JP5486156B2 - Dielectric film for actuator and actuator using the same - Google Patents

Description

  The present invention relates to a dielectric film for an actuator that expands and contracts by a change in applied voltage, and an actuator using the same.

In the fields of industrial and nursing robots, medical equipment, micromachines, and the like, there is an increasing need for highly flexible, small, and lightweight actuators. As such an actuator material, for example, various polymers such as a conductive polymer, an ion conductive polymer (ICPF), and a dielectric elastomer have been proposed. In particular, an actuator using a dielectric elastomer is useful because it can be easily miniaturized and manufactured at low cost. For example, Patent Documents 1 and 2 introduce an actuator in which a dielectric film made of a dielectric elastomer is held between a pair of electrodes.
Special table 2003-506858 JP-T-2001-524278

  In the actuator, when the voltage applied between the electrodes is increased, the electrostatic attractive force between the electrodes is increased. For this reason, the dielectric film sandwiched between the electrodes is compressed from the film thickness direction, and the film thickness of the dielectric film is reduced. As the film thickness decreases, the dielectric film extends in a direction parallel to the electrode surface. Further, when the voltage applied between the electrodes is reduced, the electrostatic attractive force between the electrodes is reduced. For this reason, the compressive force from the film thickness direction to the dielectric film is reduced, and the film thickness is increased by the elastic restoring force of the dielectric film. As the film thickness increases, the dielectric film shrinks in the direction parallel to the electrode surface. Thus, the actuator drives the member to be driven by extending and contracting the dielectric film.

  The actuator is required to have a large output force and displacement. As shown in Patent Documents 1 and 2, acrylic rubber, silicone rubber, fluorine rubber, nitrile rubber, and the like are used as the dielectric film of the actuator. However, these conventional materials cannot satisfy both force and displacement. For example, acrylic rubber has a small Young's modulus. For this reason, acrylic rubber is soft, and the force obtained when used as a dielectric film is small. Further, since the creep is large, there is a problem in durability.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a dielectric film that can output a large force and obtain a large amount of displacement when an actuator is configured. It is another object of the present invention to provide an actuator having a large force and displacement by using such a dielectric film.

(1) In order to solve the above problems, the actuator dielectric film of the present invention is interposed between a plurality of electrodes, expands and contracts due to a change in voltage applied between the plurality of electrodes, and has a crosslinking density of 5. It consists of a nitrile rubber of 49 × 10 ⁻⁶ mol / cm ³ or more (corresponding to claim 1).

  Nitrile rubber is made of acrylonitrile-butadiene copolymer rubber (NBR), hydrogenated nitrile rubber (H-NBR), NBR modified by introducing a third monomer, and a blend material of these with vinyl chloride (PVC) or the like. Including. Nitrile rubber has a large dielectric constant because it has a nitrile group which is a polar group. For example, the dipole moment of NBR is about twice that of acrylic rubber. For this reason, when used as a dielectric film in the same electric field, a large force can be output as compared with acrylic rubber.

Here, the dielectric film for an actuator of the present invention (hereinafter referred to as “the dielectric film of the present invention” as appropriate) is made of a nitrile rubber having a crosslink density of 5.49 × 10 ⁻⁶ mol / cm ³ or more. Since the crosslinking density is higher than that of conventional NBR, the Young's modulus of nitrile rubber (dielectric film) is large. That is, the strength of nitrile rubber is large. For this reason, when an actuator is comprised using the dielectric film of this invention, a bigger force can be output. Moreover, since the crosslinking density is large, the dielectric breakdown strength of nitrile rubber is large. For this reason, it becomes possible to apply a higher voltage and to obtain a larger displacement. Furthermore, the dielectric film of the present invention is difficult to creep and has a long life. Therefore, according to the dielectric film of the present invention, the durability of the actuator is improved.

(2) The actuator of the present invention includes a dielectric film and a plurality of electrodes arranged via the dielectric film, and the dielectric film has a crosslink density of 5.49 × 10 ^−6. It consists of nitrile rubber of mol / cm ³ or more (corresponding to claim 6).

  The actuator of the present invention includes the dielectric film of the present invention. For this reason, according to the actuator of the present invention, a large force can be obtained, and a larger displacement can be obtained by applying a high voltage. Further, since the dielectric breakdown strength is large and the lifetime of the dielectric film is long, the actuator of the present invention has high durability.

Hereinafter, the dielectric film for an actuator of the present invention and the actuator using the same will be described in detail.
1. Dielectric film The dielectric film of the present invention comprises a nitrile rubber having a crosslink density of 5.49 × 10 ⁻⁶ mol / cm ³ or more. As described above, examples of the nitrile rubber include NBR, H-NBR, modified NBR, and blend materials of these with PVC and the like. Among these, one or more selected from NBR and H-NBR are preferable. Here, since H-NBR has fewer double bonds than NBR, the electrical resistance is large. For this reason, the dielectric breakdown strength is high, and a higher voltage can be applied. That is, when H-NBR is adopted as the nitrile rubber, a larger displacement can be easily obtained when the actuator is configured.

