JPH11332211A - Cylindrical linear motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cylindrical linear motor whose stator core poles can be excited without stator windings on the poles and which can output a larger thrust than a cylindrical stepping motor. SOLUTION: A mover 32 is composed of a straight movable shaft 27, a magnet attachment unit 29 and annular permanent magnets 31a-31h which are attached to the magnet attaching part 30 of the magnet attachment unit 29 so as to have N-poles and S-poles arranged alternately. A plurality of stator cores 35 are fixed to the inner wall of a frame 5 in the circumferential direction of the mover 32 with the same intervals. Annular windings composed of winding conductors annularly wound around the mover 32 so as to surround the circumference of the mover 32 are used as field windings 39a-39e. The parts of the field windings 39a-39e are respectively fitted to slots formed between adjacent pole parts 35c arranged in the axial direction of the plurality of stator cores 35.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder type linear synchronous motor in which a mover is arranged inside a stator and moves linearly.

[0002]

2. Description of the Related Art 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.

[0003]

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

An object of the present invention is to provide a cylinder type linear synchronous motor capable of obtaining a large thrust and having a simple structure.

Another object of the present invention is to provide a cylinder type linear synchronous motor which 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 capable of extending the life of a linear bearing supporting a linear motion shaft.

A further object of the present invention is to provide a cylinder type linear synchronous motor which can extend the life of a linear bearing for supporting a linear motion shaft and can obtain a larger thrust.

Another object of the present invention is to provide a cylinder type linear synchronous motor having a built-in position detecting 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 a 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 cylinder type linear synchronous motor in which the structure and assembly of the mover are simple.

[0013]

In the cylinder type linear synchronous motor according to 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. Generally, a ball spline is used as a linear bearing.

The mover includes a linear motion shaft supported by a pair of linear bearings so as to be able to reciprocate linearly, a magnet mounting fixed to the linear motion shaft, disposed in a cavity of the frame, and extending in the axial direction of the linear motion shaft. A magnet mounting body made of a magnetically permeable material having a portion,
The magnet mounting body is provided with at least one permanent magnet row composed of a plurality of permanent magnets that are supported by a magnet mounting portion and that are arranged in the axial direction such that N poles and S poles appear alternately on a magnetic pole surface. Is done. The plurality of permanent magnets constituting one permanent magnet row may be a plurality of physically separated permanent magnets, or one 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, it is preferable that the plurality of permanent magnet rows are arranged at substantially equal intervals in the circumferential direction. However, an assembly of permanent magnet rows may be formed using an annular permanent magnet magnetized such 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 periphery 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, respectively. . The use of such an annular permanent magnet not only simplifies the structure of the mover,
Attachment of the permanent magnet to the magnet attachment body is facilitated.

The stator has a magnetic pole surface facing one or more rows of permanent magnets in the radial direction of the base and the linear motion shaft fixed to the inner peripheral side of the case frame, and is arranged at a predetermined interval in the axial direction. At least one stator core having a plurality of magnetic pole portions formed therein, and a plurality of excitation windings for exciting each magnetic pole portion such that magnetic poles of a predetermined polarity appear on the magnetic pole surfaces of the plurality of magnetic pole portions of the one or more stator cores. And a line. 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 the cylinder type linear synchronous motor, the moving magnetic field is generated by changing the direction of the exciting current flowing through the plurality of exciting 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. 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. 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 AC 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 magnetic pole portion according to the idea of the rotating electric machine. If the idea of the rotating electric machine is introduced into the 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. And one or more stator cores adjacent in the axial direction
A structure is adopted in which a part of one excitation winding corresponding to a slot formed between two magnetic pole portions 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,
Magnetic poles having different polarities appear on the magnetic pole surfaces of two adjacent magnetic pole portions. 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
This corresponds to a rotating magnetic field used in a polyphase synchronous motor. Due to this moving magnetic field, 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 direct acting 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 p-phase (where p is a positive integer of 2 or more) exciting current having a different phase is applied to a plurality of exciting windings to obtain a moving magnetic field, m pieces (where m is a positive integer of 2 or more) are obtained. When the stator core is used, m stator cores are arranged at substantially equal intervals in the circumferential direction. As the plurality of exciting windings, p × q (where q is a positive integer of 1 or more) annular windings are prepared. 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 when the axial dimension of the slot (the distance between two adjacent magnetic pole portions) is reduced, the stator can be easily configured.

