Linear motor

Abstract

To provide a linear motor capable of efficiently driving a movable body in a cylindrical pressure vessel.SOLUTION: A linear motor that is provided in a cylindrical pressure container and drives a movable body in the pressure container includes a mover that is disposed inside the pressure container, is connected to the movable body, and is movable in a container axial direction of the pressure container along an inner peripheral surface of the pressure container, and a stator that is disposed outside the pressure container so as to face the mover across the pressure container. The mover has a magnetic pole surface that faces an inner peripheral surface of the pressure container and on which a plurality of magnets are arranged, and the stator has a coil that generates a magnetic flux for driving the mover and a stator core including a salient pole portion that protrudes toward the magnetic pole surface. The magnetic pole surface is formed in an arc shape which is concentric with the inner peripheral surface of the pressure vessel and is convex toward the pressure vessel. A distal end of the salient pole portion has an arc-shaped recessed portion that is concentric with the outer peripheral surface of the pressure container and is recessed toward the pressure container.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a linear motor that drives a movable body within a cylindrical pressure vessel. [Background technology]

[0002] Conventionally, as one of the driving means for relatively moving a movable body in a linear direction, a linear motor is known which drives a movable element in a linear direction by the magnetic force of a linearly arranged permanent magnet and an electromagnet (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-186244 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-143398 Summary of the Invention [Problem to be solved by the invention]

[0004] The application of a linear motor has been considered as a driving means for driving a movable body arranged inside a cylindrical pressure vessel in the axial direction of the vessel. For example, a linear motor in which a stator having a coil is arranged outside the vessel and a movable part having a permanent magnet is arranged inside the vessel makes it possible to drive a movable body connected to the movable part from outside the vessel without laying out coil wiring or the like inside the vessel, and is therefore preferable as a driving means for a movable body inside the pressure vessel.

[0005] In the linear motor described above, the stator is placed on the cylindrical surface of the pressure vessel, and the stator and the mover face each other via a cylindrical partition wall. Therefore, various measures are required to efficiently drive the mover inside the pressure vessel.

[0006] The present invention has been made in view of the above circumstances, and has an object to provide a linear motor that can efficiently drive a movable body within a cylindrical pressure vessel. [Means for solving the problem]

[0007] A linear motor according to one embodiment is mounted in a cylindrical pressure vessel and drives a movable body within the pressure vessel. The linear motor includes a mover disposed inside the pressure vessel and connected to the mover, movable along the inner circumferential surface of the pressure vessel in the vessel axial direction of the pressure vessel, and a stator disposed outside the pressure vessel, facing the mover across the pressure vessel. The mover faces the inner circumferential surface of the pressure vessel and has a magnetic pole surface on which a plurality of magnets are arranged. The stator includes a coil that generates magnetic flux that drives the mover and a stator core including a salient pole portion that protrudes toward the magnetic pole surface. The magnetic pole surface is formed in an arc shape that is concentric with the inner circumferential surface of the pressure vessel and convex toward the pressure vessel. The tip of the salient pole portion has an arc-shaped recess that is concentric with the outer circumferential surface of the pressure vessel and concave toward the pressure vessel.

[0008] In the above aspect, the arc length of the recess of the stator may be longer than the arc length of the pole face of the mover. In one aspect of the invention, the stator core may further include a yoke portion extending in the vessel axial direction and having a plurality of salient pole portions formed at predetermined intervals in the vessel radial direction of the pressure vessel, and the coil may be wound around at least one salient pole portion so as to form a ring shape in the vessel radial direction. In one aspect of the present invention, the stator core may further include a yoke portion extending in the vessel axial direction and having a plurality of salient pole portions formed at predetermined intervals in the vessel radial direction of the pressure vessel, and the coil may be wound around the yoke portion so as to form a ring shape relative to the vessel axial direction. In the above-described aspect, the mover and the stator may be arranged in a partial region in the circumferential direction of the pressure vessel. [Effects of the Invention]

