JP7278162B2 - stepper motor - Google Patents

Description

The present invention relates to a stepping motor in which an A-phase stator pair and a B-phase stator pair are arranged in the axial direction of the motor.

A stepping motor includes a rotor having permanent magnets fixed to the outer peripheral surface of a rotating shaft, and a stator arranged to face the outer peripheral surface of the permanent magnets. The stators are arranged such that the A-phase stator pair and the B-phase stator pair are adjacent to each other in the axial direction of the motor. On the other hand, as a structure that can secure a large torque even when the diameter of the stepping motor is reduced, a structure has been proposed in which a plurality of stators each having an A-phase stator set and a B-phase stator set are arranged in the motor axis direction ( See Patent Document 1). In Patent Document 1, a cylindrical case is arranged around a plurality of stators having an A-phase stator set and a B-phase stator set to hold the stator.

JP-A-2000-152593

However, in the configuration described in Patent Document 1, since the case is arranged around the stator, there is a problem that the thickness of the case impairs the reduction in diameter of the motor. On the other hand, if the case is omitted from the configuration described in Patent Document 1, it becomes difficult to assemble the motor while ensuring the coaxiality of the stator assembly.

In view of the above problems, an object of the present invention is to ensure the coaxiality of each stator pair even when increasing the number of A-phase and B-phase stator pairs to secure a large torque in order to reduce the diameter of the stator. To provide an easy stepping motor.

In order to solve the above problems, a stepping motor according to the present invention includes a rotor provided with permanent magnets on the outer peripheral side of a rotating shaft extending in the axial direction of the motor, and the permanent magnets are disposed so as to face the permanent magnets radially outward. a cylindrical stator portion, wherein the stator portion has a plurality of stators stacked in the axial direction of the motor, and each of the plurality of stators has an A-phase coil wound thereon; A phase coil bobbin, a phase A first core that overlaps the A phase coil bobbin from one side in the motor axial direction, and a phase A second core that overlaps the A phase coil bobbin from the other side in the motor axial direction. a B-phase coil bobbin around which a B-phase coil is wound; a B-phase first core overlapping the B-phase coil bobbin from the other side; a B-phase second core overlapping from the other side of the A-phase stator assembly, and a B-phase stator assembly overlapping from the other side of the A-phase stator assembly, and in each of the plurality of stators, the A-phase first core and the B-phase first core are fixed, and the B-phase first core and the A-phase first core, which overlap at the boundary between the plurality of stators, are fixed.

In the present invention, since a plurality of stators having the A-phase stator group and the B-phase stator group are arranged in the axial direction of the motor, a large torque can be obtained even when the diameter of the motor is reduced. In each of the plurality of stators, the A-phase first core and the B-phase first core located on both sides in the motor axial direction are fixed, and the B-phase first core and the A-phase first core overlap at the boundary portion of the plurality of stators. Since the first phase core is fixed, coaxiality of the stator assembly can be easily ensured during assembly without housing the stator assembly in a separate case. Therefore, it is easy to reduce the diameter of the motor.

In the present invention, the A-phase first core includes an A-phase annular plate portion that overlaps the A-phase coil bobbin from one side, and is bent from an outer edge of the A-phase annular plate portion toward the other side. a cylindrical A-phase case portion, wherein the B-phase first core includes a B-phase annular plate portion overlapping the B-phase coil bobbin from the other side; and an outer edge of the B-phase annular plate portion. and a cylindrical B-phase case portion bent toward the one side from the B-phase first core and the A-phase first core overlapping at the boundary portion of the plurality of stators by welding. The first welding marks when fixed are formed on the outer surface of the bent portion between the B-phase annular plate portion and the B-phase case portion, and the A-phase annular plate portion and the A-phase case portion. It is possible to adopt a mode in which it exists so as to straddle both of the outer surfaces of the bent portion between. According to this aspect, the A-phase first core and the B-phase first core can be fixed by welding at any stage during assembly.

In the present invention, the radial outer surface of the bent portion between the A-phase annular plate portion and the A-phase case portion, and the radially outer surface between the B-phase annular plate portion and the B-phase case portion It is possible to employ a mode in which both radially outer surfaces of the bent portion are convexly curved surfaces that are convexly curved radially outward. According to this aspect, when the A-phase case portion is bent from the outer edge of the A-phase annular plate portion by drawing, and when the B-phase case portion is bent from the outer edge of the B-phase annular plate portion by drawing. , the radially outer surface of the bent portion becomes a convex curved surface. Therefore, when the A-phase case is bent from the outer edge of the A-phase annular plate portion and when the B-phase case portion is bent from the outer edge of the B-phase annular plate portion, a special curved surface is not generated. No additional bending or additional post-processing is required.

In the present invention, it is possible to employ an aspect in which the first weld marks are present at a plurality of locations spaced apart in the circumferential direction. According to this aspect, since it is not necessary to weld the entire circumference, work efficiency can be improved.

