JP6673579B2 - Actuator - Google Patents

Description

  The present invention relates to an actuator having a telescopic element such as a piezoelectric element and a displacement transmitting mechanism for transmitting a displacement of the telescopic element to another member.

  Actuators, which are mechanisms for "moving" something, are used in everything from industrial machinery, automobiles, aircraft, medical equipment, to the electrical appliances around us. The actuator is, for example, a solenoid or an air valve in an industrial mechanism, a moving mechanism for moving a magnetic chip for reading and writing to a hard disk drive in a personal computer, and a vibration motor generating vibration in a mobile phone. It is used as such.

  As an actuator, a piezoelectric actuator using a piezoelectric element has attracted attention as a driving element. The piezoelectric actuator (1) converts 60% or more of the applied electric energy into mechanical energy. For example, the force generated by an element having a cross section of 10 mm × 10 mm reaches 300 kgf, and the energy efficiency is extremely high. 2) High-speed response of several kHz or more is possible. (3) When an object is held at a fixed position, it is necessary to apply a voltage, but a current does not need to flow. (4) It is suitable for miniaturization and thinning.

  When a piezoelectric element is applied to an actual actuator or the like, it is often applied in a state of being mounted on a displacement transmission mechanism. For example, since the displacement of a piezoelectric element is as small as several μm to several tens of μm, a displacement enlargement mechanism that enlarges and transmits the displacement of the piezoelectric element is used as a displacement transmission mechanism (for example, Patent Document 1). Further, since a piezoelectric element is generally made of a ceramic material, it is brittle like ceramics, and is strong against compression but weak against tension. Therefore, when a piezoelectric element is used as an actuator, a compressive force is applied to the piezoelectric element as a displacement transmission mechanism in order to apply a compressive force of about １ ／ to ５〜 of a force generated from the piezoelectric element. A pressure mechanism is used (for example, Non-Patent Document 1).

  On the other hand, when a piezoelectric element is used for an actuator, a technique of attaching a strain gauge to the piezoelectric element for the purpose of detecting an abnormality in displacement of the piezoelectric element or correcting the displacement of the piezoelectric element is known (for example, Non-Patent Documents). 2).

JP 2004-48955 A

CEDRAT TECHNOLOGIES-PIEZO PRODUCTS CATALOGUE-Version 2.2-September 2001 Thorlabs Japan Co., Ltd. Product Information Actuator (Piezo Actuator PZS001), [Search on March 30, 2015], Internet <URL: http://www.thorlabs.co.jp/newgrouppage9.cfm?objectgroup_id=61>

  However, the technique of attaching a strain gauge to a piezoelectric element as described in Non-Patent Document 2 has the following disadvantages.

(1) Depending on the size of the piezoelectric element, the area or length may be too small to be stuck.
(2) Since the strain gauge is attached to the surface of the piezoelectric element, an operation of applying a bending stress to the piezoelectric element is performed, and the fragile piezoelectric element may be damaged.
(3) It is necessary to take out the wiring from the strain gauge.In this case, the lead is connected to the strain gauge with solder, but since the solder has no elasticity, it not only hinders the operation of the piezoelectric element but also reduces the stress at the connection part. Concentration leads to breakage of the piezoelectric element.
(4) In order not to hinder the driving of the piezoelectric element, the adhesive for attaching the strain gauge is also limited, and in particular, the hardness after curing is high, and the adhesive that can withstand a high temperature environment cannot be used. .
(5) In order to accurately measure distortion by compensating for the amount of distortion due to temperature effects due to changes in environmental temperature, it is necessary to use a strain gauge with a thermal expansion coefficient that matches the thermal expansion coefficient of the mating target However, since there is no strain gauge having a thermal expansion coefficient corresponding to a piezoelectric element having a negative thermal expansion coefficient, it is difficult to perform accurate measurement excluding the influence of temperature.
(6) The internal and external electrodes of the piezoelectric element are exposed on the surface of the piezoelectric element. When a strain gauge is adhered to a piezoelectric element, coupling by electrostatic induction via an insulating film is inevitable even if electrical insulation is provided. Therefore, the piezoelectric element drive voltage generates an induced electromotive force in the strain gauge, and causes an error in the reading of the strain gauge.
(7) There is always a film on the surface of the piezoelectric element, and when the strain gauge is directly attached to the piezoelectric element, it must be attached to the film on the surface of the piezoelectric element and attached to the piezoelectric element itself. I can't. Therefore, in the case of high-speed operation, slippage occurs between the piezoelectric element and the film, and the true displacement and distortion amount of the piezoelectric element are not 1: 1 and it is difficult to cope with high-speed driving.

  Further, there is a case where an abnormality of the actuator cannot be detected simply by attaching a strain gauge to the surface of the piezoelectric element and detecting the strain.

  The present invention has been made in view of such a point, and provides an actuator capable of sufficiently detecting an abnormality without inconvenience when directly attaching a strain gauge to a telescopic element such as a piezoelectric element. That is the task.

