Electric compressor motor

Abstract

[Problem] Electric compressor motors have had, for example, the problem that, when fixing a housing and a stator by shrink-fitting, an overly strong pressure causes an excessive force to be applied, thereby deforming the stator or causing a gap (air gap) between the stator and a rotor not to be in conformance with the design specification. [Solution] An electric compressor motor comprising a stator and a rotor in a housing, said electric compressor motor being characterized in that: the housing is provided with a recess in an inner wall of a protruding part that protrudes radially inward; the stator is provided with, on an outer peripheral surface thereof, a protrusion that corresponds to the recess; and the protrusion and the recess are fixed by shrink-fitting.

Description

Electric compressor motor

[0001] The present invention relates to a motor for an electric compressor.

[0002] Conventionally, an electric compressor includes a compressor motor having a stator and a rotor, a compression mechanism, and a housing that accommodates the compressor motor and the compression mechanism. The housing and the stator are fixed by shrink fitting (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2005-214160

[0004] However, when fixing the housing and stator by shrink fitting, if the tightening is too strong, excessive force is applied, causing problems such as deformation of the stator or the gap between the stator and rotor (air gap) deviating from the design specifications.

[0005] In order to solve the above problems, the present invention provides a motor for an electric compressor having the following configuration: An electric compressor motor including a stator and a rotor housed within a housing, wherein the housing has a recess on the inner wall of a protrusion that protrudes radially inward, the stator has a protrusion on its outer peripheral surface that corresponds to the recess, and the protrusion is fixed in the recess by shrink fitting.

[0006] According to the present invention having such characteristics, it is possible to reduce the excessive force that is applied when fixing the housing and the stator by shrink fitting, thereby eliminating problems such as deformation of the stator and misalignment of the air gap.

[0007] FIG. 1 is a cross-sectional view of an electric compressor according to an embodiment of the present invention. FIG. 2 is a perspective view of the cross-sectional portion indicated by A-A in FIG. 1 in the electric compressor according to an embodiment of the present invention, viewed obliquely from above (with the rotor removed). FIG. 3 is an exploded perspective view of a stator and a first housing. FIG. 4 is a diagram showing forces acting on a stator during shrink fitting in a conventional configuration. FIG. 5 is a diagram showing forces acting on a stator during shrink fitting in a configuration according to an embodiment of the present invention. FIG. 6 is a diagram showing shapes of a housing protrusion and a stator according to an embodiment of the present invention. FIG. 7 is a perspective view showing the shape of a recess in a housing protrusion according to an embodiment of the present invention.

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Each drawing illustrates an 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 descriptions in each drawing will be omitted as appropriate. The dimensional relationships between elements in the drawings are for ease of understanding and are not intended to limit the actual dimensional ratios. In this specification, the term "axial direction" refers to the longitudinal axis direction of the rotor 2, and the term "cross section" refers to a plane perpendicular to the longitudinal axis direction of the rotor 2, unless otherwise specified. The term "radial direction" refers to the radial direction of the cross section, and the term "circumferential direction" refers to the circumferential direction of a circle centered on the rotation axis 2a of the rotor 2.

[0009] As shown in FIG. 1 , the electric compressor 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 3 and a rotor 2 provided within a housing 40.

[0010] The electric compressor 1 is a so-called inverter-integrated compressor, and includes a first housing 41 that houses the electric compressor motor 10 and the inverter 30 for driving the electric compressor motor 10, a second housing 42 that houses the compression mechanism 20 driven by the electric compressor motor 10, an inverter cover 43, and a compression mechanism cover 44. These housings and covers (41, 42, 43, 44) are fastened together with fastening means (not shown) such as bolts to form the housing 40 of the electric compressor 1.

[0011] The first housing 41 is composed of an annular peripheral wall 41a and a partition wall 41b. The partition wall 41b forms a partition wall that divides the first housing 41 into a space that accommodates the electric compressor 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 electric compressor 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 (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.

[0012] As shown in FIG. 2, fastening portions 41c (bosses) for fastening to the second housing 42 are formed at multiple locations (six locations) at the other end of the first housing 41, spaced apart in the circumferential direction of the peripheral wall portion 41a.

[0013] Furthermore, protrusions 41f are formed on the peripheral wall 41a of the first housing 41 at eight locations that are circumferentially spaced apart and offset from the circumferential angular positions at which the fastening portions 41c are formed. Four of the eight protrusions 41f are provided at equal intervals between the three fastening portions 41c located on the upper side of Fig. 2. The remaining four protrusions 41f are provided at equal intervals between the three fastening portions 41c located on the lower side of Fig. 2. Each protrusion 41f is formed to protrude radially inward from the fastening portions 41c and extends in the axial direction of the first housing 41.

