JP5473776B2 - Linear motor - Google Patents

Description

  The present invention relates to a linear motor in which a reciprocating rod reciprocates in an axial direction.

  Since a linear motor can be driven at high speed and has high positioning accuracy, the linear motor is used as a driving source for a positioning device, a conveying device, etc. in an industrial product production line or assembly line. A shaft type linear motor includes a magnet assembly formed by arranging a plurality of permanent magnets in a linear direction, and a coil assembly formed by arranging a plurality of cylindrical coils in a linear direction so as to surround the magnet assembly. Have. The plurality of permanent magnets are arranged with their end faces having the same polarity facing each other, and the end faces are abutted against each other to form a magnet assembly. By energizing each coil of the coil assembly, the magnet assembly and the coil assembly are relatively driven in a linear direction by the electromagnetic force between the magnet assembly and the coil assembly. For example, Patent Literature 1 describes a rod-type linear motor in which a magnet assembly is provided on a reciprocating rod on the mover side, and a coil assembly is provided on a housing case on the stator side.

JP 2008-86144 A

  By the way, there is a rod type linear motor in which a magnet assembly is formed by housing a plurality of permanent magnets in a non-magnetic metal pipe provided in a reciprocating rod. In addition, there is one in which a coil assembly is formed by winding a plurality of coils around an outer peripheral surface of a cylindrical bobbin through which a reciprocating rod is inserted. The bobbin is made of a nonmagnetic metal material in order to improve the heat dissipation against heat generation of the coil.

  When the bobbin is formed of a non-magnetic metal material in this way, seizure may occur due to sliding contact between the pipe formed of the metal material and the bobbin. A bearing member is attached to the housing case, and a predetermined gap (air gap) is provided between the pipe and the bobbin so that the pipe does not contact the inner peripheral surface of the bobbin. Therefore, the distance between the magnet assembly and the coil assembly is increased by a predetermined gap between the pipe and the bobbin. For this reason, the electromagnetic force acting on the magnet assembly and the coil assembly is reduced, and the thrust of the linear motor is reduced. Further, if a bearing member is provided in the housing case in order to prevent seizure due to sliding contact between the metal materials of the bobbin and the pipe, the number of parts of the linear motor increases and the structure of the linear motor becomes complicated.

  An object of the present invention is to improve the thrust of a linear motor.

  Another object of the present invention is to simplify the structure of a linear motor.

The linear motor of the present invention is a linear motor that reciprocates in the axial direction by projecting a reciprocating rod that is reciprocally attached to a housing case from the housing case, and has a plurality of permanent magnets having end faces of the same polarity. It is accommodated in a state of being abutted against each other, a projecting shaft portion is provided at one end, a pipe made of a nonmagnetic metal material constituting the reciprocating rod, and fixed to the accommodation case, on the outer peripheral surface of the pipe A supporting inner peripheral surface that is in contact with the entire axial direction is formed in the entire axial direction , and a pipe-shaped resin bobbin that supports the entire supporting inner peripheral surface so as to reciprocate, and the bobbin so as to surround each permanent magnet. a plurality of coils wound around the outer peripheral surface, provided at the other end of the pipe, an annular member that reciprocates with the accommodating case which is formed in the guide hole in the reciprocation of the reciprocating rod, said ring A screw shaft member that is screw-coupled to the inner peripheral surface of the member, presses the plurality of permanent magnets inserted into the pipe, and protrudes radially inward from the inner peripheral surface of the housing case to support the fitting of the bobbin; And when the reciprocating rod moves to the projecting limit position, one end surface of the annular member is opposed to a predetermined gap and abuts against the one end surface to restrict movement of the reciprocating rod; When the reciprocating rod is moved to the retreat limit position, the other end face of the annular member is opposed to the other end face with a predetermined interval when the guide hole is provided in the housing case and the reciprocating rod moves to the retreat limit position. And a cover for restricting the movement of the reciprocating rod .

  The linear motor of the present invention is characterized in that a plurality of partition members for partitioning the plurality of coils from each other are formed integrally with the bobbin.

