JP2023104143A - Cylindrical linear motor - Google Patents

Abstract

To provide a cylindrical linear motor which can further reduce cogging thrust.SOLUTION: A cylindrical linear motor 1 comprises: a field magnet 6 in which N poles and S poles are alternately arranged in an axial direction; and an armature E which can move in the axial direction with respect to the field magnet 6. The armature E includes: a cylindrical core 2 which is a magnetic body; and windings 3 attached to the core 2. The core 2 includes: a plurality of teeth 2b with trapezoidal axial cross sections; a slot 2c to which the windings 3 are attached; auxiliary salient poles 2e1 and 2e2 provided on end sides of teeth 2b1 and 2b2 at both axial ends; and chamfered parts 2d1 and 2d2 provided around a field magnet side on end sides of the auxiliary salient poles 2e1 and 2e2. An axial length X of end faces 2b11, 2b21, 2e11 and 2e21 of the teeth 2b1 and 2b2 and the auxiliary salient poles 2e1 and 2e2 in both ends, which face the field magnet 6, is set to reduce cogging thrust by the core 2 with cogging thrust by the auxiliary salient poles 2e1 and 2e2 of the core 2.SELECTED DRAWING: Figure 1

Description

The present invention relates to cylindrical linear motors.

A cylindrical linear motor is mounted, for example, in a slot between a core having a cylindrical stator case and a plurality of teeth arranged on the inner circumference of the stator case and arranged axially on the inner circumference. and a stator having U-phase, V-phase and W-phase windings, and a mover having a plurality of permanent magnets provided on the outer periphery thereof.

In the tubular linear motor constructed in this manner, the core is smoothed to change the magnetic flux at both ends of the core to reduce the cogging thrust generated when the mover moves in the axial direction with respect to the stator. Auxiliary salient poles are provided at both ends in the axial direction (see Patent Document 1, for example).

JP 2006-187079 A

In such a cylindrical linear motor, the cogging thrust due to the end effect can be reduced by providing auxiliary salient poles, but the cogging thrust due to the core contains harmonic components, so the cogging thrust cannot be sufficiently reduced. Therefore, further reduction of cogging thrust is desired. Note that the cogging thrust by the core refers to a non-uniform force generated because the shape of the teeth at the ends of the core is different from the shape of the teeth in the intermediate part of the core. natural number).

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a cylindrical linear motor capable of further reducing cogging thrust.

In order to achieve the above object, the cylindrical linear motor of the present invention comprises a magnetic field in which north poles and south poles are arranged alternately in the axial direction, and an armature that is axially movable with respect to the magnetic field. The armature has a magnetic cylindrical core and windings attached to the core. A plurality of teeth having a trapezoidal cross-section in the axial direction are provided annularly along the circumferential direction, slots in which windings formed by the gaps between the teeth are mounted, and tooth end sides at both ends in the axial direction and an auxiliary salient pole provided on the end side of the auxiliary salient pole and a chamfered portion provided over the periphery of the field side on the end side of the auxiliary salient pole and spaced away from the field side toward the end side, and teeth at both ends and The axial length of the end faces of the auxiliary salient poles facing the magnetic field at regular intervals is set so that the cogging thrust of the core is reduced by the cogging thrust of the auxiliary salient poles of the core.

In the cylindrical linear motor configured in this manner, the core has teeth with a trapezoidal cross section, and the core has chamfered portions on the auxiliary salient poles on both ends in the axial direction. The waveform of the cogging thrust due to the auxiliary salient pole becomes a sine waveform with little distortion. In addition, since the axial length of the teeth at both ends and the end faces of the auxiliary salient poles facing the magnetic field are set so that the cogging thrust of the core is reduced by the cogging thrust of the auxiliary salient poles of the core, there is little distortion. The phases of the cogging thrust by the sinusoidal core and the cogging thrust by the auxiliary salient poles of the core can be adjusted by setting the length so that the thrusts cancel each other out.

Further, the core in the cylindrical linear motor includes a center core segment including teeth on both ends in the axial direction, a pair of ring-shaped spacers laminated on both ends of the center core segment in the axial direction, and a ring-shaped core. and a pair of end-side core segments laminated on the opposite side of the central core segment in the axial direction of the spacer and having the chamfered portions, the spacer and the end-side core segments functioning as auxiliary salient poles. may According to the tubular linear motor constructed in this manner, the end portion of the central core divided body is provided so that the cogging thrust due to the core and the cogging thrust due to the auxiliary salient pole of the core can be efficiently canceled by exchanging the spacer. The axial position of the side core segments can be adjusted.

