JP5614026B2 - Actuator - Google Patents

Description

  The present invention relates to an actuator, and more particularly, to an actuator including a sheet formed of a polymer electrostrictive material.

  There are increasing opportunities for actuators to be used in devices that require precise movement, such as medical devices and industrial robots. As opportunities for use increase, there is an urgent need to develop actuators that are small in size and large in displacement. For example, Patent Document 1 discloses an actuator having a small size and a large displacement by laminating piezoelectric ceramic materials such as PZT (lead zirconate titanate).

  The actuator disclosed in Patent Document 1 includes three sets of actuator members in which piezoelectric ceramic materials are laminated, and the three sets of actuator members are coupled with each other so as to be in series with each other. Therefore, the actuator disclosed in Patent Document 1 has a larger displacement than an actuator of the same size using one set of actuator members.

JP-A-3-22869

  The actuator disclosed in Patent Document 1 has a problem in that it cannot be manufactured at low cost because it requires a complicated operation of joining three sets of actuator members with a connecting member. In addition, since the actuator member disclosed in Patent Document 1 constitutes the framework of the actuator, a polymer electrostrictive material such as PVDF (polyvinylidene fluoride) can be used for the actuator member. First, it was necessary to use a hard piezoelectric ceramic material. Therefore, the actuator disclosed in Patent Document 1 has a problem that it cannot use a light polymer electrostrictive material as compared with a piezoelectric ceramic material, and cannot be reduced in weight.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an actuator that can be reduced in weight and that is small in size and large in displacement. Another object of the present invention is to provide an actuator that can be manufactured at low cost because it is assembled only by simple work.

  In order to achieve the above object, an actuator according to a first invention includes a sheet formed of a polymer electrostrictive material, electrode films formed on the front and back surfaces of the sheet at predetermined intervals, and the sheet. A reinforcing member having an elastic modulus equal to or higher than the elastic modulus of the sheet, and alternately formed with the electrode film on at least one surface of the sheet, and bending the sheet into a bellows shape, and the electrode film and the reinforcing member Are stacked alternately.

  According to a second aspect of the present invention, there is provided an actuator according to the first aspect, further comprising a pulling means for applying a predetermined tension in the long side direction of the sheet to at least each of the portions of the sheet on which the electrode film is formed. .

  The actuator according to a third invention is the actuator according to the first or second invention, wherein the reinforcing member is polyethylene terephthalate, polyacetal, polyamide, polycarbonate, modified polyphenylene ether, polybutylene terephthalate, amorphous polyarylate, polysulfone, polyethersulfur. It is made of any of phon, polyphenylene sulfide, polyether ether ketone, polyimide, polyether imide, fluororesin, and liquid crystal polymer.

  According to a fourth aspect of the present invention, there is provided the actuator according to the first or second aspect, wherein the reinforcing member is formed by increasing the thickness of the sheet as compared with the thickness of the sheet where the electrode film is formed. To do.

  In the first invention, in the actuator including the sheet, the electrode film, and the reinforcing member, the sheet is formed into an electrode film by bending the sheet into a bellows shape and alternately laminating the electrode film and the reinforcing member. The elongation of each of these portions is accumulated, and the displacement becomes larger than that of an actuator of the same size that is used without bending the sheet on which the electrode film is formed. In the first aspect of the invention, the sheet can be assembled by a simple operation such as folding the sheet into a bellows shape, and the sheet can be manufactured at low cost, and the size can be reduced because the sheet is folded into a bellows shape. Furthermore, in the first invention, since a sheet formed of a polymer electrostrictive material is used, the weight can be reduced as compared with an actuator using a piezoelectric ceramic material.

  In the second invention, since at least each portion of the sheet on which the electrode film is formed is provided with tension means for applying a predetermined tension in the long side direction of the sheet, the sheet is displaced even when the sheet is thin. The actuator can be made smaller and lighter.

  In the third invention, the reinforcing member is made of polyethylene terephthalate, polyacetal, polyamide, polycarbonate, modified polyphenylene ether, polybutylene terephthalate, amorphous polyarylate, polysulfone, polyether sulfone, polyphenylene sulfide, polyether ether ketone, polyimide, poly Since it is formed of any of ether imide, fluororesin, and liquid crystal polymer, the member to be reinforced can be reduced in weight so that the shape of the sheet can be maintained, and the actuator itself can be reduced in weight.