  The linear motor of the present invention is characterized in that the plurality of coils are resin-molded with a heat-dissipating resin material.

  According to the present invention, the support inner peripheral surface of the resin bobbin is brought into contact with the outer peripheral surface of the nonmagnetic metal pipe, so that the pipe and the bobbin formed of the metal material do not slide and contact each other. Compared with the case where a predetermined gap is provided between the pipe and the bobbin, the distance between the permanent magnet and the coil can be reduced. Thereby, the electromagnetic force which acts on a permanent magnet and a coil becomes large, and it can improve the thrust of a linear motor. In addition, since the pipe is supported by the bobbin so as to be able to reciprocate, there is no need to provide a bearing member separately from the bobbin, and the number of parts of the linear motor can be reduced, simplifying the structure of the linear motor and reducing costs. Can be planned.

  According to the present invention, since the partition member is formed integrally with the bobbin, the number of parts of the linear motor can be reduced as compared with the case where the partition member is provided separately from the bobbin, and the structure of the linear motor Simplification and cost reduction.

  According to the present invention, since each coil is resin-molded with a heat-dissipating resin (heat-dissipating resin), it is possible to improve the heat-dissipating property of the coil against heat generation. Therefore, compared to the case where the bobbin is formed from a metal material, when the bobbin is formed from a resin material, the heat dissipation of the coil against heat generation is reduced. Thus, it is possible to sufficiently ensure heat dissipation against the heat generation of the coil.

It is sectional drawing of the linear motor which is one embodiment of this invention. It is sectional drawing which follows the AA line in FIG. It is sectional drawing which follows the BB line in FIG. It is sectional drawing which shows the linear motor as a comparative example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the motor 10 is a rod-type linear motor that reciprocates a reciprocating rod 11 with a constant stroke in its axial direction, that is, in a linear direction. The motor 10 has a reciprocating rod 11 as a mover extending in the axial direction, and a housing case 12 as a stator on which the reciprocating rod 11 is reciprocally mounted.

  The reciprocating rod 11 has a pipe 13 formed of a nonmagnetic metal material such as stainless steel. The pipe 13 constituting the reciprocating rod 11 has a thin cylindrical shape extending in the axial direction of the reciprocating rod 11 and is formed to be open at both ends thereof. A projecting shaft 14 made of non-magnetic metal such as duralumin is fixed by caulking to one end of the pipe 13, and one end of the pipe 13 is closed by the projecting shaft 14. A connection hole 14 a for connecting a driven member (not shown) to the reciprocating rod 11 is formed on one end face of the protruding shaft portion 14 formed in a substantially cylindrical shape. A driven member is connected to the reciprocating rod 11 by a screw member fastened to the connecting hole 14 a, and the driven member is reciprocated in the axial direction together with the reciprocating rod 11.

  An annular member 15 made of a nonmagnetic metal such as stainless steel is fixed to the other end of the pipe 13 by welding. The annular member 15 has an outer diameter that is larger than the outer diameter of the pipe 13 and an inner diameter that is slightly larger than the inner diameter of the pipe 13, and the pipe 13 is connected to the other end via the annular member 15. Open to the side. A female screw portion 15 a is formed on the inner peripheral surface of the annular member 15, and a screw shaft member 16 is fixed to the annular member 15 with screws. The screw shaft member 16 is formed of a nonmagnetic metal material such as an aluminum alloy, and includes a male screw portion 16 a that is screwed to the female screw portion 15 a of the annular member 15 and a pressing portion 16 b that protrudes into the pipe 13. It has a cylindrical shape with a mark.

