JP2021076167A - Fluid pressure type actuator and artificial muscle - Google Patents

Abstract

To provide a fluid pressure type actuator and an artificial muscle which are excellent in durability and can realize large drive force even with a low pressure.SOLUTION: A fluid pressure type actuator 10 includes a tube 110 which is constituted by multiple layers and in which an innermost layer is softer than an outermost layer, and a sleeve 120 which is a cylindrical structure with cords oriented in a predetermined direction and being woven and which covers an outer peripheral surface of the tube 110.SELECTED DRAWING: Figure 1

Description

The present invention relates to hydraulic actuators and artificial muscles.

Conventionally, as an actuator for expanding and contracting a tube, a pneumatic type having a rubber tube (tubular body) that expands and contracts using air as a fluid and a sleeve (mesh reinforcement structure) that covers the outer peripheral surface of the tube. Actuators (so-called Macchiben type) are widely used.
Further, as an actuator having improved tube durability, an actuator including a tube having a laminated structure of two or more layers composed of a polar rubber layer and a non-polar rubber layer having different SP values is disclosed (for example, Patent Document). 1).

International Publication No. 2018/084123

In order for the actuator to exert a large force, it is necessary to increase the diameter of the tube. On the other hand, when the diameter of the tube is increased, it is necessary to use a large amount of fluid for driving the actuator in the conventional actuator as shown in Patent Document 1, so that it is necessary to increase the size of the device such as the compressor and the battery. It was.
In recent years, the use of assist suits and the like has become popular as a contribution to an active and healthy lifestyle (AHL). In such a situation, there is a demand for miniaturization of devices such as compressors and batteries while maintaining a large driving force.

An object of the present invention is to provide a fluid pressure type actuator and an artificial muscle which are excellent in durability and can realize a large driving force even when the internal pressure is low, and an object of the present invention is to solve the object.

<1> A tube composed of multiple layers, the innermost layer being softer than the outermost layer,
A fluid pressure actuator which is a tubular structure in which a cord oriented in a predetermined direction is woven and includes a sleeve covering the outer peripheral surface of the tube.

<2> The fluid pressure actuator according to <1>, wherein the layer thickness of the outermost layer is thinner than or the same as the total layer thickness of the layers other than the outermost layer.
<3> The modulus tensile modulus of the innermost layer at 30 ° C. is smaller than the modulus tensile modulus of the outermost layer at 30 ° C. at 30 ° C. <1> or <2>. The fluid pressure actuator described.

<4> The fluid pressure actuator according to any one of <1> to <3>, wherein the modulus tensile elastic modulus when the innermost layer is extended by 300% at 30 ° C. is 2 MPa or less.
<5> The fluid pressure actuator according to any one of <1> to <4>, wherein the innermost layer is made of an incompressible material.
<6> The fluid pressure actuator according to any one of <1> to <5>, wherein the elongation at the time of cutting of the innermost layer is 100% or more.

<7> The fluid pressure actuator according to any one of <1> to <6>, wherein the outermost layer is made of a rubber member.
<8> The fluid pressure type actuator according to any one of <1> to <7>, which is a Macchiben type actuator.

<9> An artificial muscle provided with the fluid pressure actuator according to any one of <1> to <8>.

According to the present invention, it is possible to provide a fluid pressure type actuator and an artificial muscle which are excellent in durability and can realize a large driving force even when the internal pressure is low.

It is a side view of one Embodiment of the actuator 10. It is a partially disassembled perspective view of one embodiment of the actuator 10. FIG. 5 is a partial cross-sectional view of an embodiment of the tube 110.

Hereinafter, the present invention will be illustrated in detail based on the embodiments thereof.
In the following description, the description of "A to B" indicating the numerical range represents the numerical range including the end points A and B, and is "A or more and B or less" (in the case of A <B) or "A". Hereinafter, it represents "B or more" (when B <A).
In addition, parts by mass and% by mass are synonymous with parts by weight and% by weight, respectively.