Further, the core in the cylindrical linear motor includes a central core segment including teeth on both ends in the axial direction, and a pair of annular ends provided with chamfered portions which are laminated on both ends in the axial direction of the central core segment. and the edge-side core segments, and the end-side core segments may function as auxiliary salient poles. According to the tubular linear motor constructed in this way, if the end side core split body having the optimum axial length according to the number of pole slots of the tubular linear motor is used, the design of the center core split body can be changed. Therefore, the cogging thrust due to the core and the cogging thrust due to the auxiliary salient pole of the core can be efficiently canceled out.

In the cylindrical linear motor, the axial length of the teeth on both ends and the end faces of the auxiliary salient poles facing the magnetic field is such that the phase of the cogging thrust by the core and the phase of the cogging thrust by the auxiliary salient poles of the core are 180 degrees. may be set to be According to the cylindrical linear motor constructed in this manner, the waveform of the cogging thrust from the core and the waveform of the cogging thrust from the auxiliary salient poles of the core are exactly opposite in phase, and cancel each other out efficiently. The overall cogging thrust of the motor can be minimized.

According to the tubular linear motor of the present invention, cogging thrust can be further reduced.

1 is a longitudinal sectional view of a cylindrical linear motor in one embodiment; FIG. 4 is a partially enlarged view of the armature of the cylindrical linear motor of one embodiment; FIG. FIG. 4 is a diagram showing a waveform of cogging thrust by the core, a waveform of cogging thrust by the auxiliary salient poles of the core, and a waveform of cogging thrust of the entire cylindrical linear motor. FIG. 10 is a vertical cross-sectional view of a core of a cylindrical linear motor in a first modified example of one embodiment;

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on embodiments shown in the drawings. As shown in FIG. 1, a tubular linear motor 1 according to one embodiment includes a tubular magnetic field 6 in which north poles and south poles are alternately arranged in the axial direction, and a tubular core 2. It comprises an armature E having windings 3 mounted on a core 2 .

Each part of the cylindrical linear motor 1 will be described in detail below. In the present embodiment, the magnetic field 6 is formed in a cylindrical shape by including an annular main pole permanent magnet 6a and an annular auxiliary pole permanent magnet 6b which are alternately stacked in the axial direction and inserted. ing. A cylindrical back yoke 8 is attached to the outer circumference of the field magnet 6 . The magnetic field 6 and the back yoke 8 are accommodated in an annular gap formed between a cylindrical non-magnetic outer tube 7 and a cylindrical non-magnetic inner tube 9 inserted into the outer tube 7. It is

In FIG. 1, the triangular marks on the main magnetic pole permanent magnet 6a and the auxiliary magnetic pole permanent magnet 6b indicate the magnetization direction, and the magnetization direction of the main magnetic pole permanent magnet 6a is the radial direction. , and the magnetization direction of the permanent magnet 6b of the secondary magnetic pole is the axial direction. The main magnetic pole permanent magnet 6a and the auxiliary magnetic pole permanent magnet 6b are arranged in a Halbach array. .

Further, the axial length L1 of the main pole permanent magnet 6a is longer than the axial length L2 of the subsidiary pole permanent magnet 6b. The axial length L1 of the permanent magnet 6a of the main pole and the axial length L2 of the permanent magnet 6b of the sub-magnetic pole are set so as to satisfy .5. If the axial length L1 of the main pole permanent magnet 6a is lengthened, the magnetic resistance between the main pole permanent magnet 6a and the core 2 can be reduced, and the magnetic field acting on the core 2 can be increased. The mass thrust density of the motor 1 can be improved.

