JPH06205553A - Toroidal coil motor and stator positioning apparatus used therein - Google Patents

Abstract

PURPOSE:To make small the deviation of annular stator core center for axial center of a bearging member rotatably supporting a rotor. CONSTITUTION:A plurality of positioning areas more than three areas at the internal surface of an annular stator core 10 of a toroidal coil motor are not painted. When a positioning member moving member 37 having the internal cylindrical surface 37b coaxially arranged with the axial center of a bearing member 5 is moved in the axial direction, a positioning member 33 externally in contact with the conic external cylindrical surface 37a of the positioning member moving member 37 can be moved in the radius direction. In this case, the positioning member 33 is internally in contact with a plurality of positioning portions at the internal surface of the stator core 10. Therefore, the stator core 10 can be coaxially positioned against the bearing member 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toroidal coil motor used for rotating a mirror used as an optical deflector of a laser printer, and an annular stator core positioning device used for the toroidal coil motor.

[0002]

2. Description of the Related Art A laser printer is provided with a photosensitive drum, a rotary polygon mirror for scanning and irradiating a laser beam toward the photosensitive drum, and the like, for rotating the rotary polygon mirror. A toroidal coil motor is used.

FIG. 7 is a diagram showing a conventional toroidal coil motor. In FIG. 7, the bearing shaft 02 is fixed to the housing 01. A groove 02a forming a dynamic pressure air bearing is provided on the outer peripheral surface of the bearing shaft 02.
A rotary sleeve 04 of the rotor that rotates integrally with the rotary polygon mirror 03 is supported via a dynamic pressure air bearing on the outer peripheral surface of the bearing shaft 02 at the center. An annular permanent magnet 05 fixed to the rotating sleeve 04 is guided by a rotating magnetic field generated around the annular permanent magnet 06 to rotate integrally with the rotating sleeve 04.

At the time of starting and stopping the rotation, the pressure of the dynamic air bearing portion on the outer peripheral surface of the bearing shaft 02 is small, and the bearing shaft 0
2 and the rotating sleeve 04 are rotating while being in contact with each other, but as the rotating speed is increased, the pressure is increased and they are not in contact with each other. At this time, a gap S is formed between the surface of the bearing shaft 02 and the inner surface of the rotary sleeve 04. The pressure of the air layer in the gap S is uniform in the radial direction, but when an external force in a specific direction with respect to the radial direction is applied when the pressure is low and the rotation is started or stopped, the bearing shaft 02 and the rotary sleeve 04 are separated from each other. The contact time for contacting while rotating becomes longer. If the contact force is large, wear of the outer peripheral surface of the bearing shaft 02 and the inner peripheral surface of the rotary sleeve 04 is promoted, and the life is shortened.

One of the important causes of the external force in the specific direction, which causes the shortening of the life due to the wear of the bearing shaft 02 or the rotary sleeve 04, is the bearing shaft 0.
Since the position of the annular stator 06 is eccentric with respect to 2, the magnetic imbalance force is generated between the annular stator 06 and the annular permanent magnet 05 rotating about the bearing shaft 02. This magnetic imbalance force becomes an external force in a specific direction, that is, an external force in the radial direction. In order to suppress the generation of this magnetic unbalanced force, conventionally, a great deal of effort has been paid to the positioning of the stator 06 with respect to the bearing shaft 02.

Next, a conventional method for positioning the stator 06 will be described with reference to FIG. As shown in FIG. 8, a positioning jig 08 having a central hole that fits exactly into the bearing shaft 02 fixed to the housing 01 is inserted into the bearing shaft 02 in the axial direction. At this time, at the same time, the positioning jig 0
In No. 8, the outer peripheral surface also fits into the inner peripheral surface of the annular stator 06 and is fitted into the stator 06. The stator 06 is composed of an annular stator core 06a made of laminated plates and a toroidal coil around which wires 06b are wound at a plurality of circumferential positions. While the stator 06 is positioned with respect to the housing 01 through the positioning jig 08, the stator core 0 is screwed through the spacer 010 with the screw 09.
By fixing 6a to the housing 01 and removing the positioning jig 08, the stator core 06a is attached to the housing 01.
This means that they are positioned and fixed concentrically with respect to the bearing shaft 02.

