JP2023090524A - Fluid pressure actuator - Google Patents

Abstract

To provide a fluid pressure actuator capable of preventing twisting at the time of curving (curling).SOLUTION: A fluid pressure actuator 10 is equipped with a cylindrical tube 110 that expands and contracts according to pressure of a fluid, a sleeve 120 that is an elastic structure woven with fiber cords oriented in a predetermined direction, and covers an outer peripheral surface of the tube 110, a sealing member 210 that seals an end portion in an axial direction of the tube 110, and a restraining member 150 that is provided from one end side to the other end side in the axial direction of the tube 110 inside the sleeve 120. The restraining member 150 resists compression in the axial direction, can deform in an orthogonal direction orthogonal to the axial direction, and includes a linear first restraining member, and a linear second restraining member intersecting the first restraining member in the axial direction.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to fluid pressure actuators, and in particular to so-called McKibben-type fluid pressure actuators.

Conventionally, as a fluid pressure actuator that expands and contracts a tube using gas or liquid, a structure (so-called McKibben type) having a rubber tube that expands and contracts by air pressure and a sleeve that covers the outer peripheral surface of the tube has been widely used. It is

Such a McKibben-type fluid pressure actuator is also known to have a structure that bends (curls) when contracted (see Patent Document 1). Specifically, the fluid pressure actuator is provided with a restraining member (leaf spring) provided inside the sleeve from one end side to the other end side in the axial direction of the tube. The restraining member resists compression along the axial direction of the tube and is deformable in orthogonal directions perpendicular to the axial direction.

Japanese Patent Application Laid-Open No. 2021-088999

However, repeated use of the bendable fluid pressure actuator as described above may twist the bending direction due to the habituation of the restraining member (leaf spring). Specifically, when the fluid pressure actuator is bent, the tube may deviate from a straight line along the axial direction and bend while being twisted.

Therefore, the following disclosure has been made in view of such a situation, and aims at providing a fluid pressure actuator that can prevent twisting during bending (curling).

One aspect of the present disclosure is a cylindrical tube (tube 110) that expands and contracts due to the pressure of a fluid, and a stretchable structure in which fiber cords oriented in a predetermined direction are woven, and the outer peripheral surface of the tube A fluid pressure actuator (fluid pressure actuator 10) comprising a sleeve (sleeve 120) that covers the tube and a sealing member that seals the end of the tube in the axial direction, wherein inside the sleeve, in the axial direction A restraining member (restraining member 150) provided from one end side to the other end side is provided, and the restraining member resists compression along the axial direction and is deformable in a direction perpendicular to the axial direction. and includes a linear first restraining member (first restraining member 151) and a linear second restraining member (second restraining member 152) intersecting the first restraining member in the axial direction.

According to the fluid pressure actuator described above, twisting during bending (curling) can be prevented.

FIG. 1 is a side view of the hydraulic actuator 10. FIG. FIG. 2 is a partially exploded perspective view of the fluid pressure actuator 10. FIG. FIG. 3 is a cross-sectional view of the actuator main body 100 along the radial direction _DR . 4A and 4B are explanatory diagrams of the behavior of the fluid pressure actuator 10. FIG.

Hereinafter, embodiments will be described based on the drawings. The same or similar reference numerals are given to the same functions and configurations, and the description thereof will be omitted as appropriate.

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

Actuator main body 100 is composed of tube 110 and sleeve 120 . A fluid flows into the actuator body 100 through the connection port 211a.

As a basic characteristic, the actuator main body 100 contracts in the axial direction D _AX and expands in the radial direction _DR due to the inflow of fluid into the tube 110 . Further, the actuator main body 100 expands in the axial direction D _AX of the actuator main body 100 and contracts in the radial direction _DR due to the outflow of fluid from the tube 110 . Due to such a change in shape of the actuator main body 100, the fluid pressure actuator 10 functions as an actuator.

Such a fluid pressure actuator 10 is a so-called McKibben type, and can be applied not only to artificial muscles, but also to robot limbs (upper limbs, lower limbs, etc.) that require higher ability (contraction force), robot hands, etc. It can also be suitably used for The connecting part 20 is connected with a member or the like that constitutes the limb.

In this embodiment, while using a McKibben-type fluid pressure actuator having such basic characteristics, a restraining member 150 (which may also be referred to as regulating or limiting, hereinafter the same) that restrains compression in the axial direction D _AX is used (Fig. 1 (not shown, see FIGS. 2 and 3, etc.), it is possible to bend (curl) in the orthogonal direction perpendicular to the axial direction _DAX , that is, in the radial direction _DR .

