JP2009077494A - Linear actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a downsized linear actuator which improves production efficiency, and efficiently and securely assembles a linear sensor, and. <P>SOLUTION: The linear actuator 11 is provided with: a moving member 13; and a stator 12 which is arranged in a periphery of the moving member 13 and has a plurality of coils 22 and 23 disposed to surround the moving member 13 on an inner side. The actuator 11 is also provided with: a sensor core part 35 whose magnetic resistance changes by relative displacement of the stator 12 and the moving member 13; and a sensor coil 36 for generating an AC magnetic field in the stator 12, the moving member 13 and a magnetic circuit formed of the sensor core part 35. The linear sensor 37 detecting a displacement amount of the moving member 13 is incorporated in the actuator. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a linear actuator.

Conventionally, a linear actuator that reciprocates a mover by electromagnetic action is known. Since this linear actuator can be driven by resonating with a spring, it is used as a compressor motor. Since the compressor using this linear actuator can exhibit excellent performance such as high efficiency, it is expected to be widely used in refrigerators, freezers or air conditioners.
Specifically, as the linear actuator, a stator formed in a cylindrical shape, a mover that is inserted into a cylindrical hole of the stator and supported so as to reciprocate, a coil that generates magnetomotive force, a cylinder, There is known a device including a permanent magnet disposed opposite to an inner wall of a hole with a mover interposed therebetween (see, for example, Patent Document 1).

When the coil is energized in the linear actuator having such a configuration, a magnetomotive force in a direction perpendicular to the axial direction of the mover is generated, and the magnetic flux is guided by the magnetic flux of the permanent magnet, and the magnetic flux density in the axial direction of the mover. Changes. Therefore, the mover can be moved in one of the axial directions, and the mover can be reciprocated by alternately changing the direction of the current flowing in the coil to alternately change the magnetic flux density in the axial direction. .
Further, a linear sensor is used to measure the displacement of the mover that reciprocates in this way. As a linear sensor, for example, a sensor that detects a relative displacement between a movable part and a detection part as an inductance change of a sensor coil is known (for example, see Patent Document 2).
JP 2004-343964 A JP 2006-208138 A

By the way, the above-described linear actuator and linear sensor have been designed and manufactured as separate products. Therefore, in order to measure the displacement of the mover, a linear sensor is generally assembled with a screw or the like outside or inside the linear actuator.
In such a conventional configuration, since the linear actuator and the linear sensor are separately manufactured in advance and then the linear sensor is incorporated into the linear actuator, the manufacturing and assembly are expensive and troublesome, and the improvement in production efficiency is limited. There was a problem that there was.
In recent years, linear actuators have been reduced in size, and such linear actuators have a problem that a space for incorporating a linear sensor becomes narrower and it is difficult to assemble with a screw.
Furthermore, in order to measure the displacement of the mover with the linear sensor, it is necessary to provide a separate mover for the linear sensor, which limits the miniaturization of the linear actuator.

  Therefore, the present invention has been made in view of the above circumstances, and provides a linear actuator that can improve production efficiency, can be assembled efficiently and reliably, and can be downsized. Is.

In order to solve the above-described problem, the invention described in claim 1 includes a mover and a plurality of coils arranged around the mover and arranged inside the mover so as to surround the mover. In a linear actuator including a stator, an AC magnetic field is applied to a sensor core portion in which a magnetic resistance is changed by relative displacement between the stator and the mover, and a magnetic circuit including the stator, the mover, and the sensor core portion. And a linear sensor capable of detecting the amount of displacement of the mover is incorporated.
According to the first aspect of the present invention, since the magnetic path for driving the linear actuator can be used as the magnetic path of the linear sensor, the linear actuator and the linear sensor can be reduced in size. In addition, since the linear sensor is assembled at the same time when the linear actuator is manufactured, the production efficiency can be improved.

The invention described in claim 2 is characterized in that an excitation current frequency of the sensor coil is higher than a driving frequency of the mover.
According to the second aspect of the present invention, the influence of driving the linear actuator can be reduced by separating the excitation current frequency of the sensor coil by a band pass filter or the like.