[0009] According to one aspect, a linear motor capable of efficiently driving a movable body within a cylindrical pressure vessel can be provided. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a schematic diagram showing the overall configuration of a pressure vessel and a linear motor. [Figure 2] FIG. 1 is a front view of a linear motor according to a first embodiment. [Figure 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] FIG. 3 is a diagram showing a modification of FIG. 2. [Figure 5] FIG. 10 is a perspective view of a linear motor according to a second embodiment. [Figure 6] FIG. 10 is a front view of a linear motor according to a second embodiment. [Figure 7] FIG. 10 is a side view of a linear motor according to a second embodiment. [Figure 8] FIG. 7 is a cross-sectional view taken along line BB in FIG. 6. [Figure 9] FIG. 10 is a diagram showing changes in electromagnetic force of the linear motor in the example and the comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the embodiments, in order to make the explanation easier to understand, the structures and elements other than the main parts of the present invention will be explained in a simplified or omitted manner. Furthermore, the same elements will be given the same reference numerals in the drawings. Note that the shapes, dimensions, etc. of the elements shown in the drawings are shown schematically and do not represent the actual shapes, dimensions, etc.

[0012] (First embodiment) Figure 1 is a schematic diagram showing the overall configuration of a pressure vessel and a linear motor. The pressure vessel 1 of this embodiment has a sealed cylindrical shape, and the interior of the pressure vessel 1 is isolated from the environment outside the vessel. The interior of the pressure vessel 1 is set under pressure conditions (e.g., a vacuum environment) different from those outside the vessel. The material of the pressure vessel 1 can be one that has sufficiently high rigidity (pressure resistance) as well as relatively low magnetic permeability and allows magnetic flux to pass through easily.

[0013] A linear motor 2 is arranged along the axial direction (left-right direction in Figure 1) of the pressure vessel 1 at a part of the circumferential direction of the pressure vessel 1. A movable body 3 and a movable element 4 of the linear motor 2 are housed inside the pressure vessel 1, and a stator 5 of the linear motor 2 is arranged outside the pressure vessel 1.

[0014] The movable body 3 is a disk-shaped body with an outer diameter smaller than the inner diameter of the pressure vessel 1, and is supported within the vessel so as to be movable in the axial direction of the vessel. A mover 4 of the linear motor 2 is connected to one surface of the movable body 3 (the surface on the left side in FIG. 1).

[0015] The mover 4 is arranged to extend in the vessel axial direction and has a magnetic pole section 7 in which permanent magnets 6 of opposite polarity (south pole permanent magnets and north pole permanent magnets) are arranged alternately in a straight line. The magnetic pole section 7 of the mover 4 faces the cylindrical inner peripheral surface of the pressure vessel 1 via a small gap.

[0016] The stator 5 is disposed on the outer periphery of the pressure vessel 1, facing the mover 4 across the bulkhead of the pressure vessel 1. The stator 5 has multiple coils (not shown in FIG. 1) arranged linearly in the vessel axial direction. In the linear motor 2, an alternating magnetic field is generated in the stator 5 by passing a current through the coils of the stator 5, which generates a magnetic attraction force or a repulsion force between the stator 5 and the permanent magnet 6 of the mover 4. This enables the linear motor 2 to drive the mover 4 and the mover 3 inside the pressure vessel 1 in the vessel axial direction.

[0017] As an example, the pressure vessel 1 and linear motor 2 described above can be applied to adjusting the position of a movable electrode within the pressure vessel 1 of a variable capacitance vacuum capacitor. In the above application, the movable electrode (not shown) of the vacuum capacitor is arranged on the other side (the right side in Figure 1) of the movable body 3 connected to the mover 4. The movable electrode is also arranged to face a fixed electrode (not shown) within the pressure vessel 1 of the vacuum capacitor. The movable electrode and fixed electrode are arranged to extend in the axial direction of the vessel with a gap in the radial direction of the vessel. By moving the movable body 3 in the axial direction of the vessel with the linear motor 2, the opposing area between the movable electrode and fixed electrode within the pressure vessel 1 changes, allowing the vacuum capacitor to obtain any desired capacitance.

[0018] Next, a configuration example of the linear motor 2 of the first embodiment will be described with reference to Figs. 2 to 4. Fig. 2 is a front view of the linear motor 2 of the first embodiment. Fig. 3 is a cross-sectional view taken along line AA in Fig. 2. Fig. 4 is a diagram showing a modified example of Fig. 2. For simplicity, the movable body 3 is not shown in Figs. 2 to 4.

