AU2012384006A1

AU2012384006A1 - Vibrational decoupling of the stator of an electric machine

Info

Publication number: AU2012384006A1
Application number: AU2012384006A
Authority: AU
Inventors: Christoph Balzer; Gunther Siegl
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2012-06-27
Filing date: 2012-06-27
Publication date: 2015-01-15
Also published as: CN104412492B; KR101926222B1; EP2845292B1; EP2845292A1; ES2704008T3; BR112014032642A2; CN104412492A; KR20150033672A; WO2014000789A1

Abstract

The invention relates to an electric machine comprising a housing (1) and a cylindrical stator (2). In order to improve the properties of said electric machine with regard to vibrations, it is suggested that the machine comprises at least one panel (3) which is secured in each case to the side of the cylindrical stator (2) that faces the housing (1), a gap (4) being formed in the radial direction between said housing (1) and the respective panel (3). At least one connecting element (5) is secured in each case to both a guide bush (7) of the housing (1) and to the at least one panel (3), and by means of which forces can be transmitted from the cylindrical stator (2) to said housing (1). At least one damping element (6) is arranged between the at least one connecting element (5) and the guide bush (7) in each case.

Description

PCT/EP2012/062468 / 2012P06540WO 1 Description Vibrational decoupling of the stator of an electric machine The invention relates to an electric machine comprising a housing and a cylindrical stator. In such electric machines, the stator is often welded into the machine housing, thereby allowing vibrations and solid-borne sound to be transmitted to the housing structure. If the machine housing is secured to a system, vibration dampers can be attached under the feet of the machine housing, such that the machine housing and the stator which is rigidly connected thereto are decoupled from the rest of the system. In order to decouple the stator from the machine housing, it is normal practice to suspend the stator core stack, e.g. on leaf springs or on special dampers within the machine housing. Consequently, there is no unsprung or undamped connection between the stator and the machine housing. For example, DE 196 33 421 Al discloses a ship drive system which has a drive motor comprising a stator and a rotor. The rotor is connected to a supporting chassis and is rotatably mounted, and the stator has feet which are connected to the supporting chassis via an elastic spring element in each case. The object of the invention is to improve the vibrational properties of an electric machine. The object is achieved by an electric machine of the type cited in the introduction, comprising at least one panel which is secured in each case to that side of the cylindrical stator PCT/EP2012/062468 / 2012P06540WO 2 facing the housing, a gap being disposed radially between the housing and the respective panel, at least one connecting element which is secured in each case to both the housing and the at least one panel and by means of which forces can be transmitted from the cylindrical stator to the housing, and at least one damping element which is arranged in each case between the at least one connecting element and the housing. The at least one panel is connected to the cylindrical stator and can absorb forces and therefore also vibrations of the stator. The gap between the housing and the at least one panel prevents vibrations of the stator from being passed directly to the housing. Instead, the forces of the stator are conducted via the at least one panel into the housing by means of the at least one connecting element, the vibrations and the solid-borne sound of the stator being damped by the at least one damping element. It is therefore possible effectively to suppress the unwanted transfer of vibrations and in particular solid-borne sound from the stator to the housing. By using the at least one panel, which is secured to the stator, forces can be effectively carried away from the stator. In particular, if the at least one panel is secured to the stator on a bearing surface area which is relatively small in comparison with the curved surface area of the cylindrical stator, a particularly good vibrational decoupling of the stator from the housing can be achieved. At the same time, the exposure of a major part of the stator surface allows particularly effective cooling of the stator via the gap between the housing and the stator. The decoupling of vibrations can be further improved if the surface area via which said vibrations are transmitted into PCT/EP2012/062468 / 2012P06540WO 3 the machine housing is as small as possible. This can be achieved by means of connecting elements which, relative to the curved surface area of the stator or the internal surface area of the housing, are comparatively small and/or few in number. By virtue of the simple structure according to the invention, the total number of elements required to secure the stator can be significantly reduced in comparison with known electric machines. The at least one connecting element can be welded onto the respective panel, for example, particularly if the at least one connecting element engages in the housing. In order to achieve this, the at least one panel is first secured to the stator and the stator is then introduced into the housing. Finally, the at least one connecting element is welded onto the respective panel. In an advantageous embodiment of the invention, the housing has at least one guide bush, through which the respective connecting element can be fed and by means of which the respective connecting element can be aligned. The at least one guide bush is connected to the housing and holds both the respective connecting element and the respective damping element. Forces of the stator are therefore conducted via the at least one panel, the respective connecting element, the respective damping element and finally via the at least one guide bush into the housing, vibrations and solid-borne sound of the stator being effectively damped by the respective damping element. By virtue of using guide bushes, it is moreover ensured that the connecting elements are comparatively small and therefore PCT/EP2012/062468 / 2012P06540WO 4 the surface area which transmits the vibrations between the stator and the housing is comparatively small, providing an effective decoupling of the stator. Particularly good vibrational isolation of the stator can be achieved by means of damping elements which are adapted to the guide bush and the connecting elements. The at least one guide bush allows the connecting element to be adjusted in both tangential and radial directions, and therefore the stator can be aligned within the housing when using a plurality of guide bushes. At the same time, it is particularly easy to secure the at least one connecting element in the at least one guide bush, this being necessary for economical automation of the manufacture of the electric machine. The at least one guide bush also offers the possibility of particularly simple repair to the electric machine, e.g. allowing the stator to be replaced with particular ease in the event of damage to the stator. If different panels and different connecting elements are used for different electric machines, a modular system of electric machines can be developed, said modular system allowing the installation of various stators on the basis of a specific housing size. The individual stators may differ in diameter or length, for example, yet nonetheless be installed in the same housing, thereby allowing particularly economical manufacture of electric machines. In a further advantageous embodiment of the invention, at least one of the guide bushes has a ridge, wherein said ridge incorporates a hole and the respective connecting element can be aligned by means of an aligning element which is introduced into this hole.