[0007]

However, the positioning method using the above positioning jig has a problem that the positioning accuracy of the annular stator core 06a with respect to the shaft 02 is poor for the following three reasons. First, since the thickness of the insulating material adhered to the surface of the stator core 06a by coating or the like varies greatly, the position of the stator core 06a itself cannot be known. Secondly, the positioning jig 08
Is made of an elastic material such as Teflon so as not to damage the wire 06b. Therefore,
When the stator positioning jig 08 is inserted or fitted into the bearing shaft 02, the positioning jig 08 is deformed.
Thirdly, since the stator core 06a itself is not positioned by the positioning jig, but the stator core 06a is wound with the wire 06b and is positioned through the wire 06b, the positional accuracy is not uniform. It is affected by the gap generated between the wire 06b and the stator core 06a.

In view of the above circumstances, the present invention provides the following (O01)
The content described in is the subject. (O01) To reduce the amount of eccentricity of the center of the annular stator core with respect to the axis of the bearing member that rotatably supports the rotor.

[0009]

The present invention devised to solve the above problems will now be described. The elements of the present invention are to facilitate correspondence with the elements of the embodiments described later. Note that the reference numerals of the elements of the embodiments are enclosed in parentheses. The reason why the present invention is described in association with the reference numerals of the embodiments described later is to facilitate the understanding of the present invention and not to limit the scope of the present invention to the embodiments.

In order to solve the above problems, the first of the present application
The toroidal coil motor of the invention comprises a housing (1),
A bearing member (5) arranged at a predetermined position inside the housing (1), a rotor rotatably supported by the bearing member (5), and the bearing member (5) around the rotor.
An annular stator (7) positioned and fixed to the housing (1) concentrically with the axis of the stator (7), the stator (7) having an annular stator core (1) coated with insulation.
0) and a toroidal coil motor composed of a wire (11) wound around the stator core (10) at a plurality of positions in the circumferential direction, characterized by having the following requirement (Y01): (Y01) The annular stator core (1
A plurality of positioning portions (10a) are provided at three or more locations on the inner surface other than the portion (0) where the wire (11) is wound, and the positioning portion (10a) is not painted.

In order to solve the above-mentioned problems, the stator positioning device of the second invention of the present application comprises a housing (1), a bearing member (5) arranged at a predetermined position inside the housing (1), A rotor rotatably supported by a bearing member (5), and an annular stator (7) positioned and fixed to the housing (1) around the rotor and concentric with the shaft center of the bearing member (5). The stator (7) has a toroidal coil motor including an annular stator core (10) coated with insulation and wires (11) wound around a plurality of circumferential positions of the stator core (10). In the positioning device of the stator (7) used for determining the fixing position of the stator (7) to the housing (1) when manufacturing the, the following requirements (Y02) to (Y04 (Y02) Positioning device bodies (30) and (Y03) supported at a predetermined position with respect to the axis of the bearing member (2).
Positioning that is supported by the positioning device body (30) and also supports a positioning member (33) that is radially movable at positions corresponding to the plurality of positioning portions (10a) on the annular inner surface of the stator core (10). Member support members (31), (Y04) The positioning member (3)
3) has a conical outer cylindrical surface (37a) capable of abutting and a inner cylindrical surface (37b) movable in the axial direction in a state of being arranged concentrically with the shaft center of the bearing member (5), A positioning member moving member (37) supported by the positioning device body (30) so as to be movable in the axial direction.

