JP5691686B2 - Linear motor - Google Patents

Description

  The present invention relates to a linear motor in which a mover reciprocates.

  Patent Literature 1 discloses a linear actuator (linear motor) in which auxiliary yokes that transmit magnetic flux are provided on both end sides in the axial length direction of a permanent magnet on the mover side. According to this, the stator has a cylindrical excitation coil portion and a cylindrical outer yoke that covers the excitation coil portion. The reciprocating mover includes a cylindrical permanent magnet, a cylindrical inner yoke held on the inner peripheral side of the permanent magnet, and cylindrical auxiliary yokes provided at both ends in the axial length direction of the inner yoke. Have. Patent Document 2 discloses a reciprocating compressor including a linear motor having protrusions at both ends of an inner yoke. According to this linear motor, similarly to Patent Document 1, the stator has a cylindrical excitation coil portion and a cylindrical outer yoke that covers the excitation coil portion. The reciprocating mover has a cylindrical permanent magnet and a cylindrical inner yoke held on the inner peripheral side of the permanent magnet.

JP 2005-151750 A JP 2006-177338 A

  The current linear motor has a structure in which thrust is generated by the magnetic field bias generated by the magnetic field generated by the magnet and the magnetic field generated by the exciting coil unit. However, in this linear motor, the magnetic field formed by the exciting coil portion may not sufficiently permeate the interior of the permanent magnet, and may hardly permeate the yoke portion and contribute to the propulsive force. For this reason, there is room for improvement in improving the propulsive force that moves the mover along the axis.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a linear motor that is advantageous for increasing the thrust of a mover movable along the direction of the axis.

(1) A linear motor according to aspect 1 includes (i) a base portion having a bearing, and (ii) a ring-shaped excitation coil portion and an excitation coil portion provided around the axis and covering the axis. A stator having a ring-shaped outer yoke provided; and (iii) a shaft supported by a bearing so as to be reciprocally movable along a direction in which an axis is extended with respect to the stator, and an outer peripheral side of the shaft. The inner yoke formed of a yoke material having a ring shape around the axis and the inner circumferential surface of the outer yoke of the stator face each other through a minute gap and form a ring around the axis, and the outer circumferential surface and the inner circumferential surface And a mover having a permanent magnet having different magnetic poles,
(Iv) The outer yoke of the stator is
A ring-shaped outer outer yoke portion covering the outer peripheral side of the exciting coil portion, a shaft-shaped outer yoke portion covering each axial end of the exciting coil portion and connected to the outer peripheral outer yoke portion, and an exciting coil A first inner peripheral outer yoke portion and a second inner peripheral outer yoke portion facing each other, which are connected to the shaft end outer yoke portion so as to be positioned on the inner peripheral side of the first portion, and a first inner side of the exciting coil portion. An outer magnetoresistive portion that is provided between the inner peripheral outer yoke portion and the second inner peripheral outer yoke portion and has a ring shape around an axis that has a higher magnetic resistance than the yoke material;
(V) The inner yoke of the mover is
(V-1) a first inner circumference inner yoke portion and a second inner circumference inner yoke portion which form a ring shape facing each other on the inner circumference side of the permanent magnet and covering the inner circumference side of the permanent magnet; (v-2) A projecting yoke portion projecting radially outward from the shaft end of each of the first inner peripheral inner yoke portion and the second inner peripheral inner yoke portion so as to face the shaft end of the permanent magnet toward the stator; ) Provided on the inner circumference side of the permanent magnet, in the form of a ring having a higher magnetic resistance than the yoke material, and in the cross section passing through the axis along the axis, the magnetic flux is applied when the excitation current is applied to the excitation coil. A magnetic path that transmits the outer yoke portion and the inner yoke portion and reduces the magnetic flux that passes between the first inner peripheral inner yoke portion and the second inner peripheral inner yoke portion, and transmits the magnetic flux obliquely inside the permanent magnet. Formed Comprising an inner magnetic resistance portion that.

  When an alternating excitation current is applied to the excitation coil section, different magnetic poles are alternately generated at the shaft ends of the ring-shaped excitation coil section. A magnetic path through which the magnetic flux based on this passes through the inner yoke, the permanent magnet, and the outer yoke is formed, and the mover alternately reciprocates along the axis with respect to the stator by the magnetic path. When the exciting current is supplied to the exciting coil portion, the inner magnetoresistive portion forms a magnetic path through which the magnetic flux is transmitted obliquely inside the permanent magnet in a cross section passing through the axis along the axis.