  Further, the amount of bound acrylonitrile (bound AN amount) of the nitrile rubber is desirably 18% by weight or more. The amount of bonded AN is the weight ratio of the acrylonitrile contained when the total weight of the rubber is 100% by weight. The greater the amount of combined AN, the greater the strength. Therefore, a larger force can be output when the actuator is configured. More preferably, the amount of bonded AN is 35% by weight or more, and further 40% by weight or more. The amount of bonded AN can be determined, for example, by decomposing nitrile rubber with concentrated sulfuric acid, adding a sodium hydroxide solution, and quantifying the generated ammonia.

The crosslinking density of the nitrile rubber is 5.49 × 10 ⁻⁶ mol / cm ³ or more. From the viewpoint of increasing the Young's modulus, the dielectric breakdown strength, and the like, it is more preferable that the crosslink density is 9.09 × 10 ⁻⁵ mol / cm ³ or more. In this specification, the following method is employ | adopted as a measuring method of a crosslinking density. First, a nitrile rubber sample (thickness 1.0 ± 0.1 mm) is Soxhlet extracted at 80 ° C. for 15 hours, air-dried with cold air, and then vacuum-dried at room temperature for 15 hours. Next, the treated sample was formed into a size of length 2.0 ± 0.1 mm × width 2.0 ± 0.1 mm × thickness 1.0 ± 0.1 mm, and toluene / tetrahydrofuran (volume ratio 1: 1) Swell with 2 ml of solution (15 hours at room temperature). The dimensional change before and after swelling and the dimensional change when a load is applied are measured, and the crosslinking density is calculated using the theoretical formula of Flory-Rhener.

  Such a nitrile rubber is prepared by adding a crosslinking agent, a vulcanization accelerator, a processing aid, a plasticizer, an anti-aging agent, a colorant and the like to a raw material polymer as necessary. The nitrile rubber composition may be produced by crosslinking. For example, what is necessary is just to manufacture as follows. As a first method, first, a nitrile rubber composition is prepared by adding a kneading agent and a processing aid to a raw material polymer and kneading them. Next, the prepared nitrile rubber composition is molded, filled in a mold, and press-crosslinked under predetermined conditions. Further, the nitrile rubber composition prepared in the same manner as in the first method may be cross-linked after being extruded into a film or tube. As a second method, first, the raw material polymer is dissolved in a predetermined solvent. A nitrile rubber composition is prepared by adding a crosslinking agent or the like to the solution, stirring and mixing. Next, the prepared nitrile rubber composition is applied onto a substrate, dried to evaporate the solvent, and then crosslinked.

  Here, as the crosslinking agent, it is desirable to use one or more selected from sulfur and organic peroxides. In particular, when an organic peroxide is used, the remaining amount of impurities is small. For this reason, the electrical resistance of the nitrile rubber is increased, and the dielectric breakdown strength can be further increased.

  Examples of the organic peroxide include dicumyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-di (t- Butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxyisopropyl) hexyne-3, and the like. When using an organic peroxide (peroxide crosslinking), from the viewpoint of increasing the crosslinking density, the amount of the crosslinking agent is set to 100 parts by weight of the rubber component (raw polymer) before crosslinking of the nitrile rubber. It is desirable that the amount be 2.4 parts by weight or more. 4.8 parts by weight or more is more preferable. On the other hand, if the amount of the cross-linking agent is too large, the Young's modulus increases and becomes hard, so that it tends to break when used as a dielectric film. For this reason, the amount of the crosslinking agent is desirably 9.6 parts by weight or less. It is more preferable that the amount is 7.2 parts by weight or less. In addition, the said compounding quantity is a value when the organic peroxide component of a crosslinking agent is 100%.

  When sulfur is used as the cross-linking agent (sulfur cross-linking), from the viewpoint of increasing the cross-linking density as described above, the amount of the cross-linking agent is set to 100 weight parts of the nitrile rubber pre-crosslinking rubber component (raw polymer). It is desirable to be 0.44 parts by weight or more with respect to parts. It is more suitable when it is 0.88 parts by weight or more. On the other hand, as described above, if the amount of the cross-linking agent is too large, the Young's modulus increases, so that it tends to break when used as a dielectric film. For this reason, it is desirable that the amount of the crosslinking agent is 2.2 parts by weight or less. It is more suitable when it is 1.8 parts by weight or less.

