JP2004236498A - Cylinder type linear synchronous motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a cylinder-type linear synchronous motor in which a magnetic pole part is excited without an excitation winding to the magnetic pole part of a stator core, with thrust force larger than that of a cylinder-type linear stepping motor. <P>SOLUTION: A movable unit 32 is constituted by fitting annular permanent magnets 31a to 31h so as to arrange an N/S pole alternately in the direction of an axial line in a magnet mounting part 30 of a magnet mounting body 29 fixed to a direct acting shaft 27. A plurality of stator cores 35 are fixed to an inner wall part of a frame 5 with an equal gap provided in a perimeter direction of the movable unit 32. As excitation windings 39a to 39e, an annular winding, formed by annularly winding a winding conductor so as to respectively surround the circumference of the movable unit 32 in the perimeter direction, is used. Parts of the excitation windings 39a to 39e are fitted respectively to slots formed between two magnetic pole parts 35c adjacent in the direction of the axial line of a plurality of the stator cores 35. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a cylinder-type linear synchronous motor in which a mover is arranged inside a stator and performs linear motion.

  At present, a cylinder type linear stepping motor (or linear pulse motor) is actually sold as a cylinder type linear motor. This commercially available cylindrical linear stepping motor has a fixed stator comprising a plurality of stator cores having a plurality of small teeth formed on an inner peripheral surface thereof along an axial direction of a linear motion shaft and an excitation winding wound thereon. And a movable element fixed to the linear motion shaft and having a permanent magnet therein and having a movable portion having a plurality of small teeth formed on the outer peripheral surface along the axial direction of the linear motion shaft. In this linear stepping motor, the excitation windings of the plurality of stator cores are sequentially excited to generate a thrust between the small teeth of the stator and the small teeth of the mover, thereby causing the linear motion shaft to move linearly.

  Although a linear stepping motor has high position control performance, it cannot obtain a large thrust. Therefore, it is not suitable for applications requiring a large load torque of 7 torque.

  An object of the present invention is to provide a cylinder type linear synchronous motor which can obtain a large thrust and has a simple structure.

  Another object of the present invention is to provide a cylinder-type linear synchronous motor that does not require winding an exciting winding around a stator core.

Another object of the present invention is to provide a cylinder-type linear synchronous motor that can extend the life of a linear bearing that supports a linear motion shaft.

  It is still another object of the present invention to provide a cylinder type linear synchronous motor capable of extending the life of a linear bearing supporting a linear motion shaft and obtaining a larger thrust.

  Another object of the present invention is to provide a cylinder type linear synchronous motor having a built-in position detection sensor for detecting a positional relationship between a mover and a stator.

  Another object of the present invention is to provide a cylinder-type linear synchronous motor having high detection accuracy of a positional relationship between a mover and a stator.

  Another object of the present invention is to provide a cylinder type linear synchronous motor having high waterproof performance.

  Another object of the present invention is to provide a cylinder type linear synchronous motor which is easy to assemble and has high mechanical strength.

  Another object of the present invention is to provide a cylindrical linear synchronous motor in which the structure and assembly of the mover are simple.

  In the cylinder type linear synchronous motor of the present invention, a pair of linear bearings is attached to both ends of a case having a cylinder type frame. Specifically, a pair of linear bearings are respectively attached to a pair of end brackets fixed to both ends of a cylindrical frame having a cavity therein. As a linear bearing, a ball spline is generally used.

  The mover includes a linear motion shaft supported by a pair of linear bearings so as to be capable of linear reciprocating motion, and a magnet mounting portion fixed to the linear motion shaft, disposed in a cavity of the frame, and extending in the axial direction of the linear motion shaft. And a plurality of permanent magnets supported by the magnet mounting portion of the magnet mounting body and arranged in the axial direction such that N poles and S poles appear alternately on the magnetic pole surface. And one or more rows of permanent magnets. The plurality of permanent magnets that constitute one permanent magnet row may be a plurality of physically separated permanent magnets, or a physically magnetic body may alternately have N poles and S poles in the longitudinal direction. A plurality of permanent magnets configured to be magnetized may be used.

  When there are a plurality of permanent magnet rows, the plurality of permanent magnet rows are preferably arranged at substantially equal intervals in the circumferential direction. However, an assembly of permanent magnet rows may be configured using an annular permanent magnet magnetized so that an N pole or an S pole appears on the outer surface in the radial direction. Specifically, annular permanent magnets are fitted and fixed so that N poles and S poles are alternately arranged at predetermined intervals in the axial direction on the outer peripheral portion of the magnet mounting body of the mover. When such a plurality of toroidal permanent magnets are used, portions of the plurality of toroidal permanent magnets facing the plurality of magnetic pole portions of the stator core become a plurality of permanent magnets constituting a permanent magnet row. . Use of such an annular permanent magnet not only simplifies the structure of the mover, but also facilitates attachment of the permanent magnet to the magnet mounting body.

  The stator has a base fixed to the inner peripheral side of the frame of the case and a plurality of magnetic pole faces facing one or more permanent magnet rows in the radial direction of the linear motion shaft and arranged at predetermined intervals in the axial direction. One or more stator cores having a magnetic pole part, and a plurality of excitation windings for exciting each magnetic pole part such that a magnetic pole of a predetermined polarity appears on the magnetic pole surfaces of the plural magnetic pole parts of the one or more stator cores. Be composed. In terms of magnetic balance, it is preferable that there be a plurality of stator cores, and that the plurality of stator cores be arranged at substantially equal intervals in the circumferential direction so as to face the plurality of permanent magnet rows of the mover, respectively. preferable.

