JP2001349371A - Magnetic circuit structure and gap control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide magnetic passage structure where the change ratio of a suction force is set to a value higher than a change in a gap by devising formation of a magnetic circuit. SOLUTION: A magnet assembly 11 in which permanent magnets 14A and 14B are incorporated and a target 2 being a body to which magnetism is attracted are situated opposite to each other. By forming a magnetic circuit having the magnetic passage, running through a gap G, between the magnet assembly 11 and the target 2 by a magnetic force generated by the permanent magnets 14A and 14B, an attraction force is generated between the magnet assembly 11 and the target 2. In this case, the magnetic passage 18 is formed such that magnetic lines of force in the single magnetic circuit 17 make at least two round flows through the gaps G1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic circuit structure applicable to a magnetic levitation device, an active suspension and the like.
And a gap control device using the magnetic circuit structure.

[0002]

2. Description of the Related Art Since an operating mechanism using magnetic force or magnetic attraction force can be driven precisely without contact, it is expected to be applied to a manufacturing apparatus or a precision driving apparatus requiring a clean environment such as a semiconductor and a liquid crystal. Have been. In particular, an operation mechanism using a permanent magnet does not generate heat unlike an electromagnet, and thus has a wide application range, and is actually applied to, for example, a magnetic levitation device and a guide device for a linear motor.

In these devices, a magnet and a magnetic material are used.
Or control the distance (gap) between magnets at high speed,
Must be performed with high resolution and high rigidity. for that reason,
For example, in a magnetic levitation device or the like, a piezoelectric element is often used to manage the gap in order to ensure high responsiveness.

FIG. 9 shows an example of a conventional magnetic circuit structure used for a magnetic positioning device (active suspension).

In the illustrated magnetic circuit structure, 1 is a magnet assembly (one of two members),
2 is a magnetically attracted body (positioned body) composed of a magnetic material
The target (the other member) 3 is a piezoelectric element (driving means).

As shown in a perspective view in FIG. 10, a magnet assembly 1 has a permanent magnet 4 and both magnetic poles (N pole,
(South pole), and has a U-shaped cross section as a whole.

The target 2 is constantly receiving an urging force (separation force) directed upward in the figure by urging means (separation means viewed from the magnet assembly 1 side) not shown.

The piezoelectric element 3 includes a magnet assembly 1
Is finely driven to adjust the size of the gap G between the magnet assembly 1 and the target 2.

In this magnetic circuit structure, the two U-shaped end surfaces 1T and 1T of the magnet assembly 1 are arranged to face the target 2 with a gap G interposed therebetween. As a result, a magnetic circuit 7 having a magnetic path 8 passing through the gap G is formed between the magnet assembly 1 and the target 2 by the magnetic force generated by the permanent magnet 4, and an attractive force is generated between the magnet assembly 1 and the target 2. It has become.

When the size of the gap G changes, the intensity of the magnetic field lines in the magnetic path 8 of the magnetic circuit 7 changes. Utilizing this characteristic, when the magnitude of the gap G is detected and the current for driving the piezoelectric element 3 is feedback-controlled so as to keep it constant, as a result, the attractive force acting between the magnet assembly 1 and the target 2 is reduced. The target 2 is controlled to be constant, and the target 2 can be suctioned and maintained at a predetermined position.

Note that, when the upper and lower portions of FIGS. 9 and 10 are turned upside down, the target 2 can function as a magnetic levitation device that attracts and floats (against gravity).

[0012]

By the way, the piezoelectric element 3
Since the displacement of the driving unit 3A is small, the stroke for controlling the gap G cannot be large, and therefore, there is a problem that the change in the attractive force between the magnet assembly 1 and the target 2 cannot be increased.

In general, by stacking a plurality of piezoelectric elements, the stroke can be increased to some extent, but there is a problem that the piezoelectric elements are increased in size. In order to increase the stroke, attempts have been made to increase the amount of displacement by applying a mechanical lever.However, the mechanism becomes complicated, the rigidity decreases, and the inertial mass increases.
New responsiveness and hunting problems will occur.

