FI122632B - Arrangement to reduce vibration of the electrical machine - Google Patents

Description

FIELD OF THE INVENTION

The invention relates to an arrangement according to the preamble of claim 1 for reducing vibration of an electrical machine, an electrical machine according to the preamble of claim 9 and a method according to the preamble of claim 10 for reducing vibration of an electrical machine.

State of the art

The basic magnetic flux wave generates a rotating force field between the rotor and the stator acting in the air gap between the electrical machines. The spatial wavelength of this harmonic force field is in degrees 360 / 2p, where p is the polar pair number, and the frequency of the force field in the stator coordinate system is 2F, where F is the input frequency. Ideally, this force field is balanced and does not generate net force on the stator and rotor. Nevertheless, the stator deformations caused by this force field are so large that they are transmitted almost as such to the body of the electrical machine. The electrical machine frame is thus subjected to a forced excitation, which manifests itself as vibration and propagation of the frame and disc fields, particularly in the case of large machines, as the frame and air noise.

A rotating power wave is an indispensable part of the operation and torque generation of an electric machine and its substantial reduction is not possible. On the other hand, the amplitude of the power wave 20 is so large that even the thickest stator backs tend to deform.

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5 This occurs despite the fact that the stator package has Kimmo properties against the shaft.

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^ in the perpendicular plane are close to the corresponding values for steel. On the other hand, the deformations of the stator cp 1 are quasi-static in nature, since the frequency of the specific mode corresponding to the power wave, for example 380 Hz, is clearly higher than the excitation frequency, cc 25 for example 120 Hz. The wake-up frequency, on the other hand, is the second multiple of the input frequency.

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g The second order oscillation frequency problem is particularly significant in o large bipolar electrical machines. At higher pole numbers, the spatial wavelength of the force field is reduced, which reduces stator deformation.

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The stator is usually made up of thin plates which are joined together, for example, using back beams and welding. The outermost portion of the stator forms the back of the stator and the interior of the stator has grooves in which coils are located. Stator deformation can be reduced by thickening the stator back or stiffening the stator with external stiffeners. However, in this case, the production work steps increase and the manufacturing costs increase, the weight of the device increases and the space requirement increases.

Another way to solve the problem is to isolate the stator from the body. Isolation aims to reduce the stator deformation transfer to the body and further to vibrations and sound. A common method used in mechanical engineering is to hang the vibration source in a spring-like manner. In the case of a stator, this is made more difficult by the fact that the stator support must receive quasi-static and dynamic loads in various operating situations. Loads include, for example, gravitational force, rated torque and short-circuit torque. In addition, the stator package and the rigidity of its suspension significantly affect the characteristic frequencies of the entire motor and thereby the vibration behavior.

15 Stator isolation is a common solution in large bipolar turbogenerators.

Description of the Invention

It is an object of the present invention to provide an arrangement and method for reducing vibration of an electrical machine.

To accomplish this, the invention is characterized by the features of the characterizing part of claims 1, 9 and 10. Other preferred embodiments of the invention have the features of the dependent claims.

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In an arrangement according to the invention for reducing vibration of an electrical machine, the electrical machine o comprises a rotor and a stator at the air gap from the rotor. The stator is cc-25 formed of plates in axial direction by successive sub-packages. The stator has two parts- σ> .... .

^ between the packet the radiator's cooling channel. On the outside of the stator part packages

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° is a stator-length backrest. At least one spring element is fastened to the outer surface of at least one stator part package between the stator's back and the backrest. The spring element is attached to the backrest.

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The electrical machine according to the invention comprises a rotor and a stator at the air gap from the rotor. The stator is formed of plates in the axial direction by successive sub-chains. The stator has a radial cooling channel between the two sub-packages. There are stator-length backs on the outside of the stator sub-packages. At least one spring element is mounted between the stator's back and the backrest at least on the outer surface of the stator sub-package. The spring element is attached to the backrest.

In the method of reducing the vibration of an electric machine according to the invention, the electric machine comprises a rotor and a stator at the air gap from the rotor. In the method, the stator is formed of plates in axial direction by successive sub-packages. In the stator 10, a radial cooling channel is formed between the two sub-packages. Stator-sized back beams are mounted on the outside of the stator sub-packages. At least one spring element is secured to the outer surface of the at least one stator sub-package between the stator back and the backrest, which is attached to the backrest.

The solution of the invention is used to reduce vibrations and noise of electrical origin. The solution according to the invention significantly reduces the transmission of stator deformations caused by the basic flux of electrical machines into chassis vibrations and thereby to chassis and air noise.

