Motor and method for manufacturing the same

Abstract

To provide a motor and a method for manufacturing the same, which can shorten assembling time and reduce manufacturing cost.SOLUTION: A motor M comprises: a topped cylindrical case 1; a stator 2 having a winding 4 and fixed in the case 1; a heat sink 5 stacked on a top 1b side of the case 1 of the stator 2; and a substrate unit 6 staked on a top 1b side of the case 1 of the heat sink 5 to energize the winding 4. The heat sink 5 and the substrate 6 are held between the top 1b of the case 1 and the stator 2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a motor and a method for manufacturing a motor. [Background technology]

[0002] The motor is configured, for example, with a bottomed cylindrical case, a cylindrical stator fixed inside the case, a rotor rotatably inserted into the stator, a circuit board that passes current through windings provided on the stator, a heat sink that absorbs and dissipates heat from the circuit board, and a bearing holder that holds a bearing that supports the rotor (see, for example, Patent Document 1).

[0003] In a motor constructed in this manner, the stator is fixed to the innermost part of the case by shrink fitting, a bearing holder arranged on the case opening side of the stator is fixed to the case by shrink fitting, and a heat sink with a circuit board integrated therewith is fixed to the open end of the case by screws. A connector for connecting the circuit board to an external power source and exchanging signals with an external control device is also fixed to the heat sink by screws. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-195196 A Summary of the Invention [Problem to be solved by the invention]

[0005] In a motor configured as described above, at least two shrink fitting steps and three screw tightening steps are required for assembly of the motor. The shrink fitting step is time-consuming because it is necessary to heat the case to a high temperature, insert the stator or bearing holder into the case, and then cool it. The screw tightening step also takes time because it is necessary to tighten multiple screws.

[0006] As described above, the conventional motor requires a long time for assembly, which increases the manufacturing cost of the motor.

[0007] It is therefore an object of the present invention to provide a motor and a method for manufacturing the motor that can shorten the assembly time and reduce the manufacturing costs. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the motor of the present invention comprises a topped cylindrical case, a stator having windings and fixed within the case, a heat sink stacked on the top side of the stator case, and a board unit stacked on the top side of the heat sink case and which supplies electricity to the windings, with the heat sink and board unit being sandwiched between the top of the case and the stator.

[0009] With a motor configured in this manner, the stator can be fixed to the heat sink and substrate unit by simply shrink-fitting the stator into the case once, and no screw fastening is required. Therefore, compared to conventional motors which require two shrink-fitting and screw fastening processes, the number of shrink-fitting and screw fastening processes can be reduced.

[0010] The motor may also include a rotation stopper for the heat sink and the board unit relative to the stator, and the rotation stopper may include a stator-side convex portion provided on the heat sink and protruding toward the stator, a board-side convex portion provided on the heat sink and protruding toward the board unit, a concave portion provided on the stator and fitting with the stator-side convex portion, and a concave portion provided on the board unit and fitting with the board-side convex portion. With a motor configured in this manner, even if a configuration is adopted in which the stator is fixed to the case and the heat sink and the board unit are sandwiched between the stator and the top of the case, the rotation stopper can be realized without using screws, so the motor can be assembled at low cost, and the heat sink and the board unit can be positioned in appropriate positions, allowing the motor to be assembled appropriately. Also, even if a ball bearing is installed in the heat sink, the rotation of the heat sink can be restricted, so stable operation of the motor can be ensured.

[0011] The motor may include a rotor having a shaft and a detection magnet attached to the outer periphery of the shaft to detect the rotational position, the rotor being rotatably inserted into the stator, the top of the case and the board unit having a hole facing the top end of the shaft, and the detection magnet may be attached to the outer periphery of the top end of the shaft. With this motor, when the rotor is inserted into the case to which the stator, heat sink and board unit are attached, the upper and lower ends of the shaft can be fixed with a jig, making it easy to assemble the rotor, and the detection magnet for detecting the position of the rotor can be attached to the shaft near the board unit from the board unit side, making it easy to attach the detection magnet. In addition, the detection magnet can be attached to the rotor after the rotor is attached to the case, reducing assembly errors in the positional relationship between the mounted components and the detection magnet on the board unit.

[0012] Furthermore, the rotation stopper in the motor may include a pin member that fits into a hole provided in the stator along the axial direction, a hole provided in the heat sink along the axial direction, and a hole provided in the substrate unit along the axial direction. With a motor configured in this manner, the rotation stopper can be achieved by fitting one pin member into holes provided in the stator, the heat sink, and the substrate unit, eliminating the need for processing to provide pins in multiple components, further reducing manufacturing costs and easily achieving the rotation stopper.

[0013] The motor may also include an elastic body between the top of the case and the board unit that urges the heat sink and the board unit toward the stator. With a motor configured in this manner, the elastic body urges the heat sink and the board unit between the top of the case and the stator, so that the heat sink and the board unit can be fixed to the case without rattling.

[0014] The manufacturing method of the motor includes a process of assembling a stator assembly by first stacking a heat sink and a substrate unit on a stator having windings and electrically connecting the windings and the substrate unit, and a shrink fitting process of shrink fitting and fixing the stator of the stator assembly into a case.