  A magnet assembly 17 is provided in the pipe 13 between the projecting shaft portion 14 and the screw shaft member 16. The magnet assembly 17 includes a plurality of solid (cylindrical) permanent magnets 18 magnetized in the axial direction, and the plurality of permanent magnets 18 are alternately axially oriented with their magnetic poles in opposite directions. Are arranged side by side. The plurality of permanent magnets 18 are clamped between the projecting shaft portion 14 and the screw shaft member 16 against the magnetic repulsion force acting on the end surfaces of the magnets of the same polarity facing each other. As a result, the plurality of permanent magnets 18 are accommodated in the pipe 13 in a state where the end surfaces of the magnets having the same polarity are abutted against each other. That is, the plurality of permanent magnets 18 formed to have the same axial length are fastened with the magnet end surfaces having the same polarity against the magnetic repulsion force being brought into contact with each other to form the magnet assembly 17. Yes. As a result, the magnetic flux concentrates in the radial direction in the vicinity of the end surfaces of the permanent magnets 18 abutted against each other, and a high magnetic flux density is generated in the radial direction. In the present embodiment, the magnet assembly 17 is formed in the pipe 13 by fastening a plurality of permanent magnets 18 inserted into the pipe 13 between the protruding shaft portion 14 and the screw shaft member 16. However, the structure of the reciprocating rod 11 is not limited to this.

On the other hand, the housing case 12 made of a nonmagnetic metal such as an aluminum alloy has a rectangular shape with a substantially rectangular cross section extending in the axial direction of the reciprocating rod 11, and the coil housing hole 20 penetrating in the axial direction in the axial center. Is formed. The coil housing hole 20 is provided with a resin bobbin 21 positioned on one end side of the housing case 12. The bobbin 21 has a thin cylindrical shape (pipe shape) extending in the axial direction of the reciprocating rod 11. Yes. One end 21 a of the bobbin 21 is fitted to the inner peripheral surface of a cylindrical fastening member 22 screwed to one end of the coil housing hole 20. One end of the reciprocating rod 11 projects from the one end of the housing case 12 through the fastening member 22. Further, the other end portion 21 b of the bobbin 21 is fitted to the inner peripheral surface of the stopper 23 that protrudes radially inward from the inner peripheral surface of the storage case 12 at the axial center portion of the storage case 12 . The bobbin 21 is fixed to the housing case 12 by being fastened between the fastening member 22 and the stopper 23.

  The bobbin 21 has a support inner peripheral surface 21 c that is in contact with the outer peripheral surface of the pipe 13 of the reciprocating rod 11 in the entire axial direction. The pipe 13 is inserted into the bobbin 21 and the reciprocating rod 11 is inserted into the bobbin 21. It is supported reciprocally. That is, the support inner peripheral surface 21c of the bobbin 21 and the outer peripheral surface of the pipe 13 are opposed to each other in a radial direction through a minute gap where the bobbin 21 and the pipe 13 are in sliding contact with each other. The bobbin 21 is integrally formed with a plurality of annular partition members 24 projecting radially outward from the outer peripheral surface. The plurality of partition members 24 are provided at substantially equal intervals in the axial direction of the bobbin 21, and a plurality of coil grooves are defined between the partition members 24 on the outer peripheral side of the bobbin 21.

  On the outer peripheral surface of the bobbin 21, a plurality of coils 25 are wound around the partition members 24, that is, coil grooves, so as to surround the magnet assembly 17 provided on the reciprocating rod 11. Each coil 25 is partitioned in the axial direction from each other by a partition member 24, and is wound around the bobbin 21 with the coil end surfaces of the coils 25 being abutted against each other via the partition member 24. A coil assembly 26 is formed in the coil housing hole 20 by arranging a plurality of cylindrical coils 25 formed in the axial direction so as to be approximately half the axial length of each permanent magnet 18. .

  Each coil 25 of the coil assembly 26 is electrically connected to a connector 27 provided in the housing case 12. By energizing each coil 25 through this connector 27, magnetic poles are formed in each coil 25 so that the coil end faces adjacent to each other have the same polarity. As a result, the magnetic flux concentrates in the radial direction in the vicinity of the coil end surfaces adjacent to each other of the coils 25, and a high magnetic flux density is generated in the radial direction. Then, by sequentially increasing / decreasing energization to each coil 25, the reciprocating rod 11 is moved from one end of the housing case 12 by the electromagnetic force between each permanent magnet 18 of the magnet assembly 17 and each coil 25 of the coil assembly 26. It protrudes and reciprocates in the axial direction.

