Permanent magnet embedded motor and pump device

Abstract

The invention provides a permanent magnet embedded type motor and a pump device using the permanent magnet embedded type motor as a driving source, which can inhibit or prevent generation of local stress and obtain a firm structure without increasing processing cost, complicating and enlarging the structure of a housing, and the like, and a pump device using the permanent magnet embedded type motor as a driving source. The permanent magnet embedded motor includes: a stator (St) including a stator core (20) formed in an annular shape by laminating a plurality of steel plates (Sp) obtained by press working by rolling a steel plate material, and an excitation coil (40); a rotor (Rt) disposed on the inner side of the stator and including a permanent magnet (60); and a metal housing (1) which includes a cylindrical fitting recess (1b) centered on a predetermined axis (S) and into which the stator (St) is fitted, the stator (St) being heat-fitted to the housing in such a manner that the rolling direction (Rd) of the steel plate is oriented in an expansion direction (Ed) in which the amount of change in the inner diameter (D) of the fitting recess (1b) is large when the housing is heated.

Description

Technical Field

[0001] The present invention relates to a permanent magnet embedded type motor including a stator on which a coil is wound and a rotor in which a permanent magnet is embedded, and a pump device using the motor as a driving source. Background Art

[0002] As an existing permanent magnet embedded motor, the following permanent magnet motor is known: it includes a stator, which includes an annular stator core having teeth and slots arranged in a circumferential direction and a coil wound around the teeth; a rotor, which is rotatably arranged on the inner side of the stator and for inserting permanent magnets; and a casing, which fixes the stator core and supports the rotor so that it can rotate freely (for example, patent document 1).

[0003] In the permanent magnet type motor, the stator core is formed by laminating a plurality of electromagnetic steel sheets punched from thin electromagnetic steel sheets in order to reduce iron loss caused by eddy current loss, and is fixed in a housing by shrink fitting or the like.

[0004] However, the electromagnetic steel sheet is provided as a coil obtained by rolling the manufactured steel sheet (steel block) in a predetermined direction, and appropriately performing heat treatment, etc., to form a strip steel sheet, and then winding the strip steel sheet. Furthermore, when forming a plurality of electromagnetic steel sheets that become the base material of the stator core, the coil is stretched into a flat plate, and a press process is performed while sequentially feeding to manufacture an electromagnetic steel sheet of a designed size.

[0005] However, due to residual strain caused by rolling of electromagnetic steel sheets, processing errors when the coiled material of the electromagnetic steel sheets is stretched and then pressed, if a plurality of stamped electromagnetic steel sheets are stacked to form a stator core, there is a tendency that the stress in the rolling direction is slightly larger than the design value. If the processing accuracy is improved to cope with this, the processing cost will increase.

[0006] Furthermore, when the housing is heated and expanded and the stator core is fixed by shrink fitting, the housing has a non-fixed thermal expansion coefficient depending on its shape and method, and after shrink fitting, there is a possibility that areas with locally increased internal stress will be generated in the housing or stator core.

[0007] Therefore, taking into account the dimensional tolerance and geometric tolerance of the stator core and the housing, as well as the rolling process of the electromagnetic steel sheet and the dimensional error depending on the coil, it is hoped to suppress or prevent local stress generated in each part, and to form a more reliable structure.

[0008] [Prior art literature]

[0009] [Patent Document]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 2022-116563 Summary of the invention

[0011] [Problems to be solved by the invention]

[0012] The present invention has been completed in view of the above situation, and its purpose is to provide a permanent magnet embedded motor and a pump device using it as a driving source in view of the problems of the above-mentioned prior art, which does not lead to an increase in processing costs, complexity and enlargement of the casing structure, etc., and can suppress or prevent the generation of local stress, thereby obtaining a strong structure.

[0013] [Technical means to solve the problem]

[0014] The permanent magnet embedded motor of the present invention includes: a stator, including a stator core and a coil for excitation formed into a circular ring shape by stacking multiple steel plates obtained by stamping rolled steel plates; a rotor, which is arranged on the inner side of the stator and includes permanent magnets; and a metal shell, including a cylindrical fitting recess centered on a specified axis to embed the stator, and the permanent magnet embedded motor is constructed as follows: the stator is hot-mounted on the shell by orienting the rolling direction of the steel plate to the expansion direction in which the inner diameter of the fitting recess changes greatly when the shell is heated.

[0015] In the permanent magnet embedded motor, the following structure can be adopted: the shell includes a wall portion and a thick wall portion, the wall portion defines a fitting recess, the thick wall portion is continuous with the wall portion around the opening side of the fitting recess and is formed to be thicker than the wall portion, and the expansion direction is consistent with the angular position around the axis where the cross-sectional area of ​​the thick wall portion becomes the largest in the cross-section including the axis.

[0016] In the permanent magnet embedded motor, the following structure can be adopted: the shell includes a wall portion and two thick-walled portions, the wall portion defines a fitting recess, the two thick-walled portions are continuously formed on the opening side of the fitting recess, around the wall portion and in the direction of an orthogonal line orthogonal to the axis and are thicker than the wall portion, and the stator is hot-mounted to the shell by orienting the rolling direction as the arrangement direction of the two thick-walled portions.

[0017] In the permanent magnet embedded motor, the following structure can be adopted: the shell includes: a wall portion, which defines a fitting recess; a flange portion, which is formed around the wall portion on the opening side of the fitting recess; and two boss portions, which are arranged in the flange portion along a direction of an orthogonal line perpendicular to the axis and are thicker than the wall portion. The stator is hot-mounted to the shell by orienting the rolling direction to the arrangement direction of the two boss portions.

