JP2008099399A - Piezoelectric actuator and pressurizing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric actuator which can impart an appropriate compressive force to a piezoelectric element, irrespective of the dimensions of the piezoelectric element. <P>SOLUTION: The piezoelectric actuator 100 is provided with the piezoelectric element 1 which elongates and contracts according to an applied voltage, and a displacement amplifying mechanism 7 which amplifies the elongation/contraction displacement of the piezoelectric element 1, and makes the amplified displacement act on an object. The displacement amplifying mechanism 7 comprises a displacement amplifying operation part 20, which performs a displacement amplifying operation for amplifying the elongation/contraction displacement of the piezoelectric element 1, and a compression coil spring 17, which is arranged at a part where there occurs displacement larger than the elongation/contraction displacement of the piezoelectric element of the displacement amplifying operation part 20, and imparts the compressive force with respect to the piezoelectric element 1, accompanied by the displacement amplifying operation of the displacement amplifying operation part 20, when the piezoelectric element 1 is elongated and contracted. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a piezoelectric actuator that applies a displacement to an object using the expansion and contraction displacement of a piezoelectric element, and a pressurizing method for applying a compressive force to the piezoelectric element in such a piezoelectric actuator.

  Actuators, which are mechanisms for "moving" something, are used in everything from various industrial machines, automobiles, aircraft, medical-related equipment to personal electrical products. Actuators include, for example, solenoids and air valves in industrial mechanisms, moving mechanisms that move magnetic chips for reading and writing to hard disk drives in personal computers, and vibration motors that generate vibrations in mobile phones. Etc. are used. At present, actuators that use an "electromagnetic force" that is an attractive force or a repulsive force generated between a magnetic field generated by a current flowing in a coil and a permanent magnet are most frequently used. However, although electromagnetic force has an advantage that force can be generated even between spatially separated objects, (1) mechanical energy generated with respect to input electric energy is small. Less, energy efficiency is significantly lower, for example, less than a few percent, (2) not suitable for fast response, for example less than a millisecond, (3) when holding an object in a certain position, the current must continue to flow; As a result, the electric energy consumption is further increased.

  An actuator using a piezoelectric element is known as an actuator that can eliminate such a drawback. Piezoelectric elements are constructed so that a phenomenon called the “piezoelectric effect” in which the entire piezoelectric material expands or contracts by forming an electric field in the piezoelectric material can be realized at a relatively low voltage level of about 100V. Yes, (1) More than 60% of the input electric energy is converted into mechanical energy, for example, the force generated by a 10 mm × 10 mm element reaches 300 kgf, and the energy efficiency is extremely high. (2) Several kHz (3) When an object is held at a certain position, it is necessary to apply a voltage, but current does not flow, so that electric energy consumption can be suppressed. 4) It has excellent points such as being suitable for downsizing and thinning. On the other hand, since the generated displacement of the piezoelectric element is usually several μm to several tens of μm, which is less than the diameter of a single hair, its application is extremely limited. In order to compensate for this drawback, an actuator of a type that expands the generated displacement of a piezoelectric element several times to several tens of times in combination with a displacement expansion mechanism (hereinafter referred to as a piezoelectric element displacement expansion mechanism type actuator) has been developed. In such a piezoelectric element displacement magnifying mechanism type actuator, the displacement generated by the piezoelectric element is increased from several times to several tens of times. As a result, the generated displacement becomes 100 μm to 1 mm or more. Become.

  By the way, since a piezoelectric element is generally made of a ceramic material, it has brittleness like pottery and is strong against compression but weak against tension. For this reason, when using a piezoelectric element as an actuator, it is required to give a compressive force of about 1/5 to 1/2 with respect to the force generated from the piezoelectric element. As a pressurizing structure for applying a compressive force to the piezoelectric element, as shown in FIG. 5, between the head pieces B and C provided in contact with one end and the other end of the piezoelectric element A in advance, respectively, A structure in which a bellows member D in a state of being stretched by applying a tensile force is installed and a contraction force that tries to return to the bellows member D is used is known (for example, see Non-Patent Document 1).

