JP5329910B2 - Linear actuator - Google Patents

Description

  The present invention relates to a linear actuator.

  Conventionally, as this type of linear actuator, for example, a bottomed cylindrical outer yoke, a bottomed cylindrical inner yoke that is movably inserted into the outer yoke, and a bottom portion of the outer yoke rises into the inner yoke. A guide rod that is slidably inserted through a bearing, a core that includes a plurality of coils provided on the inner periphery of the outer yoke, and a plurality of permanent magnets that are arranged in the axial direction on the outer periphery of the inner yoke. (See Patent Document 1).

In this linear actuator, the relative movement in the axial direction of the outer yoke and the inner yoke is guided by the guide rod to achieve smooth expansion and contraction.
JP 2007-274820 A (FIG. 1)

  Since the conventional linear actuator includes the guide rod as described above, there is no problem as long as only an external force in the axial direction acts on the mounting portion provided at the bottom of each of the outer yoke and the inner yoke. When the bending moment is applied to the linear actuator via each mounting part, the guide rod is slidably contacted with the inner circumference of the inner yoke, so that the bending moment is also applied to the inner yoke. Become.

  In this way, when the bending moment acts on the inner yoke, the inner yoke is distorted, but the inner yoke is attached with a permanent magnet on the outer periphery, and the permanent magnet peels off from the inner yoke due to the strain. Or the permanent magnet may crack.

  Furthermore, in the above linear actuator, a cylindrical cover that covers the outer periphery of the outer yoke is provided at the end of the inner yoke for internal protection, and a seal member that slides on the outer periphery of the outer yoke on the inner periphery of the cover Since the structure is such that the radial movement of the outer yoke is constrained by the cover, the moment acts on the core in the outer yoke to distort the core, and the coil mounted on the core There is also a risk of peeling or disconnection.

  Therefore, the present invention has been developed to improve the above-described problems, and an object of the present invention is to provide a linear actuator that can prevent the permanent magnet and the coil from being peeled off or damaged.

To achieve the above object, problem-solving means of the present invention, the rod, a plurality of the magnetic field to be held in the rod comprises a permanent magnet, a coil holding member disposed so as to face the field internal and a plurality of coils, in the linear actuator for generating a thrust force for relatively displacing the coil holding member and said rod in the axial direction, the coil holding member with a bottom portion is connected to one end of the rod to be held in an inner tube and a bottomed cylindrical outer tube for accommodating the end of the outer tube side while being slidably inserted into the outer tube is connected to the coil holding member, provided in the inner tube And a bearing that is in sliding contact with the inner periphery of the outer tube, and the coil holding member is more out of the bearing than the bearing. Characterized by connecting to the inner tube at the bottom side of the over tube.

In the linear actuator of the present invention, the inner tube is slidably inserted into the outer tube. Even if a bending moment is applied, the bending moment is applied to the outer tube and the inner tube, but the rod is the bottom of the outer tube. in conjunction with coupled, the coil holding member Ru is connected to the end of the outer tube side of the inner tube. And while providing the bearing provided in an inner tube and slidingly contacting with the inner periphery of an outer tube, a coil holding member is connected with an inner tube at the bottom part side of an outer tube rather than a bearing. Thereby , a bending moment does not act on a rod and a coil holding member, and it does not distort.

  Therefore, the permanent magnet fixed to the rod is prevented from being peeled off or damaged, and the coil is prevented from being peeled off or the coil is disconnected from the coil holding member.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a linear actuator according to an embodiment of the present invention.

  In one embodiment, as shown in FIG. 1, the linear actuator 1 includes a rod 2, a field 3 held by the rod 2 with a plurality of permanent magnets 4, and a field 3. A plurality of coils 6 held by a core 5 as a coil holding member, a bottomed cylindrical outer tube 7 in which a bottom portion 7a is connected to one end 2a of the rod 2 and the core 5 is accommodated therein, and an outer tube An outer tube that is slidably inserted into the outer tube 7 and is connected to the rod 2 by exciting the coil 6. 7 and the inner tube 8 connected to the core 5 can generate a thrust that relatively displaces in the axial direction.

