JP2006280035A - Stepping motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stepping motor capable of attaining size reduction without causing insulation failure of an air-cored coil winding. <P>SOLUTION: This stepping motor 1 includes an annular first stator core 31 in which a plurality of pole teeth stand at an inner-periphery edge and an air-cored coil 33 around which the pole teeth are fitted, and an insulation film 50 is formed at a surface of the air-cored coil 33. Because the air-cored coil 33 is roughly annular and simple in its shape, it is possible to uniformly form the insulation film 50 on its surface. Therefore, the insulation film 50 can be formed on the whole surface of the air-cored coil 33 with the prescribed film thickness to reduce cutting or insulation failure. The insulation film is not applied to the stator core, and preferable magnetic joint of the stator core can be obtained, thus providing the motor without variations in motor characteristics. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a stepping motor. More specifically, the present invention relates to a stepping motor using an air-core coil.

In general, a stepping motor is generally composed of a rotor part having a magnet fixed to a rotating shaft, a stator part facing the rotor part, an annular coil bobbin, and a coil winding wound around a body part of the coil bobbin. It is configured.

  In order to reduce the size of such a stepping motor, for example, when the motor size is about 10 mm in diameter, a coil bobbin is integrally formed by insert molding on the inner stator core constituting the stator portion, thereby reducing the bobbin size.

  Further, when the motor size is reduced to about 5 mm in diameter, the coil bobbin occupies a large proportion when the coil bobbin is integrally formed with the stator core. For this reason, there is a problem that a required winding space cannot be secured and a necessary motor torque cannot be obtained.

  Therefore, a stepping motor has been developed in which an insulating film is formed on the surface of the stator core, coil winding is wound directly on this surface, the coil bobbin is omitted, the proportion occupied by the coil bobbin is eliminated, and the coil winding space is increased (for example, , See Patent Document 1).

JP 2004-112985 A

In a stepping motor, in order to obtain good motor characteristics, it is necessary to form a magnetic coupling with a small magnetic resistance between the stator core and the stator core. For this reason, in the stepping motor shown in Patent Document 1, when an insulating film is formed on the stator core, it is necessary to perform a masking process so that the insulating film is not formed on the coupling portion of the stator core in order to ensure good magnetic coupling. And the process becomes complicated. However, an insulating film is formed at the coupling portion due to the masking deviation, which may cause deterioration of motor characteristics due to an increase in magnetic resistance and variation in characteristics between motors.

  Furthermore, the shape of the stator core is a complicated shape with an annular shape in which a plurality of pole teeth stand at the inner peripheral edge, and there is a problem that it is difficult to form an insulating film uniformly. If the insulating film is thin, there are problems such as defective insulation due to burrs and cutting of the air-core coil winding, and if the insulating film is thick, miniaturization is hindered.

  Also, since the air-core coil is only the winding insulation film compared to the bobbin coil wound around the bobbin, the insulation film is destroyed by contact with other metal parts and assembly jigs in the motor assembly process. There is a fear. Therefore, when assembling the stator core around which the coil winding is wound, there is a problem that the work must be proceeded carefully so as not to break against other members and the processing time becomes longer.

  By insulating the stator core, the terminal portion can be formed integrally with the stator core. However, since the surfaces having the jaw portions on which the terminal pins of the two inner stator yokes are formed are closely fixed, the arrangement of the terminal pins is the rotor. The rotation axis has only a degree of freedom in the direction perpendicular to the axial direction. When the motor diameter is reduced by downsizing, the distance between the terminal pins arranged in the direction perpendicular to the axial direction of the rotor rotating shaft becomes narrower, and the workability when soldering the terminal wire for drawing the coil and the terminal pin is lowered. In addition, when soldering a plurality of terminal pins, the terminal wires may be short-circuited or disconnected due to melting of the solder of other terminal pins already soldered by the heat of soldering.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a stepping motor that is suitable for miniaturization without causing a poor insulation of a coil winding.

  In order to achieve such an object, the present invention includes an annular stator core in which a plurality of pole teeth stand up at the inner peripheral edge, and an air core coil fitted around the pole teeth. An insulating film is formed on the surface.

  According to the present invention, since the air core coil fitted around the pole teeth of the stator core has an insulating film formed on the surface thereof, the entire surface of the air core coil has a predetermined shape because of its substantially annular shape and simple shape. The insulating film can be formed with a film thickness, and the occurrence of cutting or insulation failure is reduced. In addition, since the stator core is not coated with an insulating film, the stator core can constitute a good magnetic coupling.