The invention described in claim 3 is characterized in that the linear sensor is connected to the stator.
According to the invention of claim 3, since the linear sensor can be assembled at the same time so as to be integrated with the stator of the linear actuator without using a screw or the like, the number of parts can be reduced. In other words, the linear sensor is assembled at the same time when the linear actuator is manufactured, so that the time required for the assembly can be shortened, and it can be manufactured without taking time and the production efficiency can be improved.

The invention described in claim 4 is characterized in that a plurality of the linear sensors are arranged in a direction along the axial direction of the mover.
According to the invention which concerns on Claim 4, the displacement amount of the highly accurate needle | mover which removed the noise component is detectable by taking the differential of the output value of a some linear sensor.

The invention described in claim 5 is characterized in that the linear sensors are respectively arranged at positions facing each other via the movable element.
According to the invention of claim 5, by taking the average of the output values of a plurality of linear sensors, the movable element can be used even when a disturbance occurs, for example, when the movable element vibrates in a direction other than the driving direction due to an external force. Can be detected with high accuracy.

The invention described in claim 6 is characterized in that a plurality of the linear sensors are arranged in a direction along the axial direction of the mover and are arranged at positions facing each other via the mover. .
According to the invention which concerns on Claim 6, the difference of the average of the output value of one linear sensor which opposes via a needle | mover, and the average of the output value of the other opposing linear sensor is taken, or an axial direction is taken. By taking the average of the differential of one linear sensor along the other and the differential of the other linear sensor, it is possible to perform measurement with high resistance to disturbance and high accuracy.

According to a seventh aspect of the present invention, a recess is formed in a direction along the circumferential direction of the mover on a protrusion that is formed to protrude from the stator at a position facing the peripheral surface of the mover. The sensor coil is wound around the peripheral surface of the protrusion.
According to the invention which concerns on Claim 7, since a linear sensor can be comprised using the level | step difference of the recessed part in a projection part, it becomes unnecessary to provide a sensor core part separately, and can reduce in size.

  According to the present invention, since the linear sensor is assembled at the same time when the linear actuator is manufactured, the production efficiency can be improved and the linear sensor can be reliably assembled. In addition, since the magnetic path for driving the linear actuator can be used as the magnetic path of the linear sensor, the linear actuator and the linear sensor can be reduced in size.

(First embodiment)
Next, a first embodiment of the present invention will be described with reference to FIGS.
A linear actuator 11 shown in FIGS. 1 to 4 includes a yoke 12 having a substantially rectangular outer shape as a stator, a mover 13 provided inside the yoke 12 so as to be capable of reciprocating along the axial direction, Permanent magnets 14 and 15 fixed on the inner left side and permanent magnets 16 and 17 fixed on the inner right side of the yoke 12 are provided.

  The permanent magnets 14 and 15 are attached to the tip surface 18 a of the magnetic path forming protrusion 18 provided inside the yoke 12 by an adhesive, and the permanent magnets 16 and 17 are formed as magnetic paths formed inside the yoke 12. The protrusion 19 is attached to the distal end surface 19a with an adhesive. These magnetic path forming projections 18 and 19 are provided with a predetermined width while being along the radial direction at opposite left and right positions of a through hole 21 provided in the axial direction in the central portion of the yoke 12. That is, as shown in FIG. 1 and FIG. 2, the magnetic path forming protrusion 18 protrudes from the left side surface 12 a on the inner side of the yoke 12 toward the mover 13, and its tip end surface 18 a is in contact with the peripheral surface of the mover 13. It is recessed in an arc shape to correspond. The magnetic path forming protrusion 19 protrudes from the inner right side surface 12 b of the yoke 12 toward the mover 13, and is recessed on an arc so that the tip surface 19 a corresponds to the peripheral surface of the mover 13.

  The permanent magnets 14 and 15 are made of ferrite magnets having the same diameter, the same length, and the same width, which are formed by cutting a cylinder in parallel at two locations at predetermined intervals, and are coaxial with each other, and are circular. They are aligned in the axial direction with their circumferential positions aligned. That is, the permanent magnets 14 are arranged on the left side and the permanent magnets 15 are arranged on the right side shown in FIG. These permanent magnets 14 and 15 have radial anisotropy in which magnetic poles are arranged in a direction orthogonal to the axial direction, and the arrangement of the magnetic poles is reversed. Specifically, the permanent magnet 14 has an N pole on the outer diameter side and an S pole on the inner diameter side, and the permanent magnet 15 has an N pole on the inner diameter side and an S pole on the outer diameter side. ing.

