JPH04368440A - Rotor - Google Patents

Abstract

PURPOSE:To improve the outside-diameter cutting properties of a rotor, and to increase strength against a heat shock by lowering the content of glass fiber in a PPS resin. CONSTITUTION:In a rotor 1 constituted by winding a binding wire 6 on the outer circumferential section of a permanent magnet 14 and molding a layer, on which the binding wire 6 is wound, with a resin 7, the layer is molded with a polyphenylene sulfide(PPS) resin reinforced by glass fiber at a weight ratio of 10% or less.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a rotor equipped with permanent magnets (hereinafter referred to as magnets) used in inner rotor type electric motors, and in particular, the present invention relates to a rotor equipped with permanent magnets (hereinafter referred to as magnets) used in an inner rotor type electric motor, and in particular, the present invention relates to a rotor equipped with a permanent magnet (hereinafter referred to as a magnet) used in an inner rotor type electric motor. Regarding the rotor.

0002

2. Description of the Related Art Conventionally, the protection structure of the rotor of an inner rotor type electric motor equipped with a magnet having poor mechanical strength, such as a ferrite magnet, has been a problem. In addition, with the trend toward higher speeds of electric motors, countermeasures for centrifugal force resistance of not only ferrite magnets but also magnets located on the outer periphery of the rotor have become an important issue. The protective structure of the magnet is
Depending on the purpose of the electric motor, the determination must be made taking into consideration not only strength, motor characteristics, and cost aspects, but also connection with ancillary structures, etc. For example, in the case of a motor for a hermetic electric compressor, the protective member for the magnet must not only have mechanical strength to withstand centrifugal force, but also a high level of motor efficiency, which affects the performance of air conditioners, etc. In addition, strict sealing performance of the magnet is required to prevent magnet powder etc. from being released into the sealed case.

[0003] As something that can satisfy these demands,
Japanese Patent Application No. 1-183501 (Japanese Unexamined Patent Publication No. 3-49544) and Japanese Patent Application No. 1-27789 previously proposed by the applicant
There is a protective structure disclosed in No. 9. The characteristics of this structure are
A bind wire with excellent tensile shear strength such as stainless steel wire is wound around the outer circumference of the magnet to provide reinforcement against centrifugal force, and a resin mold is applied to cover the outer circumference of the bind wire and the axial end of the magnet. This protects the winding end of the bind wire and seals the magnet. Therefore, with this structure, eddy currents generated within the protective member can be suppressed to reduce stray load loss, while the resin that seals the magnets can prevent the release of magnet powder, etc. It has the advantage that a suitable rotor can be constructed.

[0004] The resin used in the above mold is as follows:
A compound of polyphenylene sulfide (hereinafter referred to as PPS) is suitable, and it is suitable for the following (a) to (d).
Due to reasons. (a) Since it is a thermoplastic resin, it has excellent mass productivity. (b) It has a high heat distortion temperature of 260°C, and has extremely high heat resistance for a thermoplastic resin. (c) It has dimensional stability that exceeds that of thermosetting resins, and also has excellent fatigue resistance and creep resistance. (d) It has excellent chemical resistance comparable to fluororesins. However, on the other hand, since PPS is extremely rigid and brittle, it is generally used after reinforcing its mechanical properties, heat resistance, etc. with glass fibers, inorganic fillers, etc. Glass fiber reinforced PP
S is glass content 45 for tensile strength and impact strength
It shows a maximum value at ~55% (wt%), and the heat distortion temperature is 20
% or more, it shows a substantially constant value at 260°C, and the molding shrinkage rate is quite low and stable at 30% or more. Therefore, in order to efficiently utilize the characteristics of PPS as a general molding material, a compound with a glass fiber content of around 40% is suitable, accounting for most of the demand, and PPS used in the rotor mentioned above. The compound used also has a glass fiber weight ratio of around 40%.

[0005]

[Problems to be Solved by the Invention] Molding fluidity is one of the important factors for injection molding materials. As mentioned above, PPS is used after being reinforced with glass fiber, but as the content of glass fiber increases, the molding fluidity decreases. 3 and 4 are cross-sectional views showing the state in which the rotor work 19 is set in a resin mold. When molding is performed in this way, there is a gap between the outer circumference of the work 19 and the molds 21a and 21b. , it is necessary to provide an excessive clearance to improve the circulation of the resin. As a result, the molded rotor has a thick PPS resin layer on the outer periphery, and if left as is, the magnetic gap will be too large for the motor, deteriorating the characteristics, so it is necessary to remove most of the resin layer by cutting. be. However, since it contains a large amount of glass, machinability is poor, and cutting tools are subject to large wear, requiring frequent tool replacement.
In order to achieve accurate finishing, the number of repetitions of cutting increases, resulting in a problem that a large number of man-hours are required.