[0014] More specifically, as shown in FIG. 2, the protruding end faces (inner peripheral surfaces) 41f1 of the protruding portions 41f are formed in an arc shape to match the shape of the outer peripheral surface of the stator 3 (more specifically, the back yoke 3a) of the motor 10 for an electric compressor, and there is a gap between the inner diameter circle along each protruding end face 41f1 and the inner surface of the fastening portion 41c.

[0015] As shown in FIG. 3 , each protrusion 41f is provided with a recess 41n extending from one axial end (toward the inverter 30) to the other axial end (toward the compression mechanism 20). It is particularly preferable that the recess 41n be provided in the circumferential center. It is also preferable that the recess 41n be formed over the entire axial length of the protrusion 41f. A protrusion 3n is formed on the stator 3 corresponding to the recess 41n. In this specification, the phrase "protrusion 3n corresponding to the recess 41n" refers to a relationship in which the recess 41n and the protrusion 3n are aligned with each other and the protrusion 3n is sandwiched between them when shrink-fitted.

[0016] Taking into consideration the shrink-fitting allowance, the diameter of the inner diameter circle along the protruding end surface 41f1 is formed to be smaller than the outer diameter of the outer peripheral surface of the stator 3 to be shrink-fitted. In this way, the stator 3 and the housing 40 (first housing 41) are fixed by shrink-fitting via the recessed portion 41n and the protruding portion 3n in addition to the contact portion between the protruding end surface 41f1 of the conventional protruding portion 41f and the outer peripheral surface of the stator 3.

[0017] The second housing 42 is fastened to the first housing 41 via fastening portions 41c formed at a plurality of circumferentially spaced locations on 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, an open end 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 thereof, 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 suction port flows through the first housing 41 and is then drawn into the second housing 42. In this way, the electric compressor motor 10 is cooled by the drawn refrigerant.

[0020] The compression mechanism 20 is driven by the electric compressor 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 2a 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 refrigerant is compressed by the movable scroll 22 being driven to orbit relative to the fixed scroll 21. The refrigerant compressed by the compression mechanism 20 is discharged from a discharge port.

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

[0022] In this embodiment, four permanent magnets with north poles and four permanent magnets with south poles are embedded in the rotor 2, resulting in eight magnetic poles spaced at equal intervals. Also, in this embodiment, the stator 3 has 12 teeth 3b and 12 slots 3c arranged alternately at equal intervals, as shown in FIG.

[0023] Next, the effect of the motor 10 for an electric compressor according to this embodiment of the invention of mitigating excessive force acting on the stator 3 during shrink fitting will be described.

[0024] Conventionally, when the housing 40 and the stator 3 are shrink-fitted, the stator 3 is subjected to excessive force in the radial center direction by the shrinking housing 40 (protrusion 41f), as shown by the arrows in Fig. 4. In contrast, in this embodiment, as shown in Fig. 5, when the recess 41n formed in the protrusion 41f shrinks, the shrinkage force is dispersed not only in the radial center direction but also in the circumferential direction, thereby mitigating damage to the stator 3. Furthermore, the horizontal contraction force acts to sandwich the protrusion 3n provided on the stator 3, facilitating fixation of the housing 40 and the stator 3.

[0025] The recess 41n provided in the protruding portion 41f of the housing 40 and the protruding portion 3n provided in the stator 3 may have any shape as long as the recess 41n can sandwich the protruding portion 3n when it contracts. In other words, the recess 41n and the protruding portion 3n may not be completely fitted together. As long as the recess 41n expanded by heat is in contact with the protruding portion 3n at at least two points and can sandwich the protruding portion 3n, this falls within the technical scope of the present invention.

[0026] However, a larger contact area between the recess 41n and the protrusion 3n is more preferable because the force with which the recess 41n holds the protrusion 3n increases and the heat dissipation effect of the stator during motor operation is improved. Therefore, it is preferable that the recess 41n and the protrusion 3n have corresponding shapes. In this specification, the "corresponding shape of the recess 41n and the protrusion 3n" refers to a shape in which, when the recess 41n holds the protrusion 3n by shrink fitting, the recess 41n and the protrusion 3n have the same shape and size, and the contact surface between them is maximized.

