JPH10285898A - Linear actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear actuator in which a coil is not damaged even when it is subjected to a vibration and an impact and in which an energy loss is small. SOLUTION: An inside yoke 4 which comprises an inside coil 7 and an inside coil 8 is arranged coaxially at the inside of a cylindrical outside yoke 1 which comprises an outside coil 5 and an outside coil 6. Both end parts in the axial direction of the inside yoke 4 are supported so as to be held from both end parts in the axial direction of the outside yoke 1. An intermediate yoke 14 which comprises respective magnets 15 to 18 arranged and installed between the outside yoke 1 and the inside yoke 4 is supported by the inside yoke 4 so as to be advanced and retreated freely in the axial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear actuator which generates a linear displacement by an electromagnetic action.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a cross-sectional view showing a conventional linear actuator described in Japanese Unexamined Patent Application Publication No. H10-115,004. In the figure, the outer yoke 111 has a pair of coils 121 and 122 on its inner peripheral surface.
An inner yoke 118 disposed inside the outer yoke 111 has a pair of coils 123 and 124 on its outer peripheral surface.
It has. The intermediate yoke 119 is provided between the outer yoke 111 and the inner yoke 118 so as to be able to advance and retreat in the axial direction (b direction).
Four magnets 125 to 128 facing each other with an air gap are fixed to 21 to 124. These magnets 12
Nos. 5 to 128 are magnetized such that magnetic poles of the same polarity face each other across the intermediate yoke 119 in a direction (radial direction) orthogonal to the axial direction, and magnetic poles of different polarities face each other in the axial direction.
When each magnet is magnetized in this manner, two closed magnetic paths through which magnetic flux passes in the axial direction of the intermediate yoke 119 between the outer yoke 111 and the intermediate yoke 119 and between the inner yoke 118 and the intermediate yoke 119. a (magnetic flux loop) is formed.

[0003] Each of the above elements is mounted with a support 112 as a common support base, and the support 112 is a member having a disk portion 112a and a hollow cylindrical portion 112b. The outer yoke 111 is fixed to the outer periphery of the disk part 112a. The inner yoke 118 is fixed to the hollow cylindrical portion 112b. The intermediate yoke 11
9 is connected to an output shaft 117, and the output shaft 117 is held by a hollow cylindrical portion 112b via a pair of slide bearings 116 so as to be able to advance and retreat in the axial direction. The axial distance between the slide bearings 116 is equal to the distance between the magnets 125 (or 12).
7) and approximately equal to the axial spacing between the magnet 126 (or 128).

In the conventional linear actuator constructed as described above, when currents are supplied to the coils 121 to 124 of the outer yoke 111 and the inner yoke 118 so as to generate predetermined magnetic poles, the magnets 125 to 128
, A thrust based on Fleming's law is generated in the coils 121 to 124, and the intermediate yoke 119 causes the output shaft 117
And move in one axial direction. When a current is supplied so as to generate a magnetic pole of the opposite polarity, the output shaft 11
7 moves in the other axial direction. In this way, a linear displacement output is provided at the output shaft 117.

[0005]

In the conventional linear actuator as described above, the intermediate yoke 119 is held by holding the output shaft 117 by the hollow cylindrical portion 112b. However, this hollow cylindrical part 1
Since 12 b is a member constituting the support 112 together with the disk 112 a, the intermediate yoke 119 is consequently held by the disk 112 a of the support 112. That is, the intermediate yoke 119 is in a so-called cantilever support state in which the intermediate yoke 119 is supported only by the disk portion 112a existing on one side in the axial direction. In such a cantilever support structure, when vibration or impact is applied to the output shaft 117 from the outside, the disk portion 11
2a may be bent. When the disk portion 112a is bent, the coils 121 to 124 and the magnets 125 to 12
8 varies. In particular, the air gap between the coils 121 and 122 provided on the outer yoke 111 and the magnets 125 and 126 facing each other changes greatly, and the magnet 125 (or 126)
21 (or 122) to contact the coil 121 (or 12).
2) may be damaged. Therefore, the output shaft 117
When used in an environment where a certain level of vibration or impact is expected to be applied, the air gap is designed to be large in advance. However, if the air gap is increased, the loss of magnetic energy increases and the energy conversion efficiency decreases, so the intermediate yoke 119 and the output shaft 117
It was inevitable that the power provided to the power supply would decrease.