When the annular winding used as the exciting winding is formed, the exciting winding is formed on 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 be wound. In this case,
A part of the bobbin is fitted in the slot. The bobbin around which each excitation winding is wound may be independent for each excitation winding,
Each bobbin 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 constituting the permanent magnet array mounted on the magnet mounting portion of the magnet mounting body are formed of a plurality of magnetic pole surfaces. When the gap between the pole face of the magnetic pole portion and the pole face of the stator is made substantially flat so as to be substantially constant, the gap between the pole face of the stator and the pole face of the mover does not substantially change. ,
The largest thrust is obtained magnetically, and it is possible to prevent a biased force from being applied to the linear motion shaft. 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 contour of the magnet mounting body of the mover with the permanent magnet fixed is a so-called square shape.

Like the mover of the rotating electric machine, 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 with the permanent magnet fixed is substantially circular. In this case, since the components constituting the mover and the stator can be manufactured using the manufacturing equipment of the rotating electric machine, the manufacturing cost can be reduced. In this 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 that 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 detecting sensor for detecting the positional relationship between the mover and the stator in the axial direction in order to switch the exciting current flowing through the exciting winding. It is conceivable to provide a position detection sensor so as to detect the displacement of the linear motion shaft protruding outside the case. However, in such a 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, 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 mounted on 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 detected portion. 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 part is located closer to the output shaft part to which the load of the direct drive shaft is connected than the permanent magnet row. It is preferable to arrange them. In this case, the detection unit is naturally arranged at a position close to the output shaft to which the load is connected. With this arrangement, 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 a 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 portion and the 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 detection 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 detecting sensor may be formed on the outer periphery of the magnet mounting body on the output shaft side.

The end bracket on the side on which the linear bearing supporting the end of the pair of end brackets on the side of the non-output shaft to which the load on the linear shaft is not connected is attached to the end of the linear shaft protruding from the end bracket. A cover member covering the end on the output shaft side may be attached. By doing so, 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, moisture can be prevented from entering 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 above and the linear motion shaft is vertically displaced.

It is preferable that the stator core is attached to the frame as follows. A plurality of fitting grooves are formed in the inner peripheral portion of the frame so that the bases of the plurality of stator cores can be inserted from one opening end side 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. Then, in a state where the base of the stator core is fitted in 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 with respect 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 function to prevent the stator core from being displaced in the axial direction by receiving a reaction force acting on the stator core in the axial direction. Because of this function, it is possible to prevent cracks and the like from entering the mold portion due to the application of force to the mold portion.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 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 cylinder type 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 aluminum end brackets 7.
And 9. 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 the 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 on 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. Note that the end brackets 7 and 9
5 fixed.

A pair of linear bearings 11 and 13 support a linear motion shaft 27 made of iron so as to be able to reciprocate linearly. 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. Case 3
An iron magnet mounting body 29 made of a magnetic material is fixed to a portion of the linear motion shaft 27 located inside the linear motion shaft 27 so as to be concentric with the linear motion shaft 27. The magnet mounting body 29 basically has a cylindrical shape, and has inside thereof fitting holes 29a fitted on the outer periphery of the linear motion shaft 27, and positioned on both sides of the fitting holes 29a. Thus, 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.
c also has a diameter that does not contact the outer peripheral surface of the linear bearing 13. 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).
On the outer periphery of the sensor, a detected part 5 of a position detection sensor described later is provided.
A step 29d to which the linear scale used as 1 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 permanent magnets and on the axially outer side of the annular permanent magnet 31h. . Stopper members 33 are provided on the outer peripheral portion of the magnet mounting portion 30.
A fitting groove into which is fitted is formed. 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 to which the annular permanent magnets 31a to 31h are fitted, the heat-shrinkable tube is heated and thermally shrunk, thereby forming the entire annular permanent magnets 31a to 31h. It may be wrapped around. Toroidal permanent magnet 31
a, 31c, 31e and 31g are magnetized so that the N pole appears on the outer surface in the radial direction, and the annular permanent magnet 31
b, 31d, 31f and 31h are magnetized so that the N pole appears on the outer surface in the radial direction. As a result, the linear motion shaft 27
, A row of permanent magnets in which N poles and S poles are alternately arranged in the axial direction is formed. Note that each of the annular permanent magnet portions facing the seven magnetic pole portions of the six stator cores described below
A plurality of permanent magnets constituting a plurality of permanent magnet rows arranged at predetermined intervals in the circumferential direction in the present invention are configured. In this example, the linear motion shaft 27 and the magnet mounting body 29
The mover 32 is constituted by the ring-shaped permanent magnets 31a to 31h.

The manner in which the magnet mounting body 29 is fixed to the linear motion shaft 27 is arbitrary. In this example, four pins 34 are provided in four fitting holes provided in the circumferential direction at two locations on the linear motion shaft 27. And the magnet mounting body 29 is fixed to the linear motion shaft 27.

Six stator cores 35 are fixed to the inner periphery of the frame 5. Six stator cores 35 ...
Are bases 35 fixed to the inner peripheral side of the frame 5, respectively.
a and the magnetic pole faces 35b in the radial direction of the linear motion shaft 27 face the permanent magnet rows formed by the annular permanent magnets 31a to 31h, and are arranged at a predetermined interval in the axial direction of the linear motion shaft 27. It has seven magnetic pole portions 35c.
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-teeth-shaped steel plates are laminated 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 peripheral portion of the frame 5 is arbitrary. In this example, six fitting grooves 5 that can be inserted into the inner peripheral portion of the frame 5 from one opening end (the opening end on the end bracket 9 side) side.
are formed at equal intervals in the circumferential direction. These fitting grooves 5c are provided with the stator core 3 on the other open end (open end on the end bracket 7 side) side of the frame 5.
5 is provided with a stopper surface 5d for contacting one end surface in the axial direction for positioning the stator core 35. 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 connected to the frame 5 by welding or screwing.
It is firmly fixed against.

The six slots formed between two adjacent magnetic pole portions 35c of each stator core 35 have exciting windings 39a to 39g formed of annular windings formed by winding winding conductors in an annular shape.
A part of 39f is fitted respectively. In the example of FIG. 1, each of the excitation windings 39a to 39f 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 in 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. Each excitation winding is configured 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. Each excitation winding 3
The lead wire 40 from 9a to 39f is routed using this space 43 and connected to a feeder wire or a lead wire of a predetermined excitation winding. Although it is essentially unnecessary to use the bobbin 41, use of the bobbin 41 greatly improves workability and insulation.

In this example, the stator cores 35, the excitation windings 3
9a 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 part 45 is shown by a broken line. The stopper surface 5d and the stopper member 37 are connected to the stator core 35.
Performs a function of preventing the stator cores 35 from being displaced in the axial direction by receiving a reaction force in the axial direction acting on the stator cores 35. Because of this function, it is possible to prevent a crack or the like from entering the mold portion 45 due to a force applied to the mold portion 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 is a position detecting sensor for detecting the positional relationship between the mover 32 and the stator 47 in the axial direction in order to switch the exciting current flowing through the exciting windings 39a to 39f. Need. 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 such a 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.
A position detection sensor 49 for detecting a positional relationship in the axial direction with the position is disposed inside the frame 5. The position detection sensor 49 is an optically or magnetically detectable detected 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 moving amount of the detected portion 51. And a detection unit 53 for detecting magnetically or magnetically. In the 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 light to the detection target 51 from the detection unit 53 including the light emitting unit and the light receiving unit. 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 near 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 near the output shaft part 27a. When the 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 detection 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 output shaft portion 27
The expansion of each part located from the a side to the non-output shaft side 27b accumulates and appears as a change in the mounting position of the detected part and the detection part. On the other hand, if 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 side of the linear motion shaft 27 as in this example, the detected part 51 and the detecting
Since the cumulative value of the thermal expansion that changes the mounting position of the motor 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 shown in FIG. 1, the end bracket 9 on the side to which the linear bearing 13 for supporting the end of the non-output shaft portion 27b to which the load of the direct acting shaft 27 is not connected projects from the end bracket 9. Non-output shaft portion 2 of the linear motion shaft 28
A cover member 55 made of metal or synthetic resin that covers the end on the 7b side 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 direct drive 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 cylindrical linear synchronous motor, the direction of the excitation current flowing through the excitation 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 the stator cores 35. , A moving magnetic field is generated, and 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 is generated. 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, a multi-phase synchronous motor is obtained, so that a large thrust can be obtained. If the exciting current is not changed (the polarity and the 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.