According to the present invention, by taking into account the above circumstances, the formation of the magnetic path is devised so that the rate of change of the attraction force with respect to the change of the gap can be increased, thereby avoiding the complexity and size of the entire apparatus. Another object of the present invention is to provide a magnetic circuit structure capable of realizing high rigidity and high stability.

[0015]

According to a first aspect of the present invention, there is provided a magnetic circuit having two members opposed to each other with a gap therebetween, and a magnetic circuit having a magnetic path passing through the gap between the two members. In the magnetic circuit structure that generates a predetermined attractive force between the two members, the magnetic circuit is formed such that a magnetic path in the magnetic circuit reciprocates at least two times in a gap between the two members. This has solved the above-mentioned problem.

Here, in order to form the magnetic circuit, the two members may include only one of them with a magnet, the other may be composed of a simple magnetic body, or both may include a magnet. It can also be configured.

In the magnetic circuit structure according to the present invention, the magnetic force lines in one magnetic circuit reciprocate at least twice in the gap. Therefore, the attractive force itself is reduced by the number of times of passing through the gap. , The amount of change of the suction force with respect to the fluctuation of the pressure can be increased. That is, a large suction force change can be obtained with a small gap change amount. In other words, when performing control to change the suction force using the gap change as an index, a high gain response to the same gap change is possible, and controllability can be improved. Therefore, for example, even if only a small gap change amount can be given by the piezoelectric element, a variation amount of the attraction force related to the magnetic levitation control and the like can be made large, and the gap control and the like can be made reliable or easy. be able to.

It should be noted that a reduction in the overall attractive force can be dealt with by increasing the magnetic force of the permanent magnet to be incorporated. Further, since there is no mechanical gain amplifying mechanism such as a lever, problems such as a decrease in responsiveness due to an increase in the inertial mass of the system and occurrence of hunting do not occur.

Here, "to reciprocate the gap between two members more than once" means that the magnetic path does not necessarily have to reciprocate more than once in a single gap. May have a plurality of gaps through which the holes pass. In essence, "the gap (single or multiple) that exists between the two members results in a magnetic path of 2
A single magnetic circuit is formed so as to reciprocate and pass more than once ".

As a specific configuration, for example, at least one of the two members is magnetically shielded from each other by interposing a non-magnetic material therebetween.
The magnetic circuit forming portion is arranged, and both end faces of the two or more magnetic path forming portions are opposed to the other member of the two members with a gap therebetween, and the magnetic circuit is generated by the magnetic circuit. A configuration may be adopted in which the magnetic path of the magnetic circuit is formed such that the lines of magnetic force pass through a path that sequentially connects the other member and both end faces of the two or more magnetic path forming portions in series. Item 2).

In this case, the distance between the portion other than the end face forming the gap and the other member and the thickness of the non-magnetic material are set so that the magnetic path does not short-circuit at a portion other than the portion opposing the gap. Etc. need to be large enough for the size of the gap.

Incidentally, the magnets may be included in all of the magnetic path forming portions (claim 3), or the magnetic path forming portions may not include the magnets (claim 4).

When magnets are included in all the magnetic path forming portions, the magnetic force of the entire magnetic circuit can be increased accordingly, and the attraction force can be increased. Also, 2
Of course, more than two magnets may be incorporated, in which case the attraction force can be further increased.

Here, “the magnet is included in the magnetic path forming portion”
What is meant by a configuration in which a magnet is embedded in a core made of a magnetic material, a configuration in which a core is coupled to one pole or both poles of a magnet, and a configuration in which one magnetic path forming portion is entirely one And the like. That is, the magnetic path forming part itself includes a configuration that functions as one magnet regardless of the presence or absence of the core.

