JPH0678480A - Magnet rotor - Google Patents

Abstract

PURPOSE:To improve the quality of a rotor by eliminating an axial deviation of a magnet even when fixing of the magnet by a metal tube is insufficient in a magnet rotor having a yoke core, a magnet mounted on an outer periphery of the core, a metal tube engaged with an outer periphery of the magnet and an end plate covering an axial end of the magnet. CONSTITUTION:A magnet 2 is so formed that its axial length is shorter than the length of a yoke core 1 to be mounted, and an end of the tube 3a is bent to a bore side so that an outer periphery of an end plate 4a is submerged in a step of the magnet 2 and the core 1 in contact with the magnet 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor of an electric motor used in a hermetic compressor, and more particularly to a rotor provided with a permanent magnet field.

[0002]

2. Description of the Related Art A rotor equipped with a magnet for use in a hermetic compressor is intended to reinforce the magnet so that the magnet does not scatter due to centrifugal force and to seal the magnet powder and the like so as not to leak to the outside of the rotor as much as possible. The protective member covers the outer peripheral portion of the rotor and both axial end portions of the rotor.

8 and 9 are sectional views showing the structure of the rotor, which is disclosed in, for example, Japanese Patent Application Laid-Open No. 2-246748. In this rotor, a plurality of tile-shaped magnets 2 are arranged on the outer peripheral portion of a thick-walled cylindrical yoke iron core 1, a thin metal tube 3 is fitted on the outer peripheral portion of the magnet 2, and the axis of the magnet 2 is End plates 4 and 4 are attached to both ends in the direction.

The yoke iron core 1 has a shaft hole 6, a clamp pin insertion hole 7, and a protrusion 8 for positioning a magnet. Generally, a large number of circular thin iron plates are laminated and a caulking clamp portion 13 is provided between the thin iron plates. It is formed by tightening and fixing. The magnets 2 are roof tile pieces formed of a hard magnetic material such as ferrite. A plurality of magnet pieces are arranged in a substantially equal arrangement and fixed by fastening the metal tube 3.

The metal tube 3 is for reinforcing the centrifugal force and for sealing the outer peripheral portion. Since it is excellent in tensile strength and a non-magnetic material is suitable, stainless steel or the like is generally used, and a plate-shaped material is used. Is rolled into a tubular shape by welding and then fitted by shrink fitting or press fitting or a combination of both. The end plates 4 and 4 seal both axial end portions of the magnet 2, and metal circular flat plates are used. The end plates 4 and 4 and the metal tube 3 are clearance-fitted, and the end plates 4 and 4 and the yoke core 1 are fixed to each other by a plurality of clamp pins 9 that axially penetrate through each other. There is. Reference numeral 10 is a bent portion formed by bending the end portion of the metal tube 3 toward the inner diameter side. By providing such a bent portion 10, the gap with the end plate 4 is reduced and the sealing effect is improved. The pipe 3 is being prevented from coming off.

[0006]

Since each member constituting the rotor has a variation in finished dimension, it is necessary to consider the variation in assembling.
In the relative relationship between the axial lengths of the yoke core 1 and the magnet 2, each has a variation in the finished dimension of about 1%. Therefore, in general, the lower limit of the dimension of the yoke core 1 is set to the dimension of the magnet 2. The dimensions of the two are determined so that the upper limit of is not exceeded. For this reason, steps 5 and 5 are generated between the magnet 2 and the yoke core 1, and the magnet 2 and the end plates 4 and 4 are formed.
There will be a gap between and.

The above-mentioned variation in the finished dimension is remarkable also in the relative relationship between the outer diameter of the magnet 2 and the inner diameter of the metal tube 3. Due to these variation, the interference in the fitting of the two greatly changes. If this interference is too small, the tightening force of the metal tube 3 against the magnet 2 becomes weak,
The fixation of the magnet 2 will be insufficient. As a result, as described above, since a gap is created between the magnet 2 and the end plates 4 and 4, the magnet 2 is axially displaced by the operation of the electric motor, and iron powder or magnet powder is produced due to abrasion. However, these leak to the outside of the rotor through the gap between the end plate 4 and the metal tube 3.

