WO2015132864A1

WO2015132864A1 - Linear motor

Info

Publication number: WO2015132864A1
Application number: PCT/JP2014/055323
Authority: WO
Inventors: 高野　透
Original assignee: 株式会社安川電機
Priority date: 2014-03-03
Filing date: 2014-03-03
Publication date: 2015-09-11

Abstract

[Problem] To make it possible to hold the shaft of a linear motor at a predetermined position when the linear motor is not activated, without requiring a shaft holding mechanism such as, for example, a spring. [Solution] A linear motor (1) has a stator (10) and a mover (20) and also has: a cylindrical armature portion (12) equipped with a plurality of coils (11) provided side by side in a stroke direction of the mover (20); a field portion (22) that is equipped with permanent magnets (21) disposed facing the inner circumferential surface of the armature portion (12) and is constructed so as to move relatively with respect to the armature portion (12) in the stroke direction; and a cylindrical yoke (2) having the armature portion (12) secured on the inner circumferential surface thereof and a projection amount (d1) set from a stroke end of the field portion (22) in the stroke direction so that the magnetic attraction occurring in the direction of attracting the field portion (22) toward the center side of the armature portion (12) becomes a predetermined magnitude or more while the mover (20) is being positioned within a moving range when the armature portion (12) is not activated.

Description

Linear motor

The disclosed embodiment relates to a linear motor.

In Patent Document 1, a cylindrical yoke, a coil assembly fixed inside the yoke and a plurality of coils arranged in parallel in the axial direction, and a shaft provided inside the coil assembly so as to be relatively movable in the axial direction are disclosed. And a permanent magnet assembly having a plurality of permanent magnets arranged in parallel in the axial direction and fixed to the shaft.

JP 2013-255313 A

In the linear motor having the structure as in the above prior art, a spring or the like is used to return the shaft to the initial position when there is no current, or to prevent the shaft from dropping when there is no current when the linear motor is installed along the vertical direction. There is a case where a shaft holding mechanism is used.

The present invention has been made in view of such problems, and provides a linear motor capable of holding a shaft in a predetermined position when no power is supplied without installing a shaft holding mechanism using a spring or the like. Objective.

In order to solve the above problems, according to one aspect of the present invention, a linear motor having a stator and a mover, and having a cylindrical shape provided with a plurality of coils arranged in parallel in the stroke direction of the mover. An armature part, a field magnet part provided with a permanent magnet disposed opposite to an inner peripheral surface of the armature part, and configured to move relative to the armature part in the stroke direction; The armature portion is fixed to the inner peripheral surface, and is generated in a direction in which the field portion is pulled toward the center side of the armature portion in a state where the armature portion is positioned within the movement range of the field portion when no power is supplied to the armature portion. A linear motor having a cylindrical yoke in which an amount of protrusion of the field portion from the stroke end in the stroke direction is set so that the magnetic attraction force is equal to or greater than a predetermined magnitude is applied.

According to another aspect of the present invention, a linear motor having a stator and a mover is fixed to a cylindrical yoke and an inner peripheral surface of the yoke, and is arranged in parallel in the stroke direction of the mover. And a permanent magnet disposed opposite to the inner peripheral surface of the armature portion, and relatively moves in the stroke direction with respect to the armature portion. When the energization is not applied to the field portion configured as described above and the armature portion, the mover is moved within the moving range of the field portion by a magnetic attraction force acting between the yoke and the field portion. And a linear motor having means for holding in place.

According to the present invention, the shaft of the linear motor can be held at a predetermined position without energization without installing a shaft holding mechanism using a spring or the like.

It is a longitudinal cross-sectional view of the linear motor which concerns on embodiment. It is explanatory drawing for demonstrating the generation | occurrence | production principle of the magnetic attraction force by making a yoke edge part adjoin to the stroke edge part of a field part. It is a longitudinal section at the time of installing the linear motor concerning an embodiment in the perpendicular direction. It is a longitudinal cross-sectional view of the linear motor in the modification which the both ends of a yoke adjoin to the stroke both ends of a field part. It is a longitudinal cross-sectional view of the linear motor in the modification whose dimension of an armature part is shorter than the dimension of a field part. It is a longitudinal cross-sectional view of the linear motor in the modification in which the dimension of a field part is substantially equal to the dimension of an armature part.