The excitation mode of the excitation windings 39a to 39f of this embodiment will be briefly described with reference to FIGS.
First, in this example, the electrical angle is shifted by 120 degrees every 3 degrees.
The phase excitation currents U, V and W are used. Therefore, the two stator slots 35 fitted into the two adjacent slots of the six stator cores 35.
A U-phase exciting current is applied to the two exciting windings 39a and 39b, and a V-phase exciting current is applied to the two exciting windings 39c and 39d fitted to two adjacent slots. Then, a W-phase exciting current is passed through the two annular windings 39e and 39f fitted into the two adjacent slots next to it. Then, the six excitation windings 39a to 39f are connected so that the polarities appearing in the two magnetic pole portions 35c adjacent to each other in the axial direction of the six stator cores 35 have different polarities. In this example, in order to generate the magnetic flux flow shown in FIG.
A lead wire is connected to b so that a U-phase excitation current flows in the opposite direction, and a 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 so that the V-phase excitation current flows in the opposite directions, 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 such 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.

With the above connection, the position detection sensor 49
By switching the exciting current flowing through each exciting winding based on the output of the motor, an apparent moving magnetic field that moves in the axial direction is generated, and the movable element 32 is moved in the axial direction by the same operating principle as that of the synchronous motor. Go to 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 (where p is a positive integer of 2 or more) exciting currents having different phases to a plurality of exciting windings, m pieces (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. As the plurality of exciting windings, p × q (where q is a positive integer of 1 or more) annular windings are prepared. N for one stator core
In this case, n is n = p × q
+1 relationship. And n-1 formed between two magnetic pole portions adjacent to each other in the axial direction of the m stator cores.
A part of one corresponding annular winding is fitted into each of the slots. 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 distance 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 way, 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 annular permanent magnets 31a to 31
Although h is used, it is needless to say that the permanent magnet array provided corresponding to each stator core 35 may be constituted by a plurality of independent permanent magnets. In this 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, six stator cores 35 are arranged at substantially equal intervals in the circumferential direction, but theoretically one stator core may be used. However, one stator core
In other words, a force biased in one radial direction acts on the linear motion shaft due to the suction force acting between the mover and the stator, and the force acts on the linear bearing to shorten the life of the linear bearing. Therefore, it is preferable to arrange a plurality of stator cores with good magnetic balance as in this example. Further, if 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.

As in the mover of the above example, 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 with the permanent magnet fixed is substantially circular. In this case, since the components constituting 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, a plurality of magnetic pole portions 1 of the stator core 135 are provided.
When the magnetic pole surface 135b of the magnet 35c is configured to be substantially flat, and a plate-shaped magnet is used as the plurality of permanent magnets 131 constituting the permanent magnet array attached to the magnet attachment portion 130 of the magnet attachment 129, the permanent magnet 131 Are flattened, and the gap size between the magnetic pole surfaces 135b of the plurality of magnetic pole portions 135c is substantially constant. In this case, since 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, the largest thrust is obtained magnetically, and the linear motion shaft Is 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 mounting body 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 cylindrical linear synchronous motor.

