between the spherical spherical inner surface of the swivel ring and the outer, curved outer surface of the outer bearing. Due to the constant voltage in the aforementioned contact area, noises caused by cover clacks are avoided.

The recess is particularly preferably produced by providing an indentation in the region of the future recess, which is further processed into the recess.

The swivel ring is in particular designed to be elastic so that the recess supports a resilient effect of the swivel ring.

Apart from the recess, the swivel ring is preferably designed to be rotationally symmetrical. It preferably has a spherical cap in its inner region.

In particular, the swivel ring consists of a hardening material, for example 100Cr6. This feature allows the swivel ring to be notched particularly well by means of laser beam cutting and therefore easy to manufacture.

Alternatively, the swivel ring can also be made from a non-hardening material, such as case hardening steel or sintered material. This makes the swivel ring particularly easy to saw to create a notch in the swivel ring. It is particularly preferably provided that the outer ring and the swivel ring are designed to overlap one another. Overlap can be understood in the same way as an interference fit. Because of the particularly elastic design of the swivel ring, in this preferred case the swivel ring acts like a spring that prestresses the spherical cap without play. This property can be used for play-free mounting of the shaft by fixing the swivel bearing in a non-positive or positive manner after mounting in the steering gear housing using a nut. The elastic pre-tension is retained after tightening the nut.

An alternative way of a play-free storage is that the

Swing ring on the outside in the circumferential direction has at least one elastic jacket element, in particular an O-ring. The swivel ring equipped with, for example, elastic rings or elastic sheathing enables permanent elastic pre-tensioning after installation. The elastic components also ensure noise isolation and vibration damping during operation.

Particularly preferably, the outer ring and / or the swivel ring can have a friction-reducing coating at least in the contact area. Coatings with a coefficient of friction of less than or equal to the coefficient of friction of molybdenum disulfide or manganese phosphate are deemed to be a friction-reducing coating. Molybdenum disulfide or manganese phosphate are particularly preferred coatings for the outer ring and / or the swivel ring.

A method according to the invention for producing a bearing unit with at least one of the aforementioned features provides that the swivel ring has at least one notch in order to form the recess. This notch is loaded or deformed in such a way that it breaks across the entire swivel ring width and subsequently forms the recess. The swivel ring is then elastically expanded in such a way that the bearing to be assembled can be inserted. After the swivel ring and the bearing to be assembled have the corresponding mounting position, the widening of the swivel ring is released in such a way that the swivel ring encompasses the circumference of the bearing. The expansion therefore only takes place transitional. This shows the ease of assembly, with the outer ring and the swivel ring being easy to manufacture.

According to a preferred measure, the notch for producing the bearing unit can originate from the fact that the notch is already present when a swivel ring green part is produced or that it is introduced by means of a laser beam. A swivel ring made of a hardening material, preferably 100Cr6, is particularly suitable for this.

According to an alternative measure for producing the notch, it is provided that the notch is introduced by means of a separating production process, for example by means of sawing or cutting. The cutting can preferably be done with a laser or water jet. Optionally, these manufacturing measures for the notch are particularly suitable for a swivel ring made of a non-hardening material. The swivel ring then particularly preferably consists of a case hardening steel or sintered material.

Furthermore, the invention relates to a swivel ring with at least one of the aforementioned features for a bearing with at least one of the aforementioned features.

In the following, the invention is explained by way of example with reference to the attached drawings using preferred exemplary embodiments, the features shown below being able to represent an aspect of the invention both individually and in combination. Show it:

1: a storage unit according to the prior art in a side view,

2: a bearing unit in a vertical sectional view through the section plane A-A according to FIG. 1,

3: a first embodiment of a bearing unit according to the teaching of the invention in a side view,

4: a storage unit in a vertical sectional view through the sectional plane B-B according to FIG. 3,

5: a bearing unit according to FIGS. 3 and 4 in a perspective view, 6 shows a bearing unit arranged in a power steering housing

3, 4 and 5 in a vertical sectional view,

7: a second embodiment of a bearing unit according to the teaching of the invention in a side view,

8: a bearing unit in a vertical sectional view through the sectional plane C-C according to FIG. 7,

9: a bearing unit according to FIGS. 7 and 8 in a perspective view and

10: a bearing unit arranged in a power steering housing according to

7, 8 and 9 in a vertical sectional view.