  In a cylinder-type linear synchronous motor, a moving magnetic field is generated by changing the direction of excitation current flowing through a plurality of excitation windings of a stator to change the polarity of magnetic poles appearing on the magnetic pole surfaces of a plurality of magnetic pole portions. A thrust that displaces the direct-acting shaft in the axial direction is generated between the permanent magnet row and the plurality of magnetic pole portions. If the exciting current is an alternating current, the polarity of the magnetic pole appearing on the magnetic pole surface of the magnetic pole portion changes according to the frequency. When a multi-phase alternating current is applied to a plurality of excitation windings, a multi-phase synchronous motor is obtained, so that a large thrust can be obtained. If the polarity and magnitude of the exciting current are fixed, only the attractive force acts between the stator and the mover, and the position of the mover is fixed.

  When exciting the magnetic pole portion of the stator core, a winding conductor is wound around the outer periphery of the magnetic pole portion according to the idea of the rotating electric machine. When the idea of this rotating electric machine is brought into a linear synchronous motor, the length in the axial direction becomes longer and the winding work of the winding becomes difficult. Therefore, in the present invention, as the plurality of excitation windings of the stator, annular windings each formed by winding a winding conductor in an annular manner so as to surround the mover in the circumferential direction are used. Then, a structure is adopted in which a part of one excitation winding corresponding to a slot formed between two magnetic pole portions adjacent in the axial direction of one or more stator cores is fitted. In this case, the magnetic flux generated by the excitation winding fitted in one slot flows so as to circulate through two adjacent magnetic pole portions, and magnetic poles having different polarities are formed on the magnetic pole surfaces of the two adjacent magnetic pole portions. appear. By appropriately switching the exciting current flowing through the plurality of exciting windings fitted into the plurality of slots of the one or more stator cores, the stator is moved from one axial direction to the other (or the other direction). (From one direction to the other direction), a moving magnetic field in the same state that the magnetic fields of the north pole and the south pole are moving at a predetermined speed is obtained. This moving magnetic field corresponds to a rotating magnetic field used in the polyphase synchronous motor. Due to this moving magnetic field, a thrust is generated between the plurality of magnetic pole portions of the stator core and the row of permanent magnets of the mover, and the translation shaft moves in the axial direction. If the magnetic poles appearing on the magnetic pole surfaces of the plurality of magnetic pole portions of the stator core are made constant, only the attractive force is generated between the mover and the stator, and the mover is fixed.

  When a moving magnetic field is obtained by supplying p-phase (p is a positive integer of 2 or more) exciting currents having different phases to a plurality of exciting windings, m (where m is a positive integer of 2 or more) fixed When child cores are used, m stator cores are arranged at substantially equal intervals in the circumferential direction. Further, p × q (where q is a positive integer of 1 or more) annular windings are prepared as the plurality of excitation windings. Assuming that one stator core is provided with n magnetic pole portions, in this case, n has a relationship of n = p × q + 1. Then, a part of each corresponding one of the annular windings is fitted into n-1 slots formed between two magnetic pole portions adjacent to each other in the axial direction of the m stator cores. In this way, a perfectly synchronized moving magnetic field can be generated from the n magnetic pole portions of the m stator cores. Since it is only necessary to fit the annular winding into the slot, even if the axial dimension of the slot (the interval between two adjacent magnetic pole portions) is reduced, the stator can be easily configured.

  When configuring the annular winding used as the exciting winding, the exciting winding is wound around a bobbin made of an insulating material from the viewpoints of workability of winding work, improvement of winding density, and protection of the exciting winding. It is preferred to configure. In this case, a part of the bobbin is fitted into the slot. The bobbin on which each exciting winding is wound may be independent for each exciting winding, or the bobbins may be connected integrally.

  The magnetic pole surfaces of the plurality of magnetic pole portions of the stator core are configured to be substantially flat, and the magnetic pole surfaces of the plurality of permanent magnets forming the permanent magnet row attached to the magnet mounting portions of the magnet mounting body are formed of the plurality of magnetic pole portions. When the gap between the pole face of the stator and the pole face of the mover is substantially flat so that the gap between the pole face and the pole face is substantially constant, there is substantially no change in the gap dimension between the pole face of the stator and the pole face of the mover. As a result, the largest thrust can be obtained, and the application of a biased force to the linear motion shaft can be prevented. Therefore, a large force is not applied to the linear bearing, and the life of the linear bearing can be extended. With such a configuration, the cross-sectional shape of the outline of the magnet mounting body of the mover in a state where the permanent magnet is fixed is a so-called square shape.

  When the magnetic pole surface of the permanent magnet is formed in an arc shape so that the cross-sectional shape of the magnet mounting body of the mover in a state where the permanent magnet is fixed is substantially circular, like the mover of the rotating electric machine. In addition, since the components forming the mover and the stator can be manufactured using the manufacturing equipment of the rotating electric machine, the manufacturing cost can be reduced. In such a case, the magnetic pole surfaces of the plural magnetic pole portions of the stator core should be curved so that the variation in the gap size between the magnetic pole surfaces of the plural magnetic pole portions of the stator core and the magnetic pole surfaces of the permanent magnets does not become too large. preferable. Like the stator core of the rotating electric machine, the stator core is configured by stacking a plurality of steel plates. In this case, a plurality of comb-teeth-shaped steel plates provided with teeth forming a plurality of magnetic pole portions are used. Then, a plurality of comb-shaped steel plates are laminated so that the magnetic pole surface of the stator core becomes arc-shaped (curved). In this case, in order to simplify the structure of the mover, the above-described annular permanent magnet may be used.