In the present invention, in each of the plurality of stators, the A-phase case portion extends to a position covering the A-phase second core from the radially outer side, and the B-phase case portion extends to the B-phase and extends to a position covering the second core for the phase A from the outside in the radial direction, and the second weld mark when the first core for the A phase and the first core for the B phase are fixed by welding forms the second weld mark for the phase A Straddling the radially outer surface of the tip portion of the case portion on the side of the second core for phase A and the radially outer surface of the tip portion of the case portion for phase B on the side of the second core for phase B Existing aspects can be adopted. According to this aspect, in each of the plurality of stators, the A-phase first core and the B-phase first core can be easily fixed. Further, since the case can be configured using the A-phase case portion integrated with the first A-phase core and the A-phase case portion integrated with the first B-phase core, the stator portion can be Intrusion of foreign matter can be prevented. Furthermore, since the case portion is provided for each of the A-phase stator set and the B-phase stator set, the length of the case portion is short. Therefore, even if the plate material forming the core is made thinner as the diameter of the stepping motor is reduced, the case portion can be easily formed by drawing.

In the present invention, it is possible to employ an aspect in which the second weld marks are present at a plurality of locations spaced apart in the circumferential direction. According to this aspect, since it is not necessary to weld the entire circumference, work efficiency can be improved.

In the present invention, in each of the plurality of stators, the A-phase case portion is formed with an A-phase opening extending in the motor axis direction, and the B-phase case portion is formed with the motor axis line. a B-phase opening forming an opening connected to the A-phase opening by extending in the direction of the A-phase terminal block formed integrally with the A-phase coil bobbin from the opening; , and a B-phase terminal block formed integrally with the B-phase coil bobbin protrudes radially outward. According to this aspect, even when the diameter of the stepping motor is reduced, the A-phase terminal block and the B-phase terminal block can be projected radially outward.

In the present invention, in each of the plurality of stators, the A-phase opening extends throughout the A-phase case portion in the axial direction of the motor, and the B-phase opening extends over the B-phase It is possible to employ a mode in which the case portion extends over the entirety of the motor axial direction. According to this aspect, even when the size and diameter of the stepping motor are reduced, the A-phase terminal block and the B-phase terminal block can be easily protruded radially outward.

In the present invention, an aspect may be adopted in which the plurality of stators have an outer diameter of 6 mm or less.

In the present invention, it is possible to employ an aspect in which the stator section has two stators as the plurality of stators.

In the present invention, since a plurality of stators having the A-phase stator group and the B-phase stator group are arranged in the axial direction of the motor, a large torque can be obtained even when the diameter of the motor is reduced. In each of the plurality of stators, the A-phase first core and the B-phase first core located on both sides in the motor axial direction are fixed, and the B-phase first core and the A-phase first core overlap at the boundary portion of the plurality of stators. Since the first phase core is fixed, coaxiality of the stator assembly can be easily ensured during assembly without housing the stator assembly in a separate case. Therefore, it is easy to reduce the diameter of the motor.

1 is a perspective view of a stepping motor according to the present invention; FIG. FIG. 2 is a perspective view of the stepping motor shown in FIG. 1 when viewed from another direction; FIG. 2 is a cross-sectional view of the stepping motor shown in FIG. 1; FIG. 2 is an exploded perspective view when the rotor and stator shown in FIG. 1 are separated; FIG. 5 is an exploded perspective view of the stator portion shown in FIG. 4; FIG. 2 is an explanatory diagram of a B-phase first core and an A-phase first core that overlap at the boundary shown in FIG. 1 ;

A stepping motor 1 to which the present invention is applied will be described below with reference to the drawings. In the following description, when the direction along the central axis (motor axis) of the rotating shaft 21 is defined as the "motor axial direction L", in the motor axial direction L, "one side of the motor axial direction L" rotates from the stator portion 3. On the side where the shaft 21 protrudes (output side La), the "other side in the motor axial direction L" is the opposite side to the side where the rotating shaft 21 protrudes from the stator portion 3 (output side La). The description will focus on the case of the side Lb. Further, in the following description, the radial direction and the circumferential direction about the center axis (motor axis) of the rotating shaft 21 are simply referred to as "radial direction" and "circumferential direction".

(Overall Configuration of Stepping Motor 1)
FIG. 1 is a perspective view of a stepping motor 1 according to the invention. FIG. 2 is a perspective view when the stepping motor 1 shown in FIG. 1 is viewed from another direction. FIG. 3 is a cross-sectional view of the stepping motor 1 shown in FIG. FIG. 4 is an exploded perspective view when the rotor 2 and stator 30 shown in FIG. 1 are separated.

As shown in FIGS. 1, 2, and 3, the stepping motor 1 of this embodiment includes a rotor 2 provided with a cylindrical permanent magnet 22 on the outer peripheral side of a rotary shaft 21 extending in the motor axial direction L, and a permanent magnet 22. A cylindrical stator portion 3 arranged to face the magnet 22 radially outward is provided. The rotating shaft 21 is made of metal material such as stainless steel, brass, and aluminum. The permanent magnet 22 is a bonded magnet using rare earth magnetic powder, and has N poles and S poles alternately arranged in the circumferential direction.