Further, there is a problem that vibration and noise increase due to the axial displacement of the magnet 2 or that the balance of the rotating system is lost and vibration and noise are more likely to be generated.

[0009]

According to the present invention, the axial length of the magnet is made shorter than the length of the yoke core, and the end portion of the metal tube is bent toward the inner diameter side so that the outer diameter portion of the end plate is defined as described above. It is configured such that the magnet and the yoke iron core are depressed into a step and brought into contact with the magnet. The step between the magnet and the yoke core may be provided at both ends in the axial direction of the magnet, or may be provided only at one end.

[0010]

Since the outer diameter portion of the end plate is in contact with the end portion of the magnet, the magnet does not shift in the axial direction due to the operation of the electric motor.

[0011]

FIG. 1 shows an embodiment of a rotor according to the present invention.
In FIG. 1, the end plates 4a, 4a of the rotor are configured such that the outer diameter portion indicated by the reference numeral 11 is depressed into the step between the magnet 2 and the yoke iron core 1 and comes into contact with the end portion of the magnet 2. . FIG. 2 shows a state before the outer diameter portions of the end plates 4a, 4a are deformed. At this time, the end plates 4a are
The metal tube 3a and the metal tube 3a have substantially the same shape. As a material for the end plate 4a, a non-magnetic material is desirable, and if a material such as brass is used, it is more preferable because the molding process is easy.

In the rotor assembled in the state shown in FIG. 2, the bent portions 10a, 10a are formed by bending the end portion of the metal tube 3a toward the inner diameter side as in the conventional case. At this time,
The bending pressing force also acts on the outer peripheral portions of the end plates 4a, 4a, so that the end plates 4a, 4a are simultaneously formed. As shown in FIG. 1, when the bent portion 10a at the end of the metal tube 3a has a slightly larger bending angle, the end plates 4a and 4a can be easily formed. With the configuration shown in FIG. 1, there is no space for the magnet 2 to shift in the axial direction, and the position of the magnet 2 is maintained by the plastic deformation of the end plate 4a and the bent portion 10a of the metal tube.

In actual assembly of the rotor, one end surface of the rotor is often used as a reference surface. In this case, the magnet 2 is assembled in a state of being in contact with one of the end plates 4a. The step between the magnet 2 and the yoke core 1 occurs only at one end of the magnet 2. Therefore, in such a case, the metal pipe 3
By bending the end portion of a, only the end plate 4a on the side having a gap with the magnet 2 is configured to have its outer diameter portion depressed so as to contact the end portion of the magnet 2. Good.

Also, the bent portions 10a, 1 of the metal tube 3a
One of 0a can be formed in advance in a pre-process of fitting the outer peripheral portion of the magnet 2. This state is shown in FIGS. 3, 4 and 5. In FIG. 3, the metal tube 3a has one bent portion 10a formed in advance by bending one end of the cylinder toward the inner diameter side by press molding or the like. This metal tube 3a is formed by bending the already formed bent portion 1
The bent portion 10a is pressed by the press from the 0a side.
The magnet 2 is press-fitted into the outer periphery of the magnet 2 from the side not formed. At this time, if necessary, the metal pipe 3a may be heated and then fitted into the metal pipe 3a. The metal tube 3a has a strong rigidity due to the presence of the bent portion 10a formed in advance, and therefore has an advantage that buckling or the like is unlikely to occur due to pressing.

If the child-bending portion 10a is formed in this way, it is possible to dispose the molding die on the inner peripheral side of the metal tube 3a without exerting pressure on the magnet 2 during molding of the folding portion 10a. Therefore, the accuracy and finished shape of the bent portion 10a can be improved. In the assembly shown in FIG. 3, since the lower side is the reference surface, the magnet 2 is in contact with the lower end plate 4a, and the step 5 with the yoke core 1 is formed on the upper side.

As shown in FIG. 3, the metal tube 3a is connected to the magnet 2
As it is press-fitted into the outer periphery of the, as shown in FIG.
The bent portion 10a of the metal tube 3a contacts the upper end plate 4a. When the metal tube 3a is further pressed and pressed, the outer diameter portion of the upper end plate 4a is pressed and dented, and is depressed into the step 5 and abuts the upper end surface of the magnet 2 as shown in FIG. After that, the rotor is completed by bending the lower end of the metal tube 3a toward the inner diameter side. In this case, the lower end plate 4
Since there is no gap between a and the magnet 2, the lower end plate 4a
It is not necessary to deform the outer diameter part of the.