PCT/EP2012/062468 / 2012P06540WO 5 By virtue of the aligning element which is introduced into the holes, particularly strong forces can be exerted on the at least one guide bush, thereby allowing the at least one connecting element to be aligned even after assembly of the electric machine. The aligning element can be supported on the housing of the electric machine or on a reference point outside of the electric machine, for example, and consequently exert forces from the housing or the reference point onto the respective guide bush. In particular, the hole can be designed as a threaded hole and the connecting element as a screw which is screwed into said threaded hole, such that the respective guide bush can be aligned along the direction of the axis of the screw by means of rotating the screw. It is obviously also possible for a guide bush to have a plurality of holes, said holes pointing in different directions, such that the guide bush can be aligned along various directions. In a further advantageous embodiment of the invention, provision is made for at least two panels which are separated from each other in an axial direction in each case, and for at least one rib which runs in an axial direction and connects the at least two panels, wherein the respective rib engages in an opening of the respective panel in an axial direction, and wherein at least one of the connecting elements is secured to the respective rib in each case. The at least two panels each have an opening in an axial direction, e.g. in the form of a hole, wherein the at least two panels are connected by a rib which engages in the opening of the respective panel. By virtue of this arrangement, the PCT/EP2012/062468 / 2012P06540WO 6 stator can be connected to the housing by means of only very few connecting elements, thereby producing a particularly effective vibrational decoupling of the stator from the housing. In particular, the two panels can be connected together by means of a plurality of ribs, wherein each rib can be secured to the housing by means of a plurality of connecting elements in the case of particularly high mechanical stress. A plurality of pairs of panels is also possible, wherein each pair is connected by a rib in each case, and wherein the ribs run in an axial direction and are secured to the stator at various positions of the stator circumference. These panels can be connected in a circumferential direction by means of further circumferential securing elements, which also press the panels onto the stator. Each rib can again be secured to the housing by means of a plurality of connecting elements. In a further advantageous embodiment of the invention, two panels are arranged on either side of the axial center of the cylindrical stator and surround the cylindrical stator in circumferential direction in each case, wherein the curved surface area of the cylindrical stator is composed in geometric terms of two curved surface halves which are concentric relative to the rotational axis of the electric machine, and a rib is arranged in each case radially further out relative to the center of each of the curved surface halves, wherein two connecting elements are secured to the respective rib in each case. The two panels are secured to the stator, e.g. close to its two axial ends in each case, wherein the respective panel can be embodied in particular as a ring surrounding the PCT/EP2012/062468 / 2012P06540WO 7 cylindrical stator. The cylindrical stator can be notionally divided into two concentric curved surface halves, wherein two ribs which are diametrically opposed relative to the stator axis are connected to the respective panels via axial openings therein. The electric machine therefore has two ribs, which are connected to the housing by a total of four connecting elements. This achieves both stable suspension of the stator in the housing, said suspension being able to withstand even high mechanical stress, and good vibrational decoupling of the stator from the housing, such that vibrations and in particular solid-borne sound of the stator are isolated from the housing. In an alternative advantageous embodiment of the invention, two panels are arranged on either side of the axial center of the cylindrical stator and surround the cylindrical stator in circumferential direction in each case, wherein the curved surface area of the cylindrical stator is composed in geometric terms of four curved surface quarters which are concentric relative to the rotational axis of the electric machine, and a rib is arranged in each case radially further out relative to the center of each of the curved surface quarters, wherein two connecting elements are secured to the respective rib in each case. The electric machine has four ribs, pairs of which are diametrically opposed relative to the rotor axis, adjacent ribs being arranged every 90 in a circumferential direction. This allows particularly stable suspension of the stator in the housing, said suspension being able to withstand the highest mechanical stresses. Satisfactory vibrational PCT/EP2012/062468 / 2012P06540WO 8 decoupling of the stator from the housing is nonetheless guaranteed, since the stator can vibrate in all directions without the vibrations being transmitted to the housing. If the machine housing is cuboid, further advantage can be obtained from a favorable and economical use of space, i.e. by arranging the ribs and in particular the connecting elements in the four corners of the housing. Such a machine is comparatively compact while at the same time having beneficial vibrational properties. In a further advantageous embodiment of the invention, the respective connecting element is designed as a pin and engages in a recess of the respective rib, wherein the respective connecting element has a taper and the respective damping element rests on the axial surface of the taper. By virtue of its punctiform distribution over the surface area transmitting vibrations, the embodiment of the connecting element as a pin allows particularly effective vibrational decoupling of the stator from the housing. The pin is so embodied as to comprise a first region having a smaller diameter and a second region having a larger diameter, wherein the pin is installed e.g. such that the second region is arranged radially further in within the electric machine. This allows the respective damping element to rest on the pin at the transition point from the second to the first region, thereby allowing the respective damping element to absorb the vibrations in a radial direction relative to the cylindrical stator and damp them in a particularly effective manner. In addition to this, the pin and the respective damping element are also able to absorb and damp tangential forces and vibrations.