  Hereinafter, each part of the linear actuator 1 will be described in detail. In the case of this embodiment, the rod 2 has a cylindrical shape, and holds a plurality of annular permanent magnets 4 arranged on the outer periphery in an axial direction. In this case, the permanent magnets 4 are magnetized so that the poles are different between the inner periphery and the outer periphery, and are arranged on the rod 2 in the axial direction with a predetermined interval between them. It is fixedly attached to the outer periphery of the rod 2 by bonding or the like so that different poles appear.

  Therefore, a magnetic field that acts on the coil 6 is generated on the outer periphery of the rod 2 by these permanent magnets 4, and the field magnet 3 in the linear actuator 1 is configured by these permanent magnets 4. As shown in the drawing, nine permanent magnets 4 are provided on the rod 2, but as long as the linear actuator 1 can be driven, the number of the permanent magnets 4 is not limited to this.

  In addition, since the magnetic flux concentrates in the rod 2 when the rod 2 is formed of a ferromagnetic material and affects the magnetic flux around the outer periphery of the permanent magnet 4, the rod 2 is preferably formed of a non-magnetic material.

  In this embodiment, the rod 2 is a cylinder. However, the rod 2 may be a cylinder. If the rod 2 is a cylinder, a disk-shaped permanent magnet is disposed inside and the S pole and the N pole are arranged on the outer periphery. The field may be constituted by a plurality of permanent magnets inserted into the rod by being stacked so as to appear alternately along the axial direction. When the rod is cylindrical as described above, it is desirable that the rod be formed of a non-magnetic material so as not to prevent the transmission of the magnetic flux of the permanent magnet.

  The rod 2 holding the permanent magnet 4 as described above has one end 2 a connected to the bottom 7 a of the bottomed cylindrical outer tube 7. When connecting the rod 2 to the outer tube 7, fitting, screw fastening, and other various connecting methods can be employed. The outer tube 7 includes a bottom portion 7a and a cylindrical portion 7b, and has a bottomed cylindrical shape as described above. An annular flange 7c that protrudes inward is formed at the left end in FIG. 1 serving as an opening end of the cylindrical portion 7b. In addition to being provided, an inner diameter is set to a large diameter from an intermediate portion of the cylindrical portion 7b to the flange 7c, a large diameter portion 7d is provided, and a step portion 7e is formed at the end of the large diameter portion 7d.

  A mounting portion 9 having a mounting hole that allows the linear actuator 1 to be mounted on a device is mounted on the outer end of the bottom portion 7a of the outer tube 7, and an annular outer bearing 10 that is annular on the inner periphery of the flange 7c. Holding.

  A cylindrical core 5 is inserted between the outer tube 7 and the rod 2 so as to be movable. The core 5 has a plurality of slots 5a for accommodating the coils 6, and both ends and between the slots 5a and 5a. And a plurality of pole teeth 5b provided.

In this case, the core 5 thus configured has a cylindrical shape, and has an inner circumference opposed to the field 3 of the rod 2. The coil 2 is excited to magnetize the pole teeth 5 b, thereby the rod 2. The permanent magnet 4 of the field 3 is attracted and repelled to generate a thrust force that causes the rod 2 and the core 5 to relatively displace in the axial direction. The core 5 does not necessarily have a cylindrical shape, and the field 3 held by the rod 2 does not form a magnetic field over the entire outer periphery of the rod 2, and does not generate a magnetic field in the direction facing the core 5. However, the permanent magnet 4 may be cylindrical or disc-shaped to generate a magnetic field on the outer periphery of the rod 2, and the core 5 may be formed in a cylindrical shape so as to surround the outer periphery of the rod 2. On the other hand, there is an advantage that the thrust does not change even if the rod 2 rotates in the circumferential direction. In this embodiment, the coil holding member is the core 5 and the coil 6 is attached to the core 5. However, the coil holding member is a cylinder and the coil 6 is directly attached to the cylinder. Is also possible.

  More specifically, the coil 6 is mounted in the slot 5a so as to surround the outer periphery of the rod 2. As shown in the figure, the core 5 is provided with a total of six U phases, two V phases, and two W phases. The U phase, the V phase, and the W phase are arranged in this order. For example, the energization phase is switched based on the electrical angle of the core 5 with respect to the rod 2 and the amount of current of each coil 6 is controlled by PWM control to control the thrust of the linear actuator 1 and the direction in which the thrust is generated. Can be done. In controlling the linear actuator 1, it is only necessary to know the relative position of the permanent magnet 4 with respect to the core 5, and therefore a means capable of grasping the relative position of the magnetic sensor or the like may be provided. The number of coils 6 may be set to a number suitable for the thrust generated by the linear actuator 1 and the energization method.

  The core 5 is connected to an end 8a on the outer tube side of the inner tube 8, and the inner tube 8 has a bottomed cylindrical shape and is provided with a flange 8b on the outer periphery of the end 8a on the outer tube side. The annular inner bearing 11 is held on the outer periphery of the flange 8b. A mounting portion 12 having a mounting hole that allows the inner tube 8 to be attached to a device is attached to the outer end of the bottom portion of the inner tube 8.

  The inner tube 8 configured in this manner is inserted into the outer tube 7, and the outer periphery thereof is slidably supported by an outer bearing 10 held by the outer tube 7, and the inner tube 8 itself holds. The outer periphery of the side bearing 11 is brought into sliding contact with the inner periphery of the large diameter portion 7 d of the outer tube 7. Therefore, the inner tube 8 is slidably inserted into the outer tube 7.

  Then, when the inner tube 8 is relatively displaced in the direction of retreating from the outer tube 7 and the right end in FIG. 1 of the flange 7c and the left end in FIG. 1 of the flange 8b collide, further extension of the linear actuator 1 is restricted. On the contrary, when the inner tube 8 is relatively displaced in the direction of entering the outer tube 7 and the right end in FIG. 1 of the flange 8b and the left end in FIG. 1 of the stepped portion 7e collide, further contraction of the linear actuator 1 is restricted. It has come to be.

  As described above, the stroke range of the inner tube 8 with respect to the outer tube 7 is defined by the above-described flange 8b, flange 7c, and stepped portion 7e. Within this stroke range, the core 5 must be the axis of the field 3 of the rod 2 without fail. It is located within the direction length range and faces the field 3, thereby preventing the linear actuator 1 from being unable to generate thrust.

  Note that the cable 13 for connecting the coil 6 to an external power source (not shown) is connected to the inner tube 8 so that the linear actuator 1 can be expanded and contracted by being held by the inner tube 8 as shown. In some cases, there is an advantage that the cable 13 can be prevented from being disconnected without causing the cable 13 to be bent, and the rotation of the rod 2 with respect to the core 5 can be allowed, but this can also be held by the outer tube 7.

  Now, the linear actuator 1 is configured as described above, and by energizing the coil 6, it generates a thrust force that relatively displaces the rod 2 and the core 5, and relatively displaces the inner tube 8 and the outer tube 7 connected thereto. It can be expanded and contracted.

  Further, when an external force that relatively displaces the inner tube 8 and the outer tube 7 in the axial direction is applied, a thrust that suppresses the relative displacement is generated by energizing the coil 6 or an induced electromotive force generated in the coil 6. It is also possible to cause the linear actuator 1 to dampen the vibration and movement of the device due to the external force.

  In the linear actuator 1, when a bending moment is applied from the mounting portions 9 and 12, the inner tube 8 is slidably inserted into the outer tube 7. Although acting on the tube 8, the rod 2 is connected to the bottom 7 a of the outer tube 7, and the core 5 serving as a coil holding member is connected to the end 8 a on the outer tube side of the inner tube 8. And the bending moment does not act on the core 5 which is a coil holding member, and there is no distortion.