A first end plate 70 is fixed to the end portion of the output side La of the stator portion 3 by welding or the like, and a first bearing 75 that rotatably supports the rotating shaft 21 is held in the first end plate 70 . . The first bearing 75 has a cylindrical portion 751 and a large-diameter portion 752 having a larger diameter on the output side La than the cylindrical portion 751. The cylindrical portion 751 passes through the through hole 71 of the first end plate 70. , the large-diameter portion 752 is in contact with the surface of the first end plate 70 on the output side La. In this state, the first bearing 75 is fixed to the first end plate 70 by caulking or the like to the end of the cylinder portion 751 on the counter-output side Lb. In this embodiment, a washer 90 is mounted on the rotating shaft 21 between the permanent magnet 22 and the first bearing 75 . Therefore, even when the rotor 2 moves to the output side La, the first bearing 75 and the permanent magnet 22 do not come into contact with each other.

A second end plate 80 is fixed to the end of the stator portion 3 opposite to the output side Lb, and the second end plate 80 holds a second bearing 85 that rotatably supports the rotating shaft 21 . The second bearing 85 has a cylindrical portion 851 and a large-diameter portion 852 having a larger diameter on the output side La than the cylindrical portion 851. The cylindrical portion 851 passes through the through hole 81 of the second end plate 80. , the large-diameter portion 852 is in contact with the surface of the second end plate 80 on the output side La. In this state, the second bearing 85 is fixed to the second end plate 80 by caulking or the like to the end of the tube portion 851 on the counter-output side Lb. Here, the outer peripheral portion of the large-diameter portion 852 of the second bearing 85 contacts the inner side of the root portion of the B-phase pole tooth 612B, which will be described later, so that the second bearing 85 is radially positioned. Therefore, the second bearing 85 is properly positioned in the radial direction with reference to the root portion of the B-phase pole tooth 612B. A concave portion is formed around the through hole 81 on the surface of the second end plate 80 on the non-output side Lb, and the end of the cylindrical portion 851 on the non-output side Lb protrudes from the second end plate 80 to the non-output side Lb. You may adopt the aspect which suppresses this.

The stator portion 3 has a plurality of stators 30 that are stacked in the motor axial direction L. As shown in FIG. In this embodiment, the stator portion 3 is thinned to have an outer diameter of 6 mm or less. Therefore, all of the plurality of stators 30 have an outer diameter of 6 mm or less. Therefore, in the rotor 2, the outer diameter of the rotating shaft 21 is 1 mm or less. The length of the stator portion 3 in the motor axial direction L exceeds 10 mm.

In this embodiment, the stator section 3 has two stators as the plurality of stators 30 . Therefore, in the following description, of the two stators 30, the stator 30 on the counter-output side Lb in the motor axial direction L is defined as the first stator 31, and the first stator 31 overlaps the output side La in the motor axial direction L. The stator 30 is assumed to be a second stator 32 .

As shown in FIGS. 3 and 4 , in the rotor 2 , the permanent magnets 22 are arranged so as to face each of the plurality of stators 30 radially outward. In this embodiment, the permanent magnets 22 are composed of a plurality of magnets 220 fixed to the rotating shaft 21 so as to face each of the plurality of stators 30 . More specifically, the permanent magnets 22 are composed of first magnets 221 facing the first stator 31 and second magnets 222 facing the second stator 32 . Therefore, magnets that are easy to manufacture and are inexpensive can be used as compared with the case of using magnets that extend long in the motor axial direction L.

Here, in each of the plurality of magnets 220, concave portions 226 and 227 are formed in the end surface of the anti-output side Lb and the end surface of the output side La, and the magnet 220 and the rotating shaft 21 are fixed to the concave portion 227. Adhesive 29 is provided.

(Configuration of stator 30)
5 is an exploded perspective view of the stator portion 3 shown in FIG. 4. FIG. As shown in FIGS. 1, 2, 3, and 4, in the stepping motor 1 of this embodiment, the plurality of stators 30 have the same configuration such as shape and size. Therefore, the first stator 31 and the second stator 32 have the same configuration. Therefore, when describing the stator 30 , the first stator 31 and the second stator 32 are simply described as the stator 30 when there is no need to distinguish between the first stator 31 and the second stator 32 .

Each of the plurality of stators 30 has an A-phase stator set 30A and a B-phase stator set 30B overlapping the A-phase stator set 30A from the counter-output side Lb. A stator group 30A for B-phase and a stator group 30B for B-phase are alternately arranged. In each of the plurality of stators 30, the A-phase stator group 30A and the B-phase stator group 30B have the same basic structure. They are arranged in opposite directions in the axial direction L.