Hereinafter, an embodiment will be described with reference to the drawings. In the following, for convenience of description of the configuration of the linear motor and the like, directions such as up and down, left and right are used as appropriate, but the positional relationship of each configuration of the linear motor and the like is not limited.

<Configuration of linear motor>
The configuration of the linear motor 1 according to this embodiment will be described with reference to FIG. As shown in FIG. 1, the linear motor 1 is a cylinder-type linear motor. In FIG. 1, the case where the linear motor 1 is arrange | positioned in a horizontal direction, for example, and is used in a horizontal state is shown as an example. The linear motor 1 includes a yoke 2, a stator 10, and a mover 20.

The stator 10 includes a cylindrical armature portion 12. The armature portion 12 has a plurality (9 in this example) of annular coils 11 arranged in parallel in the stroke direction (left and right direction in FIG. 1) of the mover 20. The armature portion 12 is fixed to the inner peripheral surface of the yoke 2.

The mover 20 includes a field portion 22. The field magnet portion 22 has a plurality (four in this example) of permanent magnets 21 and a magnetic member 23 arranged in parallel in the stroke direction. The permanent magnet 21 is arranged to face the inner peripheral surface of the armature portion 12 with a magnetic gap. Two adjacent permanent magnets 21 are disposed such that one of the NS magnetic poles faces the other. The magnetic member 23 is disposed between the opposing surfaces of two adjacent permanent magnets 21. A shaft 5 penetrating in the axial direction is provided at the radial center of the permanent magnet 21 and the magnetic member 23.

The shaft 5 is connected to the load-side bracket 3 and the anti-load-side bracket 4 provided at the ends of one side (right side in FIG. 1) and the other side (left side in FIG. 1) of the yoke 2 with

linear motion bearings

6 and 6. 7 (for example, a sliding bearing, a rolling bearing, a ball spline, etc.) is supported so as to be movable in the stroke direction. Thereby, the field part 22 (movable element 20) is comprised so that it may move relatively in the said stroke direction with respect to the armature part 12 (stator 10).

The yoke 2 is formed in a cylindrical shape (for example, a cylindrical shape) from a magnetic material. In this embodiment, the yoke 2 serves as the housing of the linear motor 1. However, a housing may be provided separately on the outer periphery of the yoke 2.

As shown in FIG. 1, the yoke 2 has a stroke end portion of the field portion 22 such that an end portion 2 a on one side (right side in FIG. 1) in the stroke direction is close to the stroke end portion of the field portion 22. Is formed so as to protrude slightly by a predetermined protrusion amount d1. On the other hand, the end 2b on the other side (left side in FIG. 1) of the yoke 2 in the stroke direction is formed so as to protrude from the stroke end of the field portion 22 by a predetermined protrusion amount d2. The protrusion amount d2 is set larger than the protrusion amount d1. As a result, the linear motor 1 has a configuration in which the center position Os of the stroke (armature portion 12) and the center position Oy of the yoke 2 are shifted in the stroke direction.

The “stroke end” refers to an end of a range in which the field portion 22 can move to one side and the other side in the stroke direction (hereinafter referred to as “movement range”). In the present embodiment, the moving range of the field part 22 is slightly longer than the length of the armature part 12 in the stroke direction.

The protruding amount d1 is the field portion between the yoke 2 and the field portion 22 in a state where the field portion 22 is located within the movement range (for example, the stroke end portion) when the armature portion 12 is not energized. The magnetic attraction force generated in the direction in which 22 is pulled toward the center side of the armature portion 12 (yoke 2) is set to be a predetermined magnitude or more. The predetermined size is determined so that the field portion 22 and the shaft 5 are movable with respect to the stator 10 and the like according to the frictional force between the shaft 5 and the

bearings

6 and 7.

The protrusion d2 is between the yoke 2 and the field portion 22 in a state where the field portion 22 is located at the stroke end on the other side (left side in FIG. 1) when the armature portion 12 is energized. The magnetic attraction force generated in the direction in which the field portion 22 is pulled toward the center side of the armature portion 12 (yoke 2) is set to be substantially zero (small enough to have no effect).

