cylindrical linear motor

Abstract

To provide a tubular linear motor in which a winding wire can be protected.SOLUTION: In order to achieve the aforementioned object, a tubular linear motor 1 according to the present invention includes a field magnet 6 in which N poles and S poles are alternately arranged in an axis direction, and an armature 2 that can move in the axis direction with respect to the field magnet 6. The armature 2 includes a tubular core 3 that is a magnetic body, a winding wire 5 wound around the core 3, and a guide bar 30 that is mounted on the core 3. The core 3 includes a cylindrical yoke 3a, a plurality of teeth 3b that are arranged on the inner circumference or outer circumference of the yoke 3a closer to the field magnet 6, so as to have an annular shape in the circumferential direction, and are arranged in the axis direction, and slots 3c which are formed of gaps between the teeth 3b and 3b and in which the winding wire 5 is mounted. The guide bar 30 is disposed over the teeth 3b on a side closer to the field magnet 6 than the winding wire 5 and along the axis direction of the core 3. Further, a plurality of the guide bars 30 are arranged in the circumferential direction of the teeth 3b, and are mounted on the core 3.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a cylindrical linear motor. [Background technology]

[0002] A cylindrical linear motor, for example, includes a cylindrical field magnet formed by stacking multiple annular permanent magnets so that south and north poles are arranged alternately in the axial direction, and an armature inserted axially within the field magnet and having U-phase, V-phase, and W-phase windings attached to slots between the core and multiple teeth arranged axially on its outer periphery.

[0003] In a cylindrical linear motor configured in this manner, by appropriately applying current to the U-phase, V-phase, and W-phase windings of the armature, attractive and repulsive forces in the axial direction are generated between the permanent magnets in the field and the armature, driving the armature or field as a mover (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-029159 Summary of the Invention [Problem to be solved by the invention]

[0005] In such cylindrical linear motors, the air gap between the field magnet and the core creates magnetic resistance, so it is desirable to make the air gap as narrow as possible to improve thrust. However, when winding the winding into the slot, the winding may extend beyond the tips of the teeth, and because the core is also attracted radially by the field magnet, there is a risk that the winding will interfere with the field magnet.

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide a cylindrical linear motor that can protect the windings. [Means for solving the problem]

[0007] In order to achieve the above object, the cylindrical linear motor of the present invention comprises a field magnet in which north and south poles are arranged alternately in the axial direction, and an armature that can move axially relative to the field magnet, the armature having a cylindrical core made of a magnetic material, a winding attached to the core, and a non-magnetic guide bar attached to the core, the core having a cylindrical yoke, a plurality of teeth arranged in a ring shape along the circumferential direction on the field magnet side of the inner or outer circumference of the yoke and lined up in the axial direction, and slots formed by the gaps between the teeth and in which the windings are attached, the guide bars being bridged along the axial direction of the core on the field magnet side of each tooth from the windings, and being arranged in multiple circumferential directions of the teeth and attached to the core.

[0008] In a cylindrical linear motor configured in this manner, the installation of guide bars on the core prevents the windings from protruding from the slots, and even if the armature is attracted to the field and becomes radially eccentric relative to the field, interference between the windings and the field or components on the field side can be prevented.

[0009] In addition, in a cylindrical linear motor, teeth are arranged in a circumferential direction and have a through hole that penetrates the wall thickness in the axial direction, and the guide bar is inserted into the through hole, which prevents the guide bar from falling off the core. [Effects of the Invention]

[0010] According to the cylindrical linear motor of the present invention, the windings can be protected. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a longitudinal sectional view of a cylindrical linear motor according to an embodiment of the present invention; [Figure 2] FIG. 2 is an enlarged side view of an armature in the cylindrical linear motor according to the embodiment. [Figure 3] 1 is a cross-sectional view of a core in a cylindrical linear motor according to an embodiment. [Figure 4]1A is a plan view of a core segment that constitutes one end of the core, FIG. 1B is a plan view of a core segment that constitutes the middle part of the core, and FIG. 1C is a plan view of a core segment that constitutes the other end of the core. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described below based on the embodiments shown in the drawings. As shown in Figure 1, a cylindrical linear motor 1 in one embodiment is configured with a cylindrical field magnet 6 in which north and south poles are alternately arranged in the axial direction, and an armature 2 that is movable in the axial direction of the field magnet 6 relative to the field magnet 6.

[0013] Each component of the cylindrical linear motor 1 will be described in detail below. In this embodiment, as shown in Figures 1 to 4, the armature 2 includes a core 3 made of a magnetic material, a winding 5, a guide bar 30 made of a non-magnetic material, and a pair of auxiliary salient poles 31 made of a magnetic material and disposed at both axial ends of the core 3. The core 3 includes a cylindrical yoke 3a, ten teeth 3b arranged annularly around the outer periphery of the yoke 3a and spaced equally apart in the axial direction, slots 3c formed by gaps between the teeth 3b and into which the winding 5 is fitted, and eight through-holes 3d that axially penetrate the wall thickness of the teeth 3b near their tips and are spaced apart in the circumferential direction on the same circumference as the teeth 3b.

