JPS6369450A - Permanent magnet rotor of hermetic motor for refrigeration compressor - Google Patents

Abstract

PURPOSE:To obtain a permanent magnet rotor for a hermetic motor excellent in cost performance and capable of mass production, by forming a resin magnet of magnetic powder having a composition of R1-x(Fe1-y, By)x and with resin superb in refrigerant-tightness. CONSTITUTION:As a concrete instance of R1-x(Fe1-y, By)x, composite alloy of Nd0.14(Fe0.95, B0.05)0.86 is dissolved and quenched flakes are fabricated by liquid quenching. Magnetic powder is then made available crushed into not larger than about 125mum in particle size. Proper additive is added to this magnetic powder, with which epoxy resin with oil absorptive function is mixed so as to be about 3 weight portion and kneaded to make resin magnet material. With a molding machine this material is molded into a definite shape and heated and hardened after taken out of a metallic mould. This resin magnet 1 is laminated in designated numbers and fixed to an iron core 2 with adhesive to fabricate a permanent magnet rotor.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a permanent magnet rotor for a DC brushless motor used as a motor for a hermetic refrigeration compressor.

Conventional technology The electric motor used in hermetic refrigeration compressors is generally called a hermetic motor, and an induction motor is used, but recently, especially in the air conditioner field, the proportion of heat pumps that can be used for both cooling and heating has increased, and Products equipped with inverters have become widely used for capacity control. In this case, the hermetic motor is an induction motor and a D
A C brushless motor is used. DC brushless motors use permanent magnets in their rotors, and have the advantage of being highly efficient. However, since permanent magnets are used in the rotor, there are drawbacks, and various countermeasures have been proposed. A commonly used permanent magnet is a ferrite type magnet, which has the lowest cost per energy product and is widely used. However, the mechanical strength is insufficient when used as a high speed rotor. Therefore, as a structure to prevent the magnet from being damaged and scattered, for example, in JP-A-58-172376Ji4f, the outer periphery of the permanent magnet was wrapped with resin.
．． No. 1756 proposes a structure in which the outer periphery of the magnet is wrapped with a heat-shrinkable tube, and JP-A-59-201663 proposes a structure in which the outer periphery of the magnet is canopied with a metal cylinder.

Problems to be Solved by the Invention However, these methods cannot be used in environments such as hermetic motors, where a refrigerant such as R-22 and a refrigeration oil such as naphthenic oil coexist and are used under high temperature and high pressure. It may not be possible to ensure mechanical strength, or there may be a risk that the low molecular weight so-called oligomers contained in the resin may be extracted and cause mechanical trouble to the refrigeration compressor, or furthermore, high costs may be avoided. It's something that doesn't exist. The mechanical strength of permanent magnets is based on ferrite or R-Co (here, R
(such as one or more rare earth metals) is compressed from powder and made by sintering or firing, so it is significantly inferior, especially in terms of impact strength. Therefore, with the aim of improving shape freedom and mechanical strength at the expense of magnetic properties,
Resin bonded magnets have been considered and have been put into practical use in a wide range of fields. When viewed as a hermetic motor, the dimensions and shape of the motor are built into a pressure vessel as a compressor, so
Limited. Therefore, based on the energy product of 4.0 MGOe of an anisotropic ferrite magnet, a possible resin bonded magnet is R-C.

It becomes magnetic powder. However, in the R-Co system, R is mainly Srn, which is extremely disadvantageous in terms of cost from a resource standpoint, and from the standpoint of magnetic properties, it must be made anisotropic before use. A magnetic field forming process is indispensable during the process of manufacturing a magnet, and is a cause of reducing manufacturing costs. Furthermore, it cannot be said that the resin used necessarily has excellent refrigerant resistance, and therefore cannot be said to be suitable for use in a hermetic motor.

With the advancement of inverters, there is a strong need for DC brushless motors with excellent cost and efficiency as variable capacity control motors. The present invention solves this problem, and aims to provide a permanent magnet rotor for a hermetic motor that is low in cost and performance and suitable for mass production.

Means for Solving the Problem In order to solve this problem, the present invention provides magnetically isotropic R, I-x(Fe+
-y, By) A resin magnet is formed from magnetic powder having a composition represented by This is a realization of a rotor.

In other words, due to the sufficient mechanical strength of the resin magnet and the good refrigerant resistance of the resin used, it is possible to ensure high reliability without the need for special reinforcing means, and due to its superior magnetic properties. Since the motor as a whole can be made smaller and the total cost of the motor can be lower than conventional ones, a hermetic DC brushless motor with excellent cost and performance can be obtained.