In order to solve the above problems, the present invention provides the following (1) to ( 3 ).

(1) a telescopic element that expands and contracts in a predetermined direction;
A displacement transmission mechanism to which the telescopic element is mounted and transmits the telescopic displacement of the telescopic element to a moving object,
In the displacement transmission mechanism, a strain gauge provided at a position where a strain due to the displacement of the expansion element is generated,
A drive unit that expands and contracts the expandable element,
While correcting the expansion and contraction of the telescopic element based on the detected value of the strain gauge, grasping the abnormality of the telescopic element or the displacement transmission mechanism based on the detected value of the strain gauge,
The displacement transmission mechanism,
A pair of head pieces fixed to one end face and the other end face of the expansion element in the direction of expansion and contraction, and a linear compression force applied integrally with the head piece and provided so as to be bridged between the head pieces; Having a pressurizing mechanism for applying a compressive force in the direction of expansion and contraction of the expansion and contraction element,
A portion between the pair of head pieces of the compressive force applying portion forms one straight line, and the portion forming the one straight line is distorted in the direction of the one straight line corresponding to the direction of expansion and contraction of the expansion and contraction element,
The actuator according to claim 1, wherein the strain gauge is provided at a portion of the compression force applying unit that forms the one straight line .

(2) The driving unit includes a driver that supplies a driving signal to the expansion / contraction element, and a control unit that controls the driver.
The control unit, based on the detected value of the strain gauge, and corrects the input target position, when the detected value of the strain gauge indicates an abnormality of the telescopic element or the displacement transmission mechanism, The actuator according to (1), wherein the driver is stopped or an alarm is issued.

( 3 ) The actuator according to (1) or (2) , wherein the elastic element is any one of a piezoelectric element, a magnetostrictive element, and a shape memory alloy element.

  According to the present invention, since the strain gauge is provided in the displacement transmission mechanism, no inconvenience occurs when the strain gauge is directly attached to the expansion element. Further, not only when there is an abnormality in the expansion / contraction element, but also an abnormality in the displacement transmission mechanism can be detected, and an abnormality in the actuator can be sufficiently detected.

FIG. 2 is a front view illustrating the actuator according to the first embodiment of the present invention. It is a front view showing the actuator concerning a 2nd embodiment of the present invention. It is a front view showing other positions suitable for providing a strain gauge in an actuator concerning a 2nd embodiment of the present invention. It is a front view showing the actuator concerning a 3rd embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail.
<First embodiment>
FIG. 1 is a front view showing the actuator according to the first embodiment of the present invention.
As shown in FIG. 1, the actuator 100 includes a telescopic element 1 that expands and contracts in a predetermined direction, a displacement magnifying mechanism 2 that transmits a displacement of the telescopic element 1, and a strain gauge attached to the displacement magnifying mechanism 2. 3 and a drive unit 4 for driving the expansion / contraction element 1.

The expansion / contraction element 1 is configured as a rectangular parallelepiped piezoelectric element having a length of, for example, 40 mm, in which a plurality of 10 mm × 10 mm plate-shaped piezoelectric bodies are laminated with electrodes interposed therebetween. The piezoelectric element constituting the elastic element 1 has an electric terminal (not shown) for applying a voltage to a side surface, and when a voltage is applied between the electric terminals, the piezoelectric element is indicated by an arrow A in FIG. It is configured to expand and contract in the length direction (Y direction in FIG. 1). As the piezoelectric material constituting the piezoelectric body, a ceramic material having a piezoelectric effect is used. As such a material, typically, lead zirconate titanate (Pb (Zr, Ti) O ₃ ; PZT) is given. Can be. The shape of the expansion element 1 is not limited to a rectangular parallelepiped, and may be, for example, a polygonal column such as a triangular column or a hexagonal column, or a column. The expansion element 1 is not limited to a piezoelectric element, but may be any element that expands and contracts in a predetermined direction, such as a magnetostrictive element that changes according to a magnetic field, a shape memory alloy element that changes according to temperature, and the like. When these are used, the displacement according to the voltage can be realized by converting the voltage into a magnetic field or a temperature by an appropriate means.

  The expansion element 1 is applied with a compression force in advance by an appropriate method in a state where the expansion element 1 is mounted on the displacement enlarging mechanism. In particular, when a piezoelectric element is used as the expansion / contraction element, it is important to apply a compressive force in advance because the piezoelectric element is made of a brittle ceramic material and is weak against a tensile force. Examples of the method of applying a compressive force to the expansion element in advance include the methods described in JP-A-2008-99399 and JP-A-2012-139028.