[0014] As described above, the core 3 is cylindrical, and has slots 3c formed by gaps formed between each of the ten teeth 3b, into which the windings 5 ​​are attached, as shown in Fig. 1. In this embodiment, a total of nine slots 3c formed by gaps are provided between adjacent teeth 3b, 3b in Fig. 1.

[0015] Each tooth 3b is annular and, except for the teeth 3b located at both ends of the core 3, has an isosceles trapezoidal shape in which the width at the outer circumferential end is narrower in the axial direction than the width at the inner circumferential end, and both axial side surfaces are tapered surfaces inclined at an equal angle to the outer circumferential end. As shown in Fig. 1, the terminal teeth 3b have a cross-sectional shape in which the other teeth 3b are cut off along a plane perpendicular to the axis of the core 3. The cross-sectional shape of the teeth 3b may be a shape other than an isosceles trapezoid, and may be, for example, rectangular.

[0016] 2 to 4, the core 3 is formed by stacking a plurality of annular core segments C1, C2, and C3 that are divided in the axial direction so that each segment has one tooth 3b. Specifically, the core 3 is composed of one core segment C1 corresponding to one end of the core 3, eight core segments C2, and one core segment C3 corresponding to the other end of the core 3.

[0017] The core segment C1 corresponding to one end of the core 3 is annular and includes an annular yoke portion 40 corresponding to the yoke 3a of the core 3, teeth 3b provided on the outer periphery of the yoke portion 40, eight through holes 3d axially penetrating the outer periphery of the teeth 3b near the tips of the teeth 3b and arranged at equal intervals along the circumferential direction on the same circumference as the teeth 3b, six positioning holes 40a axially penetrating the yoke portion 40, and slits 41 leading from the outer periphery of the teeth 3b to the inner periphery of the yoke portion 40. The core segment C1 has a C-shape in plan view due to the inclusion of the slits 41. The axial length of the yoke portion 40 in the core segment C1 is the same as the axial length of the root portions of the teeth 3b. Since the teeth 3b in the core segment C1 are located at the ends of the core 3, the teeth 3b in the core segment C2 corresponding to the middle portion of the core 3 have a cross-sectional shape obtained by cutting off the teeth 3b along a plane perpendicular to the axis of the core 3. Therefore, one end of the core segment C1 is flat, with the end faces of the teeth 3b and the yoke portion 40 being flush with each other.

[0018] Furthermore, each core segment C2 corresponding to a portion other than both ends of the core 3 includes an annular yoke portion 42 corresponding to the yoke 3a of the core 3, teeth 3b offset toward the outer periphery of the yoke portion 42, eight through holes 3d axially penetrating near the outer periphery that constitutes the tips of the teeth 3b and arranged at equal intervals along the circumferential direction on the same circumference as the teeth 3b, six positioning holes 42a axially penetrating the yoke portion 42, and slits 43 leading from the outer periphery of the teeth 3b to the inner periphery of the yoke portion 42. The core segment C2 is C-shaped in plan view because of the slits 43. The axial length of the yoke portion 42 of the core segment C2 is longer than the axial length of the base portions of the teeth 3b, and the teeth 3b are offset toward one end of the yoke portion 42, so that one end of the base portions of the teeth 3b and one axial end of the yoke portion 42 are flush with each other.

[0019] Furthermore, the core segment C3 corresponding to the other end of the core 3 includes an annular yoke portion 44 corresponding to the yoke 3a of the core 3, teeth 3b offset toward the outer periphery of the yoke portion 44, eight through holes 3d axially penetrating near the outer periphery that is the tip of the teeth 3b and arranged at equal intervals along the circumferential direction on the same circumference as the teeth 3b, six positioning holes 44a axially penetrating the yoke portion 44, and slits 45 leading from the outer periphery of the teeth 3b to the inner periphery of the yoke portion 44. The core segment C3 is C-shaped in plan view because of the slits 45. The axial length of the yoke portion 44 of the core segment C3 is longer than the axial length of the base portions of the teeth 3b, and the teeth 3b are offset toward one end of the yoke portion 42, so that one end of the base portions of the teeth 3b and one axial end of the yoke portion 44 are flush with each other. Since the teeth 3b of the core segment C3 are located at the ends of the core 3, the teeth 3b of the core segment C2, which corresponds to the middle part of the core 3, have a cross-sectional shape obtained by cutting off the teeth 3b along a plane perpendicular to the axis of the core 3. Therefore, one end of the core segment C3 forms a flat surface where the end faces of the teeth 3b and the end face of the yoke portion 44 are flush with each other.