[0015] According to the manufacturing method of the motor configured in this manner, by inserting a pre-assembled stator assembly into the case and shrink-fitting the stator into the case, not only the stator but also the heat sink and substrate unit can be fixed to the case together with the stator with only one shrink-fitting process, thereby reducing the number of shrink-fitting and screw tightening processes. Effect of the Invention

[0016] According to the motor and the method for manufacturing the motor of the present invention, the assembly time can be shortened and the manufacturing cost can be reduced. [Brief description of the drawings]

[0017] [Figure 1]1 is a vertical cross-sectional view of a motor according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view of a stator assembly according to the present embodiment. [Diagram 3] FIG. 11 is an enlarged cross-sectional view of a portion of a motor according to a modified example of the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention will be described below based on the embodiment shown in the drawings. As shown in Fig. 1, a motor M in this embodiment includes a cylindrical case 1 with a top, a stator 2 having windings 4 and fixed inside the case, a heat sink 5 stacked on the top 1b side of the case 1 of the stator 2, and a board unit 6 stacked on the top 1b side of the case 1 of the heat sink 5 and supplying electricity to the windings 4, and is a rotary motor that can rotate a rotor 7 rotatably inserted into the case 1 and the stator 2 by supplying electricity to the windings 4 of the stator 2.

[0019] Each part of the motor M will be described in detail below. As shown in Fig. 1, the case 1 has a cylindrical portion 1a, an annular top portion 1b with a hole 1b1 at the center provided at the upper end of the cylindrical portion 1a in Fig. 1, and a flange 1c protruding in the radial direction from the outer periphery of the lower end of the cylindrical portion 1a, and is formed into a topped cylindrical shape. In addition, the diameter of the lower portion is enlarged from a position slightly above the lower end in Fig. 1, which is the open end of the cylindrical portion 1a, and a step portion 1d is formed in the cylindrical portion 1a. Although not shown, the flange 1c has a plurality of holes that allow screws to be inserted and a plurality of mounting pieces that extend in the radial direction from the outer periphery and have mounting holes.

[0020] The stator 2 includes a cylindrical stator core 3 and a winding 4 attached to the stator core 3. The outer diameter of the stator 2 is equal to the outer diameter of the stator core 3, which has the largest outer diameter among the components constituting the stator 2, and is larger than the inner diameter of the case 1.

[0021] The stator core 3 includes a cylindrical yoke portion 3a, a plurality of teeth 3b that protrude radially from the inner circumference of the yoke portion 3a and are provided at equal intervals in the circumferential direction, and holes 3c as recesses that open from the upper end of the yoke portion 3a in FIG. 1. More specifically, the stator core 3 is composed of pieces that are divided in the circumferential direction so that each piece has teeth 3b. The winding 4 is wound around the teeth 3b of each piece via resin insulators 8 and 9 that are stacked vertically in FIG. 1. The stator 2 is assembled by assembling the pieces in which the winding 4 is wound around the teeth 3b in an annular shape. Note that it is sufficient to provide one or more holes 3c, but in the motor M of this embodiment, two holes 3c are provided at a distance from the yoke portion 3a in the circumferential direction.

[0022] 1, a busbar unit 11 having busbars (not shown) electrically connected to the same phase of the windings 4 wound around each tooth 3b is stacked and integrated with the stator 2. The busbar unit 11 has a plurality of terminals 11a protruding upward in FIG. 1 from each busbar.

[0023] 1 of the stator 2 configured in this manner, facing the top 1b of the case 1, a heat sink 5 is laminated thereon. The heat sink 5 is annular, and includes an annular groove 5a that is provided at the lower end in FIG. 1, which is the stator 2 side end, and that accommodates the insulator 8, the winding 4, and the bus bar unit 11 when laminated on the stator 2, a bearing accommodating portion 5b formed as an annular recess provided on the inner periphery at the lower end in FIG. 1, a terminal insertion hole 5c that opens from the upper end in FIG. 1 and communicates with the annular groove 5a, pins 5d and 5e as convex portions that protrude in the vertical direction from the outer periphery at the upper and lower ends in FIG. 1, a plurality of legs 5f that are arc-shaped in the axial view and extend downward from the outer periphery beyond the annular groove 5a, and an annular socket 5g that rises from the outer periphery at the upper end in FIG. 1, which is the top 1b side end of the case 1.

[0024] When the heat sink 5 is placed on the upper end of the stator 2 in Figure 1, the leg portion 5f is seated on the outer periphery of the yoke portion 3a of the stator core 3, and the lower end surface of the heat sink 5 in Figure 1, which is the inner periphery side of the annular groove 5a, is positioned slightly above the upper end of the stator 2.

[0025] The outer diameter of the annular groove 5a is smaller than the outer diameter of the yoke portion 3a of the stator core 3, the inner diameter of the annular groove 5a is approximately the same as or slightly smaller than the diameter of a circle inscribed in the tip of the tooth 3b of the stator core 3, and the depth of the annular groove 5a is deep enough to accommodate the insulator 8, the winding 4, and the busbar unit 11, so that the heat sink 5 does not interfere with the insulator 8, the winding 4, and the busbar unit 11 even when the heat sink 5 is placed on the stator 2. The terminal insertion hole 5c provided in the heat sink 5 is opened at the top of the annular groove 5a and at a position axially facing each terminal 11a of the busbar unit 11, and allows the terminal 11a to be inserted when the heat sink 5 is placed on the stator 2. Therefore, when the heat sink 5 is placed on the stator 2, each terminal 11a protrudes upward from the upper end of the heat sink 5 in FIG. 1.

[0026] The bearing accommodating portion 5b is formed as an annular recessed portion formed by expanding the inner diameter of the lower end side of the heat sink 5, which is on the stator 2 side, and accommodates a ball bearing 12 therein that rotatably holds the rotor 7.