  In such a structure, in the case of a piezoelectric element having a small cross-sectional area of about 2 mm × 3 mm, for example, the generated force of the piezoelectric element is as small as about 200 N (about 20 kgf), and the pressure applied to the piezoelectric element is 1 / of that Since it can be as small as 2 to 1/5, which is about 4 to 10 kgf, it is easy to apply. However, when the cross-sectional area of the piezoelectric element is increased to, for example, about 10 mm × 10 mm, the generated force of the piezoelectric element also becomes 300 kgf, so that the required pressure reaches 60 to 150 kgf, and within the limit stress of the constituent material of the bellows member The bellows member must be large or thick so that this force can be exerted, which is difficult to apply in practice.

In addition, such a structure requires a relatively complicated shape of the bellows member to be processed with high accuracy, and thus increases the cost.
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  The present invention has been made in view of such circumstances, and provides a piezoelectric actuator and a pressurizing method capable of easily applying an appropriate compressive force to the piezoelectric element regardless of the size of the piezoelectric element. The purpose is to do.

  It is another object of the present invention to provide a piezoelectric actuator and a pressurizing method capable of applying an appropriate compressive force to a piezoelectric element without increasing the cost.

In order to solve the above problems, in the first aspect of the present invention, a piezoelectric element that expands and contracts in response to an applied voltage, and a displacement that expands the expansion and contraction displacement of the piezoelectric element and causes the expanded displacement to act on an object. A piezoelectric actuator comprising an enlargement mechanism, wherein the displacement enlargement mechanism includes a displacement enlargement operation unit that performs a displacement enlargement operation for enlarging an expansion / contraction displacement of the piezoelectric element, and an expansion / contraction displacement of the piezoelectric element of the displacement enlargement operation unit. A compression force applying means that is provided in a portion where a larger displacement is generated and applies a compressive force to the piezoelectric element in accordance with a displacement expansion operation of the displacement expansion operation unit when the piezoelectric element expands and contracts; A piezoelectric actuator is provided.

  In the first aspect, the displacement magnifying mechanism may further include a displacement transmission unit that contacts the piezoelectric element and transmits an expansion / contraction displacement of the piezoelectric element to the displacement magnifying operation unit. The displacement transmission unit includes a first contact member having one of the contact portions of the piezoelectric element, and a second contact member having the other of the contact portions of the piezoelectric element. As the piezoelectric element expands and contracts, a relative displacement corresponding to the expansion / contraction displacement of the piezoelectric element is generated between the first contact member and the second contact member, and the displacement enlarging operation unit is The relative displacement between the first contact member and the second contact member is transmitted to expand the displacement, and the expanded displacement acts on the object. Can do. Further, the displacement enlarging operation portion is hinged to the first and second contact members, respectively, so that relative displacement between the first contact member and the second contact member is achieved. It has an arm that rotates or swings along with it, and an enlarged displacement is applied to the object by the rotation or swinging of the arm. Furthermore, as the compressive force applying means, a spring member having one end attached to the arm and the other end attached to the displacement transmitting portion can be used.

  According to a second aspect of the present invention, there is provided a piezoelectric element that expands and contracts in response to an applied voltage, and a displacement enlarging mechanism that expands the expansion and contraction displacement of the piezoelectric element and causes the expanded displacement to act on the object. In the piezoelectric actuator, the displacement enlarging mechanism has two abutting portions that abut on one end and the other end in the expansion / contraction direction of the piezoelectric element, and in the state where the piezoelectric element is not attached, The length between the two contact portions is configured to be shorter than the length of the piezoelectric element in the expansion / contraction direction, and when the piezoelectric element and the displacement magnifying mechanism are assembled, the piezoelectric element becomes the two contact portions. There is provided a piezoelectric actuator characterized in that a compression force is exerted between the piezoelectric elements.

