JP2018137873A - Linear motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear motor capable of reducing suction force generated between a movable element and a stator while maintaining characteristics of a linear motor with a core capable of obtaining prescribed thrust by small drive magnetomotive force.SOLUTION: A linear motor 10 combines a movable element 1 in which a drive coil 12 is wound about a movable element body 11, in whose recess arranged in upper and lower two rows of a movable element core 14 at an equal interval a permanent magnet 13 is embedded, with a stator 2 in which a plurality of magnetic pole teeth 22 are arranged at an equal interval on respective two faces of a yoke 21 facing both rows of the movable element 1. Each permanent magnet 13 is magnetized in parallel in a moving direction and the magnetization directions of adjoining permanent magnets 13, 13 in each row are opposite. The magnetization directions of the upper and lower permanent magnets 13, 13 at the same position in a movement direction are also opposite. The plurality of the upper and lower magnetic pole teeth 22 are at a same position in a direction of movement. An arrangement interval of the magnetic pole teeth 22 is as twice as that of the permanent magnets 13.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an armature movable type linear motor that extracts a linear motion output by combining a mover having a drive coil and a permanent magnet and a stator having magnetic pole teeth.

  Semiconductor and liquid crystal display manufacturing facilities require a mechanism for accurately transporting a manufacturing intermediate with low vibration in an XY plane perpendicular to the direction of gravity. The XY table is driven by an actuator that can move independently on orthogonally arranged linear guides, and the intermediate product is conveyed. Since the movement of this mechanism requires high accuracy and no vibration, a method of changing the force of a rotating machine to a parallel movement with a ball screw, which is used in general processing machines, is used. In addition, a linear motor capable of direct translation is used as a drive mechanism. As such a linear motor, a coreless linear motor in which no detent force is generated in principle is widely used to reduce the detent force (stress pulsation generated when the mover is moved without being driven). .

  A linear motor having a long permanent magnet field attached in parallel to the linear guide of the XY table is used. Specifically, the permanent magnet field is permanently arranged inside the outer yoke having a groove-shaped cross section so that the polarity periodically changes so that the armature to be driven can be easily attached to the side surface of the XY table. A three-phase drive coil is inserted in the magnetic field created by these permanent magnets, and a thrust generated in the longitudinal direction of the field is obtained by applying a three-phase alternating current synchronized with the field period. In such a structure, the drive coil does not generate stress other than the moving direction. Therefore, since there is no internal support structure and it is only necessary to be cantilever fixed to the side surface of the XY table, the support structure is simplified.

  In the coreless linear motor, the driving coil does not have an iron core and is an air-core coil, so the driving thrust is only the Lorentz force. For this reason, the thrust which generate | occur | produces with respect to a drive current is small compared with a linear motor with a core. Therefore, in order to obtain a predetermined thrust, the thrust is ensured by applying more current than the cored linear motor. Here, since the copper loss generated in the drive coil is proportional to the square of the drive current, the coreless linear motor has a problem of large heat generation. Since the drive coil generates a large amount of heat, a large liquid-cooling type cooling device is required, resulting in an increase in cost. In addition, liquid leakage may occur.

  Various types of linear motors with a core that can obtain a predetermined thrust with a small driving magnetomotive force in order to suppress the heat generation by obtaining a thrust with a Maxwell force by using a coil with a core as a driving coil have been proposed. (Patent Documents 1 to 3 etc.).

International Publication No. 2014/148434 JP 2001-157435 A International Publication No. 2014/141877

  In the linear motor disclosed in Patent Document 1, the stator has two plate-like portions that are long in the moving direction of the mover, and a plurality of magnetic pole teeth are provided on one of the opposing surfaces of the two plate-like portions. The magnetic pole teeth of the plate-like portion and the magnetic pole teeth of the other plate-like portion are juxtaposed in the moving direction, and the mover is arranged in the drive coil in two permanent directions along the moving direction. It has a configuration in which magnets and three yokes are alternately arranged, and the two permanent magnets are magnetized in parallel to the moving direction, and the magnetization directions are opposite.

  In this linear motor, the magnetic pole teeth of the stator are arranged so as to be shifted in the movement direction between the two plate-like portions, so that the direction perpendicular to the movement direction (two plate-like parts) is accompanied by the movement of the mover. Large suction force alternately occurs in the positive and negative directions. As a result, problems such as vibration of the mover and contact of the mover to the stator arise. And since a big burden is applied also to the support structure of a needle | mover, there also exists a problem that a large sized support structure is required.

  In the linear motor disclosed in Patent Document 2, a plurality of permanent magnets are arranged in a moving direction with an armature yoke interposed inside a drive coil of a mover, and the plurality of permanent magnets are magnetized in parallel to the moving direction. Therefore, the adjacent magnets have a configuration in which a mover having a magnetization direction opposite to a mover and a stator having magnetic pole teeth arranged in the moving direction are opposed to each other.

  Even in this linear motor, a large amount of magnetic flux from the permanent magnet is generated on the magnetic pole tooth side of the stator when it is not driven, so a large attractive force is generated between the stator and the mover. Since a large attractive force is generated when the position of the magnetic pole teeth coincides, a large attractive force ripple is generated as the mover moves. Therefore, a support structure having high rigidity is required to suppress this large suction force ripple.

