Stator and electric motor

Abstract

A stator (1) comprises: an iron core (10) provided with a back yoke (11) and a plurality of teeth (12) that protrude from the back yoke toward a movable element (5) side and that are arranged at intervals along a drive direction of the movable element; a plurality of coils (20) respectively wound around the teeth; and a sealing member (30) providing a liquid-tight seal to each slot formed between mutually adjacent teeth. The sealing member has a first sealing part (31) disposed in a gap between the tips of the mutually adjacent teeth, and a second sealing part (32) disposed, on at least one side of the teeth in the thickness direction, in a position covering the end surfaces at least on the tip side of all the teeth in the thickness direction and the end surfaces of all the first sealing parts in the thickness direction. The second sealing part can be brought into close contact with a housing (6) housing the iron core and the coils. The first sealing part and the second sealing part are integrally formed.

Description

Stator and motor

[0001] The present disclosure relates to a stator and an electric motor.

[0002] A rotating electric machine is known in which a coolant flows inside a plurality of slots provided along the circumferential direction of a cylindrical stator core to cool coils arranged in the slots (see, for example, Patent Document 1). In such a rotating electric machine, a resin layer is formed at the radially inner opening of each slot, and a seal member is disposed between both axial end faces of the stator core and a pair of cases that cover them, thereby forming a coolant flow path.

[0003] Japanese Patent Application Laid-Open No. 2003-289652

[0004] Each of the above-mentioned seal members is pressed axially outward against the stator core by the corresponding case. However, if the axial dimensions of the stator are uneven, a gap may form between the seal member and the stator core. If the refrigerant leaks from this gap, it may contaminate other components that make up the rotating electrical machine. Therefore, it is desirable to be able to more reliably seal the refrigerant flow path that cools the coils attached to the stator core.

[0005] One aspect of the present disclosure is a stator comprising: a back yoke; an iron core having a plurality of teeth protruding from the back yoke toward a movable member and spaced apart along the drive direction of the movable member; a plurality of coils wound around each of the teeth; and a sealing member that liquid-tightly seals each slot formed between adjacent teeth, the sealing member comprising: a first sealing portion arranged in the gap between the tips of the adjacent teeth; and a second sealing portion arranged on at least one side of the teeth in the thickness direction, in a position that covers at least the thickness-wise end faces of the tip sides of all of the teeth and the thickness-wise end faces of all of the first sealing portions, and that can be tightly fitted to a housing that accommodates the iron core and the coils, wherein the first sealing portion and the second sealing portion are integrally formed.

[0006] 1 is a perspective view showing a portion of an electric motor according to an embodiment of the present disclosure. FIG. 2 is a schematic view showing the AA cross section of the electric motor shown in FIG. 1. FIG. 3 is a perspective view showing a portion of an iron core of a stator according to an embodiment of the present disclosure. FIG. 4 is a cross-sectional view of a portion of a stator according to an embodiment of the present disclosure. FIG. 5 is a longitudinal cross-sectional view of a portion of a sealing member provided in the stator shown in FIG. 4. FIG. 6 is a perspective view showing a cross section of a first modified example of a sealing member provided in the stator shown in FIG. 4. FIG. 7 is a cross-sectional view of a second modified example of a sealing member provided in the stator shown in FIG. 4. FIG. 8 is a partial cross-sectional view showing a modified example of the electric motor shown in FIG. 1.

[0007] A stator 1 and an electric motor 100 according to an embodiment of the present disclosure will be described below with reference to the drawings. The electric motor 100 according to this embodiment is, for example, a rotary motor. As shown in FIG. 1 , the electric motor 100 includes a cylindrical stator 1 having an axis X as its central axis, and a columnar rotor (moving element) 5 arranged coaxially with a predetermined gap radially inside the stator 1. As shown in FIG. 2 , the electric motor 100 also includes a housing 6 that accommodates the stator 1.

[0008] 2, the rotor 5 includes a cylindrical main body 51 having a central axis on the axis X, and a shaft 52 that protrudes outward along the axis X from one end face of the main body 51 in the axis X direction. The main body 51 and the shaft 52 are arranged coaxially and integrally formed. The rotor 5 is supported rotatably about the axis X by a bearing (not shown) attached to the housing 6, which will be described later. The main body 51 is arranged at a position overlapping with the stator 1 and the housing 6 in the axis X direction, and the shaft 52 is arranged at a position where its tip protrudes outward from the housing 6 in the axis X direction.