Further, in the tubular linear motor 1 of the present embodiment, a back yoke 8 is provided around the outer peripheries of the permanent magnets 6a and 6b. Without the back yoke 8, when the axial length L2 of the permanent magnet 6b of the secondary magnetic pole is shortened, the magnetic resistance outside the magnet at the central portion of the permanent magnet 6a of the main magnetic pole in the axial direction increases, and the field magnetic flux decreases. Therefore, the degree of improvement in the thrust force of the cylindrical linear motor 1 when the axial length L1 of the permanent magnet 6a of the main magnetic pole is lengthened is reduced. On the other hand, if the back yoke 8 is provided on the outer periphery of the permanent magnets 6a and 6b, it is possible to secure a magnetic path with low magnetic resistance. Growth is suppressed. Therefore, if the axial length L1 of the permanent magnet 6a of the main magnetic pole is made longer than the axial length L2 of the permanent magnet 6b of the sub-magnetic pole and a cylindrical back yoke 8 is provided on the outer periphery of the permanent magnets 6a and 6b, the cylindrical The mass thrust density of the linear motor 1 can be greatly improved. The thickness of the back yoke 8 may be set to a thickness suitable for suppressing an increase in the external magnetic resistance of the permanent magnet 6a of the main magnetic pole.

The secondary magnetic pole permanent magnet 6b is a permanent magnet having a coercive force higher than that of the main magnetic pole permanent magnet 6a. Residual magnetic flux density and coercive force in a permanent magnet are closely related to each other. in a relationship. In the Halbach arrangement, since a large magnetic field is applied to the permanent magnet 6b of the secondary magnetic pole in the direction of demagnetization, the coercive force of the permanent magnet 6b of the secondary magnetic pole is increased to suppress demagnetization, and a large magnetic field acts on the core 2. I am trying to make it possible. On the other hand, the strength of the magnetic field acting on the core 2 depends on the number of lines of magnetic force of the permanent magnet 6a of the main magnetic pole. Therefore, a permanent magnet with a high residual magnetic flux density is used as the permanent magnet 6a of the main magnetic pole so that a large magnetic field acts on the core 2. FIG. In the present embodiment, when making the coercive force of the permanent magnet 6b of the secondary magnetic pole higher than that of the permanent magnet 6a of the main magnetic pole, the material of the permanent magnet 6b of the secondary magnetic pole has a higher coercive force than the material of the permanent magnet 6a of the main magnetic pole. is a high-quality material. Therefore, the combination of the main pole permanent magnet 6a and the subsidiary pole permanent magnet 6b can be easily realized by selecting materials. In the present embodiment, the permanent magnet 6a of the main magnetic pole is made of a material having a high residual magnetic flux density, the main components of which are neodymium, iron, and boron. It is composed of a magnet that is difficult to demagnetize by increasing the amount of heavy rare earth elements such as.

A core 2 is inserted on the inner peripheral side of the stator, and the magnetic field system 6 applies a magnetic field to the core 2 . Since the magnetic field system 6 may apply a magnetic field to the movable range of the core 2, the installation range of the permanent magnets 6a and 6b may be determined according to the movable range of the core 2. FIG. Therefore, the permanent magnets 6a and 6b do not need to be installed in a range of the annular gap between the outer tube 7 and the inner tube 9 that cannot face the core 2. As shown in FIG. In the present embodiment, the magnetic field 6 is composed of permanent magnets 6a and 6b laminated in a Halbach arrangement, but since it is sufficient if N poles and S poles appear alternately on the inner periphery, any magnet other than the Halbach arrangement may be used. may consist of permanent magnets stacked in an array of

The left ends of the outer tube 7, back yoke 8 and inner tube 9 in FIG. is blocked.

The armature E includes a cylindrical core 2 and windings 3 attached to the core 2, and is inserted into the inner tube 9 so as to be axially movable. That is, in the present embodiment, the armature E is arranged on the inner peripheral side of the magnetic field 6 and can move relative to the magnetic field 6 in the axial direction.

In the present embodiment, the core 2 is made of a permendur material, and includes a cylindrical yoke 2a and an annular outer periphery on the field side of the yoke 2a along the circumferential direction and in the axial direction. A plurality of teeth 2b having a trapezoidal cross section in the axial direction provided at intervals, a slot 2c formed by the gap between the teeth 2b and 2b and in which the winding 3 is mounted, and the core 2 of the teeth 2b Auxiliary salient poles 2e1 and 2e2 provided on axial end sides of the teeth 2b1 and 2b2 at both ends in the axial direction, and a chamfered portion 2d1 provided around the outer peripheries on the field side of the auxiliary salient poles 2e1 and 2e2. , 2d2.

The yoke 2a has a cylindrical shape as described above, and its cross-sectional area is a cylinder centered on the axis of the core 2, and the teeth 2b are cut by the cylinder wherever the teeth 2b are cut from the inner circumference to the outer circumference. The thickness is ensured so that it is larger than the area of the cross section that is actually formed.

