An induction motor

Abstract

An induction motor 10 comprising a casing 11, at least one motor winding 14 and a terminal block 12 external to the casing, the one motor winding having multiple individual strands 16. The motor furt

Description

The present invention relates to an induction motor, specifically to an insert of an electric induction motor which enables the multiple copper strands of the motor windings of an induction motor to be electrically connected to a power supply external of the induction motor. Known induction motors include a casing within which is housed components which include a stator having multiple motor windings connected to a power supply via a terminal block external to the casing, and a rotor connected to a shaft. Applying power to the motor windings causes the rotor and therefore the shaft to rotate. The casing contains oil to lubricate and keep the components cool. The multiple copper strands are required to be electrically connected to the power supply which is located external to the casing, typically via a terminal block which is mounted on the casing. The multiple copper strands therefore must pass through a sealable aperture in the casing. One way of sealing the aperture and enabling the multiple copper strands to pass through the casing is to house the multiple strands within a known device such as a bulkhead connector or penetrator which seals against the casing. However, such known devices have several disadvantages. Firstly, the materials from which known bulkhead connectors and penetrators are made from do not meet the stringent material compatibility and testing requirements of the aggressive oil used in the motor casing. Secondly, although the bulkhead connector or penetrator can be adequately sealed against the motor casing itself, the multiple strands themselves are also required to be sealed relative to the bulkhead connector or penetrator. This is achieved by encasing the multiple strands in a sealing resin inside the bulkhead connector or penetrator. However, the multiple strands are tightly wound with adjacent strands in physical contact with each other, which prevents the sealing resin from forming a seal around all of the multiple strands and allowing oil inside the casing to escape due to capillary action between the multiple adjacent strands. Thirdly, the bulkhead connectors or penetrators are bulky, requiring space inside the motor casing, which already has a limited size envelope. The space requirement is more problematic for motors with multiple motor windings where multiple bulkhead connectors or penetrators are required on the casing. An object of the present invention is therefore to provide an improved induction motor which enables the multiple copper strands of the motor windings to be connected to a power supply located externally of the motor casing. Thus, according to the present invention, there is provided an induction motor comprising a casing, at least one motor winding, and a terminal block external to the casing, the at least one motor winding having multiple individual strands, the induction motor further comprising an insert inside which the multiple individual strands can pass through continuously to the terminal block, in which the insert is sealingly engageable with an aperture in the casing and with the multiple individual strands to prevent fluid leaking from the casing. Advantageously, the individual irregular strands are thus prevented from coming into contact with each other and providing a path for fluid to escape from the casing. Advantageously, the insert enables an electrical connection to be made between the motor winding and the power supply in a continuous manner and therefore without having to physically disconnect the motor winding either side of the casing and reconnect via a connector installed on the casing. Furthermore, the use of the insert reduces the space consumed inside the motor casing as it less complex than a bulkhead connector. Further still, the insert can be made, for example moulded, from a range of materials which meet the stringent oil compatibility requirements. Preferably, the insert comprises a main body and a single barrier, the main body defining an inner region through which the multiple individual strands can pass through continuously to the terminal block. Preferably, the main body has an outer surface which is sealingly engageable with the casing. Preferably, the inner region comprises a first interior region and second interior region divided by the barrier, in which the barrier is sealingly engageable with the multiple individual strands to prevent fluid in the casing from moving from the first interior region to the second interior region. Preferably, the first interior region includes a resin to sealingly engage the barrier with the multiple individual strands. Preferably, the main body and the barrier are a one-piece component. Preferably, the barrier is sealingly engageable with the multiple individual strands to prevent fluid in the casing from moving from the first interior region to the second interior region. Preferably, the barrier comprises a circular disk and a plurality of apertures, each aperture of the plurality of apertures configured to receive an individual strand of the multiple individual strands so as to separate each individual strand from adjacent individual strands. Preferably, the individual strands are collimated relative to each other such that they do not come into contact with each other and thereby prevent the creation of a fluid leak path. Preferably, the adjacent apertures are spaced apart by a minimum first distance so as to separate each individual strand from adjacent individual strands for a minimum second distance. Preferably, each individual strand is substantially parallel to each adjacent individual strands for the minimum second distance. Preferably, the resin extends to at least the minimum second distance from the barrier. Preferably, only one of the individual strands passes through each aperture of the plurality of apertures, that is, each strand is allocated a single