In order to solve the above-mentioned problems, the stator positioning device of the third invention of the present application is the same as the stator positioning device of the second invention, with the following requirement (Y05).
To (Y07), (Y05) the positioning member (33) is composed of a sphere, (Y05)
06) The bearing member (5) is constituted by a bearing shaft (5) having a groove for forming a dynamic pressure air bearing on the outer peripheral surface, (Y07) A position concentric with the shaft center of the bearing member (5). The inner cylindrical surface (3
7b) is composed of an inner cylindrical surface (37b) slidably fitted to the bearing shaft (5).

[0013]

Next, the operation of the present invention having the above features will be described. In the toroidal coil motor of the first invention of the present application having the above-mentioned characteristics, the plurality of positioning portions (10a) at three or more locations on the inner surface of the annular stator core (10) are not painted. Therefore, the positioning portion (10
If a) is correctly positioned, the stator core (10)
Can be accurately positioned. Therefore, by positioning the position of the positioning portion (10a) concentrically with the shaft center of the bearing member (5), the stator core (10) is concentric with the shaft center of the bearing member (5) and the housing (1). Can be fixed to. Therefore, since the concentricity between the stator core (10) and the rotor is good, the magnetic imbalance force generated between the stator core (10) and the rotor is small, and the influence of the external force in the radial direction becomes strong. The contact time between the bearing member (5) and the rotor is short even at the time of starting and stopping, and wear of the bearing member (5) and the rotor is small.

In the stator positioning device of the second invention of the present application, the positioning member moving member (37) having the inner cylindrical surface (37b) arranged concentrically with the shaft center of the bearing member (5) is used as the shaft. When moved in the direction, the positioning member (33) circumscribing the conical outer cylindrical surface (37a) of the positioning member moving member (37) can be moved in the radial direction. At this time, the positioning member (33) has a plurality of positioning portions (10a) on the inner surface of the stator core (10).
Inscribe. Therefore, the stator core (10) is positioned concentrically with the bearing member (5).
That is, since the bearing member (5) and the stator core can be fixed to the housing (1) in a concentric state, the rotor supported by the bearing member can be rotated concentrically with respect to the stator (7). it can.

Further, in the stator positioning device of the third invention of the present application, the positioning member (33) is composed of a sphere (33), and the bearing member (5) forms a dynamic pressure air bearing on the outer peripheral surface. It is constituted by a bearing shaft (5) provided with a groove. The positioning member moving member (3
Since the inner cylindrical surface (37b) of 7) is slidably fitted to the bearing shaft (5), it can be moved in the axial direction. In the third invention, the bearing shaft (bearing member)
It is easy to arrange the inner cylindrical surface of the positioning member moving member (37) concentrically with respect to (5). When the positioning member moving member (37) is moved in the axial direction, the sphere (33) circumscribing the conical outer cylindrical surface (37a) of the positioning member moving member (37) can be moved in the radial direction.
At this time, the sphere (33) corresponds to the stator core (10).
And inscribes a plurality of positioning portions (10a) on the inner surface of the. At this time, the stator core (10) is arranged concentrically with the bearing member (5).

[0016]

EXAMPLE An example of the toroidal coil motor of the present invention will be described below. FIG. 1 is a sectional view showing an embodiment of the present invention. Reference numeral 1 denotes a cylindrical housing 1, and a shaft flange 2 is firmly fixed and attached to a bottom outer surface of the housing 1 by a screw 2a. The open end side of the housing 1 is closed by a cover 3, and the cover 3 is fixed to the housing 1 with a screw 4. A window glass 3a is attached to a side portion of the cover-3. The bearing shaft 5 as a bearing member penetrates the bottom wall 1a and is vertically attached to the shaft flange 2 by means such as press fitting. On the peripheral surface of the bearing shaft 5, a large number of cut grooves 5a for generating dynamic pressure are formed side by side in the circumferential direction.