PCT/EP2012/062468 / 2012P06540WO 9 In a further advantageous embodiment of the invention, the respective connecting element is secured to the respective rib by means of a screw connection or a welded joint. As a result of securing the respective connecting element to the respective rib by means of a screw connection or a welded joint, assembly is particularly straightforward, particularly if the stator including attached panels and connecting elements has a larger dimension transversely relative to the stator axis than the internal measurement of the housing, e.g. if the connecting elements extend into the housing. The stator including attached panels and integrated rib can therefore be introduced into the housing first, and the respective connecting element then connected to the rib through the housing from the outside. This process can be automated particularly effectively, thereby allowing efficient manufacture of the electric machine. If the respective connecting element is fastened by means of a screw connection to the respective rib, the respective rib has a corresponding threaded hole at the respective position. In a further advantageous embodiment of the invention, at least one of the damping elements is embodied as an elastomer or an all-metal damper element. Both elastomers and all-metal damper elements have good properties in respect of vibration damping and are also available at low cost. Depending on the application, it may be advantageous that elastomers offer electrical insulation while all-metal damper elements are electrically conductive. The invention is described and explained in greater detail PCT/EP2012/062468 / 2012P06540WO 10 below with reference to the exemplary embodiments illustrated in the figures, in which: FIG 1 shows a schematic drawing of a first exemplary embodiment of the electric machine according to the invention, FIG 2 shows a schematic drawing of a second exemplary embodiment, FIG 3 shows an exemplary embodiment of a connecting element, and FIG 4 shows a further exemplary embodiment of a connecting element. FIG 1 shows a schematic drawing of a first exemplary embodiment of the electric machine according to the invention. The electric machine has a housing 1, in which is arranged a cylindrical stator 2 and a panel 3 that is secured to the stator 2. A gap 4 or hollow space remains between the panel 3 and the housing 1. The stator 2 is connected via the panel 3 to connecting elements 5 which are secured to the housing 1, damping elements 6 being arranged between the connecting elements 5 and the housing 1. The damping elements 6 damp vibrations and solid-borne sound, which would otherwise be transmitted from the stator 2 to the housing 1 via the panel 3 and the connecting elements 5, and consequently results in good vibrational decoupling of the stator 2 from the housing 1. Only by means of the connecting elements 5 are the panel 3 and the stator 2 indirectly in contact with the housing 1 via the damping elements 6, and therefore vibrations and solid-borne sound of the stator 2 cannot be transmitted to the housing 1.