<Fluid pressure actuator>
The fluid pressure actuator of the present invention is a tubular structure composed of a plurality of layers, in which the innermost layer is softer than the outermost layer and a cord oriented in a predetermined direction is woven, and the outer peripheral surface of the tube is formed. It has a sleeve to cover.
Hereinafter, the fluid pressure type actuator may be simply referred to as an actuator.

As described above, in order to increase the driving force of the actuator, it is necessary to increase the tube diameter. On the other hand, in order to reduce the internal pressure (fluid pressure) required for driving and reduce the amount of fluid, the diameter of the void through which the fluid passes may be reduced. If the layer thickness of the tube is increased in order to reduce the void diameter and increase the tube diameter, it is necessary to increase the internal pressure (fluid pressure) required for driving, and it becomes impossible to drive at the target low internal pressure. Therefore, it is conceivable to soften the material of the tube. For example, when a rubber member is used as the material of the tube, the elastic modulus of the rubber member may be lowered, but in that case, when the tube is expanded, the tube bites into the mesh of the sleeve covering the tube. Friction between the tube and the cord of the sleeve may reduce the abrasion resistance of the tube, damage the surface of the tube, and reduce the durability of the tube.

On the other hand, the tube of the actuator of the present invention is composed of a plurality of layers, and the innermost layer is softer than the outermost layer. That is, the innermost layer in contact with the fluid is configured to have a softness that makes it easy to respond even at a low internal pressure, and the outermost layer in contact with the sleeve is harder than the innermost layer and has excellent scratch resistance. As a result, the actuator of the present invention can realize the antinomy that the driving force is large even at a low internal pressure and the abrasion resistance to the sleeve is excellent. As described above, since a large driving force can be realized with a low internal pressure, the number of driving times can be reduced and the load on the compressor can be suppressed. Further, for the same reason, devices such as compressors and batteries can be miniaturized, and actuators having excellent convenience, portability, and the like can be manufactured.

Hereinafter, the actuator of the present invention will be illustrated in detail based on the embodiment with reference to the drawings. The same functions and configurations are designated by the same or similar reference numerals, and the description thereof will be omitted as appropriate.

(1) Overall Schematic Configuration of Actuator FIG. 1 is a side view of the actuator 10 according to the present embodiment. As shown in FIG. 1, the actuator 10 includes an actuator main body 100, a sealing mechanism 200, and a sealing mechanism 300. Further, connecting portions 20 are provided at both ends of the actuator 10.

The actuator main body 100 is composed of a tube 110 and a sleeve 120. The working fluid flows into the actuator main body 100 through the fitting 400 and the passage hole 410. Here, the actuator of the present invention may be a hydraulic type or a pneumatic type.
In the case of the hydraulic type, a liquid is used as the working fluid, and examples of the liquid include oil and water. When the actuator of the present invention is used as a hydraulic actuator, the hydraulic actuator may be hydraulic or hydraulic. In the case of the hydraulic type, as the hydraulic oil, the hydraulic oil conventionally used in the hydraulic drive system can be used.
In the case of the pneumatic type, compressed air is used as the working fluid.

In the tube 110, since the innermost layer in contact with the fluid is softer than the outermost layer, it easily expands even with a minute input, and a large driving force can be obtained. Therefore, the actuator 10 is preferably a pneumatic type. Pneumatic actuators are used in various fields, but are particularly preferably used as artificial muscles for nursing care equipment, welfare equipment, and the like.

Actuator body portion 100, by the working fluid into the tube 110 flows, contracts in the axial direction _{D AX} of the actuator body portion 100 expands radially _{D R.} Further, the actuator body portion 100, by which the working fluid flows out of the tube 110, and expands in the axial direction _{D AX} of the actuator body portion 100, to radially contract _{D R.} Due to such a change in the shape of the actuator main body 100, the actuator 10 functions as an actuator.

Further, such an actuator 10 is a so-called Macchiben type, and can be applied not only for artificial muscles but also for the body limbs (upper limbs, lower limbs, etc.) of a robot that requires higher ability (contraction force). It can be preferably used. Members and the like constituting the body limbs are connected to the connecting portion 20.