[0006] In view of the above-mentioned conventional problems, the present invention does not damage the coil even when subjected to vibration or impact.
It is another object of the present invention to provide a linear actuator with low energy loss.

[0007]

A linear actuator according to the present invention has a cylindrical outer yoke, an outer coil provided on an inner peripheral surface of the outer yoke, and the outer yoke connected to the outer yoke at both axial ends. An inner yoke concentrically arranged inside the outer yoke, an inner coil provided on an outer peripheral surface of the inner yoke, and a cylindrical shape arranged coaxially between the outer yoke and the inner yoke. An intermediate yoke, an output shaft connected to the intermediate yoke, and a magnet provided on the outer peripheral surface and the inner peripheral surface of the intermediate yoke so as to face the outer coil and the inner coil, respectively. A movable body supported by at least one of the outer yoke and the inner yoke so as to be able to advance and retreat in the axial direction (claim 1). In the linear actuator configured as described above,
Both ends of the inner yoke and the outer yoke are connected to each other, and the inner yoke is in a so-called double-supported support state by the outer yoke. In such a support state, even if the output shaft of the movable body receives vibration or impact, the inner yoke or the outer yoke supporting the movable body is not deformed, and as a result, the air gap between the coil and the magnet is kept constant. . Therefore, it is not necessary to set the air gap to a relatively large value, and the air gap can be set to a substantially minimum value, so that energy loss is reduced and output is increased.

In the above linear actuator, a pair of side plates are provided on both end surfaces of the outer yoke in the axial direction. The inner yoke is fixed to the pair of side plates, and the movable body penetrates the pair of side plates. (Claim 2). In the linear actuator configured as described above, the inner yoke is supported by the outer yoke at both ends by the side plate, and the output can be taken out from the movable body penetrating the side plate.

Further, in the linear actuator (claim 1), the magnets include a first magnet and a second magnet which are arranged on the outer peripheral surface of the intermediate yoke so as to be axially separated from each other, and an inner peripheral surface of the intermediate yoke. And a third magnet and a fourth magnet respectively disposed at positions corresponding to the first magnet and the second magnet.
The magnet, the third magnet and the fourth magnet, the first magnet and the third magnet, and the second magnet and the fourth magnet may be configured to have polar arrangements in which different polarities are opposed to each other ( Claim 3). In the linear actuator configured as described above, the first magnet and the third magnet constitute one magnet body together with the intermediate yoke present therebetween, and the second magnet and the fourth magnet constitute another magnet together with the intermediate yoke present therebetween. Of the magnet body. A common closed magnetic path (magnetic flux loop) formed by the pair of magnets penetrates the intermediate yoke vertically. Therefore, the magnetic flux is not limited by the thickness of the intermediate yoke. In other words, the intermediate yoke can be made as thin as possible as long as the mechanical strength can be maintained. By reducing the thickness of the intermediate yoke, the movable body is reduced in weight, and the responsiveness of the operation is improved.

In the above linear actuator (claim 1), the intermediate yoke may be formed so that at least three protruding ends are formed at both ends in the axial direction (claim 4). In the linear actuator configured as described above, the driving force can be transmitted to the output shaft while securing a predetermined strength while reducing the weight of the movable body by the minimum necessary number of projecting ends.

In the above linear actuator, the intermediate yoke has at least three projecting ends formed at both ends in the axial direction, and these projecting ends penetrate the side plate. (Claim 5). In the linear actuator configured as described above, the driving force can be transmitted to the output shaft while securing a predetermined strength while reducing the weight of the movable body by the minimum necessary number of projecting ends.

In the linear actuator (claim 3), the intermediate yoke may be made of a magnetic material over the entire length in the axial direction (claim 6). In the linear actuator configured as described above, since the intermediate yoke can be integrally formed, its manufacture is easy.

In the linear actuator (claim 4 or 5), the movable body may be provided with a rotation preventing means in the circumferential direction (claim 7). In the linear actuator configured as described above, the rotation of the movable body in the circumferential direction is preferentially prevented by the rotation preventing means. Therefore,
It is possible to prevent the protruding end of the intermediate yoke from contacting the peripheral member and increasing the sliding resistance.

In the linear actuator (claim 6), a magnet holding member may be provided on the inner peripheral surface and the outer peripheral surface of the intermediate yoke adjacent to each of the first to fourth magnets (claim 8). ). In the linear actuator configured as described above, even if the magnet attached using an adhesive or the like is separated due to the aging of the adhesive, the magnet can be prevented from falling off.

In the linear actuator (claim 1), a potentiometer may be connected to the movable body in parallel with the axial direction (claim 9). In the linear actuator configured as described above, since the movement amount of the movable body can be detected by the potentiometer, the stroke control of the movable body is facilitated.

Further, in the above linear actuator (claim 1), the movable body has a drive shaft at its axial center, and a slide bearing is provided in a section facing the drive shaft and the inner yoke. (Claim 10). In the linear actuator configured as described above,
Since the slide bearing does not protrude from the end of the inner yoke, the sliding resistance of the drive shaft can be reduced without increasing the axial dimension of the linear actuator.

Further, in the linear actuator (claim 2), the movable body has a drive shaft at an axis thereof, and a slide bearing is provided in a section opposing the drive shaft and the inner yoke. The side plate may be adjacent to one end of the first member (claim 11). In the linear actuator thus configured, the side plate plays a role of preventing the slide bearing from coming off.

In the linear actuator (claim 1), the outer coil and the inner coil may be bobbin-less rectangular coils (claim 1).
2). In the linear actuator configured as described above, the air gap can be reduced by the amount that the bobbin or the like is not used, and the output can be improved.

In the above linear actuator, the inner coil and the outer coil are single-phase wound, and each lead wire is led out through a groove formed in the inner yoke and the outer yoke. (Claim 13). In the linear actuator configured as described above, since the lead wire is hidden by the groove, the air gap can be reduced.

In the above linear actuator (claim 1), the movable body includes a flange for connecting the intermediate yoke and the output shaft, and the flange may be made of a non-magnetic material (claim). 14). In the linear actuator thus configured, the weight of the movable body can be reduced by using a lightweight metal such as aluminum. The lightness of the movable body improves the responsiveness of the operation.

[0021]

1 to 9 are drawings showing a linear actuator according to an embodiment of the present invention. FIG. 1 is a sectional view as viewed from the front side, FIG. 2 is a left side view, and FIG. 3 is a right side view. 4 is a partial sectional view taken along line IV-IV in FIG. 2, and FIG. 5 is a partial sectional view taken along line VV in FIG. Also, FIG.
9 is a drawing related to the movable body 30 in the linear actuator. In FIG. 1, substantially disk-shaped side plates 2 and 3 are attached to both axial ends of an outer yoke 1 which is a cylindrical magnetic body. The inner yoke 4 is a columnar magnetic body having a through-hole 4a formed in the center shaft portion, and is attached to the side plates 2 and 3 at both ends in the axial direction, so that the inner yoke 4 is held in a so-called double-supported state and It is arranged concentrically inside the yoke 1. On the inner peripheral surface of the outer yoke 1, a first
The coil 5 and the second coil 6 are arranged to form an outer coil, and the third coil 7 and the fourth coil 8 are similarly arranged on the outer peripheral surface of the inner yoke 2 in the axial direction. Are formed.

Each of the coils 5 to 8 is formed by winding a rectangular coil (for example, having a cross section of 0.5 mm × 5 mm) into a single layer using an adhesive varnish, without using a bobbin or the like. 1 and the outer peripheral surface of the inner yoke 4. Therefore, it is possible to reduce the air gap as much as the bobbin is not used. Lead wires 23 and 24 are drawn out from both ends of each of the coils 5 to 8. Leads 23 and 24 are
It is led out through grooves 1b and 4b formed in the inner surface of the outer yoke 1 and the outer surface of the inner yoke 4 in the axial direction. Therefore, the presence of the leads 23 and 24 does not cause an increase in the air gap.

At both ends of the through hole 4a of the inner yoke 4, slide bearings 9 of a predetermined length are mounted so as to be completely housed in the inner yoke 4 over the entire length thereof. The inner diameter of the through hole 4a at the axial center is smaller than the portion where the slide bearing 9 is mounted, and serves as a stopper for preventing the slide bearing 9 from moving to the inner side of the through hole 4a. doing. Also, the slide bearing 9
The side plates 2 and 3 adjacent to the slide bearing 9
Also serves as a stopper to prevent the shaft from being pulled out in the axial direction. The drive shaft 10 inserted in the slide bearing 9 is movable in the axial direction relative to the outer yoke 1 and the inner yoke 4.

As described above, due to the configuration in which the slide bearing 9 is completely accommodated in the inner yoke 4 over its entire length, the factor that causes the slide bearing 9 to increase the axial length of the entire linear actuator is as follows. No.
The axial distance between the pair of slide bearings 9 is wider than the axial distance between the first magnet 15 (or the third magnet 17) and the second magnet 16 (or the fourth magnet 18). Therefore, the displacement of the movable body 30 in the radial direction due to the dimensional tolerance inherent in the slide bearing 9 can be extremely reduced.

A substantially disk-shaped flange 11 (see FIG. 2) and a disk-shaped flange 12 (see FIG. 3) are attached to the drive shaft 10 at the left and right ends in the axial direction, respectively, orthogonal to the axial direction. An output shaft 13 is further coaxially attached to the drive shaft 10 at the left end in the axial direction. On the circumference of a predetermined radius (R) from the axis of the drive shaft 10, an intermediate yoke 14 made of a magnetic material is disposed coaxially with the outer yoke 1 and the inner yoke 4, and attached to the flanges 11 and 12. ing. A first magnet 15 and a second magnet 16 are disposed on the outer peripheral surface of a predetermined region in the center in the axial direction of the intermediate yoke 14,
A third magnet 17 and a fourth magnet 18 are provided on the inner peripheral surface. That is, the intermediate yoke 14 and the magnets 15 to 18 provided on the inner and outer peripheral surfaces thereof are disposed concentrically with the drive shaft 10 via the flanges 11 and 12,
And the output shaft 13 together with the movable body 30 which can move forward and backward in the axial direction. The predetermined radius R is substantially
It is の of the average value of the inner diameter of the first coil 5 (or the second coil 6) and the outer diameter of the third coil 7 (or the fourth coil 8).

Here, the structure of the movable body 30 is shown in FIGS.
This will be described with reference to FIG. FIG. 6 is a perspective view of the movable body 30,
FIG. 7 is a cross-sectional view, and FIGS.
It is an enlarged view of II part and IX part. As shown in FIGS. 6 and 7, the intermediate yoke 14 has a shape based on a cylindrical shape. However, only the intermediate yoke main body portion 14 a in the central portion in the axial direction has a cylindrical shape over the entire circumference. At both end sides, a protruding end portion 14b in which a part of the cylinder protrudes in the axial direction.
Are formed at equal intervals (120-degree intervals) in the circumferential direction. These protruding ends 14b are connected to the side plates 2 and 3
Are inserted through holes 2a and 3a (see FIG. 1 to FIG. 3) provided respectively. The protruding end 14b inserted into the holes 2a and 3a has a flange 11 at its axial end.
And 12 are attached and connected to the drive shaft 10 and the output shaft 13. As described above, since the load is applied to the protruding end portion 14b as a part of the output member, a predetermined mechanical strength is required. Therefore, it is preferable to provide at least three protruding ends 14b.

As described above, in the intermediate yoke 14, the intermediate yoke main body portion 14a and the protruding end portion 14b are formed as a single member instead of being formed separately.
With the simplification of the configuration, it becomes easy to secure a predetermined strength. On the other hand, the flanges 11 and 12 need not be made of a magnetic material, and may be made of a non-magnetic light metal such as aluminum. The use of a lightweight metal for the flanges 11 and 12 leads to a reduction in the weight of the movable body 30 as a whole.
The responsiveness of the operation is improved.

As shown in FIGS. 6 to 9, the first magnet 15,
The second magnet 16, the third magnet 17, and the fourth magnet 18 are respectively arranged in a cylindrical shape as a whole by a plurality of magnets divided in the circumferential direction. In the axial direction, the first magnet 15 and the third magnet
The magnet 17, the second magnet 16 and the fourth magnet 18 are provided at positions corresponding to each other. And
As shown in FIG. 8, the first magnet 15 (N-pole on the inner circumference side) and the third magnet 17 (S-pole on the outer circumference side) face the magnetic poles of different polarities in the radial direction with the intermediate yoke body 14a interposed therebetween. Are arranged as follows. Similarly, as shown in FIG. 9, the second magnet 16 (the inner peripheral side is S
) And the fourth magnet 18 (N-pole on the outer peripheral side) are arranged such that magnetic poles of different polarities are opposed to each other. Further, when viewed in the axial direction of the intermediate yoke body 14a, the first magnet 15
The second magnet 16 and the third magnet 17 versus the fourth magnet 18
Are arranged such that magnetic poles of different polarities are adjacent to each other. The first magnet 15 and the second magnet 16 maintain a predetermined air gap between the first coil 5 and the second coil 6, respectively, and the third magnet 17 and the fourth magnet 18 respectively correspond to the third coil 7 and the fourth coil 8, a predetermined air gap is maintained. Such an air gap is substantially the minimum air gap value.

