Linear motor and method for manufacturing the same

Abstract

To provide a linear motor that causes no reduction in thrust while protecting a permanent magnet, and a method for manufacturing the same.SOLUTION: A linear motor 1 includes a field magnet F and an armature E capable of reciprocating in a longitudinal direction of the field magnet F. The field magnet F includes: a guide member 2 having a sliding surface 23 on which the armature E slides facing the armature E and formed by alternately stacking a plurality of magnetic path forming sections 21 of soft magnetic material and nonmagnetic path forming sections 22 of nonmagnetic material along the longitudinal direction; a plurality of permanent magnets 3a, 3b disposed on a non-armature side of the nonmagnetic path forming section 22 of the guide member 2; and a plurality of soft magnetic yokes 4 or second permanent magnets disposed between the adjacent permanent magnets 3a and 3b on the non-armature side of the magnetic path forming section 21 of the guide member 2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a linear motor and a method for manufacturing a linear motor. [Background technology]

[0002] A conventional linear motor is configured, for example, with a cylindrical field magnet formed by arranging multiple permanent magnets so that north and south poles appear alternately, and an armature that is inserted into the inner circumference of the field magnet and can move in the longitudinal direction of the field magnet.

[0003] In conventional linear motors, in order to improve the ease of assembly of permanent magnets, a cover made of a non-magnetic or soft magnetic material is provided, which has a cylindrical magnet mounting portion that fits into the inner circumference of the permanent magnet facing the armature, and a protrusion that protrudes radially from the outer circumference of the magnet mounting portion.The motor is manufactured by attaching multiple permanent magnets to the cover to assemble it, and then stacking the assembled covers (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-210048 A Summary of the Invention [Problem to be solved by the invention]

[0005] A linear motor configured in this manner is easier to assemble, but if the cover is made of a non-magnetic material, the magnet mounting portion of the cover is located between the permanent magnet and the armature, which means that the magnetic resistance of the magnet mounting portion is large, making it difficult to apply a large magnetic field from the permanent magnet to the armature, resulting in a decrease in thrust.

[0006] On the other hand, if the cover is made of a soft magnetic material, the amount of short-circuiting magnetic flux that passes through the magnet mounting part located on the armature side of the permanent magnet and short-circuits the north and south poles of the permanent magnet increases, making it difficult to generate a strong magnetic field from the permanent magnet to the armature, resulting in a decrease in thrust. Thus, while providing a cover on the armature side of the permanent magnet can protect the permanent magnet, it also has the problem of reducing the thrust of the linear motor.

[0007] Furthermore, in conventional linear motors, because a cover is placed between the permanent magnet and the armature, the armature cannot be placed very close to the field, making it difficult to apply a large magnetic field to the armature.

[0008] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a linear motor that protects the permanent magnets while preventing a decrease in thrust, and a method for manufacturing the linear motor. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the linear motor of the present invention comprises a field magnet and an armature capable of reciprocating in the longitudinal direction of the field magnet, the field magnet comprising a guide member having a sliding surface opposite the armature along which the armature slides and formed by alternately stacking multiple magnetic path forming portions of soft magnetic material and non-magnetic path forming portions of non-magnetic material along the longitudinal direction, a plurality of first permanent magnets arranged on the anti-armature side of the non-magnetic path forming portions of the guide member and magnetized along the longitudinal direction of the field magnet, and a plurality of yokes made of soft magnetic material arranged between adjacent first permanent magnets on the anti-armature side of the magnetic path forming portions of the guide member, or a second permanent magnet arranged between adjacent first permanent magnets on the anti-armature side of the magnetic path forming portions of the guide member and magnetized along a direction facing the armature.

[0010] In a linear motor configured in this manner, the first permanent magnet is arranged on the anti-armature side of the non-magnetic path forming portion of the guide member, and is also arranged between the yokes or between the second permanent magnets arranged on the anti-armature side of the magnetic path forming portion of the guide member. Therefore, while the permanent magnets are protected by the guide member, the short-circuit magnetic flux that passes between the first permanent magnet and the armature and short-circuits between the magnetic poles is reduced, and the magnetic flux of the first permanent magnet can pass to the armature side via the yoke or second permanent magnet and the magnetic path forming portion. In addition, by providing the guide member with a sliding surface along which the armature slides, the armature can be arranged in close proximity to the field magnet, and a large magnetic field can be applied to the armature to improve thrust.

[0011] Also, the length of the permanent magnet in the linear motor along the longitudinal direction of the field magnet may be longer than the length of the non-magnetic-path-forming portion along the longitudinal direction of the field magnet, and the first permanent magnet may be in contact with the magnetic-path-forming portions on both sides of the non-magnetic-path-forming portion in the guide member. With a linear motor configured in this manner, the armature side of the first permanent magnet reliably faces the non-magnetic-path-forming portion and both ends of the armature side face the magnetic-path-forming portions, and the yoke or second permanent magnet is also reliably positioned on the anti-armature side of the magnetic-path-forming portions, so that a large magnetic field can be applied to the armature with high reliability, improving thrust.