On the other hand, when a magnetic path forming portion that does not include a magnet is provided, the magnetic path forming portion only functions as a magnetic material that passes the magnetic force lines of the magnets included in the other magnetic path forming portions. However, since it does not include the magnet, it can be formed more compact, and the degree of freedom of the shape can be increased, and the cost can be reduced. That is, a magnetic path forming part that does not include such a magnet is arranged in a place where a magnet cannot be incorporated in terms of shape or dimensions, and a magnetic path forming part that includes a magnet is placed in a place where there is room in terms of shape or dimensions. By arranging, the degree of freedom in designing the magnetic circuit structure can be increased.

The fifth to seventh aspects of the present invention capture the magnetic circuit structure of the present invention from the shape characteristic surface of the one member. The first magnetic path forming part and the second magnetic path forming part are each formed in a U-shape in cross section with the non-magnetic material interposed therebetween, and the three parts are laminated and integrated in this order to form a whole. The object has been solved by forming the one-sided member having a U-shaped cross section and disposing the front end surface of the U-shape to face the other-sided member with a gap therebetween.

According to a sixth aspect of the present invention, the first aspect of the present invention is further embodied. The first magnetic path forming portion, the nonmagnetic material, and the second magnetic path forming portion are sequentially reduced in size. Alternately, it is formed as a U-shaped ring body with a radial cross section, and the three members are fitted and laminated and integrated in this order to form a "one-side member" having a ring shape with a U-shaped cross section as a whole. It is characterized by having comprised.

The present invention also includes a ring-shaped member in which the center hole of one side member is closed by any member and the whole is formed in a disk shape.

A seventh aspect of the present invention embodies the invention of the fifth aspect by another method, wherein the first magnetic path forming portion, the nonmagnetic material, and the second magnetic path forming portion are Are formed in the same size in a U-shaped cross-section, and the three members are arranged side by side in this order, and are laminated and integrated to constitute the one-sided member having a U-shaped cross-section as a whole. And

In this magnetic circuit structure, an electromagnet can be used as a magnet for forming a magnetic circuit. However, if a permanent magnet is used, the magnet is not affected by heat generation.
Gap control can be performed accurately. Further, since the present invention can be applied to a place where the influence of heat generation is disliked, the range of application is further expanded.

According to an eighth aspect of the present invention, the present invention is applied to a gap control device for two members, and the magnetic circuit structure according to any one of the first to seventh aspects is provided, and the gap between the two members is controlled. By controlling the magnetic attraction force between the two members to a predetermined value by feedback-driving one of the two members (relative to the partner member) using the size of the gap as an index, There is provided driving means capable of maintaining the size constant.

As the driving means, for example, a piezoelectric element can be used, and by changing the size of the gap by this driving means, the suction force acting between the two members can be changed. At that time, as described above, since the magnetic path in the magnetic circuit makes two or more round trips in the gap,
It is possible to obtain a change in the suction force that is sensitive to a change in the stroke of the gap adjustment, thereby improving the controllability.

[0033]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a magnetic circuit structure according to a first embodiment of the present invention, and FIG. 2 is a perspective view of a magnet assembly constituting the magnetic circuit structure.

This magnetic circuit structure is composed of the permanent magnets 14A, 1
4B, a magnet assembly (one member) 11, a target (the other member) 2 as a magnetically attracted body made of a magnetic material, and a piezoelectric element (driving means) 3
And

The magnet assembly 11 has a side cross-sectional shape formed in a U-shape.
Are disposed to face the target 2 with the gap G1 interposed therebetween.

The target 2 is constantly receiving an urging force (attraction force) directed upward in the figure by an urging means (or suction means) not shown.

The piezoelectric element 3 includes a magnet assembly 1
Is finely driven to adjust the size of the gap G1 between the magnet assembly 1 and the target 2.

In this magnetic circuit structure, as described above, both the U-shaped end surfaces 1 of the magnet assembly 1 are formed.
T and 1T are arranged to face the target 2 with the gap G1 interposed therebetween. As a result, one magnetic circuit 17 having a magnetic path 18 passing through the gap G1 is formed between the magnet assembly 11 and the target 2 by the magnetic force generated by the permanent magnets 14A and 14B. A suction force is generated between the two.

The magnet assembly 11 is fixed to the driving section 3A of the piezoelectric element 3.

