JPS638706B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for assembling a permanent magnet type stepping motor, and its purpose is to manufacture a high-precision stepping motor with good mass productivity.

FIG. 1 shows a conventional permanent magnet type stepping motor, in which the rotor 1 is composed of a multi-pole magnetized magnet, and the stator is composed of an end yoke 3 surrounding an intermediate yoke 2 and a stator winding 4. It is configured. Conventionally, in a stepping motor having such a structure, the intermediate yoke 2 is constructed by joining two donut-shaped magnetic plates 2a and 2b by spot welding, caulking, etc., as shown in FIG. A plurality of comb-like pole teeth 2a', 2b' are provided on the inner peripheries of the rotor shafts 2a, 2b so as to be parallel to the rotor shaft 5. In addition, the magnetic plates 2a and 2b
As shown in FIG. 2, the pole tooth pitch is shifted and fixed by the step angle of the motor. On the other hand, the end yoke 3 is constructed by combining two cup-shaped magnetic bodies 3a and 3b such that their open ends are joined to each other, and the inner surface has comb teeth located between the comb-like pole teeth of the intermediate yoke 2. Shape pole teeth 3a' and 3b' are provided, respectively. Further, a bearing holding plate 7 for holding a bearing 8 is fixed to each of the cup-shaped magnetic bodies 3a and 3b constituting the end yoke 3. Note that the intermediate yoke 2 and the end yoke 3 are generally fixed by press-fitting or adhesion. Further, the stator winding 4 is housed in a space formed by the intermediate yoke 2 and the end yoke 3.

As is clear from the above structure, conventionally, the intermediate yoke 2 is constructed by fixing two doughnut-shaped magnetic plates 2a and 2b back to back to each other, and then the end yoke 3 is fixed to the intermediate yoke 2 to form a stator. are assembling. The intermediate yoke 2 and end yoke 3 are assembled by press-fitting or similar fitting. For this reason, distortion is likely to occur in the pole teeth of the intermediate yoke 2 and the end yoke 3, but after the stator is assembled, it is difficult to adjust the distortion, misalignment, etc. of the inner diameter of the pole teeth. It was possible. This is because in the conventional method, the stator assembly is performed by fitting an end yoke 3 whose one side is closed with a bearing holding plate 7 to an intermediate yoke 2 fixed in advance, and fitting the opening of the end yoke 3 into the intermediate yoke 2. This is because when the end yoke 3 and the intermediate yoke 2 are fully fitted, the inner diameter portion of the stator assembly becomes a completely closed space, and various adjustments cannot be made from the outside.

It is also difficult to check the concentricity of the two bearings 8, and therefore, the twisting of the rotor shaft 5 can only be confirmed after assembly. The degree is fixed and cannot be adjusted.

The concentricity between the two bearings 8 is the sum of the concentricity of each end yoke 3 and the bearing holding plate 7 and the concentricity of the bearing holding plate 7 and the bearing 8, plus the concentricity of the donut-shaped magnetic plate of the intermediate yoke 2. This is an accumulation of concentricity when fixing 2a and 2b, and it is an accumulation of many parts combinations, making it difficult to ensure manufacturing accuracy. This is a so-called twisting phenomenon peculiar to a two-bearing structure in which each bearing is fixed to a separate component.

The present invention has been made in view of the above-mentioned conventional drawbacks, and one embodiment of the present invention will be described below with reference to FIGS. 3 and 4. FIG. 3 shows one of the two stator assemblies, which includes a cup-shaped magnetic body 3a having comb-like pole teeth 3a' parallel to the rotor shaft 5 on the inner surface constituting the end yoke 3, and shaped magnetic body 3a
A stator assembly 6 is constituted by a donut-shaped magnetic plate 2a constituting an intermediate yoke 2 attached to an end face of the stator winding 4. The outer periphery of the donut-shaped magnetic plate 2a is provided with a positioning protrusion that fits into a notch provided on the outer periphery of the cup-shaped magnetic body 3a. Two stator assemblies assembled in this manner are provided, and as shown in FIG. Outer surface portion 7 of plates or donut-shaped magnetic plates
are fixed by welding or adhesive to form the stator.

According to the above configuration, after the stator assembly is assembled, even if a shift in concentricity of the bearing 8 occurs due to this assembly, the motor can be assembled while checking for twisting of the rotor shaft 5. This is because each stator assembly is assembled without attaching the intermediate yokes 2 to each other in advance. Furthermore, after assembling the stator assembly, the inner diameter and misalignment of the pole teeth caused by this assembly can be adjusted through the opening of the intermediate yoke 2, and from this point of view, a stepping motor with high precision and a small air gap can be used. can be easily produced.

[Brief explanation of the drawing]

Fig. 1 is a cutaway perspective view of a conventional permanent magnet type stepping motor, Fig. 2 is a cutaway perspective view of an intermediate yoke in the same stepping motor, and Fig. 3 is a fixation of a stepping motor according to an embodiment of the present invention. FIG. 4 is a cutaway perspective view of the child assembly, and FIG. 4 is a cutaway perspective view of the stepping motor after the assembly is completed. 2... Intermediate yoke, 2a, 2b... Donut-shaped magnetic plate, 2a', 2b'... Pole teeth, 3... End yoke, 3a, 3b... Cup-shaped magnetic body, 3a', 3
b'... Pole tooth, 4... Stator winding, 5... Rotor shaft, 7... Bearing holding plate, 8... Bearing.

Claims (1)

[Claims] 1. A cup-shaped end yoke having a plurality of comb-like pole teeth parallel to the rotor axis arranged at equal intervals on the inner surface, and a comb-like end yoke attached to one axial end face of the end yoke. an intermediate yoke having comb-shaped pole teeth located between the pole teeth on its inner periphery; and an intermediate yoke fixed to an axial end surface different from the axial end surface of the end yoke to which the intermediate yoke is attached or formed integrally with the end yoke. Two sets of stator assemblies each including a bearing holding plate, a bearing fixed to the bearing holding plate, and a stator winding housed in a space formed between the end yoke and the intermediate yoke, A positioning protrusion is provided on the outer periphery of the end yoke to fit into a notch provided on the outer periphery of the end yoke, and the end surfaces of the intermediate yokes that join the two sets of stator assemblies are not fixed in advance. A method for assembling a stepping motor in which the outer circumferential surfaces of an end yoke or an intermediate yoke of a child assembly that are in contact with the other end yokes or intermediate yokes are fixed to each other and integrated.