JPH1098865A - Stepping motor and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fix all the stators to a motor case. SOLUTION: This stepping motor 1 comprises a cup-like motor case 2 having an opening 2a opened at one of an axial direction, one set of inner stators 3 contained in the case 2 so that exciting pole teeth 8 are directed toward both axial sides, one set of outer stators 4 arranged at both axial sides of the stators 3 and directed toward the stators 3 side, and winding bobbins 5 wound with windings sandwiched between the one set of the stators 3 and the one set of the stators 4 opposed to the stators 3. In this case, the stators 3 are fixed by press injecting to the case 2. The stators 4 at the opening 2a side are engaged with the case 2 by gap engaging, and positioned fixedly to the case 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a stepping motor. More specifically, the present invention relates to means for fixing a stator of a stepping motor and a motor case.

[0002]

2. Description of the Related Art As shown in FIGS. 7 to 9, a stepping motor 101 has a cup-shaped motor case 102 having an opening opening at one side in the axial direction, and a motor case 102 housed inside the motor case 102 for exciting. A pair of inner stators 104 and 10 formed so that the pole teeth 103 face both sides in the axial direction.
4 and the pole teeth 105 for excitation, which are disposed on both axial sides of the inner
A pair of outer stators 106, 106 facing the 4,104 side
And a winding bobbin 107 having windings wound between the pair of inner stators 104, 104 and the outer stators 106, 106 facing each other. A rotor 108 is inserted into each of the stators 104 and 106.

When assembling the stepping motor 101, a winding bobbin 107 is inserted through an opening of a motor case 102, inner stators 104 and 104 are inserted, and another winding bobbin 107 is inserted. The outer stator 106 is inserted. In this state, the motor case 102
The main plate 109 is fitted into the opening of the motor 101 and fixed by caulking, bonding or welding to assemble the motor 101 main body.

[0004] When the fitting between the motor case 102 and the stators 104 and 106 is clearance fitting,
In order to prevent the inner circumference of each of the stators 104 and 106 from coming into contact with the rotor 108, it is necessary to provide a large inner diameter in consideration of the rattling movement of each of the stators 104 and 106.
Therefore, the gap between the rotor 108 and the stators 104 and 106 becomes large, and the torque of the motor 101 cannot be improved.

In order to prevent such a situation, the outer diameter of each of the stators 104 and 106 is set so that all the stators 104 and 106 can be tightly fitted to the motor case 102 to minimize the gap.

[0006]

However, as described above, the motor case 102 and the stators 104, 10
6 are fitted by interference fit, only the stators 104, 106 having a larger outer diameter among the inner stators 104, 104 and the outer stator 106 are the motor case 1.
02, and the other stator is fitted with a gap. Therefore, the stators 104 and 106 and the rotor 10
In order to prevent the motor 101 from coming into contact with the motor 8, the inner diameter of the stators 104 and 106 must be increased, which makes it difficult to increase the torque of the motor 101.

Accordingly, an object of the present invention is to provide a stepping motor in which all stators are fixed to a motor case, and a method of manufacturing the same.

[0008]

In order to achieve the above object, the present invention is directed to a cup-shaped motor case having an opening which is opened in one side in the axial direction, and a motor housing which is accommodated in the motor case and which is energized. A set of inner stators formed so that the pole teeth for use are directed to both sides in the axial direction; and a set of outer stators disposed on both sides in the axial direction of the inner stator and for turning the pole teeth for excitation toward the inner stator. A stepping motor having a pair of inner stators and a winding bobbin in which windings are sandwiched between opposed outer stators, wherein the inner stator is fixed to the motor case by press-fitting, and the outer side of the opening side is fixed. The stator is fitted to the motor case by a clearance fit, and is positioned and fixed to the motor case.

Therefore, the inner stator and the outer stator on the opening side are respectively fixed to the motor case. For this reason, since none of the stators rattles to the motor case, even if the inner diameter of each stator is slightly larger than the outer diameter of the rotor, the rotor does not come into contact with each stator.

Further, in the stepping motor according to the second aspect, the outer stator on the opening side is fixed to the motor case by bonding, welding or caulking. Therefore, the outer stator is securely fixed to the motor case.