  In the linear motor disclosed in Patent Document 3, two stators in which a plurality of permanent magnets are arranged in the moving direction are opposed to each other with an armature yoke interposed inside the drive coil, and between the two stators. The mover is inserted. In this linear motor, a large gap magnetic flux is generated between the armature yokes arranged so that the upper and lower stators are opposed to each other. The forces acting on the child are offset and become smaller.

  However, in this linear motor, when the mover is slightly displaced in the vertical direction, a large suction force acts on the narrower gap, so that the mover further moves in the same direction as the displacement. It will be. Therefore, when the rigidity of the support structure of the mover is small, there is a possibility that the mover and the stator are in contact with each other, and there is a problem that the support structure of the mover is enlarged.

  As described above, the conventional cored linear motor that obtains a predetermined thrust with a small driving magnetomotive force to suppress heat generation is fixed regardless of whether it is driven or not. Since a large suction force that does not contribute to thrust is generated between the child and the mover in a direction perpendicular to the moving direction (up and down direction), there is a problem that a large and highly rigid mover support structure is required. .

  The present invention has been made in view of such circumstances, and while maintaining the characteristics of a cored linear motor capable of obtaining a predetermined thrust with a small driving magnetomotive force, between the mover and the stator. It is an object of the present invention to provide a linear motor that can reduce the suction force ripple in the direction (vertical direction) perpendicular to the moving direction of the mover because the generated suction force is small and can reduce the size of the support structure of the mover. .

  The linear motor according to the present invention is an armature movable linear motor that extracts a linear motion output by combining a mover having a drive coil and a permanent magnet and a stator having magnetic pole teeth. A configuration in which a drive coil is wound around a mover body having a mover core made of a soft magnetic material, each having a plurality of recesses formed at equal intervals in the moving direction, and a permanent magnet fitted in each of the plurality of recesses. The positions of the concave portions in one row and the concave portions in the other row are the same in the moving direction, and the magnetization direction of the permanent magnet is parallel to the moving direction, and the permanent magnets adjacent to each other in each row The magnetization directions of the magnets are opposite to each other, and the magnetization directions of the permanent magnets in both rows at the same position in the moving direction are also opposite to each other, and the stator is arranged in both rows of the movers. Each of the two surfaces has two surfaces facing each of the permanent magnets, and each of the two surfaces is provided with a plurality of magnetic pole teeth at equal intervals in the moving direction. The position of the surface of the magnetic pole teeth with the magnetic pole teeth is the same in the movement direction, and the interval between the magnetic pole teeth adjacent in the movement direction is twice the interval between the permanent magnets adjacent in the movement direction. .

  In the linear motor of the present invention, a drive coil is wound around a mover main body having a configuration in which permanent magnets are embedded in a plurality of concave portions arranged at equal intervals in the upper and lower two rows in the moving direction. And a stator in which a plurality of magnetic pole teeth are arranged at equal intervals in the moving direction on each of two surfaces facing both rows of the movers. The position in the moving direction of the concave portion (permanent magnet) in one row is the same as the position in the moving direction of the concave portion (permanent magnet) in the other row. All permanent magnets are magnetized parallel to the moving direction, but the adjacent permanent magnets in each row have opposite magnetization directions, and the upper and lower permanent magnets at the same position in the moving direction also have opposite magnetization directions. The direction. The position of the upper magnetic pole teeth in the moving direction is the same as the position of the lower magnetic pole teeth in the moving direction. The arrangement interval of the magnetic pole teeth in the moving direction in the stator is twice the arrangement interval of the permanent magnets in the moving direction in the mover.

  Since the magnetization directions of the upper and lower permanent magnets are opposite to each other, a magnetic flux is generated so as to close in the mover core when the drive coil is not energized, so the magnetic flux density generated between the mover and the stator is small, The force with which the mover attracts the magnetic pole teeth of the stator is very small. In addition, when the drive coil is energized, the upper and lower magnetic pole teeth of the stator are provided at the same position in the moving direction, so that they are simultaneously attracted in the opposite directions in the upper and lower directions, and the vertical attractive force is canceled out. The Therefore, also at this time, the force for attracting the magnetic pole teeth of the stator is small. Therefore, since the suction force is small, the structure for supporting the mover is small and it is not necessary to use a structure having high rigidity.

  The linear motor according to the present invention is characterized in that the number of the permanent magnets in each of the two rows is an odd number.

  In the linear motor of the present invention, an odd number of permanent magnets are provided in the upper and lower rows. In this way, when the number of permanent magnets is an odd number, for example, when the electrical angle is 90 ° and the electrical angle is 270 ° at which the maximum thrust is obtained, the same number of locations where the magnetic flux flows between the magnetic pole teeth. Therefore, thrust ripple does not occur during one cycle, and smooth movement is realized.

  In the linear motor according to the present invention, the stator is a stator having a U-shaped cross section and one end being open, and having two surfaces parallel to the moving direction and facing the mover. Features.

  In the linear motor according to the present invention, the configuration of the stator is simplified by using a stator having one end having a U-shaped cross section and having two surfaces parallel to the moving direction and facing the mover. Become. In addition to reducing the suction force ripple in the direction perpendicular to the moving direction of the mover (vertical direction) because the suction force generated between the mover and the stator is small, the mover and the stator are combined. The overall size of the linear motor can be reduced.