With the above configuration, when the power of the linear motor 1 is shut off in a state (state shown in FIG. 1) where the field portion 22 is located near the stroke end portion on the one side (right side in FIG. 1), the yoke 2 The field portion 22 is moved toward the other side in the stroke direction (left side in FIG. 1) by a magnetic attractive force acting between the shaft 5 and the field portion 22, and the shaft 5 is returned to a predetermined position (for example, an initial position). Etc. are possible. Contrary to the above, when the power of the linear motor 1 is shut off in a state where the field portion 22 is positioned near the stroke end on the other side (left side in FIG. 1), the field portion 22 is There is no magnetic attractive force that is generated in the direction in which the armature portion 12 is pulled toward the center.

<Generation principle of magnetic attraction force>
Next, the principle of generation of the magnetic attraction force by bringing the end 2a of the yoke 2 close to the stroke end of the field magnet portion 22 will be described with reference to FIG. As shown in FIG. 2, the yoke 2 has an end 2a on one side (right side in FIG. 2) in the stroke direction protruding from the stroke end on one side of the field portion 22 by a slight protrusion amount d1. When the field magnet part 22 moves to one side in the stroke direction and approaches the stroke end part, the projection amount d1 of the end part 2a of the yoke 2 is set small as described above. Leakage magnetic flux F is generated in which the magnetic flux from 21 leaks outward on one side in the stroke direction. For this reason, an imbalance in the stroke direction occurs in the magnetic circuit between the field portion 22 and the yoke 2, and the field portion 22 is moved to the center side of the armature portion 12 (of the yoke 2 due to the leakage magnetic flux F). A magnetic attractive force is generated in the direction of pulling in (which is also the center side). On the other hand, even when the field portion 22 moves to the other side in the stroke direction (left side in FIG. 2) and approaches the stroke end portion, the protrusion amount d2 is set large as described above. There is no unbalance in the stroke direction in the magnetic circuit between the yoke 2 and the yoke 2, and the magnetic attractive force is not generated.

<When linear motor is placed vertically>
FIG. 3 shows a case where the linear motor 1 of the present embodiment is used in a vertically placed state, for example, arranged in the vertical direction. In the example shown in FIG. 3, the linear motor 1 is arranged so that the stroke direction of the mover 20 is substantially the vertical direction. In this case, the yoke 2 is located below the field portion 22 at the lower end portion 2a of the yoke 2 so that the lower stroke end portion of the field portion 22 is close to the lower end portion 2a of the yoke 2. The protrusion amount d1 from the stroke end on the side is set.

The protrusion amount d1 is such that when the armature portion 12 is not energized, the field portion 22 is positioned within the movement range (for example, the lower end portion of the stroke) while the field portion 22 is positioned on the armature portion 12 (yoke 2). The magnetic attraction force generated in the direction of pulling in the center side (that is, the upper side in the vertical direction) is set so as to be a predetermined magnitude or more. The predetermined size in this case is such that the field portion 22 and the shaft 5 are positioned at predetermined positions with respect to the stator 10 and the like according to the weight of the shaft 5 and the field portion 22 and the frictional force of the

bearings

6 and 7. It is determined to be retained. The configuration other than the protrusion amount d1 of the yoke 2 is the same as the configuration shown in FIG.

With the above configuration, when the linear motor 1 is placed vertically, the power of the linear motor 1 is cut off in a state where the field portion 22 is positioned near the lower stroke end (the state shown in FIG. 3). In this case, it is possible to prevent the field portion 22 and the shaft 5 from falling due to the magnetic attractive force acting between the yoke 2 and the field portion 22.

In the above, the yoke 2 and the field portion 22 in which the projection amount d1 is set are used to move the mover 20 by the magnetic attractive force acting between the yoke 2 and the field portion 22 when the armature portion 12 is not energized. This corresponds to an example of means for holding the magnetic field portion 22 at a predetermined position within the moving range.