[0009] 1 and 2, the stator 1 includes a substantially cylindrical core 10 that surrounds the radially outer side of the outer peripheral surface of the main body 51 of the rotor 5, a coil 20, and a sealing member 30. The core 10 is an integrated laminate formed by stacking a plurality of members, each member being punched into the same shape from thin plates made of a magnetic material such as an electromagnetic steel plate, in the plate thickness direction. That is, in this case, the stacking direction of the plurality of thin plate members is defined as the thickness direction of the core 10. As shown in FIGS. 1 and 3, the core 10 includes a cylindrical back yoke 11 whose central axis is the axis X, and a plurality of teeth 12 that protrude radially inward from the inner peripheral surface of the back yoke 11 and are arranged at equal intervals in the circumferential direction.

[0010] A slot S is formed between each pair of circumferentially adjacent teeth 12. As shown in Fig. 3, each slot S has a rectangular opening 14 that opens radially inward and extends over the entire length in the direction of the axis X.

[0011] The coils 20 are, for example, a group of multiple coils corresponding to three phases, U, V, and W, and are wound around each tooth 12 using distributed winding or concentrated winding. That is, the coils 20 are arranged so that each phase (U, V, W) is repeated in a predetermined order around the circumference. As a result, when a three-phase AC drive current is input to the coils 20, a magnetic flux is generated that rotates the rotor 5 about the axis X.

[0012] As shown in Fig. 2, the sealing member 30 includes a first sealing portion 31 and a second sealing portion 32. The first sealing portion 31 is formed, for example, as shown in Fig. 4, by filling a resin material such as epoxy resin or unsaturated polyester into a wall shape having a predetermined thickness at a position that blocks the opening 14 of each slot S. When forming the first sealing portion 31, for example, a jig (not shown) that defines a cavity to be filled with molten resin material may be placed using a known method, and the jig may be removed after the filled resin material has hardened.

[0013] The first sealing portion 31 has an inner circumferential surface 31i that is continuous with the inner circumferential surfaces of the tips of the teeth 12 located on both sides in the circumferential direction about the axis X. The first sealing portion 31 also has an outer circumferential surface 31o that is positioned at a position offset a predetermined distance radially outward from the inner circumferential surface 31i. In other words, the first sealing portion 31 liquid-tightly seals the openings 14 of each slot S, forming an enclosed space (flow path) within each slot S that extends in the direction of the axis X.

[0014] 2 , the second sealing portions 32 are formed of annular members with a substantially rectangular cross section made of a resin material different from that of the first sealing portions 31, and one is disposed on each side of the core 10 in the direction of the axis X. Each second sealing portion 32 is disposed coaxially with the axis X and has an annular bottom surface (end surface) 32b that continuously covers the end surfaces of the tips of all of the teeth 12 on the corresponding side in the direction of the axis X. Furthermore, the second sealing portion 32 has an inner circumferential surface 32i having an inner diameter dimension that is the same as or slightly larger than the inner circumferential surface 31i of the first sealing portion 31, and an outer circumferential surface 32o having an outer diameter dimension that is the same as or slightly smaller than the outer circumferential surface 31o of the first sealing portion 31.

[0015] Furthermore, the second sealing portions 32 are integrated with the first sealing portions 31 by insert molding when the first sealing portions 31 are molded. That is, as shown in Fig. 5 , a part of the bottom surface 32b of each second sealing portion 32 is in close contact with the end surface of the tip of the tooth 12 in the direction of the axis X, and the remaining part is connected to the end surface of the first sealing portion 31 in the direction of the axis X.

[0016] As shown in FIG. 2, the housing 6 is composed of a cylindrical body 61 that surrounds the iron core 10 radially outward, and a pair of lids 62 that are tightly attached to both end faces of the body 61 in the direction of the axis X.