  Unlike a linear stepping motor, a linear synchronous motor requires a position detection sensor for detecting a positional relationship between a mover and a stator in an axial direction in order to switch an exciting current flowing through an exciting winding. Although it is conceivable to provide a position detection sensor so as to detect the displacement of the linear motion shaft protruding to the outside of the case, this method is inconvenient because it cannot be handled with the same feeling as an existing motor. In addition, in this case, a detection error due to thermal expansion of each member due to a temperature change becomes large, and there is a problem that position control accuracy is deteriorated. Therefore, if the position detection sensor for detecting the positional relationship between the mover and the stator in the axial direction is disposed inside the frame, the above problem can be almost solved. The position detection sensor is an optically or magnetically detectable object attached to the mover, and is fixed to the inner peripheral portion of the frame to optically or magnetically detect the position or the amount of movement of the object to be detected. And a detection unit that detects the current time. In this case, when the magnet mounting body and the frame of the mover are formed of materials having different thermal expansion coefficients, the detected portion is located closer to the output shaft portion to which the load of the direct acting shaft is connected than the permanent magnet row. It is preferable to arrange them. In this case, the detection unit is naturally disposed at a position near the output shaft to which the load is connected. With this configuration, the position detection sensor is disposed at a position near the output shaft to which the load is connected, so that the error detected by the sensor is reduced. If the position detection sensor is arranged on the non-output shaft side opposite to the output shaft portion of the direct acting shaft, the expansion of each part located from the output shaft side to the non-output shaft side accumulates and the detected part and the detected part are detected. It appears as a change in the mounting position of the part. On the other hand, when the detected portion and the detecting portion of the position detecting sensor are arranged at a position close to the output shaft portion side of the linear motion shaft, the accumulated value of thermal expansion that changes the mounting position of the detected portion and the detecting portion is small. Therefore, the detection accuracy of the position detection sensor increases, and the positioning accuracy of the linear synchronous motor increases accordingly. It should be noted that a portion for mounting the detected portion of the position detection sensor may be formed on the outer periphery of the magnet mounting body on the output shaft side.

  In addition, the end bracket on the side where the linear bearing that supports the end of the pair of end brackets on the side of the non-output shaft to which the load of the direct-acting shaft is not connected is mounted on the end bracket on the side where the linear bearing projects from the end bracket. A cover member that covers the side end may be attached. In this way, the non-output shaft portion and the linear bearing portion of the linear motion shaft can be protected. In particular, if a cover having a waterproof structure is used, it is possible to prevent moisture from entering the inside of the motor from the non-output shaft side of the direct acting shaft. Such a function is particularly effective when the linear synchronous motor of the present invention is used in a posture in which the non-output shaft portion side of the linear motion shaft is positioned on the upper side and the linear motion shaft is vertically displaced.

  Also, it is preferable to attach the stator core to the frame as follows. A plurality of fitting grooves are formed in the inner periphery of the frame so that the bases of the plurality of stator cores can be inserted from one opening end of the frame. The plurality of fitting grooves are provided on the other open end side of the frame with stopper surfaces for contacting one end surface of the stator core in the axial direction for positioning the stator core. When the base of the stator core is fitted into the fitting groove and one end face of the stator core is in contact with the stopper face, the stopper member that comes into contact with the other end face in the axial direction of the stator core is attached to the frame. And fix it. Further, the stator core, the plurality of excitation windings and the stopper member are molded with an insulating molding material. The stopper surface and the stopper member have a function of preventing the stator core from being displaced in the axial direction by receiving an axial reaction force acting on the stator core. Because of this function, it is possible to prevent a crack or the like from entering the mold portion due to a force applied to the mold portion.

  In the cylinder type linear synchronous motor of the present invention, the moving magnetic field is generated by changing the direction of the excitation current flowing through the plurality of excitation windings of the stator to change the polarity of the magnetic poles appearing on the magnetic pole surfaces of the plurality of magnetic pole portions. Since a thrust for displacing the direct-acting shaft in the axial direction is generated between one or more permanent magnet rows and the plurality of magnetic pole portions, a larger thrust can be obtained than a known cylinder-type linear stepping motor. In particular, according to the present invention, as the plurality of exciting windings of the stator, an annular winding formed by winding a winding conductor in an annular manner so as to surround the mover in the circumferential direction is used, and the axis of the stator core is used. Since a structure is adopted in which a part of the exciting winding corresponding to the slot formed between two magnetic pole parts adjacent in the direction is fitted, it is not necessary to wind the exciting winding around the magnetic pole part of the stator core. . Therefore, according to the present invention, a cylinder-type linear synchronous motor capable of generating a large thrust can be configured with a simple structure.

  Hereinafter, an example of an embodiment of the present invention will be described in detail. FIG. 1 is a partially cutaway sectional view of an example of an embodiment in which the present invention is applied to a cylindrical linear three-phase synchronous motor 1, and FIG. 2 is a half transverse sectional view of FIG. The case 3 of the cylindrical linear three-phase synchronous motor 1 includes a cylindrical frame 5 made of a non-magnetic material (for example, aluminum) and a pair of end brackets 7 and 9 made of aluminum. The frame 5 has a cylindrical cavity 5a inside, and has annular steps 5b, 5b into which end brackets 7 and 9 are fitted inside openings at both ends. Linear bearings 11 and 13 made of ball splines are fitted into openings 7a and 9a at the center of the end brackets 7 and 9, respectively. The linear bearings 11 and 13 are fixed to the end brackets 7 and 9 with four screws 15. Annular grooves 7c and 9c that open radially outward are formed in the outer peripheral portions of the annular protrusions 7b and 9b fitted to the steps 5b and 5b of the frame 5 of the pair of end brackets 7 and 9. O-rings 17 and 19 for sealing are fitted in the grooves 7c and 9c. As shown in FIG. 2, the end brackets 7 and 9 are integrally provided with flange portions 7d and 9d each having a substantially quadrangular contour, and a mounting bolt is inserted into each of the four corners of the flange portions. Holes 21 and 23 are respectively formed. The end brackets 7 and 9 are fixed to the frame 5 by screws 25.