More specifically, as shown in FIGS. 3, 4, and 5, the A-phase stator assembly 30A includes an A-phase coil bobbin 50A around which the A-phase coil 40A is wound, and an A-phase coil bobbin 50A. It has an A-phase first core 61A that overlaps from the output side La, and an A-phase second core 62A that overlaps the A-phase coil bobbin 50A from the counter-output side Lb. The A-phase coil bobbin 50A includes a cylindrical body portion 53A, a flange portion 51A whose diameter is enlarged at the end of the body portion 53A on the output side La, and a flange portion whose diameter is increased at the end of the body portion 53A on the counter-output side Lb. The A-phase coil 40A is wound around the trunk portion 53A between the flange portions 51A and 52A.

In this embodiment, the A-phase first core 61A includes an annular plate portion 611A (A-phase annular plate portion) overlapping the flange portion 51A of the A-phase coil bobbin 50A, and a plurality of portions in the circumferential direction of the inner edge of the annular plate portion 611A. It has an A-phase pole tooth 612A bent toward the counter-output side Lb and an A-phase case portion 613A bent from the outer edge of the annular plate portion 611A to the counter-output side Lb. The second A-phase core 62A includes an annular plate portion 621A that overlaps the flange portion 52A of the A-phase coil bobbin 50A, and A-phase pole teeth that are bent toward the output side La from a plurality of locations in the circumferential direction of the inner edge of the annular plate portion 621A. 622A, and no case portion is provided. When the A-phase first core 61A and the A-phase second core 62A thus configured are stacked on the A-phase coil bobbin 50A, the A-phase of the A-phase first core 61A is formed along the inner peripheral surface of the body portion 53A. The phase pole teeth 612A and the A-phase pole teeth 622A of the A-phase second core 62A are alternately arranged in the circumferential direction.

The B-phase stator set 30B includes a B-phase coil bobbin 50B around which a B-phase coil 40B is wound, a B-phase first core 61B overlapping the B-phase coil bobbin 50B from the counter-output side Lb, and a B-phase coil bobbin. 50B is provided with a B-phase second core 62B overlapping from the output side La. The B-phase coil bobbin 50B includes a cylindrical body portion 53B, a flange portion 51B whose diameter is enlarged at the end of the body portion 53B on the counter-output side Lb, and a flange portion whose diameter is enlarged at the end portion of the body portion 53B on the output side La. The B-phase coil 40B is wound around the trunk portion 53B between the flange portions 51B and 52B.

In this embodiment, the B-phase first core 61B includes an annular plate portion 611B (B-phase annular plate portion) that overlaps the flange portion 51B of the B-phase coil bobbin 50B, and a plurality of locations in the circumferential direction of the inner edge of the annular plate portion 611B. It has a B-phase pole tooth 612B bent toward the output side La, and a B-phase case portion 613B bent toward the output side La from the outer edge of the annular plate portion 611B. The second B-phase core 62B includes an annular plate portion 621B that overlaps the flange portion 52B of the B-phase coil bobbin 50B, and a B-phase pole that is bent toward the counter-output side Lb from a plurality of locations in the circumferential direction of the inner edge of the annular plate portion 621B. teeth 622B, and no case portion is provided. When the B-phase first core 61B and the B-phase second core 62B configured in this way are stacked on the B-phase coil bobbin 50B, the B-phase of the B-phase first core 61B is formed along the inner peripheral surface of the body portion 53B. The phase pole teeth 612B and the B-phase pole teeth 622B of the B-phase second core 62B are alternately arranged in the circumferential direction.

In this embodiment, when the stepping motor 1 is assembled so that the A-phase stator group 30A and the B-phase stator group 30B overlap in the motor axis direction L, an A-phase opening 614A and a B-phase opening 614B, which will be described later, are formed. to adjust the angular position about the motor axis. As a result, in each of the plurality of stators 30, the positions of the A-phase pole teeth 612A, 622A and the B-phase pole teeth 612B, 622B are shifted by an angle corresponding to a predetermined electrical angle. Therefore, when the stepping motor 1 is driven, the A-phase coil 40A and the B-phase coil 40B are supplied with drive signals whose phases are shifted by an angle corresponding to a predetermined electrical angle. Therefore, the accuracy of the stop position of the rotor 2 can be improved.

Further, when the stepping motor 1 is assembled so that the A-phase stator group 30A and the B-phase stator group 30B overlap in the motor axial direction L, each of the plurality of stators 30 has the A-phase case portion 613A for the A-phase. The tip portion 615A on the second core 62A side and the tip portion 615B of the B-phase case portion 613B on the side of the second B-phase core 62B are in contact with each other in the motor axial direction L.

When a plurality of stators 30 are stacked in the motor axial direction L, the B-phase first core 61B and the A-phase first core 61A overlap at the boundary portion 35 of the stator 30 . More specifically, when the first stator 31 and the second stator 32 are overlapped in the motor axial direction L, at the boundary 35 between the first stator 31 and the second stator 32, the first stator 31 for the A phase The one core 61A and the B-phase first core 61B of the second stator 32 overlap each other.