  In the fourth invention, since the reinforcing member is formed by increasing the thickness of the sheet as compared with the thickness of the sheet in which the electrode film is formed, the sheet itself has strength in the portion where the reinforcing member is formed. Thus, the reinforcing member can be configured, and there is no need to prepare a separate material for the reinforcing member.

  The actuator according to the present invention is an actuator including a sheet, an electrode film, and a reinforcing member. The electrode film is formed by alternately laminating the electrode film and the reinforcing member by bending the sheet into a bellows shape. The elongation of each part of a certain sheet is accumulated, and the displacement becomes larger than that of an actuator of the same size that is used without bending the sheet on which the electrode film is formed. Further, since the sheet is assembled by only a simple operation such as folding the sheet into a bellows shape, the sheet can be manufactured at a low cost, and the sheet can be folded into a bellows shape, thereby reducing the size. Furthermore, since a sheet formed of a polymer electrostrictive material is used, the weight can be reduced compared to an actuator using a piezoelectric ceramic material.

It is sectional drawing which shows typically the structure of the actuator which concerns on embodiment of this invention. It is sectional drawing which shows typically the means to maintain the shape of the actuator which concerns on embodiment of this invention. It is sectional drawing which shows typically another means to maintain the shape of the actuator which concerns on embodiment of this invention. It is sectional drawing which shows typically the tension means of the actuator which concerns on embodiment of this invention. It is a perspective view which shows typically the manufacturing method of the actuator which concerns on embodiment of this invention. It is a perspective view which shows typically the manufacturing method of the actuator which concerns on embodiment of this invention.

  Hereinafter, an actuator according to an embodiment of the present invention will be specifically described with reference to the drawings. The following embodiments do not limit the invention described in the claims, and all combinations of characteristic items described in the embodiments are essential to the solution. It goes without saying that it is not limited.

  FIG. 1 is a cross-sectional view schematically showing a configuration of an actuator according to an embodiment of the present invention. As shown in FIG. 1, the actuator 1 includes an electrostrictive sheet (sheet) 2 bent into a bellows shape, an electrode film 3 formed on the front and back surfaces of the electrostrictive sheet 2 at a predetermined interval, Reinforcing members 4 formed alternately with the electrode films 3 are provided on the front and back surfaces of the strain sheet 2.

  The electrostrictive sheet 2 is not particularly limited as long as the electrostrictive sheet 2 is made of a polymer electrostrictive material and has a ferroelectric polymer property. For example, PVDF (polyvinylidene fluoride), PVDF (polyvinylidene fluoride) -based copolymer PVDF-TrFE, or PVDF-based terpolymers, such as PVDF-TrFE-CFE, PVDF-TrFE-CTFE, PVDF-TrFE-CDFE, PVDF-TrFE-HFA, PVDF-TrFE-HFP, PVDF-TrFE-VC and the like are preferable. TrFE is trifluoroethylene, CFE is chlorofluoroethylene, CTFE is chlorotrifluoroethylene, CDFE is chlorodifluoroethylene, HFA is hexafluoroacetone, HFP is hexafluoropropylene, and VC is vinyl chloride. Respectively.

  Specifically, as the electrostrictive sheet 2, one sheet having a thickness of several μm to 100 μm is formed using the above-described polymer electrostrictive material. Ni (nickel), Pt (platinum), Pt-Pd (platinum-palladium alloy), Al (aluminum), Au (gold), Au-Pd (gold-palladium) are formed on both surfaces of the electrostrictive sheet 2 by vapor deposition or sputtering. A metal film such as an alloy is formed as the electrode film 3. The electrode film 3 has a thickness of about 20 nm to 50 nm.

  The reinforcing member 4 is a member that reinforces the electrostrictive sheet 2 so that the shape of the electrostrictive sheet 2 can be maintained, and is formed of a material having an elastic modulus equal to or higher than the elastic modulus of the electrostrictive sheet 2, for example, a polyethylene terephthalate (PET) plate. The reinforcing member 4 is composed of polyacetal (POM), polyamide (PA), polycarbonate (PC), modified polyphenylene ether (m-PPE), polybutylene terephthalate (PBT), amorphous polyarylate (PAR), polysulfone (PSF), poly Even engineering plastics such as ether sulfone (PES), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyimide (PI), polyetherimide (PEI), fluororesin, and liquid crystal polymer (LCP) good. The reinforcing member 4 can be formed on the electrostrictive sheet 2 by sticking the PET plate to the electrostrictive sheet 2 using an epoxy thermosetting adhesive or a UV curable adhesive. The position where the reinforcing member 4 is attached is between the electrode film 3 and the electrode film 3 formed on the electrostrictive sheet 2 at a predetermined interval. The electrode film 3 and the reinforcing member 4 are alternately arranged on the electrostrictive sheet 2. It is formed. The reinforcing member 4 is not limited to being formed on both the front and back surfaces of the electrostrictive sheet 2, and may be formed on one surface of the electrostrictive sheet 2. Further, the present invention is not limited to the case where the reinforcing member 4 is formed by adhering the PET plate to the electrostrictive sheet 2 using an epoxy-based thermosetting adhesive or UV curing adhesive. The electrostrictive sheet 2 itself may be made thicker than the electrostrictive sheet 2 so that the electrostrictive sheet 2 itself has strength and functions as the reinforcing member 4.