An annular stator 7 is supported concentrically with the bearing shaft 5 at the upper ends of a plurality of spacers 6 whose lower ends are supported on the inner surface of the bottom wall 1a. Stoppers 8 are formed in the stator 7 at three locations in the axial direction, and screws 9 are passed through the stop holes 8 and the through holes of the spacer 6, so that the front end (lower end) of the screw 9 is The stator 7 is screwed into the bottom wall 1a of the housing 1, and the stator 7 is firmly fixed to the housing 1 via the spacer 6, and is correctly positioned concentrically with respect to the bearing shaft 5. The stator 7 includes an annular stator core 10 made of an annular laminated plate, and a stator core 1 as shown in FIG.
It is made of a toroidal coil formed by winding a wire 11 around a plurality of circumferential positioning portions 10a of 0.

Although the stator 7 is coated on almost the entire surface thereof, a plurality of positioning portions 10a at three or more positions on the inner peripheral surface of the portion of the stator core 10 where the wire 11 is not wound are positioned as described later. Unpainted because of the need for. Alternatively, the coating material at the positioning portion 10a is removed even if it is once coated.

The rotor R is arranged with a slight gap S1 provided between the bearing shaft 5 and the outer peripheral surface thereof. Rotor R
Has a cylindrical rotary sleeve 12, a yoke 13 is adhered to a small diameter portion 12a of the lower portion of the rotary sleeve 12, and is joined to the outer peripheral surface of the yoke 13 to form an annular permanent magnet 14.
Is inset. The permanent magnet 14 has N poles and S poles set at opposite pole positions different by 180 °. A balance ring 15 is fitted to the small diameter portion 12a of the rotary sleeve 12 from below.

A rotary polygon mirror 17 having an outer peripheral surface formed into a mirror surface is coaxially fitted in an upper portion of the rotary sleeve 12 so as to come into contact with the upper surface of the flange 16 in the central portion of the bearing shaft 5, and the rotary polygon mirror is formed. A cap 17 is pressed and fixed to the flange 16 by a cap 18. Rotate the rotary polygon mirror 17 with the cap 18 by screwing the three holes formed in the flange portion of the cap 18 in the ring structure and the holes formed in the rotary polygon mirror 17 corresponding to these holes through the screws 18a into the flange 16 through the screws 18a. It is fixed to the sleeve 12. Bearing shaft 5
A space S2 is formed by the cap 18 and the rotary sleeve 12 above. The rotor R is composed of the elements indicated by the reference numerals 12 to 18.

Screw holes are formed in the stator core 10 at three other positions, and a screw 20 is screwed into the screw hole via a stud 19, and a board 21 is provided between the stud 19 and the head of the screw 20. The substrate 21 is attached to the stator core 10 by sandwiching. On the substrate 21, a detection circuit for detecting an output signal of the magnetic detection element 22 formed of a hall element or the like provided near the rotation region of the permanent magnet 14 is formed.

Next, an embodiment of the positioning device of the present invention for correctly positioning the stator 7 concentrically with respect to the bearing shaft 5 and firmly fixing it to the housing 1 will be described.
FIG. 3 is a diagram showing the toroidal coil motor before the stator core 7 is positioned and fixed, and FIG. 4 is a diagram showing the positioning device A thereof. In FIG. 3, the shaft flange 2 to which the bearing shaft 5 is attached is fitted into the housing 1 and placed on the workbench D. In FIG. 4, the main body 30 of the positioning device A is simply placed on the upper end surface of the housing 1. The positioning device body 30 has a cylindrical wall 30a and a ceiling wall 30b, and is mounted on the housing 1 substantially coaxially with the bearing shaft 5. As shown in FIG. 5, a central hole 30c is formed in the center of the ceiling wall 30b, and three driver insertion holes 30d and three stator pressing rod insertion holes 30e are formed around the central hole 30c on the same circumference. It is provided in.