In this embodiment, as shown in FIGS. 1 and 2, 13 teeth 2b are arranged on the outer circumference of the yoke 2a at equal intervals in the axial direction, and the outer circumference on the field 6 side of the core 2 is provided. A slot 2c is formed between the teeth 2b, 2b and is an annular groove in which the winding 3 is mounted. In the present embodiment, the tooth 2b has a trapezoidal cross-sectional shape, and the width of the base end side, which is the inner circumference, is larger than the width of the tip side, which is the outer circumference, to increase the cross-sectional area of the magnetic path on the base end side. I have secured. More specifically, each tooth 2b has a trapezoidal cross section, but the teeth 2b other than the teeth 2b1 and 2b2 arranged at both axial ends of the core 2 have an isosceles trapezoidal shape. In the present embodiment, the teeth 2b1 and 2b2 arranged at both ends in the axial direction of the core 2 have a cross-sectional shape in which the teeth 2b are halved at the center in the axial direction. The width is half the axial width Y of the outer periphery of the tooth 2b. Therefore, in the present embodiment, the auxiliary salient poles 2e1 and 2e2 are formed at both ends of the core 2 from the point Y/2 from the slot 2c side end of the teeth 2b1 and 2b2 at the end of the core 2, It is made integral with the teeth 2b1 and 2b2 at the ends. In addition, although the axial width of the outer periphery of the end tooth 2b is set to Y/2, it can be changed arbitrarily.

In this embodiment, a total of 12 slots 2c, which are annular grooves, are provided between adjacent teeth 2b, 2b in FIG. A plurality of slots 2c are provided along the circumferential direction of the core 2, and are arranged on the outer circumference of the core 2 at equal pitches in the axial direction.

A wire 3 is wound and mounted in the slot 2c. The winding 3 is a three-phase winding of U-phase, V-phase and W-phase. The windings 3 of each phase are mounted in the 12 slots 2c so as to be arranged appropriately according to the magnetic pole arrangement of the field system 6. As shown in FIG.

1 and 2, the core 2 is located on the outer peripheral side of the auxiliary salient poles 2e1 and 2e2 provided on the ends of the teeth 2b1 and 2b2 provided on both ends in the axial direction and on the field side. are provided with chamfered portions 2d1 and 2d2 provided by chamfering the peripheries thereof in an R shape.

The armature E configured in this way is mounted on the outer circumference of the tip of the rod 11 which is the output shaft and is made of a non-magnetic material, and is movably inserted into the magnetic field 6 together with the rod 11 . In the tubular linear motor 1 of the present embodiment, the magnetic field 6 and the armature E configured as described above constitute an 8-pole 9-slot linear motor. Note that the combination of the number of poles and the number of slots can be changed as appropriate.

The rod 11 protrudes out of the cylindrical linear motor 1 through a head cap 15 attached to the right end of the outer tube 7 in FIG. Sliders 12 and 13 are mounted on the left and right sides of the armature E of the rod 11 in FIG. Armature E is sandwiched between sliders 12 and 13 and core 2 is fixed to rod 11 . Further, since the sliders 12 and 13 are in sliding contact with the inner circumference of the inner tube 9, the armature E does not wobble with respect to the magnetic field 6, so that it can move in the axial direction without interfering with the inner tube 9.

In this way, the inner tube 9 forms a high magnetic resistance gap between the outer circumference of the core 2 and the inner circumference of the field magnet 6, and cooperates with the sliders 12 and 13 to move the armature E in the axial direction. play a role in guiding The outer diameter of the core 2 is smaller than the inner diameter of the inner tube 9 so that it does not interfere with the inner tube 9 and the cylindrical linear motor 1 can extend and contract smoothly. . Although the inner tube 9 may be made of a non-magnetic material, if it is made of a synthetic resin, the effect of improving the thrust density of the cylindrical linear motor 1 will be enhanced. If the inner tube 9 is made of non-magnetic metal, an eddy current is generated inside the inner tube 9 when the armature E moves in the axial direction, generating a force that prevents the armature E from moving. On the other hand, if the inner tube 9 is made of synthetic resin, no eddy current is generated, so the thrust of the cylindrical linear motor 1 can be more effectively improved and the mass of the cylindrical linear motor 1 can be reduced. When the inner tube 9 is made of synthetic resin, the friction and wear between the inner tube 9 and the sliders 12 and 13 can be reduced by making it from fluorine resin. In addition, the inner tube 9 may be made of other synthetic resins, and the inner circumference of the inner tube 9 made of other synthetic resins may be coated with fluororesin to reduce friction and wear.