[0012] Also, the magnetic path forming portion and the non-magnetic path forming portion of the guide member in the linear motor may be integrated in a state where they are alternately stacked, and each yoke may be integrated with a corresponding magnetic path forming portion in the guide member. With a linear motor configured in this manner, the first permanent magnet can be appropriately positioned on the outer periphery of the non-magnetic path forming portion, and even if there is variation in the length dimension of the first permanent magnet, the first permanent magnet can be positioned at an appropriate position relative to the guide member without error being stacked. Also, the guide member and the yoke are integrated to form a single component, and there is no misalignment between the magnetic path forming portion and the non-magnetic path forming portion in the guide member, making it easier to form a sliding surface and increasing the bending rigidity to suppress the application of bending moment to the first permanent magnet.

[0013] In addition, according to a manufacturing method for a linear motor of the present invention, there is provided a manufacturing method for a linear motor that is cylindrical and has a sliding surface on its inner circumference in which soft magnetic material and non-magnetic material are alternately stacked and integrated along the longitudinal direction, and is equipped with a field magnet in which a first permanent magnet is attached to its outer circumference, the manufacturing method including a joining process for manufacturing a cylindrical body by joining multiple alternately stacked annular base materials formed of soft magnetic material and multiple annular base materials formed of non-magnetic material, a polishing process for polishing the inner surface of the cylindrical body to form a sliding surface, and a groove forming process for forming multiple annular grooves on the outer circumference of the cylindrical body in which the permanent magnets are attached.

[0014] According to the manufacturing method of the linear motor configured in this manner, the guide member and the yoke can be molded integrally, and the annular groove for accommodating the first permanent magnet can be formed in advance in the sleeve at an equal pitch. Therefore, even if there is variation in the length dimension of the first permanent magnet, errors can be accumulated and the first permanent magnet can be appropriately positioned on the outer periphery of the non-magnetic material, and a linear motor can be manufactured that has a sliding surface and can be positioned in close proximity to the armature, reducing short-circuit magnetic flux, and capable of applying a large magnetic field to the armature. Effect of the Invention

[0015] According to the linear motor and the method for manufacturing the linear motor of the present invention, it is possible to protect the permanent magnets without causing a decrease in thrust. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a vertical cross-sectional view of a linear motor according to an embodiment. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of a portion of the field and armature of the linear motor according to the embodiment. [Diagram 3] Fig. 3(a) is a diagram illustrating a joining process for joining soft magnetic bodies and non-magnetic bodies that are alternately laminated, Fig. 3(b) is a diagram illustrating a polishing process for polishing the inner peripheral surface of a cylindrical body, and Fig. 3(c) is a diagram illustrating a groove forming process for forming an annular groove on the outer periphery of the cylindrical body. [Figure 4]FIG. 4 is an enlarged cross-sectional view of a part of a field magnet of a linear motor according to a first modified example of the embodiment. [Diagram 5] FIG. 5 is an enlarged cross-sectional view of a part of a field magnet of a linear motor according to a second modified example of the embodiment. [Figure 6] FIG. 6 is an enlarged cross-sectional view of a part of a field magnet of a linear motor according to a third modified example of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present invention will be described below based on the embodiment shown in the drawings. As shown in Fig. 1, a linear motor 1 in one embodiment is a cylindrical linear motor that includes a cylindrical field magnet F and an armature E that is capable of reciprocating in the axial direction, which is the longitudinal direction of the field magnet F, on the inner periphery of the field magnet F.

[0018] Hereinafter, each part of the linear motor 1 will be described in detail. In this embodiment, the field magnet F is cylindrical, has a sliding surface 23 facing the armature E on which the armature E slides, and includes a guide member 2 formed by alternately stacking magnetic path forming parts 21 made of soft magnetic material and non-magnetic path forming parts 22 made of non-magnetic material along the longitudinal direction, a plurality of first permanent magnets 3a, 3b arranged on the anti-armature side of the non-magnetic path forming parts 22 of the guide member 2 and magnetized along the longitudinal direction of the field magnet F, and a plurality of yokes 4 made of soft magnetic material arranged on the anti-armature side of the magnetic path forming parts 21 of the guide member 2 and between adjacent first permanent magnets 3a, 3b.

[0019] In the linear motor 1 of this embodiment, as shown in Figs. 1 and 2, the guide member 2 is formed into a cylindrical shape by joining a plurality of annular magnetic path forming parts 21 made of soft magnetic material and a plurality of annular non-magnetic ...

[0020] Further, an annular yoke 4 is provided on the outer periphery of the guide member 2 on the anti-armature side thereof, facing the magnetic path forming portion 21 and integral with the magnetic path forming portion 21, and the guide member 2 and the yoke 4 form a sleeve S. The yoke 4 is made of a soft magnetic material, arranged on the outer periphery of the magnetic path forming portion 21 and integral with the magnetic path forming portion 21, and protrudes radially from the outer periphery of the magnetic path forming portion 21 of the guide member 2 to form an annular groove G in which the first permanent magnets 3a, 3b are respectively attached on the outer periphery of the non-magnetic path forming portion 22 of the guide member 2 on the anti-armature side. In this way, the sleeve S has the annular groove G between the yokes 4, 4 made of a soft magnetic material on the outer periphery of the non-magnetic path forming portion 22 in the axial direction.

[0021] In this way, the guide member 2 and the yoke 4 integrated with the magnetic path forming portion 21 of the guide member 2 are manufactured as follows. As shown in FIG. 3(a), a plurality of annular base materials A made of a soft magnetic material and a plurality of annular base materials B made of a non-magnetic material are alternately stacked and bonded together, and then the annular base materials A and B are axially pressurized at a temperature below the melting point of the annular base materials A and B to an extent that does not cause plastic deformation, and diffusion bonding is performed to cause atomic diffusion between the bonding surfaces of the annular base materials A and B, thereby bonding the annular base materials A and B together (bonding process). In this way, when the annular base materials A and B are diffusion bonded together, a cylindrical body T is obtained by bonding the plurality of annular base materials A and B in a stacked state without misalignment or distortion. The annular base material A may be, for example, SUS430, which is a stainless steel exhibiting ferromagnetic properties, and the annular base material B may be, for example, SUS304, which is a stainless steel exhibiting no magnetic properties, but they may be formed of other soft magnetic materials and non-magnetic materials.

[0022] In order to use the inner circumferential surface of the cylindrical body T thus obtained as a sliding surface against which the armature E slides, as shown in FIG. 3(b), the cylindrical body T is rotated and the inner circumferential surface of the cylindrical body T is ground with a grindstone 100 to form the inner circumferential surface of the cylindrical body T into a smooth, flush cylindrical sliding surface 23 (grinding process).

[0023] Furthermore, as shown in FIG. 3(c), the outer periphery of the annular base material B of the cylindrical body T, which is made of a non-magnetic material, is cut with a tool 101 to form a plurality of annular grooves G arranged along the axial direction on the outer periphery of the cylindrical body T (groove forming process). The outer periphery of the cylindrical body T may be ground to form the annular grooves G. When the groove forming process is completed, on the outer periphery side of the cylindrical body T, the outer diameter of the annular base material A becomes larger than the outer diameter of the processed annular base material B and protrudes to the outer periphery, and the annular grooves G are formed by gaps formed between the outer peripheries of the annular base materials A adjacent to each other in the axial direction with the annular base material B sandwiched therebetween. In this way, the annular groove G faces the annular base material A, both axial ends of which are made of a soft magnetic material, when the cylindrical body T is viewed in the axial direction.

[0024] When the above-mentioned processing is completed, the guide member 2 is formed in which the magnetic path forming portions 21 made of soft magnetic material and the non-magnetic path forming portions 22 made of non-magnetic material are alternately laminated and integrally joined in a cylindrical portion inside a virtual circle passing through the bottom surface of the annular groove G of the cylinder T when viewed from the axial direction of the cylinder T, and the yoke 4 is formed in a portion of the cylinder T that intermittently protrudes to the outer periphery with the annular groove G made of soft magnetic material sandwiched therebetween. In addition, a polishing process forms a flush sliding surface 23 without irregularities on the inner periphery of the guide member 2. When the above-mentioned processing is completed, a cylindrical sleeve S including the guide member 2 and a plurality of yokes 4 integrated with the magnetic path forming portions 21 of the guide member 2 can be manufactured.

[0025] As described above, in manufacturing the sleeve S having the guide member 2 and the yoke 4 integrally therewith, the polishing process is carried out prior to the groove forming process after the cylindrical body T is obtained, but it is also possible to carry out the polishing process of the inner circumference of the cylindrical body T after the groove forming process.

[0026] In addition, in this embodiment, the annular base materials A and B can be joined in a stacked state while suppressing misalignment and distortion between them by performing diffusion bonding, and the dimensional change in the axial direction of the annular base materials A and B can be suppressed during bonding, which is advantageous in that even if the annular grooves G in which the first permanent magnets 3a and 3b are attached are formed at equal pitches in the axial direction, they can be formed with little misalignment on the outer periphery of the annular base material B, which is a non-magnetic material. In addition to diffusion bonding, bonding by adhesion or pressure welding may be used to bond the annular base materials A and B, and in the case of bonding by adhesion, the material of the annular base materials A and B is not limited to metal. Furthermore, in the above description, the annular base materials A and B are alternately stacked and bonded to manufacture the cylindrical body T, but the cylindrical body T may be obtained by stacking and bonding a plate-shaped base material formed of a soft magnetic material and a plate-shaped base material formed of a non-magnetic material, and then performing hole drilling and cutting on the outside of the workpiece obtained.

[0027] As described above, since the yoke 4 is provided integrally with the guide member 2 by processing the outer periphery of the cylindrical body T to form the annular groove G, the annular groove G for mounting the first permanent magnets 3a, 3b can be provided at a desired position on the guide member 2, and even if there is variation in the axial length of the first permanent magnets 3a, 3b, the first permanent magnets 3a, 3b can be mounted at an appropriate position on the guide member 2. Furthermore, since the magnetic path forming portion 21 and the non-magnetic path forming portion 22 in the guide member 2 are integrated, and in addition, the magnetic path forming portion 21 and the yoke 4 are integrated, bending rigidity can be increased and bending moment applied to the first permanent magnets 3a, 3b can be suppressed.

[0028] Next, the first permanent magnets 3a, 3b are magnetized along the longitudinal direction of the field magnet F, and are permanent magnets whose magnetization direction is the axial direction, with one axial end being an N pole and the other axial end being an S pole, and are installed alternately in the axial direction within the annular groove G in the sleeve S.

[0029] Each of the first permanent magnets 3a and 3b is formed by combining magnet pieces having a shape obtained by dividing a cylinder into a plurality of pieces in the circumferential direction. In this embodiment, the magnet pieces are semi-cylindrical when viewed from the axial direction, and the cylindrical first permanent magnets 3a and 3b are formed by combining two magnet pieces with their circumferential ends facing each other. Since the first permanent magnets 3a and 3b are formed of magnet pieces divided in the circumferential direction in this manner, they can be easily and naturally mounted in the annular groove G formed between the yokes 4, 4 on the outer periphery of the sleeve S in which the guide member 2 and the yoke 4 are integrated. In addition, the axial width of the first permanent magnets 3a and 3b is approximately the same as the axial width of the annular groove G, but is slightly smaller, so that the first permanent magnets 3a and 3b can be fitted into the annular groove G.

[0030] Although not shown in detail, when the annular groove G is formed by cutting the outer periphery of the cylinder T, it is difficult to make the corners at both axial ends of the bottom of the annular groove G into pin angles. Therefore, by chamfering both ends of the inner circumference of the first permanent magnets 3a, 3b so that the inner periphery of the first permanent magnets 3a, 3b do not interfere with the corners at both axial ends of the bottom of the annular groove G, the first permanent magnets 3a, 3b can be prevented from lifting up from the outer periphery of the guide member 2, which forms the bottom of the annular groove G, and the axial side surface of the yoke 4 and the axial end faces of the first permanent magnets 3a, 3b can be in surface contact with each other, which prevents stress from concentrating on parts of the first permanent magnets 3a, 3b due to the axial load received when the armature E is driven.

[0031] Returning to the above, the first permanent magnets 3a, 3b are alternately mounted in the annular groove G of the sleeve S such that the N poles of adjacent first permanent magnets 3a and 3b face each other and the S poles of adjacent first permanent magnets 3a, 3b face each other with the yoke 4 in between. Thus, when the first permanent magnets 3a, 3b are mounted in the annular groove G, the yoke 4 is disposed between the first permanent magnets 3a, 3b in the axial direction of the sleeve S, and since the annular groove G is formed on the outer periphery of the non-magnetic path forming portion 22 of the guide member 2, the first permanent magnets 3a, 3b are disposed on the outer periphery side of the non-magnetic path forming portion 22 of the guide member 2. In addition, the yoke 4 is integral with the outer periphery of the magnetic path forming portion 21 of the guide member 2.

[0032] 2, in the linear motor 1 of this embodiment, the magnetic field lines from the N poles of the first permanent magnets 3a, 3b pass through the yoke 4 and the magnetic path forming portion 21 made of the soft magnetic material of the guide member 2, pass through the armature E inserted on the inner circumferential side of the sleeve S, and further pass through the adjacent magnetic path forming portion 21 and the yoke 4 across the non-magnetic path forming portion 22 to reach the S poles of the first permanent magnets 3a, 3b. Thus, one magnetic pole is formed from the center of the axial direction of the first permanent magnet 3a to the center of the axial direction of the first permanent magnet 3b adjacent to the first permanent magnet 3a, and the N poles of the first permanent magnets 3a, 3b, whose N poles face each other, and the magnetic path forming portion 21 and the yoke 4 sandwiched between the N poles function as one N pole, and the S poles of the first permanent magnets 3a, 3b, whose S poles face each other, and the magnetic path forming portion 21 and the yoke 4 sandwiched between the S poles function as one S pole.

[0033] In addition, a non-magnetic path forming portion 22 made of a non-magnetic material that has high magnetic resistance and through which magnetic flux does not easily pass is disposed on the inner circumference side, which is the armature side, of the first permanent magnets 3a, 3b. As a result, the amount of short-circuit magnetic flux passing through the non-magnetic path forming portion 22 as shown by the dashed line in FIG. 2 is reduced, and more magnetic flux passes through the armature E on the inner circumference side of the guide member 2, thereby making it possible to increase the magnetic field acting on the armature E.

[0034] The field magnet F configured in this manner is housed in a cylindrical barrel 5 made of a non-magnetic material. The left ends of the barrel 5 and the field magnet F in FIG. 1 are closed by a cap 6, and the right ends of the barrel 5 and the field magnet F in FIG. 1 are closed by an annular head cap 7. In the linear motor 1 of this embodiment, the field magnet F is covered by the barrel 5 made of a non-magnetic material, which protects the first permanent magnets 3a and 3b attached to the outer periphery of the sleeve S and prevents the first permanent magnets 3a and 3b from scattering from the sleeve S, and also prevents external dust containing iron from being attracted by the field magnet F. Furthermore, the field magnet F is housed within the barrel 5, the outer periphery of the guide member 2 is restrained by the barrel 5 via the first permanent magnets 3a, 3b and the yoke 4 to restrict radial displacement between the magnetic path forming portion 21 and the non-magnetic path forming portion 22, and the guide member 2 is sandwiched between the cap 6 and the head cap 7 to fix the magnetic path forming portion 21 and the non-magnetic path forming portion 22 in a stacked state, so that a flush sliding surface 23 without irregularities can be formed on the inner periphery of the magnetic path forming portion 21 and the non-magnetic path forming portion 22. Therefore, as long as the armature side surface of the guide member 2 can be made into the sliding surface 23, the magnetic path forming portion 21 and the non-magnetic path forming portion 22 do not have to be alternately stacked and integrated without being joined. However, when the magnetic path forming portion 21 and the non-magnetic path forming portion 22 are joined and integrated in a stacked state, no misalignment occurs between the magnetic path forming portion 21 and the non-magnetic path forming portion 22, making it easier to form the sliding surface 23 on the guide member 2 and increasing the bending rigidity of the guide member 2 to suppress bending stress acting on the first permanent magnets 3a, 3b.