[0017] The dimension of the body 61 in the direction of the axis X is set to be larger than the dimension of the iron core 10 in the direction of the axis X. The body 61 also has an inner circumferential surface 61i having an inner diameter dimension slightly smaller than the outer diameter dimension of the iron core 10, and the iron core 10 is fastened to the inner circumferential surface 61i along the axis X by press fitting or shrink fitting, etc. In this case, both end faces of the body 61 in the direction of the axis X are positioned so as to protrude outward in the direction of the axis X beyond the iron core 10.

[0018] The pair of lid portions 62 each have an attachment surface 62a that comes into close contact with the end surface of the corresponding side in the axial X direction of the body portion 61. In addition, the pair of lid portions 62 each have a contact surface (end surface) 62b that comes into close contact with the corresponding second sealing portion 32 over the entire circumference from the outside in the axial X direction when each attachment surface 62a is fixed to the end surface of the body portion 61 in the axial X direction.

[0019] As a result, annular spaces H1 and H2 are formed on both outer sides of the core 10 in the direction of the axis X, and are liquid-tightly sealed by the body 61, the pair of lid portions 62, and the pair of second sealing portions 32. As shown in Fig. 2, the spaces H1 and H2 communicate with each other via the flow paths defined in each slot S by the first sealing portions 31. In other words, the iron core 10 and the coil 20 wound around the iron core 10 are housed in a single sealed space made up of the spaces H1 and H2 and the flow paths in each slot S.

[0020] Furthermore, an inlet 6i connected to an external pump (not shown) is provided on the space H1 side of the body 61, allowing for the injection of a refrigerant such as oil. On the other hand, an outlet 6o is provided on the space H2 side of the body 61, allowing for the refrigerant in the space H2 to be discharged to the outside, and the outlet 6o is connected to a heat exchanger (not shown) that supplies the refrigerant to the external pump. This allows for the refrigerant to be filled and circulated within the sealed space that houses the coil 20, and therefore the electric motor 100 is configured to be able to cool the coil 20 within the sealed space.

[0021] The operation of the stator 1 and the electric motor 100 according to this embodiment configured as described above will be described below. In the following, a method for cooling the coil 20 provided in the stator 1 of the electric motor 100 will be described as an example.

[0022] To cool the coil 20, an external pump is first connected to the inlet 6i of the housing 6 of the electric motor 100, and a refrigerant is injected into the sealed space formed by the housing 6 and the iron core 10 and accommodating the coil 20. The injected refrigerant fills the space H1 and then flows into the space H2 through the flow paths formed in each slot S. The inflowing refrigerant then fills the space H2 and is sent to the external heat exchanger via the outlet 6o. The refrigerant sent to the heat exchanger is returned to the pump after its heat is removed, and is then injected again by the pump through the inlet 6i into the sealed space.

[0023] This allows the refrigerant to flow from the inlet 6i side toward the outlet 6o side within the sealed space that houses the coil 20 and is formed by the iron core 10 and the housing 6. In other words, by allowing the temperature-adjusted refrigerant to flow while contacting the coil 20 and the surfaces within each slot S, it is possible to recover heat generated in the coil 20 and the iron core 10, and to suppress excessive heat generation in the stator 1 and the electric motor 100.

[0024] 4, the first sealing portion 31 is formed to match the shape of the opening 14 of each slot S, thereby sealing each opening 14 without any gaps. This more reliably prevents the refrigerant for cooling the coil 20 from leaking from each slot S toward the rotor 5.

[0025] Furthermore, the second sealing portions 32 that seal between both end surfaces of the tip of each tooth 12 in the direction of the axis X and the contact surfaces 62b of the pair of cover portions 62 are formed integrally with the first sealing portions 31 that are fixed in close contact with the inside of each opening 14. Therefore, the bottom surfaces 32b of the second sealing portions 32 can be maintained in close contact with both end surfaces of the tip of each tooth 12 in the direction of the axis X.

[0026] Furthermore, by insert-molding the second sealing portion 32 into the first sealing portion 31, even if the dimensions of the teeth 12 in the direction of the axis X are uneven, as shown in Fig. 5, no gaps are formed between the teeth 12 and the second sealing portion 32. In other words, even if the bottom surface 32b of the second sealing portion 32 and some of the teeth 12 do not come into close contact with each other due to variations in the dimensions of the teeth 12 in the direction of the axis X, the resin material of the first sealing portion 31 can be poured into the gap.

