motor

Abstract

This invention provides a motor that reduces iron loss in the stator during the fixing of the case to the stator, thereby achieving excellent efficiency. [Solution] The motor 1 comprises a cylindrical case 2 and a stator core 31 formed by stacking a plurality of annular-shaped electromagnetic steel sheets 41, each of which is arranged inside the case 2. The case 2 has a helical groove 11 on its inner circumferential surface 2c. The plurality of electromagnetic steel sheets 41 include a plurality of first electromagnetic steel sheets 42 arranged in a continuous manner, each having a projection 51 that protrudes radially outward from the stator core 31. The stator core 31 has a helical step-shaped outer peripheral projection 45 formed by sequentially shifting the positions of the projections 51 of each of the plurality of first electromagnetic steel sheets 42 by at least one in the circumferential direction of the stator core 31. The case 2 and the stator core 31 are fixed to each other by the outer peripheral projection 45 of the stator core 31 fitting into the helical groove 11 of the case 2.

Description

Technical Field

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[0001] Embodiments of the present invention relate to a motor.

Background Art

[0002] There is known a motor that aims to ensure efficiency by reducing iron loss generated in a stator when the stator is press-fitted and fixed to a motor case. The motor has an engagement structure that regulates relative rotation of the stator with respect to the motor case by engaging a part of each other between an outer peripheral surface of the stator and an inner peripheral surface of the motor case. The engagement structure reduces the press-fitting allowance, which is the dimensional difference between the outer diameter of the stator and the inner diameter of the motor case, and reduces the compressive stress generated in the stator when the stator is press-fitted and fixed to the motor case. Thereby, the iron loss in the stator caused by the compressive stress is reduced.

Prior Art Documents

Patent Documents

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[0006] To solve the aforementioned problems, a motor according to an embodiment of the present invention comprises a cylindrical case and a stator core formed by laminating a plurality of annular-shaped electromagnetic steel sheets, each of which is disposed inside the case, wherein the case has a helical groove on its inner circumferential surface, the plurality of electromagnetic steel sheets include a plurality of first electromagnetic steel sheets arranged in a continuous manner and each having a projection that protrudes radially outward from the stator core, the stator core has a helical step-shaped outer projection formed by sequentially shifting the positions of the projections of each of the plurality of first electromagnetic steel sheets by at least one in the circumferential direction of the stator core, and the case and the stator core are fixed to each other by the outer projection of the stator core fitting into the helical groove of the case.

[0007] To solve the aforementioned problems, a motor according to an embodiment of the present invention comprises a cylindrical case and a stator core formed by laminating a plurality of annular electromagnetic steel sheets, each having an annular shape, and disposed inside the case, wherein the case has a spiral-shaped inner projection on its inner surface, the plurality of electromagnetic steel sheets include a plurality of first electromagnetic steel sheets arranged in a continuous manner and each having a recess recessed radially inward of the stator core, the stator core has a spiral staircase-shaped outer groove formed by sequentially shifting the position of each of the plurality of first electromagnetic steel sheets' recesses by at least one in the circumferential direction of the stator core, and the case and the stator core are fixed to each other by the outer groove of the stator core fitting into the inner projection of the case. [Effects of the Invention]

[0008] The present invention provides a motor that reduces iron loss in the stator when the case and stator are fixed together, thereby achieving excellent efficiency. [Brief explanation of the drawing]