  The displacement enlarging mechanism 2 is configured as a hinge mechanism having a flexible hinge, receives the displacement of the telescopic element 1 in the Y direction, outputs the enlarged displacement in the X direction, and outputs the enlarged displacement. It is transmitted to a movement target member (not shown), and is provided so as to cover the outside of the expandable element 1. The displacement enlarging mechanism 2 has a first headpiece 11 and a second headpiece 12 fixed to one end face and the other end face in the length direction (Y direction) of the expansion and contraction element 1, respectively. A first displacement transmitting portion 10a and a second displacement transmitting portion 10b are provided on one side and the other side of the telescopic element 1 between the second head pieces 12, respectively.

  The first displacement transmitting unit 10a includes a first hinge 13a, a first intermediate member 14a, a second hinge 15a, a first output member 16a, a third hinge 17a, a second intermediate member 18a, and a fourth hinge. 19a, the first intermediate member 14a is connected to the first headpiece 11 via the first hinge 13a, and the second intermediate member 18a is connected to the second headpiece 12 via the fourth hinge 19a. The first output member 16a is connected to the first intermediate member 14a and the second intermediate member 18a via the second hinge 15a and the third hinge 17a, respectively. The outer surfaces of the first hinge 13a, the first intermediate member 14a, the second hinge 15a, the first output member 16a, the third hinge 17a, the second intermediate member 18a, and the fourth hinge 19a are the same. It is a plane. Thereby, the strain gauge 3 is easily formed.

  On the other hand, the second displacement transmitting unit 10b includes a fifth hinge 13b, a third intermediate member 14b, a sixth hinge 15b, a second output member 16b, a seventh hinge 17b, a fourth intermediate member 18b, 8th hinge 19b, the third intermediate member 14b is connected to the first headpiece 11 via the fifth hinge 13b, and the fourth intermediate member 18b is connected to the second headpiece 12 via the eighth hinge 19b. The second output member 16b is connected to the third intermediate member 14b and the fourth intermediate member 18b via the sixth hinge 15b and the seventh hinge 17b, respectively. The outer surfaces of the fifth hinge 13b, the third intermediate member 14b, the sixth hinge 15b, the second output member 16b, the seventh hinge 17b, the fourth intermediate member 18b, and the eighth hinge 19b are also flush. It has become.

  The first output member 16a and the second output member 16b are provided at the center in the length direction (Y direction) of the expansion and contraction element 1 so as to face the expansion and contraction element 1 therebetween. A movement target member (not shown) is attached to the first output member 16a. On the other hand, the second output member 16b is fixed to the fixing jig 9.

  The first intermediate member 14a and the second intermediate member 18a are symmetrically arranged with the first output member 16a interposed therebetween, and the first intermediate member 14a and the second intermediate member 18a, and the third intermediate member 14b and the fourth intermediate member 18b Is symmetrically arranged with respect to the elastic element 1. Further, the first to eighth hinges 13a, 15a, 17a, 19a, 13b, 15b, 17b, 19b have flexibility and bend by the expansion and contraction of the expandable element 1 to change the displacement of the expandable element 1 to the first output member 16a. And the second output member 16b, and the expanded displacement in the X direction is output from the first output member 16a and the second output member 16b by the expansion and contraction displacement of the expandable element 1 in the Y direction. It has become.

  The first hinge 13a, the fourth hinge 19a, the fifth hinge 13b, and the eighth hinge 19b are provided outside the second hinge 15a, the third hinge 17a, the sixth hinge 15b, and the seventh hinge 17b. Therefore, when the extendable element 1 is extended, the first output member 16a and the second output member 16b are displaced outward relative to the extendable element 1. At this time, since the second output member 16b is fixed by the fixing jig 9, the second output member 16b is actually a stationary part. For this reason, when the telescopic element 1 is extended, portions other than the second output member 16b are displaced together with the telescopic element in the direction of arrow B in FIG. 1, and the displacement is transmitted to the movement target member.

  Instead of attaching the movement target member to the first output member 16a and fixing the second output member 16b, the movement target member may be attached to the second output member 16b to fix the first output member 16a. Then, the movement target member may be attached to both the first output member 16a and the second output member 16b, and both may be operated.

  In this way, the expansion and contraction displacement of the expansion and contraction element 1 in the Y direction is transmitted to the displacement enlarging mechanism 2, and can be enlarged to about 10 to 30 times and transmitted to the movement target member as the displacement in the X direction.

  The strain gauge 3 generally utilizes a phenomenon in which the electric resistance of a thin wire or foil-shaped gauge material changes due to elastic strain, and detects the distortion by measuring the change in the electric resistance. A metal foil such as CuNi or NiCr is formed as a strain sensor. The resin substrate may be attached to the displacement enlarging mechanism 2 using an adhesive, or may be formed on the displacement enlarging mechanism 2 by thick film printing or vapor deposition.

  The strain gauge 3 detects a strain of the displacement magnifying mechanism 2 which is a displacement transmitting mechanism. Since the displacement magnifying mechanism 2 transmits the displacement of the elastic element 1, the strain detected by the strain gauge 3 corresponds to the displacement of the elastic element 1.