[0018] In the permanent magnet embedded motor including the two boss portions, a structure may be adopted in which the flange portion is formed thicker than the wall portion.

[0019] In the permanent magnet embedded motor including the two boss portions, a structure may be adopted in which the two boss portions are formed thicker than the flange portion.

[0020] In the embedded permanent magnet motor including the two boss portions, a structure may be adopted in which the flange portion includes a plurality of thin-walled portions in a region deviating from a region through which the orthogonal line passes.

[0021] In the above-mentioned embedded permanent magnet motor, a structure may be adopted in which the stator includes an indicator indicating a rolling direction.

[0022] In the above-mentioned permanent magnet embedded motor, the following structure may be adopted: the plate thickness of the steel plate is 0.2 mm to 0.5 mm.

[0023] In the above-mentioned embedded permanent magnet motor, a structure may be adopted in which the housing is formed of an aluminum material.

[0024] In the above-mentioned embedded permanent magnet motor, a structure may be adopted in which the stator core has teeth and slots arranged in the circumferential direction, and the stator includes a coil wound around the teeth via a resin bobbin.

[0025] In the permanent magnet embedded motor, the following structure may be adopted: the rotor includes: a cylindrical rotor core formed by laminating a plurality of steel plates obtained by stamping rolled steel plates and having insertion holes arranged in the circumferential direction; and permanent magnets inserted in the insertion holes.

[0026] The pump device of the present invention includes: a pump unit for sucking and discharging fluid; a rotating shaft connected to the pump unit; and a driving source for applying driving force to the rotating shaft. The pump device is constructed as follows: as a driving source, a permanent magnet embedded motor constituting any one of the above structures is used.

[0027] In the pump device, a configuration may be adopted in which the pump unit is a trochoid pump including an inner rotor connected to the rotating shaft and an outer rotor meshing with the inner rotor.

[0028] [Effects of the Invention]

[0029] According to the permanent magnet embedded type motor constituting the above structure, the generation of local stress (stress concentration) can be suppressed or prevented without causing an increase in processing costs, complexity and enlargement of the structure of the housing, etc., thereby obtaining a strong structure. In addition, by using the permanent magnet embedded type motor constituting the above structure as a driving source, a pump device with high reliability can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a perspective view showing the appearance of a pump device including the internal permanent magnet motor of the present invention.

[0031] Figure 2 yes Figure 1 A cross-sectional view of the pump assembly is shown.

[0032] Figure 3 yes Figure 1 An exploded perspective view of the pump device is shown.

[0033] Figure 4 Yes means Figure 1 The diagram shows a suction port and a discharge port of a fluid in the pump device shown, and is a cross-sectional view on a plane perpendicular to the axis line, which is the rotation center line of the rotor.

[0034] Figure 5 It means composition Figure 1 The pump device shown is a plan view of a housing body which is a part of a housing.

[0035] Figure 6 yes Figure 5 The external perspective view of the shell body is shown.

[0036] Figure 7 is along Figure 6 A three-dimensional cross-sectional view of the shell body along line XX.

[0037] Figure 8 Yes means Figure 1 This is a perspective view of the appearance of a permanent magnet embedded type motor as a driving source included in the pump device shown.

[0038] Fig. 9 yes Figure 8 An exploded perspective view of the permanent magnet embedded motor shown.

[0039] Fig.10 Yes means Figure 8 The diagram shows the internal structure of the permanent magnet embedded motor, and is a cross-sectional view taken on a plane perpendicular to the axis.

[0040] Fig.11 It means composition Figure 8 The external perspective view of a part of the stator core of the permanent magnet embedded motor shown.

[0041] Fig.12 Observed from one end Fig.11 A plan view of the stator core is shown.

[0042] Fig.13 The diagram schematically shows a process of manufacturing a steel plate for forming a stator core from a rolled steel plate by press working.

[0043] Fig.14 The structure is viewed from one end. Figure 8 A perspective view of the appearance of a rotor that is a part of a permanent magnet embedded motor is shown.

[0044] Fig.15 The structure is viewed from the other side. Figure 8A perspective view of the appearance of a rotor that is a part of a permanent magnet embedded motor is shown.

[0045] Fig.16 This is a plan view of a rotor core constituting a part of the interior permanent magnet motor as viewed from one end side.

[0046] Fig.17 This is a process diagram showing a step of heating a case body constituting a part of the case and shrink-fitting the stator into a fitting recess of the case body.

[0047] Fig.18 This is a process diagram showing a step of heating a case body constituting a part of the case and shrink-fitting the stator into a fitting recess of the case body.

[0048] Fig.19 This is a process diagram showing a step of heating a case body constituting a part of the case and shrink-fitting the stator into a fitting recess of the case body.

[0049] Fig. 20 1 is a schematic diagram schematically showing the internal stress generated around the fitting recess of the housing body in a state where shrink fitting is completed.

[0050] Fig.21 It is a perspective cross-sectional view of a case body forming a part of a case in a permanent magnet embedded type motor according to another embodiment.