PCT/EP2012/062468 / 2012P06540WO 11 In the context of the exemplary embodiment, two connecting elements 5 with the associated damping elements 6 are provided, being diametrically opposed. It is also conceivable to provide four or more connecting elements 5 with the associated damping elements 6, wherein pairs of the connecting elements 5 are diametrically opposed and wherein the individual pairs are arranged at different positions along the stator axis. According to the size and mass of the stator 2, and the mechanical load-bearing capacity of the connecting elements 5 and the damping elements 6, the chosen number of connecting elements 5 and associated damping elements 6 may be greater or smaller, in order to ensure both an adequately stable construction of the electric machine and the fewest possible connection points transmitting vibrations and solid borne sound between the stator 2 and the housing 1. FIG 2 shows a schematic drawing of a second exemplary embodiment. A cylindrical stator 2 is surrounded by a panel 3 which is secured by means of four connecting elements 5 to a cuboid housing 1, a gap 4 being present between the housing 1 and the panel 3. The connecting elements 5 are in each case connected to the housing 1 via damping elements 6 which damp vibrations and solid-borne sound. The four connecting elements 5 are so arranged as to be diametrically opposed in pairs, said connecting elements 5 being arranged every 90' in a circumferential direction around the cylindrical stator 2 in each case. This allows the stator 2 to be secured to the housing 1 in a manner which makes particularly economical use of space, because the connecting elements 5 are placed approximately in the four corners of the inside of the cuboid housing 1. This means that at least the shorter side length of a cuboid having a rectangular cross PCT/EP2012/062468 / 2012P06540WO 12 section can be so selected as to be only minimally greater than the diameter of the stator 2 including attached panel 3. Moreover, as suggested in the present exemplary embodiment, the securing via the two lower connecting elements 5 can take the form of two supporting feet, such that greater forces can be absorbed thereby than by the two upper connecting elements 5. This is particularly advantageous if the housing of the electric machine has a preferred installation location and a comparatively heavy stator 2. It is moreover conceivable for a plurality of groups of four connecting elements 5 and associated damping elements 6 to be used for connecting the stator 2 to the housing 1. In this case, each group of four connecting elements 5 and associated damping elements 6 is arranged at a different position along the stator axis. FIG 3 shows a section of a fourth exemplary embodiment. The electric machine has a housing 1, which is connected via a damping element 6 to a connecting element 5. In this case, the connecting element 5 is embodied as a pin and the damping element 6 as a damping ring which surrounds the pin in a circumferential direction. The damping element 6 damps vibrations and solid-borne sound and ensures good vibrational decoupling of the stator 2 from the housing 1. The connecting element 5 points radially inwards relative to the electric machine and projects into a panel 3 which surrounds a stator 2. A rib 10 is arranged in an axially disposed opening of the panel 3, wherein the connecting element 5 is fed through the rib 3 in a radial direction and connected to the rib 3. This connection can be embodied as a PCT/EP2012/062468 / 2012P06540WO 13 screw connection, for example, such that the rib 3 has a threaded hole and the connecting element 5 a matching thread. In this case, the rib 10 can function as a connection of the panel 3 to a further panel (not shown), wherein the two panels 3 are separated from each other by a clearance in an axial direction relative to the stator axis. Furthermore, a gap 4 is disposed between the panel 3 and the housing 1. FIG 4 shows a section of a third exemplary embodiment. The electric machine has a housing 1, a cylindrical stator 2 and a panel 3 which is secured to the stator 2. A gap 4 remains between the panel 3 and the housing 1. A rib 10 is arranged in the panel 3, specifically in an axially disposed opening of the panel 3, said opening being embodied as a continuous groove. In this case, the rib 10 can function as a connection of the panel 3 to a further panel (not shown), wherein the two panels 3 are separated from each other by a clearance in an axial direction relative to the stator axis. The rib 10 has a recess 11 into which a connecting element 5 projects, wherein said connecting element 5 passes outwards in a radial direction through the panel 3 and creates a connection of the rib 10 and hence the panel 3 and the stator 2 to the housing 1. The recess 11 can be embodied as a threaded hole, for example, into which the connecting element 5 can be screwed by virtue of a matching thread. Alternatively, it is also conceivable for the connecting element 5 to be connected to the rib 10 by means of a welded joint. In order to create the connection to the housing 1, the connecting element 5 is fed into a guide bush 7, wherein said PCT/EP2012/062468 / 2012P06540WO 14 guide bush 7 is secured in the housing 1 and wherein a damping element 6 is arranged between the connecting element 5 and the guide bush 7. The damping element 6 damps vibrations and solid-borne sound and ensures good vibrational decoupling of the stator 2 from the housing 1. The connecting element 5 has a taper 12 in this case, the tapered end of the connecting element 5 pointing radially outwards. In the context of the exemplary embodiment, the damping element 6 takes the form of a damping ring which is placed on the connecting element 5, being positioned radially inwards in the region of the taper 12, and surrounds the connecting element 5 circumferentially. The connecting element 5 can therefore transfer forces, in both radial and tangential directions relative to the stator axis of the electric machine, via the damping element 6 to the guide bush 7 and thus to the housing 1, vibrations and solid-borne sound being effectively suppressed by the damping element 6. The guide bush 7 has a ridge 8 which points radially outwards and incorporates a hole 9. An aligning element (not shown) can be introduced into the hole 9, and is supported e.g. on the housing 1 of the electric machine or on another reference point. The guide bush 7 can therefore be moved in a desired direction by means of the ridge 8 and the aligning element even after installation of the electric machine, whereby the connecting element 5 and consequently also the stator 2 of the electric machine can be aligned. In summary, the invention relates to an electric machine comprising a housing and a cylindrical stator. In order to improve the vibrational properties of an electric machine, it is proposed that the electric machine should feature at least PCT/EP2012/062468 / 2012P06540WO 15 one panel which is secured in each case to that side of the cylindrical stator facing the housing, a gap being disposed in a radial direction between the housing and the respective panel, at least one connecting element which is secured in each case to both the housing and the at least one panel and by means of which forces can be transmitted from the cylindrical stator to the housing, and at least one damping element which is arranged in each case between the at least one connecting element and the housing.

