Patent Description:
In many electromechanical systems, there is a need for a hermetic encapsulation of an electric machine and a rotating apparatus, e.g. a turbo-compressor, connected to the electric machine. In a typical mechanical arrangement, a shaft of the electric machine is connected to a shaft of the rotating apparatus and a bushing of the shaft of the electric machine is sealed with respect to a casing of the electric machine and correspondingly a bushing of the shaft of the rotating apparatus is sealed with respect to a casing of the rotating apparatus. In many cases, there can be however challenges in sealing a rotating shaft with respect to a stationary casing.

In another mechanical arrangement, the electric machine and the rotating apparatus constitute an integrated device which is encapsulated with a common hermetic casing. For example, publication <CIT> describes an electrical turbo compressor suitable for supplying air to a fuel cell. The turbo compressor comprises a housing, a shaft which has a first end and a second end and is rotatably mounted relative to the housing, an electric machine arranged in the housing, and a turbo-compressor impeller and diffuser arranged in the housing, wherein the shaft can be driven by means of the electric machine. An inherent drawback of a mechanical arrangement of the kind mentioned above is that the integrated device comprising the electric machine and the rotating apparatus is a single entity which must typically be obtained from a single vendor and thereby the electric machine and the rotating apparatus must be obtained from the same vendor. Thus, it is challenging to achieve a same level of cost effectiveness than in a case in which the vendors of the electric machine and the rotating apparatus can be selected freely.

Publication <CIT> describes a connector system for connecting a first component and a second component of an industrial compression system. The connector system comprises a connector spool having a substantially cylindrical shape. The spool comprises an axial end and a flange at the axial end, the flange defining a radial surface for positioning proximate the first component. A spacer is positioned between the flange of the spool and the first component, the spacer including radial surfaces for providing uniform compressive force transmission between the spool and the first component.

Publication <CIT> describes a refrigeration compressor coupling protective cover. The refrigeration compressor coupling protective cover comprises a first sealing O-ring, a refrigeration compressor, a metal expansion joint, a protective cover upper cover, a protective cover lower cover, an acceleration gear box, a second sealing O-ring, dowel pins, and a third sealing O-ring. The first sealing O-ring is arranged between the metal expansion joint and the refrigeration compressor, the protective cover upper cover is arranged at the upper end of the protective cover lower cover, the third sealing O-ring is arranged between the metal expansion joint and the protective cover upper cover as well as the protective cover lower cover, the second sealing O-ring is arranged between the protective cover upper cover as well as the protective cover lower cover and the acceleration gear box, and the dowel pins are arranged in pin holes at the upper ends of extension circles of the front and back edge sides of the protective cover upper cover and the protective cover lower cover.

Publication <CIT> describes a centrifugal compressor unit that comprises a motor having a rotor, at least one compressor having a shaft driven by the rotor, and a set of bladed wheels fitted on the driven shaft. The motor and the compressor are mounted in a common watertight casing. The centrifugal compressor unit further comprises cooling means for cooling the motor. The cooling means have a gas cooler outside the casing. In operation, the motor, the compressor, and the casing having the motor and the compressor are arranged horizontally. Only one axial thrust bearing is provided on a compressor side.

The following presents a simplified summary in order to provide a basic understanding of some aspects of various invention embodiments.

In this document, the word "geometric" when used as a prefix means a geometric concept that is not necessarily a part of any physical object. The geometric concept can be for example a geometric point, a straight or curved geometric line, a geometric plane, a non-planar geometric surface, a geometric space, or any other geometric entity that is zero, one, two, or three dimensional.

In accordance with the present invention, there is provided a new electromechanical system that comprises:.

As the first and second hermetic joints are formed between the tubular portion, the electric machine, and the rotating apparatus, the electric machine, the joint element, and the rotating apparatus can be arranged to constitute a hermetically sealed entity, even if the electric machine and the rotating apparatus may be obtained as separate devices from different vendors.

Various exemplifying and non-limiting embodiments are described in accompanied dependent claims.

Various exemplifying and non-limiting embodiments both as to constructions and to methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplifying embodiments when read in conjunction with the accompanying drawings.

The features recited in the accompanied dependent claims are mutually freely combinable unless otherwise explicitly stated.

Exemplifying and non-limiting embodiments and their advantages are explained in greater detail below in the sense of examples and with reference to the accompanying drawings, in which:.

The specific examples provided in the description below should not be construed as limiting the scope and/or the applicability of the accompanied claims. Lists and groups of examples provided in the description are not exhaustive unless otherwise explicitly stated.