[0020] The core 3 is formed by stacking eight core segments C2 and C3 on the core segment C1 corresponding to the end of the core 3 configured in this way. The through hole 3d, positioning holes 40a, 42a, 44a, and slits 41, 43, 45 in the core segments C1, C2, and C3 are located in the same positions relative to the teeth 3b, and when the core segments C1, C2, and C3 are stacked such that the positioning hole 40a in the core segment C1, the positioning hole 42a in the core segment C2, and the positioning hole 44a in the core segment C3 are aligned in a straight line in the axial direction when the core 3 is viewed axially, the through holes 3d in the teeth 3b of the core segments C1, C2, and C3 are also aligned in a straight line in the axial direction, and the slits 41, 43, 45 are also aligned in a straight line in the axial direction. Then, when the core 3 is assembled, the eight through-holes 3d are arranged in a straight line in the axial direction, and the slits 41, 43, 45 are arranged in a straight line in the axial direction.

[0021] When stacking the core segments C1, C2, and C3, positioning pins (not shown) can be inserted into at least two of the positioning holes 40a, 42a, and 44a, allowing the core segments C1, C2, and C3 to be positioned using the pins as references, and the core segments C1, C2, and C3 can be easily stacked while aligned in the appropriate positions to assemble the core 3.

[0022] When the core segments C1, C2, and C3 configured in this manner are stacked to form the core 3, the axial lengths of the yoke portions 42, 44 of the core segments C2, C3 are longer than the axial lengths of the root portions of the teeth 3b, and the teeth 3b are positioned offset toward one end of the yoke portions 42, 44. This results in slots 3c being formed between the teeth 3b of the core segments C1, C2, between the teeth 3b of the core segments C2, C2, and between the teeth 3b of the core segments C2, C3. A winding 5 is wound around and installed in these slots 3c. The winding 5 is composed of three phases: a U-phase winding, a V-phase winding, and a W-phase winding.

[0023] To attach the winding 5 to the core 3 configured in this manner, for example, the winding 5 is first attached to the core segments C2 and C3, and lead wires (not shown) are passed through the slits 43 and 45. The core segments C1, C2, and C3 assembled with the winding 5 in this manner are then stacked while pins are inserted into the positioning holes 40a, 42a, and 44a. The lead wires (not shown) are connected to the winding 5 of the same phase through the slits 41, 43, and 45 stacked in the core segments C1, C2, and C3 with the winding 5 attached. In the process of stacking these core segments C1, C2, and C3, pins are inserted into at least two of the six positioning holes 40a, 42a, and 44a, as described above. By inserting the pins in this manner, the core segments C1, C2, and C3 are positioned circumferentially, which makes it very easy to align the through holes 3d and the slits 41, 43, and 45, greatly facilitating the manufacturing process of the core 3. The core segments C1, C2, and C3 are bonded together to form a single unit. The pins can be removed once the assembly of the core 3 is complete. Furthermore, because the core 3 is composed of the core segments C1, C2, and C3, drilling the through holes 3d in the teeth 3b is easy, and the core 3 having the through holes 3d in the teeth 3b of the core 3 can be manufactured easily. However, the core 3 may be formed from a single part rather than by stacking the core segments C1, C2, and C3. Furthermore, when the core 3 is formed by stacking core segments, the configuration of the core segments is not limited to the configuration described above. For example, the design of the division position in the axial direction of the core 3 may be changed to form the core segments so that the teeth 3b are positioned at the axial center of the outer periphery of the yoke portion, or one core segment may have multiple teeth 3b.

[0024] Although the slits 41, 43, and 45 lead to the inner periphery of the core segments C1, C2, and C3, they may be formed partway along the radial direction of the yoke portions 40, 42, and 44 and not lead to the inner periphery of the core segments C1, C2, and C3. However, if the slits 41, 43, and 45 lead to the inner periphery of the core segments C1, C2, and C3, when the core 3 is formed, the slits 41, 43, and 45 will penetrate to the inner periphery of the core 3. Therefore, by providing an annular gap between the core 3 and the rod 11, the lead wires can be arranged on the inner periphery of the core 3, which makes it easier to separate and insulate the lead wires connected to the windings 5 ​​of different phases.

[0025] Furthermore, since the winding 5 is composed of three-phase windings of U, V, and W phases, in order to improve the insulation between each phase, it is possible to provide holes that can communicate with the slits 41, 43, 45 of adjacent core segments C1, C2, and C3 and that connect the slots 3c in which windings 5 ​​of the same phase are installed, so that the lead wires for each phase do not coexist in the same slits 41, 43, and 45, thereby avoiding the mixing of lead wires of different phases.

[0026] The guide bars 30 are made of a non-magnetic material and formed into a cylindrical shape, and are inserted into the through holes 3d of the core 3 that are arranged in a straight line in the axial direction. Looking at the core 3 from the axial direction, eight through holes 3d are provided at equal intervals in the circumferential direction relative to the teeth 3b, and each through hole 3d is arranged in a straight line in the axial direction, so in this example, eight guide bars 30 are provided on the core 3 at equal intervals in the circumferential direction and span across each tooth 3b along the axial direction.

[0027] The through hole 3d is provided on the outer periphery of the winding 5 mounted in the slot 3c of the core 3 in the tooth 3b, closer to the field 6 than the outer periphery of the winding 5, and when the guide bar 30 is mounted on the core 3, it is positioned closer to the field 6 than the winding 5 with respect to the core 3.

[0028] There are no restrictions on the material of the guide bar 30 as long as it is non-magnetic, but since it becomes very hot when current is applied to the windings 5, it is preferable that the guide bar 30 be made of a non-magnetic metal.

[0029] The cross-sectional shape of the guide bar 30 may be other than circular. However, since the guide bar 30 is provided to protect the winding 5 by preventing it from protruding from the slot 3c, a circular shape is advantageous because it is less likely to damage the winding 5 when it comes into contact with the guide bar 30. Therefore, the cross-sectional shape of the guide bar 30 is preferably a shape without corners, such as a circle. The guide bar 30 may be solid or hollow, but preferably has sufficient rigidity to prevent bending without tension when inserted into the through-hole 3d, and to prevent deformation even when the winding 5 comes into contact with it, thereby preventing the winding 5 from protruding from the slot 3c. However, the guide bar 30 may be made of wire or the like and stiffened by tension, so that the guide bar 30 does not deform even when the winding 5 comes into contact with it, preventing the winding 5 from protruding from the slot 3c. Furthermore, since the guide bar 30 is a non-magnetic material, it does not form a magnetic circuit even when attached to the core 3, does not affect the magnetic field of the field 6, or the magnetic field when current is applied to the winding 5, and there is no need to worry about it being attracted to the field 6 and deforming.

[0030] In this embodiment, the guide bar 30 is inserted into the through-holes 3d formed in the teeth 3b, so that even if a force that would cause the guide bar 30 to fall off from the core 3 is applied, the guide bar 30 can be prevented from falling off. When installing the guide bar 30 in the core 3, it is also possible to form grooves in each tooth 3b of the core 3 that open from the outer periphery and are aligned in a straight line in the axial direction, and then insert the guide bar 30 into the grooves and fix the guide bar 30 to the core 3 by adhesive or the like. Whether the through-holes 3d are formed in the teeth 3b or the grooves are formed, the guide bar 30 is recessed toward the yoke 3a from the outer periphery, which is the tip of the tooth 3b, and does not protrude toward the field 6.

[0031] In this embodiment, eight through holes 3d are formed in each tooth 3b at equal intervals in the circumferential direction, and a guide bar 30 is inserted into each through hole 3d, so that eight guide bars 30 are provided on the core 3, but the number of guide bars 30 provided on the core 3 may be set to a number other than eight, as long as it is plural and can prevent the windings 5 ​​from protruding from the slots 3c. Furthermore, the guide bars 30 do not have to be arranged at equal intervals in the circumferential direction of the teeth 3b, as long as it can prevent the windings 5 ​​from protruding from the slots 3c, but if three or more guide bars 30 are arranged at equal intervals in the circumferential direction of the teeth 3b, the weight balance in the circumferential direction of the core 3 is improved, and smooth extension and contraction of the cylindrical linear motor 1 can be ensured.

[0032] The pair of auxiliary salient poles 31 are made of a magnetic material, are annular, and abut against both ends of the core 3, sandwiching the core 3 therebetween, and are provided with R-shaped chamfered portions 31a on the outer periphery on the field side, axially opposite the core 3. The provision of the auxiliary salient poles 31 smooths the change in magnetic flux at both axial ends of the core 3, and the cogging thrust of the cylindrical linear motor 1 can be reduced.

[0033] As described above, in the cylindrical linear motor 1 of this embodiment, the auxiliary salient poles 31 abut against the teeth 3b at both ends of the core 3 and block the through holes 3d of the end teeth 3b, preventing the guide bar 30 from falling off the core 3 without adhesively bonding the guide bar 30 to the teeth 3b. Note that the installation of the auxiliary salient poles 31 is optional and can be omitted if unnecessary, or they can be provided integrally and inseparably at both ends of the core 3. Note that if the auxiliary salient poles 31 are not provided, the guide bar 30 inserted into the through holes 3d can be fixed to the core 3 by adhesive, or the core 3 can be sandwiched between the sliders 21b and 25 described below. When the core 3 is sandwiched between the sliders 21b and 25, the sliders 21b and 25 can prevent the guide bar 30 from falling off the through holes 3d without adhesive.

[0034] In this way, the armature 2, which is made up of the core 3, winding 5, guide bar 30, and auxiliary salient pole 31, is attached to the outer periphery of the tip of the rod 11, which is made of a non-magnetic material and serves as the output shaft. The rod 11 includes a cylindrical first rod 20 and a cylindrical second rod 21, which has the core 3 attached to its outer periphery and is screwed onto the inner periphery of the first rod 20.

[0035] The first rod 20 is cylindrical and includes a rod body 22 having screw portions 22a and 22b on the outer periphery at the left end in FIG. 1 and on the inner periphery at the right end in FIG. 1, respectively, and a rod cap 23 having a bracket 23a for attaching the cylindrical linear motor 1 to equipment and screwed onto the screw portion 22a at the left end in FIG. 1 of the rod body 22 to close the left end of the rod body 22.

[0036] An annular slider 25 is fitted to the outer periphery of the right end of the rod main body 22 in FIG. 1. The slider 25 includes a sliding contact portion 25a that slides against the inner periphery of a cylindrical portion 9b (described later), a small-diameter portion 25b that is provided on the base end side of the rod 11, which is to the left of the sliding contact portion 25a in FIG. 1, and has an outer diameter smaller than that of the sliding contact portion 25a, an annular groove 25c that is provided circumferentially on the outer periphery of the small-diameter portion 25b, and a flange 25d that is provided on the inner periphery of the right end in FIG. 1. A rubber seal ring 26 serving as an elastic body is fitted in the annular groove 25c of the slider 25. The inner diameter of the flange 25d is equal to or larger than the inner diameter of the rod main body 22 but smaller than the outer diameter of the rod main body 22. When the slider 25 is fitted to the rod main body 22, the flange 25d abuts against the right end surface of the rod main body 22 in FIG. 1.

[0037] The second rod 21 includes a cylindrical armature retaining tube 21a on whose outer periphery the armature 2 is attached, and an annular slider 21b provided on the outer periphery of the tip of the armature retaining tube 21a, which is the right end in FIG. 1. A threaded portion 21c is provided on the outer periphery of the base end of the armature retaining tube 21a, which is the left end in FIG. 1. The inner periphery of the base end of the armature retaining tube 21a is provided with a large inner diameter portion 21d whose inner diameter is larger than that of other portions. When the base end of the armature retaining tube 21a is inserted into the inner periphery of the rod main body 22 of the first rod 20 at the right end in FIG. 1 and the threaded portion 21c is screwed into the threaded portion 22b, the first rod 20 and the second rod 21 are connected. In this manner, in this embodiment, the rod 11 is cylindrical and made up of the first rod 20 and the second rod 21.

[0038] The armature 2 is fitted onto the outer periphery of the armature retaining cylinder 21a of the second rod 21. The outer diameter of the armature retaining cylinder 21a is smaller than the outer diameter of the rod main body 22 of the first rod 20. Therefore, when the second rod 21, on which the armature 2 is mounted, is connected to the first rod 20, on which the slider 25 is mounted, in the manner described above, the armature 2 and the slider 25 are sandwiched and fixed between the right end of the first rod 20 in FIG. 1 and the slider 21b of the second rod 21. When the armature 2 is mounted on the rod 11 in this manner, the armature 2 is fixed to the rod 11 in a manner sandwiched between the slider 21b and the slider 25. Note that, although the armature 2 is configured to have only a single core 3 in this embodiment, it may be configured to have multiple cores 3 to improve thrust, etc.

[0039] Next, the rod 11 is provided with a cover 17 that covers the outer periphery of the rod 11 and forms a gap G. Specifically, the cover 17 is cylindrical, and is attached to the rod 11 with one end fitted onto the outer periphery of an annular cover end 18 provided on the outer periphery of the rod 11 and the other end fitted onto the outer periphery of the small diameter portion 25b of the slider 25.

[0040] Lead wires L that connect the windings 5 ​​of each phase attached to the core 3 to an external drive circuit (not shown) are housed in the gap G between the cover 17 and the rod 11, and the wiring work between the windings 5 ​​and the lead wires L can be performed with the cover 17 removed, making the assembly work of the cylindrical linear motor 1 easier.

[0041] On the other hand, in this embodiment, the stator is configured to include a field 6 made up of a cylindrical laminated magnet body 10 and a back yoke 8 made of a cylindrical magnetic material attached to the outer periphery of the laminated magnet body 10, a cylindrical inner tube 9 made of a non-magnetic material inserted into the inner periphery of the laminated magnet body 10, and a cylindrical barrel 7 made of a non-magnetic material into which the inner tube 9 and the field 6 are inserted.

[0042] The barrel 7 is made of a non-magnetic material and has a threaded portion 7a provided on the inner periphery of the open end on the left side in FIG. 1 and a threaded portion 7b provided on the outer periphery of the open end on the right side in FIG. 1. A bottom cap 12 is screwed onto the outer periphery of the open end on the right side in FIG. 1 of the barrel 7, closing the open end on the right side in FIG. 1. The bottom cap 12 is cylindrical with a bottom 12a and a tubular portion 12b, and is attached to the barrel 7 by screwing the tubular portion 12b onto the outer periphery of the barrel 7. A bracket 12c is provided on the tubular portion 12b of the bottom cap 12, allowing the cylindrical linear motor 1 to be attached to a device. The bottom 12a of the bottom cap 12 faces the right end of the field magnet 6 in FIG. 1.