When the rectangular cylinder type linear synchronous motor shown in FIG. 7 is constructed, as shown in FIG.
31 is tilted little by little, i.e., skewed,
It is preferable to arrange them on the 29 magnet mounting portions 130. FIG.
In the example, the 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. Then, the permanent magnet 131 is set so that a polarity different from that of the adjacent permanent magnet appears between the pins 140 on the magnetic pole surface.
Is disposed between the two pins 140. In this way, the corners of the adjacent magnets attract each other due to the attractive force,
As shown in the figure, the skew is alternately inclined (skewed) in different directions. 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. By employing such a mounting structure of the permanent magnet 131, the cogging torque can be improved. 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. .

[0044]

In the cylinder type linear synchronous motor of the present invention, the moving direction is changed by changing the direction of the exciting current flowing through the plurality of exciting 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. Generates a magnetic field to generate a thrust between one or more permanent magnet rows and a plurality of magnetic pole parts that displaces the direct-acting axis in the axial direction, so that a larger thrust than a known cylinder-type linear stepping motor is obtained. Can be. In particular, according to 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, 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.

[Brief description of the drawings]

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.

FIG. 2 is a half cross-sectional view of FIG. 1;

FIG. 3 is a schematic perspective view of the stator of the example of FIG. 1;

FIG. 4A is a perspective view of a bobbin, and FIG. 4B is a cross-sectional view of the bobbin with an exciting winding wound thereon.

FIG. 5 is a view used to explain an arrangement state of excitation windings on a stator side of the cylindrical linear three-phase synchronous motor of FIG. 1;

FIG. 6 is a diagram showing a relationship between a stator and a mover of the cylindrical linear three-phase synchronous motor of FIG. 1;

FIG. 7 is a diagram showing a relationship between a stator and a mover when the present invention is applied to a rectangular cylinder type linear synchronous motor.

8 is a view used to explain an example of a method of mounting permanent magnets in the rectangular cylinder linear synchronous motor of FIG. 7;

[Explanation of symbols]

 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)