[0027] Furthermore, in this embodiment, two pins 5d are provided from positions offset in the circumferential direction of the heat sink 5 toward the stator 2 side, which is the lower side in FIG. 1, and constitute a stator-side convex portion. The two pins 5d provided at the lower end of the heat sink 5 in FIG. 1 are provided on the outer side of a circle passing through the inner circumference of the multiple arc-shaped legs 5f when viewed from the axial direction, and are provided at positions that coincide with two holes 3c provided in the yoke portion 3a of the stator core 3, and when the heat sink 5 is placed on the stator 2, they are inserted into the corresponding holes 3c as recesses. In this way, each pin 5d is inserted into the corresponding hole 3c provided in the stator 2, so that the rotation of the heat sink 5 in the circumferential direction relative to the stator 2 is restricted. In this way, the rotation stop of the heat sink 5 relative to the stator 2 is formed by the pin 5d and the hole 3c. Although it is possible to prevent the rotation of the heat sink 5 relative to the stator 2 with only one pin 5d and one hole 3c, providing two or more restricts the circumferential rotation of the heat sink 5 relative to the stator 2 as well as the lateral movement of the heat sink 5 relative to the stator 2 in Fig. 1, thereby enabling the heat sink 5 to be stably prevented from rotating relative to the stator 2. In addition, two pins 5e are provided from offset positions in the circumferential direction of the heat sink 5 toward the board unit 6 side, which is upward in Fig. 1, and form board-side convex portions.

[0028] 1 of the heat sink 5. The outer diameter of the socket 5g is smaller than the outer diameter of the outer peripheral edge of the upper end of the heat sink 5. In addition, the maximum outer diameter of the heat sink 5 is smaller than the inner diameter of the cylindrical portion 1a of the case 1.

[0029] The board unit 6 arranged on the top 1b side of the case 1 of the heat sink 5 includes an annular printed circuit board 20, a ring-shaped housing 21 that is placed on the printed circuit board 20, and three connectors 22. Thus, the board unit 6 has a hole 6a in the center and has an overall ring shape.

[0030] The printed circuit board 20 is annular, and is mounted with wiring (not shown) electrically connected to terminals 11a of the busbar unit 11, electronic components such as switching elements and elements for detecting the position of the detection magnet 13 attached to the rotor 7, and connector terminals 20a (not shown) connected to an external power source and an external control device. The printed circuit board 20 is provided with holes 20b as recesses provided at positions corresponding to two pins 5e protruding from the upper end of the heat sink 5 in FIG. 1.

[0031] The outer diameter of the printed circuit board 20 is slightly smaller than the outer diameter of the socket 5g of the heat sink 5, and is larger than the inner diameter of the socket 5g. When the printed circuit board 20 is placed on the socket 5g of the heat sink 5, a gap G is formed between the lower end surface of the printed circuit board 20 in FIG. 1 and the upper end surface of the heat sink 5 in FIG. 1 by the height of the socket 5g. The gap G between the printed circuit board 20 and the heat sink 5 is filled with heat dissipation grease with high thermal conductivity to facilitate the transfer of heat from the printed circuit board 20 to the heat sink 5. In addition, when the printed circuit board 20 is placed on the socket 5g of the heat sink 5, the pins 5e as the board-side protrusions provided on the heat sink 5 are inserted into the holes 20b as the recesses provided on the printed circuit board 20, thereby restricting the rotation of the printed circuit board 20 relative to the heat sink 5 and the movement in the lateral direction in FIG. 1. Although it is possible to prevent the printed circuit board 20 from rotating relative to the heat sink 5 even if only one hole 20b and one pin 5e are provided, providing two or more of them makes it possible to restrict both the circumferential rotation and the lateral movement of the printed circuit board 20 relative to the heat sink 5.

[0032] The housing 21 has an annular top portion 21a and a cylindrical portion 21b that protrudes downward in Fig. 1 from the outer periphery of the top portion 21a toward the stator 2 side. As shown in Fig. 2, the top portion 21a has three arc-shaped connector insertion holes 21a1 that are equally spaced on the same circumference and extend along the circumferential direction, and an annular groove 21a2 that is provided on the outer periphery of the upper end of the top portion 21a in Fig. 1 and is located outer periphery further outward than the connector insertion holes 21a1.

[0033] Further, the cylindrical portion 21b has an outer diameter smaller than the inner diameter of the case 1, and is provided with a step portion 21b1 formed on the inner circumferential side with the inner diameter being smaller on the lower side in Fig. 1 which is the heat sink 5 side, and two holes 21b2 as recesses that open at positions facing the pin 5e of the step portion 21b1 and extend along the axial direction of the housing 21. The height from the step portion 21b1 of the cylindrical portion 21b to the lower end in Fig. 1 is lower than the height of the socket 5g of the heat sink 5 plus the height of the printed circuit board 20, and the inner diameter of the cylindrical portion 21b is larger than the outer diameter of the socket 5g.

[0034] Further, the outer diameter of the step portion 21b1 of the cylindrical portion 21b is slightly larger than the outer diameter of the printed circuit board 20, and the inner diameter of the step portion 21b1 is smaller than the outer diameter of the printed circuit board 20. Therefore, when the printed circuit board 20 is inserted into the housing 21, the outer periphery of the upper end of the printed circuit board 20 in FIG. 1 abuts against the step portion 21b1, and the further intrusion of the printed circuit board 20 into the housing 21 is restricted. Furthermore, when the housing 21 is placed on the heat sink 5 with the printed circuit board 20 placed on the socket 5g, the inner periphery of the lower end of the cylindrical portion 21b of the housing 21 in FIG. 1 fits into the outer periphery of the socket 5g of the heat sink 5, and the pins 5e as board-side protrusions inserted into the holes 20b as recesses of the printed circuit board 20 are inserted into the holes 21b2 as recesses.