aperture such that each aperture has only one strand passing or extending through it. Preferably, each of the individual strands are collimated relative to each other. Preferably, each individual strand is sealed relative to each aperture of the barrier through which it extends through, that is individual strands are sealed in individual apertures to seal the multiple strands relative to barrier and therefore prevent fluid leaking from the casing. Preferably, above the barrier, in the region where resin is present (the potted region), each individual strand is sealed relative to each and every other individual strand with no bubbles, air pockets or regions unwetted by resin. Preferably, the first interior region has an open end. According to another aspect of the present invention there is provided an insert for an induction motor, the insert configured to enable multiple individual strands of at least one motor winding of an induction motor to pass through continuously to a terminal block external to or remote from the casing, in which the insert is sealingly engageable with a casing of the induction motor and with the multiple individual strands to prevent fluid leaking from the casing. According to another aspect of the present invention there is provided a method of assembling an induction motor comprising the steps of providing a casing, providing at least one motor winding and a terminal block external to the casing, the at least one motor winding having multiple individual strands, providing an insert having a main body and a barrier, the main body defining an inner region having an open end and comprising a circular disk with a plurality of apertures, inserting each strand of the multiple individual strands through one aperture of the plurality of apertures such that one strand passes through one aperture of the multiple individual strands . Preferably, the method includes the step of introducing a resin into the inner region via the open end. Preferably, each individual strand is separated from adjacent individual strands for a minimum second distance from the barrier before the step of introducing the resin. Preferably, the insert only employs a single barrier within and part-way along its length (indicated by arrow L), facilitating the filling with resin without turbulence for the avoidance of entraining air bubbles during the filling process and the removal of air bubbles that may be entrained during the filling process. Preferably, the open end is of a large enough diameter to allow pouring of resin without creating turbulence for the avoidance of entraining air bubbles during the filling process. Preferably, the insert is oriented substantially vertically when the resin is introduced into the inner region via the open end to enable air bubbles in the resin to move vertically upwards and escape from the inner region via the open end. The invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a perspective view of an induction motor according to the present invention, Figure 2 is a perspective view of part of the induction motor of Figure 1, Figures 3 and 3A are schematic views of part of the induction motor of Figure 1 with and without an insert of the present invention, and Figure 4 is an end sectional view of part of the insert of the induction motor of Figure 1. Figure 5 is a perspective sectional view of part of the insert of the induction motor of Figure 1, Figure 6 is an enlarged perspective sectional view of part of the insert of the induction motor of Figure 1, and Figures 7 to 15 are photographs of part of the induction motor of Figure 1. In Figures 1 to 3A, an induction motor 10 comprises a casing 11 within which a rotor 13 and a stator 15 are housed and arranged in a known way. The stator 15 includes multiple motor windings 14 (only one of which is shown) which are connected to a power supply (not shown) via a terminal block 12. Applying power to the motor windings 14 causes the rotor, and a shaft 17 connected thereto, to rotate. It will be understood that the induction motor can comprise multiple electric windings 14 and that each motor winding 14 is formed by coiling together a plurality of individual copper strands 16. The induction motor 10 includes two end bellhousings 19 which form a seal against the casing 11 to retain a fluid F, typically mineral oil, within the casing 11 and enable the fluid F to cool and lubricate the induction motor. The induction motor 10 includes a hollow cylindrical insert 18 having a main body 20 and a barrier 22 in the form of a circular disk. The main body 20 and the barrier 22 are a one-piece insulating material, for example a plastic component, formed by machining from a single plastic bar. Alternatively, the component can be formed by moulding, for example, injection moulding. In the schematic representation of Figure 3, only one insert 18 is shown. It will be understood that the number of inserts 18 required corresponds to the number of motor windings 14. In Figure 5, the main body 20 defines an inner region 24 having a first interior region 28 positioned on a stator side S of the motor 10 having an interior surface 25, and a second interior region 30 positioned on a power supply side P of the motor 10. The first 28 and second 30 interior regions are divided by the barrier 22. The first interior region 28 has a first open end 33 which is located inside the casing 11, and therefore exposed to the fluid F inside the motor 10, and the second interior region 30 has a second open end 34 which is located outside the casing 11, and therefore exposed to the environment outside of the casing 11. The barrier 22 is positioned part-way along the length L of the main body 20 of the insert 18 between the first open end 33 and the second open end 34. The main body 20 includes a groove 29 into which an O-ring 31 locates to enable a seal to be formed between the casing 11 and the insert 18 as will be described further below. In alternative embodiments, two O-rings can be used as back-up in the event one of the O-rings fail. The barrier 22 includes a plurality of apertures 32 arranged on