JPH1070873A - Linear motor - Google Patents

Abstract

(57) [Problem] To provide a linear motor having improved motor efficiency by increasing the lamination coefficient of an outer core and an inner core. SOLUTION: In a linear motor including an outer core, an inner core, an inner shaft, a permanent magnet, and a coil wound on the core, a plurality of outer coils each having a coil wound thereon and an inner surface formed of a flat surface. A core, provided inside the outer core, an inner core whose outer surface is formed of a plurality of planes corresponding to the inner surface of the outer core, provided between the outer core and the inner core, the outer core and the inner core, A plurality of interacting permanent magnets are provided. Further, the outer core and the inner core are stacked perpendicularly to the direction in which the coil passes. Accordingly, the present invention increases the lamination coefficient of the outer core and the inner core and reduces iron loss, thereby improving efficiency. Further, since the distance between the inner surface of the outer core and the outer surface of the inner core is constant, the motor can exert a constant thrust.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a linear motor,
In particular, the present invention relates to a linear motor in which an outer surface of an inner core and an inner surface of an outer core are formed by a square plane.

[0002]

2. Description of the Related Art All electromagnetic type electromechanical transducers for converting mechanical energy into electrical energy and vice versa have the purpose of converting as much energy as possible. That is, the differences between electric machines are in their practicality and relative efficiency.

[0003] In order to optimize the efficiency and practicality of such electric machines, various variants are considered and exploited.

For example, the efficiency of an electric machine that converts electric energy into mechanical energy or vice versa is determined by the ratio of the output mechanical energy to the input electric energy or the ratio of the electric energy to the mechanical energy. The important factor that determines this is the core loss generated from the core. Iron loss includes hysteresis loss due to a change in magnetic flux density in the core and loss due to eddy current. Therefore, in order to improve the efficiency of an electric machine, it is important to design so that iron loss does not occur so much.

[0005] Against this background, various attempts and many studies have been made to improve the efficiency of electric machines.

Recently, a great deal of research and development has also been done on linear motors, primarily related to structure and material, and thereby efficiency.

[0007] The applications of linear motors are diverse, but differ depending on the type and structure.

In a system for driving a reciprocating compressor, a linear motor is used to improve the efficiency of the compressor. FIG. 6 shows a structure of a conventional general linear motor used for a compressor or the like.

[0009] As shown in FIG.
Reference numeral 0 denotes an outer core 12 having a coil (not shown) wound on an outer surface thereof, and an inner core 14 spaced inward from the inner surface of the outer core 12 at a predetermined interval. Further, an inner shaft 16 is integrally connected to the inner core 14 at the center of the inner core 14. A vertically movable magnet 18 is provided between the outer core 12 and the inner core 14, and when current is supplied to the coil, the magnet 18 is vertically moved. This is because the magnet 18, which is a free moving body, is moved by the interaction between the magnetic flux generated by the magnet 18 and the current supplied to the coil. However, since the direction of the current input from the AC power supply to the coil changes. The magnet 18 is moved up and down by reversing the direction of the force in accordance with the current input direction.

However, such a conventional linear motor 10
The outer core 12 has an annular horizontal section, and the inner core 14 is connected to the inner shaft 16 to form a circle. Therefore, since the circumference of the outer diameter is larger than the circumference of the inner diameter of each of the cores 12 and 14, a gap is formed outside each of the cores 12 and 14 as shown in FIG. If there is a gap in the core as described above, the lamination coefficient becomes low and the flow of magnetic flux is not smooth, so that the loss increases.

Further, it is difficult to assemble the cores so that the cross section of each core is circular, and therefore, the interval between the outer core 12 and the inner core 14 is not uniform. If the interval between the outer core 12 and the inner core 14 is not uniform, the linear motion of the permanent magnet 18 is affected,
The motor 10 cannot generate a constant thrust. Further, since the permanent magnet 18 of the moving body is also formed in an annular cross section, it is difficult to process the permanent magnet 18 and the loss of material increases. Therefore, the permanent magnet 18 used in the motor 10
Processing costs and prices increase.

That is, the above-mentioned problems of the conventional linear motor are not desirable, and not only cause a reduction in efficiency, but also prevent the motor from maintaining a stable output. In addition, as the price of the permanent magnet increases, the price of the motor also increases. Therefore, improvement of this problem is required.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a linear motor having improved efficiency by increasing the lamination coefficient of the outer core and the inner core. To provide.

It is another object of the present invention to provide a linear motor having good linearity of motion by keeping a constant distance between the inner surface of the outer core and the outer surface of the inner core.