[0035] In this way, by inserting the pin 5e into the hole 21b2, the housing 21 is restricted from rotating in the circumferential direction and from moving in the lateral direction in Fig. 1 with respect to the heat sink 5, but the number of the pins 5e, the holes 21b2, and the holes 20b of the printed circuit board 20 can be changed as desired. Furthermore, when the housing 21 is placed on the heat sink 5 with the printed circuit board 20 placed on the socket 5g, the printed circuit board 20 is sandwiched between the step 21b1 and the socket 5g, and the height from the step 21b1 of the cylindrical part 21b to the lower end in Fig. 1 is lower than the height of the socket 5g of the heat sink 5 plus the height of the printed circuit board 20, so that a gap is formed between the lower end in Fig. 1 of the cylindrical part 21b of the housing 21 and the upper end in Fig. 1 of the heat sink 5, which is the outer periphery of the socket 5g.

[0036] Further, annular groove 21a2 of housing 21 is provided at a position facing top portion 1b of case 1 in the axial direction, and an O-ring 15 is accommodated in annular groove 21a2 as an elastic body. A rubber cap 16 is attached to the inner periphery of housing 21 from the outside of the case to close the inner periphery side of top portion 1b of case 1 together with housing 21.

[0037] The connectors 22 are formed in a cylindrical shape having an arc shape when viewed in the axial direction, and are inserted into connector insertion holes 21a1 of the housing 21 and integrated with the housing 21. In addition, connector terminals 20a mounted on the printed circuit board 20 are inserted into each connector 22.

[0038] The heat sink 5 and the board unit 6 are stacked on the stator 2, and the printed circuit board 20 of the board unit 6 and the terminal 11a of the busbar unit 11 are connected to each other through wiring to assemble the stator assembly A. Then, the stator 2 is shrink-fitted into the case 1, and the heat sink 5, the board unit 6, and the O-ring 15 are sandwiched and held between the stator 2 fixed to the case 1 and the top 1b of the case 1. The O-ring 15 in an unloaded state has a cross section larger than the cross section of the annular groove 21a2 of the housing 21, and a part of it protrudes outward from the annular groove 21a2. When the board unit 6 is inserted into the case 1 and compressed against the top 1b, the O-ring 15 generates a resilient force that urges the heat sink 5 and the board unit 6 toward the stator 2. In this way, O-ring 15 is in close contact with top 1b of case 1 in a compressed state, and not only urges heat sink 5 and board unit 6 downward in Fig. 1 toward stator 2, but also seals between board unit 6 and case 1. Furthermore, cap 16 is attached to the inner periphery of housing 21 to close the inner periphery of housing 21, and therefore the opening at top 1b of case 1 is closed by O-ring 15, housing 21, and cap 16, preventing water and dust from entering case 1 from the opening.

[0039] 1, which is the open end of the cylindrical portion 1a of the case 1, is fitted with a bearing holder 17 that closes the open end of the cylindrical portion 1a of the case 1. The bearing holder 17 includes a protrusion 17a that fits on the open end side of the stepped portion 1d of the cylindrical portion 1a of the case 1, a flange 17b that protrudes radially from the outer periphery of the lower end of the protrusion 17a in FIG. 1 and faces the flange 1c of the case 1 in the axial direction, a shaft insertion hole 17c that passes through the protrusion 17a in the axial direction, and an annular groove 17d provided on the outer periphery of the protrusion 17a.

[0040] When the protrusion 17a of the bearing holder 17 is fitted into the case 1 until the flange 17b abuts against the flange 1c of the case 1, the O-ring 18 attached to the annular groove 17d on the outer periphery of the protrusion 17a is brought into close contact with the inner circumferential surface of the case 1 that is lower than the stepped portion 1d in FIG. 1, thereby sealing the space between the case 1 and the protrusion 17a.

[0041] Although not shown, flange 17b has holes that face a plurality of holes (not shown) provided in flange 1c of case 1, and is fixed to case 1 by screws that are inserted into said holes. Furthermore, although not shown, mounting pieces of the same shape as the mounting pieces provided on the outer periphery of flange 1c of case 1 are provided on the outer periphery of flange 17b of bearing holder 17 so as to protrude in the radial direction, and motor M can be attached to equipment (not shown) by using bolts or screws that are inserted into mounting holes provided in the mounting pieces of case 1 and the mounting pieces of bearing holder 17.

[0042] Furthermore, a bearing accommodating portion 17e for accommodating a ball bearing 19 is provided around the shaft insertion hole 17c at the upper end of the bearing holder 17 on the case 1 side in FIG.

[0043] The rotor 7 includes a shaft 7a, a cylindrical yoke 7b attached to the outer periphery of the shaft 7a, a plurality of permanent magnets 7c attached to the outer periphery of the yoke 7b so that N and S poles alternate on the outer periphery in the circumferential direction, and a detection magnet 13 attached to the outer periphery of the shaft 7a. The shaft 7a is inserted through a shaft insertion hole 17c of the bearing holder 17, into the stator 2, into the heat sink 5, and into the substrate unit 6, and the upper and lower outer peripheries are held by the heat sink 5 and the ball bearings 12, 19 attached to the bearing holder 17. Thus, the rotor 7 has the lower end of the shaft 7a in FIG. 1 protruding out of the case 1 through the shaft insertion hole 17c of the bearing holder 17, and can rotate in the circumferential direction around the axis within the case 1.