In FIG. 4, a ball support member (that is, a positioning member support member) 31 is provided in the center hole 30c.
It is fitted and fixed. The sphere support member 31 is a substantially cylindrical member having a disc-shaped top wall provided at the upper end, and the inner surface of the cylinder has a constant diameter, but the outer surface thereof has a tapered conical tapered surface as it goes downward. Is formed in. Three holding holes 32 are opened in the thin portion below the ball support member 31 at equal intervals in the circumferential direction in the radial direction. Steel balls (that is, positioning members) 33 are loosely fitted one by one into the holding holes 32. The movement of the steel ball 33 outward in the radial direction within the holding hole 32 causes a leaf spring that presses the steel ball 33 inward from the outer surface of the ball support member 31 (that is, a steel ball fall prevention member). It is regulated by 34. Further, the movement of the steel ball 33 inside the holding hole 32 is restricted by a ball moving member described later.

A female screw 31a is formed in a hole opened in the axial direction at the center of the ceiling of the ball support member 31. A handle shaft 35 having a male screw 35a cut is passed through the female screw 31a. The first clamp nut 36 is screwed into the handle shaft 35 from below to the upper position, and then the ball moving member 37 for displacing the steel ball 33 in the radial direction is inserted into the handle shaft 35 from below. The second clamp nut 38 is screwed into the lower end portion of the handle shaft 35 so that the ball moving member (that is, the positioning member moving member).
37 is fixed to the handle shaft 35.

The sphere moving member 37 is a substantially cylindrical member. The outer peripheral surface 37a has an upper portion having an outer diameter that fits into the inner cylindrical surface of the sphere supporting member 31, and a lower portion has a tapered conical tapered surface. Has been formed. The inner peripheral surface 37b of the substantially cylindrical sphere moving member 37 has a small diameter inner peripheral surface 37c at the upper end. The small-diameter inner peripheral surface 37c is a portion through which the handle shaft 35 penetrates, and upper and lower end surfaces thereof are sandwiched by the first and second clamp nuts 36 and 38. The lower portion of the inner peripheral surface 37b is fitted to the outer peripheral surface of the bearing member 5 so as to be movable in the axial direction. By this fitting, the ball moving member 37 is held concentrically with the bearing shaft 5. Therefore, the tapered surface of the outer peripheral surface 37a of the ball moving member 37 is held concentrically with the bearing shaft 5. The outer peripheral surface 37a held at the position concentric with the bearing shaft 5 moves downward to push the steel ball 33 outward. Therefore, the position of the outer side surface of the steel ball 33 extruded outward is arranged at the concentric position with the axial center of the bearing shaft 5.

Pressing rods 39 are slidably inserted into the three stator pressing rod insertion holes 30e of the ceiling wall 30b of the positioning device main body 30, respectively. Presser bar 3
A compression spring 40 is arranged between the ring-shaped spring support member 39 a fixed to the position 9 and the back surface of the ceiling wall 30 b of the positioning device body 30. The pressing bar 39 is pressed downward by the compression spring 40, and the lower end surface of the pressing bar 39 presses the upper end surface of the stator core 10 to loosely fix the stator core 10 on the spacer 6.

Next, a method of positioning the stator 7 with respect to the bearing shaft 5 using the positioning device A will be described. In the state shown in FIG. 4, since the ball moving member 37 is at the upper position, the steel ball 33 is pushed inward by the steel ball fall prevention member 34 from the outside. Further, at this position, the position of the steel ball 33 in the circumferential direction is equal to that of the stator core 1.
Positioning portion 10a of the cylindrical inner peripheral surface of No. 0 where the wire 11 is not wound and is not covered with the coating material (see FIG. 2)
It is arranged corresponding to the position of.

When the handle of the handle shaft 35 is rotated, the handle shaft 35 moves forward and descends, and the ball moving member 37 also descends while rotating. The conical outer cylindrical surface 37a of the ball moving member 37 causes three or more steel balls 33 to move radially outward in the same plane perpendicular to the axis of the bearing shaft 5. In this case, since the conical outer cylindrical surface 37a that comes into contact with the surface arranged inside each steel ball 33 is concentric with the bearing shaft 5, the surface arranged outside each steel ball 33 (stator core 10). The surface facing the inner surface) is also displaced outward while maintaining the position concentric with the axial center of the bearing shaft 5.

