Stator and motor

Abstract

A stator (20) comprises: a stator core (21) having an annular-shaped annular portion (21a) and a plurality of teeth (21b) in a circumferential direction which extend radially inward from the annular portion; a winding (23) wound around the teeth; and a mold resin (24) that seals the winding protruding from an axial end portion (21c) of the stator core while being formed in an annular shape so as to cover the axial end portion of the stator core. An outer peripheral surface (21d) of the annular portion has a recess (21e) that is recessed radially inward while extending in the axial direction from an axial end portion of the stator core. An outer peripheral surface (24a) of the mold resin has a resin recess (24b) that is recessed radially inward so as not to overlap the recess when viewed in the axial direction.

Description

Stator and motor CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2023-209469, filed on December 12, 2023, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a stator and a motor.

[0003] Conventionally, a motor stator includes a stator core, windings, and a molded resin (see, for example, Patent Document 1). This stator core has an annular portion and a plurality of circumferential teeth extending radially inward from the annular portion. The windings are wound around the teeth. The molded resin is formed in an annular shape to cover the axial end of the stator core and seals the windings protruding from the axial end of the stator core, i.e., the coil ends. Such a stator can, for example, prevent coil end displacement and ensure insulation of the coil ends.

[0004] Also, some stator cores have recesses on the outer peripheral surface of the annular portion (see, for example, Patent Document 2). The recesses are provided, for example, in circumferential positions where the teeth are provided and have little effect on the magnetic circuit. A stator using such a stator core can, for example, be made lighter.

[0005] JP 2022-184651 A Patent No. 7026811 A

[0006] When molding a molded resin around a stator core having a recessed portion as described above using a mold die, the outer diameter of the molded resin needs to be reduced to prevent the molten resin from flowing into the recessed portion. If the molten resin flows into the recessed portion, it will leak radially outward from the recessed portion, causing a portion of the molded resin to protrude radially outward from the annular portion. This can result in, for example, a decrease in the fixing strength due to a portion of the molded resin getting between the housing and the annular portion, which are fixed to the outer peripheral surface of the annular portion by shrink fitting. Furthermore, if the outer diameter of the molded resin is reduced, the housing member including the windings sealed in the molded resin can only be sealed within a narrow area. Furthermore, if the outer diameter of the molded resin is reduced, the housing member including the windings sealed in the molded resin cannot be securely sealed.

[0007] In a first aspect of the present disclosure, the stator includes a stator core having an annular portion and a plurality of teeth extending radially inward from the annular portion and arranged circumferentially, windings wound around the teeth, and a molded resin formed in an annular shape so as to cover an axial end of the stator core and seal the windings protruding from the axial end of the stator core, wherein an outer peripheral surface of the annular portion has a recessed portion extending axially from the axial end of the stator core and recessed radially inward, and an outer peripheral surface of the molded resin has a resin recessed portion recessed radially inward so as not to overlap with the recessed portion when viewed in the axial direction.

[0008] According to this configuration, the outer peripheral surface of the molded resin has a resin recess recessed radially inward so as not to overlap the recess of the annular portion when viewed in the axial direction. This prevents the molten resin from flowing into the recess when pouring the molten resin using a molding die. This prevents the molten resin from leaking radially outward from the recess, thereby preventing a portion of the molded resin from spilling radially outward from the annular portion. As a result, for example, it is possible to prevent a decrease in the fixing strength due to a portion of the molded resin getting between the housing and the annular portion, which are fixed to the outer peripheral surface of the annular portion by shrink fitting. Furthermore, the outer peripheral surface of the molded resin can be enlarged radially outward at circumferential positions where the resin recess is not formed. Therefore, for example, the housing member including the winding sealed in the molded resin can be sealed over a wide area, even radially outward, and securely sealed.

[0009] In a second aspect of the present disclosure, a motor includes the stator and a rotor rotatably supported and disposed opposite the tips of the teeth. With this configuration, the above-described effects can be obtained in the motor.