[0044] In this way, as shown in FIG. 1, the rotor 7 is supported by the heat sink 5, whose upper and lower axial ends are fixed to the case 1, and the ball bearings 12 and 19, which are attached to the bearing holder 17, and can rotate in the circumferential direction relative to the case 1 and the stator 2. The number of permanent magnets 7c provided on the rotor 7 is set according to the number of poles that can drive the motor M, depending on the number of slots between the teeth 3b, 3b of the teeth 3b of the stator 2. An annular detection magnet 13 is attached to the outer periphery of the upper end of the shaft 7a of the rotor 7, which is the top side of the case 1 in FIG. 1. The detection magnet 13 is used to detect the rotational position of the rotor 7, and is disposed in a position facing a magnetic sensor, such as a Hall element, which is one of the electronic components mounted on the printed circuit board 20.

[0045] The motor M is configured as described above, and the following describes a method of assembling the motor M. First, the insulators 8, 9 are placed above and below the teeth 3b of each piece constituting the stator core 3, and the windings 4 are wound around the insulators 8, 9. After that, the pieces are assembled into a circular shape to assemble the stator 2.

[0046] After assembling the stator 2, the busbar unit 11 is fixed to the top of the stator 2 using a fixing means such as a snap fit or thermal welding (not shown), and the lead wires of each winding 4 are electrically connected to the bus bars corresponding to each phase, thereby assembling the busbar unit 11 to the stator 2.

[0047] The heat sink 5, with the annular groove 5a facing the stator 2, is brought closer from above to the stator 2 to which the busbar unit 11 is assembled, and the insulator 8, the winding 4, and the busbar unit 11 are accommodated in the annular groove 5a of the heat sink 5. The two pins 5d of the heat sink 5 are inserted into the corresponding holes 3c of the stator core 3, and the terminals 11a of the busbar unit 11 are inserted into the terminal insertion holes 5c. Then, the legs 5f of the heat sink 5 are seated on the outer periphery of the yoke portion 3a of the stator core 3, and the heat sink 5 is assembled to the stator 2. When the heat sink 5 is assembled to the stator 2 in this manner, the heat sink 5 is guided by the pins 5d by the insertion of the pins 5d into the holes 3c, and the heat sink 5 is positioned at a proper position relative to the stator 2. The insertion of the pins 5d into the holes 3c restricts the heat sink 5 from rotating in the circumferential direction and moving laterally in FIG. 1 relative to the stator 2.

[0048] After the heat sink 5 is assembled above the stator 2, thermal grease is applied to the inner periphery of the socket 5g at the upper end of the heat sink 5 in FIG. 1, and the printed circuit board 20 is placed on the upper end of the socket 5g. When placing the printed circuit board 20 on the socket 5g, the pins 5e provided on the heat sink 5 are inserted into the holes 20b of the printed circuit board 20. In this way, when placing the printed circuit board 20 above the heat sink 5, the pins 5e are inserted into the holes 20b, and the printed circuit board 20 is guided by the pins 5e, so that the printed circuit board 20 is positioned at a proper position. Furthermore, the insertion of the pins 5e into the holes 20b restricts the printed circuit board 20 from rotating in the circumferential direction relative to the heat sink 5 and from moving in the lateral direction in FIG. 1. In this way, when the rotation of the printed circuit board 20 relative to the heat sink 5 is prevented, the rotation of the heat sink 5 relative to the stator 2 is also restricted, since the rotation of the heat sink 5 relative to the stator 2 is prevented. A structure may be adopted in which the rotation of the printed circuit board 20 is restricted directly against the stator 2 without going through the heat sink 5; however, the rotation stopper that restricts the rotation of the printed circuit board 20 directly against the stator 2 must be provided in a way that avoids the heat sink 5. Therefore, restricting the rotation of the printed circuit board 20 against the heat sink 5 makes it easier to secure the installation space for the rotation stopper and also simplifies the structure of the motor M.

[0049] In this embodiment, the thermal grease is applied to the upper end surface of the heat sink 5 on the inner periphery side of the socket 5g, thereby preventing the thermal grease from spilling out from between the heat sink 5 and the printed circuit board 20. Note that a thermally conductive heat dissipating sheet that adheres to the printed circuit board 20 and the heat sink 5 may be interposed between the printed circuit board 20 and the heat sink 5 instead of the thermal grease.

[0050] In this way, the printed circuit board 20 is placed at a proper position relative to the heat sink 5, and then the wiring (not shown) of the printed circuit board 20 is electrically connected to the terminal 11a by press-fitting, soldering, or welding. Furthermore, the housing 21 with the connector 22 integrated therein is brought close to the heat sink 5 on which the printed circuit board 20 is placed, from above the heat sink 5 with the inside facing the heat sink 5, and the pin 5e is inserted into the hole 21b2 formed in the cylindrical portion 21b. The housing 21 is brought close to the heat sink 5 while being positioned at a proper position relative to the heat sink 5 using the pin 5e as a guide, and the step 21b1 of the cylindrical portion 21b is brought into contact with the outer periphery of the upper end of the printed circuit board 20 in FIG. 1. Then, the housing 21 sandwiches the printed circuit board 20 between the step 21b1 and the socket 5g of the heat sink 5, and the insertion of the pin 5e into the hole 21b2 restricts the rotation in the circumferential direction and the movement in the lateral direction in FIG. 1 relative to the heat sink 5. In this way, when the board unit 6, which is composed of the housing 21 with the connector 22 integrated therein and the printed circuit board 20, is stopped from rotating relative to the heat sink 5 by inserting the pin 5e into the holes 20b, 21b2, the heat sink 5 is stopped from rotating relative to the stator 2, so that the rotation in the circumferential direction is also restricted relative to the stator 2. A structure in which the rotation of the board unit 6 is directly restricted relative to the stator 2 without the heat sink 5 may be adopted, but since a rotation stopper that directly restricts the rotation of the board unit 6 relative to the stator 2 must be provided to avoid the heat sink 5, restricting the rotation of the board unit 6 relative to the heat sink 5 makes it easier to secure the installation space for the rotation stopper and simplifies the structure of the motor M. After the assembly of the board unit 6 is completed, an O-ring 15 is fitted into the annular groove 21a2 formed on the outer periphery of the upper end of the housing 21 in FIG. 1 in the board unit 6.