  In the linear motor of the present invention, the thrust is obtained by the Maxwell force by using the coil with the core as the drive coil, so that a predetermined thrust is obtained with a smaller drive magnetomotive force than the coreless type linear motor. be able to. In addition, since the applied current is small, the amount of heat generation can be suppressed, and a large cooling facility such as a coreless linear motor is not required. On the other hand, the linear motor of the present invention reduces the magnetic flux density generated between the mover and the stator when not driven, and generates a lot of magnetic flux that generates thrust when driven. The suction force between the mover and the stator can be reduced, and a large support structure is not required to support the mover. Therefore, in the linear motor of the present invention, significant downsizing and cost reduction can be realized.

It is a perspective view which shows the structure of the linear motor of this invention. It is a partially broken perspective view from the AA 'line of FIG. 1 which shows the structure of the needle | mover in the linear motor of this invention. It is a perspective view which shows the structure of the needle | mover main body in the linear motor of this invention. It is a perspective view which shows the structure of the stator in the linear motor of this invention. It is a figure which shows the flow of the magnetic flux in the linear motor (electric angle 0 degree of a drive magnetomotive force) of this invention. It is a figure which shows the flow of the magnetic flux in the linear motor (electrical angle of drive magnetomotive force 90 degrees) of this invention. It is a figure which shows the flow of the magnetic flux in the linear motor (electrical angle of drive magnetomotive force 270 degrees) of this invention. It is a figure which shows the magnetic flux generation model of the linear motor disclosed by patent document 1. FIG. It is a figure which shows the magnetic flux generation model of the linear motor of this invention. It is a top view which shows the raw material used for preparation of a needle | mover core. It is a longitudinal cross-sectional view which shows the structure of the produced linear motor. It is a cross-sectional view which shows the structure of the produced linear motor. It is a graph which shows the measurement result of the thrust generate | occur | produced with respect to the drive magnetomotive force of a linear motor. It is a graph which shows the measurement result of the thrust fluctuation | variation with respect to the electrical angle of the single phase linear motor of this invention, and a suction | attraction force fluctuation | variation. It is the top view and side view which show the structure of the linear motor (1st comparative example) disclosed by patent document 1. FIG. It is a top view, a top view, and a side view showing the configuration of a conventional coreless linear motor (second comparative example). It is a graph which shows the measurement result of the thrust generated to the drive magnetomotive force of the 1st comparative example. It is a graph which shows the measurement result of the thrust fluctuation | variation with respect to the electrical angle of the single phase linear motor of a 1st comparative example, and attraction force fluctuation | variation. It is a graph which shows the measurement result of the thrust and copper loss which generate | occur | produced with respect to the drive magnetomotive force of the 2nd comparative example. It is a graph which shows the maximum thrust in this invention example, a 1st comparative example, and a 2nd comparative example. It is a graph which shows the attraction | suction force in the direction perpendicular | vertical to the moving direction in this invention example, a 1st comparative example, and a 2nd comparative example. It is a graph which shows the copper loss at the time of thrust 300N generation | occurrence | production in the example of this invention, a 1st comparative example, and a 2nd comparative example.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof. In addition, in the dimensions, when height, length, and width are described in particular, the height is a plan view, the vertical dimension in the BB 'cross-sectional view or the side view, and the length is the left and right in the plan view. The dimension and width in the direction indicate the dimension in the left-right direction in the BB ′ sectional view or side view.

  FIG. 1 is a perspective view showing the configuration of the linear motor of the present invention. 2, 3, and 4 respectively show a partially broken perspective view from the line AA ′ of FIG. 1 showing the configuration of the mover in the linear motor of the present invention, and the configuration of the mover main body. It is a perspective view which shows a perspective view and the structure of a stator. In FIGS. 1 and 3, the solid-line arrows represent the moving direction of the mover (hereinafter also simply referred to as “moving direction”).

  A linear motor 10 of the present invention is configured by combining a mover 1 having a drive coil 12 and a plurality of permanent magnets 13 and a stator 2 having a plurality of magnetic pole teeth 22, and linearly moves in the direction of a solid arrow. This is an armature-movable linear motor that extracts output. First, the structure of the needle | mover 1 is demonstrated.

  The mover 1 has a configuration in which a drive coil 12 is wound around a mover body 11 (see FIG. 2). In FIG. 2, illustration of a part (front side) of the drive coil 12 is omitted so that the internal configuration of the movable body 11 can be easily understood. The mover body 11 has a configuration in which a plurality of permanent magnets 13 and a mover core 14 made of a soft magnetic material that holds the permanent magnets 13 are integrated (see FIG. 3).

  A plurality of (seven in this example) rectangular recesses 14a are formed in the mover core 14 at equal intervals in the moving direction over two upper and lower rows. The shapes of these recesses 14a are all the same, and the positions of the recesses 14a in the upper row and the recesses 14a in the lower row are the same in the movement direction. The plurality of permanent magnets 13 and the mover core 14 are integrated in such a manner that one permanent magnet 13 is fitted in each of the recesses 14a. The plural (14) permanent magnets 13 forming a rectangular shape to be used have the same shape. The number of permanent magnets 13 arranged in each row is preferably an odd number as in this example (seven). The reason for the preference will be described later.

  As a result, a plurality of (seven) permanent magnets 13 with soft magnetic bodies interposed between adjacent permanent magnets 13 and 13 are arranged at equal pitches (P1 in FIG. 3) along the moving direction. It is the composition made to do. Here, P1 is the period of the permanent magnets 13 arranged. The positions in the movement direction of the plurality (seven) permanent magnets 13 in the upper magnet arrangement are the same as the positions in the movement direction of the plurality (seven) permanent magnets 13 in the lower magnet arrangement.