When an actuator is configured using the dielectric film of the present invention, a plurality of electrodes may be disposed with the dielectric film of the present invention interposed therebetween. The dielectric film of the present invention expands and contracts due to a change in voltage applied between the plurality of electrodes. Hereinafter, an actuator using the dielectric film of the present invention, that is, an embodiment of the actuator of the present invention will be described.
2. Actuator <First embodiment>
FIG. 1 is a schematic cross-sectional view of the actuator of this embodiment. (A) shows an OFF state, and (b) shows an ON state. As shown in FIG. 1, the actuator 1 includes a dielectric film 20 and electrodes 21a and 21b. The dielectric film 20 is made of a nitrile rubber having a crosslink density of 5.49 × 10 ⁻⁶ mol / cm ³ or more. The electrodes 21a and 21b are fixed to the front and back of the dielectric film 20, respectively. The electrodes 21a and 21b are connected to the power source 22 through conductive wires. When switching from the off state to the on state, a voltage is applied between the pair of electrodes 21a and 21b. As the voltage is applied, the thickness of the dielectric film 20 is reduced, and as much as that, the dielectric film 20 extends in a direction parallel to the surfaces of the electrodes 21a and 21b, as indicated by white arrows in FIG. Thereby, the actuator 1 outputs the driving force in the horizontal direction in the figure.

  The dielectric film 20 is made of nitrile rubber having a high crosslinking density. Since the strength of the dielectric film 20 is large, the output of the actuator 1 is large. Moreover, since the dielectric breakdown strength of the dielectric film 20 is high, a higher voltage can be applied and a large displacement can be obtained. Furthermore, the dielectric film 20 is difficult to creep and has a long life. For this reason, the actuator 1 is excellent in durability.

  Also in the actuator of the present invention, it is desirable to adopt the above-described preferred embodiment of the dielectric film of the present invention. Further, the thickness of the dielectric film may be appropriately determined according to the use of the actuator. For example, the thickness of the dielectric film is desirably thinner from the viewpoints of downsizing the actuator, driving at a low potential, and increasing the amount of displacement. In this case, it is desirable that the thickness of the dielectric film be 1 μm or more and 1000 μm (1 mm) or less in consideration of dielectric breakdown properties and the like. A more preferable range is 5 μm or more and 200 μm or less. Moreover, when the dielectric film of the present invention is attached in a state extending in the surface extending direction, the dielectric breakdown strength of the dielectric film is improved, and a larger displacement amount can be obtained.

  The material of the electrode is not particularly limited. For example, an electrode obtained by applying a paste or paint in which oil or elastomer is mixed as a binder to a conductive material made of a carbon material such as carbon black or carbon nanotube or a metal can be used. It is desirable that the electrode can expand and contract according to the expansion and contraction of the dielectric film. When the electrode expands and contracts together with the dielectric film, the deformation of the dielectric film is not easily disturbed by the electrode, and a desired amount of displacement is easily obtained.

  Further, when a laminated structure in which a plurality of dielectric films and electrodes are alternately laminated, a larger force can be generated. As a result, the output of the actuator is increased, and the driven member can be driven with a greater force.

<Second embodiment>
[Configuration of actuator]
First, the configuration of the actuator of this embodiment will be described. FIG. 2 is a perspective view of the actuator of this embodiment. FIG. 3 shows an exploded perspective view of the actuator. FIG. 4 shows an axial sectional view of the actuator. 2 to 4, parts corresponding to those in FIG. 1 are denoted by the same reference numerals.

  As shown in FIGS. 2 to 4, the actuator 1 includes an actuator element 2 and a weight 32.

  The actuator element 2 includes a telescopic member 24, an upper end member 33, and a lower end member 34. The elastic member 24 includes a dielectric film 240 and a pair of electrodes 241a and 241b. The elastic member 24 is interposed between the upper end member 33 and the lower end member 34. The dielectric film 240 has a hollow cylindrical shape (tube shape). The pair of electrodes 241 a and 241 b are disposed on the outer peripheral surface and the inner peripheral surface of the dielectric film 240. The pair of electrodes 241a and 241b are each connected to a power source (not shown).

  Of the pair of electrodes 241 a and 241 b, the electrode 241 b disposed on the inner peripheral side of the dielectric film 240 covers the entire inner peripheral surface of the dielectric film 240. The electrode 241b extends from the lower end portion of the inner peripheral surface of the dielectric film 240 to the lower end portion of the outer peripheral surface via the lower end surface.

  On the other hand, of the pair of electrodes 241 a and 241 b, the electrode 241 a disposed on the outer peripheral side of the dielectric film 240 covers an intermediate portion of the outer peripheral surface of the dielectric film 240. That is, at the upper end portion of the dielectric film 240, the outer peripheral electrode 241 a is disposed at a predetermined distance from the upper end member 33. In addition, at the lower end portion of the dielectric film 240, the outer electrode 241a is disposed at a predetermined distance from the electrode 241b connected to the inner periphery.

  The lower end of the wire 90 is inserted into the upper end inner diameter side of the elastic member 24. On the other hand, a ring-shaped upper end member 33 is fixed to the outer peripheral surface of the upper end of the elastic member 24 by caulking. The upper end member 33 suppresses the separation of the wire 90 and the elastic member 24. The upper end member 33 is fixed to an upper member (not shown) via the wire 90.