<FIG> shows a section view of an electromechanical system according to an exemplifying and non-limiting embodiment. The section is taken along a geometric section plane which is parallel with the yz-plane of a coordinate system <NUM>. The electromechanical system comprises an electric machine <NUM>, a rotating apparatus <NUM>, and a joint element <NUM> according to an exemplifying and non-limiting embodiment. The joint element <NUM> is configured to mechanically connect the electric machine <NUM> to the rotating apparatus <NUM>. In the exemplifying electromechanical system illustrated in <FIG>, the rotating apparatus <NUM> is a two-stage turbo-compressor where a first compressor stage and a second compressor stage are connected in series, and the electric machine <NUM> is an inner rotor induction machine whose rotor <NUM> comprises a cage winding. In this exemplifying case, the rotor <NUM> comprises a rotor core structure made of electrically insulated ferromagnetic sheets stacked in the axial direction of the electric machine <NUM>, i.e. in the z-direction of the coordinate system <NUM>. A stator <NUM> of the electric machine <NUM> comprises a stator core structure <NUM> constituted by a stack of electrically insulated ferromagnetic sheets stacked on each other in the axial direction of the electric machine. The stator <NUM> comprises stator windings whose coil sides are located in stator slots between stator teeth of the stator core structure <NUM>. The stator windings can be configured to constitute a multiphase winding for producing a rotating magnetic field when supplied with multiphase alternating electric currents. The multiphase winding can be e.g. a three-phase winding. In <FIG>, a section view of an end-winding of the stator windings is denoted with a reference <NUM>. The coil sides of the stator windings are not shown. The stator slots can be parallel with the axial direction of the electric machine <NUM>. It is however also possible that the stator <NUM> has skewed stator slots. It is to be noted that the above-described induction machine is an example only, and the electric machine can as well be another kind of electric machine such as e.g. an electrically magnetized synchronous machine, a permanent magnet synchronous machine, a synchronous reluctance machine, a switched reluctance machine, or a direct current machine.

In the exemplifying electromechanical system illustrated in <FIG>, the rotor <NUM> of the electric machine <NUM> is cooled so that the electromechanical system comprises a piping <NUM> configured to guide a part of an input flow of the turbo-compressor to flow through an airgap of the electric machine <NUM>. In <FIG>, the total input flow of the turbo-compressor is denoted with a reference <NUM>. The stator <NUM> of the electric machine <NUM> can be cooled for example with a water jacket in a stator frame <NUM>. The water jacket is not shown in <FIG>. It is also possible that the stator windings comprise hollow, tubular conductors and liquid or gaseous cooling fluid is circulated via the hollow conductors.

The joint element <NUM> comprises a coupling element <NUM> for connecting a shaft <NUM> of the electric machine <NUM> to a shaft <NUM> of the rotating apparatus <NUM> in a torque transferring way. The coupling element <NUM> can be e.g. a suitable coupling element according to the prior art. The coupling element <NUM> can be e.g. cambered to allow certain misalignment between the rotational axes of the shaft <NUM> of the electric machine <NUM> and the shaft <NUM> of the rotating apparatus <NUM>. Thus, the coupling element <NUM> can be arranged to remove the additional loading which would be otherwise caused by the possible misalignment to the bearings of the electric machine <NUM> and to the bearings of rotating apparatus <NUM>.

The joint element <NUM> comprises a tubular portion <NUM> that surrounds the coupling element <NUM>. A first rim of the tubular portion comprises a seal <NUM> for arranging a first hermetic joint between the first rim of the tubular portion <NUM> and an outer surface of the electric machine <NUM>. Correspondingly, a second rim of the tubular portion <NUM> comprises a seal <NUM> for arranging a second hermetic joint between the second rim of the tubular portion and an outer surface of the rotating apparatus <NUM>.

The tubular portion <NUM> comprises an opening <NUM> and a lid <NUM> for hermetically closing the opening. The opening <NUM> provides access to the coupling element <NUM> from outside the tubular portion <NUM>, e.g. to allow installation of the coupling element <NUM>. As the above-mentioned first and second hermetic joints are formed between the tubular portion <NUM>, the electric machine <NUM>, and the rotating apparatus <NUM>, the electric machine, the joint element, and the rotating apparatus constitute a hermetically sealed entity.

<FIG> shows a section view of an electromechanical system according to an exemplifying and non-limiting embodiment. The section is taken along a geometric section plane which is parallel with the yz-plane of a coordinate system <NUM>. The electromechanical system comprises an electric machine <NUM>, a rotating apparatus <NUM>, and a joint element <NUM> according to an exemplifying and non-limiting embodiment. The joint element <NUM> is configured to mechanically connect the electric machine <NUM> to the rotating apparatus <NUM>. In the exemplifying electromechanical system illustrated in <FIG>, the rotating apparatus <NUM> is a two-stage turbo-compressor where a first compressor stage and a second compressor stage are connected in series, and the electric machine <NUM> is an inner rotor permanent magnet machine whose rotor <NUM> comprises permanent magnets. The rotor <NUM> comprises a rotor core structure that can be made of for example electrically insulated ferromagnetic sheets stacked in the axial direction of the electric machine <NUM>, i.e. in the z-direction of the coordinate system <NUM>. As another exemplifying alternative, the rotor core structure may comprise ferrite or iron powder composites such as e.g. Soft Magnetic Composite SOMALOY®. In this exemplifying electromechanical system, the electric machine <NUM> comprises surface mounted permanent magnets attached on a surface of the rotor core structure. It is also possible that a rotor has buried permanent magnets located in cavities of a rotor core structure.