As shown in FIG. 2, the magnet assembly 11 includes first and second two magnetic path forming bodies (magnetic path forming parts) 16A and 16B, and both magnetic path forming bodies sandwiched therebetween. And a spacer 19 made of a non-magnetic material for magnetically shielding between 16A and 16B.

Each of the magnetic path forming bodies 16A and 16B is composed of cores 15A and 15B made of a magnetic material and permanent magnets 14A and 14B.
B, and cores 15A and 15B are coupled to both poles (N pole and S pole) of the permanent magnets 14A and 14B.

The first magnetic path forming member 16A, the spacer 19, and the second magnetic path forming member 16B are formed in a U-shaped cross section whose size is sequentially reduced. The magnet assembly 11 having a U-shaped cross section is formed by laminating and integrating in a telescopic manner.

That is, the end faces 16A of the pair of magnetic path forming bodies 16A and 16B are arranged on the end face 11T of the magnet assembly 11 with the end face 19T of the spacer 19 interposed therebetween.
T and 16BT face the target 2 with the gap G1 interposed therebetween.

The polarities of the permanent magnets 14A and 14B are first,
The second magnetic path forming bodies 16A and 16B are set in opposite directions. As a result, the magnetic path 18 of the magnetic circuit 17 is formed so as to reciprocate twice in the gap G1. That is, the lines of magnetic force generated by the magnetic circuit 17 are both end faces 16AT of the target 2 and the magnetic path forming bodies 16A, 16B.
So as to follow a path that connects 16BT in series
A magnetic path 18 of the magnetic circuit 17 is formed.

The size of the recess 11D of the magnet assembly 11 and the thickness of the spacer 19 are set to be sufficiently large with respect to the gap G1 between the target 2 and the magnet assembly 11 so as not to cause a short circuit in the magnetic path. I have.

Next, the operation will be described.

In general, the attractive force of the magnet is determined by the magnetic resistance on the magnetic path. Further, the magnetic resistance of air is sufficiently higher than the magnetic resistance of a magnetic material. Therefore, when there is an air gap (hereinafter simply referred to as "gap") on the magnetic path, it can be said that the generated attraction force is substantially determined by the size of the air gap.

In the conventional magnetic circuit structure shown in FIGS. 9 and 10, there are only two gaps G1 in the magnetic circuit 7, and the magnetic path 8 has the magnet assembly 1 and the target 2
Only one reciprocation between the magnetic circuit 17 and the magnetic circuit structure of the present embodiment described above.
And the magnetic path 18 is the magnet assembly 1
Reciprocate between target 1 and target 2 twice. That is, the magnetic path 18
Passes through the gap G1 four times while making a round of the magnetic circuit 17.

For this reason, when the size of the gap G1 between the magnet assembly 11 and the target 2 is changed by the piezoelectric element 3, the magnetic resistance in the gap G1 changes about twice as compared with the conventional method. Therefore, even with the piezoelectric element 3 having the same driving stroke, a large change in magnetic resistance can be generated, and a large change in attractive force can be obtained between the magnet assembly 11 and the target 2. As a result, gap control (attraction force control) with high gain and high response can be realized.

Next, a second embodiment of the present invention will be described.

FIG. 3 is a sectional view showing the structure of the magnet assembly 21 in the magnetic circuit structure according to the second embodiment.

The magnet assembly 21 is formed in a ring shape by rotating the U-shaped cross section of the magnet assembly 11 of the first embodiment about the central axis L. That is, the ring-shaped magnet assembly 21 has a U-shaped radial cross section when viewed from the side, and an end face 21T opposed to the target 2 with the gap G2 therebetween at the center and the outer periphery, The end face 21 </ b> T is arranged to face the target 2.

A magnetic circuit 27 having a magnetic path 28 passing through the gap G2 is formed concentrically around the entire circumference between the magnet assembly 21 and the target 2, whereby the magnetic assembly 27 is attracted between the magnet assembly 21 and the target 2. Force is generated.