[0019] The mover 4 has a flat mover yoke 8 extending in the container axial direction, and a magnetic pole section 7 consisting of a plurality of permanent magnets 6. The magnetic pole section 7 is formed by arranging permanent magnets 6 of different polarities alternately on the mover yoke 8. Note that the magnetization orientation of each permanent magnet 6 of the magnetic pole section 7 may be radial, in which case it follows the container radial direction at each position on an arc described below, or may be parallel, in which the magnetization orientation at each position on the arc is uniform.

[0020] As shown in Figure 2, the permanent magnet 6 of the mover 4 is formed so that the surface facing the pressure vessel 1 in a plane perpendicular to the vessel axial direction forms an arcuate surface concentric with the inner circumferential surface of the pressure vessel 1 and convex toward the pressure vessel 1. As a result, the magnetic pole portion 7 occupies a larger amount of magnet in the space between the mover yoke 8 and the pressure vessel 1 than when a flat magnet is placed on the mover yoke 8, and the opposing area between the magnetic pole portion 7 and the inner circumferential surface of the pressure vessel 1 is also larger. In addition, the gap between the surface of the magnetic pole portion 7 of the mover 4 and the inner circumferential surface of the pressure vessel 1 is uniform in the circumferential direction of the pressure vessel 1.

[0021] The stator 5 has a stator core 11 and a plurality of coils 12 wound around the stator core 11. In the first embodiment, the stator core 11 has a yoke portion 11a extending linearly in the axial direction of the container, and a plurality of teeth 11b extending radially from the yoke portion 11a and formed in a comb-like shape at regular intervals in the axial direction of the container. The teeth 11b are an example of salient poles of the stator core 11.

[0022] The stator 5 is arranged so that the tips of the teeth 11b face the outer peripheral surface of the pressure vessel 1. In addition, in the stator core 11, spaces (slots) for winding the coils 12 are formed between the comb-tooth-shaped teeth 11b.

[0023] The coils 12 of the stator 5 are wound around each of the teeth 11b of the stator core 11, which extend in the radial direction of the container. Each coil 12 is wound around the corresponding tooth 11b so as to form a ring in the radial direction of the container, and the winding of the coil 12 passes through two adjacent slots. One slot of the stator core 11 accommodates the windings of two adjacent coils 12. Note that an insulator (not shown) made of an insulating material such as resin is disposed between the stator core 11 and each coil 12.

[0024] 2, arc-shaped recesses 11c are formed at the tips of the teeth 11b of the stator core 11. The arcs of the recesses 11c are concentric with the outer peripheral surface of the pressure vessel 1 in a plane perpendicular to the vessel axial direction, and are concave toward the pressure vessel 1. By forming the recesses 11c at the tips of the teeth 11b, the opposing area between the tips of the teeth 11b and the outer peripheral surface of the pressure vessel 1 is larger than when the tips of the teeth 11b are flat. In addition, the gap between the tips of the teeth 11b and the outer peripheral surface of the pressure vessel 1 is uniform in the circumferential direction of the pressure vessel 1.

[0025] 2 shows an example in which the arc length of the arc surface 7a of the magnetic pole portion 7 of the mover 4 is approximately equal to the arc length of the recess 11c of the stator 5 in a plane perpendicular to the container axial direction. However, as shown in FIG. 4, in the linear motor 2, the arc length of the recess 11c of the stator 5 may be longer than the arc length of the arc surface 7a of the magnetic pole portion 7 of the mover 4.

[0026] As shown in Figure 4, when the arc length of the recess 11c of the stator 5 is made longer than the arc length of the arc surface 7a of the mover 4 in a plane perpendicular to the vessel axial direction, the flux linkage between the stator 5 and the mover 4 increases and leakage flux is suppressed compared to the case of Figure 2. Furthermore, since the weight of the mover 4 does not increase even if the dimensions of the stator 5 are increased, there is no decrease in thrust density due to the increase in the weight of the mover 4. Therefore, with the configuration of Figure 4, it is possible to further improve the electromagnetic force of the linear motor 2 that drives the mover 3 inside the pressure vessel 1.

[0027] Here, consider a case where the arc length of the recess 11c of the stator 5 and the arc length of the arc surface 7a of the mover 4 are defined using the angle at the central axis of the pressure vessel 1. In order to increase the magnetic flux linkage when the permanent magnets 6 of the magnetic pole portion 7 are parallel oriented, the arc angle of the recess 11c of the stator 5 should be equal to or greater than the arc angle of the arc surface 7a of the mover 4. On the other hand, in order to increase the magnetic flux linkage when the permanent magnets 6 of the magnetic pole portion 7 are radially oriented, it is more preferable that the arc angle of the recess 11c of the stator 5 be greater than the arc angle of the arc surface 7a of the mover 4.

[0028] As described above, the linear motor 2 of the first embodiment includes the mover 4 that is movable in the vessel axial direction within the cylindrical pressure vessel 1, and the stator 5 that is disposed outside the pressure vessel 1 and facing the mover 4 across the pressure vessel 1. The magnetic pole face (7a) of the mover 4 that faces the inner peripheral surface of the pressure vessel 1 is formed in an arc shape that is concentric with the inner peripheral surface of the pressure vessel 1 and convex toward the pressure vessel 1. This maximizes the amount of magnet in the mover 4 within the arc-shaped pressure vessel 1, increases the facing area between the magnetic pole portion 7 and the pressure vessel 1, and uniforms the circumferential gap between the magnetic pole portion 7 and the pressure vessel 1. Furthermore, the tips of the teeth 11b of the stator 5 that protrude toward the magnetic pole face have arc-shaped recesses 11c that are concentric with the outer peripheral surface of the pressure vessel 1 and concave toward the pressure vessel 1. This increases the facing area between the teeth 11b and the pressure vessel 1 and uniforms the circumferential gap between the teeth 11b and the pressure vessel 1. That is, in the first embodiment, the opposing area between the magnetic pole faces of the mover 4 and the stator 5 across the cylindrical pressure vessel 1 is sufficiently ensured, the circumferential gap between the mover 4 and the stator 5 is uniform, and the amount of magnet in the mover 4 is large, so the thrust of the mover 4 in the vessel axial direction is high. Therefore, the linear motor 2 of the first embodiment can efficiently drive the mover 3 inside the cylindrical pressure vessel 1.

[0029] In the first embodiment described above, a configuration example of concentrated winding in which the winding of the coil 1 is wound around one tooth 11b to form a ring in the radial direction of the container has been described. However, the winding of the coil 1 in the first embodiment may be distributed winding in which the winding is wound around multiple teeth 11b to form a ring in the radial direction of the container.

[0030] (Second embodiment) Next, a configuration example of a linear motor according to a second embodiment will be described with reference to Figures 5 to 8. In the following description of the second embodiment, elements common to the first embodiment will be given the same reference numerals, and duplicated description will be omitted where appropriate.

[0031] The second embodiment is a modified example of the first embodiment, and is a configuration example in which the coil 12 is wound around the stator core 11 so as to form a ring shape in the axial direction of the vessel. In the second embodiment, the configurations of the pressure vessel 1 and the mover 4 are the same as those of the first embodiment.

[0032] Fig. 5 is a perspective view of a linear motor 2A of the second embodiment. Fig. 6 is a front view of a linear motor 2A of the second embodiment. Fig. 7 is a side view of a linear motor 2A of the second embodiment. Fig. 8 is a cross-sectional view taken along line BB in Fig. 6.

[0033] The stator 5A has a stator core 11 and a plurality of coils 12 wound around the stator core 11. In the second embodiment, the stator core 11 has a yoke portion 11a that extends linearly in the axial direction of the container, and a plurality of teeth 11b that extend in the radial direction of the container, intersecting with the yoke portion 11a. The plurality of teeth 11b all have the same shape and are arranged at regular intervals in the axial direction of the container. In the stator core 11, spaces (slots) for winding the coils 12 are formed between adjacent teeth 11b and yoke portions 11a.

[0034] In the second embodiment, the coil 12 is wound around the yoke portion 11a of the stator core 11 so as to form a ring shape in the axial direction of the container. The winding of the coil 12 passes through two slots formed at the same position in the axial direction of the container, separated by the yoke portion 11a. Note that an insulator (not shown) made of an insulating material such as resin is disposed between the stator core 11 and each coil 12.

[0035] In addition, the stator 5A of the second embodiment is arranged so that the tip of one of the teeth 11b1 branching from the yoke portion 11a faces the outer circumferential surface of the pressure vessel 1. The one of the teeth 11b1 in the second embodiment is an example of a salient pole portion of the stator core 11.

[0036] An arc-shaped recess 11c is formed at the tip of one of the teeth 11b1. The arc of the recess 11c is concentric with the outer peripheral surface of the pressure vessel 1 in a plane perpendicular to the vessel axial direction and is concave toward the pressure vessel 1. By forming the recess 11c at the tip of one of the teeth 11b1, the opposing area between the tip of the tooth 11b1 and the outer peripheral surface of the pressure vessel 1 is larger than when the tip of the tooth 11b1 is flat. In addition, the gap between the tip of the tooth 11b1 and the outer peripheral surface of the pressure vessel 1 is uniform in the circumferential direction of the pressure vessel 1.

[0037] Although not particularly limited, in the second embodiment, in a plane perpendicular to the container axial direction, the arc length of the arc surface 7a of the movable member 4 and the arc length of the recess 11c of the stator 5 may be approximately equal, or the arc length of the recess 11c of the stator 5 may be longer than the arc length of the arc surface 7a of the movable member 4.

[0038] As described above, the configuration of the mover 4 of the second embodiment is the same as that of the first embodiment, and the stator 5A of the second embodiment also has, like the first embodiment, an arc-shaped recess 11c at the tip of one of the teeth 11b1 that protrudes toward the magnetic pole face, which is concentric with the outer circumferential surface of the pressure vessel 1 and recessed toward the pressure vessel 1. Therefore, like the first embodiment, the linear motor 2A of the second embodiment can also increase the thrust of the mover 4 in the vessel axial direction, and can efficiently drive the mover 3 inside the cylindrical pressure vessel 1.

[0039] Furthermore, in the linear motor 2A of the second embodiment, the coil 12 of the stator 5A is wound around the yoke portion 11a of the stator core 11 so as to form a ring shape in the axial direction of the housing. Focusing on the surface of the stator 5A facing the mover 4, in the second embodiment, the coil 12 is wound around the stator core 11, also using the space on the surface opposite to the surface facing the mover 4. This allows the same amount of coil 12 to be wound with half the slot cross-sectional area in the axial direction of the housing compared to the configuration of the first embodiment. In other words, in the configuration of the second embodiment, the coil pitch of the stator 5A in the axial direction of the housing can be reduced, and the magnetic pole pitch of the opposing mover 4 can also be reduced to match the stator, thereby reducing the size of the mover 4 in the axial direction of the housing. Furthermore, when the size of the mover 4 in the axial direction of the housing is reduced as described above, the weight of the mover 4 can be reduced by reducing the magnets and yokes, thereby further improving the thrust density of the motor.

[0040] (Example) Fig. 9 shows the change in electromagnetic force of the linear motor in the example and comparative example. Fig. 9 shows a linear motor in which a mover having a permanent magnet is driven by the magnetic field of a stator coil. The electromagnetic force of each linear motor was calculated by simulation while changing the gap surface shape, magnetization orientation of the magnet, recess dimensions, and applied voltage to the coil. In each example in Fig. 9, the stator coil is configured so that the coil is wound around the yoke in a circular shape in the axial direction of the container.

[0041] Comparative Example 1 shows an example of calculation of electromagnetic force when the gap surface shape between the stator and the mover is flat and the magnetization orientation of the permanent magnet of the mover is parallel. On the other hand, Examples 1 to 8 all show examples of calculation of electromagnetic force when the gap surface shape between the stator and the mover is arc-shaped. In Examples 1 to 4, the permanent magnet of the mover is parallel-oriented, and in Examples 5 to 8, the permanent magnet of the mover is radially oriented.

[0042] In Examples 1 and 5, the magnet width of the mover and the tooth width of the stator are both the same as the magnet width of Comparative Example 1, but when viewed in terms of the angle at the central axis of the pressure vessel, the arc angle of the teeth is set smaller than the arc angle of the magnet of the mover. In Examples 2 to 4 and Examples 6 to 8, the arc length of the teeth is set longer than the arc length of the magnet of the mover. Examples 1 and 5, Examples 2 and 6, Examples 3 and 7, and Examples 4 and 8 each have the same magnet and tooth shapes but different magnetization orientations of the permanent magnets.