  In FIG. 3, the white arrow represents the magnetization direction of each permanent magnet 13. Each permanent magnet 13 is magnetized in the moving direction, but in each of the upper and lower rows, the adjacent permanent magnets 13 and 13 are magnetized in opposite directions. In addition, the magnetization directions of the upper row permanent magnets 13 and the lower row permanent magnets 13 at the same position in the moving direction are opposite to each other.

  The drive coil 12 is arranged in such a manner that the mover body 11 is wound around the outer periphery of the mover body 11 formed by integrating the plurality of permanent magnets 13 and the mover core 14 as described above. When the drive coil 12 is energized, a drive magnetomotive force is applied to the mover main body 11 in the up-down direction (opposite direction of magnetic pole teeth 22 of the stator 2 described later).

  Next, the configuration of the stator 2 will be described. The stator 2 includes a soft magnetic yoke 21 having a U-shaped cross-section and an open end. The yoke 21 is parallel to the moving direction and faces the upper and lower surfaces of the mover 1, respectively. It has two surfaces 21a and 21b (see FIG. 4). A plurality (eight in this example) of rectangular magnetic pole teeth 22 are provided on the two surfaces 21a and 21b at an equal pitch in the moving direction. All of the plural (16) magnetic pole teeth 22 forming the arranged rectangular shape have the same shape. Further, the position in the movement direction of the plurality (eight) magnetic pole teeth 22 on the upper surface 21a is the same as the position in the movement direction of the plurality (eight) magnetic pole teeth 22 on the lower surface 21b. .

  The arrangement pitch (P2 in FIG. 4) of the magnetic pole teeth 22 is twice the arrangement pitch (P1) of the permanent magnets 13 in the mover 1. Here, P2 is the period of the magnetic pole teeth 22 arranged. In one example, P1 = 7.5 mm and P2 = 15 mm as will be described later.

  In the stator 2 as described above, the mover 1 is inserted at a predetermined distance (for example, 1 mm) from the upper and lower rows of magnetic pole teeth 22 to constitute the single-phase drive linear motor 10. In addition, if the three movers 1 are arranged in the stator 2 at positions shifted from each other by 120 ° in electrical angle, a three-phase drive linear motor 10 is configured.

  Next, the flow of magnetic flux in the linear motor 10 of the present invention will be described with reference to FIGS. FIG. 5 shows the flow of magnetic flux when no drive magnetomotive force is applied (electrical angle 0 °), and FIGS. 6 and 7 show the case where the drive magnetomotive force is applied (FIG. 6: electrical angle 90 °, FIG. 7: electric). This represents the flow of magnetic flux at an angle of 270 °. 5-7, the same number is attached | subjected to the same member as FIGS. 1-4. The yoke 21 of the stator 2 is not shown because only what is necessary to explain the flow of magnetic flux is shown. Broken line arrows and thin line arrows represent the flow of magnetic flux, thick line arrows represent the direction of magnetomotive force due to current, and hatched arrows represent thrust. In FIGS. 6 and 7, ● and x indicate the direction of energization of the drive coil, ● indicates energization from the back of the paper surface to the front, and x indicates energization from the front to the back of the paper surface. 5-7, the number of permanent magnets 13 in each of the upper and lower rows is five.

  When the driving magnetomotive force is not applied, the permanent magnet 13 embedded in the mover core 14 is magnetized in opposite directions on the surface facing the stator 2 as shown in FIG. A magnetic flux as indicated by a broken line arrow is generated inside the core 14 (yoke). Since the permanent magnets 13 are arranged at the same position in the moving direction in the upper and lower directions, a magnetic flux is generated so as to be closed by the pair of upper and lower permanent magnets 13 and 13. Therefore, the flow of magnetic flux is closed inside the mover core 14, and the magnetic flux generated outside the mover 1 becomes extremely small. Therefore, the force for attracting the magnetic pole teeth 22 is very small as compared with the conventional core type linear motor.

  When a driving magnetomotive force is applied (electrical angle 90 °), as shown by a solid arrow between the magnetic pole teeth 22 from a position that does not obstruct the flow of magnetic flux generated from the permanent magnet 13 as shown in FIG. Magnetic flux is generated. The position where this magnetic flux is generated is every other mover yoke on the surface facing the stator 2, and a reverse magnetic flux is generated at the same position at the top and bottom of FIG. And since the magnetic pole teeth 22 are provided at the same position in the movement direction in the vertical direction of the figure, unlike the linear motor of Patent Document 1 in which an attractive force is alternately generated between the upper and lower sides, the magnetic pole teeth 22 are simultaneously attracted vertically. The suction force in the vertical direction is canceled out, and a stress only in the moving direction is generated. This stress becomes the thrust of the mover 1. For this reason, like the coreless type linear motor, the mover 1 can be moved silently.

  Even when the driving magnetomotive force is applied by advancing the electrical angle by 180 ° from the case of FIG. 6 (electrical angle 270 °), the flow of magnetic flux generated from the permanent magnet 13 is not hindered as shown in FIG. A magnetic flux as indicated by a solid line arrow is generated between the position and the magnetic pole teeth 22. At this time, a magnetic flux is generated in the mover yoke adjacent to the mover yoke where the magnetic flux was generated in the case of FIG. 6 (electrical angle 90 °). As in the case of FIG. 6, the suction force in the vertical direction cancels out, so that stress (thrust) only in the moving direction is generated.