[0010] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is a schematic diagram of a motor according to one embodiment, Fig. 2 is a perspective view of a split core according to one embodiment, Fig. 3 is a partially enlarged plan view of a stator according to one embodiment, Fig. 4 is a partially enlarged plan view of the stator according to one embodiment, and Fig. 5 is a partially cross-sectional view of the stator according to one embodiment.

[0011] An embodiment will be described below with reference to the drawings. Note that for the sake of convenience, some components may be exaggerated or simplified in the drawings. Furthermore, the dimensional proportions of each component may differ from those of the actual components.

[0012] (Configuration of Motor 10) As shown in Fig. 1, motor 10 includes a stator 20 and a rotor 30. Motor 10 also includes a first inverter circuit and a second inverter circuit (not shown) that are capable of independently generating three-phase AC currents that are 120 degrees out of phase with each other. For example, the first inverter circuit can generate a first system of three-phase AC currents with X, Y, and Z phases. The second inverter circuit can generate a second system of three-phase AC currents with U, V, and W phases.

[0013] (Configuration of Stator 20) As shown in FIG. 3 , the stator 20 includes a stator core 21, insulators 22, windings 23, and molded resin 24. Note that FIGS. 1 and 3 schematically illustrate cross sections of the insulators 22 and the windings 23. The stator core 21 is made up of a plurality of split cores 25 (see FIG. 2 ) split in the circumferential direction. In this embodiment, the stator core 21 is made up of 12 split cores 25. The stator core 21 has an annular portion 21 a and a plurality of teeth 21 b extending radially inward from the annular portion 21 a and aligned in the circumferential direction. One tooth 21 b is provided for each split core 25. The insulators 22 are attached so as to cover the teeth 21 b. The windings 23 are wound around the teeth 21 b via the insulators 22 in a concentrated winding manner.

[0014] (Detailed Configuration of Winding 23) The winding 23 has a plurality of first system windings 41 to which a first system of three-phase AC current having X, Y, and Z phases is supplied, and a plurality of second system windings 42 to which a second system of three-phase AC current having U, V, and W phases is supplied. The first system windings 41 and the second system windings 42 are arranged alternately in the circumferential direction. That is, the winding 23 has six first system windings 41, X+, X-, Y+, Y-, Z+, and Z-. The winding 23 also has six second system windings 42, U+, U-, V+, V-, W+, and W-. Note that + and - indicate forward and reverse winding.

[0015] For example, as shown in FIG. 1, the windings 23 are arranged such that the first system windings 41 and the second system windings 42 are alternately arranged in the circumferential direction in the order of Z+, W-, Y-, V+, X+, U-, Z-, W+, Y+, V-, X-, U+.

[0016] 5, the stator 20 includes a first neutral point terminal 50 and a second neutral point terminal 60. (Configuration of the first neutral point terminal 50 and the second neutral point terminal 60) The first neutral point terminal 50 and the second neutral point terminal 60 are made of a conductive metal material and are circular. In this embodiment, the first neutral point terminal 50 and the second neutral point terminal 60 are formed in a perfect circular shape.

[0017] The first neutral point terminal 50 and the second neutral point terminal 60 are disposed at positions offset in the axial direction with respect to the coil ends 23a of the windings 23 protruding from the axial end portions 21c of the stator core 21. The first neutral point terminal 50 and the second neutral point terminal 60 are disposed at different axial positions. The first neutral point terminal 50 and the second neutral point terminal 60 of this embodiment have a plurality of connection portions 50a, 60a that rise axially from the annular portion and are aligned in the circumferential direction.

[0018] A first neutral conductor 41a, which is one terminal wire of the first system winding 41, is connected to the connection portion 50a of the first neutral terminal 50. A second neutral conductor (not shown), which is one terminal wire of the second system winding 42, is connected to the connection portion 60a of the second neutral terminal 60. Note that Fig. 5 schematically illustrates the state in which one first neutral conductor 41a is connected to one connection portion 50a of the first neutral terminal 50, but does not illustrate the state in which the second neutral conductor is connected to the connection portion 60a of the second neutral terminal 60.