(Structure of opening 614, terminal blocks 55A, 55B, etc.)
In each of the plurality of stators 30, an A-phase terminal block 55A is provided at the outer peripheral end of one of the two flange portions 51A and 52A of the A-phase coil bobbin 50A, and the B-phase coil bobbin 50B is provided with an A-phase terminal block 55A. A B-phase terminal block 55B is provided at the outer peripheral end of one of the two flange portions 51B and 52B. A phase A terminal pin 56A made of resin is formed on the A phase terminal block 55A so as to protrude radially outward. When forming the A-phase coil 40A by winding the coil wire around the A-phase coil bobbin 50A, the end of the coil wire is wound around the A-phase terminal pin 56A and then soldered to form a terminal. be. A B-phase terminal pin 56B made of resin is formed on the B-phase terminal block 55B so as to protrude radially outward. When forming the B-phase coil 40B by winding the coil wire around the B-phase coil bobbin 50B, the end of the coil wire is wound around the B-phase terminal pin 56B and then soldered to form a terminal. be.

On the other hand, the A-phase case portion 613A is formed with an A-phase opening 614A that is a notch extending from the tip portion 615A toward the output side La, and the B-phase case portion 613B is formed with the tip portion 615B. A B-phase opening 614B is formed as a notch extending from the side toward the counter-output side Lb. Therefore, the A-phase terminal block 55A and the B-phase terminal block 55B can be projected radially outward from the A-phase opening 614A and the B-phase opening 614B.

Here, the A-phase opening 614A extends over the entire A-phase case portion 613A in the motor axis direction L, and the B-phase opening 614B extends over the entire B-phase case portion 613B in the motor axis direction L. extends across. Therefore, as a result of reducing the diameter of the stator portion 3, although the circumferential dimensions of the A-phase opening 614A and the B-phase opening 614B are short, the A-phase opening 614A and the B-phase opening 614B has a large open area. Therefore, even when the diameter of the stepping motor 1 is reduced, the A-phase terminal block 55A and the B-phase terminal block 55B can be protruded radially outward from the opening 614 with sufficient margin.

Further, in each of the plurality of stators 30, the A-phase opening 614A and the B-phase case 613B are formed at the same angular position about the motor axis. Therefore, when the A-phase stator set 30A and the B-phase stator set 30B are stacked in the motor axial direction L to form the stator 30, each of the plurality of stators 30 has the A-phase opening 614A and the B-phase case portion. 613B are connected in the motor axial direction L to form one opening 614 . Therefore, even when the diameter of the stepping motor 1 is reduced, the A-phase terminal block 55A and the B-phase terminal block 55B can be protruded radially outward from the opening 614 with sufficient margin.

Furthermore, in any one of the plurality of stators 30, openings 614 (A-phase opening 614A and B-phase case 613B) are formed at the same angular position about the motor axis. Therefore, when a plurality of stators 30 are stacked in the motor axial direction L to form the stator portion 3, the openings 614 (A-phase opening 614A and B-phase case portion 613B) formed in each of the plurality of stators 30 are , form one opening extending continuously over the entirety of the stator portion 3 in the motor axial direction L. As shown in FIG. Therefore, even when the diameter of the stepping motor 1 is reduced, the two A-phase terminal blocks 55A and the two B-phase terminal blocks 55B can be protruded radially outward from the opening 614 with sufficient margin. can.

In this embodiment, the A-phase terminal block 55A is provided on the flange portion 52A on the non-output side Lb of the A-phase coil bobbin 50A, and the B-phase terminal block 55B is provided on the flange portion on the non-output side Lb of the B-phase coil bobbin 50B. 51B. Therefore, the A-phase terminal block 55A and the B-phase terminal block 55B are arranged with sufficient spacing in the motor axial direction L from each other.

As shown in FIG. 5, the annular plate portion 621A of the A-phase second core 62A is formed with a projecting portion 628A projecting radially outward, and the annular plate portion 621B of the B-phase second core 62B is formed with a A projecting portion 628B projecting radially outward is formed. On the other hand, as shown in FIG. 2, a notch 618A is formed in the tip portion 615A of the A-phase case portion 613A on the side opposite to the A-phase opening portion 614A, and a notch 618A is formed in the tip portion 615B of the B-phase case portion 613B. , a notch 618B is formed on the side opposite to the B-phase opening 614B. Therefore, the protruding portion 628A of the A-phase second core 62A and the protruding portion 628B of the B-phase second core 62B overlap in the motor axial direction L and are exposed from the cutouts 618A and 618B.

(Fixation structure at boundary 35 of stator 30)
FIG. 6 is an explanatory diagram of the B-phase first core 61B and the A-phase first core 61A that overlap at the boundary portion 35 shown in FIG.