  Therefore, the permanent magnet 4 fixed to the rod 2 is prevented from being peeled off or damaged, and the coil 6 is prevented from being peeled off from the core 5 as a coil holding member or the coil 6 is disconnected. Will be.

  In the present invention, the inner tube 8 and the outer tube 7 are not subjected to a bending moment and transmitted to the rod 2 and the core 5 as the coil holding member. It is possible to eliminate the flange 7c, the flange 8b and the stepped portion 7e, and to directly contact the outer periphery of the inner tube 8 to the outer periphery of the outer tube 7, but by using the bearings 10 and 11, Wear of the inner tube 8 and the outer tube 7 can be suppressed, and these can be smoothly displaced relatively.

  Further, the field 3 and the core 5 serving as the coil holding member can be accommodated in the space formed between the outer tube 7 and the inner tube 8 without providing a cylindrical cover on the outer periphery of the outer tube 7. There is also an advantage that the drive unit of the linear actuator 1 can be protected from external interference. In addition, when it is desired to prevent dust and dust from entering between the outer bearing 10 of the outer tube 7 and the outer periphery of the inner tube 8, it is shown on the inner periphery of the open end of the cylindrical portion 7b of the outer tube 7. By the way, you may make it provide a sealing member in the inner periphery of the flange 7c.

  Furthermore, a cushion is provided on one of the left end of the flange 8b of the inner tube 8 and the right end of the flange 7c of the outer tube 7, and one of the right end of the flange 8c of the inner tube 8 and the right end of the flange 7c of the outer tube 7 is linearly provided. You may make it relieve | moderate the impact at the time of the maximum expansion | extension of the actuator 1, and the maximum contraction.

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is of course not limited to the details shown or described.

It is a cross-sectional view of the linear actuator in one embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Linear actuator 2 Rod 2a End of rod 3 Field 4 Permanent magnet 5 Core 5a which is a coil holding member Slot 5b in core Core pole 6 in coil 7 Outer tube 7a Bottom portion 7b in outer tube Cylindrical portion 7c in outer tube Flange 7d Large-diameter portion 7e in the outer tube Step portion 8 in the outer tube 8 Inner tube 8a End portion 8b on the outer tube side in the inner tube 鍔 9, 12 Mounting portion in the inner tube 10 Outer side bearing 11 Inner side bearing 13 Cable

Claims (4)

Includes a rod, a magnetic field held in the rod includes a plurality of permanent magnets, and a plurality of coils held in the coil holding member disposed so as to face the field, the said rod coil in the linear actuator generating a thrust force for relatively displacing the retaining member in the axial direction, and the bottomed cylindrical outer tube housing the coil holding member in the internal with the bottom is connected to one end of the rod, within said outer tube comprising an inner tube end of the outer tube side is connected to the coil holding member while being inserted slidably, the inner periphery in sliding contact bearing of the outer tube is provided on the inner tube, the coil holding member is connected to the inner tube at the bottom side of the outer tube than the bearing Linear actuator according to claim and.
Wherein mounted on the inner periphery of the open end of the outer tube comprising a sliding contact ring on the outer side bearing on an outer periphery of the inner tube, wherein said bearing is mounted on the outer periphery of an end portion of the outer tube side of the inner tube outer The linear actuator according to claim 1, wherein the linear actuator is an annular inner bearing that is in sliding contact with the inner periphery of the tube.
The provided a flange for holding the outer side bearing the inner periphery with inwardly projecting into the open end of the outer tube, the inner side bearing with outwardly projecting an end portion of the outer tube side of the inner tube a collar for holding is provided, the said internal diameter of a portion the inner side bearing sliding contact of the outer tube is set to a larger diameter than the other portion of the stepped portion formed on the inner periphery of the outer tube, and said flange and said flange elongation at abutment is regulated, linear actuator according to claim 2 which shrinks upon abutment between the flange and the stepped portion is characterized in that it is regulated.
Linear actuator according to any one of claims 1 to 3, characterized in that the cable connecting the coil to an external power supply is held in the inner tube.

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