  Each coil 25 of the coil assembly 26 is integrally resin-molded with a heat-dissipating resin material (heat-dissipating resin 28). The resin mold of each coil 25 is prepared by injecting molten heat-dissipating resin 28 into the coil housing hole 20 in a state where the bobbin 21 around which each coil 25 is wound is fixed in the coil housing hole 20. This is done by cooling and solidifying 28. Since the coils 25 are resin-molded with the heat-dissipating resin 28 in this manner, the heat generated in the coils 25 is easily transferred to the housing case 12 through the heat-dissipating resin 28, so that the heat dissipation of the coil 25 with respect to the heat generation is achieved. Has been improved.

  In the motor 10, the stroke of the reciprocating rod 11 is set in relation to the axial length of the magnet assembly 17 and the axial length of the coil assembly 26, and the magnet is moved when the reciprocating rod 11 reciprocates in the axial direction. The axial range where the assembly 17 and the coil assembly 26 face each other is the stroke of the reciprocating rod 11. That is, the stroke of the reciprocating rod 11 is set by the difference between the axial length of the magnet assembly 17 and the axial length of the coil assembly 26.

A guide hole 30 is formed on the inner peripheral surface of the housing case 12 so as to be positioned on the other end side of the coil housing hole 20 , and the guide hole 30 and the coil housing hole 20 are partitioned by a stopper 23. The diameter of the guide hole 30 is larger than the outer diameter of the annular member 15, and the annular member 15 reciprocates in the guide hole 30 as the reciprocating rod 11 reciprocates. The guide hole 30 is formed between a cover 31 that closes the other end of the housing case 12 and a stopper 23, and the axial length of the guide hole 30 is slightly longer than the stroke of the reciprocating rod 11. Is formed. That is, when the reciprocating rod 11 moves to the projecting limit position, one end surface of the annular member 15 is opposed to the stopper 23 with a predetermined gap. When the reciprocating rod 11 moves to the retreat limit position, the other end surface of the annular member 15 faces the cover 31 with a predetermined gap as shown in FIG.

By providing such a stopper structure, abnormal conditions such as when the energization of the coils 25 and when it is stopped, an abnormal load is or applied to the reciprocating rod 11 or the load is too large applied to the reciprocating rod 11 the time, the end face of the annular member 15 abuts against the stopper 23 or cover 31, to move in the axial direction of the reciprocating rod 11 is restricted. Therefore, in the above case, the reciprocating rod 11 is prevented from falling from the housing case 12, and the work driven by the reciprocating rod 11 is prevented from falling from the work table. In order to absorb an impact when the end surface of the annular member 15 is brought into contact with the stopper 23 or the cover 31, cushioning members such as rubber may be attached to both end surfaces of the annular member 15.

  In addition, a plurality of mounting holes are formed on the outer peripheral surface of the housing case 12, and the motor 10 is mounted on a conveying device (not shown) or the like by a screw member inserted into the mounting holes. Further, as shown in FIGS. 2 and 3, a sensor groove 12 a is formed on the outer peripheral surface of the housing case 12 along the axial direction of the housing case 12 to detect the position of the reciprocating rod 11. A sensor (not shown) can be attached to the sensor groove 12a. Further, a cable groove 12b is formed on the outer peripheral surface of the housing case 12 along the axial direction of the housing case 12, so that the cable 32 electrically connected to the connector 27 is inserted into the cable groove 12b. It has become.

  Next, a linear motor as a comparative example shown in FIG. 4 and the linear motor of the present invention will be compared and described. FIG. 4 is a sectional view showing a linear motor as a comparative example. In FIG. 4, the same members as those shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  In the motor 40 shown in FIG. 4, the coil assembly 26 is formed by winding a plurality of coils 25 around the outer peripheral surface of a bobbin 41 made of nonmagnetic metal such as stainless steel. The bobbin 41 has a thin cylindrical shape extending in the axial direction of the reciprocating rod 11, and the pipe 13 of the reciprocating rod 11 is inserted into the bobbin 41 so as to freely reciprocate. The inner peripheral surface of the bobbin 41 and the outer peripheral surface of the pipe 13 are opposed to each other in a radial direction via a predetermined gap 42 so that the bobbin 41 and the pipe 13 are not in sliding contact with each other. As a result, the seizure caused by the sliding contact between the bobbin 41 and the pipe 13 each formed of a metal material is prevented.