  The vector of the magnetic path that passes in an oblique direction is composed of an axis perpendicular component that goes in a direction perpendicular to the axis and a thrust component that goes in a direction parallel to the axis. Here, if the magnetic path formed by the magnetic flux that passes through the interior of the permanent magnet in an oblique direction and enters the outer yoke is oriented obliquely (increases the inclination from the radial direction to the axial direction), the direction is parallel to the axial line. The thrust component of the mover can be increased. If the thrust component of the mover increases in this way, the thrust for reciprocating the mover along the axis can be increased.

  (2) In the linear motor according to aspect 2, in the above aspect, when the axial length of the permanent magnet is Lm and the axial length of the inner magnetoresistive portion is Li, Li <Lm. In this case, it is advantageous to increase the thrust component toward the direction parallel to the axis. If Li> Lm, there is a possibility of hindering the reciprocating movement of the mover.

  (3) According to the linear motor according to aspect 3, in the above aspect, when the axial length of the permanent magnet is Lm, the axial length of the inner magnetoresistive part is Li, and Li / Lm is α, α is It is set within the range of 0.10 to 0.63. As shown in FIG. 7 described later, it is advantageous to increase the efficiency and power factor of the linear motor.

  According to the present invention, the inner yoke of the mover is opposed to each other on the inner peripheral side of the permanent magnet, and forms a ring shape covering the inner peripheral side of the permanent magnet and the second inner peripheral inner yoke. A projecting yoke portion projecting radially outward from each shaft end of the first inner circumference inner yoke portion and the second inner circumference inner yoke portion so as to face the shaft end of the permanent magnet, And a magnetoresistive portion. The inner magnetoresistive portion is provided on the inner peripheral side of the permanent magnet and has a ring shape having a higher magnetic resistance than the yoke material. The inner magnetoresistive section transmits a magnetic flux to the outer yoke and the inner yoke and passes the first inner circumferential inner yoke section and the first inner yoke section when the exciting current is supplied to the exciting coil section in the cross section passing through the axis along the axis. (2) A magnetic path that reduces the magnetic flux transmitted between the inner peripheral inner yoke portion and transmits the magnetic flux in an oblique direction is formed inside the permanent magnet.

  According to the present invention in which such an inner magnetoresistive portion is formed, when the magnetic flux passes through the inner yoke, the permanent magnet, and the outer yoke, the interior of the permanent magnet is cross-sectionally taken along the axis along the axis. It is possible to increase the ratio of the magnetic flux transmitted in the oblique direction. For this reason, the thrust component of the needle | mover which goes to a direction parallel to an axis line increases. If the thrust component of the mover increases in this way, the thrust for reciprocating the mover along the axis increases.

It is sectional drawing of the linear motor which concerns on Embodiment 1 and was cut | disconnected along the axis line. FIG. 4 is a cross-sectional view of a mover mounted on a linear motor according to the first embodiment. FIG. 4 is a diagram schematically showing a magnetic path of magnetic flux that passes through the inner yoke, the permanent magnet, and the outer yoke according to the first embodiment. It is sectional drawing of a linear motor in connection with a comparison form. FIG. 6 is a cross-sectional view of a mover mounted on a linear motor according to the second embodiment. FIG. 10 is a cross-sectional view of a mover mounted on a linear motor according to the third embodiment. It is a figure which shows the dimensional relationship of Li, Lm, Lp, and All in connection with a test example. It is a graph which shows the relationship between Li / Lm, efficiency, and a power factor concerning a test example. It is sectional drawing of the linear motor which concerns on Embodiment 4 and makes a piston reciprocate. It is sectional drawing of the linear motor which concerns on Embodiment 5 and is mounted in the pulse tube refrigerator.

  The outer magnetoresistive portion formed on the outer yoke has a ring shape around the axis, and is provided between the first inner peripheral outer yoke portion and the second inner peripheral outer yoke portion on the inner peripheral side of the exciting coil portion. And has a higher magnetic resistance than the yoke material.

  The inner magnetoresistive portion formed in the inner yoke has a ring shape around the axis, is provided on the inner peripheral side of the permanent magnet, and has a higher magnetic resistance than the yoke material. The outer magnetoresistive portion and the inner magnetoresistive portion are formed of a material having a higher magnetic resistance than the air gap or the yoke material. The material having a high magnetic resistance can be formed of a nonmagnetic material (including a paramagnetic material). Examples of nonmagnetic materials include austenitic stainless steel, aluminum, aluminum alloys, and resins. Examples of the resin include known thermosetting resins and thermoplastic resins.