In the solution of the invention, the stator, the source of vibration, is isolated from the back of the stator. The necessary elasticity between the stator backs and the beams is obtained by using spring elements 20 between the stator backs and the backs. The spring element is rigid in the circumferential and axial direction but flexible in the radial direction. The elasticity of the spring element in the radial direction provides vibration isolation.

The spring element is, for example, a leaf spring consisting of one or more steel strips. An example of a single-leaf leaf spring is the flat spring. The single-leaf leaf spring 25 has at least one substantially axial side from which the leaf spring is secured to the outer surface of the stator component package. The leaf spring may also be, for example, symmetrical with respect to a vertical axis of symmetry perpendicular to the axis of the lens. In this case, the leaf spring has two substantially axial sides, both of which are secured to the outer surface of the stator part package.

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The backrest and single-leaf leaf spring can also be machined from a single blank. This gives greater strength than when assembling two pieces.

An advantage of the solution according to the invention is that the joint is relatively rigid in both the tangential and axial directions. Tangential rigidity is particularly needed in fault conditions such as short circuiting and quick reconnection. Axial stiffness is required to maintain the axial compression force between the stator sub-packages and to control the axial eigenmode of the stator.

The solution according to the invention does not significantly increase the outer diameter of the stator because the own thickness of the spring element and the gap between the stator back and the spring element is very small. Also, the weight of the stator does not increase significantly because the weight of the spring element and its attachment is very small compared to the weight of the stator.

The invention is suitable for use with all radially cooled electrical machines where cooling is effected via radial air solids. The spring element attached to the stator sub-package and its attachments do not in any way narrow the il-15 masol between the sub-packages. The solution is suitable for both symmetrically and asymmetrically cooled electric machines.

According to an embodiment of the invention, three spring elements are attached to the outer surface of the stator part package in the circumferential direction. When the center of the angle is in the center of the stator, the angle between the spring elements is preferably 90 ° to 150 °.

The number of three attachment points is well suited to a bipolar electrical machine in which the deformation of the back of the stator package due to power distribution corresponds to a rotating ellipse over time. With three attachment points, the net force £ J applied to the stator sub-package is small.

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According to one embodiment of the invention, the spring elements of at least two axially successive cc25 components of the stator are mounted on different back beams.

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g In yet another embodiment of the invention, the stator is also isolated from the press ring of the stator o end. The stator end plate is supported by rod-like supports, such as screws, into the clamp ring so that a gap is formed between the end plate and the clamps 5, and the rod-like supports are resilient in a plane perpendicular to the stator axis.

The arrangement and method according to the invention are advantageous in large bipolar electric machines, where it particularly improves the control of second-order oscillations. The invention is also capable of reducing the transmission of higher frequency stator excitations to the body and thereby to the sound. The solution according to the invention is suitable for both two-pole machines and for multi-pole asynchronous or synchronous machines.

10 Drawing Patterns

The invention will now be described in more detail with reference to some embodiments thereof, with reference to the accompanying drawings, in which: - Figure 1 is a partial view of the electrical machine seen from the end; Figure 2 is a top view of the stator; Fig. 3 shows the attachment of the spring element to the backrest; Figure 4 shows leaf springs; Figure 5 shows a multi-strip leaf spring; Figure 6 shows the attachment of the stator end to the press ring.

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c3 Detailed Description «no 20 i o The electrical machine 1 shown in the figures is a motor or a generator.

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O) Figures 1 and 2 show an arrangement for reducing vibration of an electrical machine. The electrical machine 1g comprises a rotor 3 and a stator 2 at the end of the air gap 4 from the rotor. The stator 2 is formed by axially successive sub-packages 2a-d. Partial package 2a-d is assembled from superimposed thin plates. The stator sub-packages 2a-d are joined together by using back beams 7 and welding. Between the stator sub-packages 2a-d, a solder stick 10 is disposed 6 to separate them from each other and form a radially r channel 5 cooled to the eye 1e. The stator 2 is cooled via radial cooling channels 5. The outermost portion of the stator forms the back 9 of the stator and the interior of the stator has grooves in which coils are located (not shown in the figures).

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The outer surface 6 of the stator sub-packages 2a-d has L-back beams 7 of stator 2 length. The back beams 7 are spaced apart on the outer surface 6 of the stator 2. Most of the torque of the electrical machine 1 is transmitted 10 to the body of the electrical machine.

A spring element, a leaf spring 8b, is fastened between the stator backs 9 and the dorsal beam 7 on the outer surface 6 of the stator part package 2a-d. The spring element 8b forms a flexible connection between the stator part package 2a-d and the back beams 7. The vibration isolation of the stator back 9 is based on the elasticity of the spring element 8b in the radial direction r. A small gap 14 is left between the back 9 and the back beam 7 of the stator 2 consisting of the partial packages 2a-d.