  The permanent magnets 16 and 17 are made of ferrite magnets that are formed in the same manner as the permanent magnets 14 and 15 and have the same diameter, the same length, and the same width. The permanent magnets 16 and 17 are coaxial with each other and aligned in the circumferential direction. They are lined up next to each other. That is, the permanent magnet 16 is arranged on the left side and the permanent magnet 17 is arranged on the right side shown in FIG. These permanent magnets 16 and 17 are also of a radial anisotropy in which magnetic poles are arranged in a direction orthogonal to the axial direction, and the arrangement of the magnetic poles is reversed. Specifically, the permanent magnet 16 has an N pole on the inner diameter side and an S pole on the outer diameter side, and the permanent magnet 17 has an N pole on the outer diameter side and an S pole on the inner diameter side. ing.

  As described above, the permanent magnet 14 and the permanent magnet 16 that are aligned in the penetrating direction of the through hole 21 have the magnetic poles on the inner diameter side opposite to each other, and the permanent magnet 15 and the permanent magnet 17 that are aligned in the axial direction of the through hole 21 are also included. The magnetic poles on the inner diameter side are opposite to each other.

The mover 13 has a cylindrical shape with a through-hole 20 formed in the center, and has an outer diameter slightly smaller than the inner diameter of the permanent magnets 14 to 17. The mover 13 is inserted between the magnetic path forming projections 18 and 19 of the yoke 12, that is, on the inner diameter side of the permanent magnets 14 to 17 so as to be coaxial with the permanent magnets 14 to 17. On the other hand, it is provided to be able to reciprocate in the penetration direction of the through hole 21. Therefore, there is a predetermined gap between the permanent magnets 14 and 15 and the permanent magnets 16 and 17 and the mover 13. The length of the mover 13 in the axial direction is shorter than the length of the yoke 12 in the through direction of the through hole 21.
The yoke 12 is formed by, for example, laminating a plurality of silicon steel plates in the axial direction, and the mover 13 is similarly formed of the same material.

  Further, as shown in FIG. 1, the coil 22 is wound so as to surround the magnetic path forming protrusion 18, and the coil 23 is wound so as to surround the magnetic path forming protrusion 19. Therefore, the yoke 12 is provided with magnetic path forming projections 18 and 19 and coils 22 and 23.

Here, FIG. 3 is a front sectional view at a position different from FIG.
As shown in FIG. 3, the yoke is divided into left and right parts when viewed from the front, and the divided yoke pieces 31, 32 are connected by connecting cores 33, 34, so that they are the same as the yoke 12 described above. The outer shape is substantially rectangular. The yoke piece 31 and the yoke piece 32 are formed in a symmetrical shape. Further, the yoke pieces 31 and 32 and the connecting cores 33 and 34 are formed of silicon steel plates in the same manner as the yoke 12.

  On the yoke piece 31 on the left side when viewed from the front, engaging convex portions 31b are formed at both circumferential end portions 31a facing the right yoke piece 32. Similarly, on the right yoke piece 32 in front view, engaging convex portions 32b are formed at both circumferential end portions 32a facing the left yoke piece 31. A connecting core 33 is provided for connecting the peripheral end portion 31 a of the upper yoke piece 31 and the peripheral end portion 32 a of the yoke piece 32 in a front view. The connecting core 33 is formed with engaging recesses 33a and 33b that engage with the engaging protrusions 31b of the yoke piece 31 and the engaging protrusions 32b of the yoke piece 32 at both ends.

  Similarly, a connecting core 34 for connecting the peripheral end portion 31a of the lower yoke piece 31 and the peripheral end portion 32a of the yoke piece 32 in the front view is provided. The connecting core 34 is formed with engaging recesses 34a and 34b that engage with the engaging protrusions 31b of the yoke piece 31 and the engaging protrusions 32b of the yoke piece 32 at both ends.