  From the above, by applying an alternating current synchronized with the position of the magnetic pole teeth 22 of the stator 2 to the drive coil 12, a continuous thrust in the moving direction can be obtained, and the mover 1 can be moved smoothly. realizable.

  Here, the number of the permanent magnets 13 arranged may be either an even number or an odd number, but when arranging the odd number of permanent magnets 13, the electrical angle is 90 ° and the electrical angle is 270 °. Thus, the number of locations where the magnetic flux flows between the magnetic pole teeth 22 is the same (3 locations in the examples of FIGS. 6 and 7). Therefore, thrust ripple does not occur during one cycle. More preferably, the number of permanent magnets 13 arranged in each row is an odd number such as five or seven.

  As described above, in the linear motor 10 of the present invention, when the driving magnetomotive force is not applied, the magnetic flux generated in the gap with the stator 2 is small, so the detent force and the attractive force between the mover 1 and the stator 2 are reduced. Is small. Therefore, like the coreless linear motor, the support structure of the mover 1 may be small. Further, since the generation of suction force in the direction perpendicular to the movement direction is small during driving, quiet movement is possible. Moreover, since it is a structure with a core, compared with a coreless type | mold linear motor, calorific value is reduced significantly, and a large-sized cooling facility is unnecessary.

  A magnetic flux generation model between the mover and the stator was obtained for the linear motor disclosed in Patent Document 1 and the linear motor of the present invention. For comparison, the sizes of the stator, the movable body, and the drive coil are the same. In addition, in order to obtain | require the attraction | suction force between a needle | mover and a stator, the structure without the magnetic pole tooth of a stator was made into the object of a measurement. Hereinafter, the obtained magnetic flux generation model will be described.

  FIG. 8 is a diagram showing a magnetic flux generation model of the linear motor disclosed in Patent Document 1. FIG. 8A is a magnetic flux density distribution when no driving magnetomotive force is applied, and FIG. 8B is a driving magnetomotive force in one direction ( FIG. 8C shows the magnetic flux density distribution when the driving magnetomotive force (−1200 A) is applied in the direction opposite to that in FIG. 8B. 8A to 8C, thin line arrows indicate the flow of magnetic flux, and thick line arrows indicate the direction of magnetomotive force. As the magnetic flux density in the gap between the mover 61 and the stator 42 increases, the attractive force also increases.

  The linear motor disclosed in Patent Document 1 includes a mover 61 in which a drive coil 53 is wound around an arrangement in which permanent magnets 51 and yokes 52 are alternately arranged between two opposing surfaces of a stator 42. Make the inserted configuration. The permanent magnets 51 are both magnetized in the moving direction, but the adjacent permanent magnets 51 and 51 have opposite magnetization directions. Each permanent magnet 51 has a length of 4 mm, and the outer shape of the armature (an array of permanent magnets 51 and a yoke 52) is 12 mm high × 24 mm long × 20 mm wide, between the mover 61 and the stator 42. The gap is 2 mm above and below.

  As shown in FIG. 8A, it can be seen that a large amount of magnetic flux is generated between the mover 61 and the stator 42 even when not being driven. At this time, the suction force between the mover 61 (yoke 52) and the stator 42 was calculated to be 53 N on one side. Further, as shown in FIGS. 8B and 8C, the suction force when driven was calculated to be 73.3 N for one side. Here, the one side portion refers to one side portion of the suction force between the opposing surfaces of the mover and the stator.

  FIG. 9 is a diagram showing a magnetic flux generation model of the linear motor of the present invention. FIG. 9A is a magnetic flux density distribution when no driving magnetomotive force is applied, and FIG. 9B is a driving magnetomotive force (1200 A) applied in one direction. FIG. 9C shows the magnetic flux density distribution when the driving magnetomotive force (−1200 A) is applied in the direction opposite to that in FIG. 9B. 9A-C, thin line arrows indicate the flow of magnetic flux, and thick line arrows indicate the direction of magnetomotive force.

  The target linear motor of the present invention has a configuration in which three permanent magnets 13 are arranged one above the other. Each permanent magnet 13 has a height of 4 mm and a length of 4 mm, and the outer shape of the armature (mover body 11) is the same as that of the linear motor disclosed in Patent Document 1, and is 12 mm high × 24 mm long × width wide. 20 mm. Further, the gap between the mover 1 and the stator 2 is also 2 mm above and below, which is the same as the linear motor disclosed in the above-mentioned Patent Document 1.

  As shown in FIG. 9A, since the flow of magnetic flux is generated so as to be closed in the armature core 14 when not driven, almost no magnetic flux is generated between the mover 1 and the stator 2. I understand. For this reason, in the state which is not driven, there exists the characteristic that the attraction | suction force which acts between the needle | mover 1 and the stator 2 becomes small. The suction force when not driven was 0.8 N for one side by calculation. Further, as shown in FIGS. 9B and 9C, even in the driving state, the magnetic flux density in the gap when not driving is small, so even if the magnetic flux increases by driving, the attractive force is applied to the linear motor disclosed in Patent Document 1. It is small compared. The suction force at the time of driving was 11.8 N for one side by calculation.