In the stepping motor 1 of this embodiment, the B-phase first core 61B and the A-phase first core 61A that overlap each other at the boundary portion 35 of the plurality of stators 30 are fixed. More specifically, as shown in FIG. 6, the B-phase first core 61B of the second stator 32 and the A-phase first core 61A of the first stator 31 overlap at the boundary 35 of the plurality of stators 30. It is fixed by welding. In the present embodiment, the B-phase first core 61B and the A-phase first core 61A overlapping at the boundary portion 35 of the plurality of stators 30 are located at the bent portion between the annular plate portion 611B and the B-phase case portion 613B. It is fixed by welding between the outer surface of 616B and the outer surface of the bent portion 616A between the annular plate portion 611A and the A-phase case portion 613A. Therefore, the first welding marks 66 when the B-phase first core 61B and the A-phase first core 61A that overlap at the boundary portion 35 of the plurality of stators are fixed by welding are formed on the outer surface of the bent portion 616B. and the outer surface of the bent portion 616A.

Therefore, in the state of the A-phase first core 61A and the B-phase first core 61B before the A-phase stator group 30A and the B-phase stator group 30B are assembled, the first A-phase core 61A and the first A-phase core 61A In addition to being able to fix the B-phase first core 61B by welding, the A-phase first core 61A and the B-phase first core 61A can be fixed even after the A-phase stator group 30A and the B-phase stator group 30B are assembled. The core 61B can be fixed at the boundary portion 35 by welding.

Here, in the process of manufacturing the A-phase first core 61A and the B-phase first core 61B, the magnetic plate divided into a predetermined shape is subjected to drawing processing or the like using a mold to form the A-phase pole teeth 612A. , A-phase case portion 613A, B-phase pole tooth 612B, and B-phase case portion 613B are processed so as to stand up from the annular plate portions 611A and 611B. As a result, both the radially outer surface of the bent portion 616A and the radially outer surface of the bent portion 616B become convex curved surfaces that are convex radially outward. Even in such a case, in this embodiment, the laser beam is irradiated toward the portion where the B-phase first core 61B and the A-phase first core 61A are in contact between the bent portion 616A and the bent portion 616B, The B-phase first core 61B and the A-phase first core 61A are fixed by laser welding. At this time, since laser welding is performed at a plurality of locations in the circumferential direction, the first welding marks 66 are present at a plurality of locations spaced apart in the circumferential direction. Therefore, working efficiency can be improved as compared with the case of welding the whole circumference.

As described above, in this embodiment, since welding is performed at the portions where the bent portions 616A and 616B formed of convex curved surfaces are in contact, when the A-phase case portion 613A is bent from the outer edge of the annular plate portion 611A and the outer edge of the annular plate portion 611B When the B-phase case portion 613B is bent from the bottom, it is not necessary to perform a special bending process that does not generate a convex curved surface or an additional post-processing.

Here, in the process of manufacturing the A-phase first core 61A and the B-phase first core 61B, the plate thickness of the A-phase pole tooth 612A and the B-phase pole tooth 612B is reduced by using a thinning process or the like. The plate thickness of the A-phase case portion 613A and the B-phase case portion 613B can be thinner than the plate thickness of the A-phase pole tooth 612A and the B-phase pole tooth 612B. preferable. In such a configuration, the difference between the plate thickness of the A-phase pole tooth 612A and the B-phase pole tooth 612B and the plate thickness of the annular plate portions 611A and 611B is greater than the wire diameter of the coil wire, and the A-phase case portions 613A and B If the difference between the plate thickness of the phase case portion 613B and the plate thickness of the A-phase pole teeth 612A and B-phase pole teeth 612B is greater than the wire diameter of the coil wire, a large space for winding the coil wire should be secured. can be done. Therefore, since the number of turns of the coil wire can be increased, the torque can be increased. For example, in this embodiment, the plate thickness of the annular plate portions 611A and 611B is 0.35 mm, the plate thickness of the A-phase pole tooth 612A and the B-phase pole tooth 612B is 0.23 mm, and the A-phase case portion The plate thickness of 613A and B-phase case portion 613B is 0.20 mm, and the wire diameter of the coil wire is 0.055 mm.

(fixing structure in stator 30, etc.)
In this embodiment, in each of the plurality of stators 30, the A-phase first core 61A and the B-phase first core 61B are fixed. More specifically, in each of the plurality of stators 30, the A-phase first core 61A and the B-phase first core 61B are fixed by welding. In this embodiment, since the tip portion 615A of the A-phase case portion 613A and the tip portion 615B of the B-phase case portion 613B are in contact with each other in the motor axial direction L, the tip portion 615A of the A-phase case portion 613A The front end portion 615B of the B-phase case portion 613B is fixed by laser welding. Therefore, in each of the plurality of stators 30, the second welding mark 67 when the A-phase first core 61A and the B-phase first core 61B are fixed by laser welding is the tip of the A-phase case portion 613A. It exists so as to straddle the radially outer surface of the portion 615A and the radially outer surface of the tip portion 615B of the B-phase case portion 613B. Here, the second weld marks 67 are present at a plurality of locations spaced apart in the circumferential direction. Therefore, working efficiency can be improved as compared with the case of welding the whole circumference.

