Paper insulation for a stator of an electric machine

Abstract

The invention relates to a paper insulation (10) for a stator (100) of an electric machine, comprising a one-piece blank (11) with a bottom section (12), side sections (14) arranged on opposite edges of the bottom section (12) and cover sections (16) arranged on the side sections, wherein the bottom section (12), the side sections (14) and the cover sections (16) are each connected to one another by a fold (20), and wherein a collar section (18) is arranged on opposite free edges of the bottom section (12) and the side sections (14), wherein the collar sections (18) are folded over parts of the bottom section (12) and the side sections (14) and the bottom section (12) and the side sections (14) are folded into a U-shape, wherein the open side of the U-shape can be covered by the folded-over cover sections (16).

Description

[0001] The invention relates to a paper insulation for a stator of an electrical machine according to the preamble of claim 1. Such paper insulation serves primarily for electrical insulation between the stator core and the stator windings arranged thereon.

[0002] The invention relates generally to the field of electrical machines. An example of an electrical machine is a permanent magnet electric motor, which consists of a stator and a rotor. The stator typically comprises a ferromagnetic core and several stator windings applied to the core. The rotor, which is mounted to rotate relative to the stator, comprises one or more permanent magnets. By alternately energizing the stator windings, a rotating magnetic field is generated, which interacts with the rotor's permanent magnet and causes the rotor to rotate.

[0003] The stator core typically consists of an annular yoke with a number of stator teeth projecting radially from the yoke. The areas between adjacent stator teeth are called slots. Winding wire wound onto the respective stator teeth forms the stator windings, which at least partially fill the slots and carry an electric current.

[0004] The winding wire of the stator windings has an insulating layer, such as an insulating varnish, to prevent an electrical short circuit between the closely spaced winding wires and, in particular, between the winding wires and the metallic stator core. However, this insulating layer can be damaged during winding assembly by contact with the stator core, especially by sharp edges of the core, leading to a short circuit between the winding wire and the core. Countermeasures include the use of plastic caps placed on the stator teeth, overmolding the stator with plastic, painting it, or using insulation made of paper or plastic film.

[0005] Especially in stators with a so-called cushion-yoke ring design, insulation using plastic or paint either leads to undesirably thick insulation layers or the insulation can be easily damaged. Since this type of motor should have the highest possible winding fill factor, a stable yet thin insulation is desired.

[0006] DE 20 2010 003 640 U1 discloses a coil body for winding with a coil wire, wherein the coil body is designed to enclose a pole tooth.

[0007] DE 10 2020 126 845 A1 discloses a stator with paper insulation consisting of an annular section from which insulating strips extend radially outwards, serving to insulate the windings.

[0008] The object of the invention is to improve a paper insulation for a stator of an electrical machine with regard to insulating effect and maximum filling level of the windings.

[0009] This problem is solved by a paper insulation with the features of claim 1.

[0010] Preferred embodiments of the invention are specified in the dependent patent claims.

[0011] The paper insulation for a stator of an electric machine consists of a single-piece blank comprising a bottom section, side sections arranged at opposite edges of the bottom section, and top sections arranged at each of the side sections, the bottom sections, side sections, and top sections being joined to one another along a fold line. Collar sections are arranged at opposite free edges of the bottom section and the side sections, the collar sections being folded over the bottom section and the side sections, and the bottom section and the side sections being folded into a U-shape, the open side of which can be covered by the folded-over top sections.

[0012] For the purposes of this invention, paper insulation is understood to encompass not only insulation made of pure paper, i.e., plant fibers, but also materials with paper-like properties. This includes not only paper but also plastic-based insulating papers or films, and multi-layered insulations with layers of various electrically insulating, natural or synthetic materials. By way of example, the commercially available synthetic insulating paper Nomex® from DuPont is mentioned here as a suitable material for producing the paper insulation according to the invention.

[0013] The paper insulation according to the invention is preferably very thin and preferably only one to a few tenths of a millimeter thick. Nevertheless, it is very resistant and easy to assemble. Most importantly, it is designed as a one-piece folded structure that covers the entire potential contact area between the windings and the stator core and electrically insulates the windings from the stator core.

[0014] The paper insulation can preferably consist of a layer of an electrically insulating natural and / or synthetic material or of several layers of electrically insulating, similar or different natural and / or synthetic materials.

[0015] This novel design of paper insulation, especially for use in a pad / yoke ring stator core, enables both easy assembly and complete insulation at the points where the winding contacts the stator core.

[0016] The slots of the padding, consisting of the inner stator ring and the stator teeth attached to it, are fitted with U-shaped folded paper insulation. The windings are then assembled on the padding. Next, the two outer sections of the paper insulation are folded inwards onto the windings in the slots, while the outer stator ring is fitted onto the padding, creating insulation between the windings and the inside of the outer stator ring. It should be noted that each sheet of paper insulation encloses one half of two adjacent windings.