concentric equally spaced circles with each aperture 32 spaced circumferentially equally on each concentric circle so as to maximise the separation between adjacent apertures 32. The apertures 32 are sized and spaced with a minimum distance X so as to allow individual strands 16 of the motor winding 14 to be separated and sealed relative to the barrier 22 as will be described below. In this embodiment, each aperture has a diameter of 1,2mm with a pitch spacing between adjacent concentric circles of 5mm, resulting in a spacing X of 3.8mm. The inner region 24 of the insert 18 undergoes a known surface plasma treatment to ensure the epoxy resin adheres to any surface it comes into contact with as will be described further below. The insert 18 is assembled and installed into the induction motor 10 as follows: Firstly, the motor windings 14 are inserted into the stator 15. Each strand 16A of the motor windings 14 is inserted through each aperture 32 of the barrier 22. The strands 16A in strand zone A are tightly wound such that a significant proportion, if not all, adjacent strands 16A are in contact with each other. After individual strands 16Ahave been inserted into individual apertures 32, a second strand zone B is created either side of the barrier 22, in the first 28 and second 30 interior regions. In the second strand zone B, individual strands 16B1 (in the first interior region 28) and individual strands 16B2 (in the second interior region 30) have been separated sufficiently by the distance X between adjacent apertures 32, in this embodiment 3.8mm such that each of the individual strands are collimated, i.e. adjacent strands are parallel and therefore not in contact with each other for a second distance Y, in this embodiment, 15mm. By being collimated, the individual strands 16 do not come into contact with each other, and therefore a leak path is not created. After each of the individual strands are collimated, the epoxy resin R, for example, epoxy adhesive is then introduced into the first interior region 28 via the open end 33 in sufficient volume such that the resin extends at least the distance Y towards the stator side S, that is, a sufficient distance to enable the resin R to envelop the separated strands 16B1 and form a seal around firstly, each individual strand 16B1, secondly, between each strand 16B1 and the aperture 32 through which it passes, and thirdly, between each strand 16B1 and the interior surface 25 of the first interior region 28. As a result, a seal is formed between the interior first region 28 and the second interior region 30, ensuring that no fluid F can move from the interior first region 28 to the second interior region 30. The insert is oriented vertically when the resin R is introduced into the first interior region 28 to enable any air bubbles in the resin to move vertically upwards and escape from the first interior region 28 of the inner region 24 via the open end 33. The epoxy resin R is optionally de-gassed and the curing temperature is controlled to ensure the epoxy resin R forms correctly to form a reliable and long-lasting seal. In the second interior region 30, the strands 16B2 have also been separated sufficiently such that adjacent strands are parallel and therefore not in contact with each other, however, no epoxy resin is added to the second interior region 30 as a seal has already been formed between the first interior region 28 and the barrier 22, and therefore it is not critical that the strands 16B2 remain separated as no fluid F will be present. In zone C, the strands 16C which protrude from the insert 18 are crimped to create a crimped portion 36 for subsequent insertion into the terminal block 12. The motor windings 14, stator 15, insert 18, crimped portion 36 and terminal block 12 are presented as a one piece sub-assembly 38. The stator 15 is then assembled inside the casing 11 and the insert 18 is fed through the aperture 40 (Figure 3) in the casing 11. The O-ring 31 forms a seal between the insert 18 and the casing 11 to prevent the fluid F from escaping from the casing 11. After the sub-assembly 38 is installed on the casing 11, the crimped portion 36 is passes through the terminal block 12 so as to make an electrical connection available between the motor winding 14 of the stator 15 through the terminal block 12 and casing 11. The crimped portion 36 is then connected to the power supply (not shown). It can be seen therefore that the insert 18 enables the motor winding 14 to be connected to a power supply external of the casing 11 without breaking the physical continuity of the strands 16 of the motor winding 14, for example, by requiring those strands 16 to be connected to each other with a connector such as a spade connector. Such a continuous physical connection of the strands 16 provides a more robust and reliable connection of the motor winding 14 inside the casing 11 to the power supply, and seals the strands 16 of the motor winding 14 relative to the casing 11 and therefore prevents fluid F from leaking from the casing 11 In Figures 7 to 14, photographs of the motor winding sub-assembly 38 are shown together with sections Xi to Xs through the insert 18. In Figure 8, the insert 18 has been sectioned to show the spacing of adjacent strands 16A,16B1,16B2 in zones Aand B. Figure 9, viewing from the right of section Xi, shows adjacent strands 16B2 separated and substantially parallel. Figure 10, viewing from the left of section Xi, shows adjacent strands 16B2 separated and substantially parallel. Figure 11 viewing from the right of section X2, shows adjacent strands 16B1 separated and substantially parallel. Figure 12 viewing from the left of section X3, shows adjacent strands 16A, some of which are separated and some of which are in contact. Figure 13 viewing from the left of section X4, shows less adjacent strands 16A separated and more in contact compared to Figure 12. Figure 14 viewing from the left of section X5, shows less adjacent strands 16A separated and more in contact compared to Figure 13. Figure 15 shows the motor windings 14 passing through the insert 18.

