JP4403703B2 - Slotless permanent magnet motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a servo motor and a direct drive motor used for a drive shaft that dislikes speed ripple in the FA field such as machine tools and semiconductor manufacturing apparatuses.
[0002]
[Prior art]
A slotless permanent magnet motor having a very small cogging torque, which is the cause of the occurrence, is applied to the drive shaft that dislikes speed ripple. For example, as such a slotless permanent magnet motor, there are one disclosed in Patent Document 1 and one constituted by a winding manufacturing method disclosed in Patent Document 2 or Patent Document 3. FIG. 5 is a side sectional view of a slotless permanent magnet motor in the prior art, and FIG. 6 is an enlarged view of a portion A in FIG.
In the figure, 1 is a rotor, 2 is a rotor yoke, 3 is a permanent magnet, 4 is a shaft, 5 is a load side bearing, 6 is a counter load side bearing, 10 is a stator, 11a is a stator yoke, 12a is an air core winding, 13 is Insulating paper, 14 is a mold resin, 15 is a frame, 16a is a load side bracket, and 17 is an anti-load side bracket.
The rotor 1 includes a rotor yoke 2, a permanent magnet 3 having a plurality of magnetic poles attached to the surface of the rotor yoke 2, and a shaft 4. The rotor 1 is rotatably supported with respect to the stator 10 by a load side bearing 5 and an anti-load side bearing 6 attached to the shaft 4.
On the other hand, the stator 10 is inserted into a hollow cylindrical stator yoke 11a, an air core winding 12a disposed on the inner periphery of the stator yoke 11a, between the stator yoke 11a and the air core winding 12a, and on the inner periphery of the air core winding 12a. Insulating paper 13, air core winding 12a, insulating paper 13 and stator resin 11 integrally molded resin 14, frame 15 covering outer periphery of stator yoke 11a, load side holding load side bearing 5 and anti-load side bearing 6 The bracket 16a and the anti-load side bracket 17 are comprised. Here, as a material, the stator yoke 11a is a laminated silicon steel sheet that reduces iron loss due to an alternating magnetic field, the insulating paper 13 is a highly insulating polyamide insulating paper, the mold resin 14 is also an highly insulating epoxy resin, The frame 15 is made of aluminum having high thermal conductivity, and the load side and anti-load side brackets 16a and 17 are made of light and high-strength metal aluminum.
Further, a rotation angle sensor (not shown), for example, a high resolution optical encoder is attached to the opposite side of the stator 10.
Such a slotless permanent magnet motor generates a rotating magnetic field in the gap portion between the rotor 1 and the stator 10 by causing a current corresponding to the magnetic pole of the rotor 1 to flow through the air core winding 12a. Torque is generated in the rotor 1 by attraction and repulsion with the magnetic field created by the magnetic poles. Furthermore, since it has a slotless structure, it is characterized in that no cogging torque is generated due to a change in permeance between the stator yoke 11a and the permanent magnet 3, and the speed ripple is small.
Also, copper loss occurs in the air core winding 12a due to current flowing. Copper loss, that is, heat generated in the air-core winding 12a is radiated mainly through the stator yoke 11a and the frame 15. Therefore, the temperature rise of the air core winding 12a is determined by the thermal resistance between the air core winding 12a and the frame 15.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 58-58845 [Patent Document 2]
JP-A-60-216746 [Patent Document 3]
Japanese Patent Laid-Open No. 62-244251 [0004]
[Problems to be solved by the invention]
However, in the slotless permanent magnet motor in the prior art, the following problems may occur due to copper loss occurring in the air core winding 12a.
(1) The temperature rise of the air core winding 12a increases and the air core winding 12a burns out.
(2) Since the temperature rise of the air core winding 12a becomes large, the temperature of the permanent magnet 3 arranged via the air core winding 12a and the gap rises and is thermally demagnetized.
(3) Since the temperature rise of the air-core winding 12a increases, the temperature of the optical encoder on the anti-load side also rises, causing malfunctions and thermal damage of the integrated circuit components that are the signal processing circuit.
The present invention has been made to solve such problems, and an object of the present invention is to provide a slotless permanent magnet motor that reduces the temperature rise of the air-core winding.