[0017] The invention also relates to a stator with the described paper insulation and to an electrical machine with such a stator.

[0018] The invention is described in more detail below with reference to an exemplary embodiment and the drawings, from which further features and advantages of the invention will become apparent. Fig. Figure 1 shows a top view of the unfolded cut of the paper insulation. Fig. Figure 2 shows a side view of the paper insulation in its folded state. Fig. Figure 3 shows a view of the folded paper insulation from below. Fig. Figure 4 shows a section through the folded paper insulation. Fig. Figure 5 shows a perspective view of the folded paper insulation. Fig. Figure 6 shows an exploded view of a stator with paper insulation. Fig. Figure 7 shows a cross-section through the fully assembled stator. Fig. Figure 8 shows an enlarged section through the stator in the area of ​​the stator teeth.

[0019] The paper insulation 10 comprises a single-piece blank 11 made of a natural and / or synthetic electrically insulating material, such as paper and / or plastic fabric or plastic film. The blank may have one or more thin layers of different electrically insulating materials. The blank preferably has a thickness of one or more tenths of a millimeter.

[0020] The flat, unfolded blank 11 has a substantially rectangular shape and comprises a rectangular base section 12, at each of whose opposite longitudinal edges a side section 14 is movably deflected by means of a fold 20. At the free longitudinal edge of each side section 14, a top section 16 is movably deflected by means of a fold 20. At the free edges of the base section 12 and the side sections 14, a continuous collar section 18 is deflected by means of a fold 20.

[0021] The blank 11 is folded to form the finished paper insulation 10, whereby first the narrow collar sections 18 are folded along the folds 20 over the bottom section 12 and the side sections 14. Now the side sections 14 and the bottom section 12, together with the already folded collar sections, are folded along the connecting folds 20 to form a U-shape, so that the Fig. The state shown in Figure 2 is obtained. In this case, the collar sections 18 lie on the outer sides of the U-shaped folded paper insulation 10.

[0022] Fig. 3 shows a view from below and Fig. 4. Make a cut through the U-shaped folded paper insulation. 10.

[0023] Fig. Figure 5 is a perspective view of the U-shaped folded paper insulation 10, showing that the folded collar sections 18 form a kind of raised edge on the outer sides of the edges of the bottom section 12 and the side sections 14. The top sections 16 are still unfolded and extend in line with the side sections 14. No collar sections are arranged on the top sections 16. In this state, the paper insulation 10 is inserted into the grooves 35 of a stator core 30 as described below.

[0024] Fig. Figure 6 shows an exploded view of a stator 100 of an electric machine provided with paper insulation 10.

[0025] The stator 100 comprises a stator core 30 with an inner stator ring 32, on the outer circumference of which several stator teeth 34 are arranged at uniform intervals. The arrangement of the stator ring 32 with the stator teeth 34 is preferably formed from a single piece and is also referred to as padding. The stator teeth 34 extend radially outwards at right angles from the circumferential surface of the inner stator ring 32, with grooves 35 being formed between adjacent stator teeth 34, the base surface of which is formed by the inner stator ring 32 and the side surfaces of which are formed by adjacent stator teeth 34.

[0026] A U-shaped folded paper insulation 10 is inserted into each approximately U-shaped groove 35. The dimensions of the paper insulation 10 are selected such that the bottom section 12 of the paper insulation 10 covers the bottom of the groove 35, and the side sections 14 of the paper insulation 10 abut the side surfaces of the groove 35 formed by opposing stator teeth 34, preferably covering them completely. The collar sections 18, which are arranged on the outer end faces of the bottom section 12 and the side sections 14, project laterally from the bottom section 12 and the side sections 14 of the paper insulation 10 and bear against the end faces of the inner stator ring 32 and the stator teeth 34. This positions the paper insulation 10 axially in the groove 35 of the padding and prevents it from slipping in the groove 35.The deck sections 16 arranged on the side sections 14 initially extend in extension of the side sections 14, as shown in the . Fig. 2, Fig. 3, Fig. 4 to Fig. 5 is shown, and extend radially beyond the radially outer ends of the stator teeth 34.

[0027] In this assembly state, the windings 38 are mounted, preferably consisting of pre-assembled winding packages which are placed onto the stator teeth 34 protected by the paper insulation 10. Individual windings 38 or winding packages comprising several windings 38 can be used. Once the windings 38 are mounted on the stator teeth 34, they largely fill the slots 35 but do not protrude radially beyond the slots 35.

[0028] The cover sections 16 of the paper insulation 10 are now folded downwards and placed from above onto the windings 38 received in the grooves 34, so that the corresponding windings 38 in each groove 35 are covered and are essentially surrounded all around by the paper insulation 10.