  As described above, in the linear motor structure of the present invention, it has been found that the suction force between the mover (armature) and the stator can be reduced. Therefore, like the coreless linear motor, the mechanical holding structure of the mover can be simplified and reduced in size.

  Hereinafter, a specific configuration of the linear motor 10 manufactured by the present inventor and characteristics of the manufactured linear motor 10 will be described.

  First, the mover main body 11 (armature) was produced. FIG. 10 is a plan view showing a material used for manufacturing the mover core 14. 80 pieces of material 31 made of a silicon steel plate having a height of 0.5 mm and having a shape as shown in FIG. 10 were cut by wire cutting. The cut out materials 31 are overlapped and laser welded at the ends to form an outer shape of 17 mm in height, 52.5 mm in length and 40 mm in width as shown in FIG. The movable member core 14 having the concave portion 14a was obtained.

Next, 14 bar-shaped magnets having a height of 7.5 mm, a length of 4.5 mm, and a width of 40 mm from the block material of the Nd—Fe—B rare earth magnet (B _r = 1.395 T, H _cj = 1273 kA / m) were used. Cut out. The cut bar-shaped magnet was magnetized in the length direction (direction parallel to the moving direction). The magnet after magnetization was embedded as a permanent magnet 13 in the recess 14a of the mover core 14 produced as described above. At this time, the magnetization direction of the permanent magnets 13 is such that the magnetization directions of the permanent magnets 13 and 13 adjacent to each other in the movement direction are opposite to each other, and the magnetizations of the upper and lower permanent magnets 13 and 13 at the same position in the movement direction. Fourteen permanent magnets 13 were inserted so that the directions were opposite to each other. The arrangement period (P1) of the permanent magnets 13 in the upper and lower rows was 7.5 mm.

  Finally, on the outside of the mover main body 11 (armature) manufactured as described above, a 1.5 mm diameter enamel-coated conductor is placed on a plastic strand bobbin (not shown) having a strand cross section of 18 mm × 16 mm. Was driven 100 times to form a drive coil 12, and a single-phase mover 1 as shown in FIG. 2 was produced.

  Next, the stator 2 was produced. A 6 mm thick mild steel (SS400 material) plate was formed into a U-shape as the yoke 21 of the stator 2. Twelve sheets with a length of 6 mm and a width of 40 mm were cut out from a silicon steel plate with a height of 0.5 mm by wire cutting, and the cut out material was laminated and adhered in a direction perpendicular to the moving direction (height direction). Sixteen such laminates were produced, and eight magnetic pole teeth 22 were bonded to the upper and lower surfaces 21a and 21b of the yoke 21 of the stator 2 at equal intervals (see FIG. 4). The positions of the magnetic pole teeth 22 in the upper and lower rows are the same in the moving direction. In addition, the arrangement period (P2) of the magnetic pole teeth 22 on each of the upper and lower surfaces was 15 mm, which is twice the arrangement period (P1 = 7.5 mm) of the permanent magnet 13.

  The produced mover 1 is inserted into the produced stator 2 through a linear guide (not shown) so that the mover 1 can move freely in the moving direction, and the gap between the stator 2 and the magnetic pole teeth 22 rises and falls. The linear motor 10 for a single phase was obtained by fixing each to 1 mm. The linear guide was attached to the thrust test bench via a load cell so that the suction force of the mover 1 acting perpendicularly to the moving direction at the time of thrust measurement could also be measured. FIG. 11 and FIG. 12 are a longitudinal sectional view and a transverse sectional view showing the configuration of the produced linear motor 10. 11 is the same as the sectional view taken along the line AA ′ of FIG. 1, and the transverse sectional view of FIG. 12 is the same as the sectional view taken along the line BB ′ of FIG. This is what we saw from here. Further, FIG. 11 and FIG. 12 show the dimensions of each part, and the unit of numerical values of the dimensions is mm.

  Such characteristics of the linear motor 10 of the present invention were measured. Three prepared movers 1 (armature units) shown in FIG. 2 are prepared, arranged at positions deviated from each other by 120 ° in electrical angle, fixed to a linear guide, and inside the prepared stator 2 shown in FIG. Inserted into. At this time, the gap between the mover 1 and the magnetic pole teeth 22 of the stator 2 was 1 mm above and below, respectively. Then, the drive coils are star-connected, the ends of the coils are connected to the U phase, V phase, and W phase of the power source of the linear motor driver, and a three-phase drive current synchronized with the position of the mover 1 is applied. Thrust was measured. Further, the suction force of the mover 1 was also measured at the time of measuring the thrust.

  FIG. 13 is a graph showing measurement results of thrust generated with respect to the driving magnetomotive force of the linear motor 10 of the present invention. In FIG. 13, the horizontal axis represents the drive magnetomotive force (drive current of the drive coil × number of turns) [A], and the vertical axis represents the thrust [N] and the thrust magnetomotive force ratio [N / A]. In the figure, a represents the thrust, and b in the figure represents the measurement result of the thrust magnetomotive force ratio. The thrust is a three-phase composite thrust.

As shown in FIG. 13, a thrust characteristic linear with respect to the driving magnetomotive force is obtained. Further, the proportional limit at which the thrust magnetomotive force ratio is reduced by, for example, 10% does not appear clearly, and can be estimated to be 450 N or more. Further, the peak value of the driving magnetomotive force when the thrust force is 300 N is 2200 A, and the effective value of the driving current is 15.56 A, so the copper loss is (15.56 A) ² × 0.2635Ω × 3 = 192 W. It was.