Sealing mechanism 200 and the sealing mechanism 300 seals both end portions of the actuator body portion 100 in the axial direction _{D AX.} Specifically, the sealing mechanism 200 includes a sealing member 210 and a caulking member 230. The sealing member 210 seals the end portion in the axial direction _{D AX} of the actuator body portion 100. Further, the caulking member 230 crimps the actuator main body 100 together with the sealing member 210. On the outer peripheral surface of the caulking member 230, indentation 231 which is a trace of the caulking member 230 being crimped by a jig is formed.

The difference between the sealing mechanism 200 and the sealing mechanism 300 is whether or not the fitting 400 (and the passage hole 410) is provided.
The fitting 400 projects so that a hose (pipeline) connected to the driving pressure source of the actuator 10, specifically the compressor of the working fluid, can be attached. The working fluid that has flowed in through the fitting 400 passes through the passage hole 410 and flows into the inside of the actuator main body 100, specifically, the inside of the tube 110.

FIG. 2 is a partially exploded perspective view of the actuator 10. As shown in FIG. 2, the actuator 10 includes an actuator main body 100 and a sealing mechanism 200.
As described above, the actuator main body 100 is composed of the tube 110 and the sleeve 120.

The tube 110 is preferably a cylindrical body from the viewpoint of expanding and contracting due to the fluid pressure and evenly distributing the fluid pressure. Since the tube 110 repeatedly contracts and expands due to the working fluid, it repeatedly contacts the sleeve 120, but the tube 110 is composed of a plurality of layers, and the outermost layer is excellent in scratch resistance.
When the actuator 10 is used as a hydraulic actuator, the innermost layer in contact with the fluidized liquid is made into a water-resistant or oil-resistant layer so that the actuator 10 has durability against the fluidized liquid and at the same time has abrasion resistance against the sleeve 120. it can.

FIG. 3 is a partial cross-sectional view of an embodiment of the tube 110.
Tube 110 shown in FIG. 3, the innermost layer 111 located on the inner surface side of the tube, adjacent the radially D _R outside of the innermost layer 111, two layers of the outermost layer 112. Located on the outer surface side of the tube 110 Has a structure.
The inner layer may be one layer or may be composed of two or more layers. In FIG. 3, the inner layer is composed of one layer, and the tube is composed of the innermost layer 111 and the outermost layer 112. The innermost layer 111 is softer than the outermost layer 112.

Specifically, it is preferable that the modulus tensile elastic modulus of the innermost layer 111 when expanded at 30 ° C. is smaller than the modulus tensile modulus of elasticity of the outermost layer 112 when expanded at 30 ° C.
The modulus tensile elastic modulus (M300) of the innermost layer 111 and the outermost layer 112 when stretched by 300% at 30 ° C. can be measured by a method according to JIS K 6251 (2017).
Further, the innermost layer 111 preferably has a modulus tensile elastic modulus (M300) of 2 MPa or less when stretched by 300% at 30 ° C. The lower limit of M300 in the innermost layer is not particularly limited as long as it does not flow, but is usually limited to 0.6 MPa, and M300 in the innermost layer is more preferably 0.8 to 3.0 MPa, and 1.0 to 2. 0 Mpa is more preferable.

From the viewpoint of durability (particularly, abrasion resistance to the sleeve), the outermost layer 112 preferably has a modulus tensile elastic modulus (M300) of more than 2 MPa when stretched by 300% at 30 ° C. The upper limit of the outermost layer M300 is not particularly limited as long as it can follow the expansion of the tube 110, but is usually about 3.0 MPa. The outermost layer M300 is more preferably 2.0 to 5.0 MPa, further preferably 2.5 to 4.0 Mpa.

Regarding the softness of the innermost layer 111, from another point of view, the hardness (shore A) of the innermost layer 111 is preferably 33 to 43, and more preferably 35 to 40.
The hardness (shore A) of the outermost layer 112 is preferably 40 to 50, more preferably 43 to 48.
The hardness (shore A) of the innermost layer 111 and the outermost layer 112 can be measured by a method according to JIS K6253-3 (2012) using a durometer hardness tester.