The spring element 8a-c is secured to the back beam 7 by welding. In Figure 3, the spring element 8b is secured to the back beam 7 by welding joint 12b by welding. The spring member 20b blade 8b is embedded in the back bar 7. In this case, the diameter of the stator 2 and the back bar 7 will not increase.

For example, three spring elements 8a-c in the circumferential direction c are attached to one of the stator part packages 2a-d. When the center of the angle is in the center of the stator then the spring elements

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The angle between q is preferably 90 ° to 150 °. In a balanced solution, the spring elements are

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25 substantially equal increments, i.

° The stator part package 2a-d is attached to three stator backs 7 on the spring members-

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£ via cents. The number of three approximately equally spaced attachment points is preferred g in a bipolar electrical machine in which the deformation of the back 9 of the stator package 2a-d g caused by the force distribution corresponds to a rotating ellipse over time. Thus, the total force exerted on the sub-package resulting from the attachment is small and the center of the sub-package 2a-d remains in place. For example, if there are 6 back beams, one stator sub-package 2a-d is secured to the three back beams 7 via spring elements 8a-c.

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In the axial direction, the spring elements 8a-c of successive stator sub-packages 2a-d are attached to different back beams 7. In FIG. c is attached to the same backrest 7.

Figures 4a) -c) show two different single-strip leaf springs, flat springs 8a-b. Fig. 4a) shows a flat spring 8a seen from the side and Fig. 4b) seen from above. The flat spring 8a is a single-curved plate having an angle dividing the bar 8a into two 10 parts 13a-b. The flat spring 8a has two substantially axial sides a 1a-b. The flat spring 8a is secured to the outer surface 6 of the stator part package 2a-d from the axial side 11a of the first part 13a of the bar by a welding joint 12a. The flat spring 8a engages the lower surface of the back beam 7 facing the stator 2 from the second portion 13b of the bar.

In Fig. 4c), the flat spring 8b is a two-sided bent plate having two corners dividing the bar into three parts 12a-c. The flat spring 8b has two substantially axial sides 11a-b. The flat spring 8b is secured to the outer surface 6 of the stator part package 2a-d from the axial side aa of the first bar 13a and the third bar 13c by a welding joint 12a. The ferrule spring 8b engages the lower surface of the back beam 7 facing the stator 2 from the second portion 13b of the bar.

The flat spring 8b of Fig. 4c) is symmetrical with respect to a vertical axis of symmetry perpendicular to the axis. The flat spring 8b is mounted on the underside of the backrest 7 (M such that the symmetry axis s of the flat spring 8b is on the axial axis 25 of the backrest 7.

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The flat spring 8a-b is preferably of elongated shape. Flat spring 8a-b

The ec a has a width of 10..40% of the circumferential length c of the flat spring.

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g 30 Figure 5 shows a leaf spring 8c consisting of a plurality of strips 20. In Figure 5, the strips 20 are of equal length but may also be of varying lengths, for example, when shortened circumferentially from first edge to second edge of backrest 7.

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In Figures 4 and 5, the spring element 8a-c is attached to the underside of the backrest 7. Such a fastening is more advantageous to manufacture than the fastening of Figures 1-3, in which the spring element 8b is embedded in the back beam 7.

5 Each sub-package 2a-d of the stator 2 of the electrical machine 1 generates torque. If the stator sub-packages 2a-d are tightly pressed and the sub-packages 2a-d are held together, the sub-packages 2a-d need not be fastened by means of spring elements to the back beams 7 at several points. A single part package may not be completely attached to the back beams. Then, the connections made by solenoids 10 between the subpackets 2a-d transfer loads 10 and the force is transferred from one subpacket 2a-d to another.

Then, each stator part package 2a-d does not need to be isolated from the body of the electrical machine 1. Thus, for example, each of the second sub-packages 2a-d is provided with spring elements 8a-c between the stator backs 9 and the back beams 7, or 40-60% of the stator sub-packages 2a-d, for example, are provided with spring elements 8a-c.

The vibration insulation of the electrical machine 1 can be increased by isolating the stator 2 from the press clamp rings 15, Fig. 6. The stator 2 end plate 16 supports the stator 2 formed by the part packages 2a-d in the axial direction a and secured to the outermost part package 2a. The back bar 7 is secured to the end plate 16 by welding. The end plate 16 of the stator 2 is supported by rod-shaped supports 17 on the press ring 15. In Figure 6, the rod-like support is a screw. The rod-like supports 17 provide a gap 18 between the end-plate 16 and the clamping ring 15. The vibration insulation of the stator-end-plate 16 is based on the spring tension of the rod-like supports 17 in the radial direction r.

w 25 i o The thread portion of the screw 19 is short relative to the free dimension of the screw, for example, 10..35% of the free dimension of the screw.