Claims

1. An induction motor (10) comprising a casing (11), at least one motor winding (14) and a terminal block (12) external to the casing (11), the at least one motor winding (14) having multiple individual strands (16), the induction motor (10) further comprising an insert (18) inside which the multiple individual strands (16) can pass through continuously to the terminal block (12), in which the insert (18) is sealingly engageable with an aperture (40) in the casing (11) and with the multiple individual strands (16) to prevent fluid (F) leaking from the casing (11).

2. An induction motor (10) according to claim 1 in which the insert (18) comprises a main body (20) and a barrier (22), the main body (20) defining an inner region (24) through which the multiple individual strands (16) can pass through continuously to the terminal block (12).

3. An induction motor (10) according to claim 2 in which the main body (20) has an outer surface (26) which is sealingly engageable with the casing (11).

4. An induction motor (10) according to claim 2 or 3, the inner region (24) comprises a first interior region (28) and second interior region (30) divided by the barrier (22), in which the barrier (22) is sealingly engageable with the multiple individual strands (16) to prevent fluid (F) in the casing (11) from moving from the first interior region (28) to the second interior region (30).

5. An induction motor (10) according to claim 4 in which the first interior region (28) includes a resin (R) to sealingly engage the barrier 28 with the multiple individual strands (16).

6. An induction motor (10) according to any one of claims 2 to 5 in which the main body (20) and the barrier (22) are a one-piece component.

7. An induction motor (10) according to any one of claims 2 to 6 in which the barrier (22) is sealingly engageable with the multiple individual strands (16) to prevent fluid (F) in the casing (11) from moving from the first interior region (28) to the second interior region (30).

8. An induction motor (10) according to one of claims 2 to 7, the barrier (22) comprising a circular disk and a plurality of apertures (32), each aperture (32) of the plurality of apertures (32) configured to receive an individual strand of the multiple individual strands (16) so as to separate each individual strand from adjacent individual strands.

9. An induction motor (10) according to claim 8 in which adjacent apertures (32) are spaced apart by a minimum first distance (X) so as to separate each individual strand from adjacent individual strands for a minimum second distance (Y) from the barrier (22).

10. An induction motor (10) according to claim 9 in which each individual strand is substantially parallel to each adjacent individual strands for the minimum second distance (Y).

11. An induction motor (10) according to claim 9 or 10 when dependent on claim 5 in which the resin (R) extends to at least the minimum second distance (Y) from the barrier (22).

12. An induction motor (10) according to any one of claims 8 to 11 in which only one of the individual strands (16) passes through each aperture (32) of the plurality of apertures (32).