When the inner layer is composed of two or more layers, the innermost layer 111 in contact with the fluid may be softer than the outermost layer 112, and the elastic modulus of the inner layers other than the innermost layer 111 is not limited. For example, the elastic modulus of the inner layers other than the innermost layer 111 may be as high as the outermost layer 112 or as low as the innermost layer 111. However, since the durability of the tube is protected by the presence of the outermost layer 112, the elastic modulus of the inner layers other than the innermost layer 111 is the same as that of the innermost layer 111 from the viewpoint of improving the responsiveness at a minute input and improving the driving force. It is preferably as low as possible.

When the inner layer is composed of two or more layers, that is, when one or more intermediate layers are provided between the innermost layer 111 and the outermost layer 112 in FIG. 3, the intermediate layer is, for example, the innermost layer 111 and the outermost layer 112. It is conceivable to use a functional layer or the like containing various functional components such as an adhesive layer for improving the adhesiveness with the material. As the adhesive layer, an appropriate adhesive may be used depending on the properties of the innermost layer 111 and the outermost layer 112. For example, "Metallock R-17" manufactured by Toyo Kagaku Kenkyusho Co., Ltd. can be preferably used.

Further, the layer thickness of the outermost layer 112 is preferably thinner than or the same as the total thickness of the layers other than the outermost layer 112. The outermost layer 112 needs to be able to withstand friction with the sleeve 120, but it is preferable that the outermost layer 112 is thin for smooth driving. Further, the layer (inner layer) other than the outermost layer 112 is preferably thick in order to reduce the volume of the fluid.

Further, in the present invention, the layer thickness of the tube 110 is preferably 0.2 to 10.0 mm from the viewpoint of the durability of the actuator and the operating length. When the layer thickness of the tube 110 is 0.2 mm or more, the durability of the tube 110 is excellent, and when the layer thickness of the tube 110 is 10.0 mm or less, the expandability of the tube 110 is excellent, and the input for a minute input is excellent. Excellent responsiveness. Further, the diameter (outer diameter) of the tube 110 can be appropriately selected according to the intended use.
The layer thickness of the tube 110 means the total thickness of the tube 110 (the total layer thickness of all the layers). For example, the tube 110 is if a two-layer structure consisting of an innermost layer 111 and the outermost layer 112. shown in FIG. 3, the thickness of the innermost layer 111 in the radial direction of the outermost layer 112 _{(D R} direction) of the tube 110 The layer thickness.
The layer thickness of the tube 110 is more preferably 0.3 to 9.0 mm from the viewpoint of further improving the input response and wear resistance of the actuator.

The innermost layer 111 is preferably made of an incompressible material. The incompressible material refers to a material whose volume does not change even when it receives an external load, and examples thereof include a rubber member, a thermoplastic elastomer member, and a thermosetting elastomer member. When the internal pressure is applied to the actuator 10, if the innermost layer 111 is compressed by the internal pressure, the actuator 10 cannot generate a large driving force.
The incompressible material is preferably a rubber member from the viewpoint of responding quickly even with a minute input and having durability that can withstand repeated expansion and contraction of the tube.

As the rubber member, vulcanized rubber having a rubber composition containing at least one rubber component of synthetic diene rubber and natural rubber, a filler, a vulcanizing agent, a vulcanization accelerator, and the like can be used.
Examples of the synthetic diene rubber include butadiene rubber (BR), isoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), and the like, and butadiene rubber is preferable.
The rubber component preferably contains a synthetic diene rubber and a natural rubber, and preferably contains a butadiene rubber (BR) and a natural rubber (NR).
When the actuator 10 is of the hydraulic type, it is preferable to use a rubber member having resistance to the liquid to be used for the innermost layer 111. Specifically, the rubber composition constituting the innermost layer 111 is a rubber component such as acrylonitrile-butadiene rubber (NBR), hydride acrylonitrile-butadiene rubber (hydride NBR), chloroprene rubber (CR), and epichlorohydrin rubber. Is preferably included.