When the handle shaft 35 and the ball moving member 37 are lowered to the state shown in FIG. 6, the plurality of steel balls 33 come into contact with the cylindrical inner peripheral surface of the stator core 10. At this time, the inner peripheral surface of the stator core 10 is arranged concentrically with the axial center of the bearing shaft 5 by the outer surface of the steel ball 33. While maintaining this state, a screwdriver 9 (not shown) is passed through the driver insertion hole 30d (see FIG. 5) formed in the positioning device main body 30 and the spacer 6 is screwed.
The stator 7 is firmly fixed to the housing 1 via.

Next, the operation of the toroidal coil motor composed of the stator 7 positioned as described above will be described. A magnetic attraction force acts between the permanent magnet 14 and the stator 7. This attractive force acts so that the opposing positions of the permanent magnet 14 and the stator 7 do not shift in the axial direction of the motor. That is, when the permanent magnet 14 moves upward with respect to the stator 7, the attraction force works to pull back the permanent magnet 14 downward, and conversely, the permanent magnet 14 moves downward with respect to the stator 7. Then, the attraction force works to pull back the permanent magnet 14 upward. Therefore, the permanent magnet 14 faces the stator 7 at a predetermined position in the axial direction and is settled down. That is, the permanent magnet 14 and the station
A magnetic thrust bearing is formed with the rotor 7.

An electric current is applied to the wires 11 of the stator 7 at a plurality of positions, and the permanent magnets 14 and the rotating sleeve 12 of one body.
When is rotated, a predetermined small gap S1 is opened between the rotary sleeve 12 and the bearing shaft 5, and the rotary sleeve 12 can be floated in the air and rotated. When the rotation speed becomes high, the bearing pressure in the gap S1 between the bearing shaft 5 and the rotary sleeve 12 increases, and the rotation of the rotary sleeve 12 becomes more stable. In this state, the bearing shaft 5 and the rotary sleeve 12 are arranged concentrically. When the rotary sleeve 12 moves upward, the space S shown in FIG.
The pressure of 2 is reduced and the cap 18 integral with the rotating sleeve 12 is pulled downward. When the rotary sleeve 12 moves downward, the pressure in the space S2 shown in FIG. 1 rises, and the cap 18 integral with the rotary sleeve 12 is pushed upward. Therefore, the space S2 acts to prevent the vertical movement of the rotary sleeve 12.

Although the dynamic pressure is small when the rotary sleeve 12 is started and stopped, the concentricity of the rotary sleeve 12 and the stator core 10 is high, so that the permanent magnet 14 and the stator core 10 are connected.
The magnetic unbalanced force with the tacoa 10 is kept small. Therefore, the contact time between the rotary sleeve 12 and the bearing shaft 5 is short, and the contact force is also small, so that the bearing shaft 5 and the rotary sleeve 12 are less worn.

(Modifications) The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above-mentioned embodiments, and within the scope of the gist of the present invention described in the claims. It is possible to make various small design changes. For example, instead of fixing the bearing shaft 5 to the housing 1 via the shaft flange 2 with the screw 2a, the bearing shaft 5 can be formed by cutting into the housing 1 and one body. Further, the number of steel balls 33 may be three or more, and the number is not limited to three.
Further, the steel ball 33 is immovably supported in the holding hole 32 in the lower portion of the ball support member 31, and the holding hole 32 is provided.
It is also possible to give the cylindrical portion having the elasticity which is displaceable in the radial direction. Furthermore, instead of the steel ball 33, it is possible to use a positioning member having a uniform size in the radial direction (radial direction of the bearing shaft 5). In this case, instead of the ball support member 31, an appropriate positioning member support member that supports the positioning member so as to be movable in the radial direction may be adopted.