Still another object of the present invention is to provide an inexpensive linear motor by facilitating assembling of a core and machining of a magnet as a moving body and reducing loss of material.

[0016]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a linear motor including an outer core, an inner core, an inner shaft, a permanent magnet, and a coil wound on the core. A plurality of outer cores each of which is wound with a coil and whose inner surface is formed of a plane, and an inner core which is provided inside the outer core and whose outer surface is formed of a plurality of planes corresponding to the inner surface of the outer core. , A plurality of permanent magnets provided between the outer core and the inner core and interacting with the outer core and the inner core to move linearly.

Further, the inner surface of the outer core and the outer surface of the inner core are square.

[0018] The outer core and the inner core are characterized in that a layer constituting the core is vertically stacked with a coil wound around the outer core.

Further, the magnet of the linear moving member is formed of a rectangular parallelepiped.

Further, the outer core and the inner core,
Each of the permanent magnets comprises four members, and each of the members maintains an angle of 90 degrees with respect to the axis.

Further, the inner core is formed by connecting four members, and the both ends of each of the members are provided with grooves and projections to be connected. When the members are attached, the horizontal cross section of the inner core has a closed curve. It is characterized by doing.

Further, the outer core and the inner core around which the coil is wound, and the permanent magnet of the linear moving member are each composed of two members, and each member is symmetric with respect to the inner shaft. And

[0023]

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIGS. 1, 2 and 3, the structure of the linear motor 20 according to the present invention will be described in detail. As shown, the linear motor 20 of the present invention is formed of four members, each of which has an outer core 21 at an angle of 90 degrees with respect to the axis, and is spaced inward from the outer core 21 at a predetermined interval. , An inner core 22 joined by four members corresponding to the outer core, and a coil 2 wound around the outer core
3 and four permanent magnets 24 moving up and down between the outer core 21 and the inner core 22.

As described above, the members of the outer core 21, the inner core 22, and the permanent magnet 24 maintain an angle of 90 degrees with each other with respect to the inner shaft, thereby canceling out the influence of the surrounding members. Make a smooth exercise. In this structure, the straightness of movement is also improved.

According to the present invention, the inner surface of the outer core 21 and the outer surface of the inner core 22 are formed in a quadrangular plane, so that the linear cross section of the present invention is smaller than that of a conventional linear motor having a circular horizontal section. It becomes easier to manufacture the motor core.
Manufacturing the inner or outer surface of the core into a flat surface has a simple manufacturing process as compared to manufacturing the inner or outer surface of the core to have a circular shape or a constant curvature,
This is because relatively high accuracy can be expected and there is little technical difficulty.

Since the outer surface 26 of the inner core and the inner surface 25 of the outer core are formed as flat surfaces, the distance between the inner surface of the outer core and the outer surface of the inner core becomes constant, so that the thrust of the motor is increased. Is kept constant, and the straightness of the exercise is improved.

The layers forming the core in the outer core 21 are stacked in the direction in which the coil 23 passes, that is, perpendicular to the direction of the current, and the layers forming the core also in the inner core 22 are stacked in the same direction as the outer core 21. You. As described above, the inner surface of the outer core and the outer surface of the inner core form a plane, and the core laminated perpendicularly to the direction of current has a higher lamination coefficient than the conventional cores 12 and 14 having annular cross sections, A conventional annular core 1 for smoothing the flow of magnetic flux
By reducing the iron loss as compared with 2, 14, the efficiency of the motor is increased.

The outer core 21 is composed of four members whose inner surfaces 25 are plane.
A groove 27 opened inward is formed in the middle part of 5 so that the coil 23 is wound.

As shown in FIG. 4, the inner core 22 prevents a gap from being formed on the outer peripheral surface thereof by connecting four members in a rectangular shape, but has grooves 28a at both ends of each member. Protrusions 28b are formed alternately to connect adjacent members. As described above, since the horizontal cross section of the inner core 22 is formed as a closed curve, leakage of magnetic flux is prevented.

The linearly movable permanent magnet 24 is shown in FIG.
As shown in FIG. The permanent magnet 24 made of a rectangular parallelepiped is easier to process than the permanent magnet 18 having an annular cross section due to its structural characteristics, has relatively high accuracy, and can save material. Thus, the permanent magnet 24 made of a rectangular parallelepiped has high accuracy, and a constant thrust can be exerted because the distance between the outer core 21 and the inner core 22 is constant, and smooth linear motion can be performed.

FIG. 5 is a plan view of a linear motor 30 according to an embodiment of the present invention.
The inner core 33, the outer core 35, and the permanent magnet 37, which is a linear moving member, are provided symmetrically with respect to. 39 is a coil wound around the outer core 35.