[0027] As a result, the portions of the bottom surface 32b of the second sealing portion 32 that come into contact with both end surfaces of the teeth 12 in the axis X direction can prevent the refrigerant from leaking from the spaces H1, H2 due to their tight contact with each other. On the other hand, the portions of the bottom surface 32b of the second sealing portion 32 that do not come into contact with both end surfaces of the teeth 12 in the axis X direction can prevent the refrigerant from leaking from the spaces H1, H2 by being integrally connected with the resin material of the first sealing portion 31. In this way, by integrally forming the first sealing portion 31 and the second sealing portion 32 that seal the sealed space that houses the coil 20, the sealed space can be sealed more reliably, and leakage of the refrigerant to the outside can be prevented.

[0028] In this embodiment, the bottom surface 32b of the second sealing portion 32 is in direct contact with both end surfaces of the tip of each tooth 12 in the direction of the axis X. Alternatively, the resin material of the first sealing portion 31 may be continuously disposed in the circumferential direction around the axis X between the both end surfaces of the tip of each tooth 12 in the direction of the axis X and the second sealing portion 32. For example, as shown in Fig. 6, a recess 32c extending around the entire circumference may be provided in the bottom surface 32b of the second sealing portion 32. In this case, the second sealing portion 32 is insert-molded into the first sealing portion 31, so that the resin material of the first sealing portion 31 also fills the recess 32c.

[0029] That is, the second sealing portion 32 can be fixed in close contact with both end surfaces of the tip of each tooth 12 in the direction of the axis X, with the resin material of the first sealing portion 31 filled in the recesses 32c interposed therebetween. This allows for a more reliable sealing between the second sealing portion 32 and both end surfaces of each tooth 12 in the direction of the axis X. Furthermore, the contact area at the connection between the first sealing portion 31 and the second sealing portion 32 can be increased by the amount of the recesses 32c, thereby making the connection between the first sealing portion 31 and the second sealing portion 32 stronger.

[0030] 6, the recess 32c provided in the second sealing portion 32 may have a cross-sectional shape in which the opening of the recess 32c narrows, such as a dovetail groove shape, thereby improving the holding force that tightly contacts the first sealing portion 31 with the second sealing portion 32 against the contraction force that occurs when the resin hardens.

[0031] In this embodiment, for example, as shown in FIG. 7 , the bottom surface 32b of the second sealing portion 32 may be formed as a rough surface having irregularities of the same or greater magnitude as those of both end surfaces of each tooth 12 in the axial X direction. This creates a small gap between the bottom surface 32b and the opposing end surfaces of each tooth 12 due to the irregularities. Therefore, in this case, too, the resin material of the first sealing portion 31 can be disposed between the second sealing portion 32 and each tooth 12, ensuring more reliable adhesion between the two. Furthermore, by roughening the bottom surface 32b of the second sealing portion 32, the contact area with the resin material of the first sealing portion 31 is increased, thereby improving adhesion between the two. Furthermore, if the gaps formed by the irregularities of the rough surface are continuous in the circumferential direction, the resin material of the first sealing portion 31 filling the gaps is also continuously disposed in the circumferential direction, further improving sealing performance.

[0032] In the present embodiment, the first sealing portion 31 is formed by filling a resin material in a position that blocks the opening 14 of each slot S. Alternatively, the first sealing portion 31 may be formed to integrally cover the opening 14 of each slot S and the inner circumferential surface of the tip of each tooth 12. For example, the inner circumferential surface 31i of the first sealing portion 31 in the embodiment shown in FIG. 4 may be positioned radially inward of the inner circumferential surfaces of each tooth 12 within a range that does not contact the main body 51 of the rotor 5.

[0033] Furthermore, in this embodiment, the inner circumferential surface 32i and the outer circumferential surface 32o of the second sealing portion 32 on both sides in the thickness direction of the core 10 are disposed at the same radial positions as the inner circumferential surface 31i and the outer circumferential surface 31o of the first sealing portion 31, respectively. Alternatively, the radial position of the inner circumferential surface 32i of at least one second sealing portion 32 does not have to coincide with the inner circumferential surface 31i of the first sealing portion 31, as long as the bottom surface 32b of the second sealing portion 32 is connected to the end face of the first sealing portion 31 in the axial X direction. Similarly, the radial position of the outer circumferential surface 32o of at least one second sealing portion 32 does not have to coincide with the outer circumferential surface 31o of the first sealing portion 31, in the range where the bottom surface 32b of the second sealing portion 32 is connected to the end face of the first sealing portion 31 in the axial X direction.

