JPS619159A - Linear motor - Google Patents

Abstract

PURPOSE:To obtain an inexpensive linear motor which does not need a sensor by disposing high magnetic permeable units on a stator having a stationary coil at a constant pitch, and disposing the movable magnets of the same pitch as the units on a movable unit. CONSTITUTION:A stationary coil 4 having a current direction in reverse directions 4a, 4b is provided in a stator 3, and a high magnetic permeable unit 5 is disposed corresponding to the coil plate of one direction 4a of the two directions 4a, 4b. A movable unit 1 is slidably placed on rails 6 oppositely to the stator 3, and a movable magnet 2 is disposed at the same pitch as the unit 5 on the surface opposed to the stator 3 of the unit 1. Thus, since the unit 5 forms a closed magnetic field, even if a current is interrupted at any position, the magnet 2 and the unit 5 can be always stopped at the opposed position.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electromagnetically driven linear motor, and particularly to one that can be driven without switching the direction of current at every fixed displacement.

[Conventional technology]

Conventionally, linear motors that utilize electromagnetic force switch the direction of current flowing through a coil every time a moving magnet is displaced.

In order to switch, the magnetic field displacement of the moving magnet is detected by a sensor such as a Hall element, and the current direction is switched based on the signal. However, according to this method, the sensor and the control circuit for switching the current become expensive.

[Problem that the invention seeks to solve]

The present invention aims to provide an inexpensive electromagnetically driven linear motor that does not require sensors or associated circuits.

[Means for solving problems]

As shown in FIG. 1, the linear motor of the present invention has one of the coils 4 (as indicated by the arrow 4a) attached to a fixed body 3 with current directions in two opposite directions (arrows 4a and 4b). side)
A high magnetic permeability material 5 is placed on the fixed body 3 so as to face the fixed body 3. A measure is taken to arrange a moving magnet 2 on the side of the moving body 1 to generate a magnetic field with the same pitch as that of the high magnetic permeability body 5.

As a result, as shown in FIG. 2 (A-A cross section in FIG. 1), the closed magnetic field 7 (dashed line arrow) of the moving magnet 2 passing through the high magnetic permeability body 5
is configured.

[Effect]

By taking such measures, even if the current direction of the coil 4 remains unchanged, the movable body 1 is driven together with the magnet 2 in the x1 direction (see FIG. 1).

In a portion of the high magnetic permeability body 5, the magnetic field generated from the magnet 2 passes through the high magnetic permeability body 5 and becomes a closed magnetic field 7, so that the magnetic flux density is high. However, the magnetic field generated from the magnet 2 does not pass through the portion of the moving body 1 where the high magnetic permeability material is not attached, so the magnetic flux density is low.

As shown in FIG. 3(a), the current direction of the coil 4 is in the depth direction 4a in areas where the magnetic flux density is high.
The coil 4 receives a driving force in the x2 direction. In the portion where the current of the coil 4 is directed toward the front direction 4b, the magnetic flux density is low, so the driving force is very small. As a result, the former driving force will prevail. Since the coil 4 is fixed, its reaction 1 drives the magnet 2 together with the moving body 1 in the x1 direction. Then, when the relative positions of the moving body 1 and the fixed body 3 are displaced and the position shown in FIG. moves by inertia, assumes the positional relationship shown in (a) again, and continues moving. Therefore, when the positional relationship shown in (b) is reached, the movement speed periodically decreases in a step-like manner. Also, no matter what timing the drive current is cut off, a back electromotive force is generated in the positional relationship (a) and the drive current stops, causing so-called coking.

When a current in the opposite direction is applied to the coil 4, the moving body l moves in the opposite direction.

The driving force F is expressed as F=B i l. However, B is the magnetic flux density, the current flowing through the coil, and B is the length of the part of the coil that faces the highly permeable material.