<Effect of embodiment>
As described above, according to the present embodiment, when the linear motor 1 is disposed, for example, in the horizontal direction, the magnetic attraction force acting between the yoke 2 and the field magnet portion 22 causes the field when no current is applied. It is possible to return the magnetic part 22 and the shaft 5 to a predetermined position (for example, an initial position). Further, when the linear motor 1 is arranged in the vertical direction, for example, the magnetic attraction force can prevent the field portion 22 and the shaft 5 from dropping when no current is applied. And since magnetic attraction force is utilized, it is not necessary to install the holding mechanism of the shaft 5 using a spring. Therefore, the shaft 5 can be held at a predetermined position when no power is supplied without increasing the size of the linear motor 1. Further, when compared with a linear motor provided with a holding mechanism using a spring or the like, there is an advantage that a spring which is a life component is not necessary, installation space can be reduced, and the motor size can be reduced.

Further, in the present embodiment, in particular, the protrusion amount d1 is set so that the one end portion 2a in the stroke direction of the yoke 2 is close to the one stroke end portion in the stroke direction of the field magnet portion 22. Thereby, when the field part 22 moves to the vicinity of the stroke end on one side, it is possible to improve the certainty that the imbalance in the stroke direction of the magnetic circuit occurs. As a result, the yoke 2 and the field part 22 can be improved. Thus, the certainty that the magnetic attractive force is generated in the direction in which the field portion 22 is pulled toward the center of the armature portion 12 (yoke 2) can be increased.

In this embodiment, particularly, when the linear motor 1 is installed so that the stroke direction is the vertical direction, the yoke 2 has a lower stroke end of the field portion 22 at the lower end of the yoke 2. The protrusion amount d1 is set so as to be close to the portion 2a. Thereby, when the field part 22 moves to the vicinity of the lower stroke end part, a magnetic attractive force can be generated so as to pull the field part 22 upward. As a result, it is possible to prevent the field portion 22 and the shaft 5 from dropping when there is no energization.

<Modification>
In addition, it is not restricted to the said embodiment, A various deformation | transformation is possible within the range which does not deviate from the meaning and technical idea. Hereinafter, such modifications will be described.

(1) When both end portions of the yoke are close to both stroke end portions of the field portion In the above embodiment, the yoke 2 has one end portion 2a in the stroke direction at one stroke end portion of the field portion 22. Although it is configured to be close to each other, both end portions of the yoke 2 may be configured to be close to stroke end portions on both sides of the field magnet portion 22. An example of the linear motor of this modification is shown in FIG. 4, the same members as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted or simplified as appropriate.

As shown in FIG. 4, in the linear motor 1 </ b> A of this modification, the yoke 2 has an end portion on the other side (left side in FIG. 4) in addition to the end portion 2 a on one side (right side in FIG. 4) in the stroke direction. 2b is also configured to be close to the stroke end of the field portion 22. That is, the yoke 2 has an end 2a on one side slightly projecting from the stroke end of the field portion 22 by a predetermined projection amount d1, and an end 2b on the other side from the stroke end of the field portion 22. It is formed so as to protrude slightly by a predetermined protrusion amount d2.

The protrusions d1 and d2 are the same as the yoke 2 and the field portion when the armature portion 12 is not energized and the field portion 22 is located within the movement range (for example, the stroke end on one side and the other side). The magnetic attraction force generated in the direction in which the field magnet portion 22 is pulled to the center side of the armature portion 12 (yoke 2) is set to be greater than or equal to a predetermined magnitude. When the magnitudes of the magnetic attraction forces on one side and the other side are made equal, the projection amounts d1 and d2 are set to be equal, and when the magnitudes of the magnetic attraction forces are made different, the projection amounts d1 and d2 are also set to be different. Is done.

According to this modification, even when the field portion 22 moves to the vicinity of either one of the stroke end portions on the one side or the other side, an unbalance in the stroke direction of the magnetic circuit is generated, and the field portion is generated by the magnetic attraction force. 22 can be pulled into the center side of the armature portion 12.

(2) When the dimension of an armature part is shorter than the dimension of a field part In the said embodiment, although the case where the length of the stroke direction of the armature part 12 was longer than the field part 22 was demonstrated as an example, a field part A configuration shorter than 22 may be used. An example of the linear motor of this modification is shown in FIG. In FIG. 5, the same members as those in FIG. 1 and the like are denoted by the same reference numerals, and description thereof will be omitted or simplified as appropriate.

