WO2014000798A1

WO2014000798A1 - Machine arrangement

Info

Publication number: WO2014000798A1
Application number: PCT/EP2012/062535
Authority: WO
Inventors: Jeroen Wensing; Nijs VAN DER MEI; Gilbert PETERS
Original assignee: Aktiebolaget Skf
Priority date: 2012-06-28
Filing date: 2012-06-28
Publication date: 2014-01-03

Abstract

The invention relates to a machine arrangement (1) comprising a housing element (2) and a rotor element (3), wherein the rotor element (3) is rotatable supported in the housing element (2) by at least one bearing (4), wherein the at least one bearing (4) has an inner ring (5) and an outer ring (6), wherein the housing element (2) has a reception (7) for the bearing (4). To improve the rotor dynamic behavior of a high speed machine the invention proposes that a ring element (8) is arranged between the outer circumference (9) of the outer ring (6) and the reception (7) of the housing element (2) and/or between the inner circumference of the inner ring (5) and the rotor element (3), wherein at least one cavity (10) is arranged in the inner of the ring element (8), wherein the cavity (10) is filled with a pressurized fluid (1 1) and wherein the cavity (10) has a fluidic connection (14) to the environment.

Description

Machine Arrangement

Technical Field

The invention relates to a machine arrangement comprising a housing element and a rotor element, wherein the rotor element is rotatable supported in the housing element by at least one bearing, wherein the at least one bearing has an inner ring and an outer ring, wherein the housing element has a reception for the bearing.

Background

Machine arrangements of this kind are well known in the art. They are employed for example in an electric machine like an electric compressor or a turbine generator. Here, a rotor is supported by bearings relatively to a housing.

In those machines the rotor is rotating during regular use. The rotor does not only maintain a certain constant revolution speed. Also, the rotary speed of the rotor varies. When starting the machine the rotor has to be driven from a revolution speed of zero to the required number of revolutions. Thus, the rotor will have to passage critical rotation frequencies where vibration will be excited. Due to the design of the machine is can be that during transition of critical frequencies, i. e. when the rotor passes a rotational speed which is a resonance frequency of the rotor system, vibrations reach critical magnitudes which can damage the machine arrangement and which at least cause loud noises.

It is known in the art to employ elastic O-rings or oil squeeze film dampers to improve the dynamical behavior of the arrangement when passing critical rotations speeds of the rotor.

Thus, it is an o bj e c t of the present invention to propose a machine arrangement which allows a silent and safe passage of critical frequencies. So, vibrations and noises should be reduced which can occur during operation of the machine arrangement.

Summary of the invention

A s o l u t i o n according to the invention is characterized in that a ring element is arranged between the outer circumference of the outer ring and the reception of the housing element and/or between the inner circumference of the inner ring and the rotor element, wherein at least one cavity is arranged in the inner of the ring element, wherein the cavity is filled with a pressurized fluid and wherein the cavity has a fluidic connection to the environment. Preferably, the mentioned ring element is arranged between the outer ring of the bearing and the housing element.

The pressurized fluid is preferably oil. Other suitable fluids are specifically grease, wax and visco-elastic material. The pressurized fluid can furthermore contain rubber particles to enlarge the damping ability of the fluid.

Also, the pressurized fluid can be foamed. The at least one cavity is preferably fluidically connected with a fluid source to ensure permanent and sufficient pressure in the cavity.

The fluidic connection is preferably formed by at least one small opening, preferably by at least one small gap, which is arranged in or at the ring element. The gap is preferably formed between two parts forming the ring element; alternatively, the gap is formed between the ring element and the housing element or rotor element.

With respect to the magnitude of the gap it has to be said that the gap should be not too big to keep sufficient fluid with a respective pressure in the cavity; on the other hand the gap should be big enough to establish a certain spring effect, i. e. under pressure fluid should be able to escape from the cavity. With regard to this demand it has been four beneficially, when the gap has a width between 10 μιη and 150 μιη, preferably between 20 μιη and 60 μιη.

The ring element can be made of steel, especially of spring steel.

The cavity is preferably ring shaped and extends along at least a part of the circumference of the ring element. An embodiment suggests that the cavity extends along the whole circumference of the ring element. Another embodiment proposes that more than one cavity is arranged in the ring element; preferably, each cavity extends along a part of the circumference of the ring element.

The ring element can have at least one incision which is directed in radial direction and which extends along a part of the radial thickness of the ring element. Preferably, at least two, preferably three to five, incisions are arranged around the circumference of the ring element, wherein the incisions are preferably arranged equidistantly around the circumference.

By the incisions, i. e. by the circumferential cuts, the stiffness of the ring element is reduced. The stiffness of the fluid filled ring element (measured in N/mm) in radial direction is preferably smaller than the radial stiffness of the bearing. Specifically, the stiffness of the fluid filled ring element in radial direction can be at a maximum 25 % of the radial stiffness of the bearing. The ring element can have at least one groove, preferably in its inner or outer circumference, wherein an elastic element is inserted into at least a section of the groove. With respect to this elastic element an O-ring which is solid or which is hollow and which is made of a rubber or an elastomere material is preferred.