[0027] The recesses 41n and the protrusions 3n may have any shape. However, as shown in FIG. 6, a tapered cross-section, such as a triangle (see FIG. 6A) or a trapezoid (see FIG. 6B), in a vertical cross section in the axial direction of the rotor 2 is preferable from the viewpoint of improving assembly, as it facilitates connection between the recesses 41n and the protrusions 3n and corrects misalignment. If the cross section is rectangular, it is preferable to form a taper near the entrance of the recess 41n (the portion where the inner circumferential surface of the recess intersects with the protruding end surface 41f1) or at the tip of the protrusion 3n (the portion where the flat portion at the tip of the protrusion intersects with the outer circumferential surface of the protrusion). Note that a tapered shape refers to a shape in which the width of the recess narrows radially outward. Therefore, the recesses 41n and the protrusions 3n may have a substantially semicircular cross-section.

[0028] The shape of the recesses 41n and the protrusions 3n when viewed three-dimensionally may be a groove or mountain range that is continuous in two dimensions (see Figure 7(A)), or may be a hole or mountain that does not have two-dimensional continuity (see Figure 7(B)).

[0029] Furthermore, although a certain degree of effect can be achieved regardless of the direction in which the groove structure formed in the housing 40 extends, extending the groove structure in the same direction as the longitudinal axis of the rotor 2 can particularly enhance the effect of suppressing freewheeling during rotation of the rotor 2. Furthermore, the longer the groove structure where the housing 40 and the stator 3 engage, the better. Furthermore, one protrusion 41f may have multiple groove structures.

[0030] The hole-like structure formed in the housing may be, for example, a cone, a polygonal pyramid (triangular pyramid, square pyramid, etc.), a truncated cone, a truncated pyramid (triangular pyramid, square pyramid, etc.), etc. In particular, a regular cone (regular cone, regular pyramid) and a regular truncated pyramid (regular circular cone, regular pyramid) are preferable in terms of stress distribution.

[0031] The recesses 41n and the protrusions 3n may be hemispherical, cylindrical, or prismatic. However, in the case of a cylindrical or prismatic shape, it is preferable to form the vicinity of the entrance of the recess 41n (the annular portion where the inner peripheral surface of the recess intersects with the protruding end surface 41f1) and the tip of the protrusion 3n (the annular portion where the flat portion at the tip of the protrusion intersects with the outer peripheral surface of the protrusion) in a tapered shape.

[0032] It is also preferable that there are multiple hole structures. When there are multiple hole structures, it is effective to arrange the positions of the hole structures at equal intervals in order to evenly distribute stress. Furthermore, when there are multiple hole structures, they may be composed of hole structures of different shapes (sizes, shapes), or may be combined with groove structures.

[0033] In either case, it is preferable that the convex structure is formed in a shape corresponding to the concave structure.

[0034] As described above, the motor for an electric compressor according to the present invention has recesses on the inner walls of the protrusions that protrude radially inward from the housing, and has protrusions on the outer peripheral surface of the stator that correspond to the recesses. This reduces the radially inward contraction force during shrink fitting, making it possible to prevent deformation of the stator, etc. Furthermore, it is possible to reduce deterioration of the magnetic properties of the stator core due to excessive stress.

[0035] Furthermore, it is preferable that the recessed and protruding portions have shapes that correspond to each other, since this increases the contact area between the stator and the housing, thereby improving the heat dissipation effect of the stator.

[0036] Furthermore, by making the recessed and protruding portions tapered, the recessed and protruding portions can be easily joined together and misalignment can be corrected.

[0037] The recesses may be groove-shaped, hole-shaped, or a combination of both.

[0038] 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.

[0039] 1: electric compressor, 2: rotor, 2a: rotating shaft, 3: stator, 3a: back yoke, 3b: teeth, 3c: slot, 3n: convex portion, 4: bobbin, 5: coil, 10: motor for electric compressor, 20: compression mechanism, 21: fixed scroll, 22: movable scroll, 30: inverter, 40: housing, 41: first housing, 41a: peripheral wall portion, 41b: partition wall portion, 41b1: support portion, 41c: fastening portion, 41f: protruding portion, 41f1: protruding end surface, 41n: concave portion, 42: second housing, 42a: cylindrical portion, 42b: bottom wall portion, 43: inverter cover, 44: compression mechanism cover, 45: bearing

Claims

1. An electric compressor motor having a stator and a rotor housed within a housing, wherein the housing has a recess on the inner wall of a protrusion that protrudes radially inward, and the stator has a protrusion on its outer surface that corresponds to the recess, and the protrusion is fixed in the recess by shrink fitting.

2. The motor for an electric compressor according to claim 1, wherein the recessed portion and the protruding portion have shapes corresponding to each other.

3. The motor for an electric compressor according to claim 1 or 2, wherein the recessed portion and the protruding portion are tapered.

4. The motor for an electric compressor according to claim 1 or 2, wherein the recessed portion is in the form of a groove and / or a hole.

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