In the rotor shown in FIG. 1, the metal tube 3a
When the axial end portion of the metal tube 3a is pressed toward the inner diameter side when the bent portion 10a of the magnet 2 is formed, a pressing force acts on the outer peripheral corner portion 14 (see FIG. 2) of the axial end portion of the magnet 2. To do. The magnet 2 is strong against pressure on the surface,
If pressure is concentrated on the corners, the metal tube 3a will break easily.
Bending easily causes cracks in the corner portions 14 of the magnet 2 and magnet powder accompanying the cracks. According to the manufacturing method shown in FIGS. 3 to 5, the upper bent portion 10 of the metal tube 3a is
The a can be formed without pressing the magnet 2, and since the pressing at the time of forming the lower bent portion is light, it is possible to eliminate the fear of the magnet corner portion being cracked.

Further, the rotor shown in FIG. 6 improves this problem by changing the shape of the end plate. First, as shown in FIG. 7, a tray-shaped end plate 4b is formed by bending the outer diameter portion in advance, and after mounting the end plate 4b, the tip of the bent portion 12 of the end plate 4b is covered. The bent portion 10b is formed by bending the end of the metal tube 3b toward the inner diameter side. By bending the metal tube 3b, the outer diameter portion 11b of the end plate 4b is depressed into the step between the magnet 2 and the yoke iron core 1 and abuts on the magnet 2. With this configuration, the pressing portion when bending the metal tube 3b can be separated from the magnet 2,
The pressing force applied to the magnet 2 can be reduced. Of course,
The rotor may be manufactured by combining the end plate 4b shown in FIGS. 6 and 7 with the manufacturing method shown in FIGS.

[0019]

According to the present invention, even if the interference of the outer diameter of the magnet and the inner diameter of the metal tube is small and the fixation of the magnet by the metal tube is insufficient, the electric motor is operated. The magnet does not shift in the axial direction, there is no generation of iron powder or magnet powder, and there is an effect that vibration and noise are also prevented.
The quality of the rotor can be improved.

[Brief description of drawings]

FIG. 1 is a front sectional view of a rotor showing an embodiment of the present invention.

FIG. 2 is a front cross-sectional view showing a state before bending the end portion of the metal tube in the rotor of FIG.

FIG. 3 is a front cross-sectional view illustrating an example of a step of fitting a metal tube according to the present invention.

FIG. 4 is a front cross-sectional view illustrating an example of a process of fitting a metal pipe according to the present invention.

5 is a front cross-sectional view showing a state in which the steps shown in FIGS. 3 and 4 have been completed.

FIG. 6 is a front sectional view of a rotor showing another embodiment of the present invention.

7 is a front cross-sectional view showing a state before bending the end portion of the metal tube in the rotor of FIG.

FIG. 8 is a plan sectional view of a rotor showing a conventional example.

FIG. 9 is a front sectional view of a conventional rotor.

[Explanation of symbols]

 1 yoke iron core 2 magnets 3, 3a, 3b metal tube 4, 4a, 4b end plate 5 step 6 shaft hole 9 clamp pin 10, 10a, 10b bent part of metal tube 12 bent part of outer diameter part of end plate

Claims (2)

[Claims] 1. A yoke iron core having an axial hole, a magnet mounted on an outer peripheral portion of the yoke iron core, a metal tube fitted on an outer peripheral portion of the magnet, and an end covering an axial end portion of the magnet. In a magnet rotor including a plate, the magnet is mounted such that its axial length is shorter than the length of the yoke iron core, and the end is bent by bending the end of the metal tube toward the inner diameter side. A magnet rotor characterized in that an outer diameter portion of a plate is depressed into a step between the magnet and the yoke iron core and brought into contact with the magnet. 2. The end plate is mounted by bending its outer diameter portion to form a tray shape, and the end portion of the metal pipe is bent so as to cover the tip of the bent portion of the outer diameter portion of the end plate. The magnet rotor according to claim 1, wherein: