Fluid pressure actuator

Abstract

A fluid pressure actuator includes: a tubular pipe (24) that expands and contracts in accordance with a pressure of a fluid; a sleeve (26) that covers an outer peripheral surface of the pipe (24); a pair of sealing members that seal end portions of the pipe; a long strip-shaped restraining member (28) that is disposed on an outer side in a radial direction of the pipe (24) and on an inner side in the radial direction of the sleeve (26) from one side to the other side in an axial direction (S), is able to resist compression in the axial direction (S), and bends in a cross direction that intersects the axial direction (S); and a fixing member (36) that fixes the sleeve (26) and the restraining member (28) from an outer side of the sleeve (26) to an insertion portion (32B) in a position corresponding to one end portion of the restraining member (28), i.e., a restraining end portion (29), the restraining end portion (29) being fixed to an outer surface of the pipe (24) at a position radially outward of the outer surface corresponding to a portion of the pipe (24) before bending that is not inserted into the insertion portion (32B).

Description

Technical Field

[0001] This invention relates to fluid pressure actuators. Background Technology

[0002] Patent Document 1 discloses a fluid pressure actuator comprising: a cylindrical tube that expands and contracts due to fluid pressure; a sleeve, which is a stretchable structure formed by weaving in fiber cords oriented in a predetermined direction, covering the outer circumferential surface of the tube; and a sealing member that seals the axial end of the tube. The fluid pressure actuator includes a restraining member disposed on the inner side of the sleeve from one axial end to the other, the restraining member being able to resist compression along the axial direction and deform in a direction orthogonal to the axial direction.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2021-088999 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] In such a fluid pressure actuator, the restraining member is fixed to the sealing member along with the pipe and sleeve. When the fluid pressure actuator is operating, the pressure inside the pipe rises, and the shape of the central portion not fixed to the fixed part increases. Therefore, the restraining member bends at the boundary between the fixed part and the central portion. If this bend increases, the load on the restraining member increases.

[0008] The purpose of this invention is to provide a fluid pressure actuator for suppressing the load on a restraining member.

[0009] Solution for solving the problem

[0010] The first technical solution's fluid pressure actuator comprises: a cylindrical tube that expands and contracts according to fluid pressure; a sleeve covering the outer circumferential surface of the tube, restricting the tube from elongating axially due to expansion and allowing the tube to expand radially due to expansion; a pair of sealing members having insertion portions inserted from a top side toward one and the other axial ends of the tube, respectively, the pair of sealing members sealing the tube ends; an elongated restraining member extending radially outward from one side of the axial direction and radially inward from the sleeve, capable of resisting axial compression and bending in a direction intersecting the axial direction; and a fixing member fixing the sleeve and the restraining member from the outside of the sleeve toward the insertion portion at a position corresponding to one end of the restraining member, i.e., the restraining end, the restraining end being fixed to the outer surface of the tube at a position radially outward from the outer surface of the insertion portion corresponding to the portion of the tube not inserted into the insertion portion before bending.

[0011] In the fluid pressure actuator of the first technical solution, the restraining end is fixed to the outer surface of the tube at a position radially outward from the outer surface corresponding to the portion of the tube that was not inserted into the insertion part before bending. Therefore, even if the shape of the central part of the tube increases when the tube expands according to the pressure of the fluid, the degree of deformation of the restraining member can be reduced and the load suppressed.

[0012] In the fluid pressure actuator of the second technical solution, at the maximum internal pressure, the maximum diameter of the tube is within 160% of the diameter of the portion of the insertion part where the constraint end is disposed.

[0013] This configuration allows for the suppression of load on the restraint components while ensuring the deformation of the fluid pressure actuator during operation.

[0014] In the fluid pressure actuator of the third technical solution, the diameter of the insertion part increases as it moves from the top end toward the base end.

[0015] By setting the tip of the insertion part to a small diameter and increasing the diameter as it moves toward the base end, the constraint end of the constraint member can be smoothly deformed and positioned along the outside of the insertion part.

[0016] Invention Effects

[0017] According to the present invention, a fluid pressure actuator that suppresses the load on a restraining member can be provided. Attached Figure Description

[0018] Figure 1 This is a top view of a fluid pressure actuator according to an embodiment of the present disclosure.

[0019] Figure 2This is an exploded perspective view of one end of the axial direction of the fluid pressure actuator according to an embodiment of the present disclosure.

[0020] Figure 3 This is a perspective view illustrating a sealing member connector according to an embodiment of the present disclosure.

[0021] Figure 4 This is a cross-sectional view of the connection portion (when not driven) between the sealing member connector on one end side and the actuator body of an embodiment of this disclosure.

[0022] Figure 5 This is a cross-sectional view of the connection portion (when driven) between the sealing member connector on one end side and the actuator body of an embodiment of this disclosure.

[0023] Figure 6 This is a cross-sectional view of the connection portion (when driven) between the sealing member connector on one end side and the actuator body of an embodiment of this disclosure.

[0024] Figure 7 This is a cross-sectional view illustrating the operation of a fluid pressure actuator according to an embodiment of the present disclosure.

[0025] Figure 8 This is a cross-sectional view of the connection between the sealing member connector on one end and the actuator body (when not in operation), as in the past.

[0026] Figure 9 This is a cross-sectional view of the connection between the sealing member connector on one end and the actuator body (when driven), as in the past. Detailed Implementation

[0027] Hereinafter, embodiments of the technology implementing this disclosure will be described in detail with reference to the accompanying drawings.

[0028] Furthermore, for components and processes that serve the same function, the same reference numerals are used in all the accompanying drawings, and sometimes repeated descriptions are appropriately omitted. Additionally, this disclosure is not limited to any of the following embodiments, and modifications and implementations can be appropriately made within the scope of the purpose of this disclosure.

[0029] like Figure 1 As shown, the fluid pressure actuator 20 of the embodiments of this disclosure includes an actuator body 22, a first sealing member 30A, and a second sealing member 30B.

[0030] Also Figure 2As shown, the actuator body 22 includes a tube 24, a sleeve 26, and a restraining member 28. The tube 24 is cylindrical and capable of expansion and contraction based on elastic deformation, growing and shrinking due to pressure changes in the internal fluid. The axial direction S of the tube 24 is defined as "axial S". The tube 24 can be made of an elastic material such as butyl rubber. Air can be used as the fluid supplied to the tube 24, in which case the fluid pressure actuator 20 becomes a pneumatic actuator. Furthermore, when the fluid pressure actuator 20 is hydraulically driven, it is preferably selected from at least one of the group consisting of NBR (nitrile butadiene rubber), hydrogenated NBR, chloroprene rubber, and chloroprene rubber, which have high oil resistance.

[0031] The sleeve 26 is cylindrical and covers the outer periphery of the tube 24. The sleeve 26 is a stretchable structure obtained by weaving together fiber cords oriented in a predetermined direction, the oriented cords crossing at a predetermined angle θ relative to the axial direction S. By having such a shape, the sleeve 26 can undergo scaling deformation by changing the angle θ, restricting and following the contraction and expansion of the tube 24.

[0032] As the cord constituting the sleeve 26, it is preferable to use fiber cords of aromatic polyamide (aramid fiber) or polyethylene terephthalate (PET). However, it is not limited to such types of fiber cords, and for example, it may also be cords of other high-strength fibers such as PBO fiber (poly(p-phenylenebenzodioxazole)).

[0033] The constraint member 28 is disposed between the pipe 24 and the sleeve 26. The constraint member 28 is a long strip plate, with its length direction arranged along the axial direction S of the pipe 24, covering a part of the outer periphery of the pipe 24, and is disposed from one end of the pipe 24 to the other end.

[0034] The constraint member 28 includes a constraint main body 28A and a constraint end 29. The constraint main body 28A is the portion arranged along the axial direction S of the tube 24 and is not covered by the fixing member 36 described later. The constraint end 29 is formed at one end of the constraint member 28. The constraint end 29 is fixed together with the tube 24 and the sleeve 26 to the insertion portion 32B described later by the fixing member 36 described later.

