WO2008028467A1

WO2008028467A1 - Bearing arrangement having an integrated oscillation drive

Info

Publication number: WO2008028467A1
Application number: PCT/DE2007/001562
Authority: WO
Inventors: Rupert Stitzinger
Original assignee: Schaeffler Kg
Priority date: 2006-09-05
Filing date: 2007-09-04
Publication date: 2008-03-13
Also published as: DE102006041630A1

Abstract

The invention relates to a bearing arrangement for mounting rotating machine elements, which bearing arrangement comprises an oscillation drive. A bearing arrangement according to the invention comprises a first and a second bearing ring which are arranged such that they can rotate with respect to one another. Furthermore, the bearing arrangement comprises an oscillation element which is required for the drive and a friction element which is associated with the former. The oscillation element and the friction element are arranged within an annular hollow space which is formed between the bearing rings. The oscillation element for generating oscillations is connected fixedly in terms of rotation to the first bearing ring and is operatively connected to the friction element which is connected fixedly in terms of rotation to the second bearing ring. If the oscillation element is made to oscillate, wherein the surface of the oscillation element performs, for example, elliptical movements, it exerts an advancing force on the friction element which experiences a torque on account of its rotatable mounting via the second bearing ring and rotationally drives a machine element which is received in the second bearing ring. A complete oscillation drive is therefore formed within the bearing arrangement.

Description

Name of the invention

Storage arrangement with integrated vibration drive

description

Field of the invention

The invention relates to a storage arrangement for supporting rotating machine elements comprising a vibration drive.

Vibration drives, which are also referred to as traveling wave drives and are often designed as ultrasonic drives, are increasingly being used as actuators, for example in precision mechanics and in motor vehicle technology. They are characterized by a high power density, by a simple mechanical structure and by a positioning accuracy in the nanometer range.

From DE 30 10 252 C2 a drive device with an oscillator is known, in which the transmission of the torque takes place over a plurality of spring-mounted components. A preferred embodiment of this device comprises a rotor which is rotatably mounted in ball bearings. An end face of the rotor is integrally formed with vibrating pieces and is operatively connected to a vibrating plate.

be an axially arranged ultrasonic oscillator. The ball bearings are loaded in particular in the axial direction, since the vibrating disk exerts forces in the axial direction on the rotor. Therefore, the running surfaces of the ball bearings have a special shape for receiving the axially acting forces. The ball bearings are located near the vibrating end face of the rotor. This ensures that the lateral forces occurring at the end face can not exert a high tilting torque on the ball bearings. A disadvantage of this solution is the large space required for the ultrasonic oscillator. In addition, this solution can be realized only at one axial end of a rotating machine element, whereby the applicability is significantly limited.

From DE 690 26 650 T2 an ultrasonic motor for rotating a rotor is known, in which a vibration generated in a vibrating element

Wave is used. The motor comprises a rotor which is rotatably mounted on a carrier with a ball bearing. On the carrier is still the

Attached vibrating element, which acts laterally on the rotor. One of the

Supported pressure-regulating spring acts on the inner ring of the ball bearing and generates in this way a contact pressure between the

Rotor and the vibrating element. This solution also has the disadvantage of being able to be realized only at one axial end of a rotating machine element, since the carrier is arranged in the axis of rotation of the motor. Another disadvantage is the space required for the vibrating element in the peripheral area of the ball bearing.

An object of the present invention is thus to minimize the storage and drive required for a rotating machine element bearings and drives in terms of their space requirements and to provide a drive for rotating machine elements available, which need not be arranged at one axial end of the rotating machine element , This object is achieved by a storage arrangement according to the appended claim 1.

A storage arrangement according to the invention comprises a first and a second bearing ring which are arranged rotatable relative to one another. Furthermore, the storage arrangement comprises a required for the drive vibrating element and an associated friction element. The oscillating member and the friction member are disposed within an annular cavity formed between the inner and outer peripheries of the bearing assembly formed by the bearing rings. The vibrating element for generating vibrations is rotatably connected to the first bearing ring and is in operative contact with the friction element, which is non-rotatably connected to the second bearing ring. If the oscillating element is caused to oscillate, wherein the surface of the oscillating element carries out elliptical movements, it will supply a thrusting force to the friction element, which due to its bearing rotatable via the second bearing ring experiences a torque and drives a machine element accommodated in the second bearing ring for rotation. Thus, a complete oscillation drive is formed within the storage arrangement according to the invention.

