Cylindrical linear motor

Abstract

To provide a cylindrical linear motor that can be easily assembled. [Solution] The cylindrical linear motor 1 comprises a field 2 having a cylindrical sleeve 3 made of a soft magnetic material and a plurality of permanent magnets 4 mounted on the sleeve 3, a rod 5 inserted into the inside of the sleeve 3 so as to be movable in the axial direction and protruding from one end of the sleeve 3 to the outside of the sleeve 3, an armature 6 mounted on the outer circumference of the rod 5 and inserted into the sleeve 3, and a plurality of sliders 7, 8 mounted on the outer circumference of the rod 5 on both sides in the axial direction of the armature 6 and slidingly contacting the inner circumference of the sleeve 3, and the sleeve 3 is provided with a coupling mechanism 3d at the other end.

Description

Technical Field

[0001] The present invention relates to a tubular linear motor.

Background Art

[0002] Generally, a linear motor includes a field magnet formed by a shaft body and annular yokes and annular permanent magnets alternately mounted on the outer periphery of the shaft body, and an armature having a cylindrical core and windings mounted on the core, with the field magnet axially movably inserted inward of the core (see, for example, Patent Document 1).

[0003] Also, in a conventional linear motor, there are provided a cylindrical body for accommodating the field magnet and two annular bearings fixed to both ends of the cylindrical body by welding, and both ends of the shaft body in the field magnet are supported by the two bearings. Then, by inserting the field magnet into the cylindrical body in advance and welding the bearings for supporting the shaft body to both ends of the cylindrical body respectively, a mover unit including the field magnet is created, and the linear motor is manufactured by inserting the mover unit into a cylindrical armature (see, for example, Patent Document 1). On the armature side, there is provided a case body having holes for allowing the insertion of the bearings at both ends of the mover unit to support both ends of the mover unit. The conventional linear motor adopts a structure in which the cylindrical body of the mover unit is supported by the armature and the field magnet inside the cylindrical body is supported by the bearings on both sides of the cylindrical body.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In this type of linear motor, the movable element unit is assembled in advance and then inserted into the armature, which makes it easy to align the armature and the field. However, when inserting the movable element unit into the armature, there is no support for the unit, so the permanent magnets in the field attract to the core of the armature, which makes assembly difficult.

[0006] Therefore, the present invention aims to provide a cylindrical linear motor that can be easily assembled. [Means for solving the problem]

[0007] To achieve the above objective, the cylindrical linear motor of the present invention comprises a field having a cylindrical sleeve made of a soft magnetic material and a plurality of permanent magnets mounted in the sleeve, a rod inserted into the inside of the sleeve so as to be movable in the axial direction and protruding from one end of the sleeve to the outside of the sleeve, an armature mounted on the outer circumference of the rod and inserted into the sleeve, and a plurality of sliders mounted on the outer circumference of the rod on both sides in the axial direction of the armature and slidingly in contact with the inner circumference of the sleeve, the sleeve having a coupling mechanism at the other end.

[0008] With this cylindrical linear motor configuration, the sleeve is equipped with a coupling mechanism at the other end, and the assembly jig used in the process of inserting the armature and slider into the sleeve can be connected to the sleeve using the coupling mechanism. This makes it less susceptible to the effects of magnetic attraction, facilitates the insertion of the rod, armature, and slider into the sleeve, and reduces the workload on the operator.

[0009] Furthermore, the cylindrical linear motor may include a barrel that is bottomed and made of a non-magnetic material to house the field magnet, and the sleeve may be housed in the barrel with its other end facing the bottom of the barrel, without being connected to any coupling mechanism.

[0010] With this cylindrical linear motor configuration, the sleeve is housed inside the barrel with the other end facing the bottom of the barrel, rather than the end where the rod protrudes. This protects the coupling mechanism from the barrel, and when the armature is removed from the sleeve during maintenance and then reinserted, the assembly jig, which requires high precision for attachment to the sleeve, can be properly connected, thus not compromising the workability during maintenance. [Effects of the Invention]

[0011] The cylindrical linear motor of the present invention can be easily assembled. [Brief explanation of the drawing]

[0012] [Figure 1] This is a longitudinal cross-sectional view of a cylindrical linear motor in one embodiment. [Figure 2] This figure shows the assembly process of a cylindrical linear motor according to one embodiment. [Modes for carrying out the invention]

[0013] The present invention will be described below based on the embodiments shown in the figures. In one embodiment, the cylindrical linear motor 1, as shown in Figure 1, comprises a field 2 having a cylindrical sleeve 3 and a plurality of permanent magnets 4 mounted on the sleeve 3, a rod 5 inserted into the inside of the sleeve 3 so as to be movable in the axial direction, an armature 6 mounted on the outer circumference of the rod 5 and inserted into the sleeve 3, and a plurality of sliders 7, 8 mounted on the outer circumference of the rod 5.