  The strain gauge 3 may be provided at a portion where distortion occurs due to the expansion and contraction displacement of the expansion and contraction element 1, but is preferably provided at a portion where the distortion is large, for example, at a portion corresponding to a hinge or in the vicinity thereof. Due to the large distortion, good sensitivity can be obtained. In the example of FIG. 1, an example is shown in which a portion (front surface) corresponding to the first hinge 13a is provided, but a portion corresponding to the second to eighth hinges 15a, 17a, 19a, 13b, 15b, 17b, 19b is provided. There may be. Further, a plurality of strain gauges 3 may be provided.

  The driving unit 4 applies a voltage to the expansion / contraction element 1 to drive the expansion / contraction element 1, a control unit 42 for controlling the driving of the expansion / contraction element 1, and issues an alarm when there is an abnormality. An alarm 43 is provided.

  The control unit 42 receives a target position from a setting device or the like, and outputs a control signal to the driver 41 based on the target position. The driver 41 applies a predetermined voltage to the expandable element 1 based on the control signal to expand and contract the expandable element 1. Let it.

  Further, the detection value of the strain gauge 3 is input to the control unit 42, and if the displacement or position of the extensible element 1 calculated from the detected value is deviated from the target, the target position is corrected based on the displacement or position. The corrected control signal is output to the driver 41. Further, when there is an abnormality in the telescopic displacement 1 such as when the telescopic element 1 has been excessively displaced or when the telescopic element 1 does not undergo telescopic displacement due to a short circuit or the like, a signal is sent to the alarm 43 to give an alarm (alarm). Or a stop signal is output to the driver 41.

  Also, when there is an abnormality in the displacement magnifying mechanism 2 such as a large external force applied to the displacement magnifying mechanism 2 itself, a signal is sent to the alarm 43 to generate an alarm (alarm), or a stop signal is output to the driver 41. And take other measures.

  In the actuator 100 configured as described above, when the driver 41 applies a predetermined voltage to the expandable element 1 based on a command from the control unit 42 of the drive unit 4, the expandable element 1 expands and displaces in the Y direction. At the same time, the displacement is transmitted to the displacement magnifying mechanism 2, which is a displacement transmitting mechanism. In the displacement magnifying mechanism 2, the extension displacement of the telescopic element 1 is transmitted to the first headpiece 11 and the second headpiece 12, and the first to fourth hinges 13a, 15a, 17a, 19a of the first displacement transmission unit 10a and The first output member 16a and the second output member 16b are displaced outward along the X direction as shown by the arrow B via the fifth to eighth hinges 13b, 15b, 17b, 19b of the second displacement transmission section 10b. Then, the displacement is output as a displacement in the X direction that is enlarged about 10 to 30 times. Then, the enlarged displacement is transmitted to a movement target member (not shown). When the elastic element 1 is retracted from the expanded state, the first output member 16a and the second output member 16b are displaced inward by the reverse operation.

  As described above, when the movement target member is moved using the actuator 100, the strain gauge 3 detects the strain of the displacement magnifying mechanism 2 as the displacement transmission mechanism. At this time, the strain of the displacement magnifying mechanism 2 itself is detected by the strain gauge 3, and this reflects the strain caused by the expansion and contraction of the expansion element 1. Therefore, when the displacement or the position of the elastic element 1 calculated from the detected value of the strain gauge 3 is deviated from the target, the target position sent to the control unit 42 based on the detection signal from the strain gauge 3 is determined. The corrected control signal is output to the driver 41 based on the correction, and the displacement of the telescopic element 1 can be corrected. Further, when there is an abnormality in the elastic element 1 such as when the elastic element 1 is excessively displaced or when the elastic element 1 does not expand or contract due to a short circuit or the like, a signal is sent to the alarm 43 to give an alarm (alarm). Or a measure such as outputting a stop signal to the driver 41 can be used to prevent the expansion element 1 from being destroyed.

  Conventionally, a strain gauge has been attached to the piezoelectric element for the purpose of detecting an abnormality in displacement of the piezoelectric element, which is a telescopic element, or correcting the displacement of the piezoelectric element (Non-Patent Document 2). However, there were the following inconveniences.