The magnet assembly 21 includes a first
And the second two magnetic path forming bodies (magnetic path forming parts) 26A, 2
6B and both magnetic path forming bodies 26A,
6B and a spacer 29 made of a non-magnetic material for magnetically shielding the space between 6B.

Each magnetic path forming body 26A, 26B is composed of a permanent magnet 24A, 24B and a core 25 coupled to both magnetic poles.
A, 25B. Further, the first magnetic path forming body 26A, the spacer 29, and the second magnetic path forming body 26B are formed as a ring having a U-shaped radial cross section whose size is sequentially reduced. A ring-shaped magnet assembly 21 having a U-shape in radial cross section is formed by nesting inward from the inside and laminating and integrating. Therefore, the cores 25A and 25B and the permanent magnets 24A and 24B are also formed in a ring shape by themselves.

The end face 21T of the magnet assembly 21
, The end faces 26AT, 26A of the pair of magnetic path forming bodies 26A, 26B arranged with the end face 29T of the spacer 29 interposed therebetween.
The BT faces the target 2 across the gap G2. Also, permanent magnets 24A magnetized in the radial direction,
The polarity of the first and second magnetic path forming bodies 26A, 26B
B is set in the opposite direction. Thus, also in this case, the lines of magnetic force generated by the magnetic circuit 27
And both end surfaces 26A of the magnetic path forming bodies 26A and 26B
The magnetic path 18 of the magnetic circuit 17 is formed so as to follow a path connecting the T and 26BT sequentially in series, and the magnetic path 28 of the magnetic circuit 27 makes two round trips in the gap G2. Therefore, the same function and effect as those of the first embodiment can be obtained.

Next, a third embodiment of the present invention will be described.

FIG. 4 is a sectional view showing a magnetic circuit structure according to the third embodiment, and FIG. 5 is a view taken along the line VV of FIG.

The magnet assembly 31 in the magnetic circuit structure of the present embodiment is a modification of the ring-shaped magnet assembly 21 in the second embodiment shown in FIG. That is, the magnet assembly 2 shown in FIG.
1. First magnetic path forming member 2 at the center indicated by two-dot chain line IV
The 6A portion is replaced by a cylindrical (large and strong) permanent magnet 34, and the permanent magnets (24A, 24B) at other locations are eliminated. In terms of shape, one cylindrical permanent magnet is provided at the center. It is a disk-shaped one incorporating a magnet 34. Therefore, it can be considered here that the magnet assembly 31 in this case is formed by filling the center of the ring-shaped magnet assembly into a disk shape.

The magnet assembly 31 includes a first
And the second two magnetic path forming bodies (magnetic path forming parts) 36A, 3
6B and both magnetic path forming bodies 36A, 3B sandwiched between them.
6B and a spacer 39 made of a non-magnetic material for magnetically shielding the space between 6B. Here, one magnetic path forming body 36A is
A permanent magnet 34 and a core 35 coupled to one of the magnetic poles
A. Also, the other magnetic path forming body 36B
Is composed only of a magnetic material that does not include a magnet.

In this magnetic circuit structure, the permanent magnet 3
4 generates a magnet assembly 3
Magnetic path 3 passing through gap G3 between target 1 and target 2
Thus, a magnetic force is generated between the magnet assembly 31 and the target 2.

The end face 31T of the magnet assembly 31
In the above, each of the end faces 36 of the pair of magnetic path forming bodies 36A and 36B concentrically arranged with the end face 39T of the spacer 39 interposed therebetween.
AT, 36BT is the gap G
The magnetic path 28 is formed so that the magnetic force line 38 indicated by a dotted line in the magnetic circuit 37 reciprocates twice in the gap G3.

In this case, as in the example of FIG.
Makes two reciprocations in the gap G3, so that the same operation and effect as in the first embodiment can be obtained.

In the case of the magnet assembly 31 according to the third embodiment, one cylindrical permanent magnet 34
Is simply arranged at the center of the ring, and no other permanent magnets are arranged. Therefore, the structure can be made simple, compact, and low in cost.