[0051] [Explanation of Symbols]

[0052] S: Axis

[0053] 1: Shell body (shell)

[0054] 1b: Fitting recess

[0055] 1b1: Fitting surface

[0056] 1b2: Wall

[0057] 1h: Flange

[0058] 1j1, 1j2: Two bosses (two thick wall parts)

[0059] 1j3, 1j4: Boss

[0060] L: Orthogonal line (arrangement direction)

[0061] Ed: Expansion direction

[0062] 1k: Multiple thin-walled parts

[0063] 2: Pump cover

[0064] 2a: Inlet

[0065] 2b: Spout

[0066] 3: Motor cover

[0067] 4: Base plate cover

[0068] 5: Rotation axis

[0069] U: Pump unit (trochoidal pump)

[0070] 11: Inner rotor (trochoid pump)

[0071] 12: Outer rotor (trochoid pump)

[0072] M: Permanent magnet embedded motor (drive source)

[0073] St:Stator

[0074] 20: stator core

[0075] 22: Teeth

[0076] 23: Slot

[0077] Rm: Rolled steel plate

[0078] Sp: Steel Plate

[0079] Rd: rolling direction

[0080] Ma: Central Area (Indicator)

[0081] ML: Mark (Indicator)

[0082] 30: Coil frame

[0083] 40: Coil

[0084] Rt: Rotor

[0085] 50: Rotor core

[0086] 51: Insertion hole

[0087] 52: V-groove-shaped recess

[0088] 53: Outer magnetic pole

[0089] 54: Filling holes

[0090] 55: Through hole

[0091] 60: Permanent magnet

[0092] G: Gap

[0093] 100: Shell body (shell)

[0094] 101: Thick wall part DETAILED DESCRIPTION

[0095] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0096] like Figures 1 to 3 As shown, a pump device including a permanent magnet embedded motor according to one embodiment includes: a housing body 1, a pump cover 2, a motor cover 3, a substrate cover 4, a rotating shaft 5, a pump unit U, a permanent magnet embedded motor M as a driving source, a circuit substrate CB, etc.

[0097] The pump unit U sucks in and discharges a fluid (here, oil), and is a trochoid pump including an inner rotor 11 and an outer rotor 12 .

[0098] like Figure 2 , Figure 8 , Fig. 9 As shown, the permanent magnet embedded motor M includes a stator St, a rotor Rt, and a housing (housing body 1, motor cover 3), and is a three-phase brushless motor with nine slots and six magnetic poles. The stator St includes a stator core 20, a coil frame 30, and a coil 40, and the rotor Rt includes a rotor core 50 and a permanent magnet 60.

[0099] Here, the housing body 1 and the motor cover 3 are part of the housing of the pump device, and also function as a housing of the permanent magnet embedded motor M, fixing the stator St and rotatably supporting the rotor Rt.

[0100] The housing body 1 is made of metal material, such as aluminum. Figure 2 , Figure 3 , Figures 5 to 7 As shown, it includes: a housing recess 1a for housing the pump unit U, a fitting recess 1b for embedding and housing the stator St, and a wall 1b for defining the fitting recess 1b. 2 , a communication passage 1c that connects the receiving recess 1a and the fitting recess 1b, an annular recess 1d, an annular recess 1e, an end face 1f, an end face 1g, a flange portion 1h, and four boss portions 1j 1 、1j 2 、1j 3 、1j 4 , a plurality of thin-walled portions 1k, and four threaded holes 1m into which screws b2 for fastening the substrate cover 4 and the motor cover 3 are screwed.

[0101] The housing recess 1 a defines a cylindrical inner peripheral surface and a bottom surface in order to rotatably house the pump unit U.

[0102] The fitting recess 1b is formed in a cylindrical shape centered on the axis S as the rotation center of the rotor Rt, and has a fitting surface 1b into which the annular portion 21 of the stator core 20 fits. 1 .

[0103] Wall 1b 2 The cylindrical shape is formed with the axis S as the center to define the fitting recess 1b. Figure 7 As shown, its wall thickness T 1 The plate thickness T is formed to be smaller than the flange portion 1h. 2 .

[0104] The communication passage 1 c is formed in a cylindrical shape centered on the axis S which is the rotation center line of the rotor Rt, and the rotating shaft 5 is inserted through the communication passage 1 c with a predetermined gap therebetween.

[0105] The annular recess 1d is formed in an annular shape centered on the axis S so that the lip seal Ls can be fitted therein.

[0106] The annular recess 1 e is formed in an annular shape centered on the axis S so that a bearing B1 that rotatably supports the rotary shaft 5 with a washer W interposed between the lip seal Ls is fitted therein.

[0107] The end surface 1 f is formed as a flat surface perpendicular to the axis S to engage with the pump cover 2 .

[0108] The end surface 1g is formed as a flat surface perpendicular to the axis S so as to closely engage with the motor cover 3 with the sealing material interposed therebetween.

[0109] The flange 1h is a member for fastening and fixing the pump device to the mounting surface of the object to be applied, and is formed so as to be connected to the wall 1b on the opening side of the fitting recess 1b. 2 The flange portion 1h is formed in a substantially rectangular flat plate shape that continuously expands around the periphery in a direction perpendicular to the axis S. The flange portion 1h is formed as a whole to be larger than the wall portion 1b of the fitting recess 1b. 2 Thick, like Figure 7 As shown, the two bosses 1j 1 、1j 2 The plate thickness T in the direction of the arrangement, that is, in the direction of the perpendicular line L perpendicular to the axis S 2 The wall portion 1b is formed to define the fitting recess 1b. 2 Wall thickness T 1 Thickness(T 2 >T 1 ).

[0110] In addition, the flange portion 1h is provided with a plurality of thin-walled portions 1k in a region deviating from a region through which the orthogonal line L passes. The plurality of thin-walled portions 1k can reduce the weight of the case body 1 while ensuring necessary mechanical strength.

[0111] In addition, in connecting the two bosses 1j 3 、1j 4 The straight line area, in the boss part 1j 3 , boss part 1j4 A thin-walled portion 1k is provided between the fitting recess 1b, and the plate thickness of the flange portion 1h in this region is formed to be larger than the plate thickness T 2 Small.