[0035] The constraint member 28 is made of a material that does not expand or contract under pressure and is capable of flexing and deforming towards each other at the ends. A leaf spring can be used as the constraint member 28. The size of the leaf spring is determined by the size of the hydrodynamic actuator 20, the required bending output, etc. Furthermore, the material of the leaf spring is not particularly limited; typically, a material that is easily flexed and resistant to compression, such as stainless steel, is sufficient. Alternatively, it can be formed from a thin sheet of carbon fiber reinforced plastic (CFRP).

[0036] The first sealing member 30A has a sealing member connector 32, a locking wire 34, and a fixing member 36.

[0037] like Figure 3 and Figure 4 As shown, the sealing member connector 32 has an integrally formed base end portion 32A and an insertion portion 32B. The base end portion 32A is a generally rectangular parallelepiped with a diameter larger than the outer diameter of the tube 24, and the insertion portion 32B extends axially S from one end of the base end portion 32A. The insertion portion 32B has, in sequence from the base end portion 32A side, a small diameter portion 48, a tapered portion 49, a large diameter portion 50, and a bamboo shoot-shaped portion 52.

[0038] A bamboo shoot-shaped portion 52 protrudes from the tip of the insertion portion 32B, and the tube 24 is inserted from the tip of the bamboo shoot-shaped portion 52. The large-diameter portion 50 is continuously formed on the base end portion 32A side of the bamboo shoot-shaped portion 52, and is a circular plate with a diameter larger than that of the bamboo shoot-shaped portion 52. A step 42 is formed between the large-diameter portion 50 and the bamboo shoot-shaped portion 52.

[0039] The tapered portion 49 and the large-diameter portion 50 are continuously formed on the base end portion 32A side of the large-diameter portion 50 (the deep side of the insertion portion 32B), and the tapered shape is such that the diameter decreases as it moves toward the base end portion 32A side.

[0040] A small diameter portion 48 is formed between the tapered portion 49 and the base end portion 32A, and the diameter from the tapered portion 49 to the base end portion 32A is the same. The outer diameter of the small diameter portion 48 is smaller than the diameter of the tip of the bamboo shoot-shaped portion 52. A step 35 is formed between the small diameter portion 48 and the base end portion 32A.

[0041] The base end 32A of the bamboo shoot-shaped portion 52 is formed into three sections (top 52A, middle section 52B, and base 52C) with a large diameter cone shape. In terms of the outer diameter of the bamboo shoot-shaped portion 52, the top end 52A is the smallest, increasing in the order of the middle section 52B and the base 52C. The bamboo shoot-shaped portion 52 as a whole also has a shape that gradually expands in diameter from the top end to the base end along the axial direction S. Furthermore, in terms of the angle relative to the axial direction S, the top end 52A is the largest, and the base end 52C is the smallest. When viewed in a cross-section along the axial direction S, the inclination gradually decreases from the top end 52A towards the base end 52C.

[0042] The largest part of the bamboo shoot-shaped portion 52 (the basal end 32A side of the basal end 52C, hereinafter referred to as the "outermost part of the bamboo shoot 53") is larger than the inner diameter of the tube 24 in the uninserted state.

[0043] As a sealing component connector 32, stainless steel or other metals are preferred, but it is not limited to such metals; rigid plastic materials or the like can also be used.

[0044] like Figure 4As shown, a flow path R is formed in the sealing member connector 32. This flow path R extends axially along the central portion of the insertion portion 32B as viewed from the axial direction S, and communicates with the connection hole H on the side of the base end portion 32A (see also [reference]). Figure 6 An air supply hose (not shown) is connected to connection hole H to supply compressed air to flow path R.

[0045] like Figure 4 As shown, the constraint end 29 of the constraint member 28 is positioned in the axial direction S corresponding to the bamboo shoot-shaped portion 52 of the sealing member connector 32. The constraint body portion 28A and the constraint end 29 of the constraint member 28 are positioned radially outward from the outer surface of the outer surface of the portion of the tube 24 that is not inserted into the central portion 32B. That is, as... Figure 4 As shown, the constraint member 28 is configured such that the constraint body portion 28A and the constraint end portion 29 extend in a straight line, and the constraint body portion 28A is separated from the tube 24 (forming a gap). The top end of the constraint end portion 29 is positioned opposite to the step 42 of the large diameter portion 50.