  The bobbin 41 is provided with a plurality of annular partition members 43 that extend radially outward from the outer peripheral surface of the bobbin 41. The plurality of resin partition members 43 are fixed by bonding or the like at substantially equal intervals in the axial direction of the bobbin 41, and a plurality of coil grooves are defined between the partition members 43 on the outer peripheral side of the bobbin 41. ing. On the outer peripheral surface of the bobbin 41, a plurality of coils 25 are wound around the partition members 43, that is, coil grooves, so as to surround the magnet assembly 17 provided on the reciprocating rod 11. Each coil 25 is partitioned in the axial direction from each other by a partition member 43, and is wound around the bobbin 41 with the coil end faces of each coil 25 abutting each other through the partition member 43. A coil assembly 26 is formed in the coil housing hole 20 by arranging a plurality of cylindrical coils 25 formed in the axial direction so as to be approximately half the axial length of each permanent magnet 18. .

  In addition, resin bearing members 44 a and 44 b are provided in the coil housing hole 20 so as to be positioned on the axially outer sides of both ends of the bobbin 41. The bearing members 44 a and 44 b are fitted to the inner peripheral surface of a cylindrical bearing housing 45 formed of a nonmagnetic metal material such as an aluminum alloy, and the bearing housings 45 are abutted against both ends of the bobbin 41. . The bearing housing 45 and the bobbin 41 are fixed to the housing case 12 by being fastened between the fastening member 22 and the stopper 23. Then, one end side of the reciprocating rod 11 (pipe 13) is supported by a bearing member 44a disposed on one end side of the bobbin 41 so as to freely reciprocate, and is reciprocated by a bearing 44b disposed on the other end side of the bobbin 41. The other end of the rod 11 (pipe 13) is supported so as to reciprocate.

  As described above, in the motor 40 as the comparative example shown in FIG. 4, the bobbin 41 is formed of a nonmagnetic metal material, so that seizure due to sliding contact between the metal material of the pipe 13 and the bobbin 41 is prevented. Therefore, it is necessary to provide a gap 42 of about 0.5 mm between the outer peripheral surface of the pipe 13 and the inner peripheral surface of the bobbin 41. On the other hand, in the motor 10 of the present invention, since the bobbin 21 is formed of a resin material, it is not necessary to provide a predetermined gap 42 between the pipe 13 and the bobbin 21. That is, there is no risk of seizure even if the metal pipe 13 and the resin bobbin 21 are brought into sliding contact, so that the outer peripheral surface of the pipe 13 and the support inner peripheral surface 21c of the bobbin 21 are in sliding contact. It is possible to support the pipe 13 so as to be able to reciprocate over the entire axial direction of the support inner peripheral surface 21c of the bobbin 21 by providing a small gap of about 0.05 mm. Therefore, the support inner peripheral surface 21c of the bobbin 21 is brought into contact with the outer peripheral surface of the pipe 13 as compared with the case where the predetermined gap 42 is provided between the pipe 13 and the bobbin 41 as in the motor 40 shown in FIG. Thus, the radial distance between the magnet assembly 17 and the coil assembly 26 can be reduced. Thereby, the electromagnetic force acting on the magnet assembly 17 and the coil assembly 26 is increased, and the thrust of the motor 10 can be improved.