[0009] [Figure 1] A perspective view showing a motor according to an embodiment of the present invention. [Figure 2]A perspective view showing a part of the inside of a motor according to an embodiment of the present invention. [Figure 3] A perspective view showing the motor case and stator core according to an embodiment of the present invention. [Figure 4] A plan view showing the motor case and stator core according to an embodiment of the present invention. [Figure 5] A perspective view showing a motor case according to an embodiment of the present invention. [Figure 6] A side view showing the stator core of a motor according to an embodiment of the present invention. [Figure 7] (A) A plan view showing two first electromagnetic steel sheets of a motor according to an embodiment of the present invention stacked together; (B) A plan view showing the upper first electromagnetic steel sheet in Figure 7(A); (C) A plan view showing the lower first electromagnetic steel sheet in Figure 7(A). [Figure 8] A perspective view showing the situation in which the stator core is fitted into the case in a motor according to an embodiment of the present invention. [Figure 9] Cross-sectional view AA in Figure 4. [Figure 10] Enlarged view of the region S enclosed by the dashed line in Figure 9. [Figure 11] A side view showing another example of a stator core of a motor according to an embodiment of the present invention. [Figure 12] A plan view showing a second electromagnetic steel sheet of a motor according to an embodiment of the present invention. [Figure 13] (A) A plan view showing another example of the first electromagnetic steel sheet of a motor according to an embodiment of the present invention, and (B) A plan view showing two of the first electromagnetic steel sheets of Figure 13(A) stacked together. [Figure 14] This is a cross-sectional view in which the cross-sectional view AA in Figure 4 is replaced with the case and stator core of a second example motor according to an embodiment of the present invention. [Figure 15] Enlarged view of region S' enclosed by the dashed line in Figure 14. [Figure 16](A) Plan view showing a state where two first electromagnetic steel sheets of a second example of a motor according to an embodiment of the present invention are laminated, (B) Plan view showing the upper-first electromagnetic steel sheet in Fig. 16(A), (C) Plan view showing the lower-first electromagnetic steel sheet in Fig. 16(A).

Embodiments for Carrying out the Invention

[0010] Embodiments of the motor according to the present invention will be described with reference to Figs. 1 and 16. In the plurality of drawings, the same or corresponding components are denoted by the same reference numerals.

[0011] Fig. 1 is a perspective view showing a motor according to an embodiment of the present invention.

[0012] Fig. 2 is a perspective view showing a part inside the motor according to an embodiment of the present invention.

[0013] The motor 1 shown in Fig. 1 is a motor for generating a driving force for a vehicle. The motor 1 is, for example, an embedded magnet type permanent magnet synchronous motor. As shown in Figs. 1 and 2, the motor 1 includes a case 2, two covers 3, a rotating shaft 5, a rotor 7, and a stator 10. The rotating shaft 5, the rotor 7, and the stator 10 are housed in the case 2. The center line P of the case 2 and the stator 10 substantially coincides with the rotation center line C of the rotating shaft 5 and the rotor 7.

[0014] The case 2 has a cylindrical shape extending in the direction along the center line P. The case 2 is a metal member. The case 2 has openings 2a at both ends. The opening 2a is also a part of a through hole that penetrates the case 2 in the direction along the center line P.

[0015] The two covers 3 respectively cover the openings 2a at both ends of the case 2. The cover 3 is a metal member. The cover 3 has a through hole 3a through which the rotating shaft 5 passes.

[0016] The rotating shaft 5 is fixed so as to be circumferentially rotatable via bearings (not shown) provided in each of the two covers 3.

[0017] The rotor 7 is fixed to the rotating shaft 5 and is located inside the stator 10. In other words, the rotor 7 is located inside the stator 10 and is supported so as to be rotatable in the circumferential direction. The rotor 7 also includes a rotor core 21 made of multiple electromagnetic steel sheets (not shown) stacked in a direction along the rotational centerline C, multiple permanent magnets 23 arranged inside the rotor core 21, and end plates (not shown) arranged at both ends of the rotor core 21. The end plates prevent the multiple permanent magnets 23 arranged inside the rotor core 21 from falling out.

[0018] The rotor core 21 has multiple magnet insertion holes 21a and a central hole 21b in which the rotating shaft 5 is positioned, as holes that penetrate in a direction along the rotation centerline C. In the rotor core 21, both the magnet insertion holes 21a and the central hole 21b extend parallel to the rotation centerline C.

[0019] Each of the multiple magnet insertion holes 21a is a hole in which at least one permanent magnet 23 is placed.

[0020] The central hole 21b is where the rotating shaft 5 is positioned and is a hole for fixing the rotor core 21, and consequently the rotor 7, to the rotating shaft 5. The rotor core 21 is fixed to the rotating shaft 5 by, for example, press-fitting or shrink-fitting.

