JPS626864Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to the structure of a moving coil type linear motor for moving an object to an arbitrary position within a preset range.

Conventionally, there is a linear motor disclosed in Japanese Unexamined Patent Publication No. 55-83453 as a linear motor that obtains a long motor stroke, and FIG. 1A shows its configuration, and FIG. shows. In the figure, a moving coil type linear motor has a flat plate shape and is magnetized in the thickness direction, and a plurality of permanent motors are arranged alternately (in the longitudinal direction as shown in the figure) so that the magnetization directions are opposite to each other. two sets of parallel flat yokes 2 holding the magnet pieces 1A, 1B and the permanent magnet pieces 1A, 1B on one side by adhesive;
It is composed of a flat center yoke 3 placed facing the permanent magnets 1A, 1B, and side yokes 4 fixing the yoke 2 and the center yoke 3 at both ends, and includes the permanent magnet pieces 1A, 1B and the center yoke. 3, a magnetic circuit capable of generating a uniform magnetic flux density in the gap 5 between the permanent magnet pieces 1A and 1B, and a magnetic circuit that can move within the gap 5 in a direction perpendicular to the magnetic flux, and a coil bobbin 6 with almost all of the permanent magnet pieces 1A and 1B. A movable coil 8 having two winding portions 7A and 7B each having half the winding width, holds the movable coil 8, and can slide horizontally using a guide roller 9 guided by a groove provided on the yoke 2. It is composed of a slider 10.

In such a moving coil type linear motor, the magnetomotive force generated by the drive current of the moving coil 8 acts on the magnetic circuit gap, affecting the flow of magnetic flux in the gap 5, and as a result, the movable force in the gap 5 is The magnetic flux density distribution within the air gap 5 varied depending on the position of the coil 8 and the direction of the current flowing through the movable coil, resulting in a deviation in the generated force. This deviation also differs depending on the drive current value, and becomes larger as the current value becomes higher.
Therefore, in today's world where high-speed positioning is required, it is absolutely necessary to increase the drive current value, and for this reason, the deviation in the generated force depending on the drive direction has become too large to be ignored. When such a motor is connected to a control circuit and used for positioning operation,
If a deviation occurs from the positioning position due to a disturbance, the magnitude of the restoring force varies depending on the direction of the disturbance and the positioning position, making it difficult to obtain stable control operations and to perform accurate control operations with high precision. This had the disadvantage that the control system was complicated.

The magnetic flux flowing through the air gap 5 of the magnetic circuit is a constant magnetic flux Bm that is constantly supplied by the permanent magnet pieces 1A and 1B of the magnetic circuit, and a magnetomotive force generated by the current when a current is applied to the moving coil 8. is the sum of the magnetic flux Bc flowing due to Examining the magnetic flux density distribution caused by the magnetic fluxes Bm and Bc in the air gap 5, the magnetic flux density distribution due to Bm shows a constant distribution over the entire width of the air gap 5, but the magnetic flux density distribution due to Bc shows a constant distribution within the air gap 5. The distribution state differs depending on the position of the moving coil 8 and the direction of the current flowing through the moving coil 8. Therefore, the air gap magnetic flux density distribution state generated as the sum of Bm and Bc differs depending on the position of the moving coil 8 in the air gap 5 and the direction of the current flowing through the moving coil 8, and as a result, the winding portion of the moving coil 8 is interlinked. The amount of magnetic flux generated also differs depending on the above conditions.

This deviation in the generated force due to the position of the moving coil 8 in the air gap 5 and the direction of the current flowing through the moving coil 8 is an essential problem in the configuration of the magnetic circuit, and this deviation can be reduced to zero. It was impossible.

The purpose of the present invention is to focus on the fact that the motor acceleration/deceleration time in a motor positioning control system is generally around 10ms to 20ms, and to temporarily delay the occurrence of deviations in the generated force. The aim is to minimize that influence as much as possible.

In order to achieve the above object, the present invention combines a wire made of a material with high magnetic permeability such as iron on the center yoke 3 and a wire made of a conductor such as copper or aluminum having a lower resistivity than iron. The magnetic flux generated by the current applied to the moving coil 8 is transiently canceled by the magnetic flux caused by the eddy current temporarily generated in the conductor wire by electromagnetic induction, and the generated force deviation is This is to delay the change in the magnetic flux density distribution in the air gap 5 due to the current applied to the moving coil 8, which is the cause of the generation of force, and to compensate for the transient force generated.

The present invention will be explained below with reference to the drawings.