Although not shown, the rod 11 has a cylindrical shape, and electric power is supplied from an external power source installed outside the cylindrical linear motor 1 to the winding 3 through an electric wire (not shown) that is passed through the rod 11 . can supply.

Then, for example, by sensing the electrical angle of the windings 3 with respect to the magnetic field 6, switching the energization phase based on the electrical angle, and controlling the current amount of each winding 3 by PWM control, the cylindrical linear motor 1 and the moving direction of the armature E can be controlled. Note that the control method described above is an example and is not limited to this. Further, when an external force acts to relatively displace the armature E and the magnetic field 6 in the axial direction, the energization of the winding 3 or the induced electromotive force generated in the winding 3 produces a thrust that suppresses the relative displacement. can be generated to cause the cylindrical linear motor 1 to damp vibrations and motions of the equipment due to the external force, and energy regeneration to generate electric power from the external force is also possible.

In cylindrical linear motor 1 of the present embodiment, core 2 includes teeth 2b having a trapezoidal cross section. Thus, when the core 2 is provided with teeth 2b having a trapezoidal cross section, the lines of magnetic force from the magnetic field 6 side reach not only the outer peripheral ends of the teeth 2b but also the side surfaces of both axial ends of the teeth 2b. As shown in waveform A, the waveform of the cogging thrust by the core 2 is closer to a sinusoidal waveform with suppressed harmonic distortion compared to the conventional tubular linear motor that uses a tooth core with a rectangular cross section. becomes. The period of the cogging thrust by the core 2 is determined by the number of slots and the number of poles. It is 5 degrees, which is the value obtained by dividing by the lowest common multiple.

Further, in the cylindrical linear motor 1 of the present embodiment, the auxiliary salient poles 2e1 and 2e2 provided at the ends of the teeth 2b1 and 2b2 at both ends of the core 2 in the axial direction are provided at the ends of the outer circumferences on the field side. Chamfered portions 2d1 and 2d2 are provided on the periphery, which are spaced apart from the magnetic field 6 toward the ends. In this way, if the core 2 is provided with the chamfered portions 2d1 and 2d2 on the auxiliary salient poles 2e1 and 2e2 at both ends in the axial direction so as to move away from the magnetic field 6, the change in the magnetic flux at both ends in the axial direction of the armature E As shown in waveform B in FIG. 3, the waveform of the cogging thrust due to the auxiliary salient poles 2e1 and 2e2 of the core 2 is higher in pitch than in a conventional cylindrical linear motor having no chamfer. The distortion of the wave is suppressed and the waveform becomes close to a sinusoidal waveform. Here, the cogging thrust due to the auxiliary salient poles of the core 2 is the force acting on the open surfaces of the auxiliary salient poles 2e1 and 2e2, and the waveform distortion is reduced by the shape of the chamfered portions 2d1 and 2d2 of the auxiliary salient poles 2e1 and 2e2. The phase can be adjusted by setting the axial length (thickness) from the slot 2c side ends of the teeth 2b1 and 2b2 to the chamfered portions 2d1 and 2d2 of the auxiliary salient poles 2e1 and 2e2.

As described above, in the cylindrical linear motor 1 of the present embodiment, the core 2 is provided with the teeth 2b having a trapezoidal cross section, so that the cogging thrust due to the core 2 has a sinusoidal waveform with little distortion, and the core 2 moves in the axial direction. Since the chamfered portions 2d1 and 2d2 are provided on the auxiliary salient poles 2e1 and 2e2 at both ends of the core 2, the waveform of the cogging thrust due to the auxiliary salient poles 2e1 and 2e2 of the core 2 becomes a sinusoidal waveform with little distortion.

In this way, both the cogging thrust by the core 2 and the cogging thrust by the auxiliary salient poles 2e1 and 2e2 of the core 2 have waveforms close to sinusoidal waveforms. , 2e2, the overall cogging thrust of the cylindrical linear motor 1 can be suppressed.