  The upper end of the weight 32 is inserted into the lower end inner diameter side of the elastic member 24. On the other hand, a ring-shaped lower end member 34 is fixed to the outer peripheral surface of the lower end of the elastic member 24 by caulking. The lower end member 34 prevents the weight 32 and the elastic member 24 from separating. The weight 32 applies a downward biasing force to the actuator element 2.

[Actuator manufacturing method]
Next, a method for manufacturing the actuator of this embodiment will be described. The manufacturing method of the actuator of this embodiment has an expansion-contraction member preparation process and an upper-lower-end member attachment process. In the elastic member manufacturing step, first, 100 parts by weight of raw material polymer H-NBR (“Zetpol (registered trademark) 0020” manufactured by Nippon Zeon Co., Ltd.) and processing aid stearic acid (“LUNAC (registered trademark) manufactured by Kao Corporation) are used. S30 ") 1 part by weight, sulfur as a crosslinking agent (" Sulfax T-10 "manufactured by Tsurumi Chemical Co., Ltd.) 0.88 part by weight, and zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd.) as a vulcanization accelerator 5 parts by weight Parts, 2.1 parts by weight of vulcanization accelerator tetraethylthiuram disulfide (“Sanseller (registered trademark) TET-G” manufactured by Sanshin Chemical Co., Ltd.), and N-cyclohexyl-2-benzothiazylsulfenamide (manufactured by the same company) 1 part by weight of “Sunceller CZ-G”) is kneaded with a roll kneader.

  Next, the kneaded product is passed through an extruder (the head portion is set at 100 ° C.) to form a tube having an inner diameter (diameter) of 1.6 mm and an outer diameter (diameter) of 2.0 mm. The tube is then vulcanized in an oven at 170 ° C. for 30 minutes. In this way, the dielectric film 240 is produced.

  Subsequently, a mixed solution of carbon black and elastomer is passed through the inner peripheral side of the dielectric film 240, and the solution is attached to the inner peripheral surface of the dielectric film 240. In addition, the same solution is applied to the outer peripheral surface of the dielectric film 240. At this time, a ring-shaped unpainted portion is secured near the lower end of the outer peripheral surface. Then, the lower portion of the unpainted portion is connected to the solution adhesion portion on the inner peripheral surface of the dielectric film 240. Thereafter, the dielectric film 240 is air-dried and heated in an oven at 170 ° C. for 30 minutes.

  In this manner, the electrode 241a is formed above the unpainted portion on the outer peripheral surface of the dielectric film 240, and the electrode 241b is formed below the unpainted portion on the inner peripheral surface and the outer peripheral surface of the dielectric film 240, respectively. 24 is completed.

  In the upper / lower end member attaching step, a weight (weight 50 g) 32 is connected to the lower end of the completed elastic member 24 (length: 200 mm) via the lower end member. Similarly, the wire 90 is connected to the upper end of the completed elastic member 24 via the upper end member 33. In this way, the manufacture and attachment of the actuator 1 are completed.

[Function and effect]
Next, the effect of the actuator of this embodiment is demonstrated. The actuator of the present embodiment has the same operational effects as the actuator of the first embodiment with respect to the parts having the same configuration.

  A voltage was applied to the electrodes 241a and 241b of the actuator 1 of the present embodiment, and the displacement amount of the weight 32 was measured. A voltage could be applied without breaking down to 7.5 kV at 1 Hz, and a large amount of displacement could be obtained. The actuator 1 and the dielectric film 240 of this embodiment are suitable as an artificial muscle, for example.

<Third embodiment>
In this embodiment, the actuator of the present invention is embodied as a pump.

[Pump configuration]
First, the configuration of the pump of this embodiment will be described. FIG. 5 shows a perspective view of the pump of this embodiment. FIG. 6 shows a sectional view in the exploded axial direction of the pump. FIG. 7 shows an exploded perspective view of the diaphragm member of the pump. FIG. 8 shows an axial sectional view of the pump in the off state. FIG. 9 shows an axial cross-sectional view of the pump in the on state.

  The pump 6 includes an operating housing member 60, a driving housing member 61, a diaphragm member 62, and a biasing member 63. As shown in FIGS. 8 and 9, the pump 6 constitutes a part of the heat source cooling circuit C. In the heat source cooling circuit C, a coolant is circulated.

  The operating housing member 60 is made of acrylic resin and has a bottomed cylindrical shape that opens downward. That is, the operation opening 600 is disposed at the lower end of the operation housing member 60. An operation fluid chamber 601 is defined inside the operation housing member 60. Further, a suction cylinder portion 602 and a discharge cylinder portion 603 project from the upper bottom wall of the operation housing member 60. The suction cylinder portion 602 and the discharge cylinder portion 603 are disposed to face each other by 180 ° with the center of the upper bottom wall interposed therebetween. Both the suction cylinder portion 602 and the discharge cylinder portion 603 have a short-axis cylindrical shape. A suction port 602 a is opened at the tip of the suction cylinder portion 602. The suction port 602a is connected to the downstream side of the suction side check valve V1 of the heat source cooling circuit C. A discharge port 603a is opened at the tip of the discharge tube portion 603. The discharge port 603a is connected to the upstream side of the discharge-side check valve V2 of the heat source cooling circuit C. A ring-shaped flange portion 604 is formed on the outer peripheral wall surface of the operating housing member 60. A bolt through hole 604 a extending in the vertical direction is formed in the flange portion 604. A pair of bolt through-holes 604a are arranged to face each other by 180 °.

