JP5426935B2 - 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 cylinder, a rod that is movably inserted into the outer cylinder, a plurality of coils provided on the inner circumference of the outer cylinder, and an outer circumference of the rod And a plurality of permanent magnets arranged side by side in the axial direction, and drives the rod in the axial direction with respect to the outer cylinder (see Patent Document 1).

  In this linear actuator, the end of the rod is slidably inserted into the hole provided in the bottom of the outer cylinder, and the side of the rod is slidably supported by the open end of the outer cylinder. By doing so, the movement of the rod is guided to achieve a smooth expansion and contraction.

JP 2001-320868 A (FIG. 1)

In the conventional linear actuator, as described above, the rod is supported at two locations on the outer cylinder, and a coil is mounted between the two locations on which the rod of the outer cylinder is supported. When a lateral force is input to the end of the rod and a bending moment is applied to the outer cylinder, if the outer cylinder is greatly bent , the coil may be detached from the outer cylinder or the coil may be disconnected.

Therefore, the present invention was devised to improve the above-described problems, and an object of the present invention is to provide a linear actuator that does not cause coil peeling or disconnection .

To achieve the above object, problem-solving means of the present invention, the rod and, a magnetic field held in the rod includes a plurality of permanent magnets, a coil holding member disposed so as to face the field If, comprising an outer tube having a plurality of coils which are held in the coil holding member, an opening in which the rod is inserted with pivotally supported to the rod end to the inside is inserted in two locations, the coil Is a linear actuator that generates a thrust force that relatively displaces the rod and the coil holding member in the axial direction by exciting the coil, and the coil holding member is more open than the portion of the outer tube that pivotally supports the rod. It is connected to the part side .

  According to the linear actuator of the present invention, even when a bending moment is applied from the mounting portion, the outer tube provided with the mounting portion pivotally supports two portions of the rod, and holds the coil at the end of the outer tube. Bending moment does not act on the connected covers, and there is no distortion.

Therefore , since the bending moment does not act, it is possible to prevent the coil from being peeled off from the coil holding member or the coil from being disconnected.

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

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 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 cylindrical cover 5 serving as a coil holding member and a rod 2 into which one end 2a is inserted are pivotally supported at two locations and a mounting portion 7d for an external device (not shown) is provided. The outer tube 7 is provided, and by exciting the coil 6, it is possible to generate a thrust that relatively displaces the rod 2 and the cover 5 connected to the outer tube 7 in the axial direction. ing.

  Hereinafter, each part of the linear actuator 1 will be described in detail. In this embodiment, the rod 2 includes an inner rod 8 and a pipe 9 that forms an annular gap between the inner rod 8 and the inner rod 8.

  The inner rod 8 is connected to the large diameter portions 8a and 8b provided at both ends, the bearing holding portion 8c having a larger diameter than the large diameter portion 8a connected to one large diameter portion 8a, and the other large diameter portion 8b. And a pipe 9 is mounted on the outer circumference of the large diameter portions 8a and 8b to form an annular gap between the large diameter portions 8a and 8b of the inner rod 8, and the annular gap A plurality of annular permanent magnets 4 arranged in the axial direction are accommodated therein.

  An annular rod-side bearing 10 that is in sliding contact with the inner periphery of the outer tube 7 is mounted on the outer periphery of the bearing holding portion 8 c that is one end 2 a of the rod 2.

  Further, the permanent magnet 4 is held in the rod 2 by being accommodated in the annular gap. In this case, the permanent magnet 4 is magnetized so that the N pole and the S pole appear in the axial direction, and the adjacent permanent magnet 4 is held side by side on the rod 2 in the axial direction with the same poles facing each other. 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.

  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 the figure, six permanent magnets 4 are provided on the rod 2. However, as long as the linear actuator 1 can be driven, the number of the permanent magnets 4 is not limited to this.

  Furthermore, in this embodiment, the rod 2 is composed of the inner rod 8 and the pipe 9, but the permanent magnet 4 may be mounted on the outer periphery as a simple cylinder. Further, the permanent magnet 4 may be magnetized so that the poles are different between the inner periphery and the outer periphery, and in any case, the S pole and the N pole appear alternately along the axial direction of the rod 2. It only has to be. Further, the large-diameter portions 8a and 8b of the inner rod 8 are divided, the large-diameter portions 8a and 8b are connected by the pipe 9, the rod 2 has a hollow structure, and a permanent magnet is laminated in the pipe 9. May be adopted.

Then, the rod 2 holding the permanent magnet 4 as described above, one end 2a is inserted movably in a bottomed cylindrical outer tube 7, mounted on the outer periphery of the bearing holding portion 8c to be one end 2a The rod-side bearing 10 thus made is brought into sliding contact with the inner periphery of the outer tube 7. The rod-side bearing 10 is made of, for example, synthetic resin, and does not bite the inner periphery of the outer tube 7 at the outer peripheral edges at both ends when sliding on the inner periphery of the outer tube 7. ing. Accordingly, stick-slip is less likely to occur when the rod-side bearing 10 and the outer tube 7 slide.

The outer tube 7 has a bottom portion 7a and a cylindrical portion 7b and has a bottomed cylindrical shape as described above, and protrudes inward at the right end in FIG. 1 serving as an opening portion of the cylindrical portion 7b through which the rod 2 is inserted . An annular flange 7c is provided, and an attachment portion 7d capable of attaching the outer tube 7 to an external device (not shown) is provided on the bottom portion 7a. The mounting portion 8d in the rod 2 and the mounting portion 7d in the outer tube 7 are both clevises having holes, but may be mounting brackets that are suitable for the external device to which the linear actuator 1 is mounted. . Further, the attachment portion 8d and the attachment portion 7d do not have to be provided on the axes of the rod 2 and the outer tube 7.