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention described in claim 1 includes a hollow cylindrical stator yoke, a frame that covers the outer periphery of the stator yoke, a load-side bracket attached to both ends of the frame in the axial direction, and an anti-load side. In a slotless permanent magnet motor having a bracket, a stator having an air-core winding disposed on the inner periphery of the stator yoke, and a rotor having a permanent magnet, the load-side bracket is provided with a ring-shaped recess, and the ring-shaped recess Inserting the air core winding and the end of the stator yoke into the recess, with the outer peripheral surface of the end of the stator yoke in contact with the outer peripheral surface of the recess, and the ring-shaped recess of the load side bracket; , between the stator yoke and air wound, it is obtained by the so that provided a small air layer.
As a result, the heat generated in the air core winding can be distributed to the frame and the load side bracket via the stator yoke and released at the same time , and the temperature rise of the air core winding can be reduced.
According to a second aspect of the present invention , a good heat conductive grease is interposed in the minute air layer .
Thus, a minute air layer made to the end of the recess and air wound and the stator yoke of the load-side bracket, by filling a high thermal conductivity grease, the heat generated in the air wound, to claim 1 It is possible to escape to the load side bracket better than the described invention .
According to a third aspect of the present invention, an adhesive having high thermal conductivity is interposed in the minute air layer .
Thus, by filling with an adhesive having high thermal conductivity , the heat generated in the air-core winding can be more efficiently released to the load side bracket as in the second aspect of the invention . Furthermore, the load-side bracket whose strength has deteriorated due to the provision of the recesses can be integrally fixed to the stator yoke and the air-core winding with a good heat conductive adhesive, thereby ensuring the strength of the entire stator.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a side sectional view of a slotless permanent magnet motor according to a first embodiment of the present invention, and FIG. 2 is an enlarged view of a portion A in FIG. Hereinafter, the same reference numerals are given to the same constituent elements of the present invention as those in the prior art, the description thereof is omitted, and only different points will be described. In the figure, 11b is a stator yoke according to the present invention, 12b is an air core winding, and 16b is a load side bracket.
The present invention is fundamentally different from the prior art in that a ring-shaped recess is provided in the load side bracket 16b and the load side end portions of the stator yoke 11b and the air core winding 12b are inserted.
The stator yoke 11b and the air core winding 12b are made longer than the prior art by the amount inserted into the recess. At this time, a minute air layer is provided between the load side bracket 16b, the stator yoke 11b, and the air core winding 12b so that the air core winding 12b contacts the load side bracket 16b and does not deteriorate in insulation.
With such a configuration, the thermal resistance from the air core winding 12b to the load side bracket 16b can be extremely reduced. The heat generated in the air core winding 12b flows from the stator yoke 11b to the frame 15, and further flows to the bracket 16b. Therefore, the heat generated in the air core winding 12b can be dispersed, and the temperature rise of the air core winding 12b can be greatly reduced.
Further, the outer peripheral surface of the concave portion of the load side bracket 16b is cut so that the stator yoke 11b contacts. The air core winding 12b can be accurately positioned only by inserting the air core winding 12b integrated with the stator yoke 11b into the recess of the load side bracket 16b.
[0007]
Next, a second embodiment will be described.
FIG. 3 is an enlarged view of part A of FIG. 1 to which the second embodiment of the present invention is applied. The difference from the first embodiment is that a good heat conductive grease 18 is interposed in a minute air layer provided between the load side bracket 16b, the stator yoke 11b and the air core winding 12b.
As the good heat conductive grease 18, for example, a so-called silicone oil compound in the form of grease in which silica fine powder or the like is blended with a silicone oil base oil is used. In general, the silicone oil compound is also excellent in insulation, so that the insulation of the air core winding 12b is maintained. Here, when comparing the thermal conductivity of air and silicone oil compound, air is 0.025 W / (m · ° C), whereas silicone oil compound is about 40 times 0.92 W / (m · ° C). It is.
By interposing a good heat conductive grease in the minute air layer, the thermal resistance from the air core winding 12b to the load side bracket 16b can be further reduced. As a result, the temperature rise of the air core winding 12b can be reduced as compared with the first embodiment.
[0008]
Next, a third embodiment will be described.
FIG. 4 is an enlarged view of part A of FIG. 1 to which the third embodiment of the present invention is applied. The difference from the first and second embodiments is that a good heat conductive adhesive 19 is interposed instead of a minute air layer or good heat conductive grease between the load side bracket 16b, the stator yoke 11b and the air core winding 12b. It was made to.