  The drive housing member 61 is made of acrylic resin and has a cylindrical shape. A driving opening 610 is disposed at the upper end of the driving housing member 61. The driving housing member 61 and the actuating housing member 60 are opposed to each other in the vertical direction with the diaphragm member 62 and the biasing member 63 sandwiched between the driving opening 610 and the actuating opening 600. Has been placed. A ring-shaped flange portion 614 is formed on the outer peripheral wall surface of the drive housing member 61. A bolt through hole 614a extending in the vertical direction is formed in the flange portion 614. A pair of bolt through-holes 614a are arranged to face each other by 180 °. The pair of bolt through-holes 614a is disposed to face the pair of bolt through-holes 604a of the operating housing member 60 in the vertical direction. Bolts 615 pass through the bolt through holes 604a and 614a from below to above. A nut 616 is screwed to the penetrating end (upper end) of the bolt 615. By these bolts 615 and nuts 616, the flange portion 614 of the drive housing member 61 and the flange portion 604 of the actuating housing member 60 are connected.

  The diaphragm member 62 is formed by laminating a plus electrode 620, a minus electrode 621, and a dielectric film 622. The plus electrode 620 and the minus electrode 621 have a circular film shape. The plus electrode 620 and the minus electrode 621 are deformed together with the dielectric film 622 so as not to restrict expansion and contraction of the dielectric film 622. The plus electrode 620 is connected to the plus side of the power supply via the switch S. The minus electrode 621 is connected to the minus side of the power source.

  The dielectric film 622 has a circular film shape. The dielectric film 622 has a slightly larger diameter than the plus electrode 620 and the minus electrode 621. The dielectric film 622 is interposed between the plus electrode 620 and the minus electrode 621. That is, a voltage is applied to the dielectric film 622 by a pair of positive electrode 620 and negative electrode 621 adjacent in the vertical direction.

  The materials of the dielectric film 622, the plus electrode 620, and the minus electrode 621 are the same as in the second embodiment. The dielectric film 622 was formed into a film having a thickness of 0.2 mm by press-vulcanizing the kneaded material obtained by kneading the predetermined raw material. The plus electrode 620 and the minus electrode 621 were each formed into a film shape having a thickness of 10 μm by a bar coating method.

  The diaphragm member 62 covers the drive opening 610 of the drive housing member 61. The diaphragm member 62 is fastened and fixed to the outer peripheral surface of the drive housing member 61 by a clamp member 617.

  The urging member 63 is made of rubber and has a circular film shape. A hemispherical portion 630 that protrudes downward is formed at the center of the circle of the urging member 63. The biasing member 63 covers the operation opening 600 of the operation housing member 60. The urging member 63 is fastened and fixed to the outer peripheral surface of the operating housing member 60 by a clamp member 607.

[Assembly method of pump of this embodiment]
Next, a method for assembling the pump 6 of this embodiment will be briefly described. First, the diaphragm member 62 is fixed to the drive opening 610 of the drive housing member 61 using the clamp member 617. At this time, the diaphragm member 62 is fixed to the driving opening 610 in an extended state in which the outer peripheral edge is extended in the biaxial direction. The stretch rate of the diaphragm member 62 (see formula (1) described later) is 100%. Subsequently, the urging member 63 is fixed to the operation opening 600 of the operation housing member 60 by using the clamp member 607.

  Next, the opening 600 for operation (that is, the biasing member 63) and the opening 610 for driving (that is, the diaphragm member 62) are abutted from above and below. At this time, the diaphragm member 62 is pressed by the hemispherical portion 630 of the biasing member 63 and elastically deforms downward. On the other hand, the urging member 63 is pressed by the diaphragm member 62 and elastically deforms upward. Diaphragm member 62 and urging member 63 stop at a position where both elastic forces are balanced. Then, the flange 614 of the drive housing member 61 and the flange 604 of the actuating housing member 60 are connected by the bolt 615 and the nut 616.

  Thereafter, the suction port 602a of the suction cylinder part 602 is located downstream of the suction side check valve V1 of the heat source cooling circuit C, and the discharge port 603a of the discharge cylinder part 603 is located upstream of the discharge side check valve V2 of the heat source cooling circuit C. Connect to each side. In this way, the pump 6 of this embodiment is assembled.

[Movement of pump of this embodiment]
Next, the movement of the pump 6 of this embodiment will be described. In the off state, the switch S is opened. For this reason, no voltage is applied to the dielectric film 622 of the diaphragm member 62. Therefore, as shown in FIG. 8, the diaphragm member 62 includes an elastic force (upward) of the diaphragm member 62, an elastic force (downward) of the urging member 63, and the weight of the diaphragm member 62, the urging member 63, and the coolant. It stops at the position where it is balanced (downward).

  When the switch S is closed, the switch S is turned on, and the diaphragm member 62 expands in the film deployment direction. However, the outer peripheral portion of the diaphragm member 62 is sandwiched between the opening 600 for operation and the opening 610 for driving. Therefore, the diaphragm member 62 protrudes downward according to the extension by the elastic force of the biasing member 63, the diaphragm member 62, the biasing member 63, and the weight of the coolant. That is, as shown in FIG. 9, the diaphragm member 62 protrudes downward compared to the off state (FIG. 8). When the diaphragm member 62 protrudes downward, the volume of the working fluid chamber 601 increases accordingly. For this reason, the suction side check valve V1 is opened (the discharge side check valve V2 is closed), and the coolant flows into the working fluid chamber 601 from the heat source cooling circuit C through the suction port 602a.

  When the switch is opened again, the on state is switched to the off state. For this reason, the diaphragm member 62 moves back upward against the elastic force of the urging member 63, the diaphragm member 62, the urging member 63, and the weight of the coolant. Therefore, the volume of the working fluid chamber 601 is reduced. When the volume of the working fluid chamber 601 is reduced, the discharge-side check valve V2 is opened (the suction-side check valve V1 is closed), and from the working fluid chamber 601 to the heat source cooling circuit C via the discharge port 603a. In addition, the coolant flows out.

  As described above, the pump 6 according to the present embodiment causes the OFF state and the ON state to be alternately generated by repeatedly opening and closing the switch, and the coolant is circulated to the heat source cooling circuit C. The circulating coolant cools the heat source on the outlet side of the pump 6. The coolant that has become high temperature by heat exchange with the heat source is cooled by the radiator and returned to low temperature. The coolant that has returned to a low temperature flows into the pump 6 and cools the heat source again on the outlet side of the pump 6. In this way, the coolant circulates through the heat source cooling circuit C.

[Function and effect]
Next, the effect of the pump 6 of this embodiment is demonstrated. According to the pump 6 of the present embodiment, the driving force is extracted using the electrostrictive characteristics of the dielectric film 622. For this reason, compared with the case where driving force is taken out with a motor etc., power consumption can be made small. Further, noise during driving can be reduced.

  Moreover, according to the pump 6 of this embodiment, since the dielectric breakdown strength of the dielectric film 622 is large, a higher voltage can be applied and a larger displacement amount can be obtained. Further, since the strength of the dielectric film 622 is large, the output is also large. Specifically, a voltage could be applied without breakdown to 3.5 kV at 15 Hz, and a large discharge liquid amount could be obtained.

  Further, according to the pump 6 of this embodiment, the plus electrode 620 and the minus electrode 621 can be expanded and contracted so as not to restrict the expansion and contraction of the dielectric film 622. For this reason, it is easy to ensure a desired stroke.

  Next, the present invention will be described more specifically with reference to examples.

<Manufacture of dielectric film>
(1) Manufacture of H-NBR film Four types of H-NBR films were manufactured using an organic peroxide as a crosslinking agent and changing the blending amount. First, 100 parts by weight of the raw material polymer H-NBR (“Zetpol 1000L” manufactured by ZEON Corporation; amount of bonded AN = 44% by weight) and dicumyl peroxide (“PARK Mill (registered trademark) D-” manufactured by Nippon Oil & Fats Co., Ltd.) 40 ", organic peroxide component 40%) and 6 parts by weight were kneaded with a roll kneader to prepare an H-NBR composition. The prepared H-NBR composition was formed into a thin sheet, filled in a mold, and press-crosslinked at 150 ° C. for about 35 minutes to obtain an H-NBR film. The crosslinking density of the obtained H-NBR film was 5.49 × 10 ⁻⁶ mol / cm ³ . This H-NBR film was used as the H-NBR film of Example 1.

Next, only the blending amount of the crosslinking agent (dicumyl peroxide) was changed, and an H-NBR film was produced in the same manner as described above. The amount of the crosslinking agent blended was 12 parts by weight, 18 parts by weight, and 24 parts by weight. These H-NBR films were used as the H-NBR films of Example 2, Example 3, and Example 4 in order from the one with the smallest blending amount of the crosslinking agent. Moreover, the H-NBR film produced with the blending amount of the crosslinking agent being 3 parts by weight was used as the H-NBR film of Comparative Example 1. Table 1 shows the raw materials used, their blending amounts, crosslink density, and Young's modulus values for each H-NBR film. Table 1 shows the same for the NBR films (Examples 5 to 7) described later.