  The inner magnetoresistive portion is provided on the inner peripheral side of the permanent magnet and has a higher magnetic resistance than the yoke material. The inner magnetoresistive section transmits a magnetic flux through the outer yoke section and the inner yoke section in an oblique direction through the outer yoke section and the inner yoke section when an exciting current is passed through the exciting coil section in a cross section passing through the axis along the axis. A magnetic path is formed.

(Embodiment 1)
Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS. 1 and 2. 1 and 2 show a cross section passing through the axis P along the axis P. FIG. The linear motor 1 of this embodiment according to claim 1 includes a base 2, a stator 3, and a mover 4. The base 2 is a housing and has a drive chamber 20 and a bearing 21 called a flexure bearing disposed in the drive chamber 20. The stator 3 has an axis P and is fixed to the drive chamber 20 of the base 2. The stator 3 includes a ring-shaped excitation coil portion 30 provided around the axis P, and a ring-shaped outer yoke 32 that covers the excitation coil portion 30 and is provided around the axis P.

  The mover 4 is supported by the bearing 21 so as to be capable of reciprocating along the direction in which the axis P extends with respect to the stator 3. The axis P is along the horizontal direction, and the movable element 4 is moved along the horizontal direction. However, in some cases, the axis P may be along the vertical direction, and the movable element 4 may be moved along the vertical direction. In some cases, the axis P may be inclined along the vertical direction, and the movable element 4 may move along the diagonal direction with respect to the vertical direction.

  As shown in FIG. 1, the mover 4 includes a shaft 40 supported so as to be reciprocally movable along the axis P, an inner yoke 42 provided on the outer peripheral side of the shaft 40 and forming a ring shape around the axis P, A permanent magnet 45 having a magnetic pole facing the inner circumferential surface 32i of the outer yoke 32 of the stator 3 through a minute gap.

  The outer yoke 32 of the stator 3 is formed of a soft magnetic material having a high magnetic permeability, and each of the outer peripheral outer yoke portion 320 having a ring shape covering the outer peripheral surface 30p side of the exciting coil portion 30 and each of the exciting coil portions 30 is provided. A shaft end outer yoke portion 322 having a ring shape around the axis P covering the shaft ends 30e and 30f, and a shaft end outer yoke portion 322 connected to each other so as to be positioned on the inner peripheral surface 30i side of the exciting coil portion 30. It has the 1st inner peripheral outer yoke part 324 and the 2nd inner peripheral outer yoke part 325 which oppose. Further, as shown in FIG. 1, an outer magnetoresistive portion 328 formed by an air gap is provided on the inner peripheral surface 30 i side of the exciting coil portion 30. The outer magnetoresistive portion 328 has a higher magnetic resistance than the yoke material. As shown in FIG. 1, the outer magnetoresistive portion 328 has a ring shape around the axis P, and is provided between the first inner peripheral outer yoke portion 324 and the second inner peripheral outer yoke portion 325. The first inner peripheral outer yoke portion 324 and the second inner peripheral outer yoke portion 325 are separated in the axial length direction. The first inner peripheral outer yoke portion 324 and the second inner peripheral outer yoke portion 325 are integrally connected by the outer peripheral outer yoke portion 320.

  FIG. 2 shows the mover 4. As shown in FIG. 2, the inner yoke 42 of the mover 4 is made of a soft magnetic material having a high magnetic permeability, and is opposed to each other on the inner peripheral surface 45 i side of the permanent magnet 45 and the inner peripheral surface of the permanent magnet 45. The first inner peripheral inner yoke portion 421 and the second inner peripheral inner yoke portion 422 that form a ring shape covering the 45i side, and the inner peripheral inner yoke portions 421 and 422 so as to face the shaft ends 45e and 45f of the permanent magnet 45, respectively. A plurality of (two) projecting yoke portions 423 project in the radial direction (arrow D direction) from each shaft end toward the stator 3. The protruding yoke part 423 functions to reduce the magnetic resistance between the inner yoke 42 and the outer yoke 32. In this embodiment, the outer peripheral surface 45p side of the permanent magnet 45 is magnetized as an N pole, and the inner peripheral surface 45i side of the permanent magnet 45 is magnetized as an S pole. According to the present embodiment, the axial length Lm of the permanent magnet 45 is longer than the thickness t of the permanent magnet 45 (Lm> 2t).