(1) Depending on the size of the piezoelectric element, the area or length may be too small to be stuck.
(2) Since the strain gauge is attached to the surface of the piezoelectric element, an operation of applying a bending stress to the piezoelectric element is performed, and the fragile piezoelectric element may be damaged.
(3) It is necessary to take out the wiring from the strain gauge.In this case, the lead is connected to the strain gauge with solder, but since the solder has no elasticity, it not only hinders the operation of the piezoelectric element but also reduces the stress at the connection part. Concentration leads to breakage of the piezoelectric element.
(4) In order not to hinder the driving of the piezoelectric element, the adhesive for attaching the strain gauge is also limited, and in particular, the hardness after curing is high, and the adhesive that can withstand a high temperature environment cannot be used. .
(5) In order to accurately measure distortion by compensating for the amount of distortion due to temperature effects due to changes in environmental temperature, it is necessary to use a strain gauge with a thermal expansion coefficient that matches the thermal expansion coefficient of the mating target However, since there is no strain gauge having a thermal expansion coefficient corresponding to a piezoelectric element having a negative thermal expansion coefficient, it is difficult to perform accurate measurement excluding the influence of temperature.
(6) The internal and external electrodes of the piezoelectric element are exposed on the surface of the piezoelectric element. When a strain gauge is adhered to a piezoelectric element, coupling by electrostatic induction via an insulating film is inevitable even if electrical insulation is provided. Therefore, the piezoelectric element drive voltage generates an induced electromotive force in the strain gauge, and causes an error in the reading of the strain gauge.
(7) There is always a film on the surface of the piezoelectric element, and when the strain gauge is directly attached to the piezoelectric element, it must be attached to the film on the surface of the piezoelectric element and attached to the piezoelectric element itself. I can't. Therefore, in the case of high-speed operation, slippage occurs between the piezoelectric element and the film, and the true displacement and distortion amount of the piezoelectric element are not 1: 1 and it is difficult to cope with high-speed driving.

  On the other hand, by providing the strain gauge 3 in the displacement magnifying mechanism 2, which is a displacement transmitting mechanism, it is possible to detect an abnormality in the displacement of the telescopic element without causing the inconveniences (1) to (7) above, The displacement of the expansion element can be corrected.

  Further, if a strain is simply detected by attaching a strain gauge to the surface of the expansion / contraction element, if an abnormality occurs in the displacement magnifying mechanism 2 such as when an external force is applied to the displacement magnifying mechanism 2 which is a displacement transmitting mechanism, However, the provision of the strain gauge 3 in the displacement magnifying mechanism 2 makes it possible to reliably detect an abnormality of the displacement magnifying mechanism 2. Specifically, the displacement magnifying mechanism 2 serving as the displacement transmitting mechanism can be prevented from being destroyed, and even if the displacement magnifying mechanism 2 serving as the displacement transmitting mechanism is displaced by an external force, it is detected. Thus, the position of the displacement enlarging mechanism 2 can be returned.

  Further, by providing the strain gauge 3 at the hinge portion of the displacement magnifying mechanism 2 or in the vicinity thereof, a large displacement can be detected, and more accurate strain detection can be performed.

<Second embodiment>
FIG. 2 is a front view showing an actuator according to a second embodiment of the present invention.
In the present embodiment, an example in which another type of displacement enlarging mechanism 2 'different from that of the first embodiment is provided as a displacement transmitting mechanism will be described.

  As shown in FIG. 2, the actuator 101 includes a telescopic element 1, a displacement magnifying mechanism 2 'as a displacement transmission mechanism, a strain gauge 3 mounted on the displacement magnifying mechanism 2', and a driving unit for driving the telescopic element 1. And 4. The configurations of the expansion element 1, the strain gauge 3, and the driving unit 4 are the same as those of the first embodiment, and thus the description is omitted.

  The displacement magnifying mechanism 2 ′, which is a displacement transmitting mechanism, is configured as a hinge mechanism having a flexible hinge, and performs a first portion 20 on which the telescopic element 1 is mounted and an operation of enlarging the displacement of the telescopic element 1. And a second part 30 to be used. The displacement of the telescopic element 1 is transmitted to the first part 20 and further transmitted to the second part 30 and expanded.

  The first portion 20 has a U-shaped fixing portion 21 having a cutout 23 into which the expansion and contraction element 1 is inserted, and a moving portion 22 that moves by expansion and contraction of the expansion and contraction element 1. One end of the telescopic element 1 is connected to the fixed part 21, and the other end of the telescopic element 1 is connected to the moving part 22. One end of the telescopic element 1 is fixed when the telescopic element 1 expands and contracts in the longitudinal direction. The moving part 22 moves with the movement of the other end. The moving part 22 is provided so as to enter the notch part 23. The fixing portion 21 has a plurality of mounting holes 24 penetrating in the thickness direction for mounting to the base material by bolts or the like.

  The second portion 30 has one end hingedly connected to the fixed portion 21 and the moving portion 22, and the other end has a pair of arms 31a and 31b for displacing the object to be displaced. That is, the base end of the arm 31a is connected to the hinge 32a extending from the upper end on one side of the fixed part 21 and the hinge 33a extending from the upper end of the moving part 22, and the base end of the arm 31b is connected to the fixed part 21. And a hinge 32b extending from the upper end of the moving section 22. The arms 31a and 31b are curved and extend along one side surface and the other side surface of the fixed portion 21, respectively. One ends of leaf springs 34a and 34b are respectively joined to the distal ends of the arms 31a and 31b, and the other ends of the leaf springs 34a and 34b are connected via a center piece 35 having a mounting hole 36 for mounting an object. Are linked. The object to be displaced is attached to the center piece 35.