A stator <NUM> of the electric machine <NUM> comprises a stator core structure <NUM> constituted by a stack of electrically insulated ferromagnetic sheets stacked on each other in the axial direction of the electric machine. The stator <NUM> comprises stator windings whose coil sides are located in stator slots between stator teeth of the stator core structure <NUM>. The stator windings can be configured to constitute a multiphase winding for producing a rotating magnetic field when supplied with multiphase alternating electric currents. The multiphase winding can be e.g. a three-phase winding. In <FIG>, a section view of an end-winding of the stator windings is denoted with a reference <NUM>. The coil sides of the stator windings are not shown. The stator slots can be parallel with the axial direction of the electric machine <NUM>. It is however also possible that the stator <NUM> has skewed stator slots.

The joint element <NUM> comprises a coupling element <NUM> for connecting a shaft <NUM> of the electric machine <NUM> to a shaft <NUM> of the rotating apparatus <NUM> in a torque transferring way. In this exemplifying case, the coupling element <NUM> is a flexible coupling element to inhibit conduction of vibrations between the shafts <NUM> and <NUM> of the electric machine <NUM> and the rotating apparatus <NUM>. The flexible coupling element <NUM> can be for example a bellow coupling or some other suitable flexible coupling element.

The joint element <NUM> comprises a tubular portion <NUM> that surrounds the coupling element <NUM>. A first rim of the tubular portion comprises a seal <NUM> for arranging a first hermetic joint between the first rim of the tubular portion <NUM> and an outer surface of the electric machine <NUM>. Correspondingly, a second rim of the tubular portion <NUM> comprises a seal <NUM> for arranging a second hermetic joint between the second rim of the tubular portion and an outer surface of the rotating apparatus <NUM>. The tubular portion <NUM> comprises an opening <NUM> and a lid <NUM> for hermetically closing the opening. The opening provides access to the coupling element <NUM> from outside the tubular portion <NUM>, e.g. to allow installation of the coupling element <NUM>.

In the exemplifying electromechanical system illustrated in <FIG>, the tubular portion is provided with ring-shaped flexible elements <NUM> and <NUM> to inhibit conduction of vibrations between a stator frame <NUM> of the electric machine <NUM> and a frame <NUM> of the rotating apparatus <NUM>. In this exemplifying case, each of the ring-shaped flexible elements <NUM> and <NUM> is a ring-shaped metal bellow.

In the exemplifying electromechanical system illustrated in <FIG>, the rotor of the electric machine <NUM> is cooled so that the electromechanical system comprises a piping <NUM> configured to guide a part of an input flow of the turbo-compressor to flow through an airgap of the electric machine <NUM>. In <FIG>, the total input flow of the turbo-compressor is denoted with a reference <NUM>. The stator <NUM> of the electric machine <NUM> can be cooled for example with a water jacket in the stator frame <NUM>. The water jacket is not shown in <FIG>. It is also possible that the stator windings comprise hollow, tubular conductors and cooling fluid is circulated via the hollow conductors.

Claim 1:
An electromechanical system comprising:
- an electric machine (<NUM>, <NUM>),
- a rotating apparatus (<NUM>, <NUM>) being a turbo-compressor, and
- a joint element (<NUM>, <NUM>) configured to mechanically connect the electric machine to the rotating apparatus,
wherein the joint element comprises:
- a coupling element (<NUM>, <NUM>) connecting a shaft of the electric machine to a shaft of the rotating apparatus in a torque transferring way, and
- a tubular portion (<NUM>, <NUM>) surrounding the coupling element,
wherein:
- a first rim of the tubular portion comprises a seal (<NUM>, <NUM>) for arranging a first hermetic joint between the first rim of the tubular portion and an outer surface of the electric machine,
- a second rim of the tubular portion comprises a seal (<NUM>, <NUM>) for arranging a second hermetic joint between the second rim of the tubular portion and an outer surface of the rotating apparatus, and
- the tubular portion comprises an opening (<NUM>, <NUM>) and a lid (<NUM>, <NUM>) for hermetically closing the opening, the opening providing access to the coupling element from outside the tubular portion.
characterized in that the electromechanical system comprises a piping (<NUM>, <NUM>) configured to guide a part of an input flow of the turbo-compressor to flow through an airgap of the electric machine.