[0043] The inner tube 9 is made of a non-magnetic material and is configured to include an annular head portion 9a that is attached by screwing to the open end at the left end in Fig. 1 of the barrel 7, and a tubular portion 9b that is thinner in thickness than the head portion 9a and extends from the inner periphery of the right end in Fig. 1 of the head portion 9a and is inserted into the inner periphery of the field magnet 6. Therefore, the right end in Fig. 1 of the head portion 9a of the inner tube 9 faces the left end in Fig. 1 of the field magnet 6 that is arranged on the outer periphery of the tubular portion 9b.

[0044] The inner tube 9 also has a curved surface 9c at the boundary between the right end of the head portion 9a in Figure 1 and the cylindrical portion 9b, so that even if an axial force acts only on the head portion 9a, stress does not concentrate at the boundary between the head portion 9a and the cylindrical portion 9b. To avoid such stress concentration, a tapered surface may be provided at the boundary between the head portion 9a and the cylindrical portion 9b.

[0045] The field 6 is configured to include a laminated magnet body 10 formed of a plurality of annular permanent magnets 10a serving as main magnetic poles and a plurality of annular permanent magnets 10b serving as sub-magnetic poles, which are alternately stacked in the axial direction and inserted, and a cylindrical back yoke 8 that fits onto the outer periphery of the laminated magnet body 10 and is bonded to and fixed to the outer periphery of the laminated magnet body 10.

[0046] The laminated magnet body 10 is composed of multiple annular permanent magnets 10a that serve as main poles and multiple annular permanent magnets 10b that serve as sub-pole poles, stacked alternately in the axial direction. The permanent magnets 10a and 10b are stacked with an adhesive between them to prevent them from scattering. Note that the triangular marks on the main pole permanent magnets 10a and sub-pole permanent magnets 10b in FIG. 1 indicate the magnetization direction, with the main pole permanent magnets 10a being magnetized radially and the sub-pole permanent magnets 10b being magnetized axially. The main pole permanent magnets 10a and sub-pole permanent magnets 10b are arranged in a Halbach array, with south and north poles alternating in the axial direction on the inner periphery of the field magnet 6.

[0047] Furthermore, in the cylindrical linear motor 1 of this embodiment, the axial length of the permanent magnet 10a of the main magnetic pole is longer than the axial length of the permanent magnet 10b of the sub-pole. In this way, if the axial length of the permanent magnet 10a of the main magnetic pole is increased, the magnetic resistance between the permanent magnet 10a of the main magnetic pole and the core 3 can be reduced, and the magnetic field acting on the core 3 can be increased, thereby improving the thrust of the cylindrical linear motor 1. In this embodiment, the axial length of the permanent magnet 10a of the main magnetic pole is longer than the axial length of the permanent magnet 10b of the sub-pole, but this is not limiting and the axial lengths of the two can be set as desired by design.

[0048] Furthermore, in the cylindrical linear motor 1 of the present invention, a back yoke 8 is provided around the permanent magnets 10a and 10b. Without the back yoke 8, shortening the axial length of the permanent magnets 10b of the sub-pole increases magnetic resistance outside the permanent magnets 10a of the main pole at the axial center, reducing the field flux. This reduces the degree of improvement in thrust of the cylindrical linear motor 1 when the axial length of the permanent magnets 10a of the main pole is increased. In contrast, providing a back yoke 8 around the permanent magnets 10a and 10b ensures a magnetic path with low magnetic resistance, thereby suppressing the increase in magnetic resistance caused by shortening the axial length of the permanent magnets 10b of the sub-pole. Therefore, making the axial length of the permanent magnets 10a of the main pole longer than that of the permanent magnets 10b of the sub-pole and providing a cylindrical back yoke 8 around the permanent magnets 10a and 10b can significantly improve the thrust of the cylindrical linear motor 1. In this way, providing the back yoke 8 can suppress an increase in magnetic reluctance, but it is also possible to omit the back yoke 8. The thickness of the back yoke 8 may be set to a thickness suitable for suppressing an increase in the external magnetic reluctance of the permanent magnets 10a of the main poles. If the axial length of the back yoke 8 is longer than the overall length of the laminated magnet body 10, the magnetic field lines at the ends of the laminated magnet body 10 will not leak into the atmosphere, preventing a decrease in thrust of the cylindrical linear motor 1. In this way, the axial length of the back yoke 8 can be made longer than the axial length of the laminated magnet body 10 by making the axial length of the back yoke 8 longer than the axial length of the laminated magnet body 10. Furthermore, in this embodiment, the laminated magnet body 10 is composed of permanent magnets 10a and 10b stacked in a Halbach array, but it may also be composed of annular permanent magnets magnetized in the radial direction and having a north pole on their inner periphery, and annular permanent magnets magnetized in the radial direction and having a south pole on their inner periphery, stacked in that order.