[0051] When the heat sink 5 and the board unit 6 are attached to the stator 2 in this manner, the stator assembly A, which is an assembly composed of the stator 2, the heat sink 5 and the board unit 6, is completed, and the process of assembling the stator assembly A by attaching the heat sink 5 and the board unit 6 to the stator 2 is completed.

[0052] When the process of assembling the stator assembly A is completed in this manner, a shrink fitting process is performed to fix the stator 2 in the case 1. In the shrink fitting process, the case 1 is heated, the inner diameter of the case 1 is expanded by thermal expansion, the stator assembly A is inserted into the case 1, and the case 1 is cooled. Then, the case 1, whose inner diameter has expanded by thermal expansion, is cooled and contracts, and the case 1 tightens the outer periphery of the stator 2, i.e., the outer periphery of the stator core 3, so that the stator 2 is fixed to the case 1. When the stator assembly A is inserted into the case 1 in the shrink fitting process, when the stator 2 is inserted into the case 1 to a fixed position, the O-ring 15 is in a compressed state and comes into contact with the top 1b of the case 1. With the stator 2 fixed to the case 1, the heat sink 5 and the board unit 6 are urged toward the stator 2 side by the elastic force generated by the compressed O-ring 15 between the top 1b and the stator 2.

[0053] When the shrink fitting process is completed in this manner, the heat sink 5, the board unit 6, and the O-ring 15 are sandwiched between the stator 2 fixed to the case 1 and the top 1b of the case 1, and are fixed between the stator 2 and the top 1b by the elastic force exerted by the O-ring 15. Furthermore, when the board unit 6 is fixed to the case 1, the connector 22 of the board unit 6 protrudes from the opening in the top 1b of the case 1 to the outside of the case 1. Therefore, a connector (not shown) provided at the tip of a cord connected to an external power source or an external control device can be easily connected to the connector 22 outside the case 1.

[0054] As described above, once one shrink fitting process is completed, the stator 2, the heat sink 5, and the substrate unit 6 are fixed to the case 1, so that the stator 2, the heat sink 5, and the substrate unit 6 can be fixed to the case 1 without performing the shrink fitting process multiple times. Furthermore, once one shrink fitting process is completed, the heat sink 5 and the substrate unit 6 can be fixed to the stator 2 in a rotationally prevented state.

[0055] By providing the O-ring 15, a resilient force acts on the heat sink 5 and the board unit 6, which allows the heat sink 5 and the board unit 6 to be fixed to the case 1 without rattling between the top 1b and the stator 2, and also seals the gap between the case 1 and the board unit 6 to prevent water and the like from entering the motor M. However, the O-ring 15 can be omitted and the heat sink 5 and the board unit 6 can be sandwiched and fixed between the stator 2 and the top 1b. If it is not necessary to keep the inside of the motor M watertight, an elastic body without a sealing function, such as a wave washer or a leaf spring, may be used instead of the O-ring 15.

[0056] In addition, when the shrink fitting process is completed, the expanded case 1 cools and shrinks to its original diameter. However, since the maximum outer diameter of the heat sink 5 and the board unit 6 is smaller than the inner diameter of the case 1 at room temperature, the heat sink 5 and the board unit 6 do not interfere with the inner circumference of the case 1 after the case 1 has cooled and do not receive a radial load from the case 1.

[0057] After the shrink fitting process is completed, the ball bearing 12 is accommodated in the bearing accommodating portion 5 b of the heat sink 5 , and the ball bearing 12 is assembled to the heat sink 5 .

[0058] Next, the ball bearing 19 is accommodated in the bearing accommodating portion 17 e of the bearing holder 17 , and the ball bearing 19 is assembled to the bearing holder 17 .

[0059] 1 is inserted into the inner circumference of the ball bearing 12, and while fitting the bearing holder 17 into the lower open end of the case 1, the lower end of the shaft 7a is inserted into the inner circumference of the ball bearing 19. While aligning the hole in the flange 17b of the bearing holder 17 with the hole in the flange 1c of the case 1, the protrusion 17a of the bearing holder 17 is fitted into the case 1 until the flange 17b of the bearing holder 17 abuts against the flange 1c of the case 1, and the case 1 and the bearing holder 17 are fixed by screwing using the holes in the flange 17b and the holes in the flange 1c. When inserting the rotor 7 into the stator assembly A, the lower end of the case 1 is open, and both the top 1b of the case 1 and the base unit 6 have holes 1b1, 6a, allowing the shaft 7a to be inserted and the top and bottom of the shaft 7a of the rotor 7 can be fixed with a jig (not shown), making it easy to assemble the rotor 7.