[0019] The other terminal wire of the first system winding 41, that is, a first power supply wire 41b, is routed circumferentially at a position offset in the axial direction from the coil end 23a and then drawn out axially to be connected to a first inverter circuit (not shown). The other terminal wire of the second system winding 42, that is, a second power supply wire 42a, is routed circumferentially at a position offset in the axial direction from the coil end 23a and then drawn out axially to be connected to a second inverter circuit (not shown). Note that Fig. 5 shows two first power supply wires 41b routed circumferentially and one second power supply wire 42a routed circumferentially.

[0020] (Configuration of molded resin 24) The molded resin 24 is formed in an annular shape to cover the axial end 21c of the stator core 21, and seals the coil ends 23a of the windings 23 protruding from the axial end 21c of the stator core 21. More specifically, the molded resin 24 seals the accommodating member including the coil ends 23a. In addition to the coil ends 23a, the accommodating member includes, for example, the first neutral point terminal 50 and the second neutral point terminal 60, the first power supply wire 41b routed in the circumferential direction, the second power supply wire 42a routed in the circumferential direction, and components (not shown) that maintain the spacing between them.

[0021] The molded resin 24 is formed using a mold (not shown) by pouring molten resin into a mold fixed to the stator core 21 and allowing the molten resin to harden.

[0022] The annular portion 21a of the stator core 21 in the stator 20 configured as described above is fixed to a cylindrical housing 70. The housing 70 of this embodiment is fixed to the outer peripheral surface 21d of the annular portion 21a by shrink fitting.

[0023] 3 and 4, the outer peripheral surface 21d of the annular portion 21a of the stator core 21 has a recess 21e that extends axially from the axial end 21c of the stator core 21 and is recessed radially inward. The recess 21e is located in a region that has little effect on the magnetic circuit and is provided at a circumferential position where the teeth 21b are provided. More specifically, the recess 21e is provided at the center of the circumferential position where the teeth 21b are provided. Furthermore, the recess 21e in this embodiment is formed in a substantially rectangular shape when viewed in the axial direction of the stator 20.

[0024] 2, the recesses 21e of this embodiment are formed at both axial ends of the stator core 21. That is, the recesses 21e of this embodiment are not formed in the axial center of the stator core 21.

[0025] As shown in FIGS. 3 and 4, the outer peripheral surface 24a of the molded resin 24 has a resin recess 24b recessed radially inward when viewed in the axial direction of the stator 20 so as not to overlap the recess 21e.

[0026] As shown in Fig. 4, the outermost diameter portion of the molded resin 24 is located radially outward from the radial position of the bottom of the recess 21e. In Fig. 4, the radial position of the outermost diameter portion of the molded resin 24 is schematically illustrated by a two-dot chain line. The outermost diameter portion of the molded resin 24 is located radially inward from the outermost diameter portion of the annular portion 21a.

[0027] Resin recess 24b is provided so that molded resin 24 is spaced a certain distance or more from recess 21e when viewed in the axial direction of stator 20. In other words, resin recess 24b is provided so that axial end 21c of stator core 21 is connected and exposed around the entire circumference on the radially outer side of stator core 21 when viewed in the axial direction of stator 20. Note that axial end 21c that is connected and exposed around the entire circumference of stator core 21 is the surface that comes into contact with a molding die used to mold molded resin 24.

[0028] 1, the rotor 30 is disposed radially inside the stator 20 so as to face the tips of the teeth 21b, and is rotatably supported. The rotor 30 has a plurality of permanent magnets (not shown) arranged in the circumferential direction.

[0029] (Operation of the embodiment) Next, the operation of the motor 10 configured as described above will be described. The motor 10 includes a first inverter circuit and a second inverter circuit. The windings 23 of the stator 20 include a plurality of first system windings 41 to which a first system of three-phase AC current is supplied from the first inverter circuit, and a plurality of second system windings 42 to which a second system of three-phase AC current is supplied from the second inverter circuit. Therefore, the motor 10 can be driven by at least one of the first system windings 41 and the second system windings 42, providing redundancy.

