JP2000058319A - Actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuator the linearity of which is improved. SOLUTION: A needle 26 is arranged in a yoke 1 on which coils 22 and 24 are mounted. The needle 26 includes a permanent magnet 28, magnetic pole pieces 30 and 32 fixed to the both main faces of the permanent magnet 28, and supporting shaft 34 penetrating the permanent magnet 28 and the magnetic pole pieces 30 and 32. The yoke 12 is provided with an extended part 60 formed, so as to extend to a region interposed by the coil 22 and the magnetic pole piece 30, and an extended part 60 formed so as to extend to a region interposed by the coil 24 and the magnetic pole piece 32. Thus, the existence of the extended part 60 is realized so that a magnetic force can act on the needle 26, even if the needle 26 is displaced in a relatively wide range, and the fluctuations of magnetic flux density in the magnetic circuit can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator, and more particularly, to a linear actuator used in an anti-vibration device such as an active engine mount for reducing vibration of an engine transmitted to a body of a vehicle such as an automobile.

[0002]

2. Description of the Related Art An example of this kind of prior art is disclosed in Japanese Unexamined Patent Publication No.
It is disclosed in Japanese Patent Publication No. 51020 and is configured as shown in FIG.

In a conventional electromagnetic actuator 1 shown in FIG. 5, a first coil 2 and a second coil 3
When a current in one direction flows through the first coil 2
And the repulsive force from the second coil acts, and the mover 4 moves in the direction of the first coil 2 (upward in the figure). On the other hand, when a current in the opposite direction is applied to the first coil 2 and the second coil 3, the repulsive force from the first coil 2 and the attraction in the direction of the second coil 3 are applied to the mover 4. The force is applied, and the mover 4 moves in the direction of the second coil 3 (downward in the figure). In this way, by switching the direction of the current flowing through the first coil 2 and the second coil 3, the mover 4 reciprocates on the support shaft 5, and the vibration generated on the support shaft 5 is reduced.

[0004]

However, in this prior art, if the mover 4 is displaced by a certain degree or more, a sufficient magnetic force is not exerted on the mover 4 and the thrust generated in the mover 4 is reduced. Since the displacement greatly changes due to the displacement of No. 4, there is a problem that linearity is not good.

[0005] Therefore, a main object of the present invention is to provide an actuator with improved linearity.

[0006]

According to a first aspect of the present invention, there is provided an actuator having a hollow cylindrical yoke, a coil mounted on the yoke, and an axial magnet provided in the yoke. An actuator comprising a movable element including a permanent magnet formed and a pole piece formed on both end faces of the permanent magnet, and a support shaft penetrating the permanent magnet and the pole piece, wherein the yoke is an area sandwiched between the coil and the pole piece. Has an extension extending to

According to a second aspect of the present invention, in the actuator according to the first aspect, the yoke includes an outer peripheral portion of the yoke and a laminate of plate members formed inside the outer peripheral portion of the yoke.

In the actuator according to the first aspect, since the yoke has an extended portion extending to a region sandwiched between the coil and the pole piece, the magnetic flux distribution is wide, and even if the mover is displaced over a relatively wide range. Magnetic force (attraction or repulsion) is applied to the mover. Also, due to the presence of the extension, the gap dimension between the mover and the yoke does not change much even if the mover is displaced, and the magnetic circuit formed by the yoke serving as the electromagnet, the permanent magnet, and the magnetic pole piece. Fluctuations in the magnetic flux density are suppressed, and fluctuations in the magnetic force exerted on the mover are also suppressed. Therefore, even when the mover is displaced in a relatively wide range, a thrust with relatively little change acts on the mover, and the linearity is improved.