  The electrostrictive sheet 2 is bent into a bellows shape, and the electrode films 3 and the reinforcing members 4 are alternately stacked. Since the laminated reinforcing members 4 are connected to each other as described later, the movement of the reinforcing member 4 is restricted, and the movement of one reinforcing member 4 affects the other reinforcing members 4. Accordingly, the reinforcing member 4 easily moves in the direction in which the electrostrictive sheet 2 extends, but hardly moves in directions other than the extending direction, and as a result, moves only in one direction. Further, when the electrostrictive sheet 2 is extended and the reinforcing member 4 directly connected to the extended electrostrictive sheet 2 is moved, the other reinforcing members 4 are also moved.

  The actuator 1 needs to maintain a shape in which the electrostrictive sheet 2 is bent into a bellows shape and the electrode films 3 and the reinforcing members 4 are alternately laminated. Specifically, the means for maintaining the shape of the actuator 1 will be described in detail. FIG. 2 is a cross-sectional view schematically showing a means for maintaining the shape of the actuator 1 according to the embodiment of the present invention. 2 is a cross-sectional view taken along the line AA of the actuator 1 shown in FIG. As shown in FIG. 2, the actuator 1 includes a housing 5, and the shape of the actuator 1 is maintained by the housing 5. That is, the electrostrictive sheet 2 on which the electrode film 3 is formed expands and contracts so that it is not held in the casing 5 and the reinforcing member 4 can be moved in the direction in which the electrostrictive sheet 2 extends. By holding on the rail portion 5a, the reinforcing members 4 are joined together, and the shape of the actuator 1 is maintained. By holding each reinforcing member 4 on the rail portion 5a, it is possible to move along the rail portion 5a in a direction perpendicular to the paper surface of FIG. 2 (direction in which the electrostrictive sheet 2 extends).

  The means for maintaining the shape of the actuator 1 is not limited to the case where the housing 5 is provided. For example, FIG. 3 is a cross-sectional view schematically showing another means for maintaining the shape of the actuator 1 according to the embodiment of the present invention. 3 is a cross-sectional view taken along the line AA of the actuator 1 shown in FIG. As shown in FIG. 3, the actuator 1 does not include the housing 5, and has a reinforcing member 4 and an arm 4 a for connecting the other reinforcing member 4. The shape of the actuator 1 can be maintained without providing the housing 5 by joining the reinforcing members 4 using the arm 4a. Further, the arm 4a has a rail portion 4b that fits with the end portion of the reinforcing member 4, and the end portion of the reinforcing member 4 and the rail portion 4b are fitted to each other so that each reinforcing member 4 is connected to the rail portion. It is possible to move along the line 4b in the direction perpendicular to the plane of FIG. 3 (the direction in which the electrostrictive sheet 2 extends).

  Note that the arm 4a of the reinforcing member 4 located on the left side of the paper surface of FIG. 3 sequentially couples the other reinforcing members 4 located on the right side of the paper surface of FIG. It is not limited to the structure which couple | bonds together, In the structure which the arm 4a of the reinforcement member 4 located in the right side of the paper surface of FIG. 3 couple | bonds the other reinforcement member 4 located in the left side of the paper surface of FIG. There may be.

  Next, the operation of the actuator 1 according to the embodiment of the present invention will be described. In order to simplify the description, the actuator 1 shown in FIG. 1 includes a first layer 11, a second layer 12, a third layer 13, a fourth layer 14, a fifth layer 15, and a sixth layer in order from the left side of FIG. It is assumed that it is composed of seven layers of layer 16 and seventh layer 17. Of the seven layers, the first layer 11, the third layer 13, the fifth layer 15, and the seventh layer 17 include the portion of the electrostrictive sheet 2 on which the electrode film 3 is formed. The fourth layer 14 and the sixth layer 16 include a portion of the electrostrictive sheet 2 on which the reinforcing member 4 is formed.