  In the second aspect, the displacement enlarging mechanism includes a displacement enlarging operation unit that performs an enlarging operation of the expansion / contraction displacement of the piezoelectric element and the two contact portions, and the expansion / contraction displacement of the piezoelectric element is increased by the displacement expansion. It can have a displacement transmission part transmitted to an operation part. The displacement transmission unit includes a first contact member having one of the contact portions of the piezoelectric element, and a second contact member having the other of the contact portions of the piezoelectric element. As the piezoelectric element expands and contracts, a relative displacement corresponding to the expansion / contraction displacement of the piezoelectric element is generated between the first contact member and the second contact member, and the displacement enlarging operation unit is The relative displacement between the first abutting member and the second abutting member is transmitted to enlarge the displacement, and the enlarged displacement acts on the object. Can do. Further, the displacement enlarging operation portion is hinged to the first and second contact members, respectively, so that relative displacement between the first contact member and the second contact member is achieved. It has an arm that rotates or swings along with it, and an enlarged displacement is applied to the object by the rotation or swinging of the arm.

  According to a third aspect of the present invention, there is provided a piezoelectric element that expands and contracts according to an applied voltage, and a displacement expansion mechanism that expands and contracts the expansion and contraction of the piezoelectric element and causes the expanded displacement to act on an object. The displacement enlarging mechanism is a preloading method in a piezoelectric actuator for applying a compressive force to the piezoelectric element in a piezoelectric actuator having a displacement enlarging operation unit that performs a displacement enlarging operation for enlarging the expansion and contraction displacement of the piezoelectric element, Applying compressive force to the piezoelectric element in accordance with the displacement enlarging operation of the displacement enlarging operation unit when the piezoelectric element expands or contracts in a portion where the displacement of the operating unit is larger than the expansion and contraction displacement of the piezoelectric element. A preload method is provided.

  According to a fourth aspect of the present invention, there is provided a piezoelectric element that expands and contracts according to an applied voltage, and a displacement expansion mechanism that expands and contracts the expansion and contraction of the piezoelectric element and causes the expanded displacement to act on an object. The displacement enlarging mechanism is a preload method in a piezoelectric actuator for applying a compressive force to the piezoelectric element in a piezoelectric actuator having two abutting portions that abut one end and the other end in the expansion / contraction direction of the piezoelectric element, When the piezoelectric element is not attached, the length between the two contact portions is made shorter than the length of the piezoelectric element in the expansion / contraction direction, and when assembling the piezoelectric element and the displacement enlarging mechanism, A preloading method is provided, wherein the piezoelectric element is inserted between the two contact portions so as to exert a compressive force on the piezoelectric element.

  According to the first and third aspects of the present invention, the displacement enlarging operation section for performing the displacement enlarging operation for enlarging the expansion / contraction displacement of the piezoelectric element is formed in a portion where displacement larger than the expansion / contraction displacement of the piezoelectric element of the displacement enlarging operation section occurs When the piezoelectric element expands and contracts, a compressive force is applied to the piezoelectric element in accordance with the displacement expanding operation of the displacement expanding operation unit. Therefore, the piezoelectric element is suitable for the piezoelectric element regardless of the size of the piezoelectric element. It becomes possible to easily apply a compressive force. That is, when a force corresponding to the displacement expanded by the displacement expansion operation unit is applied to the piezoelectric element, the force is also expanded with the displacement expansion, and a large compressive force according to the size of the piezoelectric element can be applied. Further, since the force for urging the displacement enlarging operation portion can be set small, the urging means can be configured with an inexpensive one, and the cost can be kept low.