[0043] In Examples 1 to 8 in Fig. 9, the gap length between the stator and the mover, magnet width, teeth width, and voltage values ​​are shown as normalized values ​​based on Comparative Example 1. Furthermore, the weight of the mover is the same in Comparative Example 1 and Examples 1 to 8 in Fig. 9, and the performance of the linear motor is evaluated by the electromagnetic force.

[0044] Comparing the configurations of Examples 1 to 8 in Figure 9 where the magnet and teeth shapes are the same (combinations of Examples 1 and 5, 2 and 6, 3 and 7, and 4 and 8), it can be seen that roughly the same electromagnetic force is obtained regardless of the magnetization orientation of the permanent magnet. Therefore, if the gap surface shape between the stator and mover is arc-shaped, various magnets can be used without being restricted by the magnet manufacturing and processing methods.

[0045] 9, when the gap surface between the stator and the mover is formed in an arc shape, the electromagnetic force of the linear motor can be increased by increasing the width of the teeth on the stator side (the arc length of the teeth). For example, as in Examples 2 and 6, by making the arc angle of the teeth equal to the arc angle of the magnet of the mover and increasing the arc length of the teeth, it is possible to obtain an electromagnetic force similar to that of Comparative Example 1.

[0046] Furthermore, since the pressure vessel has a cylindrical shape from the viewpoint of pressure resistance, if the gap surface is made flat as in Reference Example 1, the gap length will increase in the circumferential direction, and there is a possibility that the desired electromagnetic force will not be obtained when a linear motor is mounted in the pressure vessel. Therefore, when mounting a linear motor in a pressure vessel, it is preferable that the gap surface shape between the stator and the mover be an arc shape.

[0047] The present invention is not limited to the above-described embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention.

[0048] For example, in the above embodiment, a variable capacitance vacuum capacitor has been described as an example of the application of the pressure vessel and linear motor. However, the pressure vessel and linear motor of the above embodiment are not limited to the application of a variable capacitance vacuum capacitor, and may be implemented in other devices configured to move a movable body within a pressure vessel. Furthermore, the shape of the movable body and the attachment position of the mover relative to the movable body may be changed as appropriate depending on the type of device, etc.

[0049] Furthermore, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0050] 1... pressure vessel, 2, 2A... linear motor, 3... moving body, 4... mover, 5, 5A... stator, 6... permanent magnet, 7... magnetic pole portion, 7a... arc surface, 8... mover yoke, 11... stator core, 11a... yoke portion, 11b, 11b1... teeth portion, 11c... recess, 12... coil

Claims

1. A linear motor provided in a cylindrical pressure vessel for driving a movable body within the pressure vessel, a movable element disposed inside the pressure vessel, connected to the movable body, and movable in the vessel axial direction of the pressure vessel along an inner circumferential surface of the pressure vessel; a stator disposed outside the pressure vessel and facing the mover across the pressure vessel, the mover has a magnetic pole surface facing the inner circumferential surface of the pressure vessel and on which a plurality of magnets are arranged, the stator has a coil that generates a magnetic flux that drives the mover, and a stator core that includes a salient pole portion that protrudes toward the magnetic pole surface, the magnetic pole surface is formed in an arc shape that is concentric with the inner circumferential surface of the pressure vessel and that is convex toward the pressure vessel, The tip of the salient pole portion has an arc-shaped recess that is concentric with the outer circumferential surface of the pressure vessel and recessed toward the pressure vessel. Linear motor.

2. The arc length of the recess of the stator is longer than the arc length of the magnetic pole face of the mover.

2. The linear motor according to claim 1.

3. the stator core further includes a yoke portion extending in the vessel axial direction and having a plurality of the salient pole portions formed at predetermined intervals in the vessel radial direction of the pressure vessel, The coil is wound around at least one of the salient pole portions so as to form a ring shape in the radial direction of the container.

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

4. the stator core further includes a yoke portion extending in the vessel axial direction and having a plurality of the salient pole portions formed at predetermined intervals in the vessel radial direction of the pressure vessel, The coil is wound around the yoke portion so as to form a ring shape with respect to the axial direction of the container.

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

5. The mover and the stator are disposed in a partial region in the circumferential direction of the pressure vessel.

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

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