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 spring and/or damping 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 the spring and/or damping element is a ring element with a general hollow-cylindrical base body, wherein at least one spring part is arranged at the base body, wherein the spring part is formed by the material of the ring element and is formed by a section of the ring element which is cut out of the ring element is bend radially outwards or inwards from the hollow-cylindrical geometry of the base body.

Preferably, the mentioned spring and/or damping element is arranged between the outer ring of the bearing and the housing element.

The ring element can exert a radial spring force between the bearing ring and the housing element and/or the rotor element in the mounted state of the machine arrangement.

Preferably, a plurality of spring parts are arranged along the circumference of the ring element, preferably between 3 and 6 spring parts, which are preferably arranged equidistantly around the circumference of the ring element.

The at least one spring part has preferably a substantial strip-like shape. It can be formed by a punched section of the ring element. Preferably, it has a constant axial width along its circumferential extension. The ring element is preferably made from steel, especially from spring steel.

The stiffness of the at least one spring part (measured in N/mm) in radial direction is preferably smaller than the radial stiffness of the bearing. Specifically, the stiffness of the at least one spring part in radial direction can be at a maximum 25 % of the radial stiffness of the bearing.

The ring element and its at least one spring part have - according to a preferred embodiment of the invention - conduit means for piping a fluid from a fluid source into the free end section of the at least one spring part. By doing so a damping effect can be created. The conduit means can be established by at least one groove which is machined into the ring element and in its at least one spring part which runs in circumferential direction of the ring element and the at least one spring part respectively. The groove is preferably arranged at the outer circumference of the spring and/or damping element and its at least one spring part respectively.

With respect to the kind of fluid which can be employed it can be said that oil is preferred, but also grease, foam, wax and a visco-elastic material can be used.

Alternatively, the ring element and the at least one spring part can have at least one groove which is machined into the outer circumference and/or into the inner circumference of the spring and/or damping element and its at least one spring part respectively, wherein an elastic element, preferably an O-ring made from rubber or elastomere material, is inserted into at least a section of the groove. Also, only a part of an O-ring can be inserted into the groove.

Thus, an alternative solution contemplates that the mentioned groove in the ring element is not used for piping a fluid but for inserting a damping element into the groove which then runs in circumferential direction around at least a section of the circumference of the ring element. With respect to this damping element an O-ring which is solid or which is hollow and which is made from a rubber or an elastomere material is preferred.

The spring and/or damping element has preferably substantial the same axial extension as the bearing ring which is in contact with the spring and/or damping element. Preferably, the ring element contacts the reception of the housing element or the outer circumference of the outer ring and leaves a radial clearance to the outer circumference of the outer ring or the reception of the housing element. Also it can be provided that the ring element contacts the rotor element or the inner circumference of the inner ring and leaves a radial clearance to the inner circumference of the inner ring or the rotor element.

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 is mounted on the outer diameter of the roller bearing which has spring parts which are made from the material of a ring element; the spring parts provide a predefined stiffness to the roller bearing supported rotor on an electrical machine. When a fluid, preferably oil, is supplied to the spring parts a damping mechanism is created that reduces the vibration amplitudes in the system.

The spring part support is very compact due to the described design and provides specifically in combination with a fluid, preferably with oil, stiffness and damping at the same time with well-defined tunable parameters. That is, a very compact elastic radial spring 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; in addition with the supply of the fluid (oil) the flexible elements 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,

Fig. 2 shows a perspective sectional view of the bearing with a spring and/or damping element,

Fig. 3 shows a perspective view of the spring and/or damping element according to Fig. 1 and Fig. 2 and

Fig. 4 shows a perspective view of a spring and/or damping element according to an alternative embodiment of the invention.

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 spring and/or damping element 8 is arranged between the outer circumference 9 of the outer ring 6 and the reception 7 of the housing element 2. This spring and/or damping element 8 is basically a ring element which has a base body 10 with a hollow-cylindrical shape. Strip-like parts are punched out of the material of the ring element 8 and are bent radially inwardly; those strip-like parts are spring parts 11 which can be seen from Fig. 1 to Fig. 3. The spring parts 1 1 are thus tongue-like and leave the basic geometry, i. e. the hollow-cylindrical form, of the base body 10 to the radial inner direction. As can be seen from Fig. 3, four spring parts 11 are arranged equidistantly distributed along the circumference of the ring element 8.

As it is illustrated in Fig. 1, the spring parts 11 are designed to exert a spring force F in radial direction r between the outer ring 6 and the housing element 2 when the machine arrangement 1 is - as shown in Fig. 1 - in the mounted state.

As can be seen specifically from Fig. 1 , the base body 10 of the ring element 8 is located in such a manner that it contacts (preferably with press fit) the reception 7 (bore) of the housing element 2, i. e. the outer circumference of the ring element 14 of the ring element 8 contacts the bore surface in the housing element 2. However, the inner circumference 15 of the base body 10 of the ring element 8 is distanced by a radial clearance s (e. g. between 0.1 mm and 0.5 mm) from the outer circumference 9 of the outer ring 6. By this design it is made sure that (only) the spring parts 11 transmit the radial forces from the outer ring 6 to the housing element 2.

A further additional aspect of the present invention is shown in Fig. 1 to Fig. 3. Here it can be seen that conduit means 12 - being a groove - are machined into the outer circumference 14 of the ring element 8. The groove 12 is fluidically connected with a fluid source 13 (preferably with an oil source) which is shown only schematically in Fig. 2.

Thus, a fluid can be piped from the fluid source 13 via the groove 12 into the free end region of the spring parts 11. By doing so, the damping property of the system can be influenced beneficially.

As can be seen from Fig. 1 to Fig. 3, the tongue-like spring parts 1 1 are formed from a center part of the ring element 8. The spring parts 11 have a width in axial direction a of about 40 % to 80 % of the whole width of the ring element 8 in axial direction.

An alternative is depicted in Fig. 4. Here, the spring parts 11 are again machined out of the ring element 8 by punching, wherein now one of the lateral regions of the ring element 8 is used for producing the spring parts 11. Also here, four spring parts 11 are made from the ring element 8, i. e. adjoin to the base body 10. Reference Numerals:

Machine arrangement

Housing element

Rotor element

Bearing

Inner ring

Outer ring

Reception

Spring and/or damping element (ring element)

Outer circumference of the outer ring

Base body- Spring part

Conduit means (groove)

Fluid source (oil source)

Outer circumference of the spring and/or damping element Inner circumference of the spring and/or damping element

Radial direction

Axial direction

Spring force

Radial clearance