FIG. 2A shows only the magnetic circuit portion of an embodiment of the present invention, and FIG. 2B shows a YY cross section of FIG. 2A. Note that the same parts as in FIG. 1 are indicated by the same symbols. An iron wire 1 of the same diameter is placed on the part facing the air gap 5 above the center yoke 3.
1 and copper wires 12 are combined in pairs on the center yoke 3 so as to be alternately lined up and adjacent to each other, and are wound perpendicularly to the longitudinal direction of the center yoke to obtain the above-mentioned effect. In Figure 2, wire rods (round wires) with a circular cross section of the same diameter are used.
It is clear that the same effect can be obtained by using wire rods with a rectangular cross section of the same dimensions (square wires) or wire rods having the same thickness and different widths (square wires).

According to the example, the deviation of the generated force reached a steady state about 20ms after the current was applied, but by performing the above compensation, the change in the magnetic flux was suppressed for 10ms to 20ms after the current was applied, and the deviation reached a steady state after 50ms to 80ms. The deviation of the generated force has reached a steady state.

Therefore, during the acceleration/deceleration time of the motor mentioned above, the movable coil 8 is almost never subject to changes in the magnetic flux density in the air gap 5 due to the current applied to the movable coil 8, and always receives a constant generated force.

In this way, the present invention combines a wire made of a good conductor such as copper or aluminum with a lower specific resistance than iron and a wire made of a magnetic material with high magnetic permeability such as iron on the center yoke in the part facing the air gap. By winding the coil, it is possible to delay the occurrence of deviations in the generated force caused by the current applied to the moving coil, and to improve the transient characteristics of the motor. At the same time, as is widely known in the past, it is possible to cancel the change in magnetic flux caused by the current applied to the moving coil by the magnetic flux generated by the eddy current generated on the surface of the conductor around the moving coil.
It also lowers the inductance of the moving coil, and as a result, the electrical time constant of the moving coil decreases, and when this motor is connected to a control system to perform control operations, faster and more stable control operations can be obtained. made it possible.

In addition, the present invention allows the gap length to increase by the thickness of the conductor layer, unlike when the conductor layer is uniformly placed on the center yoke, and the magnetic circuit does not become larger, and the center yoke is made of almost only iron. It is possible to obtain the same compensation effect as well as obtain the obtained air gap magnetic flux density. Moreover, the processing method is only winding work, which is extremely easy, and requires many additional work steps such as uniformly winding the conductor around the center yoke, or machining grooves on the center yoke and winding the conductor. A motor with good characteristics can be realized without any machining and without a significant increase in manufacturing costs.

Therefore, according to the present invention, no matter what position the motor is in during its stroke, it receives a constant generated force during the acceleration/deceleration time of the motor, and even when connected to a control circuit to perform positioning operations, stable operation is always achieved. I do.

Modifications can be made without departing from the spirit of the present invention, and the above description does not limit the scope of the present invention.

[Brief explanation of the drawing]

Figure 1A is a diagram showing the configuration of a conventional moving coil type linear motor, and Figure 1B is a diagram showing the configuration of a conventional moving coil type linear motor.
2A is a diagram showing the magnetic circuit configuration of the moving coil type linear motor of the present invention, and FIG. 2B is a YY sectional view of FIG. 2A. In the figure, 1A and 1B are permanent magnets, 2 is a yoke, 3 is a center yoke, 4 is a side yoke, and 5 is a
is a gap, 6 is a coil bobbin, 7A, 7B are coil winding parts, 8 is a moving coil, 9 is a guide roller, 1
0 is a slider, 11 is a wire made of a material with high magnetic permeability, and 12 is a winding made of a conductor with low specific resistance.

Claims (1)

[Scope of utility model registration request] A yoke having permanent magnet pieces on one side that are magnetized in the thickness direction and arranged alternately in the longitudinal direction so that each magnetization direction is different, a center yoke arranged opposite to the permanent magnet pieces, and the yoke and the center. A magnetic circuit consisting of a side yoke that holds a yoke and generates magnetic flux in the air gap between the permanent magnet piece and the center yoke, and a magnetic circuit that can move within the air gap in a direction perpendicular to the magnetic flux and that is mounted on a coil bobbin. In a moving coil type linear motor configured by a moving coil having two winding portions whose winding width is approximately half of the width of one piece,
A pair of wire rods made of a material with high magnetic permeability and a wire rod made of a conductor with low specific resistance are arranged in pairs so as to be arranged alternately on the center yoke 3 in a portion facing the air gap above the center yoke, and A moving coil linear motor characterized by having a winding perpendicular to the longitudinal direction of a yoke.