[0060] After the fixing of the bearing holder 17 is completed, the rotor 7 is assembled to the case 1, and the detection magnet 13 is attached to the outer periphery of the upper end of the shaft 7a in FIG. 1, which faces the central hole of the annular housing 21 of the board unit 6. The top 1b of the case 1 and the board unit 6 have holes 1b1, 6a facing the shaft 7a, and if the inner diameter of the housing 21 at the top 1b and the board unit 6 is made sufficiently larger than the outer diameter of the detection magnet 13, the detection magnet 13 can be attached through the inner periphery of the top 1b and the board unit 6. When the detection magnet 13 is attached to the shaft 7a, it faces in the axial direction a magnetic sensor (not shown) mounted on the upper end of the inner periphery of the annular printed circuit board 20, so that the motor M can detect the rotational position of the rotor 7 by the magnetic sensor and transmit the detected rotational position of the rotor 7 to a control device (not shown). When an MPU that controls the motor M is mounted on the printed circuit board 20 and the rotational position of the rotor 7 is used only by the MPU, the rotational position does not need to be transmitted to an external control device or the like.

[0061] After the attachment of the detection magnet 13 to the shaft 7a is completed in this manner, the cap 16 that closes the opening of the housing 21 is attached to the housing 21, completing the assembly of the motor M. The cap 16 closes the opening of the housing 21 to prevent water, etc. from entering the motor M, so the motor M is provided with water resistance by the O-ring 15 and the cap 16.

[0062] As described above, the motor M of this embodiment comprises a topped cylindrical case 1, a stator 2 having windings 4 and fixed within the case 1, a heat sink 5 stacked on the top 1b side of the case 1 of the stator 2, and a board unit 6 stacked on the top 1b side of the case 1 of the heat sink 5 and which supplies electricity to the windings 4, with the heat sink 5 and the board unit 6 being sandwiched between the top 1b of the case 1 and the stator 2.

[0063] With the motor M configured in this way, the stator 2 can be fixed to the heat sink 5 and the substrate unit 6 simply by shrink-fitting the stator 2 into the case 1 once, and no screw fastening is required, so compared to conventional motors that require two shrink-fitting and screw fastening steps, the number of shrink-fitting and screw fastening steps can be reduced, shortening the time required for assembly and reducing manufacturing costs. Furthermore, with the motor M configured in this way, the screw fastening step can be eliminated, which reduces the need to manage the screw fastening torque and also reduces the need to take measures against contaminants that occur when the screws are fastened.

[0064] The motor M of this embodiment also includes a rotation stopper for the heat sink 5 and the board unit 6 with respect to the stator 2, and the rotation stopper includes a pin (stator side convex portion) 5d provided on the heat sink 5 and protruding toward the stator 2, a pin (board side convex portion) 5e provided on the heat sink 5 and protruding toward the board unit 6, a hole (recess) 3c provided on the stator 2 and fitted with the pin (stator side convex portion) 5d, and holes (recesses) 20b, 21b2 provided on the board unit 6 and fitted with the pin (board side convex portion) 5e. With the motor M configured in this way, even if a configuration is adopted in which the stator 2 is fixed to the case 1 and the heat sink 5 and the board unit 6 are sandwiched between the stator 2 and the top 1b of the case 1, the rotation stopper can be realized without using screws, so that the motor M can be assembled at low cost, and the heat sink 5 and the board unit 6 can be positioned at appropriate positions, allowing the motor M to be assembled appropriately. Furthermore, even if ball bearing 12 is provided on heat sink 5, the rotation of heat sink 5 can be restricted, so stable operation of motor M can be ensured. In motor M of this embodiment, ball bearing 12 is provided on heat sink 5, so there is no need to provide a separate bearing holder for holding ball bearing 12, and the number of parts is reduced, which is advantageous in terms of cost. Furthermore, there may be some play in the fit between the stator side convex portion of heat sink 5 and the concave portion of stator 2, and between the board side convex portion of heat sink 5 and the concave portion of board unit 6, but this does not pose a problem because heat sink 5 and board unit 6 are sandwiched between top 1b of case 1 and stator 2.

[0065] As described above, the rotation stopper for the heat sink 5 and the board unit 6 relative to the stator 2 is configured by the pins 5d and 5e provided on the heat sink 5, the hole 3c in the stator core 3, the hole 20b in the printed circuit board 20, and the hole 21b2 in the housing 21, but the pins may be provided in the stator 2 or the housing 21 of the board unit 6 instead of in the heat sink 5, and the holes may be provided in the heat sink 5. Also, the rotation stopper may be configured by a recess and a protrusion that fits into the recess, other than a combination of a pin and a hole. In this case, the recess and the protrusion may be provided between the stator 2 and the heat sink 5, and between the heat sink 5 and the board unit 6.

[0066] 3, a hole 5h may be provided in the heat sink 5 that faces the hole 3c provided in the stator core 3, the hole 20b in the printed circuit board 20, and the hole 21b2 in the housing 21 in the axial direction, and a pin member 30 may be fitted into these holes 3c, 5h, 20b, and 21b2 to form a rotation stopper. In this way, when the rotation stopper includes the pin member 30 that fits into the hole 3c provided in the stator 2 along the axial direction, the hole 5h provided in the heat sink 5 along the axial direction, and the holes 20b and 21b2 provided in the board unit 6 along the axial direction, the rotation stopper can be realized without using screws by fitting one pin member 30 into the holes 3c, 5h, 20b, and 21b2 provided in the stator 2, the heat sink 5, and the board unit 6. This not only allows the motor M to be assembled at low cost, but also eliminates the need to provide pins in multiple components, further reducing manufacturing costs and making it easier to realize the rotation stopper. Therefore, for example, a hole 5h can be formed in the heat sink 5 and the pin member 30 can be fitted into the hole 5h to provide the pins 5d, 5e of the heat sink 5 shown in Figure 1. Alternatively, the pin member 30 can be fitted into the hole 3c of the stator core 3 in advance, and the heat sink 5 and the substrate unit 6 to be stacked on the stator 2 can be assembled into the stator assembly A using the pin member 30 as a guide.