  Further, by supporting the pipe 13 reciprocally by the bobbin 21, there is no need to provide bearing members 44a and 44b separately from the bobbin 41 as in the motor 40 shown in FIG. 4, and the number of parts of the motor 10 is reduced. be able to. Then, by reducing the number of parts of the motor 10, the structure of the motor 10 can be simplified and the cost can be reduced. Further, unlike the motor 40 shown in FIG. 4, it is not necessary to separately provide the bearing members 44 a and 44 b on the outer sides in the axial direction at both ends of the bobbin 41, so that the motor 10 can be reduced in size. That is, compared to the axial length L1 of the motor 40 shown in FIG. 4, it is possible to reduce the axial length L2 of the motor 10 by the amount that the bearing members 44a and 44b are not provided. Further, in order to support the outer peripheral surface of the pipe 13 in the entire axial direction of the support inner peripheral surface 21c of the bobbin 21, bearing members 44a and 44b are separately provided on the axially outer sides of both ends of the bobbin 41 as shown in FIG. The load applied to the reciprocating rod 11 can be dispersed and supported as compared with the case where the body is provided. Thereby, the wear of the support inner peripheral surface 21c of the bobbin 21 as a bearing member that supports the reciprocating rod 11 so as to freely reciprocate is reduced, and the maintenance frequency of the motor 10 can be suppressed.

  Further, since the bobbin 21 is formed of a resin material, it is possible to integrally form a resin partition member 24 for partitioning the coils 25 with the bobbin 21. Therefore, by forming the partition member 24 integrally with the bobbin 21, the number of parts of the motor 10 can be reduced as compared with the case where the partition member 43 is provided separately from the bobbin 41 as in the motor 40 shown in FIG. Can do. Then, by reducing the number of parts of the motor 10, the structure of the motor 10 can be simplified and the cost can be reduced.

  Further, since each coil 25 is resin-molded with the heat-dissipating resin 28, the heat-dissipating property with respect to the heat generation of the coil 25 can be improved. Therefore, compared to the case where the bobbin 41 is formed of a metal material as in the motor 40 shown in FIG. 4, when the bobbin 21 is formed of a resin material, the heat dissipation against the heat generation of the coil 25 is reduced. In addition, by resin molding each coil 25 with the heat-dissipating resin 28, it is possible to sufficiently ensure the heat-dissipating property against the heat generated by the coil 25.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, in the above embodiment, the bobbin 21 is fixed to the housing case 12 by tightening the bobbin 21 between the fastening member 22 and the stopper 23. However, the bobbin 21 is housed in the housing case 12 by another structure. You may make it fix to.

10 Motor (Linear motor)
DESCRIPTION OF SYMBOLS 11 Reciprocating rod 12 Housing | casing case 13 Pipe 18 Permanent magnet 21 Bobbin 21c Support inner peripheral surface 24 Partition member 25 Coil 28 Heat radiation resin

Claims (3)

A linear motor that reciprocates in the axial direction by projecting a reciprocating rod that is reciprocally attached to the housing case from the housing case,
A pipe made of a non-magnetic metal material that houses a plurality of permanent magnets in a state in which end faces of the same polarity are abutted against each other, a projecting shaft portion is provided at one end, and constitutes the reciprocating rod;
A pipe-shaped resin bobbin that is fixed to the housing case and that has a support inner peripheral surface that is in contact with the outer peripheral surface of the pipe and that is formed in the entire axial direction, and that supports the pipe over the entire support inner peripheral surface in a reciprocable manner; ,
A plurality of coils wound around the outer peripheral surface of the bobbin so as to surround each of the permanent magnets;
An annular member that is provided at the other end of the pipe and reciprocates in a guide hole formed in the housing case as the reciprocating rod reciprocates;
A screw shaft member that is screw-coupled to the inner peripheral surface of the annular member and presses the plurality of permanent magnets inserted into the pipe;
When the bobbin is fitted and supported by projecting radially inward from the inner peripheral surface of the housing case, and the reciprocating rod moves to the projecting limit position, one end surface of the annular member faces with a predetermined gap therebetween. And a stopper that abuts against the one end surface and restricts the movement of the reciprocating rod;
When the reciprocating rod is moved to the retreat limit position, the other end surface of the annular member is opposed to the other end surface with a predetermined distance when it is provided in the housing case and the reciprocating rod moves to the retreat limit position. And a cover for restricting movement of the reciprocating rod .   2. The linear motor according to claim 1, wherein a plurality of partition members for partitioning the plurality of coils are formed integrally with the bobbin.   3. The linear motor according to claim 1, wherein the plurality of coils are resin-molded with a heat-dissipating resin material.

Images