The fluid used to drive the fluid pressure actuator 10 may be either a gas such as air or a liquid such as water or mineral oil. It has high durability that can withstand even

The sealing mechanism 200 and the sealing mechanism 300 seal both ends of the actuator main body 100 in the axial direction _DAX . Specifically, sealing mechanism 200 includes sealing member 210 and crimping member 230 . The sealing member 210 seals the end of the actuator body 100 in the axial direction _DAX . Also, the crimping member 230 crimps the actuator main body 100 together with the sealing member 210 . An indentation 231 is formed on the outer peripheral surface of the caulking member 230 as a mark resulting from caulking of the caulking member 230 by a jig.

The difference between the sealing mechanism 200 and the sealing mechanism 300 is whether or not the connection port 211a is provided.

The connection port 211a is attached with a hose (pipeline) connected to a drive pressure source for the fluid pressure actuator 10, specifically, a gas or liquid compressor. The fluid that has flowed in through the connection port 211a passes through a passage hole (not shown) and flows into the inside of the actuator main body 100, specifically, the inside of the tube 110. As shown in FIG.

FIG. 2 is a partially exploded perspective view of the fluid pressure actuator 10. FIG. As shown in FIG. 2, the fluid pressure actuator 10 includes an actuator main body 100 and a sealing mechanism 200. As shown in FIG.

The actuator main body 100 is composed of the tube 110 and the sleeve 120 as described above.

The tube 110 is a cylindrical tubular body that expands and contracts due to fluid pressure. The tube 110 is made of an elastic material such as butyl rubber because it repeatedly contracts and expands due to the fluid. Further, when the fluid pressure actuator 10 is hydraulically driven, it should be at least one selected from the group consisting of NBR (nitrile rubber) with high oil resistance, hydrogenated NBR, chloroprene rubber, and epichlorohydrin rubber. is preferred.

Sleeve 120 is cylindrical and covers the outer peripheral surface of tube 110 . The sleeve 120 is an elastic structure in which fiber cords oriented in a predetermined direction are woven, and the oriented cords intersect to repeat a rhombic shape. Having such a shape, the sleeve 120 is pantograph-deformed and follows the contraction and expansion of the tube 110 while regulating it.

As the cord constituting the sleeve 120, it is preferable to use a fiber cord of aromatic polyamide (aramid fiber) or polyethylene terephthalate (PET). However, the cord is not limited to this type of fiber cord, and may be, for example, a cord of high-strength fiber such as PBO fiber (polyparaphenylenebenzobisoxazole).

Also, in this embodiment, a restraining member 150 is provided between the tube 110 and the sleeve 120 .

The restraining member 150 is not compressible in the axial direction D _AX and is deformable only along the radial direction D _R (which may also be referred to as the deflection direction). That is, the restraining member 150 resists compression along the axial direction D _AX and is deformable in the orthogonal direction (radial direction D _R ) perpendicular to the axial direction D _AX .

In other words, the restraining member 150 has a characteristic of being difficult to deform along the axial direction _DAX and bending along the radial direction _DR . It should be noted that "deformable" may also mean "curvable" or "curlable".

The restraining member 150 also has a function of restraining (restricting) the expansion of the tube 110 (and the sleeve 120) outward in the radial direction _DR at the position on the outer circumference of the tube 110 where the restraining member 150 is provided. ing.

In the present embodiment, the restraining member 150 is provided inside the sleeve 120, specifically, in a space radially inside the sleeve 120, extending from one end side to the other end side in the axial direction _DAX .

The restraint member 150 is composed of a first restraint member 151 and a second restraint member 152 . The first restraining member 151 and the second restraining member 152 are both linear members and are provided so as to intersect in the axial direction _DAX .

The first constraining member 151 and the second constraining member 152 may be formed from metal monofilaments. Specifically, the first restraining member 151 and the second restraining member 152 are made of piano wire with a diameter of about 0.2 mm. Piano wire may be understood as a steel wire made of carbon steel with a very high carbon content.

The first restraint member 151 formed of piano wire is generally straight when the fluid pressure actuator 10 is not contracted. The second restraint member 152 is also substantially linear when the fluid pressure actuator 10 is not contracted, and is provided so as to intersect the first restraint member 151 at the center of the tube 110 (actuator body 100) in the axial direction _DAX . be done.

Note that the position where the first restraining member 151 and the second restraining member 152 intersect does not have to be strictly at the center of the tube 110 (actuator main body 100) in the axial direction _DAX , but the crossing is generally at the center. It is desirable from the viewpoint of preventing twisting when the fluid pressure actuator 10 contracts.

