JP5452299B2 - Linear motor and its armature structure - Google Patents

Description

The present invention relates to a linear motor and an armature structure thereof, and more particularly to a linear motor capable of generating a large thrust while having low thrust pulsation and low detent thrust suitable for use in servo control. The present invention mainly provides a drive motor for generating a high output and a large thrust to realize a high acceleration operation required for an injection shaft of an injection molding machine, a pressurization ram (main shaft) of a press machine, and the like. It is intended.

  A linear motor is a stator in which a coil is formed by winding an electric wire around a core made by laminating electromagnetic steel sheets of a predetermined design shape, and a permanent magnet is inserted and fixed in a magnet insertion space provided in a structural component. The mover is combined with the mover, or the mover coil is formed by winding an electric wire around the core in the opposite manner, and the permanent magnet is inserted and fixed in the magnet insertion space provided in the structural part. Composed of a combination of children.

  In recent years, there has been a growing demand for using this type of motor for the purpose of improving control performance and high acceleration operation in injection shafts of injection molding machines and press rams of press machines that require high output and large thrust. ing. However, in principle, a linear motor requires a cored system in order to obtain a large thrust, and the magnetic characteristics change greatly depending on the position of the mover relative to the stator, so it is stable at any position of the mover. There is a limit in the output range for driving the machine shaft of an automatic machine, which is important for positioning characteristics where motion characteristics are desired. For example, a detent thrust (a repulsive force generated when an attempt is made to displace the mover in a non-excited state), which is a disturbance thrust generated in the mover according to the position, or a thrust that is a ratio of thrust to thrust current The constant fluctuation (thrust pulsation rate) for each mover position is large.

  As the shape of the electromagnetic steel plate on the stator side (or mover side) employed in the conventional linear motor of this type, the width W1 of the teeth 23 is the mover facing side (or the stator facing side) as shown in FIG. ), Which is the same from the tooth tip side 23b to the tooth root portion side 23a, and the width W2 of the slot 25 is the same from the opening side 25b to the bottom side 25a. "Was common. For this reason, there are few shape parameters that can be selected, which hinders optimal design.

  In addition, the linear motor for the above application is required to have a large thrust and a small mover weight so that high acceleration can be easily realized. However, to reduce the weight of the mover, the size of the mover is reduced, but there is a problem that the total magnetic flux amount is reduced. In order to compensate for this, if the coil current is increased to increase the output torque, the magnetic flux density of the teeth becomes too high, and the leakage magnetic flux between the adjacent teeth increases, resulting in a peak characteristic. That is, it was difficult to satisfy both large thrust and high acceleration.

  As a measure for the above, it is conceivable to increase the width of the teeth of the stator core (or the mover core). However, the slot width is reduced by that amount, and the cross-sectional area of the coil is reduced so that the current cannot be increased. There is.

  Patent Document 1 (Japanese Patent Laid-Open No. 2008-017694) and Patent Document 2 (Japanese Patent Laid-Open No. 2006-025505) show linear motors in which the magnetic saturation limit is increased to improve thrust. The magnetic saturation limit is set high by forming the magnetic pole of the mover so as to become wider as it moves away from the stator.

JP 2008-017694 A JP 2006-025505 A

  However, the above-mentioned detent thrust, which is a disturbance thrust, depends on the relationship between the teeth width and slot width of the stator (or mover) that is close to and facing the mover (or stator), and examines the relationship between the dimensions. Otherwise, good results cannot be obtained in reducing disturbance and obtaining a large thrust. Further, as other disturbance torques, the same applies to the variation (thrust pulsation rate) of the thrust constant, which is the ratio of thrust to thrust current, for each mover position. In Patent Document 1 and Patent Document 2, the optimum setting for satisfying the required performance is not considered for the maximum outputable thrust, the hydraulic pulsation rate, and the detent thrust.

  The present invention reduces the disturbance thrust by setting an appropriate relationship with respect to the teeth and slot widths around which the armature coil is wound, thereby obtaining a uniform and large thrust along the moving position of the mover. In addition, a linear motor capable of performing high acceleration control and an armature structure thereof are provided.

Further, the present invention provides an armature coil wound around an armature having a plurality of permanent magnets arranged side by side and an armature having a plurality of slots and teeth opposed to the permanent magnet array via a magnetic space. In a linear motor provided with a mounted armature, wherein either one of the magnetic pole and the armature is a stator and the other is a mover, and the magnetic pole and the armature are relatively driven.
Width of the tooth of the armature is directed Ke the base portion from the tooth tip, is constant to the center position of the length of the teeth, increased gradually toward the tooth root portion from the central position, the width of the slot The dimension is constant from the opening of the slot toward the bottom to the central position of the length of the slot, and gradually decreases from the central position toward the bottom .

  In the above linear motor, the number of turns of the armature coil wound around the armature is set to be smaller on the tooth root side than on the tooth tip side.

Further, as an armature structure, the width of the teeth of the armature is directed Ke the base portion from the tooth tip, is constant to the center position of the length of the teeth, towards the tooth root portion from the central position gradually And the width dimension of the slot is constant from the opening of the slot toward the bottom to the center position of the length of the slot, and gradually decreases from the center position toward the bottom. .