[0112] Four bosses 1j 1 、1j 2 、1j 3 、1j 4 The flange portion 1h is fastened to the joint surface of the pump device by fastening bolts (not shown). Figure 7 As shown, it is formed into a boss height (thickness) T 3 Cylindrical shape.

[0113] That is, the four bosses 1j 1 、1j 2 、1j 3 、1j 4 Formed to be thicker than the flange portion 1h (T 3 >T 2 ).

[0114] The housing body 1 constituting the above structure is heated to a predetermined temperature when the stator St is heat-fitted into the fitting recess 1b. During the heating process, the housing body 1 thermally expands, but the area with a large volume of material, that is, the area including the thick wall portion, expands more than other areas. 1 、1j 2 The overall thickness dimension (T 2 、T 3 ) is a wall portion 1b defining the fitting recess 1b. 2 Wall thickness T 1 Large wall thickness (T 2 、T 3 >T 1 ). In addition, the two bosses 1j 3 、1j 4 The thickness dimension as a whole in the arrangement direction is greater than the wall portion 1b defining the fitting recess 1b. 2 Wall thickness T 1 Thick, but thicker than the two bosses 1j 1 、1j 2 The thickness dimension in the arrangement direction is small and the wall is thin.

[0115] That is, the housing body 1 includes a wall portion 1b defining the fitting recess 1b. 2 , between the opening side of the fitting recess 1b and the wall 1b 2 The surrounding is continuous and formed to be larger than the wall portion 1b 2 Thick wall portion (flange portion 1h, four boss portions 1j1 、1j 2 、1j 3 、1j 4 , a plurality of thin-walled portions 1k), in a cross section including the axis S, Figure 7 The cross-sectional area of ​​the thick wall portion at the angle position shown is the largest.

[0116] Therefore, when the housing body 1 is heated, the boss portions 1j as the two thick wall portions 1 , boss part 1j 2 The change Δd of the inner diameter of the fitting recess 1b in the arrangement direction 1 Larger than the boss portion 1j as two thick wall portions 3 , boss part 1j 4 The change Δd of the inner diameter of the fitting recess 1b in the arrangement direction 2 In addition, Δd(=Δd 1 -Δd 2 ) is in the range of several μm.

[0117] That is, Figure 5 As shown, the boss portion 1j as two thick wall portions 1 , boss part 1j 2 The arrangement direction corresponds to the expansion direction Ed in which the change amount of the inner diameter of the fitting recess 1b is large when the shell body 1 is heated. In other words, the expansion direction Ed in which the change amount of the inner diameter of the fitting recess 1b is large when the shell body 1 is heated coincides with the angular position around the axis S where the cross-sectional area of ​​the thick wall portion becomes the largest in the cross-section including the axis S.

[0118] The pump cover 2 is formed of aluminum material, such as Figure 2 and Figure 3 As shown, the pump cover 2 is joined to the end surface 1f of the housing body 1 to cover the accommodating recess 1a, and includes a suction port 2a for sucking fluid and a discharge port 2b for discharging the pressurized fluid.

[0119] The pump cover 2 is joined to the end surface 1f of the housing body 1 in a state where the pump unit U is accommodated in the accommodation recess 1a, and is fastened and fixed by screws b1.

[0120] The motor cover 3 is formed of a resin material and is joined to the end surface 1g of the housing body 1 to cover the fitting recess 1b. Figure 2 and Figure 3 As shown, it includes: a through hole 3a centered on the axis S, an annular recess 3b, a fixing portion 3c for fixing the circuit board CB, a connector 3d for accommodating a terminal connected to the outside, and a circular hole for a screw b2 to pass through.

[0121] The through hole 3 a is formed so that the detection unit 5 b fixed to the end of the rotating shaft 5 can be inserted therethrough.

[0122] The annular recess 3b is formed in an annular shape centered on the axis S, and is used to fit and fix a cylindrical metal bracket 3e. The metal bracket 3e is fitted with and held by a bearing B2 that rotatably supports the rotating shaft 5.

[0123] The motor cover 3 is joined to the end surface 1g of the case body 1, joined to the substrate cover 4 from the outside, and fastened with screws b2 to be fixed therebetween.

[0124] The substrate cover 4 is formed of a metal plate or a resin material, and is fixed to the end surface 1g of the case body 1 by screws b2 in a state of sandwiching the motor cover 3 so as to cover the circuit board CB.

[0125] The rotating shaft 5 is made of metal and is formed into a cylindrical shape with the axis S as the center. Figure 2 , Figure 3 , Fig.16 As shown, it includes a connecting portion 5a having a double-sided width on one end side, a detection unit 5b fixed to the other end side, and a key groove portion 5c on the outer periphery.

[0126] Moreover, in the rotating shaft 5, the keyway portion 5c is embedded in the axial hole 57 of the rotor core 50 included in the permanent magnet embedded motor M, and the connecting portion 5a is connected to the inner rotor 11 of the pump unit U. In addition, the outer periphery is sealed by the lip-type seal Ls, and is supported by bearings B1 and bearings B2 to be able to rotate freely, so that the rotational force of the rotor Rt is transmitted to the inner rotor 11.

[0127] The detected unit 5b is formed by embedding a permanent magnet in a ring-shaped bracket in a manner that the N pole and the S pole are alternately exchanged around the axis S. Figure 2 As shown, the detected unit 5b is arranged to face the detection sensor C1 mounted on the circuit board CB.

[0128] Furthermore, the detected unit 5 b functions as a detection target of the detection sensor C1 that detects the rotation angle position of the rotating shaft 5 , that is, the rotor Rt.

[0129] like Figure 2 and Figure 3 As shown, the pump unit U includes an inner rotor 11 and an outer rotor 12 .