[0021] The stator 10 has a generally cylindrical shape that extends in a direction along the center line P. The stator 10 is positioned inside the case 2 and fixed to the case 2. The stator 10 has a stator core 31 and a coil 33 wound around the stator core 31. The stator 10 generates a rotating magnetic field when current flows through the coil 33. The stator 10 also generates heat when it generates a rotating magnetic field. In other words, when the motor 1 is in operation, the stator 10 generates heat.

[0022] Figure 3 is a perspective view showing the case and stator core of a motor according to an embodiment of the present invention.

[0023] Figure 4 is a plan view showing the case and stator core of a motor according to an embodiment of the present invention.

[0024] As shown in Figures 1 and 2, as well as Figures 3 and 4, the stator core 31 has a cylindrical shape extending in a direction along the center line P. The stator core 31 is located inside the case 2 and fixed to the case 2. In other words, the stator 10 is fixed to the case 2 via the stator core 31. The stator core 31 also has a plurality of teeth portions 31a that protrude from its inner circumferential surface and are spaced apart and arranged in the circumferential direction, and slot portions 31b between two adjacent teeth portions 31a. The plurality of teeth portions 31a face each other at a certain distance from the outer circumferential surface of the rotor 7. Coils 33 are wound around the plurality of teeth portions 31a. The slot portions 31b are spaces in which the coils 33 wound around the teeth portions 31a are arranged.

[0025] Furthermore, the stator core 31 has an end face 31c that lies on the same plane as the end face 2b of the case 2. The same plane is a plane perpendicular to the direction along the center line P. In addition, the stator core 31 has a through hole 31d. The diameter of the through hole 31d is larger than the diameter of the rotor 7. The through hole 31d is a hole for arranging the rotor 7.

[0026] Furthermore, the stator core 31 is a laminate formed by stacking multiple electromagnetic steel sheets 41, each having an annular shape, in a direction along the center line P. That is, the teeth portion 31a, the slot portion 31b, and the through hole 31d are provided in each of the multiple electromagnetic steel sheets 41 in the stator core 31. In the stator core 31, the teeth portion 31a, the slot portion 31b, and the through hole 31d all extend parallel to the center line P. The thickness direction of the electromagnetic steel sheets 41 substantially coincides with the direction along the center line P. In other words, the stator core 31 is a laminate formed by stacking multiple electromagnetic steel sheets 41 in the thickness direction of the electromagnetic steel sheets 41.

[0027] Figure 5 is a perspective view showing the case of a motor according to an embodiment of the present invention.

[0028] Figure 6 is a side view showing the stator core of a motor according to an embodiment of the present invention.

[0029] Figure 7(A) is a plan view showing two first electromagnetic steel sheets of a motor according to an embodiment of the present invention stacked together. Figure 7(B) is a plan view showing the upper first electromagnetic steel sheet in Figure 7(A). Figure 7(C) is a plan view showing the lower first electromagnetic steel sheet in Figure 7(A).

[0030] Figure 8 is a perspective view showing the process of fitting the stator core into the case in a motor according to an embodiment of the present invention.

[0031] Incidentally, as mentioned above, in conventional motors, the stator is fixed to the case by press-fitting, which tends to increase iron loss. Therefore, there is a risk of increased iron loss in the stator. Also, if the case and stator are fixed by shrink-fitting instead of press-fitting, there is a risk of increased iron loss.

[0032] Therefore, as shown in Figures 5 to 8, the motor 1 in this embodiment comprises a case 2 having the following features and a stator core 31.

[0033] Specifically, as shown in Figure 5, the case 2 has a spiral groove 11, which is a spiral-shaped groove provided on the inner circumferential surface 2c of the case 2. The spiral groove 11 is provided on the inner circumferential surface 2c from one end face 2b to the other end face 2b of the case 2. Furthermore, as shown in Figures 6 and 7(A) to 7(C), the stator core 31 has a plurality of electromagnetic steel sheets 41, including a plurality of first electromagnetic steel sheets 42 which are arranged continuously on the stator core 31 and each has a projection 51 that protrudes radially outward from the outer circumferential edge of the stator core 31. In addition, the stator core 31 has spiral staircase-shaped outer projections 45 formed by sequentially shifting the positions of each projection 51 of the plurality of first electromagnetic steel sheets 42 by at least one in the circumferential direction of the stator core 31. The case 2 and the stator core 31 are fixed to each other by the outer projections 45 fitting into the spiral groove 11. In other words, the helical groove 11 of case 2 becomes a female thread, and the outer peripheral projection 45 of the stator core 31 becomes a male thread. Then, as shown in Figure 8, for example, the outer peripheral projection 45, which is a male thread, is fitted into the helical groove 11, which is a female thread, while rotating it in the rotational direction R. This fitting of the helical groove 11 and the outer peripheral projection 45 to fix case 2 and stator core 31, that is, to fix case 2 and stator 10, reduces the compressive stress applied from case 2 to stator core 31 compared to fixing by press-fitting and shrink-fitting, and can significantly reduce the occurrence of iron loss in stator core 31 caused by compressive stress.