[0046] The locking wire 34 is a loop formed by winding a wire multiple times, and is wound around the outside of the sleeve 26 such that it is sandwiched between the loop and the small diameter portion 48. Furthermore, the sleeve 26 is folded outwards, clamping the locking wire 34. Thus, the sleeve 26 is locked to the sealing member connector 32. A metal wire can be used as the locking wire 34.

[0047] The fixing member 36 is arranged such that it covers the insertion part 32B on the outer periphery of the actuator body 22. Inside the fixing member 36, corresponding to the bamboo shoot-shaped part 52, the bamboo shoot-shaped part 52, the tube 24, the constraint body part 28A of the constraint member 28, the sleeve 26 (before folding), and the sleeve 26 (after folding) are arranged. Inside the fixing member 36, the small diameter part 48, the constraint end 29 of the constraint member 28, the sleeve 26 (before folding), the locking line 34, and the sleeve 26 (after folding) are arranged.

[0048] By chiseling the fixing member 36 radially inward, the tube 24, the restraining member 28, and the sleeve 26 can be fixed to the sealing member connector 32.

[0049] With the fixing member 36 in place, the constraint end 29 of the constraint member 28 is positioned radially inward due to the compression deformation of the tube 24. The portion of the constraint end 29 corresponding to the outermost 53 of the bamboo shoot is positioned radially outward compared to the outer surface of the portion of the tube 24 corresponding to the constraint body portion 28A.

[0050] The second sealing member 30B has the same structure as the first sealing member 30A. However, no flow path R is formed.

[0051] Next, the assembly steps of the fluid pressure actuator 20 of this embodiment will be described.

[0052] <Assembly of Fluid Pressure Actuator 20>

[0053] In this embodiment, the first sealing member 30A and the actuator body 22 are assembled at one end of the fluid pressure actuator 20 as follows.

[0054] First, insert the tube 24 into the insertion portion 32B of the sealing member connector 32 until one end of the tube 24 abuts against the step 42. Next, configure the restraint member 28 such that the top end of the restraint end 29 is at the same position as the top end of the tube 24.

[0055] Next, the sleeve 26 is fitted over the base end 32A of the tube 24 and the sealing member connector 32 and covers the outer peripheral surface of the restraint member 28. The locking line 34 is wound around the sleeve 26 from the radial outside, thereby installing it at the position of the small diameter portion 48.

[0056] Next, the sleeve 26 is folded inwards towards the insertion portion 32B of the sealing member connector 32 with the locking line 34 facing inwards. The fixing member 36 is then positioned and tightened from the radially outer side of the sleeve 26 across the end of the small-diameter portion 48 of the insertion portion 32B. Thus, on one side of the actuator body 22 along the axial direction S, the tube 24, the restraining member 28, and the sleeve 26 are fixed to the sealing member connector 32.

[0057] Next, on the other side of the axial direction S, the second sealing member 30B and the actuator body 22 are assembled in the same manner as the first sealing member 30A.

[0058] According to the above steps, one side and the other side of the tube 24 are sealed by the first sealing member 30A and the second sealing member 30B, and assembled into a fluid pressure actuator 20.

[0059] Next, the operation of the fluid pressure actuator 20 of this disclosure will be described.

[0060] <Operation of the fluid pressure actuator 20>

[0061] like Figure 6 As shown, the fluid pressure actuator 20 is used with a first sealing member 30A fixed at one end and a second sealing member 30B at the other end as a free end.

[0062] If compressed air flows in through the connection hole H, the pressure inside the fluid actuator 20 increases. Due to the increased internal pressure, the tube 24 expands due to elastic deformation, and the sleeve 26 undergoes scaling deformation at an increasing angle θ, exerting a force in the direction of shortening of the actuator body 22. Since the outer peripheral sidewall of the actuator body 22 where the constraint member 28 is located is restricted from shortening, the outer peripheral wall of the actuator body 22 on the side without the constraint member 28 shortens when viewed from the axial direction S. As a result, the constraint member 28 flexes and deforms, such as... Figure 7 As shown by the double-dotted line, the actuator body 22 is bent as a whole.