  According to the second and fourth aspects of the present invention, the piezoelectric element is attached to the length between the two abutting parts that abut on one end and the other end in the expansion / contraction direction of the piezoelectric element of the displacement enlarging mechanism. When not assembled, the length of the piezoelectric element is shorter than the length of the expansion / contraction direction, and when assembling the piezoelectric element and the displacement enlarging mechanism, the piezoelectric element is inserted into the mounting portion so as to exert a compressive force on the piezoelectric element. Therefore, it is not necessary to provide a special mechanism for applying a compressive force to the piezoelectric element such as a conventionally used bellows member. For this reason, it becomes possible to give an appropriate compressive force to the piezoelectric element without increasing the cost.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic front view of a piezoelectric actuator as an embodiment according to the present invention.

  The piezoelectric actuator 100 includes a piezoelectric element 1 that expands and contracts according to an applied voltage, and a displacement enlarging mechanism 7 that expands the expansion and contraction displacement of the piezoelectric element 1 and applies the expanded displacement to an object. .

  The piezoelectric element 1 is configured in a columnar or rectangular parallelepiped shape having a cross-sectional area of 10 mm × 10 mm and a length of 40 mm, for example, by laminating a plurality of plate-shaped piezoelectric bodies. The piezoelectric element 1 includes electrical terminals 2 and 3 for applying a voltage to the side surface, and is configured to expand and contract in the length direction when a voltage is applied between the electrical terminals 2 and 3. .

  The displacement enlarging mechanism 7 includes a displacement enlarging operation unit 20 that performs an enlarging operation of the expansion / contraction displacement of the piezoelectric element 1 and a displacement transmitting unit 30 that transmits the expansion / contraction displacement of the piezoelectric element 1 to the displacement enlarging operation unit 20. The displacement transmission unit 30 includes a first contact member 4 that contacts one end in the length direction of the piezoelectric element 1 and a second contact member 6 that contacts the other end in the length direction of the piezoelectric element. ing. The first abutting member 4 is formed in a U shape having a notch 5 into which the piezoelectric element 1 is inserted along the length direction, and the end surface of the notch 5 is one end in the length direction of the piezoelectric element 1 ( It is comprised so that it may contact | abut to a lower end part. The first contact member 4 has a plurality of attachment holes 9 penetrating in the thickness direction for attachment to the base material by bolts or the like. The second contact member 6 is provided so as to enter the notch 5. The first contact member 4 and the second contact member 6 are configured to sandwich the piezoelectric element 1.

  One end of the displacement enlarging operation unit 20 is hinged to the first contact member 4 and the second contact member 6, and a displacement object is attached to the other end. The second contact member 6 is provided with a pair of arms 12 that act on the object to be enlarged by swinging or rotating with the movement of 6.

  The base end portion of each arm 12 includes a hinge 10 extending from the upper end on one side of the U-shaped first contact member 4 and a hinge 11 extending from the upper end of the second contact member 6. The second contact members 4 and 6 are coupled to each other. These arms 12 are curved and extend along the periphery of the first contact member 4.

  The height positions of the upper ends of the first abutting member 4 and the second abutting member 6 of the displacement transmitting portion 30 are the same, and the lower end portion of the piezoelectric element 1 is fixed to the first abutting member 4. Therefore, when a displacement occurs in the direction in which the voltage is applied to the piezoelectric element 1, a displacement corresponding to the displacement is generated between the first contact member 4 and the second contact member 6. This displacement is transmitted to the arm 12 of the displacement enlarging operation unit 20 via the hinges 10 and 11, and the arm 12 rotates so as to be close to the peripheral edge of the first contact member 4. Conversely, when a displacement occurs in the direction in which the piezoelectric element 1 contracts, a displacement corresponding to the displacement is generated between the first contact member 4 and the second contact member 6, and the hinges 10 and 11 are moved. And is transmitted to the arm 12 of the displacement enlarging operation unit 20 via the first contact member 4 so as to be separated from the peripheral edge of the first contact member 4. One end of a leaf spring 14 is joined to the distal end of the arm 12, and the other end of each leaf spring 14 is connected via a center piece 15 having an attachment hole 16 for attaching an object. . Each leaf spring 14 has thin portions 14a and 14c at one end side and the other end side, respectively, and has a thick portion 14b thicker than the thin portions 14a and 14c at an intermediate portion. Occurrence of buckling at the time of bending or bending deformation is prevented.