[0130] The inner rotor 11 is formed into a substantially star-shaped shape using a material such as steel or sintered steel, and defines an end surface that slides on the bottom wall surface of the receiving recess 1a of the housing body 1 and the inner wall surface of the pump cover 2. The inner rotor 11 is formed as an external gear having a tooth shape formed by a trochoid curve and including a fitting hole 11a, seven convex portions (mountains) and seven concave portions (valleys).

[0131] The fitting hole 11 a is formed so that the connecting portion 5 a of the rotating shaft 5 can be fitted therein.

[0132] The inner rotor 11 is rotated along the axis S through the rotating shaft 5. Figure 1 and Figure 2 Rotate in the direction of arrow A.

[0133] The outer rotor 12 is formed into a circular ring shape using a material such as steel or sintered steel, and is used to define an end surface that slides on the bottom wall surface of the receiving recess 1a of the housing body 1 and the inner wall surface of the pump cover 2. The outer rotor 12 is formed as an internal gear including a circular outer peripheral surface 12a, eight protrusions and eight recesses, and having a tooth shape that can mesh with the inner rotor 11.

[0134] The outer peripheral surface 12 a is in contact with the inner peripheral surface of the housing recess 1 a and is supported to be rotatable about an axis offset from the axis S.

[0135] The outer rotor 12 rotates at a slower speed than the inner rotor 11 while being linked to the rotation of the inner rotor 11 that rotates about the axis S.

[0136] The rotation of the inner rotor 11 and the outer rotor 12 causes the fluid to be sucked into the pump chamber from the suction port 2a and discharged from the discharge port 2b while being pressurized.

[0137] The circuit board CB includes components for controlling the driving of the permanent magnet embedded motor M, printed wiring, and various electronic components constituting the control circuit are mounted. Figure 2 As shown, a detection sensor C1 is installed facing the detected unit 5b.

[0138] The detection sensor C1 includes a plurality of Hall elements arranged in an arc shape centered on the axis S. The detection sensor C1 detects the magnetic pole position (rotation angle position) in the rotation direction of the rotating shaft 5, ie, the rotor Rt.

[0139] like Figure 8 and Fig. 9 As shown, the permanent magnet embedded motor M includes a stator St including a stator core 20 , a bobbin 30 , and a coil 40 , and a rotor Rt including a rotor core 50 and a permanent magnet 60 .

[0140] The stator core 20 is formed as a laminated body, which is formed by laminating a plurality of steel plates obtained by press-working a rolled steel plate containing a magnetic material. Fig.11 and Fig.12As shown, the stator core 20 includes: an annular portion 21, nine teeth 22, nine slots 23, and a plurality of cutout portions 24, wherein the nine teeth 22 serve as salient poles protruding from the annular portion 21 toward the center (axis S) and arranged at equal intervals in the circumferential direction, and the nine slots 23 are arranged at equal intervals in the circumferential direction.

[0141] The nine teeth 22 are formed in the same shape rotationally symmetrical about the axis S, and each includes a tip end surface 22 a defining an arc surface.

[0142] The nine tip surfaces 22 a are arranged on a cylindrical surface having a predetermined diameter, and are disposed so as to face the outer peripheral contour 50 a (outer peripheral magnetic pole surface 53 a ) of the rotor core 50 with a predetermined gap therebetween.

[0143] The nine grooves 23 are formed in the same shape rotationally symmetrical about the axis S, and each includes an opening 23 a having a predetermined width between the teeth 22 on both sides.

[0144] The cutout portion 24 is used as a positioning portion or an index for other parts during the lamination and pressing process of the stator core 20 .

[0145] Here, when explaining the manufacturing of the stator core 20, Fig.13 As shown, as the material, a rolled steel plate Rm is used, in which a steel block is rolled into a strip shape and then wound into a coil.

[0146] As the rolled steel plate material Rm, a rolled steel plate material having a plate thickness in the range of 0.2 mm to 0.5 mm is used.

[0147] In the press process, the rolled steel plate Rm is set and fed to the press machine Pm along the conveyor line TL. When the rolled steel plate Rm is stretched from a coiled state to a strip, the stretching direction of the strip corresponds to the rolling direction Rd.

[0148] Then, the steel sheet Sp forming the outline of the stator core 20 is punched by the punching machine Pm and manufactured sequentially. Then, the punched steel sheets Sp are stacked and pressed using a predetermined jig to bond them to each other. Therefore, the thickness of one steel sheet Sp is in the range of 0.2 mm to 0.5 mm.

[0149] Here, due to various factors such as residual stress and residual strain generated by rolling the rolled steel plate Rm and processing accuracy when punching the rolled steel plate Rm from a coiled state to a strip-shaped state, the stacked stator core 20 may be formed. Fig.12 As shown, there is a tendency that the outer diameter dimension in the direction of the straight line L2, that is, in the rolling direction Rd, becomes larger by an amount ΔD than the designed outer diameter dimension D. The value of ΔD is in the range of several μm.

[0150] Here, if Fig.11 and Fig.12 As shown, the direction of the straight line L2 (rolling direction Rd) is located at a position that passes through the center of the area where the cutout portion 24 is not provided at equal intervals on the outer peripheral surface of the annular portion 21 and is orthogonal to the axis S. In other words, the cutout portion 24 is provided at a position that is turned rightward by an angle θ and turned leftward by an angle θ from the straight line L2. Therefore, the rolling direction Rd of the steel plate Sp can be identified by using the central area Ma between the two cutout portions 24, 24 as an indicator. In addition, by marking the mark ML at the central position of the circumferential direction of the two cutout portions 24, 24, the mark ML can also be used as an indicator.