[0035] Next, the armature E is configured to include a cylindrical core 8, a winding 9 attached to the core 8, and a guide 10 that comes into sliding contact with a sliding surface 23, which is the inner peripheral surface of the guide member 2 of the sleeve S, and is inserted into the field magnet F so as to be movable in the axial direction. That is, in this embodiment, the armature E is disposed on the inner peripheral side of the field magnet F, and can move relative to the field magnet F in the axial direction.

[0036] In this embodiment, the core 8 is configured to include a cylindrical yoke 8a, a plurality of teeth 8b having a rectangular axial cross section that are annular and arranged circumferentially and axially spaced apart from one another on the outer periphery of the yoke 8a, which is the field side of the core 8, and slots 8c formed by the gaps between the teeth 8b, 8b, into which the windings 9 are attached.

[0037] As described above, the yoke 8a is cylindrical, and the thickness is ensured so that the cross-sectional area is equal to or larger than the magnetic path cross-sectional area of ​​the teeth 8b. In this embodiment, as shown in Fig. 1 and Fig. 2, seven teeth 8b are arranged at equal intervals in the axial direction on the outer periphery of the yoke 8a, and a slot 8c, which is an annular groove in which the winding 9 is fitted, is formed between the teeth 8b, 8b on the outer periphery side that is the field magnet F side of the core 8. In this embodiment, the cross-sectional shape of the teeth 8b is rectangular, but it may be trapezoidal in which the width on the inner periphery, the base end side, is larger than the width on the outer periphery, the tip side, so that a large magnetic path cross-sectional area on the base end side can be ensured.

[0038] In this embodiment, a total of six slots 8c each made of annular grooves are provided between adjacent teeth 8b, 8b in Fig. 1. The slots 8c are provided along the circumferential direction of the core 8 and are arranged at equal pitches in the axial direction on the outer periphery of the core 8.

[0039] The windings 9 are wound around the slots 8c. The windings 9 are three-phase windings having U, V, and W phases. The windings 9 for each phase are mounted in the six slots 8c in an appropriate arrangement according to the magnetic pole arrangement of the field magnet F.

[0040] The armature E thus constructed is attached to the outer periphery of the tip of a rod 11 which is an output shaft and is made of a non-magnetic material, and is inserted into the field magnet F together with the rod 11 so as to be freely movable.

[0041] The rod 11 protrudes outside the linear motor 1 through a head cap 7 attached to the right end of the field magnet F in Fig. 1. Annular guides 10, 10 having annular wear rings 10a on their outer periphery that come into sliding contact with the sliding surface 23 of the guide member 2 in the field magnet F are attached to the left and right sides of the core 8 of the rod 11 in Fig. 1.

[0042] In this manner, the core 8 is sandwiched by the guides 10, 10 from both sides in the axial direction and fixed to the rod 11. The armature E is provided with guides 10, 10 that are in sliding contact with the sliding surface 23, which is the inner peripheral surface of the guide member 2, and can slide within the guide member 2 in the axial direction, which is the longitudinal direction of the field magnet F, and can therefore move in the axial direction without axial wobble relative to the field magnet F and without interfering with the field magnet F. In this manner, the armature E's axial movement relative to the field magnet F is guided by the guide member 2 that faces the armature E in the field magnet F.

[0043] Furthermore, the guide member 2 has a magnetic path forming portion 21 made of soft magnetic material facing the armature E and through which the magnetic flux of the first permanent magnets 3a, 3b passes, which not only protects the first permanent magnets 3a, 3b but also reduces the magnetic gap between the armature E and the field magnet F, thereby increasing the magnetic field that acts on the armature E and acting in cooperation with the guides 10, 10 to guide the axial movement of the core 8. The outer diameter of the core 8 is smaller than the inner diameter of the guide member 2 and does not interfere with the guide member 2, allowing the linear motor 1 to smoothly extend and retract.

[0044] Although not shown, rod 11 is cylindrical, and power can be supplied to windings 8 from an external power source installed outside linear motor 1 through an electric wire (not shown) that passes through rod 11.

[0045] For example, by sensing the electrical angle of the windings 9 with respect to the field F, switching the energized phase based on the electrical angle, and controlling the amount of current in each winding 9 by PWM control, it is possible to control the thrust and the direction of movement of the armature E in the linear motor 1. Note that the above-mentioned control method is an example and is not limited to this. Furthermore, when an external force acts that causes a relative displacement between the armature E and the field F in the axial direction, a thrust that suppresses the relative displacement can be generated by energizing the windings 9 or by induced electromotive force generated in the windings 9, allowing the linear motor 1 to damp the vibration and movement of the equipment caused by the external force, and energy regeneration that generates power from the external force is also possible.