[0030] The molded resin 24 is formed in an annular shape to cover the axial end 21c of the stator core 21, and seals the windings 23, i.e., the coil ends 23a, protruding from the axial end 21c of the stator core 21. This prevents the coil ends 23a from displacing and ensures insulation of the coil ends 23a. Furthermore, the outer peripheral surface 21d of the annular portion 21a of the stator core 21 has recesses 21e, which allows the stator 20 to be made lighter, for example.

[0031] (Advantages of the Embodiment) Next, advantages of the above-described embodiment are described below. (1) The outer peripheral surface 24a of the molded resin 24 has a resin recess 24b recessed radially inward so as not to overlap the recess 21e of the annular portion 21a when viewed in the axial direction. Therefore, when molten resin is poured into the molded resin 24 using a mold, the molten resin is prevented from flowing into the recess 21e of the annular portion 21a. This prevents the molten resin from leaking radially outward from the recess 21e, thereby preventing a portion of the molded resin 24 from protruding radially outward from the annular portion 21a. As a result, for example, a decrease in the fixing strength due to a portion of the molded resin 24 entering between the housing 70 and the annular portion 21a, which are fixed to the outer peripheral surface 21d of the annular portion 21a by shrink fitting, can be prevented. Furthermore, the outer peripheral surface 24a of the molded resin 24 can be enlarged radially outward at circumferential positions where the resin recess 24b is not formed. Therefore, for example, the windings 23 sealed in the mold resin 24, specifically the housing member including the coil ends 23a, can be sealed over a wide range, even partially outward in the radial direction, and can be sealed firmly. Specifically, the housing members such as the coil ends 23a, the first neutral terminal 50 and the second neutral terminal 60, the first power supply wire 41b routed in the circumferential direction, the second power supply wire 42a routed in the circumferential direction, and components (not shown) that maintain the spacing therebetween can be sealed firmly.

[0032] (2) The outermost diameter portion of the molded resin 24 is set radially outward from the radial position of the bottom of the recess 21e, so that the accommodating member including the coil end 23a can be partially sealed over a wider range, extending radially outward, and more firmly sealed.

[0033] (3) Because the outermost diameter portion of the molded resin 24 is located radially inward of the outermost diameter portion of the annular portion 21a, when the molten resin is poured using a molding die, the molten resin is prevented from leaking radially outward from the outermost diameter portion of the annular portion 21a. This prevents a portion of the molded resin 24 from spilling radially outward from the annular portion 21a. As a result, for example, a decrease in the fixing strength due to a portion of the molded resin 24 getting between the housing 70 and the annular portion 21a, which are fixed to the outer peripheral surface 21d of the annular portion 21a by shrink fitting, can be prevented.

[0034] (4) The windings 23 include a plurality of first system windings 41 supplied with current from the first system and a plurality of second system windings 42 supplied with current from the second system. Therefore, for example, the number of components to be sealed in the molded resin 24 tends to increase, such as the need for the respective neutral terminals, i.e., the first neutral terminal 50 and the second neutral terminal 60, and components (not shown) that maintain the spacing between them. Therefore, the effect of this embodiment, in which the housing members can be partially sealed over a wide range, even radially outward, is more effective.

[0035] (Modifications) This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0036] In the above embodiment, the outermost diameter portion of the molded resin 24 is set radially outward from the radial position of the bottom of the recess 21 e, but this is not limited to this. That is, the outermost diameter portion of the molded resin 24 may be set at the same radial position as the radial position of the bottom of the recess 21 e, or may be set radially inward from the radial position of the bottom of the recess 21 e.

[0037] In the above embodiment, the outermost diameter portion of the molded resin 24 is located radially inward of the outermost diameter portion of the annular portion 21 a, but this is not limiting. For example, the outermost diameter portion of the molded resin 24 may be located at the same radial position as the outermost diameter portion of the annular portion 21 a.

[0038] In the above embodiment, the windings 23 include a plurality of first system windings 41 to which a first system current is supplied and a plurality of second system windings 42 to which a second system current is supplied. However, this is not limiting. For example, the stator 20 may be configured to include only windings 23 to which a single system current is supplied.