EXAMPLES Hereinafter, details of the present invention will be explained based on examples. The concrete shape is shown in FIG. 1, in which a predetermined amount of resin magnets 1 are laminated and fixed to an iron core 2.

First, R + - x (Fe + - y + By) xs As a concrete example, Ndo, z (F1a, ss, 3o, os) o, e
Melt the composition alloy of e, produce quenched flakes by liquid quenching method, prepare magnetic powder that has been ground to particles with a diameter of about 125μ or less, add appropriate additives to this, and further add oil absorption function. A resin magnet material is made by blending the epoxy resin with approximately 3 layers and kneading it by an appropriate method.

This resin magnet material is molded into a predetermined shape using a molding machine, and then removed from the mold and heated to harden. Since this molding is basically isotropic, magnetic field molding is not required and can be handled with a simple molding machine. The shape in this case is, for example, a ring shape, as shown in Figure 2, but the magnetic properties of the magnet are as follows:
Since it is proportional to the density of the compact, in order to stably obtain a higher density, the pressure surface during pressure molding is influenced by the thickness t of the magnet and the length e after pressure molding. According to the inventor's experiments, it was found that if e was increased relative to t, the specified density could not be obtained even if the pressing force was increased due to friction between the side of the mold and the magnet material during compression, and as a result, e≦
5t, more ideally e=2.5 to 3t, which is the shape to stably obtain high density. Therefore, specifically, a ring resin magnet shown in FIG. 2 with an outer diameter of 50 m and an inner diameter of 446-1t=2-1e=5 was manufactured. A predetermined number of these magnets were stacked to produce a permanent magnet rotor as shown in FIG. Here, the resin magnet 1 is fixed to the iron core 2 with adhesive, but when the iron core 2 is punched out from an electromagnetic mesh plate to form the stator core,
They were formed at the same time, so punching oil is attached to them.

Therefore, do not remove the punching oil (it is preferable to use an epoxy adhesive that absorbs this oil and hardens. However, if it is possible to remove the oil properly, there is no need to take special consideration. , epoxy adhesive with oil absorption function,
It is possible to impart appropriate elasticity to the adhesive layer after absorption hardening and increase its resistance against centrifugal force and peeling force, and is suitable for use in the present invention. Now, when a resin magnet comes into contact with refrigerant gas and refrigerating machine oil that has absorbed the refrigerant at a high temperature of 120 degrees Celsius or less, and is exposed to a high pressure of, for example, 30 kg/cd, the binding resin is originally a low-molecular compound. A phenomenon occurs in which the oligomers contain oligomers and are extracted by a refrigerant, but this phenomenon occurs when the TG is higher than the TG of the resin (
Then it will be accelerated. Therefore, it is preferable that the Tg (glass transition temperature) of the resin is 120° C. or higher, which is the upper limit of the operating temperature. The upper limit of the operating temperature is determined by the polyester film used to insulate the stator and the temperature demagnetization of the magnet.

Effects of the Invention As described above, the permanent magnet rotor of the present invention makes full use of the magnetic powder, binding resin, and overall performance, and eliminates the need for special reinforcing means for the magnets, which conventionally causes high costs. Since it performs one function for hermetic motors without any problems, it is possible to create a DC brushless motor for hermetic motors that is reliable, easy to produce, and low in cost.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a permanent magnet rotor of the present invention, and FIG. 2 is a perspective view showing the shape of a resin magnet for a permanent magnet rotor of the present invention. 1... Resin magnet, 2... Iron core. Name of agent: Patent attorney Toshio Nakao and 1 other person

Claims (4)

[Claims] (1) R_1_-_x(Fe_1_-_y, B_y)_
A magnetic powder having a composition represented by x and which is a quenched fine powder;
A permanent magnet rotor for a motor for a hermetic refrigerating compressor is constructed by fixing a resin magnet made of a resin with good refrigerant resistance to an iron core to bind the magnetic powder. (2) A permanent magnet rotor for a motor for a hermetic refrigerating compressor according to claim 1, wherein the glass transition temperature of the bonding resin is 120° C. or higher. (3) A permanent magnet rotor for a motor for a hermetic refrigerating compressor according to claim 1, wherein the adhesive for fixing the resin magnet to the iron core has oil absorption functionality. (4) The relationship between the axial length l and the thickness t of the resin magnet is l
A permanent magnet rotor for an electric motor for a hermetic refrigerating compressor according to claim 1, which is constructed by laminating a plurality of permanent magnets with a diameter of ≦5t.