The material of the outermost layer 112 is not particularly limited, but it is preferable to use a rubber member for the outermost layer 112 from the viewpoint of having scratch resistance to the sleeve 120 and easily following the expansion and contraction of the innermost layer 111.
In order to change the modulus tensile elastic modulus between the innermost layer 111 and the outermost layer 112, the type of rubber component contained in the rubber composition may be changed, or the amounts of the filler, vulcanizing agent, vulcanization accelerator, etc. may be changed. .. For example, the modulus tensile elastic modulus of the rubber member can be increased by increasing the amount of any one or more of the filler, the vulcanizing agent, and the vulcanization accelerator.

The elongation at the time of cutting of the innermost layer 111 is preferably 100% or more from the viewpoint of improving the durability against deformation due to repeated expansion and contraction. The elongation at the time of cutting of the innermost layer 111 is preferably 200% or more, more preferably 300% or more, and further preferably 500% or more.
The elongation at the time of cutting can be measured by a method according to JIS K 6251 (2017).

The sleeve 120 has a cylindrical shape and covers the outer peripheral surface of the tube 110. The sleeve 120 is a structure in which cords oriented in a predetermined direction are woven, and the shape of a rhombus is repeated by intersecting the oriented cords. By having such a shape, the sleeve 120 deforms in a pantograph and follows the contraction and expansion of the tube 110 while regulating the contraction and expansion.

The cords constituting the sleeve 120 include polyamide fibers such as aramid fibers (aromatic polyamide fibers), polyhexamethylene adipamide (nylon 6,6) fibers, polycaprolactam (nylon 6) fibers, and polyethylene terephthalate (PET) fibers. , Polyester fiber such as polyethylene naphthalate (PEN) fiber, polyurethane fiber, rayon, acrylic fiber, and a fiber cord made of at least one fiber material selected from polyolefin fiber is preferably used. Among these, it is particularly preferable to use a cord made of aramid fiber from the viewpoint of the strength of the sleeve 120.
However, the fiber cord is not limited to this type, and for example, a high-strength fiber such as PBO (polyparaphenylene benzobisoxazole) fiber or a metal cord composed of ultrafine filaments is used. May be good.

Further, the surface of the above-mentioned fiber cord and metal cord may be coated with a mixture of a thermosetting resin and latex, rubber or the like. When the surface of the cord is coated with these materials, the coefficient of friction of the surface of the cord can be appropriately reduced while improving the durability of the cord.
The solid content in the mixture of the thermosetting resin and the latex is preferably 15% by mass or more and 50% by mass or less, and more preferably 20% by mass or more and 40% by mass or less. Examples of the thermosetting resin include phenol resin, resorcin resin, urethane resin and the like, and examples of the latex include vinylpyridine (VP) latex, styrene-butadiene rubber (SBR) latex, and acrylonitrile-butadiene rubber (NBR) latex. And so on.

The sleeve may have a single-layer structure or a multi-layer structure. In the latter case, even if the sleeves are laminated so that the cross sections are concentric, they are wound so that the cross section is spiral. It may have a structure.

2, the sealing mechanism 200 seals the end portion in the axial direction _{D AX} of the actuator body portion 100. The sealing mechanism 200 is composed of a sealing member 210, a locking ring 220, and a caulking member 230.

The sealing member 210 has a body portion 211 and a collar portion 212. As the sealing member 210, a metal such as stainless steel can be preferably used, but the sealing member 210 is not limited to such a metal, and a hard plastic material or the like may be used.

The body portion 211 has a circular tubular shape, and the body portion 211 is formed with a passage hole 215 through which a working fluid passes. The passage hole 215 communicates with the passage hole 410 (see FIG. 1). A tube 110 is inserted through the body portion 211.

