JPH11191952A - Stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent with simple construction at low cost the vibration of a stator in a lamination direction in a motor case. SOLUTION: In a state in which a stator is housed in a motor case 11, a protrusion 16c formed on a coil bobbin 16 is pressed against the end surface of a stator core 24, and is furthermore elastically deformed in a lamination direction. A pressing force which presses the stator in the lamination direction in the motor case 11 is given to the protrusion 16c through elastic deformation. Consequently, the vibration of the stator in the motor case 11 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor, and more particularly to a stepping motor in which a pair of stators each having a coil bobbin and a stator core are laminated in a rotor axial direction.

Conventionally, a permanent magnet type (PM type) stepping motor has been widely used as a driving source for controlling an idle speed control device, an exhaust gas recirculation device and the like of a vehicle engine. These stepper motors
Each of the stators has a pair of stators, and a pair of cylindrical coil bobbins around which an exciting coil is wound a plurality of times are sandwiched by a pair of stator cores from the rotor axis direction. The pair of stators are housed in the motor case in a state of being stacked in the rotor axis direction, and the magnet rotor is rotatably disposed so as to face the pole teeth formed on the inner peripheral surface of the stator core. By closing the one end opening of the motor case with the motor housing, the pair of stators and the magnet rotor are completely housed in the motor case.

In general, when a stepping motor is operated, a driving pulse is input, but when the driving pulse is input, a minute vibration is caused in the stator in the motor case due to the effect of the generation of magnetism, and as a result, abnormal noise is generated. There's a problem. In addition, a countermeasure against vibration has been required for a stepping motor disposed in an environment where vibration is likely to occur, such as around an engine of a vehicle.

Therefore, a method is known in which a wave washer is housed in a motor case in order to prevent the minute vibration of the stator, and the vibration of the stator in the laminating direction (rotor shaft direction) is absorbed by the elasticity of the wave washer. I have. However, according to this structure, there is a problem that the number of parts is increased, the number of assembly steps is increased, and the cost is increased.

Further, a stepping motor is known which prevents a minute vibration of a stator in a case by a spring portion formed by cutting and raising the ring portion of an end yoke of the stator (for example, Japanese Unexamined Utility Model Publication No. 2-75981). ). However, even in this method, since the spring portion is formed by cutting and raising, a processing step (e.g., punching) of forming the spring portion is required, and the number of steps is increased.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a stepping motor capable of preventing vibrations in the direction of lamination of a stator in a motor case with a simple structure and at low cost. It is an object.

[0007]

According to a first aspect of the present invention, there is provided a stepping motor comprising a pair of stators having a coil bobbin on which an exciting coil is wound and a stator core which is energized by energizing the coil bobbin to generate a rotating magnetic field. And a rotor that rotates in accordance with the rotating magnetic field, wherein the stepped motor includes a pair of stators stacked in the axial direction of the rotor in a case, wherein the coil bobbin is mounted on the stator core when the stators are stacked. It is characterized in that it has a pressing projection which engages to restrict the movement of the stator core and elastically deforms in the laminating direction to apply a pressing force.

According to the first aspect of the present invention, the pressing projection of the coil bobbin is elastically deformed in the laminating direction to apply the pressing force when the stator is laminated. Therefore, the stator core is pressed in the stacking direction, and it is possible to prevent rattling of the stator in the case. Further, the pressing protrusions engage with the stator core to perform mutual positioning. Therefore, the coil bobbin and the stator core do not resonate by vibrating in the rotor circumferential direction or the rotor radial direction, respectively. The pressing projection is formed by a simple configuration in which the positioning projection is extended in the rotor axis direction (stator stacking direction).

As described above, the coil bobbin and the stator core are positioned by the engagement between the pressing projection and the stator core, and the play of the stator in the stacking direction can be prevented by the pressing force of the pressing projection.

In the stepping motor according to the present invention, the coil bobbin includes a winding portion around which the exciting coil is wound, and a hollow portion formed on an outer peripheral side of the winding portion. It is characterized in that it is formed at a position corresponding to the hollow part.