  FIG. 14 is a graph showing measurement results of thrust fluctuation and suction force fluctuation with respect to the electrical angle of the single-phase linear motor 10 of the present invention. In FIG. 14, the horizontal axis represents an electrical angle [°], and the vertical axis represents thrust and suction force [N]. In addition, a and b in the figure represent measurement results of thrust and attractive force for a single-phase unit when the driving magnetomotive force 1200A is applied, respectively. The suction force is a suction force in the vertical direction of the mover 1 (direction facing the stator 2 perpendicular to the moving direction).

  As shown in FIG. 14, a sinusoidal profile in which the single-phase thrust was maximized in the vicinity of 90 ° and 270 ° at which the drive current was maximized over an electrical angle of 0 ° to 360 ° was obtained. On the other hand, it has been found that the vertical suction force of the mover 1 is almost zero, and that the stress fluctuation in the vertical direction hardly occurs like the coreless linear motor.

  In order to compare characteristics with the linear motor 10 of the present invention (hereinafter also simply referred to as the present invention example), the linear motor disclosed in Patent Document 1 (hereinafter also simply referred to as the first comparative example), and Conventional coreless linear motors (hereinafter also simply referred to as second comparative examples) as described in JP-A No. 1275759 and JP-A No. 2001-197718 were prepared, and their characteristics were measured.

  FIG. 15 is a plan view and a side view showing the configuration of the linear motor (first comparative example) disclosed in Patent Document 1. A stator 42 that is arranged in parallel in the movement direction so that the magnetic pole teeth 43 are staggered on the inner peripheral surfaces of the two plate-like parts that are vertically opposed to each other, and a permanent magnet 51 and a yoke that are magnetized parallel to the movement direction The first comparative example has a mover 61 having a configuration in which the drive coils 53 are wound by alternately arranging 52. Note that FIG. 15 shows the dimensions of each part, and the unit of numerical values of the dimensions is mm.

  FIG. 16 is a top view, a plan view, and a side view showing a configuration of a conventional coreless linear motor (second comparative example). A stator composed of a field yoke 71 and a plurality of permanent magnets 72 magnetized in parallel in the vertical direction are arranged at equal intervals in the moving direction over two upper and lower rows, and a three-phase coil 73 is placed between the upper and lower magnet rows. , 73, 73, the second comparative example has a mover made of an armature having a configuration provided. FIG. 16 shows the dimensions of each part, and the unit of the numerical value of the dimension is mm.

  In order to compare with the example of the present invention, in the first comparative example, the same material as the above-described example of the present invention was used for the permanent magnet, the armature core, the drive coil, the stator yoke, and the magnetic pole teeth. For comparison with the same physique, the shape of the stator yoke was 69 mm × 41 mm in cross section, which is the same shape as the example of the present invention (see FIG. 12) (see FIG. 15). Three phases were prepared in the same procedure as the example of the present invention, fixed to a thrust test bench, and the characteristics were measured.

  FIG. 17 is a graph showing measurement results of thrust generated with respect to the drive magnetomotive force of the first comparative example. In FIG. 17, the horizontal axis represents the drive magnetomotive force [A], and the vertical axis represents the thrust [N] and the thrust magnetomotive force ratio [N / A]. In the figure, a represents the thrust, and b in the figure represents the measurement result of the thrust magnetomotive force ratio. The thrust is a three-phase composite thrust.

As shown in FIG. 17, the proportional limit at which the thrust magnetomotive force ratio decreases by 5% is 287 N, and it was possible to generate a thrust almost equal to that of the coreless linear motor. Further, the peak value of the driving magnetomotive force when the thrust force is 300 N is 1700 A, and the effective value of the driving current is 12.02 A. Therefore, the copper loss is (12.02 A) ² × 0.634Ω × 3 = 275 W It became.

  FIG. 18 is a graph illustrating measurement results of thrust fluctuation and suction force fluctuation with respect to the electrical angle of the single-phase linear motor of the first comparative example. In FIG. 18, the horizontal axis represents an electrical angle [°], and the vertical axis represents thrust and suction force [N]. In addition, a and b in the figure represent measurement results of thrust and attractive force for a single-phase unit when the driving magnetomotive force 1200A is applied, respectively.

  As shown in FIG. 18, a thrust profile almost similar to that of the example of the present invention was obtained over one period (electrical angle 0 ° to 360 °). However, the suction force of the mover is -55N on the lower side at the 0 ° (or 360 °) position, and + 55N on the upper side at the 180 ° position. It was found that a large suction force was generated. For this reason, in the first comparative example, as the support structure of the mover, the slide is held while being firmly held so that the gap between the mover and the stator is not changed by the stress change in the direction perpendicular to the moving direction. A mechanism to do this is required. In addition, the amount of heat generated by copper loss when thrust 300 N was generated was 274.56 W, which is 43% higher than that of the example of the present invention.

  In order to compare with the example of the present invention, in the second comparative example, the same material as the above-described example of the present invention was used for the permanent magnet, the drive coil, and the stator yoke. For comparison with the same physique, the shape of the stator yoke was the same as that of the example of the present invention (see FIG. 12), and the cross section was 69 mm × 41 mm (see FIG. 16). The sample was prepared in the same procedure as the example of the present invention, fixed to a thrust test bench, and the characteristics were measured.