[0049] The armature 2 is inserted inside the field magnet 6 configured in this manner so as to be movable in the axial direction, and the field magnet 6 applies a magnetic field to the core 3. Note that the field magnet 6 only needs to apply a magnetic field within the movable range of the core 3, so the installation range of the laminated magnet body 10 can be determined according to the movable range of the core 3. Therefore, it is not necessary to install permanent magnets 10a, 10b in the area of ​​the annular gap between the barrel 7 and the cylindrical portion 9b that does not face the core 3.

[0050] An annular head-side spacer 50, the field magnet 6, and an annular end-side spacer 51 are housed between the outer periphery of the cylindrical portion 9b and the inner periphery of the barrel 7. The head-side spacer 50 is cylindrical and has a shape in which the outer diameter on the anti-field magnet side, which is the left side in FIG. 1, is larger than the outer diameter on the field magnet side, which is the right side in FIG. 1, and is equipped with a large-diameter portion 50a and a small-diameter portion 50b, with the left end of the large-diameter portion 50a in FIG. 1 abutting against the right end face in FIG. 1 of the head portion 9a of the inner tube 9, and the right end of the small-diameter portion 50b in FIG. 1 abutting against the left end of the field magnet 6.

[0051] The end-side spacer 51 is cylindrical and has a shape in which the outer diameter on the anti-field side, which is the right side in FIG. 1, is larger than the outer diameter on the field side, which is the left side in FIG. 1, and is provided with a large-diameter portion 51a and a small-diameter portion 51b, with the right end of the large-diameter portion 51a in FIG. 1 abutting against the left end surface, in FIG. 1, of the bottom portion 12a of the bottom cap 12, and the left end of the small-diameter portion 51b in FIG. 1 abutting against the right end 6b of the field 6.

[0052] 1, an annular head spacer 50, a field magnet 6, and an annular end spacer 51 are fitted onto the outer periphery of the cylindrical portion 9b, and after the head portion 9a of the inner tube 9 is screwed into the barrel 7, a bottom cap 12 is attached to the right end of the barrel 7 in FIG. 1, whereby the head spacer 50, laminated magnet body 10, and end spacer 51 are sandwiched between the head portion 9a of the inner tube 9 and the bottom portion 12a of the bottom cap 12, and the laminated magnet body 10 is fixed to the inner periphery of the barrel 7. Note that the back yoke 8 attached to the outer periphery of the laminated magnet body 10 is not sandwiched axially between the head portion 9a and the bottom cap 12, but is adhered to the laminated magnet body 10 and does not move within the barrel 7.

[0053] In addition, an annular sealing member 28 is provided on the inner circumference of the head portion 9a, which is in sliding contact with the outer circumference of the cover 17 that covers the outer circumference of the first rod 20, preventing dust, water, etc. from entering the cylindrical linear motor 1.

[0054] A rod 11 with an armature 2 attached thereto is inserted into the inner tube 9 so as to be movable in the axial direction, and sliders 21b and 25 slide against the inner periphery of the cylindrical portion 9b to guide the movement of the armature 2 in the axial direction.

[0055] The cylindrical portion 9b forms a gap between the outer periphery of the core 3 and the inner periphery of each permanent magnet 10a, 10b, and also serves to guide the axial movement of the core 3 in cooperation with the sliders 21b, 25. In this embodiment, the armature 2 is configured to have only a single core 3, but if the armature has multiple cores 3, sliders that come into sliding contact with the inner periphery of the cylindrical portion 9b may be provided not only at both axial ends of the armature 2 but also between the cores 3. In this embodiment, the inner tube 9 with which the sliders 21b, 25 come into sliding contact is provided to guide the axial movement of the armature 2 relative to the field magnet 6, but the inner tube 9 may be eliminated if the axial movement of the armature 2 is guided by other components.

[0056] Furthermore, a guide rod 16 is attached to the inner periphery of the bottom 12a of the bottom cap 12. The guide rod 16 has a base end 16a fixed to the inner periphery of the bottom 12a, and a guide portion 16b extending from the base end 16a toward the rod 11 and slidably inserted into the rod 11, and is always in sliding contact with the inner periphery of the rod 11 even when the cylindrical linear motor 1 extends or retracts. More specifically, the guide portion 16b of the guide rod 16 is slidably inserted toward the tip side of the large inner diameter portion 21d of the second rod 21.

[0057] In this way, in the cylindrical linear motor 1 of this embodiment, the guide rod 16 is in sliding contact with the inner circumference of the rod 11, and the sliders 21b, 25 are in sliding contact with the cylindrical portion 9b, so the armature 2 can move smoothly in the axial direction together with the rod 11 without becoming eccentric relative to the field 6, but the guide rod 16 may be eliminated.

[0058] Furthermore, in the cylindrical linear motor 1 configured in this manner, the cylindrical portion 9b, which guides the axial movement of the armature 2 and prevents the armature 2 from becoming eccentric relative to the field magnet 6, is integrally structured with the head portion 9a, so distortion is less likely to occur in the cylindrical portion 9b and the head portion 9a, and the sliders 21b and 25 can slide smoothly on the inner circumference of the cylindrical portion 9b, allowing it to expand and contract smoothly.