  As shown in FIG. 2, the inner yoke 42 is fixed to the outer peripheral surface 40p side of the shaft 40 by an intermediate joint 48 formed of a resin (thermosetting resin or thermoplastic resin) having a higher magnetic resistance than the yoke material. Has been. An inner peripheral surface 42 i of the inner yoke 42 is integrally joined to the intermediate joint 48. In the inner yoke 42, an inner magnetoresistive portion 428 formed by an air gap having a ring shape around the axis P is provided on the inner peripheral surface 45 i side of the permanent magnet 45. Since the inner magnetoresistive portion 428 is formed of an air gap, it has a higher magnetic resistance than the yoke material. As shown in FIG. 1, an air gap 5 that functions as a third magnetoresistive portion is formed in a ring shape around the axis P between the shaft ends 45 e and 45 f of the permanent magnet 45 and the protruding yoke portion 423. And faces the outer yoke 32. The air gap 5 faces the shaft ends 45 e and 45 f of the permanent magnet 45 and suppresses the transmission of magnetic flux in the air gap 5.

  1 and 2 show a section through the axis P. In this cross section, the inner magnetoresistive portion 428 has a magnetic path through which the magnetic flux passes through the interior of the permanent magnet 45 in an oblique direction with respect to the outer peripheral surface 45p and the inner peripheral surface 45i when the exciting coil portion 30 is energized. Let it form. The outer magnetic resistance portion 328 and the inner magnetic resistance portion 428 are formed with an air gap. The air gap has a higher magnetic resistance than the yoke material. As shown in FIG. 2, the inner magnetoresistive portion 428 is partitioned in a ring shape around the axis P by the inner peripheral surface 45 i of the permanent magnet 45, the intermediate joint portion 48, and the inner peripheral inner yoke portions 421 and 422.

  The axis perpendicular line H shown in FIG. 1 is perpendicular to the axis P, and the axis of the axial length dimension of the permanent magnet 45 is set at the neutral position (the excitation coil section 30 is not energized). Pass in a perpendicular direction. The inner yoke 42, the outer yoke 32, the inner magnetoresistive portion 428, and the outer magnetoresistive portion 328 are preferably symmetrical with respect to the axis perpendicular line H. As shown in FIG. 2, the inner peripheral inner yoke portions 421 and 422 are formed with stepped engaging portions 429, and the inner periphery is formed by an adhesive with the permanent magnet 45 engaged with the engaging portion 429. The inner yoke portions 421 and 422 are fixed.

  When an exciting current of alternating current is passed through the exciting coil section 30, different magnetic poles (N pole, S pole) are alternately generated at one shaft end 30e and the other shaft end 30f of the exciting coil section 30. As a result, the movable element 4 reciprocates in the directions of the arrows X1 and X2 along the axis P with respect to the stator 3 repeatedly. Here, when the mover 4 moves forward in the direction of the arrow X1, one shaft end 30e of the exciting coil section 30 becomes the S pole, and the other shaft end 30f of the exciting coil section 30 becomes the N pole. When the mover 4 moves backward in the direction of the arrow X2, one shaft end 30e of the exciting coil section 30 becomes the N pole, and the other shaft end 30f becomes the S pole. In this way, the magnetic poles of the shaft ends 30e and 30f of the exciting coil unit 30 are alternately switched.

  FIG. 3 shows that the excitation coil 30 is energized to move the mover 4 in the arrow X1 direction when the excitation element 30 is not energized and the movable element 4 is in the neutral position. The basic state of the magnetic path analysis in the case of being made is shown schematically. As described above, in the inner yoke 42, the inner magnetoresistive portion 428 formed with an air gap having a high magnetic resistance around the axis P is provided on the inner peripheral surface 45 i side of the permanent magnet 45. . The inner magnetoresistive portion 428 separates the first inner peripheral inner yoke portion 421 and the second inner peripheral inner yoke portion 422 in the axial direction in a magnetic circuit manner. As a result, the magnetic flux passing through the first inner peripheral inner yoke portion 421 is suppressed from being transmitted directly to the second inner peripheral inner yoke portion 422 along the direction parallel to the axis P via the inner magnetoresistive portion 428. Yes. Similarly, direct transmission of the magnetic flux passing through the second inner peripheral inner yoke portion 422 to the first inner peripheral inner yoke portion 421 along the direction parallel to the axis P via the inner magnetic resistance portion 428 is suppressed. .

  According to this embodiment, the magnetic flux that passes through the inner yoke 42, the permanent magnet 45, and the outer yoke 32 along the radial direction (arrow D direction) is oriented along the direction perpendicular to the axis P. Rather than doing this, it becomes easier to orient in the direction along the axis P (direction along the direction parallel to the axis P).