Therefore, in the cylindrical linear motor 1 of the present embodiment, the end faces 2b11 and 2b21 of the teeth 2b1 and 2b2 at both ends facing the magnetic field 6 and the end faces 2e11 and 2e21 of the auxiliary salient poles 2e1 and 2e2 facing the magnetic field 6 are The axial length X is set so that the cogging thrust by the core 2 can be reduced by the cogging thrust by the auxiliary salient poles 2e1 and 2e2 of the core 2. FIG. Specifically, the distance between the magnetic field 6 of the core 2 and the chamfered portion 2d1 (2d2) of the auxiliary salient pole 2e1 (2e2) is the shortest. On the other hand, when the total axial length X of the end face 2b11 (2b21) and the end face 2e11 (2e21) facing each other at a constant interval is changed, the phase of the waveform of the cogging thrust due to the auxiliary salient poles 2e1 and 2e2 of the core 2 changes to the core 2 can adjust the phase and difference of the cogging thrust waveform. Therefore, in the cylindrical linear motor 1 of the present embodiment, the difference between the phase of the cogging thrust waveform by the core 2 and the phase of the cogging thrust waveform by the auxiliary salient poles 2e1 and 2e2 of the core 2 is The angle is set to 180 degrees so that the cogging thrust by the core 2 and the cogging thrust by the auxiliary salient poles 2e1 and 2e2 of the core 2 cancel each other out. More specifically, in the cylindrical linear motor 1 of the present embodiment, the length X is set to a half of the magnetic pole pitch, and as shown in FIG. The thrust waveform A and the cogging thrust waveform B due to the auxiliary salient poles 2e1 and 2e2 of the core 2 appear with a phase difference of 180 degrees and cancel each other out, so that the entire cogging thrust waveform C of the cylindrical linear motor 1 is maximized. can be made smaller.

In order to minimize the cogging thrust of the entire cylindrical linear motor 1, the difference between the phase of the cogging thrust waveform A by the core 2 and the phase of the cogging thrust waveform B by the auxiliary salient poles 2e1 and 2e2 of the core 2 is is 180 degrees, the axial length X of the end faces 2b11 and 2b21 of the teeth 2b1 and 2b2 closest to the field 6 and the end faces 2e11 and 2e21 of the auxiliary salient poles 2e1 and 2e2 are set as follows: However, the length X can be freely set as long as the cogging thrust of the cylindrical linear motor 1 as a whole can be reduced.

As described above, the cylindrical linear motor 1 of the present embodiment includes the magnetic field 6 in which the N poles and the S poles are alternately arranged in the axial direction, and the armature E movable in the axial direction with respect to the magnetic field 6. The armature E has a cylindrical magnetic core 2 and windings 3 attached to the core 2. The core 2 is annularly provided on the outer periphery along the circumferential direction. A plurality of teeth 2b having a trapezoidal cross-section in the axial direction, slots 2c in which windings 3 formed by gaps between the teeth 2b and 2b are mounted, and teeth 2b1 and 2b2 at both ends in the axial direction. and chamfered portions 2d1 and 2d2 provided around the end sides of the auxiliary salient poles 2e1 and 2e2 on the magnetic field side and spaced away from the magnetic field 6 toward the end sides. The axial length X of the end faces 2b11, 2b21, 2e11, 2e21 of the teeth 2b1, 2b2 and the auxiliary salient poles 2e1, 2e2 facing the magnetic field 6 at regular intervals determines the cogging thrust of the core 2 to the auxiliary salient poles of the core 2. It is set to be reduced by cogging thrust by 2e1 and 2e2.

In the tubular linear motor 1 configured as described above, the core 2 includes teeth 2b having a trapezoidal cross section, and the core 2 includes chamfered portions 2d1 and 2d2 on the auxiliary salient poles 2e1 and 2e2 at both ends in the axial direction. Therefore, the waveforms of the cogging thrust by the core 2 and the cogging thrust by the auxiliary salient poles 2e1 and 2e2 of the core 2 are sinusoidal waveforms with little distortion. In addition, the axial length X of the end faces 2b11, 2b21, 2e11, 2e21 of the teeth 2b1, 2b2 and the auxiliary salient poles 2e1, 2e2 facing the magnetic field 6 at both ends is determined by the cogging thrust of the core 2 and the auxiliary salient poles of the core 2. Since the cogging thrust is reduced by the cogging thrust due to 2e1 and 2e2, the phase of the cogging thrust due to the sinusoidal core 2 with little distortion and the cogging thrust due to the auxiliary salient poles 2e1 and 2e2 of the core 2 is adjusted to the length X. It can be adjusted to offset each other's thrust by setting. Therefore, according to the cylindrical linear motor 1 of the present embodiment, the cogging thrust of the core 2 is reduced by the cogging thrust of the auxiliary salient poles 2e1 and 2e2 of the core 2, thereby reducing the overall cogging thrust of the cylindrical linear motor 1. can.