In addition, since the intersection of the first restraining member 151 and the second restraining member 152 changes due to the contraction of the fluid pressure actuator 10, it is preferable that the intersection be movable in the axial direction _DAX without being fixed. .

The sealing mechanism 200 seals the end of the actuator body 100 in the axial direction _DAX . The sealing mechanism 200 is composed of a sealing member 210 , a locking ring 220 and a crimping member 230 .

The sealing member 210 is inserted through the tubular actuator main body 100 . Specifically, the sealing member 210 has a head portion 211 and a body portion 212 , and the body portion 212 is inserted through the tube 110 .

As the sealing member 210, a metal such as stainless steel can be suitably used, but the material is not limited to such a metal, and a hard plastic material or the like may be used.

Locking ring 220 locks sleeve 120 to sealing member 210 . Specifically, the sleeve 120 is folded outward in the radial direction D _R via the locking ring 220 (not shown in FIG. 2, see FIG. 3).

The locking ring 220 is formed with a notch 221 that is partly cut so that it can be engaged with the sealing member 210 . As the locking ring 220, the same material as the sealing member 210, such as metal or hard plastic material, natural fiber (thread of natural fiber), rubber (for example, O-ring), or the like can be used.

The crimping member 230 crimps the actuator body 100 together with the sealing member 210 . Specifically, the crimping member 230 is provided on the outer peripheral surface of the portion of the actuator main body 100 through which the sealing member 210 is inserted, and crimps the actuator main body 100 and the restraining member 150 onto the sealing member 210 .

As the caulking member 230, metal such as aluminum alloy, brass, and iron can be used. When the crimping member 230 is crimped by a crimping jig, the crimping member 230 is formed with an indentation 231 as shown in FIG.

Although the illustration of the shape of the sealing mechanism 200 (and the sealing mechanism 300) after crimping is omitted, it may be interpreted that the shape is substantially the same as the shape described in JP-A-2021-088999.

(2) Configuration of Actuator Main Body 100 FIG. 3 is a cross-sectional view of the actuator main body 100 along the radial direction _DR . Specifically, FIG. 3 is a cross-sectional view of the actuator main body 100 along the F3-F3 direction in FIG.

As shown in FIG. 3, restraining member 150 is provided between tube 110 and sleeve 120 . Constraining member 150, specifically, first constraining member 151 and second constraining member 152, may be in tight contact with tube 110 and sleeve 120, or may be provided to slightly engage tube 110 as shown in FIG. may

Alternatively, some gaps may be formed between the restraining member 150 and the tube 110 and/or the sleeve 120 and on the side of the restraining member 150 .

(3) Behavior of Fluid Pressure Actuator 10 FIGS. 4A and 4B are explanatory diagrams of the behavior of the fluid pressure actuator 10. FIG. Specifically, FIGS. 4A and 4B show the shapes of the tube 110 and the restraining member 150 that constitute the actuator main body 100 when they are not contracted and when they are contracted, respectively.

As described above, when the fluid flows into the fluid pressure actuator 10, it tries to contract in the axial direction D _AX , but since the cross-shaped restraining member 150 is provided, the force along the axial direction D _AX contraction is constrained (regulated).

In other words, the restraining member 150 made of a hard material such as piano wire serves as a spine, and is located on the opposite side of the tube 110 and the sleeve 120 on the outer periphery where the restraining member 150 is provided (Fig. 4). ), the dimension of the fluid pressure actuator 10 in the axial direction D _AX is shortened by expanding outward in the radial direction D _R , and the fluid pressure actuator 10 (specifically, the actuator main body 100) bends. (Refer to the arrow in FIG. 4(b)).

The restraint member 150 is provided between the rubber tube 110 and the sleeve 120, resists compression in the axial direction _DAX , and is deformable along the orthogonal direction (radial direction _DR ) perpendicular to the and arranged in a part of the actuator main body 100 in the circumferential direction.

That is, when the actuator main body 100 (McKibben) tries to contract along the axial direction D _AX due to the inflow (pressurization) of the fluid into the actuator main body 100, the restraining member 150 has a high compressive rigidity, so that the restraining force is reduced. The portion where the member 150 is arranged cannot contract. On the other hand, other portions of the actuator main body 100 try to contract, so that a force in the bending direction along the orthogonal direction (radial direction D _R ) is generated and bends with the restraint member 150 as the back surface.

Furthermore, since the restraint member 150 is provided in a cross shape so as to intersect at the center of the actuator body 100 in the axial direction D _AX , the actuator body 100 is twisted in the radial direction D _R when the actuator body 100 is contracted. can be effectively suppressed.