  A pair of linear bearings 11 and 13 support an iron linear motion shaft 27 capable of linearly reciprocating. The state shown in FIG. 1 is a state in which the output shaft portion 27a to which the load of the linear motion shaft 27 is connected projects outmost. An iron magnet mount 29 made of a magnetic material is fixed to the portion of the linear motion shaft 27 located inside the case 3 so as to be concentric with the linear motion shaft 27. The magnet mounting body 29 basically has a cylindrical shape, and has therein a fitting hole 29a fitted on the outer periphery of the linear motion shaft 27, and is located on both sides of the fitting hole 29a. First and second large-diameter holes 29b and 29c having a larger diameter than the fitting hole 29a are formed. The first large-diameter hole 29 b has a diameter that does not contact the outer peripheral surface of the inner end of the linear bearing 11, and the second large-diameter hole 29 c has a diameter that does not contact the outer peripheral surface of the linear bearing 13. have. The outer periphery of the portion of the magnet mounting body 29 where the first large-diameter hole 29b is formed (the end of the direct-acting shaft 27 on the output shaft portion 27a side) serves as a detected portion 51 of a position detection sensor described later. A step 29d to which a linear scale to be used is attached is formed. The outer peripheral portion of the portion where the second large-diameter hole 29c is formed constitutes the magnet mounting portion 30. The magnet mounting portion 30 has a substantially cylindrical shape extending in the axial direction of the linear motion shaft 27, and eight annular permanent magnets 31a to 31h are fitted around its outer periphery. A substantially annular or C-shaped stopper member 33, which is made of a nonmagnetic material and partially cut, is fitted between two adjacent annular annular permanent magnets and axially outside the annular annular permanent magnet 31h. . A fitting groove into which the stopper members 33 are fitted is formed in the outer peripheral portion of the magnet mounting portion 30. The annular permanent magnets 31a to 31h may be fixed to the magnet mounting portion 30 via an adhesive, or the entire annular permanent magnets 31a to 31h may be molded with a synthetic resin. Further, after a heat-shrinkable tube is put on the outside of the magnet mounting portion 30 in which the annular permanent magnets 31a to 31h are fitted, the heat-shrinkable tube is heated and thermally shrunk, so that the annular permanent magnets 31a to 31h are entirely formed. You may make it wrap around. The toroidal permanent magnets 31a, 31c, 31e and 31g are magnetized such that N poles appear on the outer surface in the radial direction, and the toroidal permanent magnets 31b, 31d, 31f and 31h have S poles on the outer surface in the radial direction. Is magnetized so that appears. As a result, a row of permanent magnets in which N poles and S poles are alternately arranged in the axial direction of the linear motion shaft 27 is formed. The annular permanent magnet portions facing the seven magnetic pole portions of the six stator cores described later constitute a plurality of permanent magnet rows arranged at predetermined intervals in the circumferential direction in the present invention. To form a plurality of permanent magnets. In this example, the mover 32 is constituted by the linear motion shaft 27, the magnet mounting body 29, and the annular permanent magnets 31a to 31h.

  The manner in which the magnet mounting body 29 is fixed to the translation shaft 27 is arbitrary, but in this example, the pins 34 are fitted into four fitting holes provided in two places on the translation shaft 27 in the circumferential direction. The magnet mounting body 29 is fixed to the translation shaft 27.

  Six stator cores 35 are fixed to the inner periphery of the frame 5. The six stator cores 35 have permanent magnets whose magnetic pole surfaces 35b are formed by annular permanent magnets 31a to 31h in the radial direction of the base portion 35a and the translation shaft 27, which are fixed to the inner peripheral side of the frame 5, respectively. There are seven magnetic pole portions 35c opposed to the row and arranged at a predetermined interval in the axial direction of the linear motion shaft 27. The stator core 35 is configured by laminating a plurality of steel plates. As the steel plate, a plurality of comb-teeth-shaped steel plates having teeth forming the magnetic pole portions 35c are used. Then, a plurality of comb-shaped steel plates are stacked so that the magnetic pole surface 35b of the stator core is formed in an arc shape (curved). The laminated steel plates are mutually connected by laser welding or the like. The six stator cores 35 are arranged at substantially equal intervals in the circumferential direction (60-degree intervals in this example) such that the magnetic pole surfaces 35b face the permanent magnet rows of the mover, respectively.

  The structure for fixing the base 35a of the stator core 35 to the inner periphery of the frame 5 is arbitrary. In this example, six fitting grooves 5c, which can be inserted from one opening end (opening end on the end bracket 9 side) side, are formed in the inner peripheral portion of the frame 5 at equal intervals in the circumferential direction. . The fitting groove 5c is positioned on the other open end (open end on the end bracket 7 side) side of the frame 5 in contact with one axial end face of the stator core 35 to position the stator core 35. 5d is provided. The base 35a of the stator core 35 is press-fitted into the fitting groove 5c. An annular stopper member 37 is provided on the inner peripheral portion of the frame 5 so that one end surface in the axial direction of the stator core 35 contacts the other end surface in the axial direction of the stator core 35 in a state of contact with the stopper surface 5d. Fixed against. The stopper member is firmly fixed to the frame 5 by welding, screwing, or the like.

  In six slots formed between two adjacent magnetic pole portions 35c of each stator core 35, a part of the excitation windings 39a to 39f formed of annular windings formed by winding winding conductors in an annular shape. Each is fitted. In the example of FIG. 1, each of the excitation windings 39 a to 39 f is configured by winding a winding conductor around a synthetic resin bobbin 41 as shown in FIGS. 4A and 4B. An exciting winding is fitted into each slot together with a part of 41. 2 and 3, the bobbin 41 is omitted for easy understanding. The bobbin has a structure in which two annular flanges 41b are coupled to both ends of a cylindrical portion 41a, and a winding conductor 39 covered with an insulating material is wound between the two flanges 41b, 41b. Each excitation winding is constituted by being turned. In FIG. 4B, reference numeral 40 denotes a lead wire of the exciting winding. As can be seen from the schematic perspective views shown in FIGS. 2 and 3, six spaces 43 extending in the axial direction are formed between two adjacent stator cores 35. The lead wire 40 from each of the excitation windings 39a to 39f is routed using this space 43 and connected to a feeder line or a lead wire of a predetermined excitation winding. Although it is essentially unnecessary to use the bobbin 41, the use of the bobbin 41 greatly improves workability and insulation.

  In this example, the stator cores 35, the excitation windings 39a to 39f, and the stopper member 37 are molded with an insulating molding material to form a molded portion 45. In FIG. 1, the mold portion 45 is indicated by a broken line. The stopper surface 5d and the stopper member 37 function to prevent the stator cores 35 from being displaced in the axial direction by receiving the reaction force acting on the stator cores 35 in the axial direction. Because of this function, it is possible to prevent a crack or the like from entering the mold part 45 due to a force applied to the mold part 45. In this example, the stator 47 is constituted by the stator cores 35 and the excitation windings 39a to 39f.

  Unlike the linear stepping motor, the linear synchronous motor requires a position detection sensor for detecting the positional relationship between the mover 32 and the stator 47 in the axial direction in order to switch the excitation current flowing through the excitation windings 39a to 39f. I do. It is conceivable to provide a position detection sensor so as to detect the displacement of the linear motion shaft 27 protruding outside the case. However, in this case, the motor cannot be handled with the same feeling as an existing motor, which is inconvenient. In addition, in this case, a detection error due to thermal expansion of each member due to a temperature change becomes large, and there is a problem that position control accuracy is deteriorated. Therefore, in this example, as shown in FIG. 1, a position detection sensor 49 for detecting a positional relationship between the mover 32 and the stator 47 in the axial direction is disposed inside the frame 5. The position detection sensor 49 is an optically or magnetically detectable portion 51 attached to the mover 32 and is fixed to the inner peripheral portion of the frame 5 to optically detect the position or the amount of movement of the portion 51. And a detection unit 53 for detecting magnetically or magnetically. In a position detection sensor that optically detects a position, a linear scale having a predetermined reflection pattern is used as the detection target 51. Then, the position is detected based on information contained in the light reflected by irradiating the detected portion 51 with light from the detecting portion 53 having the light emitting portion and the light receiving portion. In this example, the magnet mounting body 29 and the frame 5 of the mover 32 are formed of materials having different thermal expansion coefficients. Therefore, the detected part 51 is arranged at a position close to the output shaft part 27a to which the load of the linear motion shaft 27 is connected, and the detection part 53 is also arranged at a position close to the output shaft part 27a. When heat transmitted from the load side through the output shaft portion 27a of the linear motion shaft 27 is transmitted to the inside of the case 3 of the motor 1 through the linear motion shaft 27, the linear motion shaft 27, the magnet mounting body 29, and the frame 5 thermally expand. Cause If the position detecting sensor is arranged on the non-output shaft portion 27b side of the linear motion shaft 27 opposite to the output shaft portion 27a, the expansion of each portion located on the non-output shaft portion side 27b from the output shaft portion 27a side accumulates. It appears as a change in the mounting position of the detected part and the detection part. On the other hand, when the detected part 51 and the detecting part 53 of the position detecting sensor 49 are arranged at a position close to the output shaft part side of the linear motion shaft 27 as in this example, Is small, the detection accuracy of the position detection sensor 49 increases, and the positioning accuracy of the linear synchronous motor increases accordingly.

  In the example of FIG. 1, the end bracket 9 on which the linear bearing 13 that supports the end on the non-output shaft portion 27b side to which the load of the direct drive shaft 27 is not connected is mounted has a direct drive shaft protruding from the end bracket 9. A cover member 55 made of metal or synthetic resin that covers the end of the non-output shaft portion 27b on the side of the non-output shaft portion 27b is attached. When the cover member 55 is provided, the non-output shaft portion 27b of the linear motion shaft 27 and the linear bearing portion 13 can be protected. In particular, in this example, the cover member 55 having a waterproof structure is used. Specifically, an annular fitting groove that opens in a direction toward the outer surface of the end bracket 9 is formed in the flange portion 55a of the cover member 55, and the O-ring 57 for sealing is compressed in this fitting groove. Are fitted. The cover member 55 is screwed into the end bracket 9 by inserting screws into a plurality of through holes (not shown) provided in the flange portion 55a. With such a structure, it is possible to prevent moisture from entering the motor from the non-output shaft portion 27b side of the linear motion shaft 27. Such a function is particularly effective when the linear three-phase synchronous motor 1 is used in a posture in which the non-output shaft portion side 27b of the linear motion shaft 27 is positioned above and the linear motion shaft 27 is vertically displaced. Demonstrate.

