JP5452090B2 - Linear actuator - Google Patents

Description

  The present invention relates to a linear actuator.

  Conventionally, as this type of linear actuator, for example, an outer tube, a rod that is movably inserted into the outer tube, a field that is provided with a plurality of permanent magnets and that is held in the rod, and is opposed to the field A plurality of coils that are held side by side in the axial direction on the outer tube, and a sliding member that is attached to the inner periphery of both ends of the outer tube via elastic bodies and that slides on the outer periphery of the rod. The relative movement between the tube and the rod is guided by these sliding members (for example, see Patent Document 1).

JP 2007-195349 A (FIGS. 1 and 2)

  In the conventional linear actuator, as described above, the axial movement of the rod relative to the outer tube is guided by the two sliding members arranged at both ends of the outer tube and elastically supported by the elastic body. Alternatively, even if the rod is bent by the action of the moment, the sliding resistance can be reduced by deformation of the elastic body, but the bending of the rod itself cannot be reduced.

  As described above, when the rod is bent, the positional relationship in the axial direction and the radial direction between the permanent magnet and the coil held by the rod may be deviated from the initial setting, which may cause a problem such as energy loss.

  Accordingly, the present invention has been made to improve the above-described problems, and an object of the present invention is to provide a linear actuator that can reduce the bending of the rod.

  In order to achieve the above object, the problem-solving means of the present invention includes an outer tube, a rod that is movably inserted into the outer tube, and a plurality of permanent magnets, and is held by either the outer tube or the rod. And a linear actuator that generates a thrust that relatively displaces the outer tube and the rod in the axial direction. A first sliding contact portion that is held by one of the tube and the rod and is in sliding contact with the other; a second sliding contact portion that is held by either the outer tube and the rod and is in sliding contact with the other; and the outer tube and the rod A third sliding contact portion that is held by either one and slidably contacts the other and is disposed between the first sliding contact portion and the second sliding contact portion in the axial direction. The provided, characterized in that to guide the relative movement of the outer tube and the rod at these three sliding contact portion.

  According to the linear actuator of the present invention, the first sliding contact portion that is held on one of the outer tube and the rod and is in sliding contact with the other, and the second that is held on either the outer tube and the rod and that is in sliding contact with the other. A sliding contact portion, and a third sliding contact portion which is held by one of the outer tube and the rod and is in sliding contact with the other and is disposed between the first sliding contact portion and the second sliding contact portion in the axial direction. Since these three sliding contact portions guide the relative movement of the outer tube and the rod, even if the axial distance between the first sliding contact portion and the second sliding contact portion is long, The rod is pivotally supported by the intermediate third sliding contact portion, and the bending of the rod can be reduced.

  In addition, since the bending of the rod is reduced, the frictional resistance at the first sliding contact portion, the second sliding contact portion, and the third sliding contact portion is also reduced, so that the axial relative smoothness between the outer tube and the rod is reduced. Move can be realized.

  Further, since the bending of the rod is reduced, the relative positions of the field and the coil in the axial direction and the radial direction are maintained substantially as set, and energy loss during driving can be reduced. .

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

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the linear actuator 1 according to an embodiment includes an outer tube 2, a rod 3 that is movably inserted into the outer tube 2, and a plurality of permanent magnets 5. A first coil 7a and a second coil 7b each made of a plurality of coils held on the outer tube 2 so as to face the field 4, and a rod held on the inner periphery of the outer tube 2 3, a first sliding contact portion 8 that is in sliding contact with the outer periphery of the outer ring 2, a second sliding contact portion 9 that is held on the inner periphery of the outer tube 2 and that is in sliding contact with the outer periphery of the rod 3, and an outer tube 2 that is held on the outer periphery of the rod 3. And a third slidable contact portion 10 that is slidably contacted with the inner periphery of the rod. The rod 3 that holds the field 4 and the coils 7a and 7b are held by appropriately exciting the coils 7a and 7b. A It is possible to generate a thrust force that relatively displaces the turbine tube 2 in the axial direction, and the relative movement between the outer tube 2 and the rod 3 is guided by the sliding contact portions 8, 9, and 10 described above. Yes.

  Hereinafter, each part of the linear actuator 1 will be described in detail. In this embodiment, the rod 3 includes an inner rod 31 and two pipes 32 and 33 that form an annular gap between the inner rod 31 and the inner rod 31.

  The inner rod 31 includes a shaft 34, flanges 35, 36, and 37 provided at both ends and in the middle of the shaft 34, a large-diameter portion 38 provided on the outer periphery of the flange 36 located in the middle of the shaft 34, An attachment portion 41 provided at the end portion is provided, and a slide ring 39 is mounted on the outer periphery of the large diameter portion 38. The rod 3 can be connected to an external device outside the figure via the mounting portion 41.

  In addition, the pipe 32 is attached to the outer periphery of the flanges 35, 36, an annular gap is formed between the shaft 34 and the pipe 32, and the pipe 33 is also attached to the outer periphery of the flanges 36, 37. An annular gap is formed between the shaft 34 and the pipe 33. The pipe 32 is sandwiched between a large-diameter portion 38 provided on the outer periphery of the flange 36 and a shoulder portion 35a provided on the outer periphery of the flange 35 on the flange 36 side and fixed to the inner rod 31. The pipe 33 is connected to the flange 36. Are fixed to the inner rod 31 by being sandwiched between a large-diameter portion 38 provided on the outer periphery of the flange 37 and a shoulder portion 37a provided on the outer periphery of the flange 37 on the flange 36 side.

  As described above, the rod 3 includes a large-diameter portion 38 projecting radially outward in the middle, and a slide ring 39 attached to the outer periphery of the large-diameter portion 37 is slid on the inner periphery of the outer tube 2. Touching. In this embodiment, the third sliding contact portion 10 is formed by the large diameter portion 38 and the slide ring 39. In this case, the slide ring 39 is made of a synthetic resin, When the inner periphery of the tube 2 is slid, the inner periphery of the outer tube 2 is not squeezed by the outer peripheral edges of both ends. Therefore, stick slip is less likely to occur when the third sliding contact portion 10 and the outer tube 2 slide. When the large diameter portion 38 of the inner rod 31 is made of a material suitable for sliding with low friction, the slide ring 39 is omitted and only the large diameter portion 38 forms the third sliding contact portion 10. May be.

  Further, in the two annular gaps formed between the pipes 32 and 33 and the shaft 34, a plurality of annular permanent magnets 5 arranged in the axial direction are accommodated. The permanent magnet 5 is held in the rod 3 by being accommodated in the annular gap. In this case, the permanent magnet 5 is magnetized so that the N pole and the S pole appear in the axial direction. The same poles are opposed to each other and held on the rod 3 in the axial direction. Spacers 40 are provided at both ends of the group of permanent magnets 5 accommodated between the pipe 32 and the shaft 34 and between the pipe 33 and the shaft 34, respectively. It is positioned and fixed in each annular gap, but may be eliminated if the spacer 40 is unnecessary.

  The group of permanent magnets 5 accommodated in the annular gap between the pipe 32 and the shaft 34 constitutes the first field 4a, and the group of permanent magnets accommodated in the annular gap between the pipe 33 and the shaft 34. The magnet 5 constitutes a second field 4b, and the field 4 is composed of the first field 4a and the second field 4b.

  When the rod 3 is made of a ferromagnetic material, the magnetic flux concentrates in the rod 3 and affects the magnetic flux around the outer periphery of the permanent magnet 5, so that the rod 3 is preferably made of a non-magnetic material. Further, as shown in the figure, the permanent magnet 5 has a total of six first magnets 4a and three second magnets 4b, which are assembled on the rod 3, but the linear actuator 1 can be driven. As long as the number of the first field 4a and the second field 4b is plural, the number is not limited to this.

  Furthermore, in this embodiment, the rod 3 is composed of the inner rod 31 and the pipes 32 and 33. However, the permanent magnet 5 may be attached to the outer periphery of the rod 3 as a cylinder. The permanent magnet 5 may be magnetized so that the poles are different between the inner circumference and the outer circumference. In any case, the S pole and the N pole appear alternately along the axial direction of the rod 3. It only has to be. Further, the flanges 35 and 36 and the flanges 36 and 37 of the inner rod 31 are divided, and the flanges 34, 35 and 36 are connected by the pipes 32 and 33, so that the rod 3 has a hollow structure. You may employ | adopt the structure accommodated by laminating | stacking a permanent magnet in it.

  In this embodiment, the outer tube 2 has a bottomed cylindrical shape, and two cylindrical cores 6a and 6b are mounted on the inner periphery. The rod 3 described above is movably inserted into the outer tube 2 and the cores 6a and 6b.

  Specifically, the outer tube 2 includes a cylindrical portion 21, a bottom portion 22, a mounting portion 23 provided at the outer end of the bottom portion 22, and a pair of annular protrusions provided on the inner periphery of the cylindrical portion 21 and projecting inwardly. Stoppers 24, 25, an inwardly projecting flange 26 provided closer to the bottom 22 than the stopper 24 on the bottom 22 side, and an inwardly projecting flange 27 provided on the inner periphery of the open end of the cylindrical part 21 The slide ring 28 is mounted on the inner periphery of the flange 26, and the slide ring 29 is mounted on the inner periphery of the flange 27.

  The outer tube 2 has the inner periphery of the slide rings 28 and 29 slidably contacted with the outer periphery of the pipes 32 and 33, which are the outer periphery of the rod 3, respectively. The first slidable contact portion 8 is configured, and the flange 27 and the slide ring 29 configure the second slidable contact portion 9.

  Therefore, in addition to the above-described third sliding contact portion 10 including the large diameter portion 38 and the slide ring 39, the rod 3 includes the first sliding contact portion 8 including the flange 26 and the slide ring 28, and the flange 27 and the slide. The second sliding contact portion 9 formed by the ring 29 is supported at a total of three locations and inserted into the outer tube 2.

  Note that the slide rings 28 and 29 are made of synthetic resin, and are in sliding contact with the outer periphery of the pipes 32 and 33 that are the outer periphery of the rod 3, respectively. The outer periphery of the pipes 32 and 33 is not gnawed. Accordingly, stick slip is less likely to occur when the first sliding contact portion 8 and the second sliding contact portion 9 slide.

  Further, the stopper 24 provided on the outer tube 2 is opposed to the left end in FIG. 1 of the large diameter portion 38 of the rod 3, and the stopper 25 is opposed to the right end in FIG. 1 of the large diameter portion 38 of the rod 3, These stoppers 24 and 25 abut against the large diameter portion 38 at the movement limit of the direction in which the rod 3 enters the outer tube 2 and the direction in which the rod 3 protrudes to the outside, and restrict further movement. The movement range of the rod 3 relative to the outer tube 2 is limited.

  Thus, the movement range of the rod 3 relative to the outer tube 2 is defined by the above structure, but within this movement range, the core 6a is always within the range of the axial length of the first field 4a of the rod 3. The core 6b is positioned within the axial length range of the second field 4b of the rod 3 and is opposed thereto.

  Further, a mounting portion 23 having a mounting hole is provided at the outer end of the bottom portion 22 of the outer tube 2, and the linear actuator 1 is not shown through the mounting portion 23 and the mounting portion 41 of the rod 3. It can be attached to external equipment.

  Each of the cores 6a and 6b includes a plurality of slots 61 that accommodate the corresponding first coil 7a and second coil 7b, and a plurality of pole teeth 62 provided between both ends and the slots 61, respectively. In this case, the cores 6a and 6b configured in this way are cylindrical and have their inner circumferences opposed to the first field 4a and the second field 4b of the rod 3, respectively. By exciting and magnetizing the pole teeth 62, the outer tube 2 and the rod 3 are relatively displaced in the axial direction by attracting and repelling the permanent magnet 5 in the first field 4 a and the second field 4 b of the rod 3. It is designed to generate thrust. The cores 6 a and 6 b do not necessarily have to be cylindrical, and the field 4 held by the rod 3 faces the cores 6 a and 6 b without forming a magnetic field over the entire circumference of the rod 3. The magnetic field may be generated in the direction, but the permanent magnet 5 is cylindrical or disc-shaped to generate a magnetic field on the outer periphery of the rod 3, and the cores 6a and 6b are formed in a cylindrical shape so as to surround the outer periphery of the rod 3. Thus, there is an advantage that the thrust does not change even if the rod 3 rotates in the circumferential direction with respect to the cores 6a and 6b. In the present embodiment, the first coil 7a and the second coil 7b are attached to the core 6a and the core 6b. However, the cores 6a and 6b are omitted, and the coils 7a and 7b are directly attached to the outer tube 2. It is also possible to wear.

  More specifically, the first coil 7a and the second coil 7b are held in the outer tube 2 while being arranged in the axial direction by being mounted in the slot 61 so as to surround the outer periphery of the rod 3. The cores 6a and 6b are provided with a total of six U phases, one V phase, and one W phase, and are arranged in the order of the U phase, the V phase, and the W phase.

  That is, the first coil 7a is provided on the outer periphery of the pipe 32 and faces the first field 4a, and the second coil 7b is provided on the outer periphery of the pipe 33 and faces the second field 4b. The stoppers 24 and 25 and the large diameter portion 38 are disposed between the first coil 7a and the second coil 7b in the axial direction, and the large diameter portion 38 of the rod 3 is moved by the stoppers 24 and 25. Interference with the cores 6a and 6b is prevented, and both the first coil 7a and the second coil 7b are protected.

