JPH0564413A - Linear actuator - Google Patents

Abstract

PURPOSE:To make an apparatus high in thrust and excellent in stroke linearity by equipping a stator composed of a pair of magnets facing to a pair of linear parts and a driving means for moving a moving coil in a range where one side linear parts and one side magnets face to each other. CONSTITUTION:When anticlockwise current is supplied from a driver 5 to respective moving coils 31, 32, electromagnetic force is applied to respective moving coils 31, 32 from a magnetic field formed by magnets 11-14 and 21-24 so that a movable element 3 moves in the right-hand direction. When respective linear parts 31a, 31b and 32a, 32b move to the right ends of the magnets 11-14 which the linear parts respectively face to, the movable element 3 comes into contact with a stopper 6 to stop moving before each linear part enters the region of the next magnet. Then, when the direction of power application to respective moving coils 31, 32 is reversed, the movable element 3 moves in the left-hand direction to the starting position to stop. Thus, an actuator can be made high in thrust and excellent in stroke linearity and it is possible to control the force constant of the actuator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear actuator for driving a writing instrument such as a pen used in an automatic drafting machine in a direction perpendicular to the plane of the drawing.

[0002]

2. Description of the Related Art An automatic drafting machine or the like is provided with a writing tool such as a pen which is movable in parallel with a paper surface, and is configured to draw a drawing or the like on the paper surface by driving the writing tool along a predetermined locus. .. By the way, since the writing tool cannot always draw the desired drawing because it was always in contact with the paper surface, a linear actuator is provided which drives the writing material in the direction perpendicular to the paper surface at a desired timing and causes the writing tool to contact the paper surface only when necessary. There is.

As such a conventional linear actuator, for example, the one described in Japanese Utility Model Laid-Open No. 3-40876 is known. This one is provided with two upper and lower fixed magnets that sandwich a cylindrical center yoke, and an outer yoke that faces the outer peripheral surface of the center yoke, and is axially movable in the space between the center yoke and the outer yoke. A so-called voice coil type linear actuator in which various movable coils are arranged is known.

[0004]

In the above-mentioned conventional linear actuator, as the moving coil moves, the portion of the moving coil facing the center yoke decreases.
There is a problem that so-called stroke linearity deteriorates. However, even if the moving coil moves, in order to prevent the portion facing the center yoke from decreasing, the axial length of the center yoke should be extended or the axial length of the moving coil should be shortened. Good. However, in either case, since the magnetic flux density acting on the moving coil is reduced, the thrust is reduced, and both cannot be appropriate measures.

In view of the above problems, it is an object of the present invention to provide a linear actuator having high thrust and excellent stroke linearity.

[0006]

In order to achieve the above object, the present invention has a pair of linear portions held in parallel with each other at a predetermined interval, and moves in a direction in which the linear portions are arranged in parallel. A movable coil, a stator that is provided in parallel along the moving direction of the movable coil at the same pitch as the pitch of the linear portions, and that includes a pair of magnets facing each of the pair of linear portions; It is characterized in that it is provided with a drive means for moving the movable coil within a range in which one of the straight portions and one of the magnets face each other by supplying a direct current to the magnet.

In this case, it is preferable that at least two sets of movable coils and stators are provided and each movable coil can be separately controlled by the driving means. Further, it is preferable that the phase difference between the linear portions arranged in parallel is 180 °.

[0008]

According to the first aspect of the invention, since the linear portion of the movable coil crosses the uniform magnetic field formed by one magnet within the movable range of the movable element, the moving position of the movable element can be changed. The thrust acting on the mover does not change regardless. At the same time, since the movable coil can be arranged close to the plane of the magnet, forces other than the thrust direction can be suppressed and a large magnetic flux density can be obtained, resulting in high thrust.

According to the second aspect of the invention, the output of such a linear actuator having excellent stroke linearity can be adjusted by changing the operating state of each coil.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A linear actuator according to an embodiment of the present invention will be described with reference to FIGS. Figure 1
FIG. 2 is a structural view showing the structure of a linear actuator, and FIG. 2 is a cross sectional view thereof.