1 shows a bearing unit 10 according to the prior art in a side view. The bearing unit 10 has a bearing 12 with an inner ring 14 and an outer ring 16. The inner ring 14 and the outer ring 16 are circumferentially rotatable relative to one another about an axis of rotation R.

The bearing 12 is supported with respect to at least one swivel ring 20 and can be swiveled with respect to the swivel ring 20 by at least one swivel axis R oriented transversely to the axis of rotation R.

2 shows the bearing unit 10 in a vertical sectional view through the sectional plane A-A according to FIG. 1. It can be seen that the swivel ring 20 has an inner surface 22 designed as a spherical cap, which is designed to correlate with an outer, curved outer surface 18 of the outer ring 16 to form a contact region 24. The swivel ring 20, the inner ring 14 and the outer ring 16 are arranged coaxially to one another.

As can be seen in FIGS. 1 and 2, the swivel ring 20 according to the prior art has two diametrically opposed mounting windows 28, which are designed to be slot-like around the circumference of the swivel ring 20 and extend in particular up to half the swivel ring width into the swivel ring 20. The swivel ring width is the width which the swivel ring 20 has over the extension axis of the rotation axis R. The assembly windows 28 serve to insert and pivot the outer ring 16 with the outer, curved outer surface 18. An outer ring 16 with such an outer, curved outer surface 18 is also called a spherical outer ring.

3 shows a side view of a bearing unit 10 according to a first embodiment of the invention. The bearing unit 10 has a bearing 12 with an inner ring 14 and an outer ring 16. The inner ring 14 and the outer ring 16 are circumferentially rotatable relative to one another about an axis of rotation R.

The bearing 12 is supported with respect to at least one swivel ring 20 and can be swiveled with respect to the swivel ring 20 about at least one swivel axis S oriented transversely to the axis of rotation R.

4 shows the bearing unit 10 in a vertical sectional view through the sectional plane B-B according to FIG. 3. It can be seen that the swivel ring 20 has an inner surface 22 designed as a spherical cap, which is designed to correlate with an outer, curved outer surface 18 of the outer ring 16, so that there is a contact area 24 between these surfaces. The swivel ring 20, the inner ring 14 and the outer ring 16 are arranged coaxially with respect to one another with respect to the axis of rotation R.

3 to 6 also show that the swivel ring 20 has a recess 26 in the circumferential direction U which extends over the entire swivel ring width. The swivel ring width is the width which the swivel ring 20 has over the extension axis of the axis of rotation R.

According to the first embodiment, an elastic prestress between the outer ring 16 and the in particular elastic swivel ring 20, which continues after assembly, is formed by the outer ring 16 and the swivel ring 20 being designed to overlap one another. This means that there is an interference fit.

6 shows how the bearing unit 10 according to the first embodiment is arranged in a power steering housing 30. The bearing unit 10 can in particular be provided for mounting a worm shaft. This applies in particular to a system with a power steering housing 30 according to Electric Power As- sisted steering (EPAS). The pivot bearing 20 is fixed in a non-positive or positive manner via a threaded nut 32. The fixation takes place in particular with a spring-elastic pretension generated via the swivel ring 20 by means of the cover. This fixing method enables an advantageously firm and at the same time releasable connection of the bearing unit 10 in the power steering housing 30.

According to the invention, the mounting of the bearing unit 10 in the power steering housing 30 can be selected by means of the threaded nut 32 both in the first and in the second embodiment, as well as in a non-positive or positive manner in accordance with embodiments not shown.

7 shows a side view of a bearing unit 10 according to a second embodiment of the invention. The bearing unit 10 has a bearing 12 with an inner ring 14 and an outer ring 16. The inner ring 14 and the outer ring 16 are circumferentially rotatable relative to one another about an axis of rotation R.

8 shows the bearing unit 10 in a vertical sectional view through the sectional plane C-C according to FIG. 7. It can be seen that the swivel ring 20 has an inner surface 22 designed as a spherical cap, which is designed to correlate with an outer, curved outer surface 18 of the outer ring 16, so that there is a contact area 24 between these surfaces. The swivel ring 20, the inner ring 14 and the outer ring 16 are arranged coaxially with respect to one another with respect to the axis of rotation R.