[0014] The following describes the various parts of the cylindrical linear motor 1. The field magnet 2 is composed of a cylindrical sleeve 3 made of a soft magnetic material and a plurality of permanent magnets 4 mounted on the outer circumference of the sleeve 3.

[0015] As shown in Figure 1, the sleeve 3 is cylindrical and made of a soft magnetic material, and comprises a cylindrical main body 3a, a plurality of annular grooves 3b provided in an annular shape along the circumferential direction on the outer circumference of the main body 3a and arranged at equal intervals along the axial direction, an annular guide portion 3c provided at one end of the main body 3a which is the left open end in Figure 1, and a screw portion 3d as a connecting mechanism provided on the outer circumference of the other end of the main body 3a which is the right open end in Figure 1.

[0016] In this embodiment, the axial width of each annular groove 3b is equal and longer than the width of the spacing between the convex portions 3f between the annular grooves 3b, 3b. The guide portion 3c is annular in shape, with an inner diameter smaller than that of the main body portion 3a and an outer diameter equal to that of the main body portion 3a, and is provided in conjunction with the left end, which is one end of the main body portion 3a. In addition, the guide portion 3c is provided with a ventilation hole 3e that penetrates the guide portion 3c in the axial direction, and an annular bush 9 is fitted to the inner circumference of the guide portion 3c.

[0017] A threaded portion 3d is provided on the outer circumference of the other end of the main body portion 3a of the sleeve 3, which is the rightmost end in Figure 1. As shown in Figure 2, the threaded portion 3d functions as a connecting mechanism that allows the assembly jig 20 used when assembling the cylindrical linear motor 1 to be attached.

[0018] Furthermore, a barrel connecting portion 3g is provided, which is a threaded portion formed in the area from the outer circumference of one end of the main body portion 3a of the sleeve 3, which is the leftmost end in Figure 1, to the outer circumference of the guide portion 3c.

[0019] Permanent magnets 4 are fitted into each annular groove 3b on the outer circumference of the sleeve 3. The permanent magnets 4 are formed by combining magnet pieces, each having a shape obtained by dividing a cylinder into multiple parts in the circumferential direction. In this embodiment, the magnet pieces are semi-cylindrical when viewed from the axial direction, and a cylindrical permanent magnet 4 is formed by combining two magnet pieces with their circumferential ends facing each other. Since the permanent magnets 4 are formed from magnet pieces divided in the circumferential direction in this way, they can be easily and smoothly fitted into the annular grooves 3b provided on the outer circumference of the sleeve 3.

[0020] Each permanent magnet 4 is magnetized in the axial direction, with one end in the axial direction being the N pole and the other end in the axial direction being the S pole. The triangles attached to each permanent magnet 4 in FIG. 1 indicate the magnetization direction. Each permanent magnet 4 is mounted in each annular groove 3b with the like poles of the permanent magnets 4 mounted in adjacent annular grooves 3b facing each other. That is, when each permanent magnet 4 is mounted in the annular groove 3b of the sleeve 3, the adjacent permanent magnets 4 and 4 face each other with the N poles and S poles facing each other across the convex portion 3f between the annular grooves 3b, 3b on the outer periphery of the main body portion 3a.

[0021] Therefore, in the tubular linear motor 1 of the present embodiment, one magnetic pole is formed from the axial center of the permanent magnet 4 to the axial center of the adjacent permanent magnet 4, and the convex portion 3f sandwiched between the N poles of the permanent magnets 4 and 4 with the N poles facing each other functions as one N pole, and the convex portion 3f sandwiched between the S poles of the permanent magnets 4 and 4 with the S poles facing each other functions as one S pole. In the field magnet 2 configured as described above, since the main body portion 3a of the sleeve 3 formed of a soft magnetic material is disposed on the inner peripheral side of the permanent magnet 4, the magnetic force lines going from the N pole to the S pole are biased and pass through the inner peripheral side of the sleeve 3 in large numbers, so that the magnetic field acting on the armature 6 accommodated in the inner periphery of the sleeve 3 can be increased. Even if the annular groove 3b is not provided on the outer periphery of the sleeve 3 and the permanent magnets 4 are simply laminated in the axial direction and attached to the outer periphery of the sleeve 3 to form the field magnet 2, it may be possible.

[0022] Note that the sleeve 3, like the cylindrical linear motor 1 of the present embodiment, is created by using a cylindrical body of a soft magnetic material as a base material and performing cutting on the outer periphery of the cylindrical body to form an annular groove 3b. Therefore, an annular groove 3b with a predetermined width can be installed at equal intervals with respect to the main body 3a with a small dimensional error. In the cylindrical linear motor 1 of the present embodiment, since the annular groove 3b is provided on the outer periphery of the sleeve 3 and the permanent magnet 4 is mounted in the annular groove 3b, even if a large number of permanent magnets 4 are arranged side by side in the axial direction on the outer periphery of the sleeve 3, the errors in the axial width of the permanent magnets 4 do not accumulate, the change in the pole pitch in the field magnet 2 in the axial direction can be suppressed, and the cogging thrust can be reduced. Also, in the present embodiment, although the permanent magnet 4 is mounted on the outer periphery of the sleeve 3, the permanent magnet 4 may be embedded inside the wall thickness of the cylindrical sleeve 3 to form the field magnet 2, and the cylindrical linear motor 1 may be configured as an IMP motor.

[0023] The field magnet 2 configured as described above is housed in a cylindrical barrel 10 formed of a non-magnetic material. The barrel 10 includes a cylindrical barrel main body 11 and a cap 12 that closes the right end of the barrel main body 11 in FIG. 1. The barrel main body 11 is cylindrical, and a sleeve connecting portion 11a formed of a screw portion that is screwed to a barrel connecting portion 3g provided on the outer periphery of one end of the sleeve 3 is provided on the inner periphery at the left end in FIG. 1, and a cap connecting portion 11b formed of a screw portion is provided on the outer periphery at the right end in FIG. 1.

[0024] A cap 12 having a bottomed cylindrical shape and provided with a bracket 12a used for attaching to an external device of the cylindrical linear motor 1 at the bottom is screwed to the cap connecting portion 11b of the barrel main body 11. Therefore, since the right end of the barrel main body 11 is closed by the cap 12, the barrel 10 has a bottomed cylindrical shape. Note that the barrel main body 11 and the cap 12 may be integrally formed to form the barrel 10.

[0025] In this manner, a sleeve 3 with a permanent magnet 4 attached is inserted into the barrel 10, which is closed at the right end by the cap 12, from the other end where a threaded portion 3d serving as a connecting mechanism is provided. The sleeve connecting portion 11a of the barrel body 11 is screwed into the barrel connecting portion 3g at one end of the sleeve 3, while the other end of the sleeve 3 is brought into contact with the cap 12. As a result, the field magnet 2 is held between the cap 12 that closes the end of the barrel body 11 and the threaded connection between the barrel connecting portion 3g of the sleeve 3 and the sleeve connecting portion 11a of the barrel body 11, and is fixed inside the barrel 10. A nut 13 that abuts the left end of the barrel body 11 in Figure 1 is screwed onto the barrel connecting portion 3g of the sleeve 3, and the tightening of the nut 13 prevents the barrel body 11 from loosening relative to the sleeve 3.

[0026] Sleeve 3 is inserted into the barrel 10 with its other end, which is the rightmost end in Figure 1, facing the cap 12 that forms the bottom of the barrel 10. No other parts are connected to the threaded portion 3d, which serves as a connecting mechanism, provided on the outer circumference of the other end, which is the rightmost end in Figure 1. In other words, Sleeve 3 is housed in the barrel 10 with its other end facing the cap 12, which forms the bottom of the barrel 10, without anything being connected to the threaded portion 3d, which serves as a connecting mechanism.

[0027] In the cylindrical linear motor 1 of this embodiment, the field magnet 2 is covered by a non-magnetic barrel 10, which protects the permanent magnet 4 mounted on the outer circumference of the sleeve 3 and prevents the permanent magnet 4 from scattering from the sleeve 3, and the barrel 10 suppresses the attraction of external iron-containing dust and other particles by the field magnet 2.