  That is, when energizing the exciting coil unit 30 with the exciting current, the inner side of the permanent magnet 45 is axially aligned with respect to the inner peripheral surface 45p and the outer peripheral surface 45i along the direction parallel to the axis P of the permanent magnet 45. The ratio of the magnetic flux transmitted in the direction perpendicular to the axis of P is reduced. In other words, as shown in FIG. 3, according to the present embodiment, the magnetic flux portion φc (see FIG. 3) that is transmitted obliquely inside the cylindrical permanent magnet 45 with respect to the inner peripheral surface 45 p and the outer peripheral surface 45 i of the permanent magnet 45. The ratio of (see FIG. 3) increases. The diagonal means diagonal with respect to both the direction parallel to the axis P and the direction perpendicular to the axis.

  As described above, according to the present embodiment, the inner magnetoresistive portion 428 is provided in the inner yoke 42. Therefore, the magnetic flux portion φc (see FIG. 3) is transmitted in an oblique direction inside the permanent magnet 45 with respect to the inner peripheral surface 45p and the outer peripheral surface 45i of the permanent magnet 45 (relative to the direction in which the axis P extends). The ratio of orientation to becomes higher. In this case, the inner magnetoresistive portion 428 reduces the magnetic flux transmitted between the first inner peripheral inner yoke portion 421 and the second inner peripheral inner yoke portion 421 in the direction along the axis P.

  Here, the vector V of the magnetic flux portion φc that passes in an oblique direction is composed of an axis perpendicular component Vp that is perpendicular to the axis P and a thrust component Vh that is parallel to the axis P (see FIG. 3). ). In FIG. 3, the magnetic flux portion φc is schematically shown. Here, the inner peripheral surface 45p and the outer peripheral surface 45i of the permanent magnet 45 are along a direction parallel to the axis P. For this reason, if the rate at which the magnetic flux passes through the interior of the permanent magnet 45 in an oblique direction with respect to the inner circumferential surface 45p and the outer circumferential surface 45i of the permanent magnet 45 increases, the proportion of the magnetic flux oriented in the direction perpendicular to the axis increases. Compared to the comparative embodiment, the thrust component Vh that goes in the direction parallel to the axis P can be increased. When the thrust component Vh increases in this way, the mover propulsion driving force F that reciprocates the mover 4 along the axis P can be increased. Here, as the magnetic flux is oriented obliquely with respect to the inner peripheral surface 45p and the outer peripheral surface 45i of the permanent magnet 45, the thrust component Vh directed in the direction parallel to the axis P can be increased. When the thrust component Vh increases in this way, the mover propulsion driving force F that reciprocates the mover 4 along the axis P can be increased.

  Here, if the axial length Li along the axis P of the inner magnetoresistive portion 428 is increased, the inside of the permanent magnet 45 is transmitted in an oblique direction with respect to the inner peripheral surface 45p and the outer peripheral surface 45i of the permanent magnet 45. It is also conceivable that the ratio of the magnetic flux portion φc to be oriented increases. However, if the distance Li is increased, the transmission distance of the magnetic flux portion φc that obliquely passes through the permanent magnet 45 between the inner peripheral surface 45p and the outer peripheral surface 45i of the permanent magnet 45 becomes longer. May increase the magnetic resistance when transmitting between the inner peripheral surface 45p and the outer peripheral surface 45i, and the mover propulsion driving force F may decrease. Therefore, according to the present embodiment, as shown in FIGS. 1, 2, and 3, when the length along the axis P is the axial length, the permanent magnet 45 is in a state where the mover 4 exists in the neutral position. Is set to Lm, and the axial length of the inner magnetoresistive portion 428 is preferably set to Li <Lm. In this case, as a result of the magnetic simulation, it is advantageous to increase the thrust component directed in the direction parallel to the axis P.

  Here, as shown in FIG. 2, when the axial length of the inner magnetoresistive portion 428 is Li, the shortest distance between the two protruding yoke portions 423 is Lp, and the total axial length of the outer yoke 32 is Lall. , Lall> Lp> Lm> Li. This has been confirmed by a test conducted by the present inventors. The axial length L3 of the air grip 5 corresponds to (Lp−Lm) / 2.

  According to the present embodiment, as can be understood from FIG. 1, the ring-shaped exciting coil unit 30 is a single, and the ring-shaped permanent magnet 45 coaxially surrounded by the exciting coil unit 30 is also a single linear. It is intended for the motor 1, and a simple structure is sufficient.