[0034] The helical groove 11 has an introduction portion 11a on the end face 2b of the case 2 for guiding the outer peripheral projection 45. Furthermore, the fixing of the case 2 and the stator core 31 by the fitting of the helical groove 11 and the outer peripheral projection 45, that is, the fixing of the case 2 and the stator 10, may hereafter be referred to as screw fitting.

[0035] Figure 9 is a cross-sectional view of AA in Figure 4. For the sake of clarity, the teeth portion 31a and the slot portion 31b are omitted from the illustration in Figure 9.

[0036] Figure 10 is an enlarged view of the region S enclosed by the dashed line in Figure 9.

[0037] Furthermore, as shown in Figures 9 and 10, a gap 61 may be provided between the helical groove 11 of the case 2 and the outer peripheral projection 45 of the stator core 31 in the direction along the center line P, that is, in the stacking direction of the multiple electromagnetic steel sheets 41 (stator core 31 stacking direction), through which a coolant for cooling the stator core 31 can flow. By doing so, the coolant can be circulated through the gap 61 to cool the stator core 31, that is, the stator 10, which generates heat when the motor 1 is in operation.

[0038] The size of the gap 61 can be easily adjusted, for example, by changing the width of the spiral groove 11. The motor 1 also typically includes a refrigerant flow path (not shown) located in the case 2. This refrigerant flow path circulates the refrigerant to suppress heat generation throughout the motor 1. The refrigerant circulated in the gap 61 can be the same refrigerant flowing through the refrigerant flow path in the case 2.

[0039] Figure 11 is a side view showing another example of a stator core of a motor according to an embodiment of the present invention.

[0040] Figure 12 is a plan view showing the second electromagnetic steel sheet of a motor according to an embodiment of the present invention.

[0041] Furthermore, as shown in Figures 11 and 12, the multiple electromagnetic steel sheets 41 may include at least one second electromagnetic steel sheet 43 that is positioned in locations other than where the multiple first electromagnetic steel sheets 42 are located on the stator core 31 and does not have protrusions 51, as long as the fit strength (fixing strength) between the case 2 and the stator 10 by screw fitting is not impaired. In this way, the stator core 31 will have locations where the spiral staircase-shaped outer peripheral protrusions 45 are discontinuous, that is, missing locations where the outer peripheral protrusions 45 do not exist. As a result, the gap 61 between the spiral groove 11 of the case 2 and the outer peripheral protrusions 45 of the stator core 31 is enlarged in the missing locations of the outer peripheral protrusions 45. Therefore, when the gap 61 is used as a flow path for the refrigerant, the flow resistance that obstructs the flow of the refrigerant is reduced, making it easier for the refrigerant to flow. Thus, the cooling efficiency of the stator 10 is further improved while maintaining the fit between the case 2 and the stator core 31.

[0042] In the example shown in Figure 11, there is a missing portion of the outer peripheral projection 45 near the center of the stator core 31 in the stacking direction. However, the example is not limited to this location; for example, the missing portion of the outer peripheral projection 45 may be located near at least one end face 31c of the stator core 31.