In order to attach the magnets 15 to 18 to the intermediate yoke 14, first, the cylindrical outer magnet holding member 19 and the inner magnet holding member 20 shown in FIG. It is mounted at the center and fixed with screws 29. Next, the magnets 15 to 18 are attached to the entire inner and outer peripheries of the intermediate yoke main body 14a using an adhesive or the like. After that, the short cylindrical outer magnet holding member 21 and the inner magnet holding member 22 are attached to both ends of the intermediate yoke main body 14 a and fixed with screws 23. As shown in FIGS. 8 and 9, each of the magnet holding members 19 to 22 has a projection 19 a having a shape adapted to the groove at the edge of the magnet.
20a, 21a and 22a are provided, whereby the magnets 15 to 18 are securely held. Therefore, even when the adhesive deteriorates due to aging and loses its adhesive strength,
The magnets 15 to 18 can be prevented from falling off. The configuration of the movable body 30 is as described above.

Next, referring to FIG. 2 and FIG.
Bracket 25 is attached to one place on the outer circumference of
A potentiometer 26 is connected to the bracket 25. As shown in FIG. 4, the potentiometer 26 is fixed to the outer yoke 1, but the stroke of the rod end 27 can be adjusted in the axial direction. Movable body 30
The amount of displacement due to the forward / backward movement of is detected by the potentiometer 26.

As shown in FIGS. 2 and 5, an anti-rotation pin 28, which protrudes from the side plate 2 in the axial direction, is attached. The anti-rotation pin 28 is inserted through a hole 11a provided in the flange 11. I have. The inner diameter of the hole 11a is finished to a minimum value necessary for the flange 11 to allow the rotation preventing pin 28 to pass relatively smoothly as the movable body 30 advances and retreats.
The gap (play) with the gap a is sufficiently smaller than the gap B at both circumferential ends of the hole 2a of the side plate 2 and the protruding end 14b of the intermediate yoke 14 in FIG. Therefore, the movement of the movable body 30 in the same direction is restricted by restricting the movement of the flange 11 in the circumferential direction by the rotation preventing pin 28, and the protruding end portion 14b does not contact the circumferential end surface of the hole 2a. Therefore, it is possible to prevent the sliding resistance from increasing due to the protruding end portion 14b coming into contact with the circumferential end surface of the hole 2a. Also, the intermediate yoke 14
Drive shaft 10 supported by inner yoke 4 to flange 11
And 12, the movement is also restricted in the radial direction. Therefore, the sliding resistance does not increase because the protruding end portion 14b comes into contact with the radial end surface of the hole 2a.

In FIG. 3, the lead wires 23 and 24 are connected to a receptacle 31 attached to the side plate 3.

In the linear actuator configured as described above, the first magnet 15 and the third magnet 17 constitute one magnet body together with the intermediate yoke main body 14b existing therebetween, and the second magnet 16 and the fourth magnet The magnet 18 forms another magnet body together with the intermediate yoke main body 14b present therebetween. These paired magnet bodies form a closed magnetic circuit (magnetic flux loop) A shown in FIG. In this state, the first
When a current is applied to the coil 15 and the third coil 17 in a direction perpendicular to the paper of FIG. 1 and a current is applied to the second coil 16 and the fourth coil 18 in a direction perpendicular to the paper of FIG. 5 to 8 generate a force directed to the right side of the drawing. Due to the reaction of this force, the movable body 30 moves forward with a thrust to the left in the figure. Conversely, a current flows through the first coil 15 and the third coil 17 in a direction perpendicular to the plane of the drawing, and a current flows through the second coil 16 and the fourth coil 18 in a direction perpendicular to the plane of the drawing. And each coil 5
8 generate a force toward the left side of the figure. By the reaction of this force, the movable body 30 retreats by obtaining a thrust in the right direction in the figure.