A particular advantage of the storage arrangement according to the invention is that it simultaneously forms a means for storage and a means for driving a rotatable machine element. Due to this double function, the space requirement for these funds is significantly reduced. The drive forms a compact assembly and can replace an existing bearing of a machine. The vibration drive allows a high speed with a moderate torque. Furthermore, the vibration drive allows a backlash-free actuator that allows very fast and very accurate adjustments. Another advantage of the storage arrangement according to the invention is that it can act as a controllable brake at the same time by the vibrating element is excited to a corresponding deformation or corresponding vibrations. But the braking force and the driving force can also be completely withdrawn, so that the bearing assembly can rotate freely.

Preferably, a spring element is arranged between the oscillating element and the first bearing ring, which presses the oscillating element against the friction element. As a result, a secure and reliable operative connection between the vibrating element and the friction element is ensured. Furthermore, the spring element generates a holding torque, so that rotation of the bearing assembly is prevented in the drive-less state. The spring element may be formed for example by a corrugated spring, by a plate spring or by a plurality of small helical compression springs. The spring element can also be designed in one piece with the first bearing ring and / or the oscillating element.

The vibrating element is preferably formed by a piezoelectric element for generating ultrasound. Such piezoelectric elements are established for use in ultrasonic drives and optimized in terms of their material. For this purpose, suitable electronic control units are available with which the vibration behavior to achieve different speeds of the drive can be controlled.

The friction element is preferably annular, so that it extends over the entire outer or inner circumference of the second bearing ring. This ensures a very uniform rotation drive. In a preferred embodiment of the storage arrangement, the first bearing ring is formed by a bearing outer ring, while the second bearing ring is formed by a bearing inner ring. The machine element to be stored and driven is received by the bearing inner ring and rotates, for example, in a machine frame in which the bearing outer ring is fastened.

Preferably, the bearing assembly is designed as a rolling bearing with rotating rolling elements. In particular, rolling bearings are suitable, which can absorb the axially acting forces without play. This is for example given in four-point ball bearings and tapered roller bearings with strained tapered rollers.

A storage arrangement according to the invention is characterized in that the elements forming the vibration drive are arranged in the annular cavity. This cavity can be created in different ways. Preferably, the annular cavity is formed within a spacer sleeve which is fixed to an end face of a bearing outer ring. The spacer sleeve preferably has the same outside diameter as the bearing outer ring and thus forms an axial extension of a conventional bearing. Since the spacer sleeve has a thinner wall than a typical bearing outer ring, a sufficiently large cavity is formed. The spacer sleeve simultaneously provides protection of the cavity, in particular during installation of the storage arrangement, but also against radially acting on the bearing assembly forces and foreign bodies. The bearing inner ring also extends in this embodiment over the axial length of the spacer sleeve, so that there the friction element can be attached as a rotor. The end face of the bearing outer ring, to which the spacer sleeve is attached, provides sufficient surface for the rotationally fixed arrangement of the vibrating element and the spring element. In other embodiments of a storage arrangement according to the invention, the annular cavity can also by circulating Recesses may be formed on the bearing inner ring or on the bearing outer ring. However, the cavity can also be formed by the cavity present next to the rolling elements. The cavity does not necessarily have to be spatially limited by a spacer sleeve or similar elements. The elements forming the vibration drive can also be attached laterally to an end face of an existing bearing, without these elements being enclosed by boundaries on all sides of the cavity. According to the invention, the annular cavity does not extend beyond the area between the inner and outer circumference of the bearing arrangement, so that the bearing arrangement can be used like a typical bearing in machines, vehicles, etc.

Preferably, an annular oscillating element and an annular friction element are in operative contact in an annular area. This circular contact surface of the vibrating element and the friction element is preferably inclined relative to the axis of the bearing arrangement, for example at an angle of 45 °. As a result, the available volume in the cavity can be effectively used to form the largest possible contact surface. A large contact surface ensures the transmission of high torques. However, the contact surface can also be aligned parallel or perpendicular to the axis of the bearing arrangement. The contact surface of the friction element has a large coefficient of friction. This can be achieved for example by a suitable coating or by a surface treatment of the friction element. On the contact surface but also many small support elements can be arranged, which drive the friction due to the vibrations of the vibrating element. The skilled person is known from the prior art various solutions for the design of the transition from the vibrating element to a driven element of a vibratory drive. The oscillating element may also be designed so that it extends over a plurality of spaced-apart sections or even only over a small portion of the friction element and is in operative contact therewith. Alternatively, the oscillating element may be annular, while the friction element extends only over portions of this ring. Insofar as the actuator should not allow complete rotation, the oscillating element and the friction element need not have a complete ring shape.