Further, in the stepping motor according to a third aspect of the present invention, a main plate which is disposed adjacent to the outer side of the motor from the outer stator and closes the opening is fixed to the motor case by bonding, welding or caulking. Therefore,
Since the ground plate is fixed to the motor case, vibration of the opening of the motor case is prevented.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a stepping motor, wherein the excitation pole teeth are formed so as to face both sides in the axial direction in a cup-shaped motor case having an opening opened in one side in the axial direction. After fixing the inner stator of the set by press-fitting, the outer stator on the opening side is fitted into the motor case by clearance fitting, and the outer stator is positioned and fixed at a predetermined position by a positioning jig having a certificate. ing.

Therefore, the inner stator and the outer stator on the opening side are fixed at predetermined positions with respect to the motor case. For this reason, since both stators are positioned with respect to the motor case and no play occurs,
Even if the inner diameter of each stator is slightly larger than the outer diameter of the rotor, contact between the rotor and each stator is prevented.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail based on an embodiment shown in the drawings.

As shown in FIGS. 1 to 7, a stepping motor 1 of the present embodiment comprises a cup-shaped motor case 2 having an opening 2a at one end in the axial direction,
, A pair of outer stators 4, 4 disposed on both axial sides of the inner stator 3, and a pair of inner stators 3, 3. Winding bobbins 5, sandwiched by opposed outer stators 4, 4, respectively.
5 is provided. Then, only the inner stators 3 and 3 are fixed to the motor case 2 by press-fitting, and the outer stator 4 on the opening 2a side is fixed to the motor case 2 by bonding, welding or caulking.

The peripheral wall of the motor case 2 is formed with a terminal opening 2b cut out from the opening 2a side. The excitation pole teeth 6 are folded inward from the bottom side of the peripheral wall of the motor case 2 to form one outer stator 4. However, the outer stator 4 may be attached to the motor case 2 from outside as a separate member. Then, a columnar jig (not shown) which is fitted into the outer stator 4 with almost no gap is inserted. This jig has a reference projection formed at the center of the tip, and fixes the bottom plate 7 to the bottom of the motor case 2 in accordance with the reference projection. This fixing is performed by a method such as welding, bonding, or press-fitting.

The inner stators 3, 3 have a shape in which a hole is formed at the center of a substantially circular plate, and the exciting pole teeth 8 project in the same direction along the axial direction from the inner peripheral edge thereof. I have. And the exciting pole teeth 8 of the two inner stators 3
The surfaces on which are not formed are closely fixed to each other.
As the fixing means, press-fitting, bonding, welding, or the like in which concaves and convexes formed so as to fit with each other are combined is preferable. However, the two inner stators 3 and 3 are not limited to being integrated, but may be formed separately from each other.

Here, the outer diameter of the inner stator 3 is made slightly larger than the inner diameter of the motor case 2. That is,
The inner stator 3 is pressed into the motor case 2 and fixed. When the two inner stators 3 are provided separately, the outer diameters of the inner stators 3 are made equal to each other to be slightly larger than the inner diameter of the motor case 2 so that both inner stators 3 are formed. It can be fixed by press fitting.

Further, it is preferable that the exciting pole teeth 8 of each of the inner stators 3, 3 are shifted from each other. When the inner stator 3 is housed in the motor case 2, the housing angle of the inner stator 3 is set such that the exciting pole teeth 8 of the inner stator 3 and the exciting pole teeth 6 of the outer stator 4 are alternately shifted. Have been.

Like the inner stator 3, the outer stator 4 on the side of the opening 2a has a hole formed in the center of a substantially circular plate, and has an inner peripheral edge for exciting in the same direction along the axial direction. The pole teeth 6 have a protruding shape. The outer diameter of the outer stator 4 is slightly smaller than the inner diameter of the motor case 2. That is, the outer stator 4 is
Is fitted by a clearance fit. When the outer stator 4 is housed in the motor case 2, the exciting pole teeth 6 of the outer stator 4 and the exciting pole teeth 8 of the inner stator 3
Are set so that the outer stator 4 is staggered.

The outer stator 4 is fixed to the motor case 2 by welding. As fixing means,
Fixing means other than welding, such as bonding and caulking, may be used. Since the motor case 2 of the present embodiment is formed with the terminal opening 2b, the opening 2a easily spreads in the circumferential direction as it is, and has a sufficient holding force when the main plate 9 is fixed to the motor case 2 by caulking. Although it is difficult to obtain, by fixing the outer stator 4 to the opening 2a by welding or the like, the holding force when the main plate 9 is swaged to the opening 2a can be increased. However, it goes without saying that the outer stator 4 may be fixed to the motor case 2 by caulking.