  When a voltage is applied to the electrode film 3, the electrostrictive sheet 2 contracts in the vertical direction of the electrode film 3 and deforms so as to extend in the horizontal direction of the electrode film 3. Therefore, the first layer 11, the third layer 13, and the fifth layer The electrostrictive sheet 2 of the 15th and 17th layers 17 extends in the horizontal direction of the electrode film 3 (downward on the paper surface of FIG. 1). Here, it is assumed that the end portion 21 of the electrostrictive sheet 2 of the first layer 11 is fixed to the housing 5 (not shown) or the like.

  When a voltage is applied to the electrode film 3 of the first layer 11, the electrostrictive sheet 2 of the first layer 11 extends in the direction of the arrow 11a, and the second layer 12 that is directly connected to the electrostrictive sheet 2 of the first layer 11 is reinforced. The member 4 also moves in the direction of the arrow 11a, and the reinforcing members 4 of the fourth layer 14 and the sixth layer 16 coupled to the reinforcing member 4 of the second layer 12 also move in the direction of the arrow 11a. Similarly, when a voltage is applied to the electrode film 3 of the third layer 13, the electrostrictive sheet 2 of the third layer 13 extends in the direction of the arrow 13 a and the fourth layer is directly connected to the electrostrictive sheet 2 of the third layer 13. The reinforcing member 4 of 14 also moves in the direction of the arrow 13a, and the reinforcing member 4 of the sixth layer 16 coupled to the reinforcing member 4 of the fourth layer 14 also moves in the direction of the arrow 13a. When a voltage is applied to the electrode film 3 of the fifth layer 15, the electrostrictive sheet 2 of the fifth layer 15 extends in the direction of the arrow 15 a, and the sixth layer 16 is directly connected to the electrostrictive sheet 2 of the fifth layer 15. The reinforcing member 4 also moves in the direction of the arrow 15a. Furthermore, when a voltage is applied to the electrode film 3 of the seventh layer 17, the electrostrictive sheet 2 of the seventh layer 17 also extends in the direction of the arrow 17a.

  The electrostriction of each of the first layer 11, the third layer 13, the fifth layer 15, and the seventh layer 17 is caused by the movement of the reinforcing members 4 of the second layer 12, the fourth layer 14, and the sixth layer 16. The elongation of the sheet 2 is accumulated, and the end portion 22 of the electrostrictive sheet 2 of the seventh layer 17 is displaced to a position where the elongation is accumulated. The magnitude | size which the edge part 22 displaces to the direction of the arrow 22a becomes about 4 times compared with the actuator of the same size using only the electrostrictive sheet 2 of the 1st layer 11. FIG. That is, when the electrostrictive sheets 2 of the first layer 11, the third layer 13, the fifth layer 15, and the seventh layer 17 are displaced by about 3%, the actuator 1 according to the embodiment of the present invention is about 12%. Can be displaced. Furthermore, by bending the electrostrictive sheet 2 into a bellows shape and increasing the number of the electrode films 3 and the reinforcing members 4 stacked, the displacement of the end portion 22 can be further increased.

  Note that if the electrostrictive sheet 2 is thin, even if a voltage is applied to the electrode film 3, there is a case where the elongation cannot be taken out as a displacement. In this case, in order to take out the elongation of the electrostrictive sheet 2 as a displacement, at least for each portion of the electrostrictive sheet 2 on which the electrode film 3 is formed in a state where no voltage is applied to the electrode film 3. Thus, it is necessary to apply a predetermined tension in the long side direction of the electrostrictive sheet 2. That is, the actuator 1 needs to further include tension means for applying a predetermined tension in the long side direction of the electrostrictive sheet 2.

  FIG. 4 is a cross-sectional view schematically showing tension means of the actuator 1 according to the embodiment of the present invention. As shown in FIG. 4, an elastic body 41 (for example, a spring) is provided between the housing 5 and each reinforcing member 4. The elastic body 41 is installed in each reinforcing member 4 in a contracted state, whereby a force that pushes each reinforcing member 4 downward in FIG. 4 acts, and the electrostrictive sheet 2 directly connected to each reinforcing member 4. On the other hand, a predetermined tension can be applied in the long side direction of the electrostrictive sheet 2. The elastic body 41 is disposed so that a predetermined tension is applied to each portion of the electrostrictive sheet 2 on which the electrode film 3 is formed.