[0151] The bobbin 30 is formed into a two-part structure using a resin material having electrical insulation properties, and is assembled so as to sandwich the stator core 20 in the axis S direction.

[0152] The coil 40 has a concentrated winding structure wound around the nine teeth 22 via the bobbin 30 , and is electrically connected in three phases.

[0153] The rotor core 50 includes a laminated body formed by laminating a plurality of steel plates obtained by stamping a rolled steel plate containing a magnetic material, such as Fig.10 As shown, a cylindrical outer peripheral contour 50 a is defined, and the cylindrical outer peripheral contour 50 a faces the teeth 22 (top end surface 22 a ) of the stator core 20 with a predetermined gap therebetween.

[0154] like Fig.10 , Figures 14 to 16 As shown, the rotor core 50 includes: six insertion holes 51 arranged at equal intervals along the circumferential direction, six V-groove-shaped recesses 52 arranged at equal intervals along the circumferential direction, six outer peripheral magnetic pole portions 53 arranged at equal intervals along the circumferential direction, six filling holes 54 arranged at equal intervals along the circumferential direction, six through holes 55 arranged at equal intervals along the circumferential direction, support portions 56 arranged corresponding to each insertion hole 51, an axial hole 57 for the rotating shaft 5 to be embedded, and six long holes 58 arranged at equal intervals along the circumferential direction.

[0155] Here, the six insertion holes 51, the six V-groove-shaped recesses 52, the six peripheral magnetic pole portions 53, the six filling holes 54, the six through holes 55, the six support portions 56, and the eighty-six long holes 58 are respectively formed to be rotationally symmetrical with the axis S as the center. In addition, except for the long hole 58, all are formed to be linearly symmetrical with respect to the radial straight line DL. Therefore, one of them will be described below.

[0156] The insertion hole 51 is a region where the permanent magnet 60 is inserted and fixed, i.e., a buried region of the permanent magnet 60. Fig.16As shown, it is formed into a cross-sectional shape that is elongated in the perpendicular direction Pd with respect to the straight line DL in the radial direction of the rotor Rt.

[0157] Specifically, the insertion hole 51 is formed to include two wall surfaces 51 a and 51 b parallel to the vertical direction Pd and two convex curved surfaces 51 c protruding inwardly at both ends in the vertical direction Pd so as to be away from the through hole 55 .

[0158] The insertion hole 51 includes two convex curved surfaces 51 c , and when the permanent magnet 60 is inserted into the insertion hole 51 , gaps G are provided on both sides, and deviation of the permanent magnet 60 in the vertical direction Pd can be suppressed or prevented.

[0159] The V-groove-shaped recessed portion 52 is formed as a gap having a V-groove-shaped cross section tapering toward the axis S between the insertion holes 51 in the circumferential direction to divide the outer peripheral contour 50 a in the circumferential direction and define the outer peripheral magnetic pole portion 53 .

[0160] Furthermore, the V-groove-shaped recessed portion 52 functions as a magnetic flux barrier that suppresses or prevents leakage and short circuit of magnetic flux.

[0161] The outer magnetic pole portion 53 is a region where magnetic poles corresponding to the permanent magnet 60 inserted into the insertion hole 51 are generated. Fig.16 As shown, the magnetic field is line-symmetrical with respect to the radial straight line DL, and includes an outer peripheral magnetic pole surface 53 a between two V-groove-shaped recessed portions 52 , 52 .

[0162] The outer magnetic pole surface 53a is a curved surface having a curvature of 2 / φZ when the outer diameter dimension of the outer contour 50a, which is a cylindrical curved surface defining the outer contour 50a, is φZ, and faces the tip surface 22a of the tooth 22 with a predetermined gap therebetween.

[0163] The filling hole 54 is a region filled with an adhesive for fixing the permanent magnet 60 , and is formed on the radially inner side of the insertion hole 51 so as to communicate with the insertion hole 51 .

[0164] That is, after the permanent magnet 60 is inserted into the insertion hole 51 , the filling hole 54 is filled with adhesive, thereby bonding the radially inner surface of the permanent magnet 60 to the wall surface 51 a of the insertion hole 51 .

[0165] like Fig.16 As shown, the through hole 55 is formed to form a circular cross-sectional space on a plane perpendicular to the axis S between the insertion holes 51 in the circumferential direction and radially inward of the V-groove-shaped recessed portion 52 .

[0166] The through hole 55 functions as a flux barrier that suppresses or prevents leakage and short circuit of magnetic lines of force, and also functions as a positioning portion into which a jig for positioning the rotor core 50 is inserted when the permanent magnet 60 is assembled in the insertion hole 51 .

[0167] like Fig.15 and Fig.16 As shown, the support portion 56 is formed as a protruding piece protruding inward at the other open end of the insertion hole 51, and supports the end face 62 of the permanent magnet 60 inserted into the insertion hole 51, and positions the permanent magnet 60 in the direction of the axis S. Thus, the positioning and bonding work is completed only by inserting the permanent magnet 60 into the insertion hole 51.

[0168] like Fig.16 As shown, the shaft hole 57 is for the rotation shaft 5 to be engaged, and includes six protrusions 57 a that are engaged with the key grooves 5 c of the rotation shaft 5 .

[0169] The long hole 58 is formed to extend in a direction inclined with respect to the straight line DL on the radially outer side of the shaft hole 57. Furthermore, the long hole 58 allows elastic deformation of the peripheral area of ​​the protrusion 57a ​​when the rotating shaft 5 is fitted into the shaft hole 57. Thus, the fitting operation of the rotating shaft 5 can be smoothly performed.