[0006] Furthermore, as the content of glass fiber increases, the strength against repeated cooling and heating cycles (so-called heat shock) generally decreases. In the case of a rotor used in a hermetic electric compressor, it is necessary to be able to withstand heat shock in the range of -30°C to +130°C. Cracks easily occur during cooling and heating cycles, which poses a major quality issue.

[0007]

[Means for Solving the Problems] The present invention provides a rotor in which a bind wire is wound around the outer periphery of a magnet, and the wound layer of the bind wire is molded with resin, at a weight ratio of 10.
% or less of PPS resin reinforced with glass fiber.

[0008]

[Operation] According to the inventors' experiments, glass content is 15%.
It was confirmed that the clearance at the time of molding can be set to 1 mm or less when the temperature is below. In this case, if the thickness of the resin layer when the product is completed is 0.5 mm, the cutting allowance is 0.5 mm.
Since the thickness is 5 mm or less, the material yield is improved. Furthermore, wear of the cutting tool is reduced and machinability is improved, to the extent that mass production is not hindered. It was also confirmed that when the glass content was 10% or less, cracks did not occur against heat shocks of -30°C to +130°C, making it possible to form a rotor with stable quality. Therefore, if the glass content is 10% or less, it becomes suitable for mass production in terms of molding fluidity and processability, and it becomes possible to obtain a product with stable quality in terms of heat shock resistance.

[0009] In reinforcing the magnet to withstand centrifugal force, sufficient strength can be obtained by the wound bind wire, so the molding made of PPS resin may focus on obtaining a sealing effect for the magnet. In the case of PPS, it has a tensile strength of about 500 kg・f/cm2 without any glass additives, so it is suitable for rotors used in hermetic electric compressors because it has sufficient strength to withstand the centrifugal force applied to it. are doing. In addition, due to the improved molding fluidity, the gap between the bind wires and the corner portion formed between the bind wire and the outer circumference of the magnet are filled with resin. This effect ensures the centrifugal force resistance of the resin.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 show a plan sectional view and a front sectional view, respectively, of a rotor 1 according to the present invention. In the figure, reference numeral 2 denotes a yoke, which is formed into a thick cylindrical shape by laminating a large number of doughnut-shaped thin iron plates each having a shaft hole 3 and a plurality of caulking pin holes 8. End plates 9 protect both ends of the magnet 4 in the axial direction, are formed into a ring shape from a non-magnetic metal material such as zinc, and are fixed to both ends of the yoke 2 by caulking pins 12. If necessary, a balance weight can be attached to this end plate, or the end plate itself can be made weight-unbalanced in advance.
It may also have a function as a balance weight. 4
are tile-shaped magnets, and a plurality of them are mounted on the outer periphery of the yoke 2 in an evenly distributed manner. When arranging the magnets 4, the magnets 4 are positioned by plate-shaped protrusions 14 provided on the end plate 9. Instead of the protrusion 14 provided on the end plate, a protrusion protruding in the outer radial direction is provided on the outer circumferential portion of the yoke, and the magnet 4
may be positioned. A bind wire 6 is wound around the outer periphery of the magnet 4 to protect the magnet from centrifugal force, and a wire with excellent tensile shear strength such as stainless steel wire is suitable. This bind wire 6 is wound with coarse winding portions 10 wound so as to create a gap between adjacent wires in the transport direction. This is because the bonding force between the resin and the bind wire is improved by filling the gap with the resin. In the embodiment, the entire center portion is roughly wound, but this coarsely wound portion 10 may be provided locally or scattered. On the other hand, the densely wound portions 11 at both ends in the axial direction
, 11 are brazed or welded to fix the wire rods including the winding ends of the bind wire 6.

Reference numeral 7 denotes a PPS resin molded to cover the wound layer of the bind wire 6, and one or both of the injection holes 13, 13 arranged in the end plates 9, 9 facing the gap 5 between the magnets. It fills the gap 5 between the magnets 4, and flows from the gap 5 through the gap between the bind wires to the outer periphery of the wound layer of the bind wire 6, and flows in the circumferential direction to form the bind wire. It is solidified by covering the outer circumference of the wound layer No. 6. This PPS resin 7 is a compound reinforced with glass fibers, and has a glass content of 10% (wt%) or less. This is a value obtained by taking molding fluidity and heat shock resistance into consideration. For example, as another example, in the case of a compound containing not only glass fiber but also other inorganic fillers in PPS, 10 %
It is necessary to control the ingredients and their blending proportions so that they have properties equivalent to or better than those of glass-reinforced compounds.

