Motor

Abstract

To provide a motor in which a stator core can be arranged easily without running on an R part formed in a housing.SOLUTION: In the motor in which the stator core and the rotor are accommodated in the housing, the housing includes an arc-shaped inner circumferential surface abutting on an outer circumferential surface of the stator core and a seating surface abutting on one end surface of the stator core, a rounded portion is formed at an intersection portion where the inner circumferential surface and the seating surface intersect, and the stator core includes a stepped portion accommodating the rounded portion at the intersection portion where the outer circumferential surface and the one end surface intersect.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a motor. [Background technology]

[0002] Conventionally, motors are used in, for example, electric compressors. The electric compressor includes a motor, a compression mechanism, and a housing that accommodates the motor and the compression mechanism. Patent Document 1 discloses that the housing is provided with a protrusion that abuts against the outer peripheral surface of a stator core that constitutes the motor, and an annular seating surface that abuts against one axial end face of the stator core, and that the housing and the stator core are fixed to each other by, for example, shrink fitting. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-011610 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-070583 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the shape accuracy of the housing produced by casting is not necessarily high, and the corner where the annular seating surface of the housing intersects with the protruding portion is rounded (hereinafter, sometimes referred to as an "R portion"), which causes one axial end face of the stator core to ride up on the R portion, resulting in a problem of reduced positioning accuracy of the stator core relative to the housing. In response to this, Patent Document 2 discloses an invention that solves the problem of riding up by forming a groove that gouges out the rounded portion formed in the housing. However, the technique disclosed in Patent Document 2 involves processing the housing, which is inefficient to work with, and therefore still poses a problem for practical use. [Means for solving the problem]

[0005] In order to solve such problems, the motor according to the present invention has the following configuration. In a motor in which a stator core and a rotor are accommodated in a housing, the housing has an arc-shaped inner peripheral surface that abuts against the outer peripheral surface of the stator core and a seating surface that abuts against one end face of the stator core, and an R portion is formed at the intersection where the inner peripheral surface and the seating surface intersect, and the stator core has a step portion that accommodates the R portion at the intersection where the outer peripheral surface and the one end face intersect. [Effects of the Invention]

[0006] According to the present invention having such characteristics, the stator core can be disposed without riding on the curved portion formed on the housing, thereby eliminating the problem of reduced accuracy in positioning the stator core relative to the housing. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view of an electric compressor according to an embodiment of the present invention. [Figure 2] Steel plates that make up the stator core. (A) Steel plate that abuts against the inner peripheral wall of the housing. (B) Steel plate on the housing seating surface side. [Figure 3] FIG. 2 is an enlarged view of a corner C between the stator core and the housing in FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Each drawing shows one embodiment of the present invention and is not intended to limit the present invention. In the following description, the same reference numerals in different drawings indicate parts with the same function, and duplicate explanations in each drawing will be omitted as appropriate. Furthermore, the dimensional relationships between elements in the drawings are for ease of understanding and are not intended to limit the actual dimensional ratios.

[0009] In this specification, "axial direction" refers to the longitudinal axis of the rotor 2, and "cross section" refers to a plane perpendicular to the longitudinal axis of the rotor 2, unless otherwise specified. "Radial direction" refers to the radial direction of the cross section, and "circumferential direction" refers to the circumferential direction of a circle centered on the rotation axis 2a of the rotor 2. "R portion" refers to a shape in which the corner is not at a 90-degree angle, and includes not only corners formed in a precisely arc-shaped form, but also arc-shaped forms with unevenness or corners cut obliquely. "R portion" also includes those formed intentionally and those formed accidentally.

[0010] As shown in FIG. 1, the motor 10 according to this embodiment is provided in an electric compressor 1 of a vehicle air conditioner, and is mainly composed of a stator core 3 and a rotor 2 provided in a housing 40.

[0011] The electric compressor 1 is a so-called inverter-integrated compressor, and includes a first housing 41 that houses the motor 10 and the inverter 30 for driving the motor 10, a second housing 42 that houses the compression mechanism 20 driven by the motor 10, an inverter cover 43, and a compression mechanism cover 44. These housings and covers (41, 42, 43, 44) are fastened together by fastening means (not shown) such as bolts to form a housing 40 of the electric compressor 1.

[0012] The first housing 41 is composed of an annular peripheral wall 41a and a partition wall 41b. The partition wall 41b forms a partition that divides the interior of the first housing 41 into a space that accommodates the motor 10 and a space that accommodates the inverter 30. The inverter 30 is accommodated in the first housing 41 through an opening on one end side (left side in FIG. 1) of the peripheral wall 41a, and this opening is closed by an inverter cover 43. The motor 10 is accommodated in the first housing 41 through an opening on the other end side (right side in FIG. 1) of the peripheral wall 41a, and this opening is closed by a second housing 42 (a bottom wall 42b described below). A cylindrical support portion 41b1 is provided in the radial center of the partition wall 41b and protrudes toward the other end side of the peripheral wall 41a to support one end of a rotating shaft 2a (described below) of the rotor 2.