[0059] The cylindrical linear motor 1 is driven by a controller that detects the position of the rod 11 relative to the field 6 using a stroke sensor (not shown), grasps the electrical angle of the core 3 relative to the field 6, switches the energized phase, and controls the amount of current in each winding 5 using PWM control to control the thrust and the movement direction of the armature 2 in the cylindrical linear motor 1. Note that the control method of the controller described above is one example and is not limited to this. Furthermore, when an external force acts to relatively displace the armature 2 and the field 6 in the axial direction, a thrust that suppresses the relative displacement is generated by energizing the windings 5 ​​or by induced electromotive force generated in the windings 5, allowing the cylindrical linear motor 1 to damp the vibration and movement of the equipment caused by the external force, and also enabling energy regeneration to generate electric power from the external force.

[0060] As described above, the cylindrical linear motor 1 of the present invention comprises a field 6 in which north and south poles are arranged alternately in the axial direction, and an armature 2 that can move axially relative to the field 6. The armature 2 has a cylindrical core 3 made of a magnetic material, a winding 5 attached to the core 3, and a non-magnetic guide bar 30 attached to the core 3. The core 3 has a cylindrical yoke 3a, a plurality of teeth 3b that are arranged in a ring shape around the outer periphery of the yoke 3a and lined up in the axial direction, and slots 3c formed by the gaps between the teeth 3b, 3b and in which the winding 5 is attached. The guide bars 30 are bridged along the axial direction of the core 3 on the field 6 side of the windings 5 ​​and are attached to the core 3 with multiple guide bars 30 arranged circumferentially around the teeth 3b.

[0061] In the cylindrical linear motor 1 configured in this manner, the guide bar 30 provided on the core 3 prevents the windings 5 ​​from protruding from the slots 3c. Therefore, even if the armature 2 is attracted to the field 6 and becomes radially eccentric relative to the field 6, the windings 5 ​​can be prevented from contacting the inner tube 9 provided on the field 6 side, preventing damage to the windings 5. Note that if the inner tube 9 is eliminated, the windings 5 ​​can be prevented from contacting the field 6 and preventing damage to the windings 5, even if the armature 2 is attracted to the field 6 and becomes radially eccentric relative to the field 6. In this way, with the cylindrical linear motor 1 of this embodiment, the windings 5 ​​can be protected by providing the guide bar 30 on the core 3.

[0062] Furthermore, according to the cylindrical linear motor 1 of this embodiment, the windings 5 ​​can be protected by the guide bar 30, so the gap between the field 6 and the armature 2 can be narrowed, thereby improving the thrust.

[0063] Furthermore, in the cylindrical linear motor 1 of this embodiment, the teeth 3b are arranged in a circumferential direction and have a through hole 3d that penetrates the wall thickness in the axial direction, and the guide bar 30 is inserted into the through hole 3d, which can prevent the guide bar 30 from falling off the core 3.

[0064] In the cylindrical linear motor 1 of this embodiment, the armature 2 is inserted inside the field 6, but in the case of a cylindrical linear motor with a structure in which the field is inserted inside the armature, a plurality of teeth are provided in a ring shape along the circumferential direction on the inner periphery of the core, which is the field side of the yoke, and are arranged in the axial direction. Therefore, in a cylindrical linear motor with a structure in which the field is inserted inside the armature, the guide bars are simply attached to the core by spanning each of the teeth along the axial direction of the core, on the inner periphery, which is closer to the field than the windings, and arranged in multiple positions circumferentially of the teeth. This prevents interference between the windings and the field or components on the field side, thereby protecting the windings.

[0065] Although the preferred embodiment of the present invention has been described in detail above, modifications, variations and changes can be made thereto without departing from the scope of the appended claims. [Explanation of symbols]

[0066] 1... Cylindrical linear motor, 2... Armature, 3... Core, 3a... Yoke, 3b... Teeth, 3c... Slot, 3d... Through hole, 5... Winding, 6... Field, 30... Guide bar

Claims

1. a field magnet in which north and south poles are alternately arranged in the axial direction; an armature that is movable in the axial direction relative to the field magnet; The armature includes: a cylindrical core made of a magnetic material; a winding attached to the core; a non-magnetic guide bar attached to the core; The core is A cylindrical yoke; a plurality of teeth arranged annularly along the circumferential direction on the field side of the inner or outer periphery of the yoke and aligned in the axial direction; a slot formed by a gap between the teeth and into which the winding is fitted, The guide bars are bridged along the axial direction of the core on the field side of the windings on each of the teeth, and a plurality of the guide bars are arranged in the circumferential direction of the teeth and attached to the core. A cylindrical linear motor characterized by:

2. The teeth have through holes that are arranged in a circumferential direction and penetrate the wall thickness in an axial direction, The guide bar is inserted into the through hole.

2. The cylindrical linear motor according to claim 1.

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