Also, since the columnar permanent magnet 34 is used,
Special permanent magnet 24 magnetized in the radial direction as shown in FIG.
A stronger permanent magnet can be obtained easily and inexpensively as compared with the structure using A and 24B.

Next, a fourth embodiment of the present invention will be described.

FIG. 6 is a perspective view showing a magnetic circuit structure of the fourth embodiment, and FIG. 7 is a perspective view of a magnet assembly constituting the same magnetic circuit structure.

In the case of the magnet assembly 11 of the first embodiment shown in FIG. 1, a first magnetic path forming body 16A, a spacer 19, and a second magnetic path, each of which is sequentially changed in size and formed in a U-shaped cross section, are used. Although the formed body 16B is stacked and integrated in this order from the outside to the inside, in the case of the magnet assembly 41 of the fourth embodiment, the first magnetic path forming body (magnetic path forming portion) 46A is used. And non-magnetic spacer 49
And a second magnetic path forming body (magnetic path forming portion) 46B are formed in the same size in a U-shaped cross section. An assembly 41 is formed.

Each of the magnetic path forming bodies 46A and 46B is composed of cores 45A and 45B made of a magnetic material and permanent magnets 44A and 44B.
B, and cores 45A and 45B are coupled to both poles (N pole and S pole) of the permanent magnets 44A and 44B.

The two end surfaces 41T of the magnet assembly 41 formed in a U-shaped cross section are
2 are arranged opposite to each other with a gap G4 interposed therebetween. As a result, a single magnetic circuit 47 having a magnetic path 48 passing through the gap G4 is formed between the magnet assembly 41 and the target 42 by the magnetic force generated by the permanent magnets 44A and 44B. A suction force is generated between 42.

A magnet assembly 41 having a U-shaped cross section
Of both ends 41T of the spacer 49
The respective end surfaces 46AT, 46BT of the pair of magnetic path forming bodies 46A, 46B arranged with the T interposed therebetween face the target 42 with the gap G4 interposed therebetween.

On the other hand, on the target 42 side, two magnetic path forming members 42A and 42B formed of a magnetic material, and a non-magnetic material made of a nonmagnetic material sandwiched therebetween and magnetically shielding the two magnetic path forming members 42A and 42B. And a spacer 43. The magnetic path forming bodies 42A and 42B and the spacer 43 on both sides are formed in a U-shape in side view, and the magnet assembly 41 is formed.
A concave portion 42D is provided on the surface facing the surface. The concave portion 42D is for preventing a short circuit of the magnetic path 48 of the magnetic circuit 47.

The magnetic path forming bodies 46A and 46B of the magnet assembly 41 and the magnetic path forming body 42 of the target 42
A and 42B are in a correspondence relationship in which the directions are shifted (rotated) by 90 degrees, and the two tip surfaces 41T and 41T of the magnet assembly 41 are
It faces 2A and 42B.

Further, the polarities of the permanent magnets 44A, 44B are set in opposite directions in the first and second magnetic path forming bodies 46A, 46B, so that the magnetic lines of force generated by the magnetic circuit 47 are directed to the target 42. And magnetic path forming bodies 46A, 46B
The magnetic path 4 of the magnetic circuit 47 is arranged so as to follow a path in which the two end faces 46AT and 46BT are sequentially connected in series.
8 are formed, and the magnetic path 48 of the magnetic circuit 47 reciprocates two times in the gap G4. Therefore, the same function and effect as those of the first embodiment can be obtained.

In the first to fourth embodiments, the case where the magnetic path in the magnetic circuit makes two reciprocations in the gap has been described. However, the magnetic path may be made to reciprocate more times.

In the magnetic circuit structure according to the fifth embodiment shown in FIG.
The magnetic path is configured so that the magnetic path 58 in one magnetic circuit 57 reciprocates in the gap G three times.

In the case of the fifth embodiment, the magnet assembly 51 is made up of first to third three magnetic path forming bodies (magnetic path forming parts) 56A, 56B, 56C and spacers (non-magnetic) for magnetically shielding them from each other. (Magnetic material) 59. Each magnetic path forming body 56A, 56B, 56C is
A, 55B, 55C and permanent magnets 54A, 54B, 54C
It is composed of Note that two permanent magnets 54A are arranged in series on the first magnetic path forming body 56A.