FIGS. 3 and 4 are cross-sectional views illustrating the resin molding method described above. 19 in the figure is a workpiece to be resin molded, and as shown in FIGS. 1 and 2, an end plate 9 and a magnet 4 are attached to a yoke 2, and a bind wire 6 is wound around the outer circumference of the magnet. represents something. This work 19 is a guide pin 2 inserted into the shaft hole 3 of the yoke.
0, and is held by the upper die 16 and the lower die 22. 21a and 21b are work 1
It is of medium size and is placed on the outer periphery of the workpiece 19, and has a clearance between it and the workpiece 19 to form a predetermined resin layer.
It is formed so as to be separable along parting lines P1 and P2. This clearance has a glass content of 10
% or less, 0.5 mm or more is sufficient, but when cutting the outer diameter after molding, the cutting margin should be taken into consideration.
It should be about 7 to 1.0 mm. The upper die 16 is provided with a runner 17 for supplying molten resin, and a gate 18 is formed continuous with the runner 17. The workpiece 19 is positioned relative to the upper mold 16 so that the gate 18 faces the resin injection hole 13 provided in the end plate 9 of the workpiece 19. As a result, the gate 18 is located between the magnets. It communicates with the gap 5 in the injection direction. With the above configuration, when the resin is injected from the runner 17 through the gate 18, the gap 5 between the magnets is first filled, and from this gap, the resin is passed through the rough winding portion 10 of the bind wire 6, and then the bind wire 6 is wound. The outer periphery of the circuit layer is filled. If concentric accuracy of the rotor's inner and outer diameters is required, the outer diameter is cut after molding. In this case, since the glass content is low, machinability is good, and sufficient accuracy can be obtained with one cutting.

FIG. 5 is a partially enlarged view of the rotor shown in FIG. 2. In the case of PPS resin with a glass content of 10% or less,
The gap between the loosely wound bind wires 6 is almost well filled with the resin 7, and in particular, the resin 7 has penetrated deep into the corner portion 15 formed by the bind wire 6 and the outer periphery of the magnet 4. Due to the anchoring effect of the resin 7 that has entered, a stable product can be obtained in terms of resistance to centrifugal force.

A rotor 1a shown in FIG. 6 shows another embodiment of the rotor manufactured according to the present invention, and shows a cross section corresponding to FIG. 2. In the figure, the same or corresponding parts as in Figure 2,
The same reference numerals as these will be given and the explanation of the overlapping parts will be omitted. The difference from the rotor in Figure 2 is that PPS is used instead of the end plates.
The point is that the end rings 9a, 9a made of resin 7 are integrally formed, and at the same time, the caulking pin is eliminated, and the through holes indicated by reference numeral 8 are filled with resin 7, and the end rings 9a, 9a at both ends are formed.
9a are connected. For resin molding, end rings 9a, 9a are attached to the upper mold 16 and lower mold 22 shown in FIG.
What is necessary is to provide a recess for forming the .

[0015]

[Effects of the Invention] According to the present invention, since the content of glass fiber in the PPS resin is low, the machinability when cutting the outer diameter of the rotor is improved, and the frequency of replacing cutting tools and the number of cutting operations are reduced. This greatly reduces the number of man-hours. Furthermore, since the PPS resin layer on the outer circumference of the rotor can be formed thinly, the yield of materials is good, and at the same time, it is possible to eliminate cutting of the outer diameter. Furthermore, since the strength against heat shock can be improved, a rotor with stable quality for use in a hermetic electric compressor can be provided.

[Brief explanation of the drawing]

FIG. 1 is a plan sectional view of a rotor taken along line Q-Q in FIG. 2, showing an embodiment of the present invention.

FIG. 2 is a front cross-sectional view of the rotor taken along the R-OR line in FIG. 1;

FIG. 3 is a front sectional view of a resin mold die for explaining a rotor manufacturing method.

4 is a plan cross-sectional view of the resin mold cut along line NN in FIG. 3; FIG.

FIG. 5 is a partially enlarged view of the rotor cross section shown in FIG. 2;

FIG. 6 is a front sectional view of a rotor showing another embodiment of the present invention and showing a cross section corresponding to FIG. 2;

[Explanation of symbols]

1, 1a Rotor 2 York 3 Shaft hole 4 Permanent magnet 6 Bind line 7 Resin 9,9a End plate 12　Caulking pin

Claims (1)

[Claims] Claim 1: A rotor constructed by winding a binding wire around the outer periphery of a permanent magnet and molding the wound layer of the binding wire with resin, which is made of polyphenylene sulfide resin reinforced with glass fiber having a weight ratio of 10% or less. A rotor characterized by being molded with.