[0013] Further, at the other end of the first housing 41, fastening portions (not shown) for fastening to the second housing 42 are formed at a plurality of locations spaced apart in the circumferential direction of the peripheral wall portion 41a.

[0014] Furthermore, protrusions 41f are formed at a plurality of locations spaced apart from one another in the circumferential direction on the peripheral wall of the first housing 41. Each of the protrusions 41f extends in the axial direction of the first housing 41.

[0015] A protruding end face (inner peripheral surface) 41f1 of the protruding portion 41f is formed in an arc shape (see FIG. 3) to match the shape of the outer peripheral surface 3e of the portion of the stator core 3 where a first steel plate 3g1 (described later) is laminated. In addition, a seating surface 41d that comes into contact with the stator core 3 is formed on one end side of the protruding end face 41f1.

[0016] The diameter of the inner circle along the protruding end surface 41f1 is formed to be smaller than the outer diameter of the outer peripheral surface 3e of the stator core 3 (specifically, the first steel plate 3g1) to be shrink-fitted, taking into account the shrink-fitting allowance. In this way, the stator core 3 and the housing 40 (first housing 41) are fixed by shrink fitting via the contact portion between the protruding end surface 41f1 of the protruding portion 41f and the outer circumferential surface 3e of the stator core 3.

[0017] The second housing 42 is fastened to the first housing 41 via fastening portions (not shown) formed at a plurality of locations spaced apart in the circumferential direction at an end of the first housing 41. The second housing 42 is formed, for example, in a cylindrical shape with one open end, that is, the side opposite the side fastened to the first housing 41, and the compression mechanism 20 is accommodated in the second housing 42 through this opening. The opening of the second housing 42 is closed by a compression mechanism cover 44.

[0018] The second housing 42 is composed of a cylindrical portion 42a and a bottom wall portion 42b on one end side of the cylindrical portion 42a, and the compression mechanism 20 is accommodated in a space defined by the cylindrical portion 42a and the bottom wall portion 42b. The bottom wall portion 42b forms a partition wall that separates the first housing 41 from the second housing 42. The bottom wall portion 42b has a through-hole in its radial center, through which the other end of the rotating shaft 2a of the rotor 2 is inserted, and a fitting portion into which a bearing 45 that supports the other end of the rotating shaft 2a is fitted.

[0019] Although not shown, the housing 40 is formed with a refrigerant intake port and a discharge port, and for example, the refrigerant drawn in through the intake port flows through the first housing 41 and is then drawn into the second housing 42. In this way, the motor 10 is cooled by the drawn refrigerant.

[0020] The compression mechanism 20 is driven by the motor 10 to compress the refrigerant, and is housed in the second housing 42 and disposed on the other end side of the rotary shaft 2 a of the rotor 2 . In this embodiment, the compression mechanism 20 is a scroll compressor and includes a fixed scroll 21 and a movable scroll 22. The movable scroll 22 is driven to orbit relative to the fixed scroll 21, thereby compressing the refrigerant. The refrigerant compressed by the compression mechanism 20 is discharged from a discharge port.

[0021] 1, the motor 10 is configured to include a rotor 2 having a plurality of magnetic poles (not shown), an annular stator core 3 arranged radially outward of the rotor 2, an electrically insulating bobbin 4 arranged at an end of the stator core 3, and a coil 5 wound around the bobbin 4 and the stator core 3, and is, for example, a three-phase AC motor. For example, a direct current from a vehicle battery (not shown) is converted into an alternating current by an inverter 30 and supplied to the motor 10.

[0022] In this embodiment, the rotor 2 has four N-pole permanent magnets and four S-pole permanent magnets embedded therein, for a total of eight magnetic poles spaced at equal intervals.

[0023] Next, the shapes of the stator core 3 and the steel plates 3g (3g1, 3g2) according to the embodiment of the present invention will be described in detail with reference to FIGS.

[0024] In this embodiment, the stator core 3 is configured by laminating two types of electrically insulated thin ferromagnetic steel plates 3g (3g1, 3g2). Most of the steel plates 3g are first steel plates 3g1, with only a small amount being second steel plates 3g2. The second steel plates 3g2 are concentrated on one end side.

[0025] The thickness of one steel plate 3g (3g1, 3g2) is generally 0.2 mm to 1.0 mm. The steel plates 3g (3g1, 3g2) are generally made by stamping a strip-shaped electromagnetic steel plate into a circular shape corresponding to the shape of the stator core 3 using a press, so the made steel plates 3g (3g1, 3g2) have high dimensional accuracy. The lamination is performed by methods such as adhesive lamination, pin riveting lamination, dowel riveting lamination, and laser welding lamination.