Furthermore, the axial length X of the end faces 2b11, 2b21, 2e11, 2e21 of the teeth 2b1, 2b2 and the auxiliary salient poles 2e1, 2e2 facing the magnetic field 6 at both ends is determined by the phase of the cogging thrust by the core 2 and the auxiliary projection of the core 2. When the phase of the cogging thrust by the poles 2e1 and 2e2 is set to be 180 degrees, the waveform A of the cogging thrust by the core 2 and the waveform B of the cogging thrust by the auxiliary salient poles 2e1 and 2e2 of the core 2 are exactly opposite. They become phases and efficiently cancel each other, so that the overall cogging thrust of the cylindrical linear motor 1 can be minimized.

Note that, like the cylindrical linear motor 1A of the first modification of the embodiment shown in FIG. , a pair of annular spacers 22, 22 stacked on both ends of the central core segment 21 in the axial direction; A pair of end-side core segments 23, 23 having chamfered portions 23a, 23a may be used, and the spacer 22 and the end-side core segments 23 may function as auxiliary salient poles. These central core segment 21, spacers 22, 22 and end core segments 23, 23 are made of a magnetic material.

The central core segment 21 includes a cylindrical yoke 21a and annular teeth 21b having a trapezoidal cross section provided on the outer circumference of the yoke 21a. , are shorter than the other teeth 21b. The winding 3 is mounted in the slots 21c formed by the gaps between the teeth 21b. The spacers 22 , 22 are ring-shaped and have their outer peripheral surfaces facing the magnetic field 6 . The end-side core segment 23 has a curved surface formed by chamfering the outer peripheral surface in an R shape, and the entire outer peripheral surface forms a chamfered portion 23a. Spacers 22, 22 are superimposed on both axial ends of central core segment 21 configured in this way, and end side core segments 23, 23 are stacked from the outer side of spacers 22, 22. A core 2 having the same shape as the core 2 in the cylindrical linear motor 1 can be formed.

The end-side core segments 23, 23 are provided with chamfers 23a, 23a in order to reduce the distortion of the cogging thrust waveform due to the auxiliary salient poles of the core 2, and the spacer 22 reduces the cogging thrust waveform of the core 2. is provided to adjust the phase of the waveform of the cogging thrust of the auxiliary salient pole of the core 2 with respect to the phase of . Here, if a plurality of spacers 22 with different axial lengths are prepared, replacement of the spacers 22 will reduce the cogging thrust force generated by the core 2 by the auxiliary salient poles of the core 2 . It is possible to adjust the positions of the end-side core segments 23 that generate cogging thrust.

Thus, the core 2 consists of a central core segment 21 including teeth 2b1 and 2b2 at both ends in the axial direction, and a pair of annular spacers laminated on both ends of the central core segment 21 in the axial direction. 22, 22, and end-side core segments 23, 23 which are annular and are laminated on the opposite side of the central core segment in the axial direction of the spacers 22, 22 and provided with chamfered portions 23a, 23a. According to the type linear motor 1A, by exchanging the spacer 22, the cogging thrust by the core 2 and the cogging thrust by the auxiliary salient pole of the core 2 can be efficiently canceled out. The axial positions of the divided bodies 23, 23 can be adjusted.

Note that the outer peripheral surface of the end-side core segment 23 may form part of the range of the length X instead of forming the entire outer peripheral surface of the end-side core segment 23 as the chamfered portion 23a. good. Moreover, the spacer 22 may be configured to include all of the outermost peripheral surfaces of the teeth 2b1 and 2b2 on both sides in the axial direction of the core 2 . In this way, the auxiliary salient poles may be constituted only by the spacers 22 and the end-side core segments 23, or the spacers 22 and the end-side core segments 23 may be used not only for the auxiliary salient poles but also for the teeth on both ends of the core 2. , or the spacer 22 and the end-side core segment 23 may constitute a part of the auxiliary salient pole.