(2) Manufacture of NBR membranes Three types of NBR membranes were manufactured using sulfur as a cross-linking agent and changing the blending amount. First, 100 parts by weight of a raw polymer NBR (“Nipol (registered trademark) DN003” manufactured by Nippon Zeon Co., Ltd .; bound AN amount = 50% by weight) and 5% by weight of a vulcanization acceleration aid zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd.) Were kneaded with a roll kneader. Subsequently, 0.44 parts by weight of sulfur as a crosslinking agent ("Sulfax T-10" manufactured by Tsurumi Chemical Co., Ltd.) and tetraethylthiuram disulfide as a vulcanization accelerator ("Sunseller TET-G" manufactured by Sanshin Chemical Co., Ltd.) 2 , 1 part by weight, and 1 part by weight of N-cyclohexyl-2-benzothiazylsulfenamide ("Sunseller CZ-G" manufactured by the same company) are added, mixed and dispersed in a roll kneader, An NBR composition was prepared. The prepared NBR composition was formed into a thin sheet, filled in a mold, and press-crosslinked at 150 ° C. for about 18 minutes to obtain an NBR film. The resulting NBR film had a crosslink density of 1.26 × 10 ⁻⁴ mol / cm ³ . This NBR film was used as the NBR film of Example 5.

  Next, only the blending amount of the crosslinking agent (sulfur) was changed to 0.88 parts by weight and 2.2 parts by weight, and an NBR film was produced in the same manner as described above. These NBR films were used as the NBR films of Examples 6 and 7.

<Actuator evaluation>
Actuators were constructed using each manufactured film as a dielectric film, and the amount of displacement and force of the actuator were measured.

(1) Experimental apparatus and experimental method First, an experimental apparatus and an experimental method will be described. A dielectric film having a predetermined size was produced from each film of the example and the comparative example. Electrodes were formed on the upper and lower surfaces of the produced dielectric film by applying a conductive paste mixed with conductive carbon and oil to produce an actuator. Hereinafter, the manufactured actuator is referred to as an actuator of Examples 1 to 7 or Comparative Example 1 corresponding to the type of dielectric film. FIG. 10 shows a top view of the manufactured actuator. FIG. 11 is a cross-sectional view taken along the line XI-XI in FIG.

As shown in FIGS. 10 and 11, the actuator 3 includes a dielectric film 30 and a pair of electrodes 31a and 31b. The dielectric film 30 has a circular thin film shape with a diameter of 70 mm. The dielectric film 30 is disposed in a state of being stretched in the biaxial direction at a stretch rate of 100%. Here, the stretching ratio is a value calculated by the following equation (1).
Stretch rate (%) = {√ (S / S ₀ ) −1} × 100 (1)
[S ₀ : Dielectric film area before stretching (natural state), S: Dielectric film area after stretching]
The pair of electrodes 31a and 31b are arranged so as to face each other in the vertical direction with the dielectric film 30 interposed therebetween. The electrodes 31 a and 31 b have a circular thin film shape with a diameter of about 27 mm, and are arranged substantially concentrically with the dielectric film 30. A terminal portion 310a protruding in the diameter increasing direction is formed on the outer peripheral edge of the electrode 31a. The terminal portion 310a has a rectangular plate shape. Similarly, a terminal portion 310b projecting in the diameter increasing direction is formed on the outer peripheral edge of the electrode 31b. The terminal portion 310b has a rectangular plate shape. The terminal portion 310b is disposed at a position facing the terminal portion 310a by 180 °. Each of the terminal portions 310a and 310b is connected to the power source 4 through a conducting wire.

  When a voltage is applied between the electrodes 31a and 31b, an electrostatic attractive force is generated between the electrodes 31a and 31b, and the dielectric film 30 is compressed. As a result, the thickness of the dielectric film 30 is reduced and extends in the diameter expansion direction. At this time, the electrodes 31a and 31b are also integrated with the dielectric film 30 and extend in the diameter increasing direction. A marker 50 is previously attached to the electrode 31a. The displacement of the marker 50 was measured by the displacement meter 5 and used as the displacement amount of the actuator 3.

(2) Experimental results Next, experimental results will be described. In FIG. 12, the displacement rate with respect to the applied voltage in each actuator of an Example and a comparative example is shown. The displacement rate was calculated by the following formula (2). The vertical axis in FIG. 12 indicates the displacement rate as a multiple of the reference value a.
Displacement rate (%) = (displacement amount / radius of electrode) × 100 (2)
As shown in the graph of FIG. 12, the actuator using the H-NBR film is in the order of Comparative Example 1 → Example 1 → Example 2 → Example 3, and the actuator using the NBR film is Example 5 → In the order of Example 6 → Example 7, the voltage that can be applied increased. That is, the dielectric breakdown strength was increased. In other words, in both the H-NBR film and the NBR film, when the blending amount of the crosslinking agent is increased and the crosslinking density is increased, the dielectric breakdown strength is increased. As a result, the amount of displacement also tends to increase. In particular, in the actuators of Examples 2 and 3 using the H-NBR film by peroxide crosslinking, the dielectric breakdown strength was high and a large displacement was obtained. In addition, compared with the actuator of Example 3, the voltage which can be applied in the actuator of Example 4 became small because the Young's modulus of the H-NBR film was large and it became too hard.