[0034] In this embodiment, the first sealing portion 31 and the second sealing portion 32, which are made of different materials, are integrated by insert molding. Alternatively, the first sealing portion 31 and the second sealing portion 32 may be formed by integral molding using the same material.

[0035] In this case, the first sealing portion 31 and the second sealing portion 32 are formed as a single integrally molded product, eliminating the boundary between them, thereby more reliably sealing the enclosed space that houses the coil 20. Furthermore, an increase in the number of parts in the sealing member 30 can be suppressed, improving the manufacturability of the stator 1 and the electric motor 100 and reducing manufacturing costs.

[0036] In addition, in this embodiment, the first sealing portion 31 is formed from a resin material, but the material for forming the first sealing portion 31 is not limited to this. The material for the first sealing portion 31 can be selected arbitrarily as long as it can be filled in a position that closes each opening 14, conforming to the shape of the opening, and can be used to insert-mold the second sealing portion 32.

[0037] In addition, in this embodiment, the second sealing portion 32 is formed from a resin material different from that of the first sealing portion 31, but the material of the second sealing portion 32 is not limited to this. For example, the second sealing portion 32 may be formed from an elastically deformable material such as rubber or silicone, or a non-magnetic metal material such as stainless steel or an aluminum alloy. Furthermore, if the effect of the magnetic flux that drives the rotor 5 can be tolerated, a magnetic material may be used as the material of the second sealing portion 32.

[0038] 8, in the electric motor 100 according to this embodiment, a seal member 70 may be disposed between the contact surface 62b of the lid portion 62 of the housing 6 and the second sealing portion 32. In this case, for example, a groove 62g having a semicircular cross section and extending around the entire circumference is provided on the contact surface 62b of the lid portion 62. Similarly, a groove 32g having a semicircular cross section and extending around the entire circumference is provided on the surface of the second sealing portion 32 that comes into contact with the contact surface 62b.

[0039] As a result, a groove with a circular cross section extending around the entire circumference is formed between the contact surface 62b of the lid portion 62 and the second sealing portion 32, and a seal member 70 such as an O-ring can be fitted into the groove. This allows for a more reliable seal between the lid portion 62 and the second sealing portion 32. In the example shown in FIG. 8 , the grooves 62g and 32g are provided in both the lid portion 62 and the second sealing portion 32, respectively. Alternatively, if the seal member 70 can be disposed between the lid portion 62 and the second sealing portion 32, one of the grooves 62g and 32g may be omitted.

[0040] Furthermore, although the electric motor 100 according to this embodiment is exemplified as a rotary motor in which the rotor 5 is disposed radially inside the iron core 10 and rotates around the axis X, the electric motor 100 is not limited to this. For example, the electric motor 100 may be an outer rotor type in which the rotor 5 is disposed radially outside the iron core 10. Furthermore, the electric motor 100 may be a linear motor or the like that drives a mover in a direction along a predetermined axis.

[0041] In this embodiment, the inlet 6i and the outlet 6o are provided in the body portion 61 of the housing 6. Alternatively, both or either of the inlet 6i and the outlet 6o may be provided in the lid portion 62 of the housing 6.

[0042] Although the embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible to these embodiments without departing from the gist of the invention or the concept and spirit of the present invention derived from the content of the claims and their equivalents. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these.