  Moreover, in this invention, it is preferable to have a terminal part provided separately from the said stator core, and the terminal pin of the said terminal part is arrange | positioned in the axial direction of a rotor rotating shaft.

  In this invention, since the said terminal part is provided separately from the said stator core and the terminal pins are formed with the insulator, the insulation between terminal pins can be kept favorable. In addition, since the terminal pins are arranged in the axial direction of the rotor rotation shaft, the terminal pins can be arranged while increasing the distance between the terminal pins even if the motor is downsized.

  Furthermore, in the present invention, the stator core is preferably deburred. Since the burr and sink generated by processing the stator core are removed or reduced by deburring the stator core, the burr and sink of the front data core are reduced even if the insulating film formed on the air-core coil is thinned. This eliminates the occurrence of poor insulation of the air-core coil and cutting of the winding. In addition, since the insulating film of the air-core coil can be made thin, the motor characteristics can be reduced by reducing the size of the air-core coil and the number of windings of the air-core coil can be increased. It becomes possible.

  Further, in the present invention, another stator core having an annular shape in which a plurality of pole teeth stand at the inner peripheral edge is overlapped in the axial direction with respect to the stator core, and the other stator core and the axial direction of the other stator core are overlapped. It is preferable that it is a non-contact state with the end surface of the said air-core coil which opposes an end surface.

  According to the present invention, the other stator core and the end surface of the air-core coil facing the end surface in the axial direction of the other stator core are in a non-contact state, so that it is inexpensive without interposing an insulating member. Insulation can be maintained.

  The stepping motor of the present invention includes an annular stator core in which a plurality of pole teeth stand at the inner peripheral edge, and an air core coil fitted around the pole teeth, and is insulated on the surface of the air core coil. A film is formed.

  According to the present invention, since the air core coil fitted around the pole teeth of the stator core has the insulating film formed on the surface thereof, the insulating film is formed with a predetermined film thickness on the entire surface of the air core coil. And less likely to cause cutting or insulation failure. In addition, since the stator core is not coated with an insulating film, the stator core can constitute a good magnetic coupling.

(Motor structure)
FIG. 1 is a cross-sectional view of a main part of a PM (permanent magnet) type stepping motor to which the present invention is applied.

  FIG. 2 is an explanatory view showing the structure of the stator portion 3 of the stepping motor 1 shown in FIG.

(Motor configuration)
A stepping motor 1 according to the present embodiment shown in FIG. 1 includes a rotor portion 2 having a rotating shaft 21 and a rotor magnet (permanent magnet) 22, and a stator portion 3 arranged to face the rotor magnet 22 via a gap. The rotary shaft 21 is rotatably supported by the bearing 4 and is spring-biased in the axial direction by a spring member 5 that abuts one end of the rotary shaft 21.

  The support on the other end side of the rotating shaft 21 is rotatably supported by a bearing different from the bearing 4 (not shown). This other bearing is provided, for example, in the vicinity of the outlet end opening of the first stator core 31 or the opening inside the mounting plate, or is provided at the tip of the rotating shaft 21 via a casing (not shown).

  A rotor magnet 22 is fixed to the rotating shaft 21 by adhesion on the rotating shaft 21 constituting the rotor unit 2, and the rotor magnet 22 is formed of a substantially cylindrical permanent magnet.

  Further, the rotor magnet 22 is formed with circular recesses on both end surfaces in the axial direction, and the rotor magnet 22 itself is further reduced in weight by forming these recesses. Thus, the inertia moment of the rotor magnet 22 is reduced by reducing the weight.

  The other end of the rotating shaft 21 is an output shaft extended so as to output the rotation of the stepping motor 1.

  The stator portion 3 is configured in a two-phase structure by a first stator core 31 and a second stator core 32 fixed back to back with the first stator core 31.

  The first and second stator cores 31 and 32 are configured such that a plurality of pole teeth are alternately arranged. The outer peripheral part of these pole teeth and the chrysanthemum between the pole teeth are chamfered. For this reason, the insulation defect of the air-core coils 33 and 34 due to the burr of the pole teeth can be reduced. The size of the burr is preferably set to 0.03 mm or less by the chamfering process here.

  An annular air core coil 33 is disposed on the outer periphery of each pole tooth in the first stator core 31. Similarly, an annular air core coil is disposed on the outer periphery of each pole tooth in the second stator core 32. 34 is arranged.