According to the second aspect of the present invention, since the pressing projection is formed at a position corresponding to the hollow portion of the coil bobbin, elastic deformation in the laminating direction is facilitated, and a sufficient elastic force is obtained. Even if it is elastically deformed, it does not interfere with the exciting coil.

Further, the stepping motor according to a third aspect is characterized in that the pressing projection is formed at an outermost portion of the coil bobbin.

According to the third aspect of the present invention, it is preferable that the pressing projection is provided at an outermost portion of the coil bobbin. By forming it at the outermost part, it becomes easier to elastically deform.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a stepping motor M embodying the present invention will be described below with reference to the drawings.

FIG. 1 shows a stepped motor M according to the present invention, in which a pair of stators 12 and 14 are housed in a cylindrical motor case 11 having a bottom. Stator 1
2 and 14 are provided with resin coil bobbins 16 and 18 around which exciting coils 16 a and 18 a are wound, respectively, and stator cores 20 and 22 and stator cores 24 and 26 provided so as to sandwich each of the coil bobbins 16 and 18. I have. Each stator core 20, 22, 24, 26 has a multiple number of comb-shaped pole teeth at the center. The connector 17 in the motor case 11 includes a plurality of terminals 1.
9 and a dual excitation coil 16 via a terminal 19.
DC power is supplied from a power supply (not shown) to the terminals a and 18a.

A cylindrical magnet rotor 30 is rotatably disposed at the center between the two stators 12 and 14. The magnet rotor 30 has a collar 31 made of resin or aluminum, and a rotor shaft 32 as a rotating shaft is inserted through and fixed to the center of the collar 31. The rotor shaft 32 is rotatably supported at one axial end by a ball bearing 34 and at a substantially axial center by a ball bearing 36. The ball bearing 34 has a bearing 1 whose outer ring is formed at the bottom of the motor case 11.
1a, and is urged by the disc spring 37 together with the rotor shaft 32 (magnet rotor 30) to the other axial end. On the other hand, the ball bearing 36 is supported by a part of the motor housing 13 whose outer ring forms a lid of the motor case 11. Also, the rotor shaft 3
A reduction gear 38 is fixed to the other end of 2.

As shown in FIGS. 3 to 5, the coil bobbin 16 has four cylindrical projections 16c on the end face 16b which project in the rotor axis direction, that is, in the direction in which the stators 12 and 14 are stacked. Specifically, the protrusion 16c
Is formed at a position corresponding to the hollow portion 16d on the outer peripheral side of the winding portion around which the exciting coil 16a is wound. further,
These projections 16c are formed at the radially outermost portion of the end face 16d.

Further, the protrusion 16 of the stator core 22
An engagement hole 22a is formed at a position corresponding to c.
When assembling the stator core 22, the protrusion 16c is positioned by the protrusion 16c and the engagement hole 22a.
Further, the length of the protrusion 16c in the stacking direction is formed sufficiently longer than the thickness of the stator core 22, and protrudes from the engagement hole 22a.

Here, as shown in FIG. 2 (enlarged view of a portion A in FIG. 1), when housed in the motor case 11, the tip of the projection 16 c is attached to the end face of the stator core 24 of the opposed stator 14. It comes into contact. And
In the stacked state, the protrusion 16c is elastically deformed in the stacking direction (downward in FIG. 2). Due to this elastic deformation, the protrusion 16
c applies a pressing force to press the stators 12 and 14 in the laminating direction in the motor case 11 (between the motor housing 13 and the bottom of the motor case 11). Therefore, rattling of the stators 12 and 14 in the motor case 11 can be prevented by the pressing force.

Further, since the projecting portion 16c positions the coil bobbin and the stator core, the coil bobbin 16 and the stator core 22 do not shift in the rotor circumferential direction or the rotor radial direction, respectively. The protrusion 16c has a simple configuration in which a protrusion for positioning is extended in the rotor axis direction (stacking direction). Therefore, it is possible to prevent rattling in the stacking direction of the stator at low cost.

Further, the length (projection amount) of the projection 16c is arbitrarily set, but the pressing force can be increased by increasing the length. Further, in the present embodiment, since the protrusion 16c is formed at the radially outermost portion of the end face 16e, the protrusion 16c is easily elastically deformed. Moreover, since the projection 16c is formed at a position corresponding to the hollow 16d, the projection 1c is elastically deformed.
6c does not interfere with the exciting coil 16a.