[0028] Next, the armature 6 is composed of a cylindrical core 14 and windings 15 attached to the core 14, and is inserted into the field 2 so as to be movable in the axial direction. In other words, in this embodiment, the armature 6 is located on the inner circumference side of the field 2 and can move relative to the field 2 in the axial direction.

[0029] In this embodiment, the core 14 comprises a cylindrical yoke 14a, a plurality of annular teeth 14b with a rectangular cross-section in the axial direction, provided on the outer circumference of the yoke 14a on the field side, along the circumferential direction and spaced apart in the axial direction, and a slot 14c formed in the gap between the teeth 14b, 14b, on which the winding 15 is mounted.

[0030] As described above, the yoke 14a is cylindrical, and its thickness is ensured so that its cross-sectional area is greater than or equal to the magnetic path cross-sectional area of ​​the teeth 14b. In this embodiment, as shown in Figure 1, seven teeth 14b are arranged at equal intervals in the axial direction on the outer circumference of the yoke 14a, and a slot 14c, which is an annular groove in which the winding 15 is mounted, is formed on the outer circumference side of the core 14 that is on the field 2 side. In this embodiment, the cross-sectional shape of the teeth 14b is rectangular, but it may also be trapezoidal, with the width of the base end being greater than the width of the tip end being the outer circumference, in order to ensure a large magnetic path cross-sectional area on the base end side.

[0031] In this embodiment, a total of six annular groove slots 14c are provided between adjacent teeth 14b, 14b in Figure 1. The slots 14c are provided along the circumferential direction of the core 14 and are arranged at equal pitches in the axial direction on the outer circumference of the core 14.

[0032] The windings 15 are then wound around and mounted in these slots 14c. The windings 15 are three-phase windings for the U, V, and W phases. The windings 15 for each phase are mounted in the six slots 14c in an arrangement appropriate to the magnetic pole arrangement of the field 2.

[0033] The armature 6 configured in this way is mounted on the outer circumference of the tip of the rod 5, which is made of a non-magnetic material and serves as the output shaft, and is movably inserted into the field 2 together with the rod 5.

[0034] Rod 5 protrudes outside the field 2 through a guide portion 3c provided at one end of the sleeve 3 in the field 2, which is the left end in Figure 1. Rod 5 slides against the inner circumference of a bush 9 mounted on the inner circumference of the guide portion 3c and is supported by the guide portion 3c of the sleeve 3, guiding the axial movement of rod 5 relative to the field 2. A threaded portion 5a is provided on the outer circumference of the tip of rod 5 as shown in Figure 2, and a bracket 19 is attached to the tip of rod 5, which is screw-connected to the threaded portion 5a as shown in Figure 1. The bracket 19 works in cooperation with the bracket 12a of the cap 12 to attach the cylindrical linear motor 1 to external equipment.

[0035] Furthermore, the armature 6 is mounted on the outer circumference of the base end of the rod 5 together with sliders 7 and 8. The sliders 7 and 8 are annular in shape and are mounted on the outer circumference of the rod 5, on both sides of the armature 6 in the axial direction, clamping the armature 6 and fixing it immovably in the axial direction relative to the rod 5.

[0036] Sliders 7 and 8 have an outer diameter slightly larger than the outer diameter of the armature 6, and both are equipped with wear rings 7a and 8a on their outer circumference that slide against the inner surface of the main body 3a of the sleeve 3. The sliding contact of sliders 7 and 8 against the inner surface of the main body 3a of the sleeve 3 creates a very small annular gap between the armature 6 and the main body 3a of the sleeve 3, and allows the armature 6 to move smoothly in the axial direction (left-right in Figure 1) relative to the sleeve 3 without axial wobble. In this way, since sliders 7 and 8 provided on both sides of the armature 6 slide against the inner surface of the main body 3a of the sleeve 3, which is made of a soft magnetic material, the magnetic gap between the field 2 and the armature 6 can be reduced, increasing the magnetic field that the field 2 acts on the armature 6, and ensuring the smooth axial movement of the armature 6.