  FIG. 4 shows a comparative form. Parts having the same function are denoted by the same reference numerals. In the comparative embodiment, the outer magnetoresistive portion 328 is formed with an air gap, but the inner magnetoresistive portion 428 is not formed. In the comparative embodiment, the inner magnetoresistive portion 428 is not formed, and the first inner peripheral inner yoke portion 421 and the second inner peripheral inner yoke portion 422 are integrally connected. For this reason, the ratio of the magnetic flux portion φw that continuously transmits through the first inner peripheral inner yoke portion 421 and the second inner peripheral inner yoke portion 422 along the axial length direction increases. As a result, the ratio of the magnetic flux portion φx that orients the interior of the permanent magnet 45 along the direction perpendicular to the axis rather than obliquely with respect to the axis P increases. In such a comparative form, unlike the present embodiment, a magnetic path that passes through the interior of the permanent magnet 45 in an oblique direction is difficult to be formed, and thus there is a limit in improving the thrust of the mover. The magnetic flux portions φw and φx are schematically illustrated.

(Embodiment 2)
FIG. 5 shows a second embodiment. The present embodiment has basically the same configuration and the same function and effect as the above-described embodiment. That is, the ratio of magnetic flux passing through the permanent magnet 45 in an oblique direction through the interior of the permanent magnet 45 with respect to the inner peripheral surface 45p and the outer peripheral surface 45i of the permanent magnet 45 increases. For this reason, the thrust component Vh which goes to the direction parallel to the axis line P can be increased compared with the comparative form with many ratios in which the magnetic flux is oriented in the direction perpendicular to the axis. As a result, the mover propulsion driving force F that reciprocates the mover 4 along the axis P can be increased.

  According to the present embodiment, as described above, the outer magnetoresistive portion 328 is formed of an air gap, but the inner magnetoresistive portion 428B is made of a resin material having a higher magnetic resistance than the yoke material and the intermediate joint portion 48. It is integrally formed. Examples of the resin material having a high magnetic resistance include known thermosetting resins and known thermoplastic resins. In the resin, an embedded substance such as a reinforcing fiber having a low magnetic permeability may be embedded. If the material of the inner magnetoresistive portion 428B is changed, the magnetic resistance of the inner magnetoresistive portion 428B can be adjusted, and adjustment of the orientation of the magnetic flux in the vicinity of the inner magnetoresistive portion 428B can be expected. As in the first embodiment, it is preferable that the relationship is All> Lp> Lm> Li.

(Embodiment 3)
FIG. 6 shows a third embodiment. The present embodiment has basically the same configuration and the same function and effect as the above-described embodiment. The inner magnetoresistive portion 428C is formed of a material having a higher magnetic resistance than the yoke material. The material having a high magnetic resistance can be formed of a nonmagnetic material (including a paramagnetic material) and includes metals such as austenitic stainless steel, aluminum, and an aluminum alloy. That is, the shaft 40 includes a shaft main body 400 and a flange portion 410 extending from the shaft main body 400 in the radially outward direction (arrow D direction). The flange portion 410 forms an inner magnetoresistive portion 428C, and magnetically separates the first inner peripheral inner yoke portion 421 and the second inner peripheral inner yoke portion 422 that form a ring shape. If the material of the inner magnetoresistive portion 428C is changed, the magnetic resistance can be adjusted, and adjustment of the orientation of the magnetic flux near the inner magnetoresistive portion 428C can be expected.

  Also in this embodiment, the flange portion 410 forms the inner magnetoresistive portion 428C, and the first inner peripheral inner yoke portion 421 and the second inner peripheral inner yoke portion 422 that form a ring shape are separated in the axial length direction. Therefore, as in the above-described embodiment, the inner magnetoresistive portion 428C transmits the interior of the permanent magnet 45 in an oblique direction with respect to the outer peripheral surface 45p and the inner peripheral surface 45i (direction parallel to the axis P). A magnetic path by magnetic flux can be formed. As described above, the vector of the magnetic flux passing in the oblique direction with respect to the direction parallel to the axis P includes an axis perpendicular component in a direction perpendicular to the axis P and a thrust component in a direction parallel to the axis P. Consists of. In this way, when the ratio of the magnetic flux that passes through the permanent magnet 45 in the oblique direction increases obliquely, the thrust component toward the direction parallel to the axis P increases. When the thrust component increases in this way, the thrust for reciprocating the mover 4 along the axis P increases. The more orienting obliquely, the more the thrust component that goes in the direction parallel to the axis P. If the thrust component increases in this way, the thrust for reciprocating the mover 4 along the axis P can be increased.

  According to the present embodiment, like the first embodiment, it is preferable that the relationship is All> Lp> Lm> Li. In this case, as a result of the magnetic simulation, it is advantageous to increase the thrust component directed in the direction parallel to the axis P.