[0043] The following supplementary notes are further disclosed regarding the above embodiment and modified examples. (Supplementary Note 1) A stator comprising: a core including a back yoke and a plurality of teeth protruding from the back yoke toward a mover and arranged at intervals along a drive direction of the mover; a plurality of coils wound around each of the teeth; and a sealing member that liquid-tightly seals each slot formed between adjacent teeth, the sealing member comprising: a first sealing portion disposed in a gap between the tips of the adjacent teeth; and a second sealing portion disposed on at least one side in the thickness direction of the teeth in a position that covers at least the tip-side end faces of all of the teeth in the thickness direction and the thickness-direction end faces of all of the first sealing portions, the second sealing portion being capable of being tightly fitted to a housing that accommodates the iron core and the coils, the first sealing portion and the second sealing portion being integrally formed. (Supplementary Note 2) A stator according to Supplementary Note 1, in which the first sealing portion covers the mover-side end face of each of the teeth. (Supplementary Note 3) The stator according to Supplementary Note 1 or Supplementary Note 2, wherein the back yoke is formed in a cylindrical shape with the axis line as a central axis and surrounding the mover that rotates about the axis line, each of the teeth protruding toward the mover in the radial direction, and the second sealing portion is formed in an annular shape centered on the axis line. (Supplementary Note 4) The stator according to any of Supplementary Note 1 to Supplementary Note 3, wherein the second sealing portion is integrated with the first sealing portion by insert molding. (Supplementary Note 5) The stator according to Supplementary Note 4, wherein the tooth-side end face of the second sealing portion is provided with a recess that is continuous along the driving direction. (Supplementary Note 6) The stator according to Supplementary Note 4, wherein the tooth-side end face of the second sealing portion is a rough surface having a plurality of concave and convex portions. (Supplementary Note 7) The stator according to any of Supplementary Note 1 to Supplementary Note 3, wherein the first sealing portion and the second sealing portion are formed by integral molding from the same material. (Supplementary Note 8) An electric motor comprising: the stator according to any one of Supplementary Note 1 to Supplementary Note 7; the mover arranged with a predetermined gap between it and the stator; and the housing that accommodates the iron core and the coil.(Appendix 9) The electric motor according to Appendix 8, wherein a groove is provided on at least one of an end surface of the second sealing portion that comes into close contact with the housing and an end surface of the housing that comes into close contact with the second sealing portion, in which a seal member that seals between the second sealing portion and the housing can be placed.

[0044] REFERENCE SIGNS LIST 1 stator 5 rotor (moving element) 6 housing 10 iron core 11 back yoke 12 teeth 20 coil 30 sealing member 31 first sealing portion 32 second sealing portion 32b bottom surface (end surface) 32c recess 32g groove 62b contact surface (end surface) 62g groove 70 sealing member 100 electric motor S slot X axis

Claims

1. A stator comprising: a back yoke, an iron core having a plurality of teeth protruding from the back yoke towards the movable member and arranged at intervals along the drive direction of the movable member; a plurality of coils wound around each of the teeth; and a sealing member that liquid-tightly seals each slot formed between adjacent teeth, the sealing member comprising: a first sealing portion arranged in the gap between the tips of adjacent teeth; and a second sealing portion arranged on at least one side of the teeth in the thickness direction, in a position that covers at least the thickness-wise end faces of the tip sides of all of the teeth and the thickness-wise end faces of all of the first sealing portions, and that can be tightly fitted to a housing that contains the iron core and the coils, wherein the first sealing portion and the second sealing portion are integrally formed.

2. The stator according to claim 1, wherein the first sealing portion covers the end face of each of the teeth on the mover side.

3. A stator as described in claim 1 or claim 2, wherein the back yoke is formed in a cylindrical shape with the axis as its central axis and surrounds the mover that rotates around the axis, each of the teeth protrudes radially toward the mover, and the second sealing portion is formed in an annular shape centered on the axis.

4. A stator according to any one of claims 1 to 3, wherein the second sealing portion is integrated with the first sealing portion by insert molding.

5. A stator according to claim 4, wherein a recess is provided on the end surface of the second sealing portion on the teeth side, the recess continuing along the driving direction.

6. A stator according to claim 4, wherein the end surface of the second sealing portion on the teeth side is a rough surface having a plurality of concave and convex portions.

7. A stator according to any one of claims 1 to 3, wherein the first sealing portion and the second sealing portion are formed by integral molding using the same material.

8. An electric motor comprising: a stator according to any one of claims 1 to 7; a mover arranged with a predetermined gap between it and the stator; and a housing that houses the iron core and the coil.

9. An electric motor as described in claim 8, wherein a groove is provided on at least one of the end face of the second sealing portion that comes into close contact with the housing and the end face of the housing that comes into close contact with the second sealing portion, in which a seal member that seals between the second sealing portion and the housing can be placed.

Images