  FIG. 19 is a graph showing measurement results of thrust and copper loss generated with respect to the driving magnetomotive force of the second comparative example. In FIG. 19, the horizontal axis represents the driving magnetomotive force [A], and the vertical axis represents the thrust [N], the thrust magnetomotive force ratio [N / A], and the copper loss [W]. In the figure, a represents the thrust, b in the figure represents the copper loss, and c in the figure represents the measurement result of the thrust magnetomotive force ratio.

Since the second comparative example is a coreless type linear motor, as shown in FIG. 19, there is no clear drop in the thrust proportional limit, that is, the thrust magnetomotive force ratio is significantly reduced. It is estimated that the thrust that can be operated continuously is 90 N, and the maximum thrust that does not cause coil burning is about 300 N. Further, the copper loss when the thrust of 300 N was generated in the second comparative example was (7.07A) ² × 2.403Ω × 3 = 360.45W because the effective value of the drive current was 7.07A. This calorific value is 1.88 times that of the above-described example of the present invention.

  Comparison of various characteristics with the same physique in the above-described invention examples, the first comparative example, and the second comparative example will be described.

  FIG. 20 is a graph showing the maximum thrust in the present invention example, the first comparative example, and the second comparative example. In the second comparative example, which is an example of the present invention and a coreless linear motor, since there is no thrust proportional limit, the maximum thrust was obtained from the maximum current that can safely energize the drive coil. As shown in FIG. 20, it can be seen that the present invention can obtain the largest thrust with the same physique. Since the second comparative example has a high copper loss and a large amount of heat generation, it is necessary to control to the rated thrust (90 N) when continuously used. In the present invention example and the first comparative example, it is not necessary to consider the rated thrust.

  FIG. 21 is a graph showing the suction force in the direction perpendicular to the moving direction in the present invention example, the first comparative example, and the second comparative example. The second comparative example, which is a coreless type linear motor, has a structure in which an attractive force is not generated between the stator and the stator because the thrust is obtained by the Lorentz force. In the first comparative example, the moving element generates a suction force of 55 N in the direction toward the stator, that is, the force by which the entire moving element is sucked by the stator, that is, the suction force of the entire moving element with respect to the stator. Since the suction force is generated alternately up and down with the movement of the mover, a large suction force is generated. Therefore, it can be seen that a load is imposed on the support structure of the mover. On the other hand, in the example of the present invention, the force that the entire mover is attracted to the stator, that is, the suction force of the entire mover with respect to the stator is 2. Only a very small suction force of 7N is generated. Therefore, in the example of the present invention, it can be seen that the linear motor can be configured with a small support structure similar to that of the coreless linear motor.

  FIG. 22 is a graph showing the copper loss when the thrust 300N is generated in the present invention example, the first comparative example, and the second comparative example. The calorific value of the second comparative example is the largest at 360.45 W, and decreases in the order of the first comparative example (274.45 W) and the inventive example (192 W). In the example of the present invention, it can be seen that the same thrust can be generated with a heat generation amount about half that of the second comparative example (coreless linear motor).

  In addition, although the structure of the stator which has comprised the U-shaped cross section was disclosed in the Example, it is not limited to this. The U-shaped cross section may have a configuration in which the upper plate-like portion and the lower plate-like portion are partly connected by a yoke. Moreover, the structure by which the needle | mover is accommodated in the inside of the stator which has comprised the cross-sectional square shape may be sufficient.

  Moreover, although the example which has the stator of this invention in the upper and lower sides of a needle | mover was disclosed in the Example, it is not limited to this. The stator of the present invention only needs to have two surfaces facing the permanent magnets in both rows of the movers, and the same effect is obtained even when the mover is on the left or right or diagonally.

  The disclosed embodiments should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

Reference Signs List 1 mover 2 stator 10 linear motor 11 mover body 12 drive coil 13 permanent magnet 14 mover core 14a recess 21 yoke 22 magnetic pole teeth

Claims (3)

In an armature movable linear motor that extracts a linear motion output by combining a mover having a drive coil and a permanent magnet and a stator having magnetic pole teeth,
The mover includes a mover core made of a soft magnetic material having a plurality of recesses formed at equal intervals in the moving direction in each of two rows, and a mover body having a permanent magnet fitted in each of the plurality of recesses. The drive coil is wound around, the positions of the concave portions in one row and the concave portions in the other row are the same in the moving direction, and the magnetization direction of the permanent magnet is parallel to the moving direction, The magnetization directions of the adjacent permanent magnets are opposite to each other, and the magnetization directions of the permanent magnets in both rows at the same position in the moving direction are also opposite to each other.
The stator has two surfaces facing the permanent magnets in both rows of the mover, and a plurality of magnetic pole teeth are provided at equal intervals over the moving direction on each of the two surfaces, The positions of the magnetic pole teeth on one surface and the magnetic pole teeth on the other surface are the same in the moving direction,
The linear motor characterized in that an interval between the magnetic pole teeth adjacent to each other in the moving direction is twice as large as an interval between the permanent magnets adjacent to each other in the moving direction.   The linear motor according to claim 1, wherein the number of the permanent magnets in each of the two rows is an odd number.   3. The stator according to claim 1, wherein the stator has a U-shaped cross section and is open at one end, and has two surfaces parallel to a moving direction and facing the mover. The linear motor described in 1.

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