(Test example)
7 and 8 show test examples tested by the inventors using magnetic simulation. In this case, when the axial length of the inner magnetoresistive portion 428 is Li, the shortest distance between the two protruding yoke portions 423 is Lp, and the total axial length of the outer yoke 32 is Lall, Lall>Lp>Lm> It is related to Li. Similarly, the relationship Li <Lm is established.

According to this test example, when Li / Lm is α (gap ratio) by magnetic simulation, changes in increase rate and power factor were tested while α was changed from 0 to 0.7. α = 0 means a state in which the inner magnetoresistive portion 428 does not exist. α = 0.7 means a state in which the axial length of the inner magnetoresistive portion 428 indicates 70% of the axial length of the permanent magnet 45. The test results are shown in FIG. In FIG. 8, ♦ indicates efficiency, and ■ indicates power factor. FIG. 8 shows the efficiency and power factor increase rate based on α (gap ratio) = 0 (the state in which there is no inner magnetoresistive portion 428). Here, efficiency and power factor are defined by the following equations.
Efficiency = Output / Active power output = F x v
Where F: thrust, v: velocity active power = VI cos θ
Where V: voltage (running value), I: current (running value), cos θ: power factor,
θ: Phase difference between voltage and current As can be understood from FIG. 8, as a result of the magnetic simulation, a mountain-shaped characteristic was obtained in which the efficiency increased as α increased, and the efficiency decreased as α increased further. . Moreover, the power factor increased as α increased, and a mountain-shaped characteristic was obtained in which the power factor decreased as α increased further. In consideration of increasing efficiency, α is preferably in the range of 0.10 to 0.63, more preferably in the range of 0.17 to 0.54, and still more preferably in the range of 0.22 to 0.42. . In consideration of increasing the power factor, α is preferably in the range of 0.10 to 0.54, and more preferably in the range of 0.17 to 0.54. It is preferable that the relationship is Lall>Lp>Lm> Li. About each embodiment which concerns on this invention, it is preferable that (alpha) is set to the above-mentioned range.

(Embodiment 4)
FIG. 9 shows Embodiment 4 of the present invention. The present embodiment has the same configuration as that of the first embodiment, and has the same function and effect. The base 2 holds a cylindrical cylinder 60 that partitions the compression chamber 61. A piston 62 that reciprocates in the compression chamber 61 along the axis P is held at the tip of the shaft 40. When an alternating exciting current is applied to the exciting coil unit 30, the mover 4 reciprocates repeatedly along the axis P in the directions of arrows X1 and X2. As a result, when the piston 62 moves forward in the direction of the arrow X1, the piston 62 performs a compression action and compresses the fluid in the compression chamber 61. When the piston 62 retreats in the direction of the arrow X2, the piston 62 performs a suction action and sucks the fluid into the compression chamber 61. Also in this embodiment, in consideration of increasing the efficiency and power factor of the linear motor 1, α is preferably set in the range of 0.10 to 0.63. It is preferable that the relationship is Lall>Lp>Lm> Li.

(Embodiment 5)
FIG. 10 shows Embodiment 5 of the present invention. The present embodiment has the same configuration as that of the first embodiment, and has the same function and effect. This embodiment is applied to a pulse tube refrigerator. The pulse tube refrigerator has a heat exchanger 70, a regenerator 71, a cold head 72, a pulse tube 73, a pulse tube high temperature end 74, and a buffer tank 75. A piston 62 that reciprocates in the compression chamber 61 is held at the tip of the shaft 40. When an alternating exciting current is applied to the exciting coil unit 30, the mover 4 reciprocates along the axis P in the directions of arrows X1 and X2 along with the piston 62 with a predetermined stroke. Here, when the piston 62 moves forward in the direction of the arrow X1, the piston 62 performs a compression action and compresses the gas refrigerant in the compression chamber 61. The compressed gas refrigerant flows through the heat exchanger 70, the regenerator 71, the cold head 72, the pulse tube 73, and the pulse tube high temperature end 74 in order, and reaches the buffer tank 75. On the other hand, when the piston 62 moves backward in the direction of the arrow X2, the piston 62 performs a suction action, and sucks the gas refrigerant into the compression chamber 61. In this case, the gas refrigerant is sucked into the compression chamber 61 via the buffer tank 75, the pulse tube high temperature end 74, the pulse tube 73, the cold head 72, the regenerator 71, and the heat exchanger 70. According to this embodiment, since the thrust of the piston 62 can be increased, if the fluid in the compression chamber 61 is effectively compressed, the fluid can be effectively sucked into the compression chamber 61. In this way, an oscillating flow or a reciprocating flow can be supplied to the outside. The fluid may be gas, liquid or mist.