  For each actuator of the example and comparative example, the force generated by multiplying the displacement rate by the Young's modulus was estimated. The results are shown in FIG. The vertical axis in FIG. 13 indicates the force as a multiple of the reference value b.

  As shown in FIG. 13, the actuator using the H-NBR film is in the order of Comparative Example 1 → Example 1 → Example 2 → Example 3, and the actuator using the NBR film is Example 5 → implemented. In the order of Example 6 to Example 7, the dielectric breakdown strength increased and the output force tended to increase.

  The dielectric film of the present invention is useful, for example, for actuators used in artificial muscles for industrial, medical, and welfare robots, small pumps for electronic component cooling and medical use, medical instruments, and the like. The actuator using the dielectric film of the present invention can be used as a substitute for all actuators such as a mechanical actuator such as a motor and a piezoelectric element actuator.

It is a cross-sectional schematic diagram of the actuator of the first embodiment, where (a) shows an off state and (b) shows an on state. It is a perspective view of an actuator of a second embodiment. It is a disassembled perspective view of the actuator. It is an axial sectional view of the actuator. It is a perspective view of the pump of 3rd embodiment. It is a decomposition axial direction sectional view of the pump. It is a disassembled perspective view of the diaphragm member of the pump. It is an axial sectional view in the OFF state of the pump. It is an axial sectional view in the ON state of the pump. It is a top view of the actuator used for the evaluation experiment. It is XI-XI sectional drawing in FIG. It is a graph which shows the displacement rate with respect to the applied voltage in each actuator of an Example and a comparative example. It is a graph which shows the force with respect to the applied voltage in each actuator of an Example and a comparative example.

Explanation of symbols

1: Actuator 2: Actuator element 20: Dielectric film 21a, 21b: Electrode 22: Power supply 24: Stretch member 240: Dielectric film 241a, 241b: Electrode 32: Weight 33: Upper end member 34: Lower end member 90: Wire material 3: Actuator 30 : Dielectric films 31a, 31b: Electrodes 310a, 310b: Terminals 4: Power supply 5: Displacement meter 50: Marker 6: Pump 60: Actuating housing member 600: Actuating opening 601: Actuating fluid chamber 602: Suction cylinder 602a: Suction port 603: Discharge tube 603a: Discharge port 604: Flange 604a: Bolt through hole 607: Clamp member 61: Drive housing member 610: Drive opening 614: Flange 614a: Bolt through hole 615: Bolt 616: Nut 617: Clamp member 62: Diaphragm member 62 : Positive electrode 621: Negative electrode 622: dielectric layer 63: the biasing member 630: hemispherical portion C: heat source cooling circuit S: switch V1: suction side check valve V2: the discharge side check valve

Claims (7)

It is interposed between a plurality of electrodes, expands and contracts according to the electrostatic attraction accompanying a change in voltage applied between the plurality of electrodes, and has a crosslinking density of 5.49 × 10 ⁻⁶ mol / cm ³ or more , A dielectric film for an actuator comprising a nitrile rubber film having a dielectric breakdown strength of 40 V / μm or more in a stretched state with a stretch ratio of 100% calculated by the following formula .
Stretch rate (%) = {√ (S / S ₀ ) −1} × 100
[S ₀ : membrane area before stretching (natural state), S: membrane area after stretching] 2. The dielectric film for an actuator according to claim 1, wherein the nitrile rubber film is crosslinked with one or more crosslinking agents selected from sulfur and organic peroxides. The crosslinking agent is sulfur;
The amount of the crosslinking agent, the nitrile rubber film actuator dielectric film according to claim 2 is 2.2 parts by weight or more 0.44 parts by weight to pre-crosslinking rubber component 100 parts by weight of. The crosslinking agent is at least one selected from organic peroxides,
The amount of the crosslinking agent, the nitrile rubber film actuator dielectric film according to claim 2 2.4 is 9.6 parts by weight or more parts by weight per 100 parts by weight before the rubber component crosslinking. The dielectric film for an actuator according to any one of claims 1 to 4, wherein the nitrile rubber film is at least one selected from acrylonitrile-butadiene copolymer rubber (NBR) and hydrogenated nitrile rubber (H-NBR). . A dielectric film, and a plurality of electrodes disposed via the dielectric film,
Dielectric film is adapted to stretch in response to the electrostatic attractive force due to the change of the voltage applied between the plurality of the electrodes, with the crosslinking density is 5.49 × 10 -6 ^{mol /} cm ³ or more, calculated from the following equation An actuator comprising a nitrile rubber film having a dielectric breakdown strength of 40 V / μm or more in a stretched state with a stretch rate of 100% .
Stretch rate (%) = {√ (S / S ₀ ) −1} × 100
[S ₀ : membrane area before stretching (natural state), S: membrane area after stretching]   The actuator according to claim 6 constituting a pump or an artificial muscle.

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