JPH02142332A - Electrical machinery and apparatus - Google Patents

Abstract

PURPOSE:To prevent temperature rise of a permanent magnet in an electrical machinery such as a linear motor by providing a low thermal conduction layer on the surface of the permanent magnet. CONSTITUTION:Mover 12 of a linear motor 10 is arranged movably along a guide through a predetermined gap with respect to a stator 11. Three-phase winding 121 being subjected to the field of a permanent magnet 111 is provided with three hollow coils arranged with pitch 5/3 times of the pole pitch of the permanent magnet 111. A low thermal conduction medium, i.e., a low thermal conduction layer 13, is provided on the surface of the permanent magnet 111 of the stator 11. The low thermal conduction layer 13 is applied with epoxy resin coating. By such arrangement, heat radiated from a three-phase winding 121 toward the stator 12 is shielded by the low thermal conduction layer 13, and thereby temperature rise of the permanent magnet due to increase of coil current can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to electrical equipment including permanent magnets, such as electric motors and generators.

<Conventional technology> When trying to design a small, high-speed motor,
It is common practice to increase the motor thrust by increasing the coil current. That is, the thrust of the motor is: F=B-i・■・SF F: Motor thrust (N) B: Magnetic flux density of permanent magnet (wb) i: Coil effective conductor length (m) I: Number of coil turns (T) Since there is a relationship between S: coil current (A), it is possible to obtain a large motor thrust simply by increasing the coil current without making any design changes to the motor side.

<Problems to be Solved by the Invention> However, in the case of the above conventional example, if the coil current is increased, the heat generation of the coil will correspondingly increase and the temperature of the permanent magnet will also rise, and as a result, the coil This has the disadvantage that the motor thrust cannot be increased as designed in proportion to the increased current. In other words, as the heat generation of the coil increases, the temperature of the permanent magnet facing the coil will also rise, but as the temperature of the permanent magnet increases, its magnetic properties will decrease compared to the state before the coil current increased. (See FIG. 4) In practice, the motor is designed taking into account the reduction in the magnetic properties of the permanent magnet, that is, the magnetic flux density, due to the increase in coil current.

On the other hand, if the design of the permanent magnet is changed to one with better magnetic properties, it is possible to obtain the motor thrust as designed, but there is a problem in that the cost increases accordingly. In addition, electric devices with permanent magnets, including but not limited to rotary motors, have the disadvantage that the magnetic flux density of permanent magnets decreases as the coil current increases.
It can also be a major obstacle when designing electrical equipment such as generators and near motors.

The present invention was devised in view of the above circumstances, and an object of the present invention is to provide an improved electrical device that prevents the temperature of the permanent magnet from rising even when the coil generates heat.

Means for Solving the Problems The electrical equipment according to the present invention is a motor, a generator, or other equipment that includes a permanent magnet, and a low heat conductive layer is provided on the surface of the permanent magnet.

<Operation> The heat emitted from the coil is shielded by a low thermal conductivity layer provided on the surface of the permanent magnet.

<Example> Hereinafter, an electric device according to the present invention will be described using a linear motor as an example. FIG. 1 is a side view showing the schematic structure of the beam near motor. FIGS. 2 and 3 are schematic diagrams of three-phase windings and permanent magnets for explaining modified examples of the low thermal conductivity layer.

As shown in FIG. 1, the linear motor 10 includes a stator yoke 1
It consists of a stator 11 with a plurality of permanent magnets 111 alternately magnetized on the top surface of the stator 12, and a mover 12 with a three-phase winding 121 fixed on the bottom surface of the mover yoke 122. By energizing the three-phase winding 121 (corresponding to a coil) in three phases by the near motor control circuit, the movable element 1
2 are alternately driven onto the upper surface of the stator 11. To explain in more detail, the mover 12 is
A guide (not shown) allows the stator 11 to move freely to a predetermined gap length. Also, permanent magnet 1
The three-phase winding 121 that is influenced by the magnetic field from the permanent magnet 11 includes three air-core coils that are arranged with a pitch that is 573 times the magnetic pole pitch of the permanent magnet 111. Further, on the surface of the permanent magnet 111 of the stator 11, a low thermally conductive layer 13, which is a low thermally conductive inclusion, is provided. This low thermal conductivity layer 13 is formed by coating with epoxy resin or thermally spraying ceramic, and is formed by coating the three-phase winding 1 with
It is designed to shield the conductive heat emitted from 21.

As a modification of the low thermal conductivity layer 13, as shown in FIG. 2, the surface of the permanent magnet 111 may be mirror-finished. That is, the surface of the permanent magnet 111 is finished into a mirror surface by grinding or by vapor deposition of a metal such as aluminum. According to this modification, radiant heat from the three-phase winding 121 can be shielded. In addition, as another modification, as shown in FIG. 3, the low thermal conductivity layer 13 according to the above-described modification may be formed on the surface of the low thermal conductivity layer 13 according to this embodiment. In such a modification, the three-phase winding 1
Both conductive heat and radiant heat from 21 can be shielded, and high heat shielding efficiency can be obtained.

However, even with the low thermal conductivity layer 13 according to this embodiment, the radiant heat from the three-phase winding 121 can be shielded to a certain extent by making the epoxy resin white or applying a pale white paint. .

As described above, in the near motor, even if the coil current flowing through the three-phase winding 121 is set to a large value in order to increase the motor thrust, the heat emitted from the three-phase winding 121 to the stator side has a low thermal conductivity. Since the permanent magnet 111 is shielded by the layer 13, the temperature rise of the permanent magnet 111 is suppressed. In other words, even if the coil current increases, there is no temperature change in the permanent magnet 111, so the magnetic flux density of the permanent magnet 111, which is one of the factors that determines the motor thrust, does not decrease, and as a result, the increase in coil current This means that the motor thrust can be expected to increase commensurately. Moreover, in addition to increasing the coil current, the motor thrust can be increased by simply adding a new low heat conduction layer 13 on the surface of the permanent magnet 111, which makes it possible to increase the motor thrust. This is of great significance in developing near motors.

Note that the electrical equipment according to the present invention is applicable not only to the above-described near motor but also to rotary motors such as DC machines, generators, etc., and in such cases, power conversion efficiency can be increased.

<Effects of the Invention> As described above, in the case of the electric device according to the present invention, the heat emitted from the coil is shielded by the low thermal conductivity layer provided on the surface of the permanent magnet, so the coil current is This means that it is possible to suppress the temperature rise of the permanent magnet due to the increase in the thickness of the coil.Furthermore, other than increasing the coil current, the above merits can be obtained by simply changing the design by adding a new low thermal conductivity layer. This has great significance in developing low-cost, high-performance electrical equipment.

[Brief explanation of the drawing]

1 to 3 are diagrams for explaining an embodiment of the electrical equipment according to the present invention, in which FIG. 1 is a side view showing a schematic configuration of a near motor, and FIGS. 2 and 3 are views thereof. is a schematic diagram of a three-phase winding and a permanent magnet for explaining a modification of the low thermal conductivity layer. FIG. 4 is a graph of a B-H curve showing the magnetic characteristics of a permanent magnet. IO・ 11 ・ 111・ 12 ・ 121・ 13 ・ ・Linear motor・Stator・Permanent magnet・Mover・Three-phase winding・Low thermal conductivity layer

Claims (1)

[Claims] (1) An electric device including a motor, a generator, or other permanent magnet, characterized in that a low thermal conductivity layer is provided on the surface of the permanent magnet.