  The hinge portions 10 and 11 that hinge-couple the arm 12 to the first contact member 4 and the second contact member 6 are formed of a flexible material, and the arm 12 and the first contact member 4, respectively, It is provided integrally with the arm 12 and the second contact member 6, and allows the movement of the second contact member 6 and the rotation or swinging of the arm 12 by bending or bending deformation. It is configured.

  The arm 12 is urged in a direction away from the peripheral edge of the first contact member 4 by a compression coil spring 17 as a compression force application unit that applies a compression force to the piezoelectric element 1. Thereby, the urging force of the compression coil spring 17 is transmitted to the first contact member 4 and / or the second contact member 6, and the first contact member 4 and / or the second contact member with respect to the piezoelectric element 1. The compressive force is applied to the piezoelectric element 1 through the contact member 6. Each compression coil spring 17 is attached at one end to a portion where a displacement larger than the expansion / contraction displacement of the piezoelectric element of the arm 12, for example, the tip, and the other end is attached to the peripheral portion of the first contact member 4. ing.

  In the piezoelectric actuator 100 configured as described above, when a DC voltage of, for example, 100 V is applied between the electrical terminals 2 and 3, the piezoelectric element 1 expands by, for example, 28 μm, and accordingly, the second contact member 6 is expanded. Is displaced along the length direction of the piezoelectric element 1. Since the hinge part 11 is also displaced with respect to the hinge part 10 by the displacement of the second contact member 6, the pair of arms 12 coupled to the hinge parts 10, 11 rotate so as to approach each other by the lever principle, The tip 13 of each arm 12 is displaced, for example, by 290 μm (total of 580 μm by the two arms 12). Following this, the leaf springs 14 are also bent or bent so as to be close to each other, and the displacement object attached to the head piece 15 and the head piece 15 is, for example, 806 μm along the length direction of the piezoelectric element 1, that is, The displacement of the piezoelectric element 1 is about 29 times the amount of expansion.

  On the other hand, an appropriate compression force (pressure) is applied to the piezoelectric element 1 via the first contact member 4 and / or the second contact member 6 by the compression coil spring 17 that biases the arm 12. Therefore, damage to the piezoelectric element 1 can be reliably prevented.

Here, the reason why an appropriate compressive force can be applied to the piezoelectric element 1 by the compression coil spring 17 will be described in detail. FIG. 2 is a conceptual diagram for explaining the relationship between the force and displacement generated in the piezoelectric element 1 and the force and displacement generated in the displacement magnifying mechanism 7 in the piezoelectric actuator.
When the displacement amount ξ _S of the output section (or displacement expansion operation section) of the displacement enlarging mechanism 7 when the piezoelectric element 1 is expanded and contracted is n times the displacement amount ξ _O of the piezoelectric element 1 (ξ _S = n × ξ _O ) If the energy loss generated in the displacement magnifying mechanism 7 is not considered, if the force F _S is applied to the output part of the displacement magnifying mechanism 7, the force F _O acting on the piezoelectric element is the force F Compared with the case where the force F _O is directly applied to the piezoelectric element 1, it is only necessary to apply n / 1 force compared to the case where _S is n times (F _O = n × F _S ). That is, the displacement magnifying mechanism 7 is a mechanism for magnifying the force from the viewpoint of the displacement object side to the piezoelectric element 1 side. Therefore, if the displacement of the piezoelectric element 1 is increased 10 times at the output portion of the displacement magnifying mechanism 7, a compression force applying means such as a spring is provided at the output portion to apply a compressive force to the piezoelectric element 1, thereby Compared with the case where the compressive force is directly applied to the element 1, a force of 1/10 is sufficient.