The ring element can have substantial the same axial extension as the bearing ring which is in contact with the ring element. Alternatively, the ring element can have substantial the same axial extension as the outer ring of the bearing in the contact region with the bearing, wherein the axial extension of the ring element rises with growing distance from the outer ring. In this case it is preferred that the ring element has a trapezoid radial cross section.

The bearing is preferably a roller bearing.

The machine arrangement is preferably a part of an electrical machine, especially of an electric compressor or of a turbine generator.

Accordingly and preferably a metal ring element is mounted on the outer diameter of the roller bearing which has a cavity in it which cavity is filled with a pressurized fluid. By doing to the critical rotation frequencies of the rotor can be efficiently influenced.

The ring element is very compact due to the described design and provides stiffness and damping at the same time with well-defined tunable parameters. That is, a very compact elastic radial support is given to provide and tune the optimum rotor dynamic behavior of a high speed electrical machine like an electric compressor or a turbine generator. Due to the proposed fluid the ring element can also provide damping to the rotor system to allow a secure passage of critical frequencies and reduce noise and vibrations. Thus, a flexible damping support is established for a roller bearing system. Brief description of the drawings

The drawings show embodiments of the invention. Fig. 1 shows a radial cross section through a part of a machine arrangement which is an electrical machine according to a first embodiment of the invention,

Fig. 2 shows a radial cross section similar to Fig. 1 according to a second embodiment of the invention and

Fig. 3 shows a view in axial direction of a ring element of the machine arrangement.

Detailed description of the invention

In Fig. 1 a machine arrangement 1 is shown which is for example an electric compressor or turbine generator. A rotor element 3 is arranged in a housing element 2; the rotor element 3 rotates around an axis a. For supporting the rotor element 3 in the housing element 2 a bearing 4 is employed (a further bearing is not depicted which is necessary to support the rotor element 3). The bearing 4 has an inner ring 5 and an outer ring 6. The bearing 4 is a deep groove ball bearing and thus has radial and axial bearing properties.

The housing element 2 has a reception 7 for the bearing 4, i. e. a cylindrical bore. Essentially, a ring element 8 is arranged between the outer circumference 9 of the outer ring 6 and the reception 7 of the housing element. A cavity 10 is arranged in the inner of the ring element 8. The cavity 10 is filled with a pressurized fluid 11 , which is oil in the present embodiment. To keep the cavity under a desired pressure, the cavity 10 is fluidically connected with a fluid source (oil source) by which oil with a predetermined pressure is supplied into the cavity 10. To allow a certain spring ability of the ring element 8, a fluidic connection 14 is established in the ring element 8, i. e. a fluidic connection between the cavity 10 and the environment. Presently, this is achieved by a design of the ring element 8 which has two parts. At the transition zone of the two parts the gap 14 is established.

By doing so, the elastic and damping properties of the system can be influenced beneficially.

In Fig. 1 is can be seen that the cross section of the ring element 8 is substantial rectangular. That is, the width of the ring element 8 is constant in axial direction and basically the same than the width of the outer bearing ring 6.

In Fig. 2 an alternative is shown. Here, the ring element 8 has basically the same width than the outer bearing ring 6 in the region where the outer bearing ring 6 and the ring element 8 adjoin. Then, with growing diameter, i. e. seen in the radial outer direction r the width of the ring element 8 becomes bigger. Here, the cross section of the ring element 8 is substantially trapezoid. Also, the cavity 10 becomes bigger in its width correspondingly. Here, the ring element 8 adjoins with its outer circumference the reception bore 7 of the housing element 2. At the transition between the ring element 8 and the housing element 2 the fluidic connection 14 is established.

Preferably, the width of the gap 14 is between 20 μιη and 60 μιη to allow a certain drain of fluid from the cavity 10 but to keep a desired radial stiffness of the ring element 8. It is aimed that the pressure of the fluid has an expanding effect on the ring element 8 to effectively influence the location of critical frequencies of the rotor 3. This is quite difficult if the ring element 8 is too stable.

Thus, Fig. 3 shows a possibility how to reduce the stiffness of the ring element 8.

As can be seen in this figure, the ring element 8 has four incisions 13 which are distributed equidistantly around the circumference of the ring element 8. The incisions 13 start at the outer diameter of the ring element 8 and extend inwardly a certain distance. A rest of the ring is in fact not cut so that the ring element 8 remains a sufficient stability.

Four distinct cavities 10 can be formed in each section which is separated by two incisions 13. All cavities are fluidically connected with the fluid source 12 as schematically shown in Fig. 1.

While oil is a proper fluid which is employed to be pressed into the cavity 10, also other kinds of fluids can be taken into consideration. Examples are grease, wax and visco-elastic material. Also mixtures for two or more of the mentioned materials can be beneficial. Such a viscous fluid dissipates energy on shear and is proper to influence the location of critical frequencies of the rotor 3. Also, it is possible to combine the mentioned solution with O-rings made from a rubber material; those O-rings can be solid or hollow. By this design is becomes possible to supply the desired stiffness by the sheet metal ring element 10 and to create a certain damping ability by the elastomere or rubber O-ring.