Further, a ground plate 9 is fitted outside the outer stator 4 of the motor case 2. The base plate 9 is positioned by fitting a hole 4a formed in the outer stator 4 with a projection 9a formed in the base plate 9. The positioning method is not limited to the fitting between the hole 4a and the projection 9a, and the positioning is performed by the outer peripheral edge of the base plate 9 contacting the inner peripheral surface of the motor case 2 without forming the hole 4a and the projection 9a. No problem.

The main plate 9 and the motor case 2 are fixed by welding. Thereby, the vibration of the base plate 9 can be prevented very reliably. However, the fixing means is not limited to welding, and may be fixed by bonding or caulking.

A winding bobbin 5 is sandwiched between the inner stator 3 and the outer stator 4. The rotor 10 is inserted into the inner peripheral side of each of the stators 3 and 4 by gap fitting. The rotating shaft 11 of the rotor 10 is
Are supported by a bottom plate 7, a base plate 9 and a bearing fitting 12 attached to each central portion.

The procedure for assembling the above-described motor 1 will be described below.

The winding bobbin 5 is inserted into the motor case 2 to which the bottom plate 7 is fixed. The winding bobbin 5 is held by the outer stator 4 inside the motor case 2. Then, the inner stators 3, 3 are inserted into the motor case 2, and the winding bobbin 5 is sandwiched together with the outer stator 4 on the bottom side of the motor case 2. At this time, the inner stator 3 is fixed in the motor case 2 by press fitting. Further, the winding bobbin 5 and the outer stator 4 are sequentially inserted into the motor case 2. This allows
The winding bobbin 5 is sandwiched between the inner stator 3 and the outer stator 4. At this time, the inner stators 3 and 3 are fixed to the motor case 2 by press-fitting, whereas the outer stator 4 on the opening 2a side is clearance-fitted to the motor case 2 so that the position is determined. Not done.

Here, as shown in FIGS. 3 and 4, a cylindrical positioning jig 13 having an outer diameter substantially equal to the outer diameter of the rotor 10 is inserted into the inner periphery of each of the stators 3 and 4. Then, the outer stator 4 on the opening 2a side is positioned, and the outer stator 4 is fixed to the motor case 2 by welding in this state. The welding can be spot welding, plasma welding, laser welding, or the like. However, the fixing means is not limited to welding, but may be bonding or caulking. After the fixing of the motor case 2 and the outer stator 4 is completed, the positioning jig 13 is removed. At this point, the center lines of the inner peripheral portions of the stators 3 and 4 are aligned with each other, and
Is fixed with respect to the motor case 2. Then, the bearing fitting 12 is attached to the bottom plate 7, and each stator 3, 3 is mounted.
The rotor 10 is inserted into the inner peripheral portion of the shaft 4 and the rotating shaft 11 is inserted into the bearing 12.

Thereafter, as shown in FIG.
Is fitted into the motor case 2 and is brought into close contact with the outer stator 4. Note that in FIG.
The illustration of 0 and the winding bobbin 5 is omitted. At this time, the projection 9a of the main plate 9 is fitted into the hole 4a of the outer stator 4.
Thereby, the position of the main plate 9 is determined. Therefore,
Even if the ground plate 9 is fitted into the motor case 2 with a gap, the center line of the ground plate 9 and the center lines of the stators 3 and 4 can be matched. Then, in this state, the main plate 9 is fixed to the motor case 2 by welding. However, the fixing means is not limited to welding, but may be bonding or caulking. Here, the base plate 9 and the outer stator 4 are connected to the projection 9a and the hole 4 respectively.
Since the positioning is performed by fitting with a, even if each fixing means is applied, the position of the main plate 9 does not shift.

As described above, according to the present embodiment, the inner stator 3 is fixed to the motor case 2 by press fitting, the outer stator 4 on the opening 2a side is fixed to the motor case 2 by welding or the like, and the bottom plate 7 side The outer stator 4 is formed integrally with the motor case 2, so that all the stators 3, 4
Are fixed to the motor case 2 and the positioning of the outer stator 4 is performed by a positioning jig 13 having an outer diameter substantially equal to the outer diameter of the rotor 10. For this reason, rattling does not occur in each of the stators 3 and 4,
In addition, since the positioning jig 13 fixes the rotor to an appropriate position with respect to the rotor 10, even if the inner diameter of each of the stators 3 and 4 is formed to be slightly larger than the outer diameter of the rotor 10,
The stators 3 and 4 do not come into contact with the rotor 10.
Therefore, the torque of the motor 1 can be improved by reducing the inner diameter of each of the stators 3 and 4 as much as possible without contacting the rotor 10 and reducing the gap between each of the stators 3 and 4 and the rotor 10.