  An insulating film 50 that enhances insulation is formed on the entire surface of the annular air-core coils 33 and 34.

  Further, the first stator core 31 and the air-core coil 33 are fixed using an adhesive.

  Similarly, the second stator core 32 and the air-core coil 34 are fixed using an adhesive.

  Further, the air-core coils 33 and 34 are housed in spaces formed by the first stator core 31 and the first stator core 37, and the second stator core 32 and the second stator core 38, respectively. The stator core and the stator core are fitted, press-fitted, or fitted and fixed and fixed at portions other than the pole teeth, and are magnetically bonded.

  This stepping motor 1 includes stator cores 31 and 32, air-core coils (drive coils) 33 and 34 assembled to the stator cores 31 and 32, and terminals 33a of windings of the air-core coils (drive coils) 33 and 34, And a terminal block 35 provided with a plurality of terminal pins 36 around which a pin 34a is wound, and the fitting portion 35a of the terminal block 35 is fitted to the stator cores 31 and 32 as shown in FIGS. A gap 41 is provided between the terminal block 35 and the drive coils 33 and 34 while being fitted to the portions 31b and 32b.

  The fitting portion 35a of the terminal block 35 is a through hole. Further, the fitting portions 31b and 32b of the stator cores 31 and 32 are formed of protrusions that are press-fitted into the fitting portion 35a. Thereby, it is possible to easily assemble and prevent the terminal block 35 from falling. As shown in FIG. 5, the terminal pin 36 is made of a metal L-shaped pin. The terminal pin 36 is insert-molded together with an insulating material made of a liquid crystal polymer to form a terminal block 35. High heat resistance can be obtained by using a liquid crystal polymer.

  The terminal pins 36 are arranged in a square shape. Thereby, since the length of the terminal block 35 in the circumferential direction of the motor can be shortened as compared with the case where it is arranged linearly as in the prior art, the size of the motor 1 can be reduced.

  Each terminal pin 36 is provided in a direction parallel to the radial direction of the motor 1. The base portion 36 a of each terminal pin 36 is provided in the axial direction of the motor 1 and slightly protrudes from the terminal block 35. For this reason, since wiring is also possible for the base portion 36a, wiring can be made to the base portion 36a even when wiring to the terminal pins 36 is not possible due to installation space, for example. Even after the motor 1 is installed in the apparatus, the electrical characteristics of the motor 1 can be confirmed using the base 36a. Furthermore, since the terminal pin 36 is L-shaped, the strength against disconnection is extremely strong.

  A plurality of protrusions 42 are formed around the fitting portion 35 a of the terminal block 35 on the side fitted to the fitting portions 31 b and 32 b of the stator cores 31 and 32. As a result, as shown in FIG. 5A, the winding terminals 33a and 34a are prevented from coming into contact with the edge of the through hole for taking out the winding of the motor case 37, thereby preventing disconnection due to the edge. Can do. Further, the protrusion 42 is caught on the edge of the motor case 37, so that the terminal block 35 can be prevented from falling.

  Further, a step portion 43 is formed around the terminal pin 36 of the terminal block 35, and winding terminals 33 a and 34 a are wound around the terminal pin 36 along the step portion 43. Therefore, as shown in FIGS. 6 and 4, since the terminal 33a of the winding reaches the terminal pin 36 in the step portion 43, even if the FPC 44 or the like is attached later, the portion immediately before reaching the terminal pin 36 of the winding 33b does not interfere. Thereby, there is no possibility that the said part 33b will be cut | disconnected by FPC44, and the yield at the time of attaching the motor 1 can be raised.

  Further, the first stator core 31 is housed in another first stator core 37, and similarly, the second stator core 32 is housed in another second stator core 38.

  In the present embodiment, the other first stator core 37 also functions as a motor case, and will be referred to as a first motor case 37 below. Similarly, another second stator core 38 is described as a second motor case 38.

  As shown in FIG. 1, the first and second stator cores 31, 32, the first motor case 37, and the second motor case 38 are disposed concentrically with the axis of the rotary shaft 21, and are fixed by welding. ing.

  Here, the motor 1 includes a motor case 37 provided with an opening 46 as shown in FIG. 7 and a mounting plate 45 to which the motor case 37 is attached. The motor case 37 and the mounting plate 45 are fixed by spot welding or the like.