Furthermore, in the present embodiment, the protruding portion 628A of the second A-phase core 62A and the protruding portion 628B of the second B-phase core 62B overlap each other in the motor axial direction L so that the A-phase case portions 613A and B-phase case portions 613A and B It is exposed from the notches 618A and 618B of the phase case portion 613B. Therefore, the projecting portion 628A of the second A-phase core 62A and the A-phase case portion 613A can be fixed by laser welding, and the projecting portion 628B of the second B-phase core 62B and the B-phase case portion 613B can be fixed together. can be fixed by laser welding.

Note that the protruding portion 628A of the A-phase second core 62A and the protruding portion 628B of the B-phase second core 62B are the same as the A-phase second core 628A before the A-phase stator group 30A and the B-phase stator group 30B are assembled. In addition to being able to fix the core 62A and the second B-phase core 62B in the state by laser welding, even after the A-phase stator group 30A and the B-phase stator group 30B are assembled, the projections 628A and 628B can be laser-welded. can be fixed by

(Main effects of this form)
As described above, in the stepping motor 1 of the present embodiment, a plurality of stators 30 each including the A-phase stator set 30A and the B-phase stator set 30B are arranged in the axial direction L of the motor. Large torque can be obtained even when the diameter is increased. In each of the plurality of stators 30, the A-phase first core 61A and the B-phase first core 61B located on both sides in the motor axial direction L are fixed, and the B-phase overlapping at the boundary portion 35 of the plurality of stators 30 is fixed. Since the first core 61B for phase A and the first core 61A for A phase are fixed, the coaxiality of the stator set can be easily ensured during assembly without housing the stator set in a separate case. Therefore, it is easy to reduce the diameter of the motor.

[Other embodiments]
In the above embodiment, the A-phase terminal block 55A is provided on the flange portion 52A on the non-output side Lb of the A-phase coil bobbin 50A, and the B-phase terminal block 55B is provided on the flange portion on the non-output side Lb of the B-phase coil bobbin 50B. 51B, the A-phase terminal block 55A is provided on the flange portion 51A on the output side La of the A-phase coil bobbin 50A, and the B-phase terminal block 55B is provided on the flange portion 52B on the output side La of the B-phase coil bobbin 50B. may be provided.

In addition, the A-phase terminal block 55A is provided on the flange portion 52A on the non-output side Lb of the A-phase coil bobbin 50A, and the B-phase terminal block 55B is provided on the flange portion 52B on the output side La of the B-phase coil bobbin 50B. Alternatively, the A-phase terminal block 55A is provided on the flange portion 51A on the output side La of the A-phase coil bobbin 50A, and the B-phase terminal block 55B is provided on the flange portion 51B on the counter-output side Lb of the B-phase coil bobbin 50B. may be

Further, when the A-phase terminal block 55A is provided on the flange portion 52A on the non-output side Lb of the A-phase coil bobbin 50A, and the B-phase terminal block 55B is provided on the flange portion 52B on the output side La of the B-phase coil bobbin 50B. , the A-phase terminal block 55A and the B-phase terminal block 55B overlap in the motor axial direction L. In this case, the A-phase terminal pin 56A and the B-phase terminal pin 56B are provided at the same angular position around the motor axis, or the A-phase terminal pin 56A and the B-phase terminal pin 56B are arranged at the same angular position. It may be provided at different angular positions about the motor axis.

Further, when the A-phase terminal block 55A is provided on the flange portion 52A on the non-output side Lb of the A-phase coil bobbin 50A, and the B-phase terminal block 55B is provided on the flange portion 52B on the output side La of the B-phase coil bobbin 50B. A portion of the A-phase terminal block 55A provided with the A-phase terminal pins 56A and a portion of the B-phase terminal block 55B provided with the B-phase terminal pins 56B may be adjacent in the circumferential direction. .

Alternatively, the A-phase terminal block 55A and the B-phase terminal block 55B may be provided at different angular positions about the motor axis.

In the above embodiment, the A-phase opening 614A extends over the entire A-phase case portion 613A in the motor axial direction L, and the B-phase opening 614B extends over the entire B-phase case portion 613B in the motor axial direction L. However, the A-phase opening 614A extends to the middle of the A-phase case 613A in the motor axis direction L, and the B-phase opening 614B extends to the motor axis of the B-phase case 613B. A mode in which it extends to an intermediate position in the direction L may be used.

In the above embodiment, in fixing the A-phase first core 61A and the B-phase first core 61B in each of the plurality of stators 30, the A-phase case portions 613A and B of the A-phase first core 61A are fixed. The first phase core 61B and the B-phase case portion 613B are fixed by welding, but only one of the A-phase first core 61A and the B-phase first core 61B is provided with a case portion. The A-phase first core 61A and the B-phase first core 61B may be fixed by welding.

In the above embodiment, the permanent magnet 22 of the rotor 2 is composed of a plurality of magnets 220, but the permanent magnet 22 may be composed of a single magnet.