  In the cylinder type linear synchronous motor, the direction of the exciting current flowing through the exciting windings 39a to 39f of the stator 47 is changed to change the polarity of the magnetic poles appearing on the magnetic pole surfaces 35b of the magnetic pole portions 35c of each stator core 35. Generates a moving magnetic field, and generates a thrust for displacing the linear motion shaft 27 in the axial direction between the permanent magnet row of the mover 32 and the magnetic pole portions 35c of the stator 47. In this example, a sine wave three-phase alternating current is used as the exciting current. The polarity of the magnetic pole appearing on the magnetic pole surfaces 35b of the magnetic pole portions 35c changes according to the frequency of the three-phase alternating current. When a multi-phase AC current is applied to the exciting winding, the motor becomes a multi-phase synchronous motor, so that a large thrust can be obtained. If the exciting current is not changed (the polarity and magnitude are fixed), only the attractive force acts between the stator 47 and the mover 32, and the position of the mover 32 is fixed.

  Excitation modes of the excitation windings 39a to 39f in this example will be briefly described with reference to FIGS. First, in this example, three-phase excitation currents U, V, and W whose phases are shifted by 120 degrees in electrical angle are used. Therefore, a U-phase exciting current is applied to the two exciting windings 39a and 39b fitted to the two adjacent slots of the six stator cores 35,. A V-phase excitation current is passed through the two exciting windings 39c and 39d to be fitted, and the W-phase exciting current is applied to the two annular windings 39e and 39f fitted to two adjacent slots next to the two exciting windings. Of the excitation current. Then, the six excitation windings 39a to 39f are connected such that the polarities appearing at two magnetic pole portions 35c adjacent to each other in the axial direction of the six stator cores 35 are different from each other. In this example, in order to generate the magnetic flux flow shown in FIG. 5, a lead wire is connected to the excitation windings 39a and 39b through which the U-phase excitation current flows so that the U-phase excitation current flows in opposite directions. Then, the U-phase power supply line is connected to the connected lead wire. The symbols shown in FIG. 5 indicate the direction in which the current flows. The excitation windings 39c and 39d through which the V-phase excitation current flows also connect the lead wires such that the V-phase excitation current flows in the opposite direction, and connect the V-phase power supply line to the connected lead wires. Similarly, the excitation windings 39e and 39f, through which the W-phase excitation current flows, are connected to the lead wires so that the W-phase excitation current flows in the opposite directions, and the W-phase power supply line is connected to the connected lead wires. Connecting.

  By connecting the wires in this way and switching the exciting current flowing through each exciting winding based on the output of the position detection sensor 49 to generate a moving magnetic field apparently moving in the axial direction, the same as the principle of the synchronous motor, According to the operation principle described above, the mover 32 moves in the axial direction. When the switching of the excitation current is stopped, only the attractive force acts between the mover 32 and the stator 47, and the mover 32 stops.

  The excitation mode used in this example is generally described as follows. First, when a moving magnetic field is obtained by supplying p-phase (p is a positive integer of 2 or more) excitation currents having different phases to a plurality of excitation windings, m (where m is a positive integer of 2 or more) Are used, m stator cores are arranged at substantially equal intervals in the circumferential direction. Further, p × q (where q is a positive integer of 1 or more) annular windings are prepared as the plurality of excitation windings. Assuming that one stator core is provided with n magnetic pole portions, in this case, n has a relationship of n = p × q + 1. Then, a part of each corresponding one of the annular windings is fitted into n-1 slots formed between two magnetic pole portions adjacent to each other in the axial direction of the m stator cores. In this way, a perfectly synchronized moving magnetic field can be generated from the n magnetic pole portions of the m stator cores. Since it is only necessary to fit the annular winding into the slot, even if the axial dimension of the slot (the interval between two adjacent magnetic pole portions) is reduced, the stator can be easily configured. When the thrust is increased by using a multi-phase excitation current, the same phase of excitation is applied to q annular windings fitted in q slots continuously arranged in the axial direction of the m stator cores. Apply current. Also in this case, p × q annular windings are connected so that the polarities appearing at two magnetic pole portions adjacent to each other in the axial direction of the m stator cores are different from each other. In this case, the wiring does not become complicated even in the case of multi-phase. In order to increase or decrease the thrust, the number of annular windings through which the same phase exciting current flows may be increased or decreased. In the example of FIG. 1, three exciting windings are prepared for one phase in order to further increase the thrust. In that case, the number of magnetic pole portions of each stator core is 10, and the number of excitation windings is 9.

  In the above example, the ring-shaped permanent magnets 31a to 31h are used. However, it is needless to say that a permanent magnet array provided corresponding to each stator core 35 may be constituted by a plurality of independent permanent magnets. In that case, a plurality of permanent magnet rows are provided at intervals in the circumferential direction of the mover 32 in practice.

  In the above example, the six stator cores 35 are arranged at substantially equal intervals in the circumferential direction, but theoretically one stator core may be used. However, when one stator core is used, a force biased in one direction in the radial direction acts on the linear motion shaft due to an attraction force acting between the mover and the stator, and the force acts on the linear bearing, so that the linear bearing To shorten the life of the device. Therefore, it is preferable to arrange a plurality of stator cores with good magnetic balance as in this example. Further, when the number of stator cores is increased, the resultant thrust increases accordingly, so the number of stator cores may be determined according to the thrust to be obtained.