  In the armature structure, the number of turns of the armature coil wound around the armature is set to be smaller on the tooth root side than on the tooth tip side.

  According to the present invention, by reducing the disturbance thrust, a uniform and large thrust can be obtained along the moving position of the mover, and high acceleration control can be performed.

FIG. 3 is a structural explanatory diagram of stator teeth and slots according to the first embodiment of the present invention. Structure explanatory drawing of the teeth and slots of the stator of Example 2 of the present invention. The structure explanatory drawing of the teeth and slot of the conventional stator. Explanatory drawing of the magnetic line by the armature coil of the slot back part of this invention Example. Explanatory drawing of the magnetic line by the armature coil of the slot opening part of this invention Example.

  Embodiments of the present invention will be described below with reference to the drawings. In the embodiment, a field pole in which a plurality of permanent magnets are arranged side by side is used as a mover, and an armature in which an armature coil is wound around an armature core that faces the field pole via a magnetic space is used as a stator. .

  A first embodiment of the present invention is shown in FIG. DESCRIPTION OF SYMBOLS 1 is the armature (stator) in which the core comprised by laminating | stacking an electromagnetic steel plate extends linearly, 2 is the back part of an armature, 3 is several teeth (3 teeth in the figure) formed in the armature And 5 is a plurality of slots formed between the teeth 3, and 4 is a plurality of armature coils inserted into the slots 5 so as to wind the teeth 3. The tooth 3 has a root portion 3a on the back side of the armature and a tooth tip side 3b, and the slot 5 has a bottom portion 5a on the back side of the armature and an opening portion 5b on the tip side. Reference numeral 8 denotes a mover having a predetermined length that faces the teeth tip 3b and the slot opening 5b side of the armature 1 through a magnetic space and extends linearly, and a plurality of permanent magnets 7 are arranged at a predetermined pitch on the opposing surface. It is buried side by side. In the figure, the coil 4 is shown inserted into only a part of one slot.

  In the above configuration, a three-phase alternating current is passed through the plurality of armature coils 4 wound around the armature 1 of the stator to generate a moving magnetic field in the armature 1, and the permanent magnets 7 are sequentially magnetized to the moving magnetic field. By attracting, the magnetic pole 8 as the mover is linearly moved in the direction of the arrow. Actually, the magnetic pole 8 is moved linearly with a moving table or the like fixed.

  In this embodiment, the width dimension of the tooth 3 at the root portion 3a is Wt5, the width dimension at the tooth tip 3b is Wt4, the width dimension of the bottom 5a of the slot 5 is S5, and the width dimension at the opening 5b is S4. Yes. The width dimension of the tooth 3 of the armature 1 is set so as to gradually increase from the tooth tip 3b toward the tooth root 3a so that Wt4 <Wt5. Further, the width dimension of the slot 5 is set to gradually decrease from the opening 4b toward the bottom 4a so that S4> S5.

  As described above, in the first embodiment, the width WT4 of the tooth tip is made smaller than the width WT5 of the tooth root, and the width S4 at the slot opening 5b is made smaller than the width S5 at the slot bottom 5a. It has a larger shape.

  FIG. 3 shows a conventional armature (stator) shape. Here, the armature 21 has the same outer dimensions as the armature 1 in FIG. 1, and the tooth shape has a width dimension of the root 23a (corresponding to WT5 in FIG. 1) and a width dimension of the tooth tip 23b (corresponding to WT4 in FIG. 1). ) Are the same W1, and the width of the slot is the same width W2 at the bottom 25a and the opening 25b.

  When the number of windings and the number of parallel windings wound around the armature teeth are the same and the current flowing into the windings is the same, the teeth of the armature 21 in FIG. The magnetic saturation in the portion is relaxed, and the effective magnetic flux amount in the tooth portion is increased. As a result, the maximum value of torque that can be output can be increased. However, if the width of the teeth is increased, the width of the slot is reduced, so that there is a problem that the number of winding turns is reduced and the generated magnetic flux is reduced. The magnetic flux that has flowed into the tooth 23 of the core of the armature 21 tends to flow to the back portion 22 having a small magnetic resistance, and the magnetism tends to concentrate on the root portion 3a of the tooth and is easily saturated. Therefore, in Example 1, the effective magnetic flux in the tooth portion is increased by increasing the width of the root portion 3a from the tip 3b of the tooth 3 to alleviate magnetic saturation.

  Here, the shapes of the teeth and the slots can be freely selected, but it is not easy to achieve both the maximum output thrust and the uniform thrust characteristics at each position. In particular, in order to improve the acceleration performance of the movable part of the machine, it is necessary to reduce the weight of the movable element of the motor itself to be driven, and this determines the length of the movable element. Since the shape of the stator on the side of the mover (the dimensions of the teeth and slots) is related to the length of the mover, the dimension given to the teeth cannot be made very small, and there is a limit.