  For example, the energization phase is switched based on the electrical angle of the cores 6a and 6b with respect to the rod 3, and the current amounts of the first coil 7a and the second coil 7b are controlled linearly by PWM (Pulse Width Modulation) control. The thrust of the actuator 1 and the direction in which the thrust is generated can be controlled. In controlling the linear actuator 1, it is only necessary to know the relative position of the permanent magnet 5 with respect to the core 6 a or the core 6 b, and therefore a means that can grasp the relative position of the magnetic sensor or the like may be provided. Further, the number of the first coil 7a and the second coil 7b may be set to a number suitable for the thrust generated by the linear actuator 1 and the energization method, and the number of phases may be two phases of AB. By using three phases, the fluctuation of the thrust generated by the linear actuator 1 due to the relative position between the rod 3 and the outer tube 2 can be reduced. The rod 3 and the outer tube 2 can be displaced relatively smoothly. it can.

  Now, the linear actuator 1 is configured as described above. By energizing one or both of the first coil 7a and the second coil 7b, the linear actuator 1 generates a thrust that relatively displaces the outer tube 2 and the rod 3, and these outer The tube 2 and the rod 3 can be expanded and contracted by relative displacement.

  Further, when an external force that relatively displaces the outer tube 2 and the rod 3 in the axial direction acts, energization to the first coil 7a and the second coil 7b or induction generated in the first coil 7a and the second coil 7b. An electromotive force can be used to generate a thrust that suppresses the relative displacement, thereby causing the linear actuator 1 to dampen the vibration and motion of the device due to the external force.

  Furthermore, in this linear actuator 1, the field 4 includes a first field 4a and a second field 4b, and the coil is connected to the first coil 7a and the second field 4b facing the first field 4a. If the first coil 7a and the second coil 7b are energized independently, the wire breaks in one of the first coil 7a and the second coil 7b. Even if energization is impossible, the other can be energized without any influence, so the maximum thrust can be reduced, but the thrust can continue to be generated and the operation becomes impossible. It can be avoided.

  In the linear actuator 1, the first sliding contact portion 8 and the second sliding contact portion 9 that are held by the outer tube 2 and are in sliding contact with the rod 3, and the sliding contact with the outer tube 2 that is held by the rod 3. Since the third sliding contact portion 10 is provided and the three sliding contact portions 8, 9, 10 guide the relative movement of the outer tube 2 and the rod 3, the first sliding contact portion 8 and the second sliding contact portion 8 are provided. Even if the axial distance from the sliding contact portion 9 is long, the rod 3 is pivotally supported by the intermediate third sliding contact portion 10, so that the bending of the rod 3 can be reduced.

  Further, since the bending of the rod 3 is reduced, the frictional resistance in the first sliding contact portion 8, the second sliding contact portion 9 and the third sliding contact portion 10 is also reduced, and the outer tube 2 and the rod 3 Smooth relative movement in the axial direction can be realized.

  Further, since the bending of the rod 3 is reduced, the relative positions of the field 4 and the coil in the axial direction and the radial direction are maintained almost as set, and energy loss during driving can be reduced. It becomes.

  Further, since the bending of the rod 3 is suppressed, wear in the first sliding contact portion 8, the second sliding contact portion 9 and the third sliding contact portion 10 is also suppressed, and radial play can be prevented. In addition, it is possible to prevent unevenness in the thrust generated by the linear actuator 1.

And further, in the present embodiment, since the large-diameter portion 38 forming an intermediate to the third sliding contact portion 10 of the rod 3 is provided is provided with a stopper 24, an increase in the size of the linear A actuator 1 As a result, the range of movement of the rod 3 in the axial direction can be ensured, and the rod 3 can be prevented from falling off from the outer tube 2. This is because a third sliding contact portion that slides in the middle of the rod 3 can be provided on the outer tube 2 side and a pair of stoppers can be provided on the rod 3 side, but the stopper, the first coil 7a and the second coil 7b In order to secure a moving range equivalent to that of the linear actuator 1 as described above, a space for avoiding the interference is required, and the axial length becomes long. Therefore, the third sliding contact portion 10 is formed in the middle of the rod 3. Providing the large-diameter portion 38 and providing the stoppers 24 and 25 is advantageous because the overall length can be shortened.