The magnet assembly 51 has a recess 5
Three end faces 51T are formed with 1D interposed therebetween, and each end face 51T is formed.
T, each end surface 56A of a pair of magnetic path forming bodies 56A, 56B, 56C arranged with the end surface 59T of the spacer 59 interposed therebetween.
T, 56BT, and 56CT face the target 2 with the gap G5 interposed therebetween.

The polarity of the permanent magnets 54A, 54B, 54C is the same as that of the outer first magnetic path forming body 56A and the inner second magnetic path forming body 56A.
The third magnetic path forming bodies 56B and 56C are set in the opposite directions, so that the magnetic path 58 indicated by a dotted line in the magnetic circuit 57 formed between the magnet assembly 51 and the target 2 forms the gap G5. A magnetic path is formed so as to reciprocate three times. That is, the first, second, and third magnetic path forming bodies 56 facing the target 2 with the gap G5 interposed therebetween.
A, 56B, 56C each end face 56AT, 56
The magnetic path 58 of the (single) magnetic circuit 47 is formed so as to follow a path connecting the BT and 56CT in series.

In this magnetic circuit structure, the permanent magnet 5
4A to 54C, a magnetic circuit 57 having the magnetic path 58 passing through the gap G5 is formed between the magnet assembly 51 and the target 2 and thereby the magnet assembly 51 and the target 2 are formed.
A suction force is generated in between.

In this case, the gap G5 is provided in the magnetic circuit 57.
And the magnetic path 58 is the magnet assembly 51
Reciprocates three times between the target and target 2. That is, the magnetic path 58
Passes through the gap G5 six times while making a round of the magnetic circuit 57, so that a gap G5 between the magnet assembly 51 and the target 2 is formed by a piezoelectric element (not shown).
When the magnitude is changed, the magnetic resistance in the magnetic circuit 57 changes about three times as compared with the conventional method. Therefore, even if the piezoelectric element has the same drive stroke, the magnetic resistance between the magnet assembly 51 and the target 2 can be reduced. Can be greatly changed.

In this example, it is not always necessary to arrange permanent magnets in all the magnetic path forming members.

In each of the above embodiments, the case where a permanent magnet is incorporated as a magnet has been described. However, an electromagnet may be arranged instead of the permanent magnet.

In the above embodiment, the targets 2, 4
Although the two sides are composed of only a magnetic material that does not include a magnet, a magnet may be incorporated in the target side so that an attractive force is generated between the magnets on both the magnet assembly side and the target side. A magnet may be incorporated only on the side. In any case, in one magnetic circuit, the polarity of the magnets is arranged so that the magnets are arranged in series, and the magnetic path is formed such that the magnetic lines of force in one magnetic circuit reciprocate twice or more in the gap. realizable.

These magnetic circuit structures can be applied to a gap control device of a magnetic levitation device or a magnetic positioning device as in the prior art. In other words, if one of the two members is feedback-driven (with respect to the counterpart member) by driving means such as a piezoelectric element using the size of each gap in these magnetic circuit structures as an index, Since the magnetic attraction force between the two members can be controlled to a predetermined value with a high gain, a gap control device that can stably maintain the size of the gap can be obtained.

[0087]

As described above, according to the present invention,
Since the magnetic path is formed between the two members so that the magnetic lines of force in one magnetic circuit reciprocate in the gap two or more times, the amount of change in the attraction force with respect to the change in the gap can be increased. Therefore, a response with a high gain is possible for the same gap change, and controllability can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a magnetic circuit structure according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a magnet assembly constituting the magnetic circuit structure of FIG. 1;

FIG. 3 is a sectional view of a magnet assembly constituting a magnetic circuit structure according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a magnetic circuit structure according to a third embodiment of the present invention.