[0170] like Fig.10 , Fig.14 , Fig.15 As shown, the six permanent magnets 60 are of the same shape, and are formed into a flat plate with a rectangular cross section that is long in the vertical direction Pd. Moreover, the six permanent magnets 60 are oriented so that the N poles and the S poles face each other in the radial direction (the straight line DL direction) of the rotor core 50, and are inserted at equal intervals in the circumferential direction around the axis S and in a manner that the poles facing the outside are alternately replaced. In addition, the permanent magnets 60 are provided with gaps G at both ends in the vertical direction Pd, and are inserted into the insertion holes 51 of the rotor core 50.

[0171] Here, since the gaps G are provided on both sides of the permanent magnet 60 , it is possible to prevent the magnetic force lines from being short-circuited from the N pole to the S pole of the permanent magnet 60 .

[0172] In addition, since a permanent magnet 60 with a simple flat plate shape is arranged corresponding to a peripheral magnetic pole portion 53, the structure can be simplified and the cost can be reduced compared to a structure in which a permanent magnet with a curved shape is arranged corresponding to a peripheral magnetic pole portion 53, or a structure in which a plurality of permanent magnets are arranged corresponding to a peripheral magnetic pole portion 53.

[0173] In the permanent magnet embedded type motor M having the above structure, referring to Figures 17 to 19 The fitting operation of the stator St to the case body 1 will be described.

[0174] First, if Fig.17 As shown, the case body 1 and the stator St are prepared. The stator St is formed by fitting the bobbin 30 into the stator core 20 and winding the coil 40 around the bobbin 30 .

[0175] Here, the rolling direction Rd (straight line L2) of the steel sheet Sp constituting the stator core 20 is oriented in a manner along the expansion direction Ed (orthogonal line L direction) of the housing body 1. This orientation is preferably a case where the expansion direction Ed (orthogonal line L) and the rolling direction Rd (straight line L2) are completely consistent, but it is not limited to this, and there is a certain allowable range in position deviation. For example, Fig.12 As shown, even if the direction deviates, it is permissible within the range of the angle θ, that is, the angle 2θ, which is rotated left and right with respect to the straight line L2. In this embodiment, the angle θ is about 40°.

[0176] Then, the housing body 1 is heated to a predetermined temperature. Fig.18 As shown in FIG. 1 , the stator core 20 is inserted into the fitting recess 1b in the direction of the axis S. Then, as shown in FIG. Fig.19 As shown, the stator St is completely inserted into the fitting recess 1b of the housing body 1 to a predetermined depth and left to cool to room temperature for a predetermined time, whereby the stator St is fixed in a tightly fitted state with respect to the fitting recess 1b.

[0177] As described above, the stator St is shrink-fitted to the housing body 1 by orienting the rolling direction Rd of the steel sheet Sp to the expansion direction Ed in which the inner diameter of the fitting recess 1b changes greatly when the housing body 1 as the housing is heated. Fig. 20 As shown, in the state cooled to room temperature after shrink fitting, a uniform compressive stress σ acts on the stator St (stator core 20) around the fitting recess 1b from the housing body 1. Therefore, local stress concentration in the housing body 1 and the stator core 20 can be suppressed or prevented.

[0178] As described above, according to the permanent magnet embedded motor M constituting the structure, it includes: a stator St, including a stator core 20 and a coil 40 for excitation, which are formed by stacking multiple steel plates Sp obtained by stamping a rolled steel plate Rm into a circular ring shape; a rotor Rt, which is arranged on the inner side of the stator St and includes a permanent magnet 60; and a metal shell (shell body 1), including a cylindrical fitting recess 1b centered on a specified axis S to embed the stator St, and the stator St is hot-mounted on the shell (shell body 1) by orienting the rolling direction Rd of the steel plate Sp to the expansion direction Ed in which the change in the inner diameter of the fitting recess 1b is large when the shell (shell body 1) is heated.

[0179] This makes it possible to suppress or prevent the occurrence of local stress (stress concentration) without increasing processing costs or complicating or increasing the size of the housing structure, thereby achieving a strong structure.

[0180] Furthermore, when the permanent magnet embedded motor M having the above-described structure is applied as a driving source of a pump device, a highly reliable pump device can be obtained without the risk of damage or the like.

[0181] Note that the operation of the interior permanent magnet motor M having the above-described structure is the same as that of a conventional interior permanent magnet motor, and thus the description thereof will be omitted here.

[0182] In the above embodiment, as the expansion direction in which the amount of change in the inner diameter of the fitting recess is large when the housing is heated, the flange portion 1h formed around the fitting recess 1b and the wall portion 1b arranged in the direction of the orthogonal line L orthogonal to the axis S near the flange portion 1h and larger than the wall portion 1b defining the fitting recess 1b are provided. 2 Thick two bosses 1j 1 、1j 2 Inside, two bosses 1j 1 、1j 2 The arrangement direction of is set as the expansion direction, but it is not limited to this.

[0183] For example, Fig.21 As shown, the following structure may also be adopted: the housing body 100 constituting a part of the housing includes: a wall portion 1b defining a fitting recess 1b 2 , between the opening side of the fitting recess 1b and the wall 1b 2 The surrounding is continuous and formed to be larger than the wall portion 1b 2 The two thick wall portions 101 , the opening end surface 102 , etc., a motor cover and a substrate cover (not shown) are fitted to and fixed to the opening end surface 102 of the housing body 100 .

[0184] Here, the two thick wall portions 101 are fitted into, for example, recessed portions of the application object, and play a role in positioning and fixing the housing (housing body 100 ) at a predetermined position of the application object.