Claims

1. An electric machine comprising - a housing (1) and - a cylindrical stator (2) characterized by - at least one panel (3) which is secured in each case to that side of the cylindrical stator (2) facing the housing (1), wherein a gap (4) is disposed in a radial direction between the housing (1) and the respective panel (3), - at least one connecting element (5) which is secured in each case to both the housing (1) and the at least one panel (3) and by means of which forces can be transmitted from the cylindrical stator (2) to the housing (1), and - at least one damping element (6) which is arranged in each case between the at least one connecting element (5) and the housing (1).

2. The electric machine as claimed in claim 1, wherein the housing (1) has at least one guide bush (7) through which the respective connecting element (5) can be fed and by means of which the respective connecting element (5) can be aligned.

3. The electric machine as claimed in claim 2, wherein at least one of the guide bushes (5) has a ridge (8), wherein a hole (9) is incorporated in the ridge (8) and wherein the respective connecting element (5) can be aligned by means of an aligning element which is introduced into the hole (9).

4. The electric machine as claimed in one of the preceding PCT/EP2012/062468 / 2012P06540WO 17 claims, wherein provision is made for at least two panels (3) which are separated from each other in an axial direction in each case, wherein provision is made for at least one rib (10) which runs in an axial direction and connects the at least two panels (3), wherein the respective rib (10) engages in an opening of the respective panel (3) in an axial direction, and wherein at least one of the connecting elements (5) is secured to the respective rib (10) in each case.

5. The electric machine as claimed in claim 4, wherein two panels (10) are arranged on either side of the axial center of the cylindrical stator (2) and surround the cylindrical stator (2) in a circumferential direction in each case, wherein the curved surface area of the cylindrical stator (2) is composed in geometric terms of two curved surface halves which are concentric relative to the rotational axis of the electric machine, and a rib (10) is arranged in each case radially further out relative to the center of each of the curved surface halves, wherein two connecting elements (5) are secured to the respective rib (10) in each case.

6. The electric machine as claimed in claim 4, wherein two panels (4) are arranged on either side of the axial center of the cylindrical stator (2) and surround the cylindrical stator (2) in a circumferential direction in each case, wherein the curved surface area of the cylindrical stator (2) is composed in geometric terms of four curved surface quarters PCT/EP2012/062468 / 2012P06540WO 18 which are concentric relative to the rotational axis of the electric machine, and a rib (10) is arranged in each case radially further out relative to the center of each of the curved surface quarters, wherein two connecting elements (5) are secured to the respective rib (10) in each case.

7. The electric machine as claimed in one of the claims 4 to 6, wherein the respective connecting element (5) is designed as a pin and engages in a recess (11) of the respective rib (10), wherein the respective connecting element (5) has a taper (12) and the respective damping element (6) rests on the axial surface of the taper (12).

8. The electric machine as claimed in one of the claims 4 to 7, wherein the respective connecting element (5) is secured to the respective rib (10) by means of a screw connection or a welded joint.

9. The electric machine as claimed in one of the preceding claims, wherein at least one of the damping elements (6) is embodied as an elastomer or an all-metal damper element.