  The hinges 32a, 32b, 33a, 33b are formed of a flexible material, the hinge 32a is provided integrally with the arm 31a and the fixed part 21, and the hinge 33a is provided integrally with the arm 31a and the moving part 22, 32b is provided integrally with the arm 31b and the fixed part 21, and the hinge 33b is provided integrally with the arm 31b and the moving part 22. Then, the hinges 32a, 32b, 33a, 33b are bent or deformed by the expansion and contraction of the expansion and contraction element 1, so that the movement of the moving part 22 and the rotation of the arms 31a, 31b are allowed.

  As a result, the arm 31a, 31b pivots via the hinges 32a, 32b, 33a, 33b due to the movement of the moving section 22 due to the expansion and contraction displacement of the expansion and contraction element 1, and the enlarged displacement is output from the centerpiece 35. It has become.

  In this way, the expansion / contraction displacement of the expansion / contraction element 1 is transmitted to the displacement enlarging mechanism 2 ', and can be transmitted to a movement target member (not shown) after being enlarged about 10 to 30 times.

  Specifically, the lower end of the elastic element 1 is attached to the fixed part 21, and the upper end of the elastic element 1 is attached to the moving part 22, and moves with the fixed part 21 in a state where no voltage is applied. The height positions of the upper ends of the portions 22 match, and when the telescopic element 1 is extended and displaced, the moving portion 22 rises with respect to the fixed portion 21, and the displacement causes the hinges 32 a, 32 b, 33 a, and 33 b to move. The arm 31a, 31b of the second portion 30 is transmitted through the arm 31a, 31b via the leaf springs 34a, 34b, and is attached to the center piece 35 and the center piece 35 via the leaf springs 34a, 34b. The moved member to be moved has an enlarged displacement that moves downward. Conversely, when the telescopic element 1 is contracted and displaced, the moving part 22 is lowered with respect to the fixed part 21 and the displacement is caused by the arms 31a and 31b of the second member 30 via the hinges 32a, 32b, 33a and 33b. , The arms 31a and 31b rotate so as to be separated from the fixed portion 21, and an enlarged displacement is generated in the center piece 35 via the leaf springs 34a and 34b.

  The leaf springs 34a and 34b each have a thin portion on one end side and the other end side, and have a thick portion thicker than the thin portion in an intermediate portion, and the leaf springs 34a and 34b are bent or deformed by the thick portion. Buckling at the time of occurrence is prevented.

  As in the first embodiment, the strain gauge 3 may be provided at a portion where distortion occurs due to expansion and contraction displacement of the expansion and contraction element 1, but is preferably provided at a portion where distortion is large, for example, at a portion corresponding to a hinge or in the vicinity thereof. Due to the large distortion, good sensitivity can be obtained. Although the example of FIG. 2 shows an example in which it is provided on a portion (front surface) corresponding to the hinge 32a, it may be a portion corresponding to the hinges 32b, 33a, 33b. A more suitable place for providing the strain gauge 3 is a leaf spring. FIG. 3 shows an example in which the strain gauge 3 is provided on a thin portion of the leaf spring 34b. The leaf springs 34a and 34b can obtain good sensitivity because the amount of distortion is increased. In addition, since the thin portion has a larger strain than the thick portion, more favorable sensitivity can be obtained by providing the strain gauge 3 in the thin portion of the leaf spring. Further, since the surface of the leaf springs 34a and 34b has a large area, the strain gauge 3 can be easily provided.

  In the actuator 101 configured as described above, as in the first embodiment, the driver 41 applies a predetermined voltage to the expandable element 1 based on a command from the control unit 42 of the drive unit 4, so that the expandable element 1 When the telescopic displacement occurs, the displacement is transmitted to the displacement enlarging mechanism 2 'which is a displacement transmitting mechanism. In the displacement magnifying mechanism 2 ′, the displacement of the expansion / contraction element 1 is converted into the rotational displacement of the arms 31 a, 31 b via the moving part 22 of the first member 20 and the hinges 32 a, 32 b, 33 a, 33 b of the second member 30. The rotational displacement causes the head piece 35 to be displaced in the longitudinal direction of the expansion / contraction element via the leaf springs 34a and 34b, and is output as a displacement magnified about 10 to 30 times. Then, the enlarged displacement is transmitted to a movement target member (not shown).