[Claims] 1. A pair of linear bearings attached to both ends of a case having a cylindrical frame, a linear motion shaft supported by the pair of linear bearings so as to be able to reciprocate linearly, and fixed to the linear motion shaft. A magnet mounting body made of a magnetically permeable material having a magnet mounting portion disposed in the frame and extending in the axial direction of the linear motion shaft; and a magnet mounting portion supported by the magnet mounting portion of the magnet mounting body and alternately having N A mover including at least one permanent magnet row composed of a plurality of permanent magnets arranged in the axial direction so that a pole and an S pole appear; a base fixed to an inner peripheral side of the frame; and the linear motion shaft One or more stator cores having a plurality of magnetic pole portions whose magnetic pole faces face the one or more permanent magnet rows in the radial direction and are arranged at predetermined intervals in the axial direction;
A stator having a plurality of exciting windings for exciting the plurality of magnetic pole portions of the stator core, wherein the direction of an exciting current flowing through the plurality of exciting windings is changed to form the plurality of magnetic pole portions. A moving magnetic field is generated by changing the polarity of a magnetic pole appearing on a magnetic pole surface, and a thrust for displacing the linear motion shaft in the axial direction is generated between the one or more permanent magnet rows and the plurality of magnetic pole portions. A cylindrical linear synchronous motor configured as described above, wherein 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 a circumferential direction. A part of one excitation winding corresponding to a slot formed between two magnetic pole portions adjacent to the one or more stator cores in the axial direction is fitted. Cylinder type linear synchronous motor. 2. A cylindrical frame having a cavity therein, a pair of end brackets fixed to both ends of the frame, a pair of linear bearings attached to the pair of end brackets, and the pair of linear bearings A linear motion shaft supported so as to be capable of linear reciprocating motion, a magnetically permeable material fixed to the linear motion shaft, disposed in the cavity of the frame, and provided with a magnet mounting portion 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 alternately appear on the magnetic pole surfaces. A mover having m rows (where m is a positive integer of 2 or more) of permanent magnet rows arranged at intervals, a base fixed to the inner peripheral side of the frame, and magnetic poles in a radial direction of the translation shaft Face M stator cores having n (where n is a positive integer of 3 or more) magnetic pole portions facing at least m rows of permanent magnet rows and arranged at predetermined intervals in the axial direction; A stator having a plurality of exciting windings for exciting each magnetic pole portion such that a magnetic pole of a predetermined polarity appears on the magnetic pole surface of the n magnetic pole portions of the m stator cores; A moving magnetic field is generated by flowing an exciting current of a p-phase (where p is a positive integer of 2 or more) having a different phase to the exciting winding and changing the polarity of the magnetic poles appearing on the magnetic pole surfaces of the plurality of magnetic pole portions. A cylindrical linear device configured to generate a thrust for displacing the translation shaft in the axial direction between the m rows of permanent magnet rows and the n magnetic pole portions of the m stator cores. A synchronous motor, wherein the m stator cores are substantially equal in a circumferential direction of the mover Are spaced interval, said plurality of excitation windings, p × the winding conductor so that each surround the movable element in the circumferential direction is wound annularly
It consists of q (where q is a positive integer of 1 or more) annular windings, n is in a relationship of n = p × q + 1, and two of the m stator cores adjacent to each other in the axial direction are A cylindrical linear synchronous motor, wherein a part of one of said annular windings respectively corresponding to n-1 slots formed between magnetic pole portions is fitted. 3. The cylinder-type linear synchronous motor according to claim 1, wherein the excitation winding is wound around a bobbin made of an insulating material, and a part of the bobbin is fitted in the slot. 4. The magnetic pole faces of the plurality of magnetic pole portions of the stator core are configured to be substantially flat, and form the permanent magnet row mounted on the magnet mounting portion of the magnet mounting body. The cylinder-type linear synchronous motor according to claim 1, wherein the pole faces of the plurality of permanent magnets are substantially flat so that a gap between the pole faces of the plurality of pole portions is substantially constant. 5. The cylinder-type linear synchronous motor according to claim 2, wherein the number of the m stator cores is an even number. 6. The cylinder-type linear synchronous motor according to claim 1, wherein a position detection sensor for detecting a positional relationship between the mover and the stator in the axial direction is disposed inside the frame. . 7. The position detection sensor comprises: an optically or magnetically detectable detection target attached to the movable element; and a position or movement amount of the detection target fixed to the frame. The magnet mounting body of the mover and the frame are formed of materials having different thermal expansion coefficients, and the detected part is more than the permanent magnet row. 7. The cylinder-type linear synchronous motor according to claim 6, wherein the linear linear motor is arranged at a position close to an output shaft to which a load of the linear motion shaft is connected. 8. The end bracket on the side to which 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 on the linear motion shaft is not connected projects from the end bracket. The cylinder type linear synchronous motor according to claim 1 or 2, further comprising a cover member that covers an end of the linear motion shaft on the non-output shaft side. 9. A plurality of fitting grooves into 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 fitting groove has a stopper surface on the other open end side of the frame, which is in contact with the one end surface of the stator core in the axial direction to position the stator core. In a state where the base portion is fitted in the fitting groove and the one end face of the stator core is in contact with the stopper face, a stopper member that contacts the other end face in the axial direction of the stator core is provided. The cylinder-type linear synchronous motor according to claim 1, wherein the stator core, the plurality of excitation windings, and the stopper member are fixed to the frame with an insulating molding material. 10. A plurality of annular permanent magnets magnetized so that N poles or S poles appear on a radially outer surface of an outer peripheral portion of the magnet mounting body of the mover, and N poles in the axial direction. And the S pole are alternately arranged at predetermined intervals in the axial direction, and the portion of the annular permanent magnet facing the magnetic pole portion of the one or more stator cores is the permanent magnet. The cylinder-type linear synchronous motor according to claim 1, wherein the plurality of permanent magnets forming a row are formed. 11. The cylinder type according to claim 10, wherein the stator core is formed by stacking a plurality of comb-shaped steel plates so that the magnetic pole surface of the stator core is formed in an arc shape. Linear synchronous motor.