[0063] At this time, as Figure 5 As shown, near the end of the first sealing member 30A side of the actuator body 22, the portion of the tube 24 not fixed by the fixing member 36 expands. In the initial stage of expansion, a gap is formed between the tube 24 and the constraint member 28, so that the boundary portion of the constraint body 28A and the constraint end 29 of the constraint member 28 does not bend radially outward before the tube 24 contacts the constraint member 28.

[0064] When the internal pressure of pipe 24 rises, such as Figure 6 As shown, near the end of the first sealing member 30A, the restraining body portion 28A is pressed by the tube 24 and bent radially outward. Furthermore, it is preferably configured such that, at the maximum internal pressure of the tube 24, the outer diameter A2 of the portion where the restraining end 29 is located is within 160% of the outer diameter A1 of the outermost part of the bamboo shoot 53. The restraining member 28 is bent in such a manner that the portion corresponding to the fixing member 36 remains unchanged, while the portion not fixed by the fixing member 36 is bent radially outward.

[0065] In the fluid pressure actuator 20 of this embodiment, the restraining end 29 is fixed to the outer surface of the tube 24 at a position radially outward of the outer surface corresponding to the portion of the tube 24 that is not inserted into the insertion portion 32B. Therefore, as described above, when the actuator body 22 expands, the degree of deformation of the restraining member 28 can be reduced, thereby suppressing the load.

[0066] In addition, in this embodiment, the bamboo shoot-shaped portion 52 expands in diameter gradually from the top end 52A side toward the base end 52C side at an angle, so that the constraint end 29 can be smoothly deformed and arranged along the outside of the insertion portion 32B.

[0067] In addition, during the initial expansion phase, a gap is formed between the tube 24 and the constraint member 28, thus reducing the burden on the boundary portion of the constraint body 28A and the constraint end 29 of the constraint member 28 before the tube 24 contacts the constraint member 28.

[0068] In addition, such as Figure 8As shown, in the conventional structure, before the action, the tube 24 contacts the constraint body 28A of the constraint member 28, therefore... Figure 9 As shown, from the initial stage of expansion, the constraint member 28 bends radially outward, and the load increases.

[0069] The embodiments of this disclosure have been described above with reference to the accompanying drawings. It is obvious to those skilled in the art that this disclosure pertains to that they can conceive of various modifications or applications within the scope of the technical concept described in the claims, and it should be understood that these modifications or applications are also within the protection scope of this disclosure.

[0070] The entire contents of Japanese Patent Application No. 2024-026898, filed on February 26, 2024, are incorporated herein by reference.

[0071] All documents, patent applications and technical standards described in this specification are incorporated herein by reference to the same extent as their respective specific and separately described instances.

Claims

1. A fluid pressure actuator, wherein, This fluid pressure actuator features: A cylindrical tube that expands and contracts according to the pressure of the fluid; A sleeve that covers the outer circumferential surface of the tube, restricting the tube from elongating axially due to the expansion of the tube and allowing the tube to expand radially due to the expansion of the tube; A pair of sealing members having insertion portions that are inserted into one and the other end of the tube from the top end towards the axial direction of the tube, respectively, the pair of sealing members sealing the end of the tube; A long, restraining member, extending radially outward from one side of the axial direction and radially inward from the outer side of the tube and the inner side of the sleeve, is capable of resisting axial compression and bending in a direction intersecting the axial direction; and A fixing member, which fixes the sleeve and the constraint member from the outside of the sleeve toward the insertion part at a position corresponding to one end of the constraint member, i.e., the constraint end. The constraint end is fixed to the outer surface of the tube at a position radially outward from the outer surface of the insertion portion corresponding to the portion of the tube not inserted into the insertion portion before bending.

2. The fluid pressure actuator according to claim 1, wherein, At maximum internal pressure, the maximum diameter of the tube is within 160% of the diameter of the portion of the insertion part where the constraint end is located.

3. The fluid pressure actuator according to claim 1, wherein, The diameter of the insertion portion increases as it moves from the tip toward the base.

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