  As shown in FIG. 8, the first motor case 37 is formed in a bottom surface portion 37a having at least one straight line portion, a side surface portion 37c having a flat surface portion 37d having the straight line portion as a side, and a flat surface portion 37d. And an opening 46. And it has the rib 37b in the edge | side which faces the bottom face part 37a of the opening part 46. As shown in FIG.

  In the present embodiment, as shown in FIG. 1 and FIG. 2, the axial length X formed by the first stator core 31 and the first motor case 37 and the axial length of the air-core coil 33. The relationship with the height Y is set such that X> Y.

  A gap S is formed between the end surface of the first motor case 37 in the axial direction and the end surface of the air-core coil 33 facing the end surface in order to ensure insulation. A gap S is similarly formed in the axial direction between the second motor case 38 and the air-core coil 34.

  The bearing 4 is formed of a resin having lubricity, and supports one end of the rotating shaft 21 so as to be rotatable in the radial direction.

  The bearing 4 that supports the radial direction includes a bearing portion that supports the rotating shaft 21 to be inserted, a press-fit portion that is press-fitted and fixed to the inner diameter of the second stator core 32, and a flange portion in which a part of the outer peripheral portion projects in the radial direction Is formed.

  The bearing portion of the bearing 4 is disposed so as to enter a recess formed in the rotor magnet 22, and the axial dimension of the entire stepping motor 1 is suppressed.

  Further, the inner diameter of the bearing portion is large enough to form a clearance as compared with the outer diameter of the rotating shaft 21.

  Further, the collar portion of the bearing 4 is placed on the second stator core 32 and is positioned in the axial direction.

  The spring member 5 is formed of a single metal plate, and is provided with a spring piece that comes into contact with one end of the rotating shaft 21 and a center hole.

  The spring member 5 is welded and fixed to the second motor case 38.

  The spring piece of the spring member 5 is in contact with one end of the rotary shaft 21 and biases the rotary shaft 21 in the axial direction.

  Next, the air-core coil and the insulating sheet constituting the stator portion will be described with reference to FIG.

  In the present embodiment, the stator unit 3 is composed of two sets, but has the same structure, and therefore the first stator core 31 will be described here, and the description of the second stator core 32 will be omitted.

  The air-core coil 33 fitted to the first stator core 31 is obtained by applying an insulating film 50 to the entire surface of a coil winding that is wound a plurality of times.

  The coil winding has a thin self-bonding layer formed on the surface thereof, and heat is applied to melt the self-bonding layer so that adjacent coil windings are fixed to each other.

  In addition, the insulating film 50 formed on the entire surface of the coil winding wound a plurality of times is a paint mainly composed of polyamideimide resin in the present embodiment.

  The air core coil 33 is manufactured as follows.

  First, the coil winding is wound around a bar material serving as a winding core, the winding start end 33a and the winding end end 33a being exposed on the surface of the winding layer, so that a predetermined motor torque can be obtained. The

  Note that the bar used as the winding core has an outer diameter that is substantially the same as that of the outer periphery formed by the plurality of pole teeth formed on the first stator core 31.

  During the winding, hot air is blown from the outside during winding, and the winding is self-fused at the same time as winding, and the coil windings wound on the winding core are bonded to each other. After the fusion, the winding rod is pulled out, and the wound coil winding is formed in the air-core coil 33.

  In the self-bonding of the winding, after winding, a predetermined voltage is applied between the winding start end 33a and the winding end 33a, current is passed through the coil winding to generate heat, and the surface of the coil winding is applied. These self-bonding layers may be fused and solidified, and the coil windings wound on the core may be bonded together.

  Next, the insulating film 50 is formed on the surface of the air-core coil 33 by dipping coating.

  Briefly, in the dipping coating, the air-core coil 33 is dipped in a paint tank mainly composed of polyamideimide resin, pulled up, blown off using an air blow, and dried. The above steps are repeated until a predetermined film thickness, for example, a film thickness of about 30 μm in this embodiment is secured. The thickness of the insulating film is preferably equal to or greater than the size of burrs and sink marks of the stator core to which the air-core coil is fitted or fixed. On the other hand, if the insulating film is thickened, the coil becomes large, so that the thickness is preferably 100 μm or less.

  The insulating film forming method on the air-core coil 33 may be formed by a spray coating method such as spraying.

  Further, by fixing the air core coil 33 and the first stator core 31 with an adhesive, the air core coil 33 moves in the axial direction and contacts the end face of the first motor case 37 facing in the axial direction. Can be prevented.