[0034]

The present invention described above has the following effects (E01). (E01) The eccentric amount of the annular stator core can be reduced with respect to the axis of the bearing member that rotatably supports the rotor of the toroidal coil motor. Therefore, since the magnetic imbalance force generated between the annular stator core and the rotor can be reduced, the contact force and contact time of the bearing member and the rotor are reduced, wear of the bearing member can be reduced, and the life of the bearing member can be extended. .

[Brief description of drawings]

FIG. 1 is a side sectional view of an embodiment of the toroidal coil motor of the present invention.

FIG. 2 is a plan view of a stator used in the above embodiment.

FIG. 3 is a diagram showing a state before positioning the stator of the embodiment of the toroidal coil motor of the present invention.

FIG. 4 is an explanatory view of an embodiment of a positioning device for a stator used in a toroidal coil motor according to the present invention.

5 is a view seen from the line VV of FIG. 4;

FIG. 6 is an operation explanatory view of the stator positioning device shown in FIG. 4;

FIG. 7 is an explanatory diagram of a conventional toroidal coil motor.

FIG. 8 is an explanatory diagram of a positioning method of a stator used in a conventional toroidal coil motor.

[Explanation of symbols]

A ... Positioning device, 1 ... Housing, 5 ... Bearing shaft, 7
... stator, 10 ... stator core, 10a ... positioning portion, 11 ... wires 11,30 ... positioning device body, 31
... Sphere support member, 33 ... Sphere, 37 ... Positioning member moving member (sphere moving member), 37a ... Conical outer cylindrical surface, 37b ... Inner cylindrical surface.

Claims (3)

[Claims] 1. A housing, a bearing member arranged at a predetermined position inside the housing, a rotor rotatably supported by the bearing member, and the housing around the rotor in a state of being concentric with the shaft center of the bearing member. A toroidal coil motor having an annular stator that is positioned and fixed, wherein the stator is composed of an annular stator core coated with insulation and wires wound around a plurality of circumferential positions of the stator core. (Y01) A toroidal coil motor having the requirement (Y01), (Y01) A plurality of positioning portions at three or more positions are provided on the inner surface of the annular stator core other than the portion where the wire is wound, and the positioning is performed. The part is not painted. 2. A housing, a bearing member disposed at a predetermined position inside the housing, a rotor rotatably supported by the bearing member, and a housing which is concentric with the shaft center of the bearing member around the rotor. An annular stator fixedly positioned and fixed, wherein the stator comprises an annular stator core on which insulating coating is applied except for a plurality of positioning portions on an annular inner surface, and a wire wound around a plurality of circumferential positions of the stator core. A stator positioning device used for determining a fixing position of the stator to the housing when manufacturing a toroidal coil motor including the following requirements (Y02) to (Y04): A positioning device for the stator, (Y02) a positioning device body supported at a predetermined position with respect to the shaft center of the bearing member, (Y03) A positioning member supporting member that is supported by the positioning device body and that supports a positioning member that is movable in the radial direction at positions corresponding to the plurality of positioning portions on the annular inner surface of the stator core, (Y04) The positioning member Has a conical outer cylindrical surface that can come into contact with the inner surface of the bearing member and an inner cylindrical surface that can move in the axial direction in a state of being concentric with the shaft center of the bearing member, and can move in the axial direction by the positioning device body Positioning member moving member supported. 3. The positioning device for a stator according to claim 2, wherein the following requirements (Y05) to (Y07) are satisfied: (Y05) The positioning member is formed of a sphere. (Y06) The bearing member is composed of a bearing shaft having a groove for forming a dynamic pressure air bearing on the outer peripheral surface thereof. (Y07) Movable in the axial direction in a state of being concentric with the shaft center of the bearing member. The inner cylindrical surface is constituted by an inner cylindrical surface slidably fitted to the bearing shaft.