  Like the mover of the above example, when the magnetic pole surface of the permanent magnet is formed in an arc shape so that the cross-sectional shape of the contour of the magnet mounting body of the mover with the permanent magnet fixed is substantially circular. In addition, since the components forming the mover and the stator can be manufactured using the manufacturing equipment of the rotating electric machine, the manufacturing cost can be reduced. However, in this structure, the gap size between the magnetic pole surface 35b of the magnetic pole portion 35c of the stator core 35 and the magnetic pole surface of the permanent magnet varies. Therefore, as shown in FIG. 7, the magnetic pole surfaces 135b of the plurality of magnetic pole portions 135c of the stator core 135 are configured to be substantially flat, and a permanent magnet row mounted on the magnet mounting portion 130 of the magnet mounting body 129 is configured. When a plate-shaped magnet is used as the plurality of permanent magnets 131, the magnetic pole surfaces 131a of the permanent magnets 131 become flat, and the gap between the magnetic pole surfaces 135b of the plurality of magnetic pole portions 135c becomes substantially constant. . By doing so, the gap dimension between the magnetic pole surface 135b of the stator 147 and the magnetic pole surface 131a of the mover 132 does not substantially change, so that the largest thrust can be obtained magnetically and the linear motion shaft can be obtained. , Can be prevented from being generated. Therefore, a biased force is not applied to the linear bearing, and the life of the linear bearing can be extended. With such a configuration, the cross-sectional shape of the outline of the magnet mount 129 of the mover 132 in a state where the permanent magnet 131 is fixed is a so-called square shape, which is a square-cylinder linear synchronous motor.

  When the rectangular cylinder type linear synchronous motor shown in FIG. 7 is configured, as shown in FIG. 8, the permanent magnets 131 are arranged on the magnet mounting portion 130 of the magnet mounting body 129 by being slightly tilted, that is, skewed. preferable. In the example of FIG. 8, cylindrical pins 140 are fixed on the plane of the magnet mounting portion 130 of the magnet mounting body 129 at intervals in the axial direction. The permanent magnet 131 is arranged between the two pins 140 such that a polarity different from that of the permanent magnet adjacent to the pin 140 appears on the magnetic pole surface. By doing so, the corners of the adjacent magnets are attracted by the attraction force, and the magnets are alternately inclined (skewed) in different directions as shown in the figure. In this state, a heat-shrinkable tube is placed around the magnet mounting portion 130, and the heat-shrinkable tube is contracted, so that the permanent magnets 131 are fixed to the magnet mounting portion 130 in a state where they are inclined with respect to the axial direction. Can be. If such a mounting structure of the permanent magnet 131 is employed, the cogging torque can be improved. Of course, the structure for skewing the permanent magnet may be applied to the example of FIG.

  Note that the excitation mode or method of the excitation winding described in the above example is merely an example, and the excitation method of the excitation winding in practicing the present invention is arbitrary as long as it can generate a moving magnetic field.

BRIEF DESCRIPTION OF THE DRAWINGS It is a partially broken sectional view of an example of an embodiment in which the present invention is applied to a cylindrical linear three-phase synchronous motor. FIG. 2 is a half cross-sectional view of FIG. 1. It is a schematic perspective view of the stator of the example of FIG. (A) is a perspective view of a bobbin, (B) is a cross-sectional view of a state in which an exciting winding is wound around the bobbin. FIG. 2 is a diagram used to explain an arrangement state of excitation windings on a stator side of the cylindrical linear three-phase synchronous motor in FIG. 1. FIG. 2 is a diagram illustrating a relationship between a stator and a mover of the cylindrical linear three-phase synchronous motor in FIG. 1. It is a figure which shows the relationship between a stator and a mover when this invention is applied to a square cylinder type linear synchronous motor. FIG. 8 is a view used to explain an example of a method of attaching a permanent magnet in the rectangular cylinder linear synchronous motor of FIG. 7.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Cylinder type linear three-phase synchronous motor 3 Case 5 Frame 7,9 End bracket 11,13 Linear bearing 27 Linear motion shaft 27a Output shaft part 29,129 Magnet attachment body 31a-31h Toroidal permanent magnet 131 Permanent magnet 32,132 Movable 35,135 Stator core 35b, 135b Magnetic pole surface 35c, 135c Magnetic pole portion 39a-39f Excitation winding (annular winding)
41 bobbin 47,147 stator 55 cover member

Claims (11)