[0026] As shown in FIG. 2, each steel plate 3g (3g1, 3g2) has 12 teeth 3b and 12 slots 3c arranged alternately at equal intervals in the circumferential direction, and is composed of a first back yoke 3a1 and a second back yoke 3a2 that form the outer periphery of the steel plate 3g (3g1, 3g2). The width 3r2 of the second back yoke 3a2 is narrower than the width 3r1 of the first back yoke 3a1. As shown by the dotted line in FIG. 2, the inner diameters of the first back yoke 3a1 and the second back yoke 3a2 are equal. As a result, the diameter 3d1 of the first steel plate 3g1 and the diameter 3d2 of the second steel plate 3g2 differ in length by twice the difference between the width 3r1 of the first back yoke 3a1 and the width 3r2 of the second back yoke 3a2. The other shapes and thicknesses are the same. Each steel plate 3g (3g1, 3g2) is stacked with the teeth 3b and slots 3c aligned, so that the stator core 3 as a whole has a structure with 12 teeth 3b and 12 slots 3c alternately and evenly spaced in the circumferential direction.

[0027] 3, the second steel plate 3g2 having a smaller diameter is laminated on one end face side of the housing 40 where the seating surface 41d is located. A plurality of second steel plates 3g2 are laminated so as to have a thickness equal to or greater than the radius of the R portion 41r. Depending on the radius of the R portion 41r and the thickness of each second steel plate 3g2, for example, 1 to 10 second steel plates 3g2, and preferably 3 to 4 second steel plates 3g2 are laminated. Therefore, an annular step portion 3f is formed on one end face side of the stator core 3 due to the difference in diameter between the steel plates 3g (3g1, 3g2).

[0028] The second steel plate 3g2 is fabricated with a radius of curvature equal to or greater than a predetermined radius of curvature of the R portion 41r, but smaller than that of the first steel plate 3g1. The predetermined radius of curvature of the R portion 41r can be, for example, a value obtained by adding a predetermined margin to a previously measured maximum value or an empirically determined value. Specifically, the radius is set to be smaller than that of the first steel plate 3g1 by, for example, 0.25 mm or more. The predetermined radius of curvature of the R portion 41r is equal to or smaller than the radial length of the seating surface 41d.

[0029] As a result, the rounded portion 41r formed on the housing 40 fits into the gap between the stepped portion 3f of the stator core 3 and the housing 40, so the stator core 3 can abut against the inner circumferential surface 41f1 and the seating surface 41d of the housing 40 (first housing 41) without riding up on the rounded portion 41r. Moreover, the second steel plate 3g2 only needs to have a slightly smaller diameter than the first steel plate 3g1, and the number of layers of the second steel plate 3g2 can be extremely small (for example, 3 to 4 sheets), so the electromagnetic influence on the entire stator core 3 can be kept to a negligible level.

[0030] Furthermore, the second steel plate 3g2 can be mass-produced easily by press working in the same way as the first steel plate 3g1 if a small diameter mold is prepared in advance, which is also excellent in terms of workability.

[0031] As described above, the stator core constituting the motor according to the present invention is formed with a small diameter on the one end face side where the seating surface of the housing is located, so that the stator core can be installed in the housing without riding over the rounded corners (R portions) formed during casting of the housing. Furthermore, the diameter of the stator core can be made small by laminating steel plates of small diameter, and this can be achieved by ordinary press working, making it suitable for mass production. Furthermore, since the rounded corners are usually only a few hundred microns in size, the steps can be small and the electromagnetic effects are negligible, so there is no particular impact on the motor's functionality.

[0032] The embodiments of the present invention have been described in detail above with reference to the drawings. However, the configuration of the present invention is not limited to the described embodiments, and the present invention also includes design changes and the like within the scope of the gist of the present invention. [Explanation of symbols]

[0033] 1: electric compressor, 2: rotor, 2a: rotating shaft, 3: stator core, 3a1: first back yoke, 3a2: second back yoke, 3b: Teeth, 3c: Slot, 3d1,3d2: Diameter, 3e: Outer surface, 3f: Step part, 3g: steel plate, 3g1: first steel plate, 3g2: second steel plate, 3r1,3r2: width, 4: bobbin, 5: coil, 10: motor, 20: Compression mechanism, 21: Fixed scroll, 22: Orbiting scroll, 30: Inverter, 40: Housing, 41: first housing, 41a: peripheral wall portion, 41b: partition wall portion, 41b1: support portion, 41d: seating surface, 41f: protruding portion, 41f1: protruding end surface (inner peripheral surface), 41r: R portion, 42: second housing, 42a: cylindrical portion, 42b: bottom wall portion, 43: Inverter cover, 44: Compression mechanism cover, 45: Bearing

Claims

1. In a motor in which a stator core and a rotor are housed in a housing, The housing includes: The rotor has an arc-shaped inner peripheral surface that contacts the outer peripheral surface of the stator core, and a seating surface that contacts one end surface of the stator core, an R portion is formed at an intersection where the inner circumferential surface and the seating surface intersect; The stator core is A step portion for accommodating the R portion is provided at the intersection where the outer circumferential surface and the one end surface intersect. A motor characterized by:

2. The stator core is formed by laminating a plurality of two types of steel plates, The step portion is formed by stacking one steel plate and another steel plate having a smaller radius of the outer circumferential surface than the other steel plate.

2. The motor according to claim 1.

3. The radius of the outer peripheral surface of the other steel plate is shorter than the radius of the inner peripheral surface by the radius of curvature of the R portion or more.

3. The motor according to claim 2.

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