  Also in the present embodiment, when Li / Lm is α, α is set in the range of 0.10 to 0.63 in consideration of increasing the efficiency and power factor of the linear motor 1. preferable. It is preferable that the relationship is Lall> Lp> Lm> Li.

(Other)
According to the above-described embodiment, the outer peripheral surface 45p side of the permanent magnet 45 is magnetized as an N pole, and the inner peripheral surface 45i side of the permanent magnet 45 is magnetized as an S pole. The outer peripheral surface 45p side of the magnet 45 may be magnetized as an S pole, and the inner peripheral surface 45i side of the permanent magnet 45 may be magnetized as an N pole. The present invention is not limited to the embodiments described above and shown in the drawings, and can be implemented with appropriate modifications within the scope not departing from the gist.

  1 is a linear motor, 2 is a base, 20 is a drive chamber, 21 is a bearing, 3 is a stator, 30 is an exciting coil part, 32 is an outer yoke, 320 is an outer peripheral outer yoke part, 322 is a shaft end outer yoke part, 328 Is an outer magnetoresistive portion, 4 is a mover, 40 is a shaft, 42 is an inner yoke, 421 is a first inner peripheral inner yoke portion, 422 is a second inner peripheral inner yoke portion, 428 is an inner magnetic resistance portion, and 45 is permanent. Magnet, 45p is an outer peripheral surface, 45i is an inner peripheral surface, 5 is an air gap, 60 is a cylinder, 61 is a compression chamber, 62 is a piston, 70 is a heat exchanger, 71 is a regenerator, 72 is a cold head, 73 is a pulse Reference numeral 74 denotes a pulse tube hot end, and reference numeral 75 denotes a buffer tank 75.

Claims (3)

A base with bearings;
A stator having a ring-shaped excitation coil portion provided on the base portion and provided around the axis; and an outer yoke formed of a ring-shaped yoke material that covers the excitation coil portion and that is provided around the axis. ,
The shaft is supported by the bearing so as to be reciprocally movable along the direction in which the axis extends with respect to the stator, and is formed of a yoke material provided on the outer peripheral side of the shaft and forming a ring shape around the axis. A mover having an inner yoke and an inner peripheral surface of the outer yoke of the stator that are opposed to each other through a minute gap and that has a ring shape around an axis and a permanent magnet having different magnetic poles on the outer peripheral surface and the inner peripheral surface. Has
The outer yoke of the stator is
A ring-shaped outer outer yoke portion covering the outer peripheral side of the exciting coil portion; and a shaft-shaped outer yoke portion covering the respective shaft ends of the exciting coil portion and connected to the outer peripheral outer yoke portion. A first inner periphery outer yoke portion and a second inner periphery outer yoke portion facing each other and connected to the shaft end outer yoke portion so as to be positioned on the inner periphery side of the excitation coil portion; and An outer magnetoresistive portion having a ring shape provided between the first inner peripheral outer yoke portion and the second inner peripheral outer yoke portion on the inner peripheral side and having a higher magnetic resistance than the yoke material;
The inner yoke of the mover is
A first inner circumference inner yoke portion and a second inner circumference inner yoke portion that form a ring shape that face each other on the inner circumference side of the permanent magnet and that covers the inner circumference side of the permanent magnet;
A projecting yoke portion projecting radially outward from each shaft end of the first inner circumferential inner yoke portion and the second inner circumferential inner yoke portion so as to face the shaft end of the permanent magnet;
A magnetic flux is provided when an excitation current is applied to the excitation coil section in a cross-section that is provided on the inner circumference side of the permanent magnet and has a ring shape having a magnetic resistance higher than that of the yoke material and passes through the axis along the axis. Is transmitted through the outer yoke and the inner yoke, and the magnetic flux transmitted between the first inner peripheral inner yoke portion and the second inner peripheral inner yoke portion is reduced, and transmitted in an oblique direction inside the permanent magnet. A linear motor comprising an inner magnetoresistive portion for forming a magnetic path to be formed.   2. The linear motor according to claim 1, wherein Li <Lm, where Lm is an axial length of the permanent magnet and Li is an axial length of the inner magnetoresistive portion.   In Claim 1, when the axial length of the permanent magnet is Lm, the axial length of the inner magnetoresistive portion is Li, and Li / Lm is α, α is in the range of 0.10 to 0.63. Linear motor set to.

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