DESCRIPTION OF SYMBOLS 1... Stepping motor 2... Rotor 3... Stator part 30... Stator 21... Rotating shaft 22... Permanent magnet 30A... A-phase stator group 30B... B-phase stator group 31... First stator, 32 Second stator 35 Boundary portion 40A Phase A coil 40B Phase B coil 50A Phase A coil bobbin 50B Phase B coil bobbin 51A, 51B, 52A, 52B Flange portion 55A... Terminal block for A phase, 55B... Terminal block for B phase, 56A... Terminal pin for A phase, 56B... Terminal pin for B phase, 61A... First core for A phase, 61B... First core for B phase, 62A...Second core for A phase 62B...Second core for B phase 66...First welding mark 67...Second welding mark 220...Magnet 221...First magnet 222...Second magnet 611A... Annular plate portion (A-phase annular plate portion) 611B... Annular plate portion (B-phase annular plate portion) 621A, 621B... Annular plate portion 612A, 622A... A-phase pole tooth 612B, 622B... B-phase 613A...A phase case portion 613B...B phase case portion 614...Opening portion 614A...A phase opening portion 614B...B phase opening portion 615A, 615B...End portion 616A, L... motor axial direction, La... output side, Lb... anti-output side

Claims (10)

a rotor provided with a permanent magnet on the outer peripheral side of a rotating shaft extending in the axial direction of the motor;
a cylindrical stator portion disposed so as to face the permanent magnet radially outward;
has
The stator section has a plurality of stators stacked in the axial direction of the motor,
each of the plurality of stators,
An A-phase coil bobbin around which an A-phase coil is wound, an A-phase first core overlapping the A-phase coil bobbin from one side in the motor axial direction, and an A-phase coil bobbin on the other side in the motor axial direction. an A-phase stator set including an A-phase second core that overlaps with another;
A B-phase coil bobbin around which a B-phase coil is wound, a B-phase first core overlapping the B-phase coil bobbin from the other side, and a B-phase second core overlapping the B-phase coil bobbin from the one side a B-phase stator set overlapping the A-phase stator set from the other side;
has
The A-phase first core and the B-phase first core are fixed to each of the plurality of stators,
A stepping motor according to claim 1, wherein said B-phase first core and said A-phase first core are fixed so as to overlap at a boundary portion of said plurality of stators. The stepping motor according to claim 1,
The A-phase first core includes: an A-phase annular plate portion overlapping the A-phase coil bobbin from one side; and a phase case,
The B-phase first core includes: a B-phase annular plate portion overlapping the B-phase coil bobbin from the other side; and a phase case,
A first welding mark when the B-phase first core and the A-phase first core overlapping at the boundary portion of the plurality of stators are fixed by welding is formed by the B-phase annular plate portion and the B-phase first core. It exists so as to straddle both the outer surface of the bent portion between the case portion and the outer surface of the bent portion between the A-phase annular plate portion and the A-phase case portion. A stepping motor characterized by: The stepping motor according to claim 2,
The radially outer surface of the bent portion between the A-phase annular plate portion and the A-phase case portion, and the diameter of the bent portion between the B-phase annular plate portion and the B-phase case portion 1. A stepping motor characterized in that both surfaces on the direction outer side are convex curved surfaces curved outward in the radial direction. The stepping motor according to claim 2 or 3,
The stepping motor, wherein the first weld marks are present at a plurality of locations spaced apart in a circumferential direction. In the stepping motor according to any one of claims 2 to 4,
In each of the plurality of stators, the A-phase case portion extends to a position covering the A-phase second core from the radially outer side, and the B-phase case portion extends to a position covering the B-phase second core. from the radially outer side, and when the first core for the A phase and the first core for the B phase are fixed by welding, the second weld mark of the A phase case portion is the It exists so as to straddle the radially outer surface of the tip portion of the A-phase second core side and the radially outer surface of the tip portion of the B-phase case portion on the side of the second B-phase core. A stepping motor characterized by: The stepping motor according to claim 5,
The stepping motor, wherein the second weld marks are present at a plurality of locations spaced apart in a circumferential direction. In the stepping motor according to any one of claims 2 or 6,
In each of the plurality of stators, the A-phase case portion is formed with an A-phase opening extending in the motor axial direction, and the B-phase case portion is formed with an opening extending in the motor axial direction. to form a B-phase opening that constitutes an opening connected to the A-phase opening,
An A-phase terminal block integrally formed with the A-phase coil bobbin and a B-phase terminal block integrally formed with the B-phase coil bobbin protrude radially outward from the opening. A stepping motor characterized by In the stepping motor of claim 7,
In each of the plurality of stators, the A-phase opening extends throughout the A-phase case portion in the motor axial direction, and the B-phase opening extends across the B-phase case portion. A stepping motor, characterized in that it extends over the entire motor axis direction. In the stepping motor according to any one of claims 1 to 8,
A stepping motor, wherein the plurality of stators have an outer diameter of 6 mm or less. In the stepping motor according to any one of claims 1 to 9,
The stepping motor, wherein the stator section has two stators as the plurality of stators.

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