  Since the first and second stator cores 31 and 32 and the first and second motor cases 37 and 38 are formed by pressing, burrs and sink marks are generated in the pressing process. That is, when there are burrs or sink marks remaining on the pole teeth or the end surface 31a of the first stator core 31, or when the air-core coil 33 is fitted, the insulating film 50 may be peeled off by the burrs or sink marks, or the burrs and sink marks. Piercing the insulating film 50 may cause a short circuit between the coil winding and the first stator core 31, or the coil winding may be disconnected or have a poor withstand voltage.

  By increasing the thickness of the insulating film 50 of the air-core coil 33, it is possible to prevent disconnection of the air-core coil 33 due to burrs and sink marks and poor insulation from the first stator core 31, but The coil 33 is enlarged, which hinders miniaturization of the motor.

  For this reason, if the burrs and sink marks are reduced by performing barrel processing of the first stator core 31 and deburring processing of the punched portion by pressing, the coil winding and the first stator core 31 may be short-circuited or the coil winding may be There is no possibility of disconnection or breakdown voltage failure.

  For this reason, the first and second stator cores 31 and 32 and the first and second motor cases are subjected to deburring processing such as barrel processing or chamfering with a press at the pole tooth portion or the like where the air-core coil 33 contacts. Are preferred.

  When assembling the stepping motor 1 described above, as shown in FIG. 2, the first stator core 31 (or the second stator core 32) from which the first motor case 37 (or the second motor case 38) has been removed has an air core. The coil 33 (or the air core coil 34) is fitted to the outer periphery of the pole teeth of the first stator core 31 (or the second stator core 32), and the air core coil 33 is bonded and fixed. Then, the terminal block 35 is press-fitted into the fitting portions 31b and 32b of the stator cores 31 and 32 and temporarily fixed. Further, the terminals 33 a and 34 a of the coils 33 and 34 are wound around the terminal pin 36.

  Next, the stator part 3 is assembled by attaching the first motor case 37 (or the second motor case 38). As shown in FIG. 1, the stator portion 3 is assembled so as to face the rotor magnet 22 with a gap therebetween. Here, the terminal block 35 is bonded to the motor cases 37 and 38 and fixed.

The assembly of the stepping motor 1 is the same as that of a conventionally known stepping motor or the like, and thus detailed description thereof is omitted here.
(Other embodiments)

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention.

  For example, in the present embodiment, the bottom surface portion 37a of the motor case 37 has an oval shape, but is not limited thereto, and may have a rectangular shape or a cylindrical shape.

Moreover, although the edge part of the base part 36a protrudes from the terminal block 35, it does not need to protrude. Further, in the present embodiment, the protrusion 42 and the stepped portion 43 are provided on the terminal portion 35, but these may be omitted and may be provided as necessary.

  In the present embodiment, the terminal pins 36 are insert-molded together with an insulating material made of a liquid crystal polymer. However, the present invention is not limited to this, and insert molding using other materials may be used. Alternatively, the terminal pin 36 may be provided on the terminal block 35 by press fitting or the like.

The terminal pins may be arranged in a substantially square shape or a substantially parallelogram shape. It is preferable that at least two or more terminal pins are arranged in the axial direction of the rotating shaft 21. By arranging the terminal pins in this way, the terminal portion 35 can be configured without protruding from the motor diameter (motor width) which is reduced in size and reduced.
Further, since at least two terminal pins are arranged in the axial direction of the rotary shaft 21, the distance between the terminal pins can be widened. Therefore, when the terminal pins and the lead terminal wires of the air-core coil are connected by soldering, the terminal pins There is no possibility that the soldering between the terminals and the already soldered terminal pins are melted by the soldering heat of the other terminal pins, resulting in poor connection. Since the terminal block 35 separates the terminal pins and the terminal pins from the stator cores 31 and 32 with an insulating resin, it is difficult for the soldering heat to be transmitted. For this reason, soldering of the soldered terminal pins, melting of the insulating film of the air-core coils 33 and 34 in contact with the stator cores 31 and 32 and the self-bonding layer of the air-core coil windings are prevented. .

(Stepping motor operation)
In the stepping motor 1 configured as described above, a predetermined current is supplied to the air-core coils 33 and 34 of the stator unit 3, thereby causing a rotor magnet to generate magnetic interaction between the stator unit 3 and the rotor magnet 22. Is urged to rotate, and the rotating shaft 21 integral therewith rotates. Since the operation of the stepping motor 1 is the same as that of a conventionally known stepping motor or the like, detailed description thereof is omitted here.