[0043] Furthermore, it is preferable that the stator core 31 has a spiral staircase-shaped outer peripheral projection 45 formed by sequentially shifting the positions of the projections 51 of each of the multiple first electromagnetic steel sheets 42 by at least two positions in the circumferential direction of the stator core 31. In other words, it is preferable that the projections 51 of at least two of the first electromagnetic steel sheets 42 are aligned and overlapping without misalignment. The thickness of the electromagnetic steel sheets 41 is usually thin in order to reduce iron loss. Therefore, there is a risk that the strength of the spiral staircase-shaped outer peripheral projection 45 will be reduced. By forming a spiral staircase-shaped outer peripheral projection 45 by sequentially shifting the positions of the projections 51 of each of the multiple first electromagnetic steel sheets 42 by at least two positions, the reduction in strength of the outer peripheral projection 45 is suppressed. In other words, screw fitting can be stably achieved without damage to the outer peripheral projection 45.

[0044] Figure 13(A) is a plan view showing another example of the first electromagnetic steel sheet of a motor according to an embodiment of the present invention, and Figure 13(B) is a plan view showing two of the first electromagnetic steel sheets of Figure 13(A) stacked together.

[0045] Furthermore, depending on the specifications such as the size and pitch of the female screw thread (helical groove 11) and the male screw thread (outer circumference projection 45), the multiple first electrical steel sheets 42A may each have the same outer shape, as shown in Figures 13(A) and 13(B).

[0046] Specifically, as shown by returning from Figure 7(A) to Figure 7(C), among the multiple first electromagnetic steel sheets 42 that constitute the outer peripheral projection 45 of the stator core 31, two overlapping first electromagnetic steel sheets 42 may have different positions on which the projection 51 is provided. In this case, it is necessary to prepare first electromagnetic steel sheets 42 with different external shapes. On the other hand, if multiple first electromagnetic steel sheets 42A each have the same external shape, it is not necessary to prepare first electromagnetic steel sheets 42 with different external shapes, thus improving manufacturability.

[0047] Next, assuming that the motor 1 described so far according to this embodiment is the motor 1 of the first example, another example of the motor 1 of the first example (the second example) will be described. In the motor 1A described in the second example, the same reference numerals are used for components that are the same as those in the motor 1 of the first example, and redundant explanations are omitted.

[0048] Figure 14 is a cross-sectional view obtained by replacing the cross-sectional view AA of Figure 4 with the case and stator core of a second example motor according to an embodiment of the present invention.

[0049] Figure 15 is an enlarged view of the region S' enclosed by the dashed line in Figure 14.

[0050] Figure 16(A) is a plan view showing two first electromagnetic steel sheets of a motor according to a second embodiment of the present invention stacked together; Figure 16(B) is a plan view showing the upper first electromagnetic steel sheet in Figure 16(A); and Figure 16(C) is a plan view showing the lower first electromagnetic steel sheet in Figure 16(A).

[0051] As shown in Figures 14 to 16 in addition to Figure 1, the second example motor 1A according to this embodiment (hereinafter sometimes simply referred to as "motor 1A") differs from the first example motor 1 in that motor 1A has a case 2A and a stator core 31A that are different from the case 2 and stator core 31 of the first example motor 1.

[0052] Specifically, as shown in Figures 14 and 15, the case 2A of the motor 1A has an inner circumferential projection 12, which is a helical projection provided on the inner circumferential surface 2Ac of the case 2A. In other words, while the case 2 has a helical groove 11, the case 2A has a helical inner circumferential projection 12. In addition to Figures 14 and 15, as shown in Figures 16(A) to 16(C), the stator core 31A has a plurality of electromagnetic steel sheets 41, including a plurality of first electromagnetic steel sheets 42B that are arranged continuously on the stator core 31A and each has a recess 52 that is recessed radially inward from the outer circumferential edge of the stator core 31A. Furthermore, the stator core 31A has a helical step-shaped outer circumferential groove 46 formed by sequentially shifting the positions of each recess 52 of the plurality of first electromagnetic steel sheets 42B by at least one in the circumferential direction of the stator core 31A. In other words, while the stator core 31A has a spiral staircase-shaped outer groove 46, the stator core 31 has a spiral staircase-shaped outer groove 46. The case 2A and the stator core 31A are fixed to each other by the outer groove 46 fitting into the inner groove 12. That is, the inner groove 12 of the case 2A becomes a male thread, and the outer groove 46 of the stator core 31A becomes a female thread. With this method of fixing the case 2A and the stator core 31A by fitting the inner groove 12 and the outer groove 46, the compressive stress applied from the case 2A to the stator core 31A can be reduced compared to fixing by press-fitting or shrink-fitting, and the occurrence of iron loss due to compressive stress can be greatly reduced.