  When the movement target member is moved using the actuator 101 in this manner, the strain gauge 3 detects the strain of the displacement magnifying mechanism 2 ′ as the displacement transmission mechanism. At this time, the strain of the displacement magnifying mechanism 2 ′ itself is detected by the strain gauge 3, and this reflects the strain caused by the expansion and contraction of the expansion element 1. Therefore, when the displacement or the position of the elastic element 1 calculated from the detected value of the strain gauge 3 is deviated from the target, the target position sent to the control unit 42 based on the detection signal from the strain gauge 3 is determined. The corrected control signal is output to the driver 41 based on the correction, and the displacement of the telescopic element 1 can be corrected. Further, when there is an abnormality in the elastic element 1 such as when the elastic element 1 is excessively displaced or when the elastic element 1 does not expand or contract due to a short circuit or the like, a signal is sent to the alarm 43 to give an alarm (alarm). Or a measure such as outputting a stop signal to the driver 41 can be used to prevent the expansion element 1 from being destroyed.

  At this time, similarly to the first embodiment, there is no inconvenience such as when a strain gauge is attached to the expansion / contraction element, and an abnormality of the displacement magnifying mechanism 2 'can be reliably detected. To prevent the displacement magnifying mechanism 2 'from being destroyed, and to detect when the displacement magnifying mechanism 2', which is the displacement transmitting mechanism, is displaced by an external force and return the position of the displacement magnifying mechanism 2 '. Can be. Further, by providing the strain gauge 3 at or near the hinge portion of the displacement magnifying mechanism 2 ', a large displacement can be detected, and more accurate strain detection can be performed.

<Third embodiment>
FIG. 4 is a front view showing an actuator according to a third embodiment of the present invention.
In the present embodiment, an example in which a pressurizing mechanism 5 is provided as a displacement transmission mechanism will be described.

  As shown in FIG. 4, the actuator 102 includes a telescopic element, a pressurizing mechanism 5 as a displacement transmission mechanism, a strain gauge 3 mounted on the pressurizing mechanism, and a driving unit 4 that drives the telescopic element 1. . The configurations of the expansion element 1, the strain gauge 3, and the driving unit 4 are the same as those of the first embodiment, and thus the description is omitted.

  When the extensible element 1 is made of a ceramic material that is weak against tensile force, such as a piezoelectric element, the pressurizing mechanism 5 that is a displacement transmission mechanism is about １ ／ to に 対 し て of the force generated by the extensible element 1. Is applied in the expansion and contraction direction of the expansion and contraction element 1 and a pair of head pieces 51 and 52 fixed to one end and the other end of the expansion and contraction element 1 in the expansion and contraction direction (length direction) by bonding. And two linearly-applied compressive force applying portions 53 provided so as to be bridged between the pair of head pieces 51 and 52. The head pieces 51 and 52 and the compressive force applying section 53 are integrated. A moving target member (not shown) is mounted on the headpiece 51, and the headpiece 52 is fixed by a fixing jig 54. Although the shape of the head pieces 51 and 52 is a rectangular parallelepiped, the shape is not particularly limited, and can be appropriately set according to, for example, the shape of the expansion element 1. Further, the number of the compressive force applying portions 53 is not limited to two, and may be three or four. Further, for example, when the elastic element 1 has a space in the center of a donut shape or the like, the compressive force applying portion 53 penetrates through the space. May be one.

  When the expansion element 1 is mounted on the pressurizing mechanism 5, the compression element 53 is stretched by applying a tensile force to the compression mechanism 5 in the expansion and contraction direction of the expansion element 1. Is mounted between the pair of head pieces 51 and 52, and then the tensile force is released. As a result, a state where a compressive force corresponding to the tensile force is applied to the elastic element 1 is provided.

  Then, the pressurizing mechanism 5 is transmitted with the telescopic displacement along the longitudinal direction of the telescopic element 1, and the displacement is output from the head pieces 51 and 52. At this time, since the head piece 52 is fixed by the fixing jig 54, the head piece 52 is an immovable part. Therefore, when the extendable element 1 expands and contracts, only the head piece 51 is displaced in the same direction as the extensible element 1 as indicated by the arrow in FIG. Then, the displacement can be transmitted to a movement target member (not shown).

  Instead of attaching the moving target member to the headpiece 51 and fixing the headpiece 52, the moving target member may be mounted on the headpiece 52 and fixing the headpiece, or both the headpieces 51 and 52 may be fixed. The movement target member may be mounted on both of them, and both may be operated.

  In the pressurizing mechanism 5, the strain caused by the expansion and contraction of the expandable element 1 is generated in the compressive force applying section 53. Since the compressive force imparting section 53 is substantially uniformly distorted, almost the same amount of strain can be obtained regardless of the position where the strain gauge 3 is provided.

  In the actuator 102 configured as described above, the driver 41 applies a predetermined voltage to the expandable element 1 based on a command from the control unit 42 of the drive unit 4 as in the first embodiment, so that the expandable element 1 When the telescopic displacement occurs, the displacement is transmitted to the pressurizing mechanism 5, which is a displacement transmitting mechanism. In the pressurizing mechanism 5, the displacement of the telescopic element 1 is transmitted, and the displacement is output from the head pieces 51 and 52. Then, the displacement is transmitted to a movement target member (not shown).