In the actuator according to the second aspect, the plurality of plate-like members and the coils are inserted and laminated in a predetermined order inside the outer peripheral portion of the yoke, and the longitudinal sectional shape is substantially E.
Since a complicated yoke having a letter shape can be easily obtained and a predetermined coil can be mounted on the yoke, manufacture of the actuator is facilitated.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

Referring to FIG. 1, an actuator 10 according to an embodiment of the present invention includes a hollow cylindrical yoke 12 having a substantially E-shaped longitudinal section. The yoke 12 is made of, for example, iron or the like, and has a hollow cylindrical yoke outer peripheral portion 14.
And a yoke intermediate portion 16, a yoke lower end portion 18, and a yoke upper end portion 20 formed in the yoke outer peripheral portion 14, respectively. The yoke intermediate portion 16 is formed by laminating plate members 16a to 16e, the yoke lower end portion 18 is formed by laminating plate members 18a to 18c, and the yoke upper end portion 20 is formed by laminating plate members 20a to 20c. Plate members 16a to 16e, 18a to 18
c, 20a to 20c are hollow disk-shaped members, respectively, and are plate-shaped members 16b, 16c, 16d, 18a, 18
b, 20b, and 20c are the same members, and the plate members 16a, 16e, 18c, and 20a are the same members.

A hollow cylindrical coil 22 is mounted between the yoke intermediate portion 16 and the yoke lower end portion 18. Similarly, a hollow cylindrical coil 24 is mounted between the yoke intermediate portion 16 and the yoke upper end portion 20. Is attached. The coils 22 and 24
Is applied so that a magnetic pole of the same polarity is generated in the yoke intermediate portion 16.

A mover 26 is arranged in the yoke 12. The mover 26 includes a disk-shaped permanent magnet 28 magnetized in the axial direction, magnetic pole pieces 30 and 32 fixed to both main surfaces of the permanent magnet 28, and a permanent magnet 28, a magnetic pole piece 30,
32 and a support shaft 34 penetrating therethrough. The permanent magnet 28
For example, it is constituted by a neodymium magnet. Here, the upper surface is magnetized to the N pole and the lower surface is magnetized to the S pole. Permanent magnet 28
The pole pieces 30 and 32 are fixed to the support shaft 34 by washers 36 and 38 abutting on one main surfaces of the pole pieces 30 and 32, respectively. At this time, washer 3
6 and 38 are fitted into grooves (not shown) formed in the circumferential direction of the support shaft 34. The support shaft 34 has a hollow cylindrical linear bearing 40 and 4 at a position slightly closer to the end than the position where the washers 36 and 38 are attached.
2 are respectively held by hollow disk-shaped holders 44 and 46 made of, for example, aluminum or the like. At this time, in the normal state, the support shaft 3 is set so that the pole pieces 30 and 32 face the coils 22 and 24, respectively.
4 is held, and the support shaft 34 is a linear bearing 4
It is slidable to 0 and 42.

The lower surface of the holder 44 and the support shaft 34
The diaphragms 48 and 50 are located near the lower end of the
Is attached, and the outer cover 52 is fitted to the diaphragms 48 and 50. Similarly, diaphragms 54 and 56 are attached to the upper surface of the holder 46 and a part of the support shaft 34 from the position where the linear bearing 42 is disposed to a little from the end, respectively, and the outer covers 58 are attached to the diaphragms 54 and 56, respectively. Are fitted. Outer cover 52
And 58 play a dust and waterproof role.

It should be noted that the plate members 16a, 1
6e, 18c and 20a have a bent extension 60 at the inner peripheral end thereof. Plate members 16a and 18c
In this embodiment, the extending portion 60 is formed so as to cover both the upper and lower ends of the inner peripheral surface of the coil 22 and extend to a region sandwiched between the coil 22 and the pole piece 30. Similarly, the plate-like members 16e and 20
In a, the extension 60 is formed so as to cover the upper and lower ends of the inner peripheral surface of the coil 24 and extend to a region sandwiched between the coil 24 and the pole piece 32. The operation will be described later.

The actuator 10 constructed as described above
The operation of will be described.