7 to 10 also show that the swivel ring 20 has a recess 26 in the circumferential direction U which extends over the entire swivel ring width. The swivel ring width is the width which the swivel ring 20 has over the extension axis of the axis of rotation R.

An elastic prestress between the outer ring 16 and the particularly elastic swivel ring 20, and which persists after assembly, is according to the second embodiment formed by the pivot ring 20 on the outside in the circumferential direction U has at least one elastic jacket element 36. 8, 9 and 10 show that two elastic jacket elements 36, which are in particular O-rings, are provided which are spaced apart from one another over the swivel ring width.

10 shows how the bearing unit 10 according to the second embodiment is arranged in a power steering housing 30. The bearing unit 10 can in particular be provided for mounting a worm shaft. This applies in particular to a system with a power steering housing 30 according to Electric Power Assisted Steering (EPAS). The swivel bearing 20 is fixed in the power steering housing 30 via a snap ring 34. The fixation takes place in particular with a spring-elastic pretension generated via the swivel ring 20 by means of the elastic jacket elements 36. This fixing method enables an advantageously inexpensive and at the same time detachable connection of the bearing unit 10 in the power steering housing 30.

According to the invention, the mounting of the bearing unit 10 in the power steering housing 30 can be selected by means of the snap ring 34 both in the first and in the second embodiment, as well as in accordance with embodiments not shown, in particular in a non-positive or positive manner.

Reference list

10 storage unit

12 bearings

14 inner ring

16 outer ring

18 outer surface of the outer ring

0 swivel ring

22 inner surface

24 contact area

26 recess

28 assembly windows

30 power steering housing

32 threaded nut

34 snap ring

36 elastic jacket elements

R axis of rotation

S swivel axis

U circumferential direction

Claims

1. Bearing unit for bearing a shaft, having

a bearing (12) with an inner ring (14) and an outer ring (16), the inner ring (14) and the outer ring (16) being rotatable relative to one another circumferentially, and the outer ring (16) having an outer, curved outer surface ( 18), the bearing (18) having an axis of rotation (R) and being supported in relation to at least one swivel ring (20), and the bearing (18) in relation to the swivel ring (20) by at least one transverse to the axis of rotation (R) oriented pivot axis (S) is pivotable,

wherein the swivel ring (20) has at least one inner surface (22) designed as a spherical cap, which is designed to correlate with the outer, curved outer surface (18) of the outer ring (16) to form a contact area (24),

the swivel ring (20), the inner ring (14) and the outer ring (16) being arranged coaxially to one another,

characterized,

that the swivel ring (20) has a recess (26) in the circumferential direction (U), which extends over the entire swivel ring width.

2. Bearing unit according to claim 1, characterized in that the outer ring (16) and / or the swivel ring (20) has / have an anti-friction coating at least in the contact area (24).

3. Bearing unit according to claim 1 or 2, characterized in that the friction-reducing coating has molybdenum disulfide or manganese phosphate.

4. Bearing unit according to one of the preceding claims, characterized in that the outer ring (16) and the swivel ring (20) are designed to overlap one another.

5. Bearing unit according to one of the preceding claims, characterized in that the swivel ring (20) on the outside in the circumferential direction (U) has at least one elastic jacket element 36, in particular an O-ring.

6. Bearing unit according to one of the preceding claims, characterized in that the swivel ring (20) consists of a hardening material, preferably 100Cr6.

7. A method for producing a storage unit (10) according to one of the preceding claims, characterized in that

- That the swivel ring (20) has at least one notch to form the recess (26),

- The notch is loaded in such a way that it breaks over the entire swivel ring width and forms the recess (26),

- That the swivel ring (20) is expanded elastically such that the bearing (12) to be assembled can be inserted, and

- That the expansion of the swivel ring (20) is released in such a way that the swivel ring (20) encompasses the bearing (12) circumferentially.

8. A method for producing a bearing unit (10) according to the aforementioned claim, characterized in that the notch is already present with the manufacture of a swivel ring green body or that it is introduced by means of a laser beam.

9. A method for producing a bearing unit (10) according to one of claims 7 or 8, characterized in that the notch is introduced by means of a separating production method, for example by means of sawing or cutting, the pivot ring (20) preferably not being made of one -curing material, in particular from a case hardening steel or sintered material.

10. Swivel ring for a bearing unit (10) according to one of the preceding claims, characterized by the features of the swivel ring (20) according to one of the preceding claims.