[0046] As described above, the linear motor 1 comprises a field magnet F and an armature E capable of reciprocating in the longitudinal direction of the field magnet F. The field magnet F is configured to include a guide member 2 having a sliding surface 23 opposite the armature E along which the armature E slides, and formed by alternately stacking multiple magnetic path forming portions 21 made of soft magnetic material and non-magnetic path forming portions 22 made of non-magnetic material along the longitudinal direction, a plurality of first permanent magnets 3a, 3b arranged on the anti-armature side of the non-magnetic path forming portions 22 of the guide member 2 and magnetized along the longitudinal direction of the field magnet F, and a plurality of yokes 4 made of soft magnetic material arranged on the anti-armature side of the magnetic path forming portions 21 of the guide member 2 and between adjacent first permanent magnets 3a, 3b.

[0047] In the linear motor 1 configured in this manner, the first permanent magnets 3a, 3b are disposed on the anti-armature side of the non-magnetic path forming portion 22 of the guide member 2, and are disposed between the yokes 4, 4 disposed on the anti-armature side of the magnetic path forming portion 21 of the guide member 2, so that the first permanent magnets 3a, 3b are protected by the guide member 2 while reducing the short-circuiting magnetic flux passing between the first permanent magnets 3a, 3b and the armature E to short-circuit between the magnetic poles, and the magnetic flux of the first permanent magnets 3a, 3b can pass to the armature E side via the yoke 4 and the magnetic path forming portion 21, and the armature E can be disposed in close proximity to the field magnet F by providing the guide member 2 with the sliding surface 23 on which the armature E slides, so that a large magnetic field can be applied to the armature E to improve the thrust. Thus, with the linear motor 1, the first permanent magnets 3a, 3b are protected without causing a decrease in thrust.

[0048] In the linear motor 1 of this embodiment, the yoke 4 is integrated with the magnetic path forming portion 21 in the guide member 2, but the guide member 2 and the yoke 4 may be separate bodies, and the magnetic path forming portion 21 and the non-magnetic path forming portion 22 may be integrated into a cylindrical guide member 2, and the yoke 4, the first permanent magnet 3a, the yoke 4, and the first permanent magnet 3b may be laminated in order to form the field magnetic flux F. Even in this case, the guide member 2 has the magnetic path forming portions 21 of soft magnetic material and the magnetic path forming portions 22 of non-magnetic material laminated in multiple layers, and has a sliding surface 23 on the armature side. The first permanent magnets 3a and 3b are arranged on the anti-armature side of the non-magnetic path forming portion 22 of the guide member 2, and the yoke 4 made of soft magnetic material can be arranged between the first permanent magnets 3a and 3b on the anti-armature side of the magnetic path forming portion 21 of the guide member 2. This makes it possible to improve the thrust by applying a large magnetic field to the armature E while protecting the first permanent magnets 3a and 3b. Therefore, according to the linear motor 1 configured in this manner, the first permanent magnets 3a, 3b can be protected without causing a decrease in thrust.

[0049] Furthermore, in the linear motor 1 of this embodiment, the magnetic path forming portion 21 and the non-magnetic path forming portion 22 of the guide member 2 are integrated in a state where they are alternately stacked, and the yoke 4 is integrated with the magnetic path forming portion 21 of the guide member 2. In the linear motor 1 configured in this manner, since the guide member 2 and the yoke 4 are integrated, the yoke 4 can be provided in advance on the guide member 2 at an equal pitch, and even if there is variation in the length dimension of the first permanent magnets 3a, 3b, errors are not stacked, and the first permanent magnets 3a, 3b can be appropriately arranged on the outer periphery of the non-magnetic path forming portion 22. Furthermore, the guide member 2 and the yoke 4 are integrated to form one part, and there is no misalignment between the magnetic path forming portion 21 and the non-magnetic path forming portion 22 in the guide member 2, making it easier to form a sliding surface, and the bending rigidity is increased, making it possible to suppress the application of bending moment to the first permanent magnets 3a, 3b.

[0050] 4, the length of the first permanent magnets 3a, 3b along the longitudinal direction of the field F may be longer than the length of the non-magnetic non-magnetic path forming portion 32 along the longitudinal direction of the field F, and the first permanent magnets 3a, 3b may be in contact with the magnetic path forming portions 31 on both sides of the non-magnetic non-magnetic path forming portion 32 in the guide member 2A. According to the linear motor 1 configured in this manner, when the magnetic path forming portion 31 and the non-magnetic path forming portion 32 are laminated and joined to manufacture the guide member 2, even if there is an error in the length dimension of the magnetic path forming portion 31 and the non-magnetic path forming portion 32 in the longitudinal direction of the field F, the length of the non-magnetic path forming portion 32 is shorter than the length of the first permanent magnets 3a, 3b, so that the non-magnetic path forming portion 32 can be accommodated within the entire length of the first permanent magnets 3a, 3b.