First, in a normal state, that is, when no current flows through the coils 22 and 24, the mover 26
Pole pieces 30 and 32 on coils 22 and 24 respectively
Comes to a stop at the opposing position.

The externally generated vibration is generated by the support shaft 34.
Transmitted to the actuator 10 through the coil 2
Vibration is reduced by applying a sinusoidal voltage to 2 and 24 and causing a current to flow.

That is, when current flows in one direction from the normal state to the coils 22 and 24, the direction of the magnetic flux of the permanent magnet 28 constituting the mover 26 and the direction of the magnetic flux generated by the coil 24 become the same. , The direction of the magnetic flux generated in the coil 22 is opposite. As a result, a suction force acts on the mover 26 with the yoke upper end 20 and a repulsive force acts on the mover 26 with the yoke lower end 18, so that the mover 26 moves toward the yoke upper end 20 (upward in FIG. 1). Moving.

On the other hand, when a current in the opposite direction to that described above is applied to the coils 22 and 24, the direction of the magnetic flux of the permanent magnet 28 constituting the mover 26 becomes the same as the direction of the magnetic flux generated by the coil 22. , The direction of the magnetic flux generated by the coil 24 is opposite. As a result, the mover 26 has the yoke lower end 18
1 and a repulsive force acts between the yoke upper end 20 and the mover 26 in the direction of the yoke lower end 18 (FIG. 1).
Then move down).

As described above, by switching the direction of the current flowing through the coils 22 and 24, the mover 26 moves up and down in the direction opposite to the vibration generated outside, and the vibration is reduced.

Next, the operation of the extension unit 60 will be described.
This will be described with reference to FIGS.

First, referring to FIG. 2A, when extending portions 60 are formed in the yoke intermediate portion 16, the yoke lower end portion 18 and the yoke upper end portion 20, respectively, the coils 22 and 2 are formed.
The distribution of the magnetic flux (indicated by the dotted line A1) by the yoke 12 which becomes the electromagnet when a current is passed through 4 becomes wide. In addition,
The solid line B1 indicates the magnetic flux generated by the permanent magnet 28. Therefore, as shown in FIG. 2B, even when the mover 26 is displaced in a relatively wide range in the vertical direction, magnetic force is exerted on the mover 26.

Further, due to the presence of the extension portion 60, FIG.
As shown in (b), even if the mover 26 is displaced, the yoke 1
The gap size between the permanent magnet 2 and the permanent magnet 28 of the mover 26 and the magnetic pole pieces 30 and 32 does not change so much, and the magnetic circuit formed by the yoke 12 to be an electromagnet, the permanent magnet 28 and the magnetic pole pieces 30 and 32 Of the magnetic flux density is suppressed.

Therefore, as can be seen from the graph shown in FIG. 4, when the yoke 12 having the extension 60 is used (L = 2.5 mm, L = 5.6 mm), the movable element 26 has a relatively wide range. Even when the movable member 26 is displaced, a thrust with relatively little fluctuation acts on the mover 26, the linearity is improved, and the actuator 10 excellent in the vibration proof operation is obtained. Here, L refers to the length of the extension 60 as shown in FIG.

By the way, as shown in FIG. 3A, when the yoke 12a without the extension 60 is used, the coil 22
Yoke 1 that becomes an electromagnet when current is applied to
The distribution of the magnetic flux (shown by the dotted line A2) due to 2a is concentrated in a narrow range. The solid line B2 indicates the magnetic flux generated by the permanent magnet 28. Further, for example, as shown in FIG.
6 is displaced upward, the yoke 12a and the permanent magnet 2
8, since a portion having a large gap (for example, a portion surrounded by a dashed line C) is generated between the pole pieces 30 and 32, the magnetic flux in the magnetic circuit formed by the yoke 12a, the permanent magnet 28, and the pole pieces 30 and 32 The density is reduced. Therefore, if the mover 26 is displaced by a certain degree or more, a sufficient magnetic force does not reach the mover 26.