A pair of linear bearings attached to both ends of a case having a cylindrical frame,
A magnetically permeable shaft having a linear motion shaft supported by the pair of linear bearings so as to be capable of linear reciprocating motion, and a magnet mounting portion fixed to the linear motion shaft and disposed in the frame and extending in the axial direction of the linear motion shaft. A magnet mounting body made of a material and one or more permanent magnets supported by the magnet mounting portion of the magnet mounting body and including a plurality of permanent magnets arranged in the axial direction such that N poles and S poles alternately appear on the magnetic pole surface. A mover having a row of permanent magnets,
A plurality of magnetic poles whose magnetic pole faces face the one or more permanent magnet rows in the radial direction of the base fixed to the inner peripheral side of the frame and the linear motion shaft and are spaced apart from each other by a predetermined distance in the axial direction. Comprising at least one stator core having a portion and a stator having a plurality of excitation windings for exciting the plurality of magnetic pole portions of the one or more stator cores,
The moving magnetic field is generated by changing the direction of the exciting current flowing through the plurality of exciting windings to change the polarity of the magnetic poles appearing on the magnetic pole surfaces of the plurality of magnetic pole portions, and the one or more permanent magnet rows and the plurality of A cylinder-type linear synchronous motor configured to generate a thrust for displacing the linear motion shaft in the axial direction between the magnetic pole portion,
The plurality of excitation windings of the stator are each configured by winding a winding conductor in an annular manner so as to surround the mover in the circumferential direction,
A cylinder type wherein a part of one excitation winding corresponding to a slot formed between two axially adjacent magnetic pole portions of the one or more stator cores is fitted. Linear synchronous motor. A cylindrical frame having a cavity inside,
A pair of end brackets fixed to both ends of the frame,
A pair of linear bearings attached to the pair of end brackets,
A linear motion shaft supported by the pair of linear bearings so as to be capable of linear reciprocating motion; and a magnet mounting portion fixed to the linear motion shaft, disposed in the cavity of the frame, and extending in the axial direction of the linear motion shaft. And a plurality of permanent magnets supported by the magnet mounting portion of the magnet mounting body and arranged in the axial direction such that N poles and S poles appear alternately on the magnetic pole surface. A mover including m rows (where m is a positive integer of 2 or more) of permanent magnet rows arranged at intervals in a circumferential direction;
A base fixed to the inner peripheral side of the frame and n pieces whose magnetic pole faces are opposed to the m rows or more permanent magnet rows in the radial direction of the linear motion shaft and are arranged at a predetermined interval in the axial direction. (Where n is a positive integer of 3 or more) so that m stator cores having magnetic pole portions and magnetic poles of a predetermined polarity appear on the magnetic pole surfaces of the n magnetic pole portions of the m stator cores. A stator having a plurality of excitation windings for exciting each magnetic pole portion,
A moving magnetic field is generated by passing a p-phase (p is a positive integer of 2 or more) exciting current having a different phase through the plurality of exciting windings and changing the polarity of magnetic poles appearing on the magnetic pole surfaces of the plurality of magnetic pole portions. A cylinder configured to generate a thrust for displacing the linear motion shaft in the axial direction between the m rows of permanent magnet rows and the n magnetic pole portions of the m stator cores. Type linear synchronous motor,
The m stator cores are arranged at substantially equal intervals in the circumferential direction of the mover,
Each of the plurality of excitation windings has p × q (where q is a positive integer of 1 or more) annular windings formed by winding winding conductors so as to surround the mover in the circumferential direction. Consists of lines,
N is in a relationship of n = p × q + 1,
A part of one annular winding corresponding to each of n-1 slots formed between two magnetic pole portions adjacent to each other in the axial direction of the m stator cores is fitted. A cylindrical linear synchronous motor characterized by the above-mentioned.   3. The cylinder type linear synchronous motor according to claim 1, wherein the exciting winding is wound around a bobbin made of an insulating material, and a part of the bobbin is fitted in the slot. The magnetic pole faces of the plurality of magnetic pole portions of the stator core are configured to be substantially flat,
The gap dimension between the magnetic pole faces of the plurality of permanent magnets constituting the row of permanent magnets attached to the magnet mounting portion of the magnet mounting body is substantially constant. 2. The cylindrical linear synchronous motor according to claim 1, which is substantially flat so that   3. The cylindrical linear synchronous motor according to claim 2, wherein the number of the m stator cores is an even number.   3. The cylinder-type linear synchronous motor according to claim 1, wherein a position detection sensor that detects a positional relationship between the mover and the stator in the axial direction is disposed inside the frame. 4. The position detection sensor is an optically or magnetically detectable object attached to the mover, and is fixed to the frame to optically or magnetically detect the position or the amount of movement of the object to be detected. And a detection unit for detecting
The magnet mounting body and the frame of the mover are formed of materials having different thermal expansion coefficients,
7. The cylinder-type linear synchronous motor according to claim 6, wherein the detected portion is located closer to an output shaft portion to which a load of the linear motion shaft is connected than the permanent magnet row.   The linear bracket protruding from the end bracket is provided on the side of the end bracket on which the linear bearing that supports the end of the pair of end brackets on the non-output shaft side to which the load of the linear shaft is not connected is mounted. 3. A cylinder type linear synchronous motor according to claim 1, wherein a cover member for covering an end portion of said non-output shaft portion side is attached. A plurality of fitting grooves in which the bases of the plurality of stator cores can be inserted from one open end side of the frame are formed in an inner peripheral portion of the frame,
The plurality of fitting grooves have a stopper surface for positioning the stator core in contact with the one end surface in the axial direction of the stator core on the other open end side of the frame,
When the base of the stator core is fitted in the fitting groove and the one end face of the stator core is in contact with the stopper face, the stator core comes into contact with the other end face in the axial direction of the stator core. A stopper member to be fixed to the frame,
The cylinder-type linear synchronous motor according to claim 1, wherein the stator core, the plurality of excitation windings, and the stopper member are molded with an insulating molding material. A plurality of annular permanent magnets magnetized such that N poles or S poles appear on the outer surface in the radial direction are provided on the outer peripheral portion of the magnet mounting body of the mover. Are fitted at predetermined intervals in the axial direction so as to be alternately arranged,
The cylinder type linear synchronous motor according to claim 1, wherein a portion of the annular permanent magnet facing the magnetic pole portion of the one or more stator cores constitutes the plurality of permanent magnets constituting the permanent magnet array.   The cylinder-type linear synchronous motor according to claim 10, wherein the stator core is configured by stacking a plurality of comb-teeth-shaped steel plates such that the magnetic pole surfaces of the stator core have an arc shape.

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