(4) Functions and Effects As described above, according to the fluid pressure actuator 10, the restraining member 150 includes the first restraining member 151 and the second restraining member 152 that intersect at the center of the actuator main body 100 in the axial direction _DAX . and

Therefore, even if the fluid pressure actuator 10 contracts and bends, the first restraining member 151 and the second restraining member 152 restrict twisting in the radial direction _DR to each other, so that the tube 110 (actuator main body 100) can be prevented from deviating from a straight line along the axial direction D _AX and bending while being twisted in the radial direction D _R . That is, according to the fluid pressure actuator 10, twisting during bending (curling) can be prevented.

In this embodiment, the first constraining member 151 and the second constraining member 152 may be formed from metal monofilaments. As a result, it is possible to provide the fluid pressure actuator 10 that is lightweight and highly effective in preventing twisting.

Also, the first restraining member 151 and the second restraining member 152 may be provided between the tube 110 and the sleeve 120 . Therefore, the expansion of the tube 110 along the axial direction _DAX can be effectively restrained (restricted). As a result, a force in the bending direction can be efficiently generated, and a greater force in the bending direction can be exerted.

(5) Other Embodiments Although the embodiments have been described above, it is obvious to those skilled in the art that the present invention is not limited to the description of the embodiments, and that various modifications and improvements are possible.

For example, in the above-described embodiment, the first binding member 151 and the second binding member 152 are made of metal monofilaments, but the first binding member 151 and the second binding member 152 may be plate-shaped members. . Also, a plurality of the first restraining member 151 and the second restraining member 152 may be provided. In this case, the numbers of the first restraining members 151 and the second restraining members 152 are preferably the same.

For example, it may be formed by a leaf spring having a width of about 5 mm and a thickness of about 0.5 mm. In this case, the material of the leaf spring is also not particularly limited, but typically, any material such as metal such as stainless steel that is easy to bend and has high resistance to compression may be used. For example, the restraint member may be formed of a carbon fiber reinforced plastic (CFRP) sheet or the like.

Further, in the above-described embodiment, the restraint member 150 is provided from one end side to the other end side in the axial direction _DAX of the actuator body portion 100 (that is, the tube 110 and the sleeve 120). It does not necessarily have to be provided from one end to the other end in the axial direction _DAX of the actuator main body 100 as long as it is provided over substantially the entire region in the axial direction _DAX of 100 .

Furthermore, in the above-described embodiment, the restraint member 150 is used to ensure the flexibility of the fluid pressure actuator, but the flexibility of the fluid pressure actuator may be ensured by another structure. For example, by providing a flexible frame partly bellows-shaped around the fluid pressure actuator, when the fluid pressure actuator contracts, the fluid pressure actuator may be bent with the bellows portion inside. .

Although the present disclosure has been described in detail above, it should be apparent to those skilled in the art that the present disclosure is not limited to the embodiments described in this disclosure. The present disclosure can be practiced with modifications and variations without departing from the spirit and scope of the present disclosure as defined by the claims. Accordingly, the description of the present disclosure is for illustrative purposes and is not meant to be limiting in any way.

10 hydraulic actuator
20 Connector
100 Actuator body
110 tube
120 sleeve
150 Restraining member
151 first restraint member
152 second restraint member
200 sealing mechanism
210 sealing material
211a connection port
211 head
212 Torso
220 locking ring
221 Notch
230 Crimping member
231 Indentation
300 sealing mechanism

Claims (5)

a cylindrical tube that expands and contracts with fluid pressure;
a sleeve, which is a stretchable structure in which fiber cords oriented in a predetermined direction are woven and covers the outer peripheral surface of the tube;
A fluid pressure actuator comprising a sealing member that seals an axial end of the tube,
a restraining member provided inside the sleeve from one end side to the other end side in the axial direction;
The restraining member is
resistant to compression along the axial direction and deformable in orthogonal directions perpendicular to the axial direction;
a linear first restraint member;
A fluid pressure actuator including a linear second restraint member intersecting with the first restraint member in the axial direction. 2. The fluid pressure actuator according to claim 1, wherein said first restraint member and said second restraint member are formed of metal monofilaments. 2. The fluid pressure actuator according to claim 1, wherein said first restraint member and said second restraint member are plate-shaped. The fluid pressure actuator according to any one of claims 1 to 3, wherein the restraint member is provided between the tube and the sleeve. The fluid pressure actuator according to any one of claims 1 to 4, wherein the first restraint member intersects the second restraint member at a central portion in the axial direction.

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