[0039] In the above embodiment, the recess 21 e is formed in a substantially rectangular shape when viewed in the axial direction of the stator 20, but is not limited thereto and may be formed in another shape. Also, the resin recess 24 b may be formed in another shape as long as the mold resin 24 is provided so as to be spaced apart from the recess 21 e by a certain distance or more when viewed in the axial direction of the stator 20.

[0040] In the above embodiment, the recess 21e is provided at the center position of the circumferential position where the tooth 21b is provided, but this is not limited to this and the recess 21e may be provided at a different position, or multiple recesses may be provided for one tooth 21b.

[0041] In the above embodiment, the recesses 21 e are provided at both axial ends of the stator 20. However, this is not limiting. For example, the recesses 21 e may be provided on the outer peripheral surface 21 d of the annular portion 21 a over the entire axial length of the stator core 21.

[0042] In the above embodiment, the stator core 21 is made up of the plurality of split cores 25. However, the present invention is not limited to this. That is, the stator core 21 may have an annular portion 21a that is connected around the entire circumference.

[0043] In the above embodiment, the stator 20 has twelve teeth 21b. However, the present invention is not limited to this and the stator 20 may have another number of teeth 21b, such as twenty-four.

[0044] In the above embodiment, the housing 70 is fixed to the outer circumferential surface 21d of the annular portion 21a by shrink fitting. However, the present invention is not limited to this and the housing 70 may be fixed by other means.

[0045] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

[0046] The features of the present invention are as follows: [1] A stator (20) including a stator core (21) having an annular portion (21a) and a plurality of teeth (21b) extending radially inward from the annular portion and arranged in a circumferential direction, windings (23) wound around the teeth, and a molded resin (24) formed in an annular shape so as to cover an axial end of the stator core and sealing the windings protruding from the axial end of the stator core, wherein an outer peripheral surface (21d) of the annular portion has a recess (21e) extending axially from the axial end (21c) of the stator core and recessed radially inward, and an outer peripheral surface (24a) of the molded resin has a resin recess (24b) recessed radially inward so as not to overlap with the recess when viewed in the axial direction.

[0047] [2] The stator according to the above [1], wherein the outermost diameter portion of the molded resin is set radially outward from the radial position of the bottom of the recess. [3] The stator according to the above [1] or [2], wherein the outermost diameter portion of the molded resin is set radially inward from the outermost diameter portion of the annular portion.

[0048] [4] The stator according to any one of [1] to [3], wherein the windings include a plurality of first system windings (41) to which a first system current is supplied, and a plurality of second system windings (42) to which a second system current is supplied.

[0049] [5] A motor (10) comprising the stator described in any one of [1] to [4] above, and a rotor (30) rotatably supported and arranged to face the tips of the teeth.

Claims

1. A stator (20) comprising: a stator core (21) having a circular annular portion (21a) and a plurality of teeth (21b) extending radially inward from the annular portion and arranged circumferentially; windings (23) wound around the teeth; and molded resin (24) formed in an annular shape so as to cover the axial end (21c) of the stator core and sealing the windings protruding from the axial end of the stator core, wherein an outer peripheral surface (21d) of the annular portion has a recess (21e) extending axially from the axial end of the stator core and recessed radially inward, and an outer peripheral surface (24a) of the molded resin has a resin recess (24b) recessed radially inward so as not to overlap with the recess when viewed in the axial direction.

2. The stator according to claim 1, wherein an outermost diameter portion of the molding resin is set radially outward from a radial position of a bottom of the recess.

3. The stator according to claim 1, wherein an outermost diameter portion of the molding resin is set radially inward of an outermost diameter portion of the annular portion.

4. The stator according to claim 1, wherein the windings include a plurality of first system windings (41) to which a first system current is supplied, and a plurality of second system windings (42) to which a second system current is supplied.

5. A motor (10) comprising a stator according to any one of claims 1 to 4, and a rotor (30) rotatably supported and arranged to face the tips of the teeth.

Images