[Embodiment 1] FIG. 4 is a perspective view of an embodiment of a linear motor to which the present invention is applied. In the figure, the moving magnet 2 is, for example, a permanent magnet made of rare earth cobalt, and is fixed to a moving body member 1a made of a highly permeable material. Movable body member 1) The gear a is provided with comb tooth portions 1b of a fixed pitch. The moving body member 1a, the comb teeth portion 1b, and the moving magnet 2 constitute a moving body l. Highly permeable magnetic materials 5 (for example, ferrite) are arranged on the fixed body 3 with gaps spaced at the same pitch as the comb tooth portions 1b. Above the high magnetic permeability body 5, a coil 4 is fixed to the fixed body 3 and formed in a zigzag pattern. Among the zigzag components of the coil 4, the current direction is directed in the direction of the arrow 4a in the portion corresponding to the upper side of the high magnetic permeability body 5, and the current direction is directed in the direction of the arrow 4b in the gap portion. The coil 4 may be of any type, such as a zigzag wire or a zigzag pattern formed on a sheet by etching. Then, the movable member 1a is placed above the coil 4 with a small distance therebetween.
The movable body 1 is arranged so that the end surfaces of the comb tooth portions 1b are opposite to each other.
It is slidably supported by a rail 6 attached to the fixed body 3 via a non-magnetic support member 8 such as n.

[Embodiment 2] The embodiment shown in FIG. 5 is a modification of the embodiment shown in FIG. This is an example in which they are arranged in a comb shape on the movable body l to form a closed magnetic path 7.

[Embodiment 3] FIG. 6 shows another embodiment of the coil 4, and shows a perspective view of the fixed body 3 side, and is an example in which the coil 4 is made to turn n times in a zigzag pattern. Further, the coil 4 may have a substantially rectangular shape as shown in FIG. 7, or a spiral shape with n turns of a circular diameter.

FIG. 8 shows the relationship between the current direction 4a-4b of the coil 4 and the magnetic field (dashed line water) when the coil 4 is wound in multiple layers as in these embodiments.

In a motor with such a configuration, depending on the number of turns n of the coil 4,
The driving force increases.

[Embodiment 4] In the portion where the current of the coil 4 is directed toward the front direction 4b, a driving force in the opposite direction works, albeit slightly, resulting in a slight braking force.In order to further reduce such braking force. To,
In the embodiment shown in FIG. 9, the current in the coil 4 is
The part facing b is a comb tooth part 1b made of a highly permeable material through which the magnetic field passes.
The effect of the magnetic field is reduced by moving it away from the magnetic field.

〔effect〕 .

As explained above, the linear motor of the present invention does not require a sensor such as a Hall element and an accompanying circuit, and therefore is inexpensive. Furthermore, even if the timing of cutting off the drive current is slightly off, the moving body will stop at a fixed position at a constant cycle, making accurate control possible and extremely convenient when used, for example, as a drive source for intermittent feed.

[Brief explanation of drawings]

Fig. 1 is a perspective view illustrating the driving principle of a motor to which the present invention is applied, Fig. 2 is a sectional view taken along line A-A, Fig. 3 is a diagram also illustrating the driving principle, and Fig. 4 is a diagram illustrating the driving principle of the motor to which the present invention is applied. FIGS. 5 to 7 are perspective views of another embodiment of the applied motor, FIG. 8 is a drive explanatory diagram, and FIG. 9 is a partial sectional view of another embodiment. ■ is a moving object, 2 is a moving magnet, 3 is a fixed object, 4 is a coil,
4a and 4b are the current direction of the coil, 5 is a high magnetic permeability material, 7 is a closed magnetic path, and xl is the moving direction. Figure 57 Figure 6 Figure 4 Figure 7

Claims (1)

[Claims] 1. A linear motor equipped with a moving magnet having a polarity direction in a direction that intersects with the direction of movement, and a fixed coil having a current direction in two mutually opposite directions that intersect with the two directions,
A high magnetic permeability body is arranged on a fixed body facing in either of the two directions, and the moving magnet that generates a magnetic field with the same pitch as that of the high magnetic permeability body is arranged on the movable body, and the high magnetic permeability body moves the body. A linear motor characterized by forming a closed magnetic field of a magnet.