[0037] In this embodiment, the cylindrical linear motor 1 has only one armature 6, but if it has multiple cores 14 and is mounted on the outer circumference of the rod 5, it is sufficient to provide at least three sliders in total: one between the cores 14, 14, one on the opposite side of one core 14, and one on the opposite side of the other core 14. However, if the width between the cores 14, 14 is wide, sliders may be placed on both sides of each of the cores 14, 14, for a total of four sliders.

[0038] Furthermore, since the tip of the rod 5 is supported by the guide portion 3c, and the sliders 7 and 8 are in sliding contact with the inner circumferential surface of the main body portion 3a of the sleeve 3, the rod 5, together with the armature 6, can move smoothly in the axial direction (left-right in Figure 1) within the sleeve 3 without any axial wobble.

[0039] Although not shown in the diagram, the rod 5 is cylindrical, and power can be supplied to the windings 15 from an external power source installed outside the cylindrical linear motor 1 via an external wire (not shown) passed through the rod 5. For example, by sensing the electrical angle of the windings 15 with respect to the field 2, and performing potential phase switching based on the electrical angle, and controlling the amount of current in each winding 15 by PWM control, the thrust and the direction of movement of the armature 6 in the cylindrical linear motor 1 can be controlled. Note that the above control method is just one example and is not limited to it. Furthermore, when an external force acts that causes relative axial displacement between the field 2 and the armature 6, the cylindrical linear motor 1 can be damped by generating a thrust that suppresses the relative displacement by energizing the windings 15 or by generating an induced electromotive force in the windings 15, thereby generating power from the external force and generating energy regeneration from the external force.

[0040] Next, the process of inserting the armature 6 into the sleeve 3 of the cylindrical linear motor 1 configured as described above will be explained. First, the barrel connecting portion 3g of the sleeve 3 is screw-connected to a fixing jig 21 which is fixed to a workbench (not shown) and attaches the sleeve 3 to the workbench, thereby fixing the sleeve 3 to the fixing jig 21. The fixing jig 21 comprises a base portion 21a attached to a workbench (not shown) and an annular nut portion 21b provided at the upper end of the base portion 21a. When the barrel connecting portion 3g is screw-connected to the nut portion 21b, it holds the sleeve 3 and can fix the sleeve 3 to the workbench.

[0041] Furthermore, as mentioned above, a threaded portion 3d is provided on the outer circumference of the other end of the sleeve 3, which constitutes the field 2, and the cylindrical assembly jig 20 is connected to the other end of the sleeve 3 using the threaded portion 3d.

[0042] The assembly jig 20 is cylindrical, with an enlarged inner diameter at its left end in Figure 2. This enlarged portion is equipped with a threaded portion 20a that can be screwed onto the outer circumference of the threaded portion 3d at the other end of the sleeve 3. The inner diameter of the threaded portion 20a on the right side in Figure 2 matches the inner diameter of the main body portion 3a of the sleeve 3. Furthermore, the length L1 of the guide surface 20b, which is the inner circumferential surface of the assembly jig 20 in the portion whose inner diameter matches that of the sleeve 3, is at least longer than the total length L2 obtained by adding the axial length of the slider 7 and the axial length of the armature 6.

[0043] Since the length L1 of the guide surface of the assembly jig 20 is longer than the total length L2, the entire slider 7 and armature 6, and at least a part of slider 8, can be accommodated within the range of the guide surface, and sliders 7, 8 and armature 6 can be supported by the guide surface 20b. Preferably, the total length L1 of the guide surface 20b is longer than the axial length L3 from the left end of slider 7 on the left in Figure 2, across armature 6, to the right end of slider 8 on the right in Figure 2, so that the entire sliders 7, 8 and armature 6 can be accommodated within the guide surface 20b. Furthermore, if the length L1 of the guide surface 20b is longer than the total length L2, the inner diameter of the right end of the assembly jig 20 beyond the guide surface 20b may be larger than the inner diameter of sleeve 3.

[0044] The assembly jig 20, configured in this way, is connected to the other end of the sleeve 3 by screwing the threaded portion 20a formed on the inner circumference of the left end to the threaded portion 3d, which serves as a connecting mechanism. When the assembly jig 20 is connected to the other end of the sleeve 3, the guide surface 20b of the assembly jig 20 becomes flush with the inner circumferential surface of the main body portion 3a of the sleeve 3, and a circumferential surface is formed between the guide surface 20b and the inner circumferential surface of the main body portion 3a in which the inner diameter does not change. The assembly jig 20 may be made of a magnetic material or a non-magnetic material.

[0045] The rod 5, with sliders 7, 8 and armature 6 assembled on its outer circumference, is inserted into the sleeve 3, which is fixed to the workbench and has an assembly jig 20 attached to the other end, starting from the right end of the assembly jig 20 in Figure 2, with the rod 5 leading. The sliders 7, 8 and armature 6 are inserted into the assembly jig 20. The armature 6 does not generate a magnetic force when the winding 15 is not energized, so inserting the armature 6 into the assembly jig 20 is easy. The insertion of the rod 5, with sliders 7, 8 and armature 6 assembled on its outer circumference, into the sleeve 3 is performed without attaching the bracket 19 to the tip of the rod 5.

[0046] When the entire slider 7 and armature 6, and at least a portion of the slider 8 are housed within the guide surface 20b of the assembly jig 20, the rod 5, armature 6, and sliders 7 and 8 are supported by the guide surface 20b, which is flush with the inner circumferential surface of the main body portion 3a of the sleeve 3. As a result, the axes of the armature 6 and rod 5 align with the axis of the sleeve 3 when viewed in the axial direction. In other words, the rod 5, armature 6, and sliders 7 and 8 are aligned with the sleeve 3 by the assembly jig 20. Then, when the rod 5 is pushed to the left in Figure 2 to move the armature 6 and sliders 7 and 8 into the main body portion 3a of the sleeve 3, the guide surface 20b of the assembly jig 20 and the inner circumferential surface of the main body portion 3a of the sleeve 3 are flush. Therefore, the armature 6 and sliders 7 and 8 can move smoothly into the sleeve 3 without axial wobble while being aligned by the assembly jig 20 and the sleeve 3. Furthermore, since the rod 5 is also centered, just like the armature 6 and sliders 7 and 8, the rod 5 can also smoothly enter the guide portion 3c and bush 9 in the sleeve 3. In order to facilitate the insertion of the armature 6 and sliders 7 and 8 into the assembly jig 20, it is advisable to chamfer the inner periphery of the right end of Figure 2, which is the end of the assembly jig 20 opposite the sleeve, to provide a lead-in chamfer.

[0047] Even when the entire armature 6 and sliders 7 and 8 are inserted into the sleeve 3, the sliders 7 and 8 do not slide against the inner circumferential surface of the main body 3a, preventing the armature 6 from being radially eccentric with respect to the main body 3a of the sleeve 3, and allowing the rod 5, armature 6, and sliders 7 and 8 to move smoothly in the axial direction.

[0048] By connecting the assembly jig 20 to the screw portion 3d of the sleeve 3, which serves as a connecting mechanism, and using the assembly jig 20 as a guide for inserting the rod 5, armature 6, and sliders 7 and 8 into the sleeve 3, the attractive force between the permanent magnet 4 and the armature 6 is balanced in the circumferential direction, making it easy to assemble the cylindrical linear motor 1 and reducing the workload on the operator.

[0049] As described above, the assembly jig 20 is connected to the sleeve 3 before inserting the armature 6 and sliders 7 and 8, which are mounted on the outer circumference of the rod 5, into the assembly jig 20. However, before connecting the assembly jig 20 to the sleeve 3, the sliders 7 and 8 and the armature 6, which are assembled on the outer circumference of the rod 5, may be inserted into the assembly jig 20 in advance, and then the assembly jig 20 may be connected to the sleeve 3 via the connecting mechanism. Also, in this embodiment, the sleeve 3 is fixed to the workbench by screwing it to a fixing jig 21 attached to the workbench using the barrel connecting portion 3g formed on the outer circumference of one end of the sleeve 3. However, when inserting the rod 5, armature 6, and sliders 7 and 8 into the sleeve 3 using the assembly jig 20, if it is not necessary to fix the sleeve 3 to the workbench, the fixing jig 21 may not be used.

[0050] Furthermore, since the threaded portion 3d of the connecting mechanism is provided on the outer circumference of the other end of the main body portion 3a of the sleeve 3, the slider 8 can stroke to the other end of the main body portion 3a of the sleeve 3 without interfering with the threaded portion 3d, making it easier to secure the stroke length of the cylindrical linear motor 1. For this reason, it is preferable to provide the connecting mechanism on the outer circumference of the other end of the sleeve 3, but if there is no problem with the stroke length, the connecting mechanism may be provided on the inner circumference of the other end of the sleeve 3. Specifically, the inner diameter of the inner circumference of the other end of the main body portion 3a may be enlarged and a threaded portion may be provided on the inner circumference of the other end, and a threaded portion may be provided on the outer circumference of the end of the assembly jig 20 that is screw-connected to the threaded portion as the connecting mechanism on the sleeve 3 side.