[0185] In the above structure, the expansion direction Ed in which the inner diameter of the fitting recess 1b changes greatly when the housing body 100 is heated is angularly located about the axis S where the cross-sectional area of ​​the thick wall portion 101 becomes the largest in the cross section including the axis S, that is, Fig.21 The angular positions of the sections shown are consistent.

[0186] Thus, as long as the wall portion 1b defining the fitting recess 1b is included 2 The surrounding is continuous and formed to be larger than the wall portion 1b 2The structure of the thick-walled portion is not limited to the boss portion, and may be a thick-walled portion having other configurations.

[0187] In short, other various forms may be adopted as long as a volume with a certain expansion direction is formed in which the amount of change in the inner diameter of the fitting recess is large when the housing is heated.

[0188] In the embodiment, as a permanent magnet embedded motor including a stator and a rotor, the stator includes a plurality of teeth and slots arranged along the circumferential direction, the rotor includes a plurality of insertion holes arranged along the circumferential direction and a plurality of permanent magnets inserted in each insertion hole. The following permanent magnet embedded motor M is shown, which includes: a stator St and a rotor Rt, the stator St includes nine teeth 22 and slots 23, the rotor Rt includes six insertion holes 51 (that is, six permanent magnets 60), that is, the number of magnetic poles of the rotor Rt is six, and the number of teeth and slots of the stator St is nine.

[0189] However, the present invention is not limited to the above structure, and can also be applied to permanent magnet embedded motors having other structures in which the number of magnetic poles of the rotor is 2n (n is a natural number) and the number of teeth and slots of the stator respectively satisfies the condition of 3n (n is a natural number), and in specifications that deviate from the above conditions.

[0190] In the above embodiment, a case where a trochoid pump is used as a pump unit in a pump device using an interior permanent magnet motor M as a driving source is shown, but the present invention is not limited to this, and a vane pump or other types of pumps may be used.

[0191] As described above, the permanent magnet embedded motor of the present invention does not lead to an increase in processing costs, complication and enlargement of the casing structure, etc., and can suppress or prevent the generation of local stress (stress concentration), thereby obtaining a strong structure. Therefore, it can certainly be used as a driving source for a pump device, and can also be effectively used as a driving source for various devices.

Claims

1. A permanent magnet embedded motor, characterized in that: include: The stator includes a stator core formed into an annular shape by laminating a plurality of steel plates obtained by press working of rolled steel plates, and a coil for excitation; a rotor disposed inside the stator and including a permanent magnet; and The metal housing includes a cylindrical fitting recess centered on a predetermined axis to fit the stator. The stator is shrink-fitted to the housing by orienting the rolling direction of the steel plate to an expansion direction in which a change in the inner diameter of the fitting recess is large when the housing is heated.

2. The permanent magnet embedded motor according to claim 1, characterized in that: The housing includes a wall portion and a thick wall portion, the wall portion defining the fitting recess, the thick wall portion being continuous with the periphery of the wall portion on the opening side of the fitting recess and being formed to be thicker than the wall portion. The expansion direction coincides with an angular position around the axis at which the cross-sectional area of ​​the thick wall portion becomes maximum in a cross section including the axis.

3. The permanent magnet embedded motor according to claim 1, characterized in that: The housing includes a wall portion and two thick-walled portions, the wall portion delimiting the fitting recess, the two thick-walled portions being continuously formed around the wall portion and in a direction of an orthogonal line orthogonal to the axis on the opening side of the fitting recess and being thicker than the wall portion, The stator is shrink-fitted to the housing with the rolling direction being oriented as the arrangement direction of the two thick-walled portions.

4. The permanent magnet embedded motor according to claim 1, characterized in that: The housing includes: a wall portion defining the fitting recess; a flange portion formed around the wall portion on the opening side of the fitting recess; and two boss portions arranged along an orthogonal line direction orthogonal to the axis at the flange portion and thicker than the wall portion. The stator is heat-fitted to the housing with the rolling direction being oriented to be the arrangement direction of the two boss portions.

5. The permanent magnet embedded motor according to claim 4, characterized in that: The flange portion is formed to be thicker than the wall portion.

6. The permanent magnet embedded motor according to claim 5, characterized in that: The two boss portions are formed to be thicker than the flange portion.

7. The permanent magnet embedded motor according to claim 5, characterized in that: The flange portion includes a plurality of thin-walled portions in a region deviating from a region through which the orthogonal line passes.

8. The permanent magnet embedded motor according to claim 1, characterized in that: The stator includes an indicator indicating the rolling direction.

9. The permanent magnet embedded motor according to claim 1, characterized in that: The steel plate has a thickness of 0.2 mm to 0.5 mm.

10. The permanent magnet embedded motor according to claim 1, characterized in that: The housing is formed of aluminum material.

11. The permanent magnet embedded motor according to claim 1, characterized in that: The stator core has teeth and slots arranged in a circumferential direction. The stator includes the coil wound around the teeth via a resin bobbin.

12. The permanent magnet embedded motor according to any one of claims 1 to 11, characterized in that: The rotor includes: a cylindrical rotor core formed by laminating a plurality of steel plates obtained by press working a rolled steel plate and having insertion holes arranged in a circumferential direction; and the permanent magnets inserted in the insertion holes.

13. A pump device comprising: A pump unit for sucking and ejecting fluid; A rotating shaft connected to the pump unit; as well as a driving source for applying a driving force to the rotating shaft, The pump device is characterized in that The driving source is the permanent magnet embedded motor according to claim 12.

14. The pump device according to claim 13, characterized in that The pump unit is a trochoid pump including an inner rotor coupled to the rotating shaft and an outer rotor meshing with the inner rotor.

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