[0029] After the windings 38 have been assembled and covered by the folded-over cover sections 16 of the paper insulation 10, the outer stator ring 36, also called the yoke ring, can be mounted. The outer stator ring 36 can, for example, be shrunk onto the outer circumferential surface of the padding, which is interrupted by the grooves 35.

[0030] Finally, a connecting ring 42 can be mounted on an end face of the stator 100, to which the connecting wires 40 of the windings 38 are electrically contacted.

[0031] Fig. Figure 7 shows a section of the stator 100 in the area of ​​the slots 35. The inner stator ring 32 with the stator teeth 34 and the mounted outer stator ring 36 can be seen. The windings 38 applied to the stator teeth 34 are accommodated in the slots 35, with each slot 35 containing parts of two adjacent windings 38.

[0032] Fig. Figure 8 shows an enlarged section of the stator 100 in the area of ​​the slots 35 before the mounting of the outer stator ring 36.

[0033] The inner stator ring 32 with the stator teeth 34 projecting from it and the grooves 35 formed between the stator teeth 34 can be seen. The paper insulation 10 is arranged in the grooves 35.

[0034] The bottom section 12 of the paper insulation 10 rests on the bottom of the groove 35, and the side sections 14 of the paper insulation 10 abut the side surfaces of the groove 35 formed by opposing stator teeth 34. The collar sections 18 of the paper insulation 10 project laterally from the bottom section 12 and the side sections 14 of the paper insulation 10 and bear against the end faces of the inner stator ring 32 and the stator teeth 34. The top sections 16 extend beyond the side sections 16 and project radially beyond the ends of the stator teeth 34. The windings 38 are placed on the stator teeth 34 and can then be covered by folding the cover sections 16 along the provided folds 20, as indicated by the folded cover sections marked with reference numeral 16' and shown with dashed lines.Afterwards, the outer stator ring 36 can be shrunk onto the pads 32, 34 which are provided with the windings. List of reference symbols 10 Paper insulation 11 Cutting 12. Ground section Section 14 16, 16' deck section 18 Collar section 20 folds 30 Stator core 32 inner stator ring 34 Stator tooth 35 Nut 36 outer stator ring 38 windings 40 connecting wire 42 Connecting ring 100 Stator 110 Rotor QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 20 2010 003 640 U1

[0006] DE 10 2020 126 845 A1

[0007]

Claims

[1] Paper insulation (10) for a stator (100) of an electric machine, characterized by a one-piece blank (11) comprising a bottom section (12), side sections (14) arranged at opposite edges of the bottom section (12) and cover sections (16) arranged at each of the side sections, wherein the bottom section (12), the side sections (14) and the cover sections (16) are each connected to each other by a fold (20), and wherein a collar section (18) is arranged at opposite free edges of the bottom section (12) and the side sections (14), wherein the collar sections (18) are folded over parts of the bottom section (12) and the side sections (14) and the bottom section (12) and the side sections (14) are folded into a U-shape, wherein the open side of the U-shape can be covered by the folded-over cover sections (16). [2] Paper insulation according to claim 1, characterized by, that the paper insulation (10) has a thickness of one to several tenths of a millimeter. [3] Paper insulation according to one of claims 1 or 2, characterized by , that the paper insulation (10) consists of a layer of an electrically insulating, natural and / or synthetic material or of several layers of electrically insulating, similar or different, natural and / or synthetic materials. [4] Stator (100) of an electric machine with a stator core (30) having an inner stator ring (32) with several radially outwardly projecting stator teeth (34), wherein slots (35) are formed between adjacent stator teeth, wherein a paper insulation (10) according to one of claims 1 to 3 and windings (38) are arranged in each slot and wherein the inner stator ring (32) and the stator teeth (34) are enclosed by an outer stator ring (36). [5] Stator according to claim 4, characterized by, that the bottom section (12) of the paper insulation (10) rests against a bottom surface of the corresponding groove (35), and the side sections (14) of the paper insulation (10) rest against side surfaces of the stator teeth (34), and the collar sections (18) of the paper insulation (10) rest against end surfaces of the inner ring (32) and the stator teeth (34), wherein stator windings (38) are applied to the stator teeth (34) over the paper insulation (10), which at least partially fill the grooves (35), and the cover sections (18) of the paper insulation (10) are folded over and placed on the stator windings (38), covering the stator windings (38) and insulating them from the outer stator ring (36). [6] Stator according to claim 5, characterized by , that the windings (38) applied to the stator teeth (34) are accommodated in the slots (35), wherein parts of two adjacent windings (38) are arranged in each slot (35). [7] Electric machine comprising a stator (100) according to any one of claims 4 to 6 and a permanent magnet rotor (110).

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