  The stepping motor 1 includes annular first and second stator cores 31 and 32 in which a plurality of pole teeth stand at the inner peripheral edge, and air-core coils 33 and 34 fitted around the pole teeth. An insulating film 50 is formed on the surfaces of the air-core coils 33 and 34.

  The air-core coil 33 has a substantially annular shape, and since the shape is simple, the insulating film 50 can be uniformly formed on the surface thereof. For this reason, the insulating film 50 can be formed with a predetermined film thickness on the entire surface of the air-core coil 33, and it is less likely to cause cutting or insulation failure.

  Since the stator core is not coated with an insulating film, a good magnetic coupling of the stator core can be formed, so that a motor without variations in motor characteristics can be supplied.

  Further, the stepping motor 1 has a terminal portion 35 provided separately from the stator cores 31 and 32, and the terminal pin 36 of the terminal portion 35 is arranged in the axial direction of the rotating shaft 21.

Thereby, since the terminal part 35 is provided separately from the stator cores 31 and 32 and the terminal pins are formed of an insulator, the insulation between the terminal pins can be maintained well. Further, since the terminal pins 36 are arranged in the axial direction of the rotating shaft 21, even if the motor is downsized, the terminal pins can be arranged with a wide distance between the terminal pins.
Further, even during operation, it is possible to prevent the air-core coil 33 from moving in the axial direction or the radial direction and coming into contact with members constituting the motor, so that cutting or insulation failure does not occur.

Further, in the stepping motor 1, the stator cores 31 and 32 and the motor cases 37 and 38 are deburred.
As a result, burrs and sink marks generated by processing the stator cores 31 and 32 and the motor cases 37 and 38 are removed or reduced, so that the insulating film 50 formed on the air-core coils 33 and 34 is formed on the stator cores 31 and 32. In addition, peeling of the motor cases 37 and 38 due to burrs and sink marks, and entry of burrs and sink marks into the insulating film 50 can be prevented. As a result, the insulation failure of the air-core coils 33 and 34, the winding cut, and the breakdown voltage failure are eliminated. Further, since the insulating film 50 of the air core coils 33 and 34 can be made thin, the motor can be downsized by reducing the size of the air core coils 33 and 34, and the number of windings of the air core coils 33 and 34 can be increased. Therefore, the motor characteristics can be improved.

  In the stepping motor 1, an annular first motor case 37 (another first stator core) in which a plurality of pole teeth stand at the inner peripheral edge is overlapped with the first stator core 31 in the axial direction. In addition, the first motor case 37 and the end surface of the air-core coil 33 facing the end surface in the axial direction of the first motor case 37 are in a non-contact state, so that it is inexpensive without interposing an insulating member. Insulation can be maintained.

It is a sectional side view showing the outline of a stepping motor. It is an exploded view showing an air core coil and an insulating sheet. It is a front view which shows the principal part of the stepping motor of this invention. It is a top view which shows the relationship between a terminal block and a stator. It is a figure which shows a terminal block, (a) is the II sectional view taken on the line in (b), (b) is a top view, (c) is the II-II sectional view in (b), (d) is a bottom face FIG. It is a side view which shows the detail of a step part. It is a figure which shows a motor, (a) is a side view, (b) is a bottom view. It is a bottom view which shows welding with a motor case and a mounting plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stepping motor 31, 32 Stator core 31b, 32b Stator core fitting part 33, 34 Driving coil 33a, 34a End of winding 35 Terminal block 35a Terminal block fitting part 36 Terminal pin 41 Gap 42 Projection 43 Step part

Claims (4)

An annular stator core in which a plurality of pole teeth stand at the inner periphery, and an air-core coil fitted around the pole teeth;
A stepping motor, wherein an insulating film is formed on a surface of the air-core coil. A terminal portion provided separately from the stator core;
2. The stepping motor according to claim 1, wherein the terminal pins of the terminal portion are arranged in the axial direction of the rotor rotation shaft. The stepping motor according to claim 1, wherein the stator core is chamfered. Another stator core having an annular shape in which a plurality of pole teeth stand at the inner peripheral edge is overlapped in the axial direction with respect to the stator core, and the other stator core and the end surface in the axial direction of the other stator core are opposed to each other. 4. The stepping motor according to claim 1, wherein the stepping motor is in a non-contact state with an end face of the air-core coil.

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