Further advantages, details and developments of the invention will become apparent from the following description of a preferred embodiment, with reference to the drawing.

The sole Fig. 1 shows a sectional view of a detail of a preferred embodiment of a storage arrangement according to the invention. The storage arrangement comprises a bearing outer ring 01 and a bearing inner ring 02 which are rotatable relative to each other. Between the bearing outer ring 01 and the bearing inner ring 02 balls 03 are arranged as rolling elements. The bearing arrangement forms a so-called four-point ball bearing, in which the balls are guided between each two circumferential flanks in the running surfaces of the bearing rings. Such a four-point ball bearing has only a slight axial play. The bearing inner ring 02 serves to receive a rotatable and driven machine element, such as a shaft. The storage arrangement is intended for mounting in a machine or a vehicle. For this purpose, the bearing outer ring 01 is attached to the machine or to the vehicle.

The bearing outer ring 01 is extended at one of its two end faces by a spacer sleeve 04 in the axial direction. In modified embodiments bearing outer ring and spacer sleeve could also be made in one piece. The outer diameter of the spacer sleeve 04 is similar to the outer diameter of the bearing outer ring 01. Consequently, the Lagerungsan- order is carried out in terms of their outer boundary as a conventional bearing, which is extended only in its axial extent. Such a bearing assembly can replace an existing bearing in many applications.

The bearing inner ring 02 extends axially over the entire length, which is formed by the bearing outer ring 01 and the spacer sleeve 04 extending it. Between the spacer sleeve 04 and the bearing inner ring 02 thus results in an annular cavity 06 in the form of a hollow cylinder. The radially outer boundary of the cavity 06 is formed by the inside of the spacer sleeve 04. The radially inner boundary of the cavity 06 is formed by the bearing inner ring 02, which is extended in the axial section of the spacer sleeve 04 compared to conventional bearings. Between the cavity 06 and the region of the storage arrangement in which the balls rotate 03, a seal 07 is arranged. The seal 07 ensures that a lubricant for lubricating the balls 03 can not get into the annular cavity 06. The seal is designed in the form of a sealing ring, in which a sealing lip bears against the rotating bearing inner ring. At the outer end face of the cavity 06 this is not closed. An open design of this type is suitable for storage arrangements in which it is ensured by their intended use that no foreign bodies, such as lubricants or chips can get into the cavity 06. If this is not ensured, the storage arrangement is to be designed so that the annular cavity is completely closed. In principle, the design of the cavity is adapted to the intended use of the storage arrangement. In particular, their arrangement in the machine is taken into account. Thus, for example, can be dispensed with the spacer sleeve, if its function is ensured by the installation arrangement of the storage arrangement. On the bearing inner ring 02, an annular friction element 08 is attached. The friction element 08 is arranged within the cavity 06 and rotates together with the bearing inner ring 02. The friction action required for the function has the friction element 08 only within a contact surface 09. The friction element 08 is made of steel or another material that is suitable to be able to absorb the torques occurring, wherein the contact surface 09 should have a high coefficient of friction, for example by a coating.

At the end face of the bearing outer ring 01 carrying the spacer sleeve, an annular oscillating element 11 in the form of a piezoelectric element is arranged, which forms the stator of the oscillating drive. The oscillating element 11 is non-rotatably connected to the bearing outer ring 01 in that guide lugs (not shown) of the oscillating element 11 are guided in guide recesses of the spacer sleeve 04 and thus prevent rotation of the oscillating element 11 relative to the bearing outer ring 01. Between the oscillating element 11 and the end face of the bearing outer ring 01, an annular spring 12 or a comparable spring element is arranged whose spring force presses the oscillating element 11 in the direction of the friction element 08 and thus ensures the effective contact between the friction element 08 and the oscillating element 11 in the contact surface 09 , The annular wave spring 12 may also be connected to the oscillating element 11 and the bearing outer ring 01 so that in this way the rotationally fixed arrangement of the vibrating element 11 is ensured with respect to the bearing outer ring 01.