  The connecting core 34 is formed with a sensor core 35 projecting from the inner surface 34 c thereof toward the movable element 13. That is, the connecting core 34 and the sensor core 35 are formed in a T-shaped cross section when viewed from the front. As shown in FIG. 4, in a state where the yoke pieces 31 and 32 and the connecting cores 33 and 34 are connected, a plurality of layers are laminated in the direction along the axial direction of the mover 13, and the sensor core 35 is along the axial direction. It has a predetermined length (depth) in the direction. That is, the yoke in the present embodiment is composed of a region constituted by the yoke 12 described above and a region constituted by the yoke pieces 31 and 32 and the connecting cores 33 and 34. A gap d is formed between the tip of the sensor core 35 and the mover 13. The gap d can be made less susceptible to the influence of the surroundings if it is narrowed, but is adjusted to be appropriate in consideration of interference with other parts during assembly. In addition, the connection location of the yoke pieces 31 and 32 and the connecting cores 33 and 34 is integrated by welding. Further, a sensor coil 36 is wound around the sensor core 35.

  The sensor core 35 and the sensor coil 36 constitute a linear sensor 37. The linear sensor 37 can detect the displacement of the mover 13. Here, as shown in FIG. 4, any one end of the movable element 13 is configured so as to always overlap the sensor core 35 in a side view. That is, the displacement of the mover 13 can be detected by detecting the change in inductance of the sensor coil 36 caused by the overlap δ between the mover 13 and the sensor core 35 when the mover 13 reciprocates. ing.

(Function)
In the linear actuator 11 having the above structure, an alternating current is passed through the coils 22 and 23 on both sides in synchronization. Here, in FIGS. 5 to 8, by energizing both coils 22 and 23, a magnetic path in the direction of arrow a or b is formed, whereby the mover 13 is moved in the direction of arrow F shown in FIG. 8. Move forward and backward (reciprocate) in the direction of arrow G shown in FIG.

  Specifically, as shown in FIG. 5, in the linear actuator 11 having the above structure, when an alternating current (sine wave current, rectangular wave current) is passed through the coils 22 and 23, the magnetic flux is changed from the S pole to the N in the permanent magnet. By being guided to the pole, a magnetic flux loop a that circulates in the order of the outer periphery of the yoke piece 31, the permanent magnet 14, the mover 13, and the outer periphery of the yoke piece 32 is formed. As a result, a force acts on the mover 13 in the axial direction (F direction) shown in FIG. 6, and the mover 13 is pushed by the force and moves in the same direction. On the other hand, when a current in the direction opposite to the above direction flows through the coils 22 and 23, the magnetic flux is guided from the S pole to the N pole in the permanent magnet, so that the outer peripheral portion of the yoke piece 32, the permanent magnet 16, and the mover. 13 and the magnetic flux loop b which circulates in order of the outer peripheral part of the yoke piece 31 is formed. As a result, a force acts on the mover 13 in the axial direction (G direction) shown in FIG. 8, and the mover 13 is pushed by the force and moves in the same direction.

  The mover 13 repeats the above-described operation by alternately changing the direction of current flow to the coils 22 and 23 due to alternating current, and the mover 13 reciprocates in the axial direction with respect to the yoke 12. Become.

  On the other hand, as shown in FIG. 9, when an alternating current is passed through the sensor coil 36, the driving magnetic flux of the sensor is in the order of the sensor core 35, the mover 13, the permanent magnet 16 (permanent magnet 14), and the yoke piece 32 (yoke piece 31). A circulating magnetic flux loop c is formed. When the mover 13 moves in the F direction or the G direction, the overlap δ (see FIG. 4) between the sensor core 35 and the mover 13 changes, and the inductance of the sensor coil 36 changes. By detecting a change in inductance of the sensor coil 36, the relative displacement of the mover 13 with respect to the yoke 12 can be detected.