The oil which leaves the cavity 10 via the gap 14 is suitable collected and reused.

Reference Numerals:

1 Machine arrangement

2 Housing element

3 Rotor element

4 Bearing

5 Inner ring

6 Outer ring

7 Reception

8 Ring element

9 Outer circumference of the outer ring

10 Cavity

11 Pressurized fluid

12 Fluid source

13 Incision

14 Fluidic connection (gap)

r Radial direction

a Axial direction

Claims

201200274 June 27th 2012 Patent Claims:

1. Machine arrangement (1) comprising a housing element (2) and a rotor element (3), wherein the rotor element (3) is rotatable supported in the housing element (2) by at least one bearing (4), wherein the at least one bearing (4) has an inner ring (5) and an outer ring (6), wherein the housing element (2) has a reception (7) for the bearing (4), characterized in that a ring element (8) is arranged between the outer circumference (9) of the outer ring (6) and the reception (7) of the housing element (2) and/or between the inner circumference of the inner ring (5) and the rotor element (3), wherein at least one cavity (10) is arranged in the inner of the ring element (8), wherein the cavity (10) is filled with a pressurized fluid (1 1) and wherein the cavity (10) has a fluidic connection (14) to the environment.

2. Machine arrangement according to claim 1 , characterized in that the pressurized fluid (11) is oil.

3. Machine arrangement according to claim 1 , characterized in that the pressurized fluid (11) is grease.

4. Machine arrangement according to claim 1 , characterized in that the pressurized fluid (1 1) is wax.

5. Machine arrangement according to claim 1 , characterized in that the pressurized fluid (11) is a visco-elastic material.

6. Machine arrangement according to one of claims 1 to 5, characterized in that the pressurized fluid (11) contains rubber particles.

7. Machine arrangement according to one of claims 1 to 6, characterized in that the pressurized fluid (11) is foamed.

8. Machine arrangement according to one of claims 1 to 7, characterized in that the at least one cavity (10) is fluidically connected with a fluid source (12).

9. Machine arrangement according to one of claims 1 to 8, characterized in that the fluidic connection (14) is formed by at least one small opening, preferably by at least one small gap, which is arranged in or at the ring element (8).

10. Machine arrangement according to claim 9, characterized in that the gap (14) is formed between two parts forming the ring element (8) or between the ring element and the housing element (2) or rotor element (3).

11. Machine arrangement according to claim 9 or 10, characterized in that the gap (14) has a width between 10 μιη and 150 μιη, preferably between 20 μιη and 60 μιη.

12. Machine arrangement according to one of claims 1 to 11 , characterized in that the ring element (8) is made of steel, especially of spring steel.

13. Machine arrangement according to one of claims 1 to 12, characterized in that the cavity (10) is ring shaped and extends along at least a part of the circumference of the ring element (8).

14. Machine arrangement according to claim 13, characterized in that the cavity (10) extends along the whole circumference of the ring element (8).

15. Machine arrangement according to claim 13, characterized in that more than one cavity (10) is arranged in the ring element (8), wherein each cavity (10) extends along a part of the circumference of the ring element (8).

Machine arrangement according to one of claims 1 to 15, characterized in that the ring element (8) has at least one incision (13) which is directed in radial direction (r) and which extends along a part of the radial thickness of the ring element (8).

Machine arrangement according to claim 16, characterized in that at least two, preferably three to five, incisions (13) are arranged around the circumference of the ring element (8), wherein the incisions (13) are preferably arranged equidistantly around the circumference.

Machine arrangement according to one of claims 1 to 17, characterized in that the stiffness of the fluid filled ring element (8) in radial direction (r) is smaller than the radial stiffness of the bearing (4), wherein the stiffness of the fluid filled ring element (8) in radial direction (r) is preferably at a maximum 25 % of the radial stiffness of the bearing (4).

Machine arrangement according to one of claims 1 to 18, characterized in that the ring element (8) has at least one groove, preferably in its inner or outer circumference, wherein an elastic element, preferably an O-ring made of rubber or elastomere material, is inserted into at least a section of the groove.

20. Machine arrangement according to one of claims 1 to 19, characterized in that the ring element (8) has substantial the same axial extension as the bearing ring (5, 6) which is in contact with the ring element (8).

21. Machine arrangement according to one of claims 1 to 19, characterized in that the ring element (8) has substantial the same axial extension as the outer ring (6) of the bearing (4) in the contact region with the bearing (4), wherein the axial extension of the ring element (8) rises with growing distance from the outer ring (6).

22. Machine arrangement according to claim 21 , characterized in that the ring element (8) has a trapezoid radial cross section.

23. Machine arrangement according to one of claims 1 to 22, characterized in that the bearing (4) is a roller bearing.

24. Machine arrangement according to one of claims 1 to 23, characterized in that the machine arrangement is a part of an electrical machine, especially of an electric compressor or of a turbine generator.