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g Figure 6 shows one end of stator 2. It is possible to implement the solution at both ends of the stat 30 at the same time.

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The solutions shown in the figures significantly reduce frame vibrations and bearing vibrations caused by the basic flow of electrical machines. The solution also reduces frame vibrations and bearing vibrations caused by other flow components.

5 Parts list: 1 electric machine; 2 stator; 2a-d stator sub-package; 3 rotor; 4 airspace; 5 radial cooling channel; 6 outer surface; 7 backrest; 8a, 8b, 8c leaf spring; 9 stator back; 10 sticks; lla-b page; 12a-b welding joint; 13a, b, c portion of the bar; 14 slit; 15 compression ring; 16 end plate; 17 rod support; 18 gaps; 19 threaded sections; 20 strips; a axis direction; c circumferential direction; L length; r beam direction; s axis of symmetry.

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Claims (10)

An apparatus for reducing vibration in an electric machine, the electric machine (1) comprising a rotor and at a distance of an air gap from the rotor of a stator (2), and the stator (2) being formed by plaques in sub-packages (2a) d) positioned one after the other in the axis direction, and in which the stator (2) between two sub-packages (2a-d) Anns in the direction of the radius (r) a cooling channel (5), and on the outer surface (6) of the stator sub-package (2a) d) Other back beams (7) with the same mat (L) as the stator (2), characterized in that at least one spring element (8a-c) is attached to the surface of at least one of the sub-packages (2a-d). back (9) and a back beam (7), and each spring element (8a-c) is secured to a back beam (7). A device according to claim 1, characterized in that three spring elements (8a-c) are fixed in the peripheral direction to the outer surface (6) of the stator's sub-package (2a-d). 15 3. A device according to claims 1-2, characterized in that the spring clamp (8a-c) on at least two of the stator sub-packages (2a-d) located one after the other in the axis direction is fixed in different back beams (7). 4. A device according to claims 1-3, characterized in that the spring element (8a-c) is a leaf spring formed by at least one leaf (20). A device according to claims 1-4, characterized in that the single-leaf leaf spring (8a-c) has at least one side (1a-b) substantially in the axis direction (a) and the single-leaf leaf spring (8a-c) is from the axially directed side (1a-b) o ^ fixed in the outer surface (6) of the stator's sub-package. ch o i 6. A device according to claim 5, characterized in that the single-blade leaf spring (8a-c) is symmetrical relative to the vertical axis of symmetry (s) perpendicular to the axis direction, and the single-leaf leaf spring (8a-c) ) has two substantially directed sides (1a-b) in the axis direction. o δ (M A device according to claims 1-6, characterized in that the gift lp (16) of the stator (2) is supported by rod-shaped supports (17) against the clamping ring (15), so that between the gable plates (16) and the clamping ring (15) there is a column. A device according to claim 7, characterized in that the rod-shaped support 5 (17) is a screw. An electric machine, which electric machine (1) comprises a rotor and at a distance of an air gap from the rotor a stator (2), and the stator (2) is formed by plaques in sub-packages (2a-d) positioned one after the other in the axis direction, and in which stator (2) between two sub-packages (2a-d) is located in the direction of the radius (r) a cooling channel (5), and on the outer surface (6) of the stator sub-package (2a-d) there are back beams (7) of the same measured ( L) as the stator (2), characterized in that at least one spring element (8a-c) is attached to the outer surface of at least one of the sub-packages (2a-d) between the stern's back (9) and a back beam (7), and each spring element (8a-c) is attached to a back beam (7). A method of reducing vibration in an electric machine, which electric machine (1) comprises a rotor and at a distance of an air gap from the rotor a stator (2), and in which method the stator (2) is formed by plaques in sub-packages ( 2a-d) are positioned one after the other in the axis direction, and in which stator (2) between two sub-packages (2a-d) is formed in the direction of the radius (r) a cooling channel (5), and on the outer surface (6) of the stator sub-package (2a) d) there are back beams (7) with the same measured (L) as the stator (2), characterized in that at least one spring element (8a-c) is fixed between the back of the stator on at the outer surface of at least one of the sub-packages (2a-d) (9) and a back beam (7), and each spring element (8a-c) is secured to a back beam (7). δ (M CNJ cp I '- 0 X cc CL 01 LO δ o δ {M