The flange portion 212 is continuous with the body portion 211, located on the end side in the axial direction _{D AX} of the actuator 10 than the body portion 211. The flange portion 212 has a larger outer diameter in the radial direction _{D R} than the body portion 211. The collar portion 212 locks the tube 110 and the locking ring 220 inserted through the body portion 211.

Concavo-convex portions 213 are formed on the outer peripheral surface of the body portion 211. The uneven portion 213 contributes to suppressing slippage of the tube 110 inserted through the body portion 211. It is preferable that three or more convex portions are formed by the concave-convex portions 213.

Further, a small diameter portion 214 having an outer diameter smaller than that of the body portion 211 is formed at a position of the body portion 211 closer to the collar portion 212.

The locking ring 220 locks the sleeve 120. The sleeve 120 may be folded back in the radial direction _{D R} outward through the locking ring 220.

The outer diameter of the locking ring 220 is larger than the outer diameter of the body portion 211. The locking ring 220 locks the sleeve 120 at the position of the small diameter portion 214 of the body portion 211. That is, the locking ring 220, a radial direction _{D R} outside of the body 211, in a position adjacent to the flange portion 212, locking the sleeve 120.

In this embodiment, the locking ring 220 is divided into two parts so that the locking ring 220 can be locked to the small diameter portion 214, which is smaller than the body portion 211. The locking ring 220 is not limited to the two divisions, and may be divided into more portions, or some of the divided portions may be rotatably connected.

As the locking ring 220, the same metal or hard plastic material as the sealing member 210 can be used.

The caulking member 230 crimps the actuator main body 100 together with the sealing member 210. As the caulking member 230, metals such as aluminum alloy, brass and iron can be used. When the caulking member 230 is caulked by the caulking jig, the indentation 231 as shown in FIG. 1 is formed on the caulking member 230.

Hereinafter, the present invention will be described in more detail with reference to specific embodiments, but these embodiments are for the purpose of exemplifying the present invention and do not limit the present invention in any way.

<First Embodiment>
(Manufacturing of tubes)
50 parts by mass of carbon black and 0.6 parts by mass of vulcanizing agent and 0.4 parts by mass of carbon black with respect to 100 parts by mass of rubber component of 20 parts by mass of natural rubber and 80 parts by mass of polybutadiene rubber. A vulcanization package containing a parts-by-mass vulcanization accelerator and an additive such as an antiaging agent were mixed to obtain a rubber composition for the outermost layer.
Further, with respect to 100 parts by mass of the rubber component of 20 parts by mass of natural rubber and 80 parts by mass of polybutadiene rubber, 50 parts by mass of carbon black and 0.1 parts by mass of vulcanizing agent and 0 parts by mass of 100 parts by mass of rubber component. A vulcanization package containing 8 parts by mass of a vulcanization accelerator was mixed with an additive such as an antiaging agent to obtain a rubber composition for the innermost layer.

By processing the obtained rubber composition for the outermost layer and the rubber composition for the innermost layer with a two-layer extrusion molding machine, each rubber composition is vulcanized, and two types and two layers having a cylindrical shape with a length of 300 mm are obtained. Tube was prepared.
The outermost layer had a thickness of 1.7 mm, and the innermost layer had a thickness of 1.7 mm.
The modulus tensile elastic modulus of the outermost layer when stretched by 300% at 30 ° C. was 3.5 MPa. The modulus tensile elastic modulus of the vulcanized rubber of the rubber composition for the innermost layer when stretched by 300% at 30 ° C. was 1.5 MPa, and the elongation at cutting was 600% at 30 ° C. Therefore, in the first embodiment, the tube is composed of a plurality of layers, and the innermost layer is softer than the outermost layer.
The modulus tensile elastic modulus and the elongation at the time of cutting when each layer was extended by 300% were measured by a method according to JIS K 6251 (2017).