The above embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the spirit of the present invention.

[0031]

As is apparent from the above description, in the stepping motor according to the first aspect, the inner stator is fixed to the motor case by press fitting, and the outer stator on the opening side is fitted to the motor case by gap fitting. The inner stator and the outer stator on the opening side are fixed to the motor case, respectively. For this reason, neither of the stators causes a backlash to the motor case,
Even if the inner diameter of each stator is slightly larger than the outer diameter of the rotor, the rotor does not come into contact with each stator. Therefore, the inner diameter of the stator can be made as small as possible without contacting the rotor, and the gap between the stator and the rotor can be made small to increase the torque of the motor.

In the stepping motor according to the second aspect, the outer stator on the opening side is fixed to the motor case by bonding, welding, caulking, or the like. Fixed. Thereby, the rigidity of the motor can be increased.

Further, in the stepping motor according to the third aspect, the main plate which is disposed adjacent to the outer side of the motor from the outer stator and closes the opening is fixed to the motor case by bonding, welding or caulking. Vibration of the main plate can be prevented. The rigidity of the motor can be further increased by fixing the main plate and the outer rotor to the motor case.

According to a fourth aspect of the present invention, there is provided a stepping motor manufacturing method, wherein the excitation pole teeth are formed so as to face both sides in the axial direction in a cup-shaped motor case having an opening opened in one side in the axial direction. After fixing the inner stator of the set by press-fitting, the outer stator on the opening side is fitted into the motor case by clearance fitting, and the outer stator is positioned and fixed at a predetermined position by a positioning jig having a certificate. Therefore, the inner stator and the outer stator on the opening side are fixed at predetermined positions with respect to the motor case, respectively. For this reason, any of the stators is positioned with respect to the motor case and does not rattle, so that even if the inner diameter of each stator is slightly larger than the outer diameter of the rotor, contact between the rotor and each stator can be prevented. Therefore, the inner diameter of the stator can be made as small as possible without contacting the rotor, and the gap between the stator and the rotor can be made small to increase the torque of the motor.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a stepping motor according to the present invention.

FIG. 2 is an exploded view showing a motor case, an inner stator, and an outer stator of the stepping motor according to the present invention.

FIG. 3 is a longitudinal sectional view showing a state where a positioning jig is attached to a motor case accommodating each stator.

FIG. 4 is a plan view showing a state where a positioning jig is attached to a motor case accommodating each stator.

FIG. 5 is a longitudinal sectional view showing a state in which a main plate is attached to a motor case accommodating each stator.

FIG. 6 is an exploded view showing the entire stepping motor.

FIG. 7 is a longitudinal sectional view showing a conventional stepping motor.

FIG. 8 is an exploded view showing a motor case, an inner stator, and an outer stator of a conventional stepping motor.

FIG. 9 is a perspective view showing a conventional connection between an outer stator and a winding bobbin.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Motor 2 Motor case 3 Inner stator 4 Outer stator 5 Winding bobbin 6 Outer stator exciting pole teeth 8 Inner stator exciting pole teeth 9 Base plate 10 Rotor

Claims (4)

[Claims] 1. A set of a motor case having a cup-like shape having an opening opening at one side in the axial direction, and a pair of excitation pole teeth housed in the motor case and formed so as to face both sides in the axial direction. A stator, a pair of outer stators disposed on both axial sides of the inner stator, and having exciting pole teeth facing the inner stator; and an outer stator opposed to the pair of inner stators. The inner stator is fixed to the motor case by press fitting, and the outer stator on the opening side is fitted to the motor case by gap fitting. And a stepping motor which is positioned and fixed with respect to the motor case. 2. The stepping motor according to claim 1, wherein the outer stator on the opening side is fixed to the motor case by bonding, welding, or caulking. 3. The motor case according to claim 1, wherein a main plate disposed adjacent to the outer side of the motor from the outer stator and closing the opening is fixed to the motor case by bonding, welding or caulking. 2. The stepping motor according to 2. 4. After fixing a set of inner stators formed so that excitation pole teeth face both sides in the axial direction in a cup-shaped motor case having an opening opened at one side in the axial direction, A method of manufacturing a stepping motor, comprising: fitting an outer stator on the side of the opening to the motor case by gap fitting, and positioning and fixing the outer stator at a predetermined position by a positioning jig having a certificate.