The piezoelectric vibrating element 11 is electrically connected to an electronic driving unit (not shown). The drive unit can be attached directly to the storage arrangement or at a suitable position on the machine or on the vehicle. The drive unit comprises power electronic circuits, with which the piezoelectric vibrating element 11 can be set in Uitraschallschwingungen. In this case, the amplitude and the frequency of the drive voltage can be changed, wherein the piezoelectric vibrating element 11 is preferably operated in its resonant frequency. The electrical connection lines (not shown) are guided through an opening in the spacer sleeve 04 to the piezoelectric oscillating element 11.

LIST OF REFERENCE NUMBERS

01 bearing outer ring

02 bearing inner ring

03 balls

04 spacer sleeve

05 -

06 annular cavity

07 seal

08 friction element

09 contact area

10 -

11 oscillating element

12 annular wave spring

Claims

claims

A storage arrangement for supporting and driving a rotating machine element, comprising:

- A first bearing ring (01) and a second rotatable to this

Bearing ring (02), wherein the second bearing ring (02) receives the rotating machine element, and wherein between the by the bearing rings (01, 02) formed inner circumference of the bearing assembly and by the bearing rings (01, 02) formed outer circumference of the bearing assembly a annular cavity (06) is formed;

- A friction element (08) in the annular cavity (06) which is non-rotatably connected to the one of the two bearing rings (01, 02) is connected; and

- A vibrating element (11) in the annular cavity (06) which is non-rotatably connected to the other of the two bearing rings (02, 01) and in operative contact (09) with the friction element (08).

2. Storage arrangement according to claim 1, characterized in that the friction element (08) rotatably connected to the second machine element coupled to the rotating machine element bearing ring (02), and that the vibrating element (11) rotatably connected to the first, frame-fixed bearing ring ( 01) is connected.

3. Storage arrangement according to claim 2, characterized in that the storage arrangement further comprises a spring element (12) which is arranged between the oscillating element (11) and the first bearing ring (01) and its spring force on the oscillating element

(11) in the direction of the active contact (09) with the friction element (08) is aligned.

4. Storage arrangement according to one of claims 1 to 3, characterized in that the oscillating element is formed by a piezoelectric element (11) for generating ultrasonic vibrations, which is excited by an electronic drive unit to vibrate.

5. Storage arrangement according to one of claims 1 to 4, characterized in that the friction element (08) is annular.

6. Storage arrangement according to one of claims 1 to 5, characterized in that between the bearing rings (01, 02) rolling elements (03) are arranged.

7. Storage arrangement according to claim 6, characterized in that the rolling elements are formed by balls (03) and the Lagerungsan- order is designed as a four-point ball bearing.

8. Storage arrangement according to claim 6, characterized in that the rolling elements are formed by tapered rollers, which are braced within the bearing rings (01, 02).

9. Storage arrangement according to one of claims 1 to 8, characterized αe- indicates that the first bearing ring by a bearing outer ring

(01) is formed and the second bearing ring by a bearing inner ring

(02) is formed.

10. Storage arrangement according to claim 9, characterized in that the annular cavity (06) within a spacer sleeve (04) is formed, which is arranged on an end face of the bearing outer ring (01) and extends it axially, wherein the bearing inner ring (02) extends over the axial length of the bearing outer ring (01) and the spacer sleeve (04).

11. Storage arrangement according to claim 10, characterized in that the oscillating element (11) is annular and on which the

Distance sleeve (04) bearing end face of the bearing outer ring (01) is arranged.

12. Storage arrangement according to claim 10 or 11, characterized in that the friction element (08) is fixed to the se within the Distanzhül- (04) axially extending part of the bearing inner ring (02).

13. Storage arrangement according to one of claims 10 to 12, characterized in that the operative contact between the friction element (08) and the oscillating element (11) forming the contact surface (09) is aligned obliquely relative to the axis of the bearing assembly.

14. Storage arrangement according to one of claims 1 to 13, characterized in that the cavity (06) relative to the running surfaces of the bearing rings (01, 02) is sealed with a seal (07).

15. A storage arrangement according to claim 3 or a claim on this rückbe- retracted, characterized in that the spring element by an annular wave spring (12) is formed.