JPH0145234Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a stepping motor, and relates to the structure of a stator core constructed by laminating steel plates.

[Technical background of the invention]

The stator core of a conventional stepping motor of this type is made by laminating core pieces formed by punching silicon steel plates, and inserting rivets into rivet insertion holes formed in the laminated core in the stacking direction. A structure is adopted in which the parts are crimped and integrated.

In this structure, as shown in Fig. 4, stress is concentrated on the caulked part of the iron core 1 by the rivet 2,
The flatness of the end face of iron core 1 is poor, and the rivet 2
Since there is a gap between the inner periphery of the rivet insertion hole 3 formed in the iron core 1 through which the rivet is inserted and the outer periphery of the rivet 2, the iron core 1 is distorted when an external force is applied.
This causes a decrease in the stepping motor's torque characteristics, step angle accuracy, and detent torque.

Then, the inner and outer peripheries of the core are laminated and polished, and the gap between the rotor and the poles of the core is reduced to 0.08.
The accuracy of the gap size is increased by maintaining the gap at about 0.1 to 0.1 to maintain a uniform gap and ensure that the gap is securely fitted to the casing. It has the disadvantage that blistering occurs in the stacking direction.

For this reason, a structure has been adopted in which the core is laminated and is caulked with rivets and then bonded with an adhesive to increase the strength of the core, but this has the disadvantage of increasing cost.

[Purpose of invention]

The present invention was developed in view of the above-mentioned drawbacks, and provides a stepping motor that improves the flatness of the end face of a stator core constructed by laminating, eliminates the risk of distortion, and has excellent torque characteristics and step angle accuracy. It is something.

[Summary of the idea]

The structure of the present invention consists of a rectangular stator core with a substantially square frame shape, which has a plurality of comb-like poles formed at the tip corresponding to the step angle, and poles protruding from the inner periphery for winding coils; a rotor that is rotatably fitted to the child core and has comb-like poles formed on its circumferential surface in accordance with step angles corresponding to the poles of the poles; and a pair of rotors that are fitted to the stator core from both ends, respectively. The stator core is constructed by laminating stamped steel plates such as silicon steel plates, and is welded in the lamination direction to at least one side of the outer circumferential arc-shaped portion into which the stator core casing is fitted. forming a protrusion,
This welding protrusion is welded and the laminated iron core is integrated without being caulked with rivets.

[Example of idea]

Next, the structure of an embodiment of the present invention will be explained with reference to FIGS. 1 and 2.

Reference numeral 10 denotes a stator core, which is constructed by laminating core pieces punched from silicon steel plates, and is formed into a substantially square frame-like rectangular shape, with a pole 12 protruding from the substantially central portion inside each side portion 11. A plurality of comb-shaped poles 13 are formed at the tip of each pole 12 in accordance with the respective step angles. A welding protrusion 16 is formed on one side of the outer circumferential arc-shaped part 14 at each corner of this core 10 by two parallel grooves 15, 15 in the stacking direction, and this welding protrusion 16 is welded. The stator core 10 is constructed by integrating the laminated core pieces. Tightening screw insertion holes 17 are formed in each corner of this iron core 10 .

Next, 19 is a rotor, which is rotatably disposed in the hollow portion of the stator core 10. This rotor 19 is composed of a disk-shaped permanent magnet 20 and magnetic bodies 21, 21 that sandwich this permanent magnet 20. On the outer peripheral surface of these magnetic bodies 21, 21, tooth-shaped poles are arranged at step angles. It is formed accordingly. A rotating shaft 23 that passes through this rotor 19 and is fixed has a bearing 2.
2 and 22 are provided.

Reference numerals 25 and 25 denote casings, and each of the casings 25 and 25 has a fitting protrusion 26 projecting from each corner to fit into the outer circumferential arc-shaped portion 14 of the corner of the stator core 10. It is fitted on both sides and secured with screws. This casing 25,
A bearing holding portion 27 into which the bearings 22, 22 are fitted is formed in the center of the bearing 25.

When the coils wound around each pole 12 of the stator core 10 are sequentially excited, the poles of the poles 12 are alternately switched to N and S poles, and the rotor 19 is rotated by a step angle.

The stator core 10 is formed by welding the welded protrusions 16 of the laminated core pieces together and then polishing the inner and outer peripheries of the core 10 by machining. During this grinding process, the iron core 10 has no stress concentration area due to caulking, no bulging occurs due to grinding, and no distortion occurs in the iron core 10 due to external force.
The gaps between each pole 12 of the iron core 10 and the rotor 19 can be made uniform.

In the above embodiment, a structure in which a welding protrusion 16 was formed on one side of the outer circumferential arcuate part 14 at each corner of the iron core 10 was explained, but as shown in FIG. It is also possible to form portions 16, 16 to further improve dimensional accuracy and mechanical strength.

[Effect of idea]

According to the present invention, a welding protrusion is formed in the stacking direction on at least one side of the outer circumferential arc-shaped part of the corner of the laminated fixed core, and this welding protrusion is welded to integrate the core. The flatness of the inner and outer circumferential surfaces of the core is improved, the core does not warp even when external forces are applied, and dimensional accuracy is improved. The gap between the poles and the rotor can be made uniform, torque characteristics and step angle accuracy can be improved, and the stator core can be manufactured at low cost.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a stepping motor showing one embodiment of the present invention, Fig. 2 is an exploded perspective view of a part of the same, Fig. 3 is a plan view of a stator core showing another embodiment, and Fig. 4 is a cross-sectional view of a stepping motor showing an embodiment of the present invention. The figure is a cross-sectional view of a part of a conventional stator core. 10...Stator core, 12...Pole, 13...
...Pole, 14...Outer circumferential arc-shaped portion, 16...Welding protrusion, 19...Rotor, 25...Casing.

Claims (1)

[Scope of utility model registration request] A rectangular stator core with a substantially square frame shape has a plurality of comb-shaped poles formed at the tip corresponding to the step angle, and a ball around which a coil is wound protrudes from the inner periphery. The rotor is fitted with a rotor having comb-like poles formed on its circumferential surface according to step angles corresponding to the poles of the poles, and a pair of casings that are fitted with the stator core from both ends, The stator core is constructed by stacking stamped steel plates, and a welding protrusion formed in the stacking direction is welded to at least one side of an arcuate outer circumferential portion into which the casing of the stator core is fitted. Stepping motor.