  Utilizing such a property, as shown in FIG. 1, the arm 12 is moved so that a compressive force acts on the piezoelectric element 1 via the first contact member 4 and / or the second contact member 6. When energized, even if the piezoelectric element 1 has a large cross-sectional area of, for example, 10 mm × 10 mm, a large compressive force corresponding to the cross-sectional area of the piezoelectric element 1 can be applied with a small force. Therefore, a general coil spring may be used as the compression coil spring 17 used as the compression force application means, and the conventionally used bellows member is no longer necessary, and thus it can be manufactured at low cost. By providing the compression coil spring 17 so as to urge the other end side or the tip side of the arm 12 as much as possible, an appropriate compression force can be applied to the piezoelectric element 1 with a smaller urging force.

  When the piezoelectric element 1 is extended by, for example, 28 μm and the head piece 15 is displaced by, for example, 806 μm, the joint point 18 between the compression coil spring 17 and the arm 12 and the joint point 19 between the compression coil spring 17 and the first contact member 4. Is 230 μm, that is, when the displacement is about 8.2 times the expansion amount of the piezoelectric element 1, for example, if the compression coil spring 17 is configured by winding a steel wire having a wire diameter of 1.2 mm around an outer spring diameter of 10 mm. The force applied to the arm 12 by the compression coil spring 17 is 4 kgf, and the applied pressure to the piezoelectric element 1 is 65.6 kgf, which is an appropriate applied pressure.

  When the application of the DC voltage between the electrical terminals 2 and 3 is stopped, the extending piezoelectric element 1 contracts, and the force to return the hinge parts 10 and 11 and the leaf spring 14 that have been bent or bent to the original state. In addition, the two arms 12 are turned away from each other by the urging force of the compression coil spring 17, and accordingly, the second contact member 6 moves following the piezoelectric element 1.

Next, another embodiment of the piezoelectric actuator according to the present invention will be described.
FIG. 3 is a schematic front view of a piezoelectric actuator as another embodiment according to the present invention, and FIG. 4 is a diagram showing a state in which the piezoelectric element and the displacement enlarging mechanism are separated in this piezoelectric actuator.

This piezoelectric actuator 100 ′ is obtained by changing the structure of the displacement enlarging mechanism 7 of the piezoelectric actuator 100. The same parts as those of the piezoelectric actuator 100 are denoted by the same reference numerals and description thereof is omitted. The displacement enlarging mechanism 7 ′ of the piezoelectric actuator 100 ′ does not have the compression coil spring 17, but has a second contact member 6 ′ instead of the second contact member 6. The second contact member 6 ′ has substantially the same shape as the second contact member 6, but extends slightly to one side in the length direction of the piezoelectric element 1 from the second contact member 6. Yes. For this reason, as shown in FIG. 4, when the piezoelectric element 1 is not disposed between the first contact member 4 and the second contact member 6, the contact surface of the first contact member 4. distance L _m of (abutting) the contact surface of the second contact member 6 'and the (contact end) is smaller than the length L _p of the piezoelectric element 1. As a result, as shown in FIG. 3, when the piezoelectric element 1 is disposed between the first contact member 4 and the second contact member 6 ′ so as to be inserted, for example, the first relative to the piezoelectric element 1 is obtained. The pressing force of the first contact member 4 and / or the second contact member ′, that is, the compressive force to the piezoelectric element 1 acts.

In the piezoelectric actuator 100 ′, the hinge portions 10 and 11 are formed integrally with the first contact member 4 and the second contact member 6 ′ and the arm 12, and the first contact member 4 and the second contact member 4 are formed. When the force is transmitted between the contact member 6 ′ and the arm 12, the hinge portions 10 and 11 are bent or bent, and therefore there is a rigidity value suitable for generating the bending or bending deformation. Therefore, the length L _p of the piezoelectric element 1 is different from the distance L _m between the contact surface (contact end) of the first contact member 4 and the contact surface (contact end) of the second contact member 6. δ can be calculated by the following equation (1), where k _{m is} the rigidity value of the second abutting member and F is a required pressure applied to the piezoelectric element 1.
_{δ = F / k m ··· (} 1)
As a specific example, the piezoelectric element 1 is a cross-sectional area 10 mm × 10 mm, when the length of 40mm, the rigidity value _{k m} is ^7.4E +6 N / m, given the pressure F is set to 600N, the difference from (1) δ is calculated to be 81 μm. That is, in this case, the distance L _m between the contact surface (contact end) of the first contact member 4 and the contact surface (contact end) of the second contact member 6 ′ is defined as the piezoelectric element 1. If the length L _p is made 81 μm smaller than the length L _p , an appropriate pressure 600 N can be applied to the piezoelectric element 1.