[0051] Incidentally, even in the case where the sleeve S is manufactured by forming the annular groove G on the outer periphery of the cylindrical body T by cutting or the like after manufacturing the cylindrical body T as described above, the length of the non-magnetic-path-forming portion 32 that houses the first permanent magnets 3a, 3b is shorter than the length of the annular groove G, so that the non-magnetic-path-forming portion 32 can be contained within the entire length of the annular groove G. Therefore, the armature side surfaces of the first permanent magnets 3a, 3b housed in the annular groove G face the non-magnetic-path-forming portion 32 with certainty, and both ends of the armature side surfaces of the first permanent magnets 3a, 3b face the magnetic-path-forming portion 31, respectively.

[0052] Furthermore, when forming the annular groove G on the outer periphery of the cylindrical body T, the magnetic path forming portion 31 is also cut out, so that the yoke 4 is also made only of a soft magnetic material.

[0053] Therefore, since the yoke 4 is reliably positioned on the anti-armature side of the magnetic path forming portion 31, and the first permanent magnets 3a, 3b are reliably positioned on the anti-armature side of the magnetic path forming portion 32, the linear motor 1 can reliably apply a large magnetic field to the armature E, thereby improving thrust.

[0054] 5 in the second modified example of the linear motor 1 of the embodiment, if the yoke 4 is disposed on the anti-armature side of the magnetic path forming portion 33 made of soft magnetic material in the guide member 2B, the length of the magnetic path forming portion 33 in the longitudinal direction of the field F may be shorter than the longitudinal length of the field F2 of the yoke 4 between the first permanent magnets 3a, 3b, and a part of the yoke 4 may be disposed on the anti-armature side of the non-magnetic path forming portion 34 made of non-magnetic material. Linear motor 1B configured in this manner can also have a large magnetic field applied to the armature E, improving thrust.

[0055] Further, as in the field magnet F3 of the third modified example of the linear motor 1 of the embodiment shown in Fig. 6, radially magnetized second permanent magnets 3c, 3d magnetized along the direction toward the armature E may be provided between the first permanent magnets 3a, 3b magnetized in the longitudinal direction of the field magnet F on the anti-armature side of the magnetic path forming portion 41 formed of a soft magnetic material of the guide member 2C, instead of the yoke 4. More specifically, the radially magnetized second permanent magnet 3c with its N pole facing the armature side is disposed between the first permanent magnets 3a, 3b with their N poles facing each other, and the radially magnetized second permanent magnet 3c with its S pole facing the armature side is disposed between the first permanent magnets 3a, 3b with their S poles facing each other, and the first permanent magnets 3a, 3b and the second permanent magnets 3c, 3d are arranged in a Halbach array that concentrates the magnetic field on the armature side. In addition, when the first permanent magnets 3a, 3b and the second permanent magnets 3c, 3d are arranged in a Halbach array to form the field magnet F3, it is preferable to provide a back yoke 50 made of a soft magnetic material on the anti-armature side of the first permanent magnets 3a, 3b and the second permanent magnets 3c, 3d. By providing the back yoke 50, even if the axial length of the first permanent magnets 3a, 3b is shortened, a magnetic path with low magnetic resistance can be secured on the anti-armature side of the first permanent magnets 3a, 3b, and an increase in magnetic resistance can be suppressed, so that the thrust of the cylindrical linear motor 1 can be effectively improved when the axial length of the second permanent magnets 3c, 3d is lengthened. In addition, the thickness of the back yoke 50 may be set to a thickness suitable for suppressing an increase in the external magnetic resistance of the first permanent magnets 3a, 3b.

[0056] The axially magnetized first permanent magnets 3a, 3b are arranged on the anti-armature side of the non-magnetic non-magnetic path forming portion 42 in the guide member 2C, and the radially magnetized second permanent magnets 3c, 3d are arranged on the anti-armature side of the magnetic path forming portion 41 made of a soft magnetic material in the guide member 2C.

[0057] When the first permanent magnets 3a, 3b and the second permanent magnets 3c, 3d are arranged in a Halbach array, the second permanent magnets 3c, 3d magnetized in the direction toward the armature E become main poles, and the first permanent magnets 3a, 3b magnetized in the longitudinal direction of the field F become sub poles. Since a longer main pole in the longitudinal direction of the field F can exert a larger magnetic field on the armature E, the axial length of the second permanent magnets 3c, 3d serving as main poles is made longer than the axial length of the first permanent magnets 3a, 3b serving as sub poles, and correspondingly, the axial length of the magnetic path forming portion 41 in the guide member 2C is made equal to the axial length of the second permanent magnets 3c, 3d, and the axial length of the non-magnetic path forming portion 42 is made equal to the axial length of the first permanent magnets 3a, 3b.

[0058] In this way, even in the linear motor 1 equipped with the field magnet F3 of the third modified example, the axially magnetized permanent magnets 3a, 3b are arranged on the anti-armature side of the non-magnetic non-magnetic path forming portion 42 of the guide member 2C, and the radially magnetized second permanent magnets 3c, 3d are arranged on the anti-armature side of the magnetic path forming portion 41 of the soft magnetic material of the guide member 2C, so that while suppressing the generation of short-circuit magnetic flux passing through the armature-side non-magnetic path forming portion 42 of the first permanent magnets 3a, 3b, the magnetic flux can be efficiently directed from the second permanent magnets 3c, 3d through the magnetic path forming portion 41 to the armature E by the Halbach arrangement, and a large magnetic field can be applied to the armature E. In this way, even if the second permanent magnets 3c, 3d are provided between the first permanent magnets 3a, 3b instead of the yoke 4, a large magnetic field can be applied to the armature E while protecting the first permanent magnets 3a, 3b and the second permanent magnets 3c, 3d, improving the thrust. Therefore, according to the linear motor 1 configured in this manner, the first permanent magnets 3a, 3b and the second permanent magnets 3c, 3d can be protected without causing a decrease in thrust.