  The pulling means is not limited to the configuration in which the elastic body 41 is provided between the casing 5 and each reinforcing member 4, and at least for each portion of the electrostrictive sheet 2 on which the electrode film 3 is formed. As long as a predetermined tension can be applied in the long side direction of the electrostrictive sheet 2, another configuration may be used. For example, a method of applying a predetermined tension in the long side direction of the electrostrictive sheet 2 by applying a load in the direction of the arrow 22b at the end portion 22 shown in FIG.

  Next, a method for manufacturing the actuator 1 according to the embodiment of the present invention will be described. 5 and 6 are perspective views schematically showing the manufacturing method of the actuator 1 according to the embodiment of the present invention. As shown in FIG. 5, an electrostrictive sheet 2 is prepared, and a metal film such as Ni (nickel) is formed as an electrode film 3 on both the front and back surfaces of the prepared electrostrictive sheet 2 by vapor deposition or sputtering. Four electrode films 3 are formed on the electrostrictive sheet 2 at predetermined intervals. This is to form an actuator 1 in which four layers of the electrostrictive sheet 2 on which the electrode film 3 is formed, like the actuator 1 shown in FIG. If the actuator 1 is formed by further laminating the strain sheet 2 portions, it is necessary to form a large number of electrode films 3 on the electrostrictive sheet 2 at a predetermined interval.

  As shown in FIG. 6, the reinforcing member 4 is formed by attaching a PET plate to both the front and back surfaces of the electrostrictive sheet 2 on which the electrode film 3 is formed, using an epoxy thermosetting adhesive or the like. Three reinforcing members 4 are formed on the electrostrictive sheet 2 between the electrode films 3. As the number of the electrode films 3 increases, the number of portions of the electrostrictive sheet 2 between the electrode films 3 and the electrode films 3 also increases, and the number of reinforcing members 4 to be formed also increases.

  The electrostrictive sheet 2 on which the electrode film 3 and the reinforcing member 4 are formed is bent into a bellows shape to form the actuator 1 in which the electrode films 3 and the reinforcing members 4 are alternately stacked. The actuator 1 in which the electrode films 3 and the reinforcing members 4 are alternately laminated is configured as shown in FIG. 1, and the laminated reinforcing members 4 can move in a predetermined direction as shown in FIG. 2 or FIG. To join.

  As described above, the actuator 1 according to the embodiment of the present invention includes the electrostrictive sheet 2, the electrode film 3, and the reinforcing member 4, and the electrostrictive sheet 2 is bent into a bellows shape, By alternately laminating the reinforcing members 4, the elongation of each portion of the electrostrictive sheet 2 on which the electrode film 3 is formed is accumulated, and the same size using only the electrostrictive sheet 2 of the first layer 11. The displacement is larger than that of the actuator. Moreover, since it assembles only by simple operations, such as bending the electrostrictive sheet 2 into a bellows shape, it can manufacture at low cost, and since the electrostrictive sheet 2 is bent into a bellows shape, the size can be reduced. Furthermore, since the electrostrictive sheet 2 formed of a polymer electrostrictive material is used, the weight can be reduced compared to an actuator using a piezoelectric ceramic material.

DESCRIPTION OF SYMBOLS 1 Actuator 2 Electrostrictive sheet 3 Electrode film 4 Reinforcement member 4a Arm 4b, 5a Rail part 5 Housing | casing 21,22 End part 41 Elastic body (tensile means)

Claims (4)

A sheet formed of a polymer electrostrictive material;
Electrode films formed on the front and back surfaces of the sheet at predetermined intervals;
A reinforcing member having an elastic modulus equal to or higher than the elastic modulus of the sheet, and being formed alternately with the electrode film on at least one surface of the sheet,
An actuator, wherein the sheet is bent into a bellows shape and the electrode films and the reinforcing members are alternately stacked.   2. The actuator according to claim 1, further comprising tension means for applying a predetermined tension in a long side direction of the sheet to at least each of the sheet portions on which the electrode film is formed.   The reinforcing member is polyethylene terephthalate, polyacetal, polyamide, polycarbonate, modified polyphenylene ether, polybutylene terephthalate, amorphous polyarylate, polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyimide, polyetherimide, fluorine. The actuator according to claim 1, wherein the actuator is formed of a resin or a liquid crystal polymer.   3. The actuator according to claim 1, wherein the reinforcing member is configured by increasing a thickness of the sheet as compared with a thickness of the sheet in a portion where the electrode film is formed.

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