  A second embodiment of the present invention is shown in FIG. The same parts as those in FIG. In the second embodiment, the width (Wt4) of the tooth portion 3 of the armature 1 is a section (predetermined from the tooth tip side 3b toward the root side 3a to a position 3c at the center of the length of the tooth portion 3. ) And constant (Wt4). And it increases gradually toward the root side 3a from the said position 3c, and becomes the width dimension Wt5 in the root side 3a. Further, the width dimension (S4) of the slot 5 is constant (S4) in a section (predetermined length section) from the opening 5b toward the bottom 5a to a position 5c at the center of the length of the slot 5. . Then, it gradually decreases from the position 5c toward the bottom 5a, and becomes a width dimension S5 at the bottom 5a.

  In the second embodiment, as in the previous embodiment, the ratio of the width dimension between the teeth 3 and the slots 5 (tooth width dimension / slot width dimension) gradually increases from the tip of the teeth toward the root.

  Accordingly, the width dimension of the tooth root 3a is made as large as possible Wt5 in the same manner as in the first embodiment, the magnetic saturation is relaxed, and the effective magnetic flux in the tooth portion is increased.

  According to the above embodiment, the opening 5b and the bottom 5a of the slot 5 have different width dimensions and have a relationship of S4> S5. Therefore, the armature coil 4 has a large number of turns in the vicinity of the opening 5b, and the bottom 5a Less. Therefore, the magnetic flux due to the coil current increases near the opening 5b of the slot 5 and decreases at the bottom 5a. 4 shows the flow of magnetic flux by the coil at the bottom 5a of the slot 5, and FIG. 5 shows the flow of magnetic flux by the coil near the opening side 5b of the slot 5.

  The magnetic flux generated by the coil 4 at the bottom portion 5a of the slot 5 generates a circular magnetic flux centering on the bottom portion 5a. Therefore, as shown in FIG. In this embodiment, since the slot width dimension is set so that the magnetic flux generated by the coil near the bottom 5a of the slot 5 is reduced, the leakage magnetic flux between the teeth can be reduced.

  The magnetic flux generated by the coil 4 in the vicinity of the opening 5b of the slot 5 generates a circular magnetic flux centering on the coil 4. However, since the tooth tip 5b is close as shown in FIG. It acts effectively as the thrust of the mover. In this embodiment, the slot width is set so that the magnetic flux generated by the coil on the opening 5b side of the slot 5 is increased, so that the thrust of the mover can be further increased. In addition, since the width of the tooth root 3a is set to be large, the magnetic resistance of the tooth root 3a is lowered, so that almost all of the magnetic flux generated by the coil on the opening 5b side can pass through the back portion 2 of the armature 1. Characteristic deterioration due to saturation and leakage magnetic flux between teeth can be prevented.

  When the armature 1 is used as the stator of this embodiment and the linear motor is configured by combining the armature 1 and the magnetic pole 8 as the mover, the required maximum output possible thrust while having the same size and the weight of the mover. The most advantageous linear motor characteristics can be realized with respect to the weight of the mover, the injection performance of the injection molding machine can be improved, the control performance can be improved, and the press performance and quality of the press machine can be improved.

  DESCRIPTION OF SYMBOLS 1 ... Armature core (stator), 2 ... Back part of armature, 3 ... Teeth, 3a ... Teeth root, 3b ... Teeth tip, 3c ... Teeth center position, 4 ... Armature coil, 5 ... Slot, 5a ... Slot Bottom part, 5b ... slot opening part, 5c ... slot center part, 7 ... permanent magnet, 8 ... mover.

Claims (4)

A magnetic pole in which a plurality of permanent magnets are arranged side by side, and an armature in which an armature coil is wound around an armature having a plurality of slots and teeth on the opposing surface while facing the permanent magnet array via a magnetic space. A linear motor configured to travel relatively between the magnetic pole and the armature, with one of the magnetic pole and the armature as a stator and the other as a mover,
Width of the tooth of the armature is directed Ke the base portion from the tooth tip, is constant to the center position of the length of the teeth, increased gradually toward the tooth root portion from the central position, the width of the slot A linear motor characterized in that the dimension is constant from the opening of the slot toward the bottom to the central position of the length of the slot and gradually decreases from the central position toward the bottom .   2. The linear motor according to claim 1, wherein the number of turns of the armature coil wound around the armature is set to be smaller on the tooth root side than on the tooth tip side. A magnetic pole in which a plurality of permanent magnets are arranged side by side, and an armature in which an armature coil is wound around an armature having a plurality of slots and teeth on the opposing surface while facing the permanent magnet array via a magnetic space. In an armature structure of a linear motor , wherein either one of the magnetic pole and the armature is a stator and the other is a mover, and the magnetic pole and the armature are relatively driven.
Width of the tooth of the armature is directed Ke the base portion from the tooth tip, is constant to the center position of the length of the teeth, increased gradually toward the tooth root portion from the central position, the width of the slot A linear motor armature structure , characterized in that the dimension is constant from the opening of the slot toward the bottom to the center position of the length of the slot and gradually decreases from the center position toward the bottom . 4. The linear motor armature structure according to claim 3, wherein the number of turns of the armature coil wound around the armature is set smaller on the tooth root side than on the tooth tip side . Armature structure .

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