In the forward / backward movement of the movable body 30, the movable body 3
0 of the drive shaft 10 through the slide bearing 9 and the inner yoke 4
The inner yoke 4 is supported (both supported) from both ends of the outer yoke 1 via the side plates 2 and 3. Therefore, even if vibration or impact is applied to the output shaft 13 of the movable body 30, the air gap between each of the magnets 15 to 18 and each of the coils 5 to 8 opposed thereto is substantially unchanged. As a result, the air gap can be set to the minimum necessary value as described above. The minimum required air gap minimizes the loss of magnetic energy,
The output increases.

The common closed magnetic path A formed by the pair of magnets penetrates the intermediate yoke 14 (the intermediate yoke main body 14a) perpendicularly in the radial direction. Therefore, the intermediate yoke 1
4 does not limit the magnetic flux. In other words, the intermediate yoke 14 can be made as thin as possible as long as the mechanical strength can be maintained. By reducing the thickness of the intermediate yoke 14, the movable body 30 is reduced in weight, and the responsiveness of the operation is improved.

In the above embodiment, the movable body 3
It is the inner yoke 4 that directly supports 0,
If necessary, a configuration in which the movable body 30 is directly supported by the outer yoke 1 is also possible.

[0037]

The present invention configured as described above has the following effects. According to the linear actuator of the first aspect, both ends of the inner yoke and the outer yoke are connected to each other, and the inner yoke is in a so-called double-supported support state by the outer yoke. The inner yoke or outer yoke supporting the movable body is not deformed by the impact, so that the air gap between the coil and the magnet is kept constant. Therefore, it is not necessary to set the air gap to a relatively large value, and the air gap can be set to a substantially minimum value, so that energy loss is reduced and output is increased.

According to the linear actuator of the second aspect, the inner yoke is supported by the outer yoke at both ends by the side plate, and the output can be taken out from the movable body penetrating the side plate. Can be taken out.

According to the linear actuator of the third aspect, since the common closed magnetic path formed by the magnets penetrates the intermediate yoke perpendicularly, the magnetic flux is not limited due to the thickness of the intermediate yoke, and therefore the intermediate yoke is not limited. The thickness of the yoke can be reduced as long as the mechanical strength can be maintained. Since the movable body is reduced in weight by making the intermediate yoke thinner, the responsiveness of the operation is improved.

According to the linear actuator of the fourth aspect, it is possible to transmit the driving force to the output shaft while securing the predetermined strength while reducing the weight of the movable body by the necessary minimum number of projecting ends. As a result, stable operation of the movable body and excellent responsiveness can be realized.

According to the linear actuator of the fifth aspect, it is possible to transmit the driving force to the output shaft while securing the predetermined strength while reducing the weight of the movable body by the necessary minimum number of projecting ends. As a result, stable operation of the movable body and excellent responsiveness can be realized.

According to the linear actuator of the sixth aspect, since the intermediate yoke can be integrally formed, its manufacture is easy.

According to the linear actuator of the present invention, since the rotation of the movable body in the circumferential direction is prevented by the rotation preventing means, the protruding end of the intermediate yoke comes into contact with the peripheral member to increase the sliding resistance. Can be prevented, and stable operation of the movable body can be ensured.

According to the linear actuator of the present invention, even if the magnet attached using an adhesive or the like is separated due to the aging of the adhesive, the magnet can be prevented from falling off, so that a highly reliable structure can be achieved. Is obtained.

According to the linear actuator of the ninth aspect, since the movement amount of the movable body can be detected by the potentiometer, the stroke control of the movable body becomes easy.

According to the tenth aspect of the present invention, since the slide bearing does not protrude from the end of the inner yoke, the sliding resistance of the drive shaft can be reduced without increasing the axial dimension of the linear actuator. Can be.

According to the linear actuator of the eleventh aspect, since the side plate plays a role of retaining the slide bearing, there is no need to separately provide a retaining member, which contributes to simplification of the structure.

According to the linear actuator of the twelfth aspect, the air gap can be reduced by the amount that the bobbin or the like is not used, thereby contributing to an increase in output.

According to the linear actuator of the thirteenth aspect, since the lead wire is hidden by the groove, the air gap can be reduced, which contributes to an increase in output.

According to the linear actuator of the fourteenth aspect, the weight of the movable body can be reduced by using a lightweight metal such as aluminum, so that the responsiveness of the operation of the movable body can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a linear actuator according to an embodiment of the present invention as viewed from the front side.

FIG. 2 is a left side view of the linear actuator.

FIG. 3 is a right side view of the linear actuator.