As shown in both figures, reference numeral 1 is a first magnet row, and the respective magnets 11 to 14 of the first magnet row are arranged in a state in which N poles and S poles are sequentially staggered from the left side in the figures. It is set up. Further, below the first magnet row 1, a second magnet row 2 is arranged facing the first magnet row 1 with a space therebetween. The second magnets 2 are arranged symmetrically with respect to the first magnet row 1. However, each magnet 21 to 24 of the second magnet 2
Are arranged side by side so as to be different from the polarities of the magnets 11 to 14 of the first magnet row 1 facing each other. Between the first magnet row 1 and the second magnet 2 is a moving coil 31.
The mover 3 having 2 has two guide rails 33 and 34.
The magnets 11 to 14 are held by the magnets 11 to 14 so as to be movable in parallel. The movable coils 31 and 32 are provided with linear portions 31a and 31b and 32a and 32b, respectively, which are perpendicular to the moving direction, and the distance between the linear portions 31a and 31b and 3
The distance between 2a and 32b is the same as the pitch of the magnets 11 to 14 arranged side by side. Therefore, in the starting position shown in FIG.
The straight portions 31a and 31b and 32a and 32b are magnets 1, respectively.
It will face the position near the left end of each of 1 to 14.

In this state, when the driving device 5 supplies the counterclockwise electric currents in FIG. 1 to the movable coils 31 and 32, the movable coils 31 and 32 move the magnets 11 and 32.
The movable element 3 moves to the right in FIG. 1 under the action of the electromagnetic force from the magnetic fields formed by 14 to 21 and 21 to 24. Then, the straight portions 31a, 31b and 32a
When 32b moves to the right end of each of the facing magnets 11 to 14, the mover 3 stops moving by coming into contact with the stopper 6 before the linear portion enters the area of the next magnet. And
If the direction of energization to the movable coils 31 and 32 is reversed, the mover 3 moves to the left, moves to the starting position shown in FIG. 1, and stops. As described above, since the strength of the magnetic field acting on each of the linear portions 31a, 31b and 32a, 32b is uniform within the moving range of the mover 3, the electromagnetic force acting on each of the moving coils 31, 32 is generated by the mover 3. It has a constant size regardless of movement, and therefore excellent characteristics of stroke linearity can be obtained.

Further, the thrust can be adjusted to half by energizing one of the movable coils 31 and 32 as compared with the case of energizing both of the movable coils 31 and 32, and the number of turns of the movable coils 31 and 32 can be further reduced. It is possible to adjust the thrust force more precisely by making them different or the applied current different, and it is possible to easily change the force constant of the actuator.

The mover 3 is made of synthetic resin or aluminum to reduce the weight, and the moveable coils 31 and 32 are integrally cast when the mover 3 is molded, or the mover 3 is provided with an external coil shape. The coil is embedded in the hole and adhered to the mover 3 so that the coil does not protrude from the upper and lower surfaces of the mover 3. Further, the number of moving coils is not limited to two, and a moving coil may be added if the mounting space permits, and further, for example, a light reflection type non-contact type position sensor is attached to the mover 3 and desired. When the mover 3 moves to the position, the direction of energization may be reversed, and the mover 3 may be stopped, moved in reverse, or subjected to a minute position servo.

[0015]

As is apparent from the above description, the present invention suppresses pulsation of thrust by suppressing forces other than the thrust acting on the moving coil regardless of the movement of the moving coil, thus achieving high thrust and stroke. Excellent linearity,
A linear actuator capable of adjusting the force constant of the actuator can be provided.

[Brief description of drawings]

FIG. 1 is a structural diagram showing a structure of a linear actuator according to an embodiment of the present invention.

2 is a cross-sectional view taken along the horizontal direction of FIG.

[Explanation of symbols]

 1 ... 1st magnet row 2 ... 2nd magnet row 3 ... mover 5 ... drive device 6 ... stopper

Claims (3)

[Claims] 1. A movable coil having a pair of linear portions held in parallel with each other at a predetermined interval and movable in the parallel direction of the linear portions, and along the moving direction of the movable coil. And a stator formed of a pair of magnets arranged in parallel at the same pitch as the linear portions and facing each of the pair of linear portions, and one linear portion by supplying a direct current to the movable coil. A linear actuator comprising: a driving unit that moves the movable coil within a range in which the magnet and one of the magnets face each other. 2. The linear actuator according to claim 1, wherein at least two sets of the movable coil and the stator are provided, and each movable coil can be separately controlled by the driving means. 3. The phase difference between the linear portions arranged in parallel is 18
It is 0 degree, The linear actuator of Claim 2 characterized by the above-mentioned.