While the projection 16c of the coil bobbin 16 has been described above, as shown in FIG.
Similarly to the above-described coil bobbin 16, the four protrusions 18c
Are formed. Then, the projection 16c and the projection 18
c are laminated so as to face each other. The protrusion 1
8c is formed at a position where it does not interfere with the protrusion 16c when the coil bobbins 16, 18 are stacked with their sides on which the protrusions are formed facing each other.

When the projection 18c is housed in the motor case 11, the tip of the projection 18c is laminated and comes into contact with the end face of the stator core 22 of the opposed stator 12, so that the projection 18c extends in the laminating direction. It can be elastically deformed. Due to this elastic deformation, the projection 18 c applies a pressing force for pressing the stators 12 and 14 in the motor case 11 (between the motor housing 13 and the bottom of the motor case 11). Therefore, rattling of the stators 12 and 14 in the motor case 11 can be prevented.

Further, the projecting portion 18c is
The coil bobbin 18 and the stator core 24 do not slide in the circumferential direction of the rotor or in the radial direction of the rotor. The projection 18c is formed with a simple configuration in which the positioning projection extends in the stacking direction. Therefore, it is possible to prevent rattling in the stacking direction of the stator at low cost.

In this embodiment, the coil bobbin 1
The projections 16c and 18c are 4
Although formed at locations, the number of protrusions 16c and 18c is not limited. In addition, the protrusions 16c and 18c are formed on one end surface of each of the coil bobbins 16 and 18. However, the present invention is not limited thereto.

Next, a modified example of the coil bobbin will be described with reference to the drawings. As shown in FIGS. 6 and 7, an arc-shaped projection 16 f may be provided on the end face 16 b of the coil bobbin 16. The protrusions 16f are provided at three places, but are not limited thereto. The projection 16f is the same as the projection 1
6c (18c), the hollow portion 16 of the coil bobbin 16
d, and the operation is the same as that of the protrusion 16c.

As described above, in the stepping motor of the present invention, the coil bobbin and the stator core are positioned by the engagement between the pressing projection and the stator core, and the rattling of the stator in the stacking direction is caused by the pressing force of the pressing projection. It has the effect that it can be prevented. In addition, since the pressing projections also serving as positioning can be formed with a simple configuration, it is possible to achieve inexpensive prevention of rattling in the stacking direction of the stator.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a stepping motor according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a portion A in FIG.

FIG. 3 is a plan view showing a coil bobbin.

FIG. 4 is a plan view showing a stator core.

FIG. 5 is an exploded sectional view of the stator.

FIG. 6 is a plan view showing a modified example of the coil bobbin.

7 is a plan view showing a modified example of the stator core taken along the line XX of FIG. 6;

[Explanation of symbols]

 M Stepping motor 11 Motor case (case) 12, 14 Stator 16, 18 Coil bobbin 16a, 18a Excitation coil (winding part) 16c, 16f, 18c Projection (pressing projection) 16d Hollow part 20, 22, 24, 26 Stator core 30 Magnet rotor (rotor)

Claims (3)

[Claims] 1. A case comprising: a pair of stators having a coil bobbin on which an exciting coil is wound, a stator core that is excited by energizing the coil bobbin to generate a rotating magnetic field, and a rotor that rotates in accordance with the rotating magnetic field; A stepping motor in which the pair of stators are laminated in the axial direction of the rotor, wherein the coil bobbin engages with the stator core in the laminated state of the stator to regulate the movement of the stator core, and in the laminating direction. A stepping motor having a pressing projection for applying a pressing force by being elastically deformed. 2. The coil bobbin includes a winding portion around which the exciting coil is wound, and a hollow portion formed on an outer peripheral side of the winding portion, and the pressing protrusion is formed at a position corresponding to the hollow portion. The stepping motor according to claim 1, wherein: 3. The stepping motor according to claim 1, wherein the pressing projection is formed at an outermost portion of the coil bobbin.