13. An induction motor (10) according to any preceding claim in which each of the individual strands (16) are collimated relative to each other.

14. An induction motor (10) according to claim 12 or 13 in which each individual strand (16) is sealed relative to each aperture (32) through which it extends through.

15. An induction motor (10) according to any preceding claim in which a or the first interior region (28) has a first open end (33) and a second open end (34).

16. An induction motor (10) according to claim 15 when dependent on claim 2 in which the barrier is a single barrier (22) positioned part-way along the length (L) of the insert between the first open end (33) and the second open end (34).

17. An insert (18) for an induction motor (10), the insert (18) configured to enable multiple individual strands (16) of at least one motor winding (14) of an induction motor (10) to pass through continuously to a terminal block (12) external to the casing (11), in which the insert (18) is sealingly engageable with a casing (11) of the induction motor (10) and with the multiple individual strands (16) to prevent fluid (F) leaking from the casing (11).

18. A method of assembling an induction motor (10) comprising the steps of: providing a casing (11),providing at least one motor winding (14) and a terminal block (12) external to the casing (11), the at least one motor winding (14) having multiple individual strands (16),providing an insert (18) having a main body (20) and a barrier (22), the main body (20) defining an inner region (24) having an open end (33) and comprising a circular disk with a plurality of apertures (32),inserting each strand of the multiple individual strands (16) through one aperture (32) of the plurality of apertures (32) such that one strand passes through one aperture of the multiple individual strands (16).

19. A method of assembling an induction motor (10) according to claim 18 in which a resin (R) is introduced into the inner region (24) via the open end (33).

20. A method of assembling an induction motor (10) according to claim 19 in which each individual strand is separated from adjacent individual strands for a minimum second distance (Y) from the barrier (22) before the resin (R) is introduced into the inner region (24).

21. A method of assembling an induction motor (10) according to claim 20 in which each individual strand is substantially parallel to each adjacent individual strands for the minimum second distance (Y).

22. A method of assembling an induction motor (10) according to any one of claims 18 to 21 in which the insert (18) is oriented substantially vertically when the resin (R) is introduced into the inner region (24) via the open end (33) to enable air bubblesin the resin (R) to move vertically upwards and escape from the inner region (24) via the open end (33).IntellectualPropertyOfficeApplication GB2503865.4Search report under Section 17 of the Patents Act 1977Date search completed: 13 August 2025Claims searched: 1-22International classificationSubclass and subgroup Valid from H02G15 / 013 01 / 01 / 2006 H02K5 / 22 01 / 01 / 2006Field of searchWorldwide search of patent documents classified in the following areas of the IPC:H02K, H02G, H01RDatabases used in the preparation of this search report:SEARCH-PATENTDocuments considered to be relevantPatent literatureCategory Relevant claims Document of relevance X 1-22 CN 201490819 U (WUXI XISHAN ANDA EXPLOSION PROOF ELECTRICAL EQUIPMENT), figure 1Intellectual Property Office is an operating name of the Patent Office www.gov.uk / ipoX 1-5, 7-18 JP 2000312429 A (ISHIKAWAJIMA HARIMA HEAVY IND), figures 1,2; paragraphs [0003], [0008], [0021], [0030], [0031], [0037] X 1-3, 7-10, 12-18 JP 2011058388 A (TOYOTA), figures 1,2; paragraphs [0020]-[0028] X 1-5, 7-21 US 2006 / 0068626 A1 (HASEGAWA), figures 1 &2 and paragraphs [0027]-[0031] X 1-4, 6-10, 12-18 US 2013 / 0121815 A1 (TSUBOI), figure 1; paragraphs [0027]-[0028] X 1-22 US 5889343 A (BRYANT et al), figures 1-3 Non-patent literature Category Relevant claims Document of relevanceCategoriesLetter or DescriptionsymbolX Document indicating lack of novelty or inventive step.Y Document indicating lack of inventive step, if combined with anotherdocument of the same category.& Member of the same patent family.Letter or symbol Description A Document indicating technological background. P Document published on or after the priority date but before the fling date of the present application. E Earlier application published on or after the filing date of the present application.

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