[0051] Furthermore, although the connecting mechanism is described as a screw portion 3d as mentioned above, any mechanism that enables a secure and detachable connection with minimal play between the assembly jig 20 and the sleeve 3 is acceptable. Therefore, it may also be a mechanism that enables a connection by fitting rather than a screw portion, or any other connecting mechanism may be used.

[0052] As described above, the cylindrical linear motor 1 of this embodiment comprises a field 2 having a cylindrical sleeve 3 made of a soft magnetic material and a plurality of permanent magnets 4 mounted on the outer circumference of the sleeve 3, a rod 5 inserted into the inside of the sleeve 3 so as to be movable in the axial direction and protruding to the outside of the sleeve 3 from one end of the sleeve 3, an armature 6 mounted on the outer circumference of the rod 5 and inserted into the sleeve 3, and a plurality of sliders 7, 8 mounted on the outer circumference of the rod 5 on both sides in the axial direction of the armature 6 and slidingly contacting the inner circumference of the sleeve 3, and the sleeve 3 is provided with a screw portion (connecting mechanism) 3d at the other end.

[0053] With the cylindrical linear motor 1 configured in this way, the sleeve 3 is equipped with a screw portion (connecting mechanism) 3d at the other end, and the assembly jig 20 used in the process of inserting the armature 6 and sliders 7 and 8 into the sleeve 3 can be connected to the sleeve 3 using the screw portion (connecting mechanism) 3d. Therefore, it is less susceptible to the effects of attraction by the field 2, making it easier to insert the rod 5, armature 6, and sliders 7 and 8 into the sleeve 3 and reducing the workload on the operator. Thus, the cylindrical linear motor 1 of this embodiment can be easily assembled.

[0054] Furthermore, the cylindrical linear motor 1 of this embodiment includes a barrel 10 that is bottomed and made of a non-magnetic material to house the field magnet 2, and the sleeve 3 is housed in the barrel 10 with its other end facing the bottom of the barrel 10, without anything being connected to the screw portion (connecting mechanism) 3d. With the cylindrical linear motor 1 configured in this way, the sleeve 3 is housed inside the barrel 10 with the other end of the sleeve 3 facing the bottom of the barrel 10, rather than the one end of the sleeve 3 from which the rod 5 protrudes, so that the screw portion (connecting mechanism) 3d can be protected by the barrel 10.Therefore, with the cylindrical linear motor 1 of this embodiment, when the armature 6 that has been removed from inside the sleeve 3 during maintenance is reinserted into the sleeve 3, the assembly jig 20 which requires high precision to be attached to the sleeve 3 can be properly connected, and the workability during maintenance is not impaired.

[0055] Although preferred embodiments of the present invention have been described in detail above, modifications, alterations, and changes are permitted as long as they do not deviate from the scope of the claims. [Explanation of Symbols]

[0056] 1. Cylindrical linear motor, 2. Field, 3. Sleeve, 3d. Screw section (connecting mechanism), 4. Permanent magnet, 5. Rod, 6. Armature, 7,8. Slider, 10. Barrel

Claims

1. A field magnet comprising a cylindrical sleeve formed of a soft magnetic material and a plurality of permanent magnets mounted in the sleeve, A rod is inserted into the inside of the sleeve so as to be movable in the axial direction and protrudes from one end of the sleeve to the outside of the sleeve, An armature is mounted on the outer circumference of the rod and inserted into the sleeve, The rod comprises a plurality of sliders mounted on both sides of the armature in the axial direction on the outer circumference of the rod, which slide against the inner circumference of the sleeve. The sleeve has a connecting mechanism at the other end. A cylindrical linear motor characterized by the following features.

2. It comprises a bottomed cylindrical barrel made of a non-magnetic material that houses the field, The sleeve is housed in the barrel with its other end facing the bottom of the barrel, without being connected to the coupling mechanism. The cylindrical linear motor according to feature 1.

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