  Further, an outer bearing 11 that is in sliding contact with the pipe 9 that is the outer periphery of the rod 2 is mounted on the inner periphery of the flange 7c. The outer bearing 11 is also made of, for example, a synthetic resin, like the rod bearing 10, so that when the outer periphery of the rod 2 slides, the outer periphery of the rod 2 does not bite the outer periphery of both ends. It is difficult to cause stick-slip.

  Therefore, the rod 2 and the outer tube 7 can exhibit smooth relative movement in the axial direction. Further, the large-diameter slide bearing holding portion 8c provided at the one end 2a of the rod 2 can be brought into contact with the flange 7c of the outer tube 7, and the rod 2 is prevented from coming off from the outer tube 7.

And the cover 5 as a coil holding member is connected with the said opening part side rather than the location which pivotally supports the rod 2 in this outer tube 7. FIG. More particularly, the rod-side end is the right end in FIG. 1 of the outer tube 7, cover 5 is connected in the axial direction. The cover 5 has a cylindrical shape, holds a core 12 around which the coil 6 is wound, and holds the coil 6 via the core 12.

  The cover 5 is connected to the outer tube 7 at the end on the outer tube side which is the left end in FIG. 1, and the flange 5a which protrudes to the inner peripheral side is provided at the end on the opposite outer tube side which is the right end in FIG. An annular dust seal 13 slidably contacting the outer periphery of the rod 2 is provided on the inner periphery of the flange 5a. By providing the dust seal 13 with the cover 5 having a cylindrical shape in this way, the inside of the cover 5 and the outer tube 7 is sealed by the dust seal 13, and there is an advantage that dust can be prevented from entering the inside. However, the cover 5 may not be cylindrical.

  The core 12 includes a plurality of slots 12a for accommodating the coils 6 and a plurality of pole teeth 12b provided at both ends and between the slots 12a and 12a.

  In this case, the core 12 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 12 b, thereby the rod 2. By thrusting and repelling the permanent magnet 4 of the field 3, a thrust force that causes relative displacement in the axial direction is generated in the cover 5 that holds the rod 2 and the core 12. The core 12 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 a direction facing the core 12. However, the permanent magnet 4 may be formed in a cylindrical or disk shape to generate a magnetic field on the outer periphery of the rod 2 and the core 12 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 the present embodiment, the coil holding member is used as the cover 5 and the coil 6 is attached to the cover 5 via the core 12. However, the coil holding member is used as the core and the cover is abolished, It is also possible to eliminate the core 12 by directly attaching the coil 6 to 5.

  Subsequently, the coil 6 is mounted in the slot 12a so as to surround the outer periphery of the rod 2, and in the figure, the core 12 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 12 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 12, 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.

  Now, the linear actuator 1 is configured as described above. When the coil 6 is energized, it generates a thrust force that relatively displaces the rod 2 and the cover 5 and relative displacement with the outer tube 7 connected to the rod 2 and the cover 5. It can be expanded and contracted.

  Further, when an external force that relatively displaces the rod 2 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. Thus, it is possible to cause the linear actuator 1 to dampen the vibration and movement of the device due to the external force.

  And in this linear actuator 1, even if a bending moment acts from attachment part 8d, 7d, the outer tube 7 provided with attachment part 7d pivotally supports two places of the rod 2, and coil 6 is attached. A bending moment does not act on the cover 5 that is held and connected to the end of the outer tube 7 and is not distorted.

  Further, since the bending moment does not act, it is possible to prevent the coil 6 from being peeled off from the cover 5 as the coil holding member or the coil 6 from being disconnected.

  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.

The present invention can be used for a linear actuator.

DESCRIPTION OF SYMBOLS 1 Linear actuator 2 Rod 2a End of rod 3 Field 4 Permanent magnet 5 Cover 5a which is a coil holding member Flange 6 Coil 7 Outer tube 7a Bottom part 7b in outer tube Cylindrical part 7c in outer tube Flange 7d in outer tube Mounting part in outer tube 8 Inner rod 8a, 8b Large diameter portion 8c in inner rod Bearing holding portion 8d in inner rod Mounting portion 9 in inner rod 9 Pipe 10 Rod side bearing 11 Outer side bearing 12 Core 12a Core slot 12b Core pole teeth 13 Dust seal

Claims (3)

The rod,
A magnetic field held in the rod includes a plurality of permanent magnets,
A coil holding member disposed so as to face the field,
A plurality of coils held by the coil holding member ;
Comprising an outer tube having an opening in which the rod is inserted with pivotally supported at two places of the rod having one end internally is inserted,
A linear actuator that generates a thrust force that relatively displaces the rod and the coil holding member in the axial direction by exciting the coil,
The linear actuator , wherein the coil holding member is connected to the opening side of a portion of the outer tube that pivotally supports the rod . Provided with an annular rod-side bearing sliding contact with the one end of the outer tube of the rod, linear according to claim 1, characterized in that a outer side bearing in sliding contact with the outer circumference of the rod in the outer tube Actuator. Linear actuator according to claim 1 in which the coil holding member is a cylindrical, characterized in that a sliding contact dust seal on the outer circumference of the rod in the anti-outer tube end.

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