Furthermore, although not shown, the core 2 omits the spacers 22 and 23, and includes a central core segment 21 and an end portion which is laminated on both ends of the central core segment 21 in the axial direction and has chamfers 23a and 23a. Alternatively, the end-side core segments 23 may function as auxiliary salient poles. In this case, the outer peripheral surface of the end-side core segment 23 does not entirely constitute the chamfered portion 23a, but the outer peripheral surface of the end-side core segment 23 constitutes part or all of the length X described above. You may Also, the auxiliary salient poles may be configured only by the end-side core segments 23, or the end-side core segments 23 may be used to partially or entirely configure the auxiliary salient poles and the teeth 2b1 and 2b2 at both ends of the core 2. Alternatively, the end-side core segment 23 may constitute a part of the auxiliary salient pole.
According to the cylindrical linear motor constructed in this way, if the end side core segments 23, 23 having the optimum axial length according to the number of pole slots of the cylindrical linear motor are used, the center core segment 21, the cogging thrust by the core 2 and the cogging thrust by the auxiliary salient poles 2e1 and 2e2 of the core 2 can be efficiently cancelled.

In the cylindrical linear motors 1 and 1A of the respective embodiments, the chamfered portions 2d1, 2d2, and 23a are formed by curved surfaces having R-shaped cross sections, but the teeth 2b1 and 2b2 or the end-side core split body 23 It may be formed with a C-shaped tapered surface as long as it is chamfered away from the magnetic field 6 at both ends in the axial direction of the magnetic field.

The cylindrical linear motor 1 of the present embodiment has a structure in which the armature E is provided on the inner periphery of the field system 6, but a structure in which the armature E is provided on the outer periphery of the field system 6 may be adopted. It is possible. In that case, teeth are provided on the inner peripheral side of the core 2 on the field side, and the windings 3 are mounted in the slots formed between the teeth, and the inner peripheral sides of the auxiliary salient poles at both ends in the axial direction of the core 2 A chamfered portion may be provided around the magnetic field side where In this case, the axial length of the inner peripheral surface facing the magnetic field from the slot side end of the tooth of the core to the chamfered portion of the auxiliary salient pole is It may be set so as to be reduced by thrust.

Although preferred embodiments of the invention have been described in detail above, modifications, variations, and changes are possible without departing from the scope of the claims.

Reference Signs List 1, 1A Cylindrical linear motor 2 Core 2a, 21a Yoke 2b1, 2b2 Teeth at both ends 2b11, 2b21, 2e11, 2e21 End surface 2c, 21c Slots 2d1, 2d2, 23a Chamfered portions 2e1, 2e2 Auxiliary salient poles 3 Windings 6 Fields 21 Central core segment 22 . . . Spacer 23 .. End-side core division body E, E1 .

Claims (4)

a magnetic field in which N poles and S poles are alternately arranged in the axial direction;
an armature axially movable with respect to the magnetic field;
The armature is
a cylindrical core that is magnetic;
a winding attached to the core;
The core is
a cylindrical yoke;
a plurality of teeth annularly provided along the circumferential direction on the field side of the inner circumference or the outer circumference of the yoke and having a trapezoidal cross section in the axial direction;
a slot in which the winding formed by the gap between the teeth is mounted;
Auxiliary salient poles provided on the ends of the teeth on both ends in the axial direction;
a chamfered portion that is provided on the end side of the auxiliary salient pole and extends around the field side, and that is spaced apart from the field side toward the end side;
The axial lengths of the teeth on both ends and the end faces of the auxiliary salient poles facing the magnetic field at regular intervals are set so that the cogging thrust of the core is reduced by the cogging thrust of the auxiliary salient poles of the core. A cylindrical linear motor characterized by: The core is
a central core segment including teeth on both ends in the axial direction;
a pair of annular spacers stacked on both axial ends of the central core segment;
a pair of end-side core segments each having an annular shape and being laminated on the opposite side of the central core segment in the axial direction of the spacer and having the chamfered portion;
2. The cylindrical linear motor according to claim 1, wherein the spacer and the end-side core segments function as the auxiliary salient poles. The core is
a central core segment including teeth on both ends in the axial direction;
and a pair of end-side core segments which are annular and are stacked on both ends of the central core segment in the axial direction, have the chamfered portions, and function as the auxiliary salient poles. The cylindrical linear motor according to claim 1. The axial lengths of the teeth on both ends and the end faces of the auxiliary salient poles facing the magnetic field are set so that the phase of the cogging thrust by the core and the phase of the cogging thrust by the auxiliary salient poles of the core are 180 degrees. The cylindrical linear motor according to any one of claims 1 to 3, characterized in that

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