FIG. 5 is a view taken in the direction of arrows VV in FIG. 4;

FIG. 6 is a sectional view of a magnetic circuit structure according to a fourth embodiment of the present invention.

FIG. 7 is a perspective view of a magnet assembly constituting the magnetic circuit structure of FIG. 6;

FIG. 8 is a sectional view of a magnetic circuit structure according to a fifth embodiment of the present invention.

FIG. 9 is a sectional view of a conventional magnetic circuit structure.

FIG. 10 is a perspective view of a magnet assembly constituting the magnetic circuit structure of FIG. 9;

[Explanation of symbols]

G1 to G5 Gap 2, 42 Target (the other member) 3 Piezoelectric element (drive unit) 11, 21, 31, 41, 51 Magnet assembly (one member) 11T, 21T, 31T, 41T, 51T Tip surface 14A, 14B, 24A, 24B, 34A, 34B, 4
4A, 44B, 54A, 54B, 54C ... permanent magnets 15A, 15B, 25A, 25B, 35A, 35B, 4
5A, 45B, 55A, 55B, 55C ... cores 16A, 16B, 26A, 26B, 36A, 36B, 4
6A, 46B, 56A, 56B, 56C ... magnetic path forming body (magnetic path forming section) 16AT, 16BT, 26AT, 26BT, 36AT,
36BT, 46AT, 46BT, 56AT, 56BT,
56CT end face 17, 27, 37, 47, 57 magnetic circuit 18, 28, 38, 48, 58 magnetic path 19, 29, 39, 49, 59 spacer (non-magnetic material) 19T, 29T, 39T, 49T , 59T ... End face

Claims (8)

[Claims] A magnetic circuit having a magnetic path passing through the gap is formed between the two members, and a predetermined attractive force is applied between the two members. The magnetic circuit structure to be generated, wherein the magnetic circuit is formed such that a magnetic path in the magnetic circuit reciprocates at least two times in a gap between the two members. 2. The device according to claim 1, wherein at least one of the two members is provided with two or more magnetic path forming portions that are magnetically shielded from each other by interposing a non-magnetic material therebetween. Both end surfaces of each of the two or more magnetic path forming portions are opposed to the other member of the two members with a gap therebetween, and a line of magnetic force generated by the magnetic circuit is formed between the other member and the two or more members. The magnetic circuit structure of the magnetic circuit, wherein the magnetic circuit of the magnetic circuit is formed so as to follow a path sequentially connected in series with both end surfaces of the magnetic path forming portions. 3. The magnetic circuit structure according to claim 2, wherein each of the two or more magnetic path forming portions includes a magnet. 4. The magnetic circuit structure according to claim 2, wherein at least one of the two or more magnetic path forming portions does not include a magnet in itself. 5. The magnetic path forming section according to claim 2, wherein a first magnetic path forming section and a second magnetic path forming section are interposed with the non-magnetic material interposed therebetween. The three members are formed in a U-shaped cross section, and the three members are laminated and integrated in this order to form the one-sided member having a U-shaped cross-section. A magnetic circuit structure characterized by being arranged facing each other with a gap therebetween. 6. The ring according to claim 5, wherein the first magnetic path forming portion, the non-magnetic material, and the second magnetic path forming portion are sequentially changed in size to form a U-shaped ring body with a radial cross section. A magnetic circuit structure, characterized in that the three members are fitted and laminated and integrated in this order to form the one-sided member having a ring shape with a U-shaped cross section in its entirety. 7. The device according to claim 5, wherein the first magnetic path forming portion, the non-magnetic material, and the second magnetic path forming portion are each formed in the same size and have a U-shaped cross section.
A magnetic circuit structure, wherein the three members are arranged side by side in this order and laminated and integrated to constitute the one-sided member having a U-shaped cross section as a whole. 8. A magnetic circuit structure according to claim 1, wherein said magnetic circuit structure has a gap between said two members as an index.
A driving unit that controls a magnetic attraction force between the two members to a predetermined value by feedback-driving any one of the two members, thereby maintaining a constant size of the gap. The gap control device between the two members to perform.