  In the present embodiment, the conventionally used bellows member is no longer necessary, and the compression coil spring used in the previous embodiment is not necessary, so that it can be manufactured at a lower cost.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment, and various modifications can be made. In the above-described embodiment, the arm is disposed so as to extend along the peripheral edge of the first contact member. However, the arm may be disposed so as to be separated from the first contact member. Moreover, in the said embodiment, the compression coil spring which urges | biases an arm was attached to the 1st contact member on account of having formed the 1st contact member larger than the 2nd contact member. Depending on the shape and the like of the second contact member, the second contact member may be attached. Furthermore, in the above embodiment, the compression coil spring is used as the biasing means for biasing the arm. However, the present invention is not limited to this, and other springs such as a tension coil spring may be used, and an elastic body such as rubber may be used. May be.

It is a schematic front view of the piezoelectric actuator as one embodiment concerning the present invention. It is a conceptual diagram for demonstrating the relationship between the force and displacement which generate | occur | produce in a piezoelectric element in a piezoelectric actuator, and the force and displacement which generate | occur | produce in a displacement expansion mechanism. It is a schematic front view of the piezoelectric actuator as other embodiment which concerns on this invention. It is a figure of the state which isolate | separated the piezoelectric element and the displacement expansion mechanism in a piezoelectric actuator. It is a figure for demonstrating the pressurization aspect to the piezoelectric element in the conventional piezoelectric actuator.

Explanation of symbols

1: Piezoelectric element 4: 1st contact member 6, 6 ': 2nd contact member 7, 7': Displacement expansion mechanism 12: Arm 10, 11: Hinge part 17: Compression coil spring (biasing means, Spring member)
20: Displacement expansion operation unit 30: Displacement transmission unit 100, 100 ': Piezoelectric actuator

Claims (11)