  In addition, in the linear actuator 1 of this embodiment, the permanent magnets 5 are accommodated in the pipes 32 and 33, and the outer periphery of the pipes 32 and 33 can be used as a sliding surface. Since the sliding of the part 8 and the second sliding contact part 9 is allowed, the first sliding contact part 8 and the second sliding contact part 9 do not need to be slid in a position where the permanent magnet 5 is avoided. The total length of 3 can be shortened.

  Further, in the above description, the first sliding contact portion 8 and the second sliding contact portion 9 are provided on the outer tube 2 side, and the third sliding contact portion 10 is provided on the rod 3 side. 8, 9 and 10 may be provided on either the outer tube 2 or the rod 3 in order to exhibit the function of reducing the bending of the rod 3.

  Further, the field 4 and the coil may be provided on either the outer tube 2 or the rod 3 in order to drive the linear actuator 1. Still further, the field 4 and the coil are configured by only one of the paired first field 4a and the first coil 7a or the paired second field 4b and the second coil 7b. Also good.

  Next, a linear actuator 70 in a modification of the embodiment shown in FIG. 2 will be described. In the linear actuator 70 according to this modified example, the stopper 24 on the bottom 22 side in the linear actuator 1 according to the embodiment described above is eliminated, and the movement range of the rod 3 entering the outer tube 2 is limited. However, the only difference is that this is done by abutting the left end of the rod 3 in FIG. 2 with the bottom 22 of the outer tube 2.

  Therefore, the linear actuator 70 in one modification is the same as the linear actuator 1 except that the movement range of the rod 3 is limited by the bottom 22 of the outer tube 2 and the end of the rod 3 instead of the stopper 24. Therefore, the same operational effects as those of the linear actuator 1 according to the above-described embodiment can be achieved.

  In addition, in the linear actuator 70 in this modified example, the installation of the stopper 24 can be omitted, and accordingly, the overall length of the outer tube 2 can be shortened, and the linear actuator 70 can be reduced in weight and size. Is possible.

  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.

1,70 Linear actuator 2 Outer tube 3 Rod 4 Field 4a First field 4b Second field 5 Permanent magnets 6a, 6b Core 7a First coil 7b Second coil 8 First sliding contact 9 Second sliding contact 10 Third sliding contact portion 21 Tube portion 22 Bottom portion 23, 41 Mounting portion 24, 25 Stopper 26, 27, 35, 36, 37 Flange 28, 29, 39 Slide ring 31 Inner rod 32, 33 Pipe 34 Shaft 35a, 37a Shoulder Part 38 large diameter part 40 spacer 61 slot 62 pole teeth

Claims (5)

An outer tube,
A rod is inserted movably into the outer tube,
A magnetic field held by a plurality of permanent magnets on one of the outer tube and the rod,
A plurality of coils which are held by the other of said outer tube and said rod so as to face the field,
A first sliding contact portion in sliding contact with the other and provided on one of said outer tube and said rod,
A second sliding contact portion in sliding contact with the other and provided on one of said outer tube and said rod,
Made from the large-diameter portion provided in the rod, and a third sliding contact portion disposed between the first sliding contact portion and the second sliding contact portion in the axial direction together with the sliding contact with the outer tube, With
To generate a thrust force for relatively moving said outer tube and said rod in the axial direction by applying a magnetic field generated from the plurality of coils with respect to the magnetic field, the outer tube and the at the three sliding contact portion A linear actuator for guiding relative movement of a rod. The above field is
A first magnetic field that is disposed between the first sliding contact portion and the third sliding contact portion,
And a second magnetic field that is disposed between the second sliding contact portion and the third sliding contact portion,
The coil is
A first coil facing the first magnetic field while being disposed between the first sliding contact portion and the third sliding contact portion,
Linear actuator according to claim 1, wherein the second coil opposite to the second magnetic field while being disposed between the second sliding contact portion and the third sliding contact portion, that Ru provided with . Provided with a stopper projecting to the inner peripheral side of the outer tube,
3. The linear actuator according to claim 1 , wherein the stopper restricts an axial movement range of the rod by abutting with the large-diameter portion . 4. The stopper consists of a pair of stoppers,
One stopper restricts the movement range of the rod to the inner side with respect to the outer tube,
Other stopper includes a linear actuator according to any one of claims 1 to 3, characterized in that to limit the range of movement of the outward side with respect to the outer tube of the rod. The outer tube has a bottomed cylindrical shape,
The bottom of the outer tube limits the range of movement of the rod inward relative to the outer tube by abutting against the end of the rod,
The linear actuator according to any one of claims 1 to 3, wherein the stopper limits a movement range of the rod to the outer side with respect to the outer tube.

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