Therefore, as can be seen from the graph shown in FIG. 4, in the case of the yoke 12a without the extension 60 (L =
(0 mm), the thrust changes abruptly in accordance with the displacement of the mover 26, and it cannot cope with a large displacement of the mover 26 that is greater than a certain level, and lacks linearity.

Further, according to the actuator 10, the plate members 18a to 18c forming the yoke lower end portion 18, the coil 22, the plate members 16a to 16e forming the yoke intermediate portion 16, and the coil 24 in the yoke outer peripheral portion 14. The yoke 12 on which the coils 22 and 24 are mounted can be easily assembled simply by inserting and laminating the plate-like members 20a to 20c constituting the yoke upper end portion 20 in this order, and thus manufacturing the actuator 10. Becomes easier. Note that the plate members 16a, 16e, 18c, and 20a are all the same components, and the plate members 16b, 16c, 16d, and 18
a, 18b, 20b, 20c are all the same parts,
Since these are easily obtained by press working, it is clear that the manufacture of the yoke 12 is further facilitated.

Further, the plate members 16a, 16e, 18
c and 20a are all the same parts, and the length L
Are all equal, the plate-like member 1 sandwiching the coil 22
The magnetic forces from 6a and 18c are equal, and similarly, the magnetic forces from plate-like members 16e and 20a sandwiching coil 24 are equal.

The present invention is not limited to an engine mount, but can be applied to any device for reducing or eliminating vibration, such as a vibration isolation table or a vehicle suspension used for a semiconductor device.

[0030]

According to the present invention, the magnetic flux distribution formed between the yoke and the mover becomes wide, and even if the mover is displaced over a relatively wide range, the magnetic force is exerted on the mover. . Also, due to the presence of the extension, the gap dimension between the mover and the yoke does not change much even if the mover is displaced, and the magnetic circuit formed by the yoke serving as the electromagnet, the permanent magnet, and the magnetic pole piece. Fluctuations in magnetic flux density are suppressed, and fluctuations in magnetic force on the mover are also suppressed. Therefore,
Even when the mover is displaced in a relatively wide range, a thrust with relatively little change acts on the mover, and the linearity is improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

FIG. 2 is an illustrative view showing one example of a magnetic flux in the embodiment of FIG. 1;

FIG. 3 is an illustrative view showing one example of a magnetic flux when a yoke having no extension is used;

FIG. 4 is a graph showing a relationship between displacement of a mover and thrust.

FIG. 5 is a sectional view showing a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Actuator 12, 12a Yoke 16 Yoke middle part 18 Yoke lower end part 20 Yoke upper end part 16a-16e, 18a-18c, 20a-20c
Plate member 22, 24 Coil 26 Mover 28 Permanent magnet 30, 32 Magnetic pole piece 34 Support shaft 60 Extension L Length of extension

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hitoshi Mikami 2-15-17 Egawa, Shimamoto-cho, Mishima-gun, Osaka Prefecture Yamazaki Works, Sumitomo Special Metals Co., Ltd. (72) Naoko Sugawara Egawa, Shimamoto-cho, Mishima-gun, Osaka 2-15-15-17 Sumitomo Special Metals Co., Ltd. Yamazaki Works F term (reference) 3J048 AC08 AD03 BE08 BE09 EA01 5E048 AA04 AB10 AC05 AD02 BA07 CA02

Claims (2)

[Claims] A hollow cylindrical yoke, a coil mounted on the yoke, a permanent magnet provided in the yoke and axially magnetized, and magnetic pole pieces formed on both end surfaces of the permanent magnet; An actuator comprising a mover including a permanent magnet and a support shaft penetrating the pole piece, wherein the yoke has an extension extending to a region sandwiched between the coil and the pole piece. 2. The yoke includes a yoke outer peripheral portion and a laminate of plate-like members formed inside the yoke outer peripheral portion.
The actuator according to claim 1.