A piezoelectric element that expands and contracts in response to an applied voltage;
A displacement enlarging mechanism for enlarging the expansion / contraction displacement of the piezoelectric element and causing the enlarged displacement to act on the object;
A piezoelectric actuator comprising:
The displacement enlarging mechanism is
A displacement enlarging operation unit for performing a displacement enlarging operation for enlarging the expansion and contraction displacement of the piezoelectric element;
The displacement enlarging operation part is provided in a portion where a displacement larger than the expansion / contraction displacement of the piezoelectric element occurs, and the piezoelectric element is compressed with the displacement enlarging operation of the displacement enlarging operation part when the piezoelectric element expands / contracts. A piezoelectric actuator comprising compressive force applying means for applying force.   2. The piezoelectric actuator according to claim 1, wherein the displacement enlarging mechanism further includes a displacement transmission unit that contacts the piezoelectric element and transmits an expansion / contraction displacement of the piezoelectric element to the displacement enlarging operation unit. The displacement transmitting portion includes a first contact member having one of the contact portions of the piezoelectric element, and a second contact member having the other of the contact portions of the piezoelectric element, Along with the expansion and contraction of the piezoelectric element, a relative displacement corresponding to the expansion and contraction displacement of the piezoelectric element occurs between the first contact member and the second contact member.
The displacement enlarging operation unit is configured to transmit the relative displacement between the first contact member and the second contact member to expand the displacement, and use the expanded displacement as a target. The piezoelectric actuator according to claim 2, wherein the piezoelectric actuator is operated.   The displacement enlarging operation portion is hinged to the first and second contact members, respectively, and is associated with relative displacement between the first contact member and the second contact member. 4. The piezoelectric actuator according to claim 3, further comprising an arm that pivots or swings, and an enlarged displacement is applied to the object by the pivoting or swinging of the arm.   5. The piezoelectric actuator according to claim 4, wherein the compression force applying means is a spring member having one end attached to the arm and the other end attached to the displacement transmission unit. A piezoelectric element that expands and contracts in response to an applied voltage;
A piezoelectric actuator comprising a displacement enlarging mechanism for enlarging the expansion / contraction displacement of the piezoelectric element and causing the enlarged displacement to act on an object,
The displacement enlarging mechanism has two abutting portions that abut on one end and the other end in the expansion / contraction direction of the piezoelectric element,
In a state where the piezoelectric element is not attached, the length between the two contact portions is configured to be shorter than the length in the expansion / contraction direction of the piezoelectric element,
When the piezoelectric element and the displacement enlarging mechanism are assembled, the piezoelectric element is inserted between the two contact portions, and a compressive force is exerted on the piezoelectric element. Piezoelectric actuator. The displacement enlarging mechanism is
A displacement enlarging operation unit for enlarging the expansion and contraction displacement of the piezoelectric element;
The piezoelectric actuator according to claim 6, further comprising: a displacement transmitting portion that includes the two contact portions and transmits expansion / contraction displacement of the piezoelectric element to the displacement enlarging operation portion. The displacement transmitting portion includes a first contact member having one of the contact portions of the piezoelectric element, and a second contact member having the other of the contact portions of the piezoelectric element, Along with the expansion and contraction of the piezoelectric element, a relative displacement corresponding to the expansion and contraction displacement of the piezoelectric element occurs between the first contact member and the second contact member.
The displacement enlarging operation unit is configured to transmit the relative displacement between the first contact member and the second contact member to expand the displacement, and use the expanded displacement as a target. The piezoelectric actuator according to claim 7, wherein the piezoelectric actuator is operated.   The displacement enlarging operation portion is hinged to the first and second contact members, respectively, and is associated with relative displacement between the first contact member and the second contact member. 9. The piezoelectric actuator according to claim 8, further comprising an arm that rotates or swings, and an enlarged displacement is applied to the object by the rotation or swing of the arm. A piezoelectric element that expands and contracts in response to an applied voltage;
A displacement enlarging mechanism that enlarges the expansion / contraction displacement of the piezoelectric element and causes the enlarged displacement to act on an object, and the displacement enlarging mechanism performs a displacement enlarging operation for enlarging the expansion / contraction displacement of the piezoelectric element. A piezoelectric actuator preload method for applying a compressive force to the piezoelectric element in a piezoelectric actuator having an expanding operation part,
When the piezoelectric element expands or contracts in a portion where displacement greater than the expansion / contraction displacement of the piezoelectric element of the displacement expansion operation unit occurs, a compressive force is applied to the piezoelectric element along with the displacement expansion operation of the displacement expansion operation unit. A preloading method characterized by applying. A piezoelectric element that expands and contracts in response to an applied voltage;
A displacement enlarging mechanism for enlarging the expansion / contraction displacement of the piezoelectric element and causing the expanded displacement to act on an object, wherein the displacement enlarging mechanism is applied to one end and the other end in the expansion / contraction direction of the piezoelectric element. A preloading method in a piezoelectric actuator for applying a compressive force to the piezoelectric element in a piezoelectric actuator having two abutting portions in contact with each other,
In a state where the piezoelectric element is not attached, the length between the two contact portions is made shorter than the length in the expansion / contraction direction of the piezoelectric element,
A preloading method, wherein when assembling the piezoelectric element and the displacement enlarging mechanism, the piezoelectric element is inserted between the two contact portions so as to exert a compressive force on the piezoelectric element.

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