As the good heat conductive adhesive 19, for example, an epoxy adhesive filled with alumina is used. In general, an alumina-filled epoxy adhesive is also excellent in insulation, so that the insulation of the air-core winding 12b is maintained.
Here, when comparing the thermal conductivity between the alumina-filled epoxy adhesive and air, the air is 0.025 W / (m · ° C.), whereas the alumina-filled epoxy adhesive is about 50 times higher. 1.15 W / (m · ° C.).
By interposing such a good heat conductive adhesive 19 in the minute air layer, the thermal resistance from the air core winding 12b to the load side bracket 16b can be reduced.
As a result, the temperature rise of the air core winding 12b can be reduced as compared with the first embodiment. Furthermore, the strength of the entire stator can be ensured by fixing the load side bracket 16b, whose strength has been deteriorated by providing the recesses, to the stator yoke 11b and the air core winding 12b integrally with the heat conductive adhesive 19. it can.
[0009]
【The invention's effect】
As described above, the present invention has the following effects.
(1) According to the first embodiment of the present invention, by inserting the air core winding and the load side end of the stator yoke into the ring-shaped recess provided in the load side bracket, The generated heat can be dispersed, and the temperature rise of the air-core winding can be reduced. As a result, it is possible to avoid the conventional problems such as burning of the air core winding, thermal demagnetization due to the temperature rise of the permanent magnet, malfunction of the integrated circuit component due to the temperature rise of the optical encoder, and heat damage. In addition, the air core winding can be accurately positioned only by inserting the air core winding integrated with the stator yoke into the concave portion of the load side bracket.
(2) According to the second embodiment of the present invention, the air-core winding is obtained by interposing a good heat conductive grease in the minute air layer between the concave portion of the load side bracket, the air-core winding and the stator yoke. And the load side bracket can further reduce the thermal resistance, and the temperature rise of the air-core winding can be reduced as compared with the first aspect.
(3) Similarly, according to the third embodiment of the present invention, the air core is obtained by interposing a good heat conductive adhesive in the minute air layer between the recess of the load side bracket, the air core winding and the stator yoke. The thermal resistance between the winding and the load side bracket can be further reduced, and the temperature rise of the air-core winding can be reduced as compared with the first embodiment. Furthermore, the strength of the entire stator can be ensured by fixing the load side bracket, whose strength has been deteriorated by providing the recesses, to the stator yoke and the air core winding with a good heat conductive adhesive.
[Brief description of the drawings]
FIG. 1 is a side sectional view of a slotless permanent magnet motor according to a first embodiment of the present invention.
FIG. 2 is an enlarged view of a main part of the slotless permanent magnet motor showing the first embodiment of the present invention.
FIG. 3 is an enlarged view of a main part of a slotless permanent magnet motor showing a second embodiment of the present invention.
FIG. 4 is an enlarged view of a main part of a slotless permanent magnet motor showing a third embodiment of the present invention.
FIG. 5 is a side sectional view of a slotless permanent magnet motor in the prior art.
FIG. 6 is an enlarged view of a main part of a slotless permanent magnet motor in the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rotor 2 Rotor yoke 3 Permanent magnet 4 Shaft 5 Load side bearing 6 Anti-load side bearing 10 Stator 11a, 11b Stator yoke 12a, 12b Air core winding 13 Insulating paper 14 Mold resin 15 Frame 16a, 16b Load side bracket 17 Anti load side bracket 18 Good thermal conductive grease 19 Good thermal conductive adhesive

Claims (3)

A hollow cylindrical stator yoke, a frame covering the outer periphery of the stator yoke, a load side bracket and an anti-load side bracket attached to both ends of the frame in the axial direction, and an air core coil disposed on the inner periphery of the stator yoke In a slotless permanent magnet motor having a stator having a rotor and a rotor having a permanent magnet,
The load-side bracket is provided with a ring-shaped recess, the air core winding and the end of the stator yoke are brought into contact with the ring-shaped recess, and the outer peripheral surface of the end of the stator yoke is brought into contact with the outer peripheral surface of the recess. And a minute air layer is provided between the ring-shaped recess of the load side bracket, the stator yoke and the air core winding . 2. The slotless permanent magnet motor according to claim 1 , wherein a good heat conductive grease is interposed in the minute air layer . 2. The slotless permanent magnet motor according to claim 1, wherein a good heat conductive adhesive is interposed in the minute air layer.

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