  When the movement target member is moved using the actuator 102 in this manner, the strain gauge 3 detects the strain of the pressurizing mechanism 5 as the displacement transmission mechanism. At this time, the strain of the pressurizing mechanism 5 itself is detected by the strain gauge 3, which reflects the strain due to the expansion and contraction of the expansion and contraction element 1. Therefore, when the displacement or the position of the elastic element 1 calculated from the detected value of the strain gauge 3 is deviated from the target, the target position sent to the control unit 42 based on the detection signal from the strain gauge 3 is determined. The corrected control signal is output to the driver 41 based on the correction, and the displacement of the telescopic element 1 can be corrected. Further, when there is an abnormality in the elastic element 1 such as when the elastic element 1 is excessively displaced or when the elastic element 1 does not expand or contract due to a short circuit or the like, a signal is sent to the alarm 43 to give an alarm (alarm). Or a measure such as outputting a stop signal to the driver 41 can be used to prevent the expansion element 1 from being destroyed.

  At this time, similarly to the first embodiment, the inconvenience of attaching a strain gauge to the expansion element does not occur, and the abnormality of the pressurizing mechanism 5 can be reliably detected. The destruction of the pressure mechanism 5 can be prevented beforehand, and when the position of the pressurization mechanism 5 which is the displacement transmission mechanism shifts due to an external force, it can be detected and the position of the pressurization mechanism 5 can be returned.

<Other applications>
As described above, some embodiments of the present invention have been described, but the present invention is not limited to the above embodiments, and can be variously modified. For example, the displacement transmission mechanism is not limited to the above embodiment. Specifically, in the first embodiment and the second embodiment, examples in which different types of displacement magnifying mechanisms are used as hinge mechanisms having hinges as displacement transmission mechanisms have been described, but hinges having hinges have been described. As long as the mechanism is not limited to the two displacement magnifying mechanisms, any type of displacement magnifying mechanism can be used, and not limited to the displacement magnifying mechanism, any type of displacement reducing mechanism can be used. Further, the pressurizing mechanism used as the displacement transmitting mechanism is not limited to the above configuration as long as it has a function of transmitting the displacement.

  Further, in the above-described embodiment, an example is described in which a single displacement transmission mechanism is used, but a plurality of displacement transmission mechanisms may be used. For example, as in the third embodiment, the telescopic element is mounted on the pressurizing mechanism, and the pressurizing mechanism with the telescopic element mounted is connected to the hinge mechanism, for example, the displacement as in the first and second embodiments. It may be configured to be attached to the enlargement mechanism. In this case, both the pressurizing mechanism and the hinge mechanism are used as the displacement transmitting mechanism, and the strain gauge can be used for either or both of them.

1; telescopic element 2, 2 '; displacement enlargement mechanism (displacement transmission mechanism)
3; strain gauge 4; drive unit 5; pressurizing mechanism (displacement transmitting mechanism)
11, 12; head pieces 13a, 13b, 15a, 15b, 17a, 17b, 19a, 19b, 31a, 32b, 33a, 33b; hinges 16a, 16b; output member 20, first part 30, second part 21; Unit 22; moving units 31a, 31b; arms 34a, 34b; leaf spring 35; headpiece 41; driver 42; control unit 43; alarms 51, 52; headpiece 53; compression force applying units 100, 101, 102;

Claims (3)

A telescopic element that expands and contracts in a predetermined direction;
A displacement transmission mechanism to which the telescopic element is mounted and transmits the telescopic displacement of the telescopic element to a moving object,
In the displacement transmission mechanism, a strain gauge provided at a position where a strain due to the displacement of the expansion element is generated,
A drive unit that expands and contracts the expandable element,
While correcting the expansion and contraction of the telescopic element based on the detected value of the strain gauge, grasping the abnormality of the telescopic element or the displacement transmission mechanism based on the detected value of the strain gauge,
The displacement transmission mechanism,
A pair of head pieces fixed to one end face and the other end face of the expansion element in the direction of expansion and contraction, and a linear compression force applied integrally with the head piece and provided so as to be bridged between the head pieces; Having a pressurizing mechanism for applying a compressive force in the direction of expansion and contraction of the expansion and contraction element,
A portion between the pair of head pieces of the compressive force applying portion forms one straight line, and the portion forming the one straight line is distorted in the direction of the one straight line corresponding to the direction of expansion and contraction of the expansion and contraction element,
The actuator according to claim 1, wherein the strain gauge is provided at a portion of the compression force applying unit that forms the one straight line . The drive unit has a driver that provides a drive signal to the telescopic element, and a control unit that controls the driver.
The control unit, based on the detected value of the strain gauge, and corrects the input target position, when the detected value of the strain gauge indicates an abnormality of the telescopic element or the displacement transmission mechanism, The actuator according to claim 1, wherein the driver is stopped or an alarm is generated.   3. The actuator according to claim 1, wherein the expansion element is one of a piezoelectric element, a magnetostrictive element, and a shape memory alloy element.

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