[0067] The motor M of this embodiment includes a rotor 7 having a shaft 7a and a detection magnet 13 attached to the outer periphery of the shaft 7a and used to detect the rotational position, and is rotatably inserted into the stator 2, and the top 1b of the case 1 and the board unit 6 have holes 1b1, 6a facing the top end of the shaft 7a, and the detection magnet 13 is attached to the outer periphery of the top end of the shaft 7a. According to the motor M configured in this manner, when the rotor 7 is inserted into the case 1 to which the stator 2, the heat sink 5, and the board unit 6 are attached, the upper and lower ends of the shaft 7a can be fixed with a jig, making it easy to assemble the rotor 7, and the detection magnet 13 for detecting the position of the rotor 7 can be attached to the shaft 7a near the board unit 6 from the board unit 6 side, making it easy to attach the detection magnet 13. In addition, the detection magnet 13 can be attached to the rotor 7 after the rotor 7 is attached to the case 1, so that an assembly error in the positional relationship between the mounted components on the board unit 6 and the detection magnet 13 can be reduced.

[0068] Moreover, the motor M of this embodiment includes an O-ring (elastic body) 15 between the top 1b of the case 1 and the board unit 6, which urges the heat sink 5 and the board unit 6 toward the stator 2. With the motor M configured in this manner, the O-ring (elastic body) 15 urges the heat sink 5 and the board unit 6 between the top 1b of the case 1 and the stator 2, so that the heat sink 5 and the board unit 6 can be fixed to the case 1 without rattling. Furthermore, in the motor M of this embodiment, the elastic body is the O-ring 15, so that it is possible to prevent water and the like from entering the motor M.

[0069] Furthermore, the manufacturing method of motor M in this embodiment includes a process of assembling stator assembly A by previously stacking heat sink 5 and substrate unit 6 on stator 2 having windings 4 and electrically connecting windings 4 and substrate unit 6, and a shrink fitting process of shrink fitting and fixing stator 2 of stator assembly A into case 1.

[0070] According to the manufacturing method of the motor M configured in this manner, by inserting the pre-assembled stator assembly A into the case 1 and shrink-fitting the stator 2 into the case 1, not only the stator 2 but also the heat sink 5 and the board unit 6 can be fixed to the case 1 together with the stator 2 in a single shrink-fitting process, so that the shrink-fitting process and the screw tightening process can be reduced, shortening the time required for assembly and reducing manufacturing costs. Also, in the manufacturing method of the motor M configured in this manner, the screw tightening process can be eliminated, which reduces the need to manage the screw tightening torque and also reduces the need to take measures against contaminants that occur when the screws are tightened.

[0071] Although the preferred embodiment of the present invention has been described in detail above, modifications, variations and changes can be made without departing from the scope of the appended claims. [Explanation of symbols]

[0072] 1 case, 1b top, 1b1 hole, 2 stator, 3 stator core, 3c hole (recess), 4 winding, 5 heat sink, 5d pin (protruding part on stator side), 5e pin (protruding part on board side), 5h hole, 6 board unit, 6a hole, 15 O-ring (elastic body), 20b hole (recess), 21b2 hole (recess), 30 pin member, A stator assembly, M motor

Claims

1. A cylindrical case with a top, a stator having a winding and fixed within the case; a heat sink laminated on the top side of the case of the stator; a substrate unit that is stacked on the top side of the case of the heat sink and that supplies current to the windings, The heat sink and the substrate unit are sandwiched between the top of the case and the stator. A motor characterized by:

2. a rotation stopper for the heat sink and the substrate unit relative to the stator; The rotation stopper is a stator-side protrusion provided on the heat sink and protruding toward the stator; and a board-side protrusion provided on the heat sink and protruding toward the board unit; a recess provided on the stator and fitted into the stator-side protrusion; a recess provided on the substrate unit and adapted to fit into the substrate-side protrusion; 2. The motor according to claim 1 .

3. a rotor having a shaft and a detection magnet attached to an outer periphery of the shaft and used to detect a rotational position, the rotor being rotatably inserted within the stator; the top of the case and the base unit have a hole facing the top end of the shaft, The detection magnet is attached to the outer periphery of the top end of the shaft.

2. The motor according to claim 1 .

4. a rotation stopper for the heat sink and the substrate unit relative to the stator; The rotation stopper has a pin member that fits into a hole provided in the stator along the axial direction, a hole provided in the heat sink along the axial direction, and a hole provided in the substrate unit along the axial direction.

3. The motor according to claim 2.

5. An elastic body is provided between the top of the case and the board unit, which urges the heat sink and the board unit toward the stator.

5. A motor according to claim 1 .

6. a step of assembling a stator assembly by stacking a heat sink and a substrate unit on a stator having a winding and electrically connecting the winding and the substrate unit; and a shrink fitting process for shrink-fitting the stator of the stator assembly into the case. A method for manufacturing a motor comprising the steps of:

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