[0053] As shown in Figures 14 and 15, a gap 62 may be provided between the inner circumferential projection 12 of the case 2A and the outer circumferential groove 46 of the stator core 31A in the direction along the center line P, that is, in the stacking direction of the multiple electromagnetic steel sheets 41 (stator core 31A stacking direction), through which a coolant for cooling the stator core 31A can flow. By doing so, the coolant can be circulated through the gap 62 to cool the stator core 31A, which generates heat when the motor 1A is in operation.

[0054] As described above, the motor 1 according to this embodiment comprises a case 2 having a helical groove 11 on its inner circumferential surface 2c, and a stator core 31 formed by laminating a plurality of electromagnetic steel sheets 41, including a plurality of first electromagnetic steel sheets 42 that are arranged in a continuous manner and each has a projection 51 that protrudes radially outward from the stator core 31. The stator core 31 has a helical step-shaped outer peripheral projection 45 formed by sequentially shifting the positions of the projections 51 of each of the plurality of first electromagnetic steel sheets 42 by at least one in the circumferential direction of the stator core 31. The case 2 and the stator core 31 are fixed to each other by the outer peripheral projection 45 of the stator core 31 fitting into the helical groove 11 of the case 2. With this type of fitting between the helical groove 11 and the outer peripheral projection 45, that is, fixing by screw fitting, the compressive stress applied from the case 2 to the stator core 31 can be reduced compared to fixing by press fitting and shrink fitting. In other words, the occurrence of iron loss in the stator core 31 due to increased compressive stress can be significantly reduced. Therefore, when fixing the case 2 to the stator 10, the motor 1 reduces the iron loss that occurs in the stator core 31 and, consequently, in the stator 10, thereby achieving excellent efficiency.

[0055] Furthermore, press-fitting and shrink-fitting methods require complex equipment and manufacturing processes. On the other hand, screw-fitting allows the case 2 and stator core 31 to be fixed using relatively simple equipment and manufacturing processes. Therefore, the motor 1 can improve both manufacturing cost and manufacturing efficiency.

[0056] Furthermore, in the motor 1 according to this embodiment, a gap 61 is provided between the helical groove 11 of the case 2 and the outer peripheral projection 45 of the stator core 31 in the stacking direction of the multiple electromagnetic steel sheets 41, through which a coolant for cooling the stator core 31 can flow. Therefore, the motor 1 can circulate the coolant through the gap 61 to cool the stator core 31 and, consequently, the stator 10, which generates heat when the motor 1 is in operation. Thus, the motor 1 can suppress the decrease in motor efficiency caused by heat generation.

[0057] Furthermore, the motor 1 according to this embodiment includes a plurality of electromagnetic steel sheets 41, including at least one second electromagnetic steel sheet 43 that is arranged in locations other than where a plurality of first electromagnetic steel sheets 42 are arranged and does not have protrusions 51. In the locations on the outer circumferential surface of the stator core 31 where the second electromagnetic steel sheets 43 are laminated, there are no protrusions 51, and therefore these become missing locations where the outer circumferential protrusions 45 do not exist. In the missing locations of the outer circumferential protrusions 45, the gap 61 between the helical groove 11 of the case 2 and the outer circumferential protrusions 45 of the stator core 31 is enlarged. Therefore, when the gap 61 is used as a flow path for refrigerant, the flow resistance that obstructs the flow of refrigerant is reduced, making it easier for the refrigerant to flow. In other words, the amount of refrigerant flowing through the gap 61 per unit time increases. Thus, the motor 1 can further improve the cooling efficiency of the stator core 31 and, consequently, the stator 10, while maintaining the fit between the case 2 and the stator core 31.

[0058] Furthermore, the motor 1 according to this embodiment includes a stator core 31 having spiral staircase-shaped outer peripheral protrusions 45 formed by sequentially shifting the positions of each of the protrusions 51 of a plurality of first electromagnetic steel sheets 42 by at least two in the circumferential direction of the stator core 31. Therefore, the motor 1 can suppress a decrease in the strength of the outer peripheral protrusions 45 and stably achieve a fit between the case 2 and the stator core 31 without damaging the outer peripheral protrusions 45.