The operation of the thus constructed linear motor according to the present invention and the effects thereof will be described as follows.

First, when an AC power is applied to the motor, a current flows through the coil 23 wound around the outer core 21, thereby causing a magnetic flux to flow through a magnetic circuit including the outer core 21 and the inner core 22. At this time, the magnetic flux is applied to the outer core 21.
Crossing between the inner side surface 25 of the inner core 22 and the outer side surface 26 of the inner core 22, the magnetic flux induced by the coil 23 interacts with the magnetic flux emitted from the permanent magnet 24 to raise and lower the permanent magnet 24 as a moving body. Let it. The direction of movement is determined by Fleming's left-hand rule, which causes the permanent magnet 24 to move up and down. The force moving along the reciprocating path is F = Bil according to Faraday's law. F is the force, B is the magnetic flux density of the permanent magnet, i is the current flowing through the coil, and l is the length of the coil.

The movement of the permanent magnet will be described in more detail.

In the case of an AC power supply, the direction of the current changes at a constant cycle, so that the direction of movement of the permanent magnet 24 changes.
That is, since the direction of the magnetic flux emitted from the permanent magnet 24 is constant, the direction of movement of the permanent magnet 24 changes according to Fleming's left-hand rule as the direction of the current changes. In the case of an AC power supply, the amount of current also changes with time at a constant period, and thus the movement speed of the permanent magnet 24 changes. That is, since the amount of magnetic flux emitted from the permanent magnet 24 is constant, the moving force of the permanent magnet 24 changes according to the change in the amount of current. Since the motion acceleration of the permanent magnet 24 is proportional to this force, the motion speed changes accordingly. Therefore, the reciprocating motion of the permanent magnet 24 is performed by changing the moving direction and the force in this way.

[0037]

As described above, the linear motor according to the present invention can easily assemble the inner core and the outer core, and can shorten the assembling time. In addition, each core is formed such that the inner side surface of the outer core and the outer side surface of the inner core are formed in a plane, and are stacked vertically with the coil passing through the outer core, thereby increasing the stacking coefficient of the inner core and the outer core. Therefore, the efficiency of the motor can be improved by reducing the iron loss by smoothing the flow of the magnetic flux in each core. Since the distance between the inner surface of the outer core and the outer surface of the inner core is constant, the thrust of the motor is also constant.

Further, in the linear motor according to the present invention, since the influencing magnet, which is a moving body, is formed of a rectangular parallelepiped, machining costs and material costs can be reduced as compared with a permanent magnet having a conventional linear motor having an annular cross section.

[Brief description of the drawings]

FIG. 1 is a horizontal sectional view of a linear motor according to the present invention.

FIG. 2 is an exploded perspective view of a linear motor according to the present invention.

FIG. 3 is a sectional view taken along line IV-IV of FIG. 2;

FIG. 4 is an exploded perspective view of an inner core according to the present invention.

FIG. 5 is a horizontal sectional view of a linear motor according to an embodiment of the present invention.

FIG. 6 is a horizontal sectional view of a conventional general linear motor.

[Explanation of symbols]

 20, 30 Linear motor 21, 35 Outer core 22, 33 Inner core 24, 37 Permanent magnet 25 Inner surface 26 Outer surface 31 Inner shaft

Claims (7)

[Claims] 1. A linear motor including an outer core, an inner core, an inner shaft, a permanent magnet, and a coil wound on the core. An outer core, an inner core provided inside the outer core, an outer surface of the inner core including a plurality of planes corresponding to an inner surface of the outer core, and an inner core provided between the outer core and the inner core; A linear motor, comprising: a plurality of permanent magnets that move linearly by interacting with an outer core and the inner core. 2. The linear motor according to claim 1, wherein an inner surface of the outer core and an outer surface of the inner core are formed in a quadrangle. 3. The linear motor according to claim 1, wherein the outer core and the inner core are formed by laminating a core layer vertically with a coil wound around the outer core. 4. The linear motor according to claim 1, wherein the magnet of the linear moving member has a rectangular parallelepiped shape. 5. The apparatus according to claim 2, wherein the outer core, the inner core, and the permanent magnet each include four members, and each member has an angle of 90 degrees with respect to an axis. Linear motor. 6. The inner core comprises a combination of four members, and a groove and a projection are provided at both ends of the respective members, and the horizontal cross section of the inner core has a closed curve by attaching the members. 6. The linear motor according to claim 5, wherein the linear motor is used. 7. The permanent magnet of the outer core and the inner core on which the coil is wound, and the permanent magnet of the linear moving member, each member being symmetric with respect to the inner shaft. The linear motor according to claim 2, wherein