  According to the present embodiment, the movable element 13 and the yoke 12 having the plurality of coils 22 and 23 disposed around the movable element 13 and disposed around the movable element 13 are provided. In the linear actuator 11, a sensor core 35 whose magnetic resistance changes due to relative displacement between the yoke 12 and the mover 13, and a sensor coil 36 for generating an alternating magnetic field in a magnetic circuit composed of the yoke 12, the mover 13 and the sensor core 35. , And a linear sensor 37 capable of detecting the amount of displacement of the mover 13 is incorporated in a part of the yoke.

  Since it comprised in this way, the magnetic path for driving the linear actuator 11 can be utilized also as a magnetic path of the linear sensor 37, and the linear actuator 11 and the linear sensor 37 can be reduced in size. Moreover, since the linear sensor 37 is also assembled | attached simultaneously with manufacturing the linear actuator 11, production efficiency can be improved.

Further, the excitation current frequency of the sensor coil 36 is configured to be higher than the drive frequency of the mover 13.
Since it comprised in this way, the influence by driving the linear actuator 11 can be reduced by separating the exciting current frequency of the sensor coil 36 with a band pass filter or the like. Further, the excitation current of the sensor coil can be weak so as not to affect the driving of the linear actuator.

Further, the linear sensor 37 is configured to be connected to the yoke pieces 31 and 32.
Since it comprised in this way, the linear sensor 37 can be assembled | attached simultaneously so that it may integrate with the yoke 12 of the linear actuator 11 without using a screw etc., and a number of parts can be decreased. Therefore, the linear sensor 37 is assembled at the same time when the linear actuator 11 is manufactured, so that the time required for the assembly can be shortened, and it can be manufactured without taking time and the production efficiency can be improved.

Further, since the connecting core 34 and the sensor core 35 are integrated and formed into a T-shaped cross section, when the sensor coil 36 is wound around the sensor core 35 after that, the connecting core 34 becomes an engaging portion, and the coil can be easily wound. There is an effect that can be done. Furthermore, since the sensor core 35 is continuously formed on the yoke pieces 31 and 32 via the connecting core 34, the magnetic flux is not weakened and high-sensitivity measurement can be performed.
Furthermore, since the yoke pieces 31 and 32 and the connecting cores 33 and 34 are integrated by welding, the position of the linear sensor 37 provided integrally with the connecting core 34 is also fixed, and the displacement amount of the mover 13 is detected with high accuracy. can do.

(Second embodiment)
A second embodiment of the present invention will be described with reference to FIG. In addition, since this embodiment differs only in the installation form of a linear sensor from 1st embodiment, and other structures are substantially the same, the same code | symbol is attached | subjected to the same location and detailed description is abbreviate | omitted.
As shown in FIG. 10, two linear sensors are arranged side by side in the direction along the axial direction of the mover 13 in the linear actuator 111. The left linear sensor in FIG. 10 is a first linear sensor 137A, and the right linear sensor is a second linear sensor 137B. The first linear sensor 137A includes a first sensor core 135A and a first sensor coil 136A, and the second linear sensor 137B includes a second sensor core 135B and a second sensor coil 136B. In addition, about the assembly method of 1st linear sensor 137A and 2nd linear sensor 137B, it is the same as that of 1st embodiment.

(Function)
In the linear actuator 111 having the above structure, when an alternating current is passed through the coils 22 and 23 on both sides in synchronism, the mover 13 moves forward and backward (reciprocates) in the axial direction.
At this time, when an alternating current is passed through the first sensor coil 136A and the second sensor coil 136B, drive magnetic fluxes for the first linear sensor 137A and the second linear sensor 137B are formed, respectively. When the mover 13 moves in the axial direction, the overlap δ1 between the first sensor core 135A and the mover 13 changes, and the inductance of the first sensor coil 136A changes. At the same time, the overlap δ2 between the second sensor core 135B and the mover 13 changes, and the inductance of the second sensor coil 136B changes. For example, when the mover 13 moves in the + z direction (left direction) in FIG. 10, δ1 increases and δ2 decreases. Then, the inductance of the first sensor coil 136A increases and the inductance of the second sensor coil 136B decreases. Then, by taking a differential of the outputs of the first linear sensor 137A and the second linear sensor 137B, it is possible to perform highly accurate detection with the noise component removed.

According to the present embodiment, two linear sensors are arranged in the direction along the axial direction of the mover 13.
Since it comprised in this way, in addition to the effect of 1st embodiment, the highly accurate mover which removed the noise component by taking the differential of the output value of 1st linear sensor 137A and 2nd linear sensor 137B 13 displacement amounts can be detected.

(Third embodiment)
A third embodiment of the present invention will be described with reference to FIGS. In addition, since this embodiment differs only in the installation form of a linear sensor from 1st embodiment, and other structures are substantially the same, the same code | symbol is attached | subjected to the same location and detailed description is abbreviate | omitted.
As shown in FIGS. 11 and 12, two linear sensors are disposed in the linear actuator 211 at positions facing each other with the mover 13 therebetween. The lower linear sensor in FIG. 11 is a first linear sensor 237A, and the upper linear sensor is a second linear sensor 237B. The first linear sensor 237A includes a first sensor core 235A and a first sensor coil 236A, and the second linear sensor 237B includes a second sensor core 235B and a second sensor coil 236B. The method for assembling the first linear sensor 237A and the second linear sensor 237B is the same as in the first embodiment.

(Function)
In the linear actuator 211 having the above structure, when an alternating current is passed through the coils 22 and 23 on both sides in synchronism, the mover 13 moves forward and backward (reciprocates) in the axial direction.
At this time, when an alternating current is passed through the first sensor coil 236A and the second sensor coil 236B, drive magnetic fluxes for the first linear sensor 237A and the second linear sensor 237B are formed, respectively. When the mover 13 moves in the axial direction, the overlap δ1 between the first sensor core 235A and the mover 13 changes, and the inductance of the first sensor coil 236A changes. At the same time, the overlap δ2 between the second sensor core 235B and the mover 13 changes, and the inductance of the second sensor coil 236B changes. For example, when the mover 13 moves in the + z direction (left direction) in FIG. 12, both δ1 and δ2 increase. Then, both the inductance of the first sensor coil 236A and the inductance of the second sensor coil 236B increase. Then, by taking the average of the outputs of the first linear sensor 237A and the second linear sensor 237B, even when the movable element 13 vibrates in a direction (x, y direction) other than the driving direction due to an external force, it is resistant to disturbance. Output can be obtained.

According to the present embodiment, two linear sensors are arranged at positions facing each other with the mover 13 therebetween.
Since it comprised in this way, in addition to the effect of 1st embodiment, by taking the average of the output value of 1st linear sensor 237A and 2nd linear sensor 237B, for example, the needle | mover 13 is driving directions other than a driving direction by external force. The amount of displacement of the mover 13 can be detected with high accuracy even when a disturbance occurs, such as when it vibrates in the direction.

(Fourth embodiment)
A fourth embodiment of the present invention will be described with reference to FIG. In addition, since this embodiment differs only in the installation form of a linear sensor from 1st embodiment, and other structures are substantially the same, the same code | symbol is attached | subjected to the same location and detailed description is abbreviate | omitted.
As shown in FIG. 13, two linear sensors are arranged in the linear actuator 311 in a direction along the axial direction of the movable element 13, and two linear sensors are arranged at positions facing each other via the movable element 13. Has been placed. That is, in this embodiment, four linear sensors are arranged. In FIG. 13, the lower left linear sensor is the first linear sensor 337A, the right linear sensor is the second linear sensor 337B, the upper left linear sensor is the third linear sensor 337C, and the right linear sensor is the fourth linear sensor. Let it be sensor 337D.

  The first linear sensor 337A includes a first sensor core 335A and a first sensor coil 336A, and the second linear sensor 337B includes a second sensor core 335B and a second sensor coil 336B. 337C includes a third sensor core 335C and a third sensor coil 336C, and the fourth linear sensor 337D includes a fourth sensor core 335D and a fourth sensor coil 336D. In addition, about the assembly method of 1st linear sensor 337A-4th linear sensor 337D, it is the same as that of 1st embodiment.

(Function)
In the linear actuator 311 having the above structure, when an alternating current is passed through the coils 22 and 23 on both sides in synchronism, the mover 13 moves forward and backward (reciprocates) in the axial direction.
At this time, when an alternating current is passed through the first sensor coil 336A to the fourth sensor coil 336D, the driving magnetic fluxes of the first linear sensor 337A to the fourth linear sensor 337D are formed. When the mover 13 moves in the axial direction, the overlap δ1 between the first sensor core 335A and the mover 13 changes, and the inductance of the first sensor coil 336A changes. At the same time, the overlap δ2 between the second sensor core 335B and the mover 13 changes, and the inductance of the second sensor coil 336B changes. Furthermore, the overlap δ3 between the third sensor core 335C and the mover 13 changes, the inductance of the third sensor coil 336C changes, and the overlap δ4 between the fourth sensor core 335D and the mover 13 changes, resulting in the fourth sensor coil. The inductance of 336D changes.

  For example, in FIG. 13, when the mover 13 moves in the + z direction (left direction), δ1 and δ3 increase and δ2 and δ4 decrease. Then, the inductance of the first sensor coil 336A and the inductance of the third sensor coil 336C are increased, and the inductance of the second sensor coil 336B and the inductance of the fourth sensor coil 336D are decreased. Then, the difference between the output average of the first linear sensor 337A and the third linear sensor 337C and the output average of the second linear sensor 337B and the fourth linear sensor 337D is taken, or the first linear sensor 337A and the second linear sensor By taking the average of the differential output of the sensor 337B and the differential outputs of the third linear sensor 337C and the fourth linear sensor 337D, it is possible to perform measurement with high resistance to disturbance and high accuracy.

According to the present embodiment, two linear sensors are arranged in the direction along the axial direction of the movable element 13, and two linear sensors are arranged at positions facing each other via the movable element 13.
Since it comprised in this way, in addition to the effect of 1st embodiment, the average of the output value of 1st linear sensor 337A and 3rd linear sensor 337C which opposes via the needle | mover 13, and the other 2nd linear sensor which opposes the other 337B and the average of the output values of the fourth linear sensor 337D, or the differential of one of the first linear sensor 337A and the second linear sensor 337B along the axial direction and the other of the third linear sensor 337C By taking the average with the differential of the fourth linear sensor 337D, it is possible to perform measurement with high resistance to disturbance and high accuracy.

(Fifth embodiment)
A fifth embodiment of the present invention will be described with reference to FIG. In addition, since this embodiment differs only in the installation form of a linear sensor from 1st embodiment, and other structures are substantially the same, the same code | symbol is attached | subjected to the same location and detailed description is abbreviate | omitted.
As shown in FIG. 14, in the linear actuator 411, the permanent magnets 14 and 15 are attached to the tip surface of the magnetic path forming protrusion 18 provided inside the yoke 12 by an adhesive, and the permanent magnets 16 and 17 The magnetic path forming projection 19 provided on the inner side of the yoke 12 is attached to the front end surface of the yoke 12 with an adhesive.
Here, concave portions 450 are formed in the magnetic path forming protrusions 18 and 19 in the direction along the peripheral surface of the movable element 13. A sensor coil 436 is wound between the recess 450 and the outer peripheral surface of the magnetic path forming protrusion 19. With this configuration, the portion around which the sensor coil 436 is wound functions as the linear sensor 437.
In FIG. 14, the sensor coil 436 is wound only at one place. However, if the sensor coil 436 is wound at a plurality of places as in the second embodiment to the fourth embodiment, the second embodiment to the fourth embodiment. The same effect as the embodiment can be obtained.

According to the present embodiment, the recesses 450 are formed in the direction along the circumferential direction of the mover 13 on the magnetic path forming protrusions 18 and 19 that are formed to protrude from the stator 12 at positions facing the peripheral surface of the mover 13. The sensor coil 436 was wound between the recess 450 and the peripheral surfaces of the magnetic path forming protrusions 18 and 19.
Since it comprised in this way, the linear sensor 437 can be comprised using the level | step difference of the recessed part 450 in the magnetic path formation protrusions 18 and 19, it becomes unnecessary to provide a sensor core part separately, and it can reduce in size.

It should be noted that the technical scope of the present invention is not limited to the above-described embodiment, and includes those in which various modifications are made to the above-described embodiment without departing from the spirit of the present invention. That is, the specific materials, configurations, and the like given in the embodiment are merely examples, and can be changed as appropriate.
For example, in the present embodiment, the case where the linear sensor is integrated and arranged on the yoke (stator) side has been described. However, the linear sensor can be integrated and arranged on the movable element side. In this case, since the sensor coil is wound around the movable body, it may be energized in a non-contact manner, or may be energized by wiring a member that supports the movable element so as to reciprocate. Further, the linear sensor may be incorporated into the linear actuator by another locking method without being integrated with the yoke (stator) or the movable element.
Further, in the present embodiment, the case where one, two, and four linear sensors are arranged has been described, but three linear sensors may be arranged, and the number is not limited.
Furthermore, although the location where the linear sensor is arranged is constituted by the yoke piece and the connecting core, the yoke and the sensor core may be integrated by one member.
In this embodiment, the yoke is formed by stacking steel plates. However, the yoke is formed by a cylindrical member, and the linear sensor is not formed by stacking the steel plates. The sensor core and the sensor core may be integrated into a yoke made of a cylindrical member.

It is front sectional drawing of the linear actuator in embodiment of this invention. It is sectional drawing (plan sectional drawing) in alignment with the AA of FIG. It is front sectional drawing (sectional drawing in the position different from FIG. 1) of the linear actuator in 1st embodiment of this invention. It is sectional drawing (side sectional drawing) which follows the BB line of FIG. It is explanatory drawing which shows the direction of a magnetomotive force when a needle | mover reverse | retreats (-Z direction) in FIG. It is explanatory drawing seen from the side surface when a needle | mover retreats (F direction). It is explanatory drawing which shows the direction of a magnetomotive force when a needle | mover advances (+ Z direction) in FIG. It is explanatory drawing seen from the side surface when a needle | mover advances (G direction). It is explanatory drawing which shows the direction of the magnetomotive force of the linear sensor in FIG. It is side surface sectional drawing of the linear actuator in 2nd embodiment of this invention. It is front sectional drawing of the linear actuator in 3rd embodiment of this invention. It is sectional drawing (side sectional drawing) in alignment with the CC line of FIG. It is side surface sectional drawing of the linear actuator in 4th embodiment of this invention. It is a plane sectional view of a linear actuator in a fifth embodiment of the present invention.

Explanation of symbols

  11, 111, 211, 311 ... Linear actuator 12 ... Yoke (stator) 13 ... Movable member 18, 19 ... Magnetic path forming projection (projection) 22, 23 ... Coil 35, 135A, 135B, 235A, 235B, 335A, 335B, 335C, 335D ... sensor core (sensor core portion) 36, 136A, 136B, 236A, 236B, 336A, 336B, 336C, 336D, 436 ... sensor coil 37, 137A, 137B, 237A, 237B, 337A, 337B, 337C, 337D 437 Linear sensor 450 Recess

Claims (7)

A mover,
In a linear actuator provided with a stator having a plurality of coils arranged around the mover and disposed so as to surround the mover,
A sensor core part in which a magnetic resistance is changed by relative displacement between the stator and the mover; and a sensor coil for generating an alternating magnetic field in a magnetic circuit including the stator, the mover, and the sensor core part. A linear actuator incorporating a linear sensor capable of detecting a displacement amount of the mover.   The linear actuator according to claim 1, wherein an excitation current frequency of the sensor coil is higher than a driving frequency of the mover.   The linear actuator according to claim 1, wherein the linear sensor is connected to the stator.   The linear actuator according to any one of claims 1 to 3, wherein a plurality of the linear sensors are arranged in a direction along an axial direction of the mover.   The linear actuator according to any one of claims 1 to 3, wherein the linear sensors are respectively arranged at positions facing each other via the movable element.   4. The linear sensor according to claim 1, wherein a plurality of the linear sensors are arranged in a direction along an axial direction of the mover, and are arranged at positions facing each other through the mover. A linear actuator according to any one of the above.   A concave portion is formed in a protrusion along the circumferential direction of the movable element, and the concave portion is formed between the concave portion and the peripheral surface of the convex portion. The linear actuator according to claim 1, wherein the sensor coil is wound around the linear actuator.

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