As shown in FIG. 5, in the linear motor 1 </ b> B of this modification, the field magnet portion 22 includes a plurality of (4 in this example) permanent magnets 21 arranged in parallel in the stroke direction (left and right direction in FIG. 5), A plurality of (three in this example) magnetic members 23 disposed between the permanent magnets 21. The armature part 12 has a plurality (three in this example) of annular coils 11 arranged in parallel in the stroke direction. The armature portion 12 is configured to have a shorter dimension in the stroke direction than the field portion 22.

The yoke 2 is configured such that both

end portions

2a and 2b in the stroke direction are close to both stroke end portions of the field magnet portion 22. Similar to FIG. 4 described above, the protrusion amounts d1 and d2 are determined when the field portion 22 is located within the movement range (for example, the stroke end portions on one side and the other side) when the armature portion 12 is not energized. The magnetic attraction force generated between the yoke 2 and the field portion 22 in the direction in which the field portion 22 is pulled toward the center of the armature portion 12 (yoke 2) is set to a predetermined magnitude or more. .

(3) When the dimension of the field part is substantially equal to the dimension of the armature part In the above, the case where the armature part 12 and the field part 22 have different lengths in the stroke direction has been described as an example. It is good also as a structure with substantially equal. An example of the linear motor of this modification is shown in FIG. In FIG. 6, the same members as those in FIG. 1 and the like are denoted by the same reference numerals, and description thereof will be omitted or simplified as appropriate.

As shown in FIG. 6, in the linear motor 1 </ b> C of this modification, the dimension of the field part 22 in the stroke direction is substantially equal to the dimension of the armature part 12 in the stroke direction. That is, in the linear motor 1 </ b> C, the field portion 22 is reciprocated while protruding the field portion 22 from the end face of the armature portion 12 by a certain amount outward in the stroke direction. Such a linear motor 1C is suitable when a required stroke is relatively small.

According to this modification, the number of the coils 11 of the armature part 12 can be reduced as compared with the conventional general structure (structure in which the armature part is longer than the field part) to obtain the same stroke. . As a result, the overall length of the linear motor 1C can be shortened, and the motor can be reduced in size and weight. In addition, since the number of parts is reduced, the cost can be reduced.

(4) Others In the above description, the case where the magnetic field portion 22 of the linear motor is a mover and the armature portion 12 is a stator has been described. Conversely, the field portion 22 is a stator and the armature portion 12 is It may be a mover.

Note that “equal” in the above description does not have a strict meaning. In other words, “equal” means that “tolerance and error in manufacturing are allowed by design and is“ substantially equal ”.

In addition to those already described above, the methods according to the above-described embodiments and modifications may be used in appropriate combination.

In addition, although not illustrated one by one, the above-described embodiment and each modification are implemented with various modifications within a range not departing from the gist thereof.

1, 1A, 1B, 1C Linear motor 2

Yoke

2a, 2b End 10 Stator 11 Coil 12 Armature 20 Mover 21 Permanent magnet 22 Field part d1, d2 Projection amount

Claims

A linear motor having a stator and a mover,
A cylindrical armature portion including a plurality of coils arranged in parallel in the stroke direction of the mover;
A permanent magnet disposed opposite to the inner peripheral surface of the armature portion, and a field portion configured to move relative to the armature portion in the stroke direction;
The armature portion is fixed to the inner peripheral surface, and the field portion is pulled in the center side of the armature portion in a state where the armature portion is positioned within the movement range of the field portion when no power is supplied to the armature portion. A cylindrical yoke in which the amount of protrusion from the stroke end of the field portion in the stroke direction is set so that the magnetic attraction force generated is greater than or equal to a predetermined magnitude;
The linear motor characterized by having.
The yoke is
2. The linear amount according to claim 1, wherein the protruding amount is set so that one end portion in the stroke direction is close to one stroke end portion in the stroke direction of the field magnet portion. motor.
The linear motor is
It is installed so that the stroke direction is the vertical direction,
The yoke is
3. The linear motor according to claim 2, wherein the protrusion amount is set so that a lower stroke end portion of the field magnet portion is adjacent to a lower end portion of the yoke.
The yoke is
The protrusion amount is set so that the other end portion in the stroke direction is close to the other stroke end portion in the stroke direction of the field magnet portion. A linear motor as set forth in claim 1.
The field part is
5. The linear motor according to claim 1, wherein a dimension in the stroke direction is equal to a dimension in the stroke direction of the armature portion.