[0059] Although the linear motor 1 is described above as a cylindrical linear motor, it may be a linear motor in which the fields F, F1, F2, F3 and the armature E are flat plate-like and arranged parallel to each other. When the field F3 is flat, the second permanent magnets 3c, 3d only need to be magnetized along a direction perpendicular to the surface facing the armature E and perpendicular to the longitudinal direction of the field F3.

[0060] Furthermore, the manufacturing method of the linear motor 1 in this embodiment is a manufacturing method of a linear motor 1 that is cylindrical and has a field magnet F in which multiple magnetic path forming portions 21 made of soft magnetic material and multiple non-magnetic path forming portions 22 made of non-magnetic material are alternately stacked and integrated along the longitudinal direction, having a sliding surface 23 on its inner circumference, and in which first permanent magnets 3a, 3b are attached to its outer circumference, and includes a joining process for manufacturing a cylindrical body T by joining multiple annular base materials A made of a soft magnetic material and multiple annular base materials B made of a non-magnetic material in an alternately stacked state, a polishing process for polishing the inner surface of the cylindrical body T to form the sliding surface 23, and a groove forming process for forming multiple annular grooves G on the outer circumference of the cylindrical body T, in which the first permanent magnets 3a, 3b are attached.

[0061] According to the manufacturing method of the linear motor 1 configured in this manner, the guide member 2 and the yoke 4 can be molded integrally, and the annular groove G for accommodating the first permanent magnets 3a, 3b can be formed in advance in the sleeve S at an equal pitch, so that even if there is variation in the length dimension of the first permanent magnets 3a, 3b, errors are not accumulated and the first permanent magnets 3a, 3b can be appropriately positioned on the outer periphery of the non-magnetic path forming portion 22. Thus, according to the manufacturing method of the linear motor 1 of this embodiment, it is possible to manufacture a linear motor 1 that has a sliding surface 23 and can be positioned in close proximity to the armature E, can reduce short-circuit magnetic flux, and can apply a large magnetic field to the armature E.

[0062] Although the preferred embodiment of the present invention has been described in detail above, modifications, variations and changes can be made without departing from the scope of the appended claims. [Explanation of symbols]

[0063] 1 linear motor, 2, 2A, 2B, 2C guide member, 21, 31, 33, 41 magnetic path forming portion, 22, 32, 34, 42 non-magnetic path forming portion, 23 sliding surface, 3a, 3b first permanent magnet, 3c, 3d second permanent magnet, 4 yoke, A annular base material formed of a soft magnetic material, B annular base material formed of a non-magnetic material, E armature, F, F1, F2, F3 field magnet, G annular groove, S sleeve, T cylindrical body

Claims

1. With the field magnet, an armature capable of reciprocating in a longitudinal direction of the field magnet, The field magnet is a guide member having a sliding surface facing the armature on which the armature slides, the guide member being formed by alternately laminating a plurality of magnetic path forming portions made of soft magnetic material and non-magnetic path forming portions made of non-magnetic material along a longitudinal direction; a plurality of first permanent magnets that are arranged on the opposite side to the armature of the non-magnetic path forming portion of the guide member and are magnetized along a longitudinal direction of the field magnet; a plurality of yokes made of soft magnetic material that are respectively arranged between adjacent first permanent magnets on the anti-armature side of the magnetic path forming portion of the guide member, or second permanent magnets that are respectively arranged between adjacent first permanent magnets on the anti-armature side of the magnetic path forming portion of the guide member and are magnetized in a direction facing the armature. A linear motor characterized by:

2. a length of the permanent magnet along the longitudinal direction of the field magnet is longer than a length of the non-magnetic path forming portion along the longitudinal direction of the field magnet, The permanent magnet is in contact with the magnetic path forming portions on both sides of the non-magnetic path forming portion of the guide member.

2. The linear motor according to claim 1 .

3. The magnetic path forming portions and the non-magnetic path forming portions of the guide member are integrated in a state in which a plurality of the magnetic path forming portions and the non-magnetic path forming portions are alternately stacked, The yokes are each integral with the corresponding magnetic path forming portion in the guide member.

3. The linear motor according to claim 1 or 2.

4. A method for manufacturing a linear motor having a cylindrical shape, a plurality of soft magnetic bodies and non-magnetic bodies alternately laminated and integrated along a longitudinal direction, a sliding surface on an inner circumference, and a field magnet having a permanent magnet attached on an outer circumference, comprising: a joining step of manufacturing a cylindrical body by joining a plurality of annular base materials formed of the soft magnetic material and a plurality of annular base materials formed of the non-magnetic material in an alternating stacked state; a polishing step of polishing an inner circumferential surface of the cylindrical body to form the sliding surface; a groove forming step of forming a plurality of annular grooves in which the permanent magnets are to be mounted on the outer periphery of the cylindrical body. A method for manufacturing a linear motor comprising the steps of:

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