JPS62181638A - Resin mold type stepping motor - Google Patents

Abstract

PURPOSE:To make it possible to seal a stator winding using an extrafine wire and to contrive higher productivity by integrally forming a bearing housing into a stator portion with thermal plastic fiber reinforced polyethylenetere phthalate resin. CONSTITUTION:A stator winding is sealed up by a bearing housing 13 integrally resin-molded together with a stator 1. In this case the bearing housing 13 is formed with a thermal plastic fiber reinforced polyethyleneterephthalate resin where the combination amounts (portions) of e.g. the polyethyleneterephthalate, crystalization accelerator, low-temperature shrinkage agent, thermal-resistant processor and impact resistant improvement agent are 100, 1, 20, 20 and 5, while the combination amounts (%) of the glass fiber, beads or disc filler, thermal stabilizer and carbon black are 15, 25, 0.1 and 0.3. Thus, the low-pressure- sealed molding can be implemented, so that the coil sealing without burnout, etc. is all right even if an extrafine wire is used for winding; higher productivity can be worked for accordingly.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a stepping motor used in office equipment and industrial equipment.

2. Description of the Related Art In general, a configuration shown in FIGS. 2(a) and 2(b) is known for a hybrid stepping motor. The structure will be explained below based on the drawings. Reference numeral 1 denotes a stator having a magnetic pole 2 with a plurality of magnetic pole teeth (not shown) formed on the inner periphery. A stator winding 4 is wound thereon. Reference numeral 5 designates a pair of housings that support the stator l, with a rotating shaft 6 in the center.
A holding part 5 for mounting a bearing 7 that rotatably supports the
a is formed. A rotor 8 is fixed to a rotating shaft 6 facing the stator 1, and is composed of a permanent magnet 9 and a rotor core 10 located on both sides of the permanent magnet 9 and having a plurality of magnetic pole teeth corresponding to the magnetic pole teeth of the stator. It consists of

Reference numeral 11 is an insulating material for insulating the stator winding 4 and the housing 5, and covers the stator winding 4.

Problems to be Solved by the Invention However, the above configuration has the following drawbacks.

(1) Insulation treatment after stator winding is difficult to automate and requires a lot of effort.

(2) There are a large number of assembled parts, and in order to achieve coaxiality between the stator inner periphery and the rotor rotating shaft, the processing accuracy of each part must be increased, which causes an increase in cost.

In recent years, as a solution to these problems, there has been an increasing trend in the number of stepping motors that employ a method in which the stator trunk is encapsulated with a thermosetting resin (for example, unsaturated polyester or epoxy resin) and a portion of the housing is simultaneously molded. However, as is known, this method using a thermosetting resin has the disadvantage of poor productivity and high equipment and mold equipment costs.

On the other hand, the method using thermoplastic resin is difficult to put to practical use in stepping motors that use ultra-thin wire-wound coils because the resin filling pressure during injection molding tends to damage the wire-wound coil insulation film and cause wire breakage. Ta.

The performance required for coil-encapsulated thermoplastic resin is the basic performance required of conventional thermosetting resin, such as high electrical insulation, dimensional stability, heat shock resistance, and mechanical strength. The most important point is that the filling pressure is low.

The breaking stress (F) of the polyurethane copper wire (linear 0.1 mm) of commonly used stepping motors is 3.
X10"N/r& (0,310,062πkg/stress 2) Stress generated during polymer flow; 〇-η ・dy / dχ (dy/dχ= 4 Q
, /'πR2), F>O is required.

On the other hand, since most of the housing of the motor is made of resin, heat shock resistance and dimensional stability are required. The following table shows examples of materials used in conventional molded stepping motors and examples of their various characteristics.

The results are as shown in Table 1, and it is desired to develop a thermoplastic resin material that satisfies the properties shown in Table 1.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides fiber-reinforced polynylene terephthalate based on thermoplastic polyethylene terephthalate (PET) resin, which has a low melt viscosity and excellent dimensional stability. Using (FR-PET) resin, it is possible to mold the bearing housing into a stator T) by enclosing the coils of the ultra-fine winding stator and the housing, significantly improving productivity compared to methods using thermosetting resin. It becomes possible.

Embodiment FIG. 1 shows an embodiment of the present invention. Note that components that are the same as those in the conventional configuration described above will be described with the same reference numerals.

In the figure, 1 is a stator around which a winding 4 is wound, and the winding 4 is insulated from the stator 1 by an insulating frame 3. 1
A boss 2 supports a bearing 7 that rotatably supports the rotating IpH 16, and is fixed by a bearing housing 13 that is molded with resin integrally with the stator 1. This resin molded bearing housing 13 is the winding &'i14 of the stator 1.
It has a structure in which the motor flange 14 is completely sealed and assembled by welding and caulking via the magnetic shield link 15. Reference numeral 16 denotes a boss for attaching and holding the bearing 7 of the output side rotating shaft to the 7 flange 14, and is made of the same resin as the bearing housing 5, and is configured to maintain the accuracy of the rotating shaft.

Next, the structure of the bearing housing 13 will be explained.

Table 2 shows basic formulation examples of resins used for the bearing housing 13. Table 3 summarizes the effects of the resin used in the bearing housing 13 of the present invention and conventional resins on moldability and quality.

Table 2 Table 3 Comparison of equivalent class resins containing 15% glass fiber and 25% other fillers. Further, with resin containing 20% or more of glass fiber, coil breakage and layer shorting occurred.

Effects of the Invention As is clear from the above description, the present invention provides the following effects.

1) Thermoplastic resins are difficult to use, such as polyurethane copper wires. Compared to the method using resin, productivity can be significantly improved.

2) Since it is a thermoplastic resin, ultrasonic welding and thermal welding are possible in the assembly structure, and auxiliary materials such as adhesives and screws are not required, so the assembly process can be streamlined.

3) Due to the above advantages, it is possible to provide an inexpensive and high quality stepping motor.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a resin-molded stepping motor showing an embodiment of the present invention, and FIG. 2 (a) is a vertical cross-sectional view and a cross-sectional view of a conventional hybrid stepping motor. 1... Stator, 4... Stator winding, 13... Bearing housing.

Claims (1)

[Claims] A resin-molded stepping motor in which a bearing housing made of thermoplastic fiber-reinforced polyethylene terephthalate resin is integrally formed with a stator part that forms a rotating magnetic field in which stator windings are wound around a plurality of magnetic poles.