[0059] Furthermore, the motor 1 according to this embodiment includes a plurality of first electromagnetic steel sheets 42A having the same external shape. Therefore, the motor 1 can improve manufacturability compared to the case where first electromagnetic steel sheets 42 with different external shapes are prepared separately.

[0060] Furthermore, the second example motor 1A according to this embodiment includes a case 2A having an inner circumferential projection 12 which is a helical projection, instead of the case 2 of the first example motor 1, and a stator core 31A having a helical stepped outer groove 46 instead of the stator core 31 of the first example motor 1. By fixing the case 2A and the stator core 31A by fitting the inner circumferential projection 12 and the outer groove 46, the compressive stress applied from the case 2A to the stator core 31A can be reduced compared to fixing by press-fitting and shrink-fitting, and the occurrence of iron loss due to compressive stress can be greatly reduced. Therefore, the second example motor 1A has the same effect as the first example motor 1.

[0061] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0062] 1, 1A...Motor, 2, 2A...Case, 2a...Opening, 2b...End face, 2c, 2Ac...Inner circumferential surface, 3...Cover, 3a...Through hole, 5...Rotating shaft, 7...Rotor, 10...Stator, 11...Spiral groove, 11a...Inlet, 12...Inner circumferential projection, 21...Rotor core, 21a...Magnet insertion hole, 21b...Center hole, 23...Permanent magnet, 31, 31A...Stator core, 31a...Teeth part, 31b...Slot part, 31c...End face, 31d...Through hole, 33...Coil, 41...Electromagnetic steel sheet, 42, 42A, 42B...First electromagnetic steel sheet, 43...Second electromagnetic steel sheet, 45...Outer circumferential projection, 46...Outer circumferential groove, 51...Protrusion, 52...Recess, 61, 62...Gap.

Claims

1. A case having a cylindrical shape, It comprises a stator core, which is formed by laminating multiple electromagnetic steel sheets, each having an annular shape, and is positioned inside the case, The case has a helical groove on its inner circumferential surface, The plurality of electromagnetic steel sheets include a plurality of first electromagnetic steel sheets arranged in a continuous manner, each having a projection that protrudes radially outward from the stator core. The stator core has a spiral staircase-shaped outer projection formed by sequentially shifting the positions of the projections of each of the plurality of first electromagnetic steel sheets by at least one in the circumferential direction of the stator core, A motor in which the case and the stator core are fixed to each other by the outer peripheral projection of the stator core fitting into the helical groove of the case.

2. The motor according to claim 1, wherein, in the lamination direction of the plurality of electromagnetic steel sheets, a gap is provided between the helical groove of the case and the outer peripheral projection of the stator core, through which a coolant for cooling the stator core can flow.

3. The motor according to claim 2, wherein the plurality of electromagnetic steel sheets include at least one second electromagnetic steel sheet that is arranged in a location on the stator core other than the location where the plurality of first electromagnetic steel sheets are arranged and does not have the protrusions.

4. The motor according to claim 1, wherein the stator core has spiral staircase-shaped outer peripheral protrusions formed by sequentially shifting the positions of the protrusions of each of the plurality of first electromagnetic steel sheets by at least two in the circumferential direction of the stator core.

5. The motor according to any one of claims 1 to 4, wherein each of the plurality of first electromagnetic steel sheets has the same external shape.

6. A case having a cylindrical shape, It comprises a stator core, which is formed by laminating multiple electromagnetic steel sheets, each having an annular shape, and is positioned inside the case, The case has a spiral-shaped inner circumferential projection on its inner surface. The plurality of electromagnetic steel sheets include a plurality of first electromagnetic steel sheets arranged in a continuous manner, each having a recess that is recessed radially inward of the stator core. The stator core has a spiral staircase-shaped outer groove formed by sequentially shifting the position of each of the recesses of the plurality of first electromagnetic steel sheets by at least one in the circumferential direction of the stator core, A motor in which the case and the stator core are fixed to each other by the outer circumferential groove of the stator core fitting into the inner circumferential projection of the case.

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