(Manufacturing of sleeves)
Two 2200 dtex aramid fibers were used as the raw yarn, and 12 times / 10 cm lower twist was applied, and then 12 times / 10 cm upper twist was applied to prepare an aramid fiber cord having a diameter of 0.7 mm.
A mesh-like inner layer sleeve prepared by knitting 64 aramid fiber cords was prepared. This sleeve was a mesh-like tubular body in which 64 aramid fiber cords were observed on the circumference in the cross section. Specifically, the sleeve is obliquely crossed with 32 aramid fiber cords arranged at equal intervals, parallel and spirally, and the 32 aramid fiber cords, and arranged at equal intervals, parallel and spirally. It was a mesh-like tubular body in which the other 32 aramid fiber cords were woven alternately, and the angle of each cord with respect to the axial direction was 25 degrees.

(Manufacturing of pneumatic actuators)
Using the manufactured tubes and sleeves, pneumatic actuators having the structures shown in FIGS. 1 and 2 were produced. The length between the sealing mechanism 200 and the sealing mechanism 300 is 250 mm.
The obtained pneumatic actuator realized a large driving force even when the applied internal pressure was 0.3 MPa. It should be noted that the large driving force can be confirmed by the difference in the force generated by the same applied internal pressure. Further, it can be seen that the outermost layer of the tube is less likely to bite into the mesh of the sleeve when the tube is expanded, and is excellent in scratch resistance.

<Example for comparison>
The pneumatic actuator of the comparative embodiment was manufactured in the same manner as in the first embodiment except that the tube was manufactured as follows.

In the production of the tube of the first embodiment, the rubber composition for the outermost layer was also used for forming the innermost layer, and a cylindrical type 1 two-layer tube having a length of 300 mm was produced. The outermost layer had a thickness of 1.7 mm, and the innermost layer had a thickness of 1.7 mm.
The modulus tensile elastic modulus of the outermost layer and the innermost layer at 30 ° C. when stretched by 300% was 3.0 MPa. The elongation at break of the innermost layer was 580% at 30 ° C. Therefore, in the comparative embodiment, the tube is composed of a plurality of layers, but the innermost layer is not softer than the outermost layer.
The modulus tensile elastic modulus and the elongation at the time of cutting when each layer was extended by 300% were measured by a method according to JIS K 6251 (2017).

The obtained pneumatic actuator could not realize a large driving force unless the applied internal pressure was increased to 0.5 MPa. The outermost layer of the tube does not easily bite into the mesh of the sleeve when the tube expands, and has excellent scratch resistance.

10: Actuator 20: Connecting part 100: Actuator main body 110: Tube 111: Innermost layer 112: Outermost layer 120: Sleeve 200: Sealing mechanism 210: Sealing member 211: Body part 212: Flange part 213: Concavo-convex part 214: small-diameter portion 215: passage hole 220: locking ring 230: caulking member 231: indentation 300: sealing mechanism 400: fitting 410: passage hole _{D AX:} axial _{D R:} radial

Claims (9)

A tube composed of multiple layers, the innermost layer being softer than the outermost layer,
A fluid pressure actuator which is a tubular structure in which a cord oriented in a predetermined direction is woven and includes a sleeve covering the outer peripheral surface of the tube. The fluid pressure actuator according to claim 1, wherein the outermost layer has a thickness smaller than or the same as the total thickness of the layers other than the outermost layer. The fluid pressure actuator according to claim 1 or 2, wherein the modulus tensile elastic modulus of the innermost layer at 30 ° C. is smaller than the modulus tensile modulus of elasticity of the outermost layer at 30 ° C. .. The fluid pressure actuator according to any one of claims 1 to 3, wherein the modulus tensile elastic modulus when the innermost layer is extended by 300% at 30 ° C. is 2 MPa or less. The fluid pressure actuator according to any one of claims 1 to 4, wherein the innermost layer is made of an incompressible material. The fluid pressure actuator according to any one of claims 1 to 5, wherein the elongation at the time of cutting of the innermost layer is 100% or more. The fluid pressure actuator according to any one of claims 1 to 6, wherein the outermost layer is made of a rubber member. The fluid pressure type actuator according to any one of claims 1 to 7, which is a Macchiben type actuator. An artificial muscle comprising the fluid pressure actuator according to any one of claims 1 to 8.

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