FIG. 4 is a partial sectional view taken along line IV-IV in FIG. 2;

FIG. 5 is a partial sectional view taken along line VV of FIG. 2;

FIG. 6 is a perspective view of a movable body in the linear actuator.

FIG. 7 is a sectional view of the movable body.

FIG. 8 is an enlarged view of a portion VIII in FIG. 7;

FIG. 9 is an enlarged view of a portion IX in FIG. 7;

FIG. 10 is a sectional view of a conventional linear actuator.

[Explanation of symbols]

 Reference Signs List 1 outer yoke 1b groove 2, 3 side plate 4 inner yoke 4b groove 5 first coil (outer coil) 6 second coil (outer coil) 7 third coil (inner coil) 8 fourth coil (inner coil) 9 slide bearing DESCRIPTION OF SYMBOLS 10 Drive shaft 11,12 Flange 13 Output shaft 14 Intermediate yoke 14a Intermediate yoke main part 14b Protruding end part 15 1st magnet 16 2nd magnet 17 3rd magnet 18 4th magnet 19,21 Outer magnet holding member 20,22 Inner magnet Holding member 23, 24 Lead wire 26 Potentiometer 28 Rotation prevention pin 30 Movable body

Claims (14)

[Claims] A cylindrical outer yoke, an outer coil provided on an inner peripheral surface of the outer yoke, connected to the outer yoke at both ends in an axial direction, and arranged concentrically inside the outer yoke. An inner yoke; an inner coil provided on an outer peripheral surface of the inner yoke; a cylindrical intermediate yoke disposed coaxially with the outer yoke and the inner yoke; an output connected to the intermediate yoke A shaft, and a magnet provided on the outer peripheral surface and the inner peripheral surface of the intermediate yoke, respectively, in opposition to the outer coil and the inner coil, wherein at least one of the outer yoke and the inner yoke A linear actuator comprising: a movable body supported so as to be able to advance and retreat in an axial direction. 2. A pair of side plates are provided on both axial end surfaces of the outer yoke, the inner yoke is fixed to the pair of side plates, and the movable body penetrates the pair of side plates. Claim 1 characterized by the following:
The linear actuator as described. 3. The first magnet and the second magnet, which are arranged on the outer peripheral surface of the intermediate yoke at a distance from each other in the axial direction, and the first magnet and the second magnet on the inner peripheral surface of the intermediate yoke. A third magnet and a fourth magnet arranged at positions corresponding to the second magnet, respectively, wherein the first magnet and the second magnet, the third magnet and the fourth magnet, 2. The linear actuator according to claim 1, wherein the first magnet and the third magnet and the second magnet and the fourth magnet have polar arrangements in which different polarities are opposed to each other. 3. 4. The linear actuator according to claim 1, wherein the intermediate yoke has at least three protruding ends formed at both ends in the axial direction. 5. The intermediate yoke has at least three protruding ends formed at both ends in the axial direction, and these protruding ends penetrate the side plate. Linear actuator. 6. The linear actuator according to claim 3, wherein said intermediate yoke is made of a magnetic material over its entire length in the axial direction. 7. The linear actuator according to claim 4, wherein said movable body is provided with a rotation preventing means in a circumferential direction. 8. The linear actuator according to claim 6, wherein a magnet holding member is provided on an inner peripheral surface and an outer peripheral surface of said intermediate yoke adjacent to each of said first to fourth magnets. 9. A linear actuator according to claim 1, wherein a potentiometer is connected to said movable body in parallel with an axial direction thereof. 10. The movable body according to claim 1, wherein the movable body has a drive shaft at an axial center thereof, and a slide bearing is provided in an opposing section between the drive shaft and the inner yoke. Linear actuator. 11. The movable body has a drive shaft at an axial center thereof, a slide bearing is provided in a section facing the drive shaft and the inner yoke, and the side plate is adjacent to one end of the slide bearing. 3. The method according to claim 2, wherein
The linear actuator as described. 12. The outer coil and the inner coil,
2. The linear actuator according to claim 1, wherein each of the coils is a bobbin-less rectangular coil. 13. The inner coil and the outer coil are single-phase wound, and each lead wire is led out through a groove formed in the inner yoke and the outer yoke. Linear actuator. 14. The linear actuator according to claim 1, wherein the movable body includes a flange connecting the intermediate yoke and the output shaft, and the flange is made of a non-magnetic material.