Hydraulic actuator

Abstract

A hydraulic actuator 20 comprises: a cylindrical tube 24; a sleeve 26 which covers the outer peripheral surface of the tube 24 and that, by expanding the tube, widens the tube in the radial direction while restricting extension of the tube in the axial direction; a pair of sealing members 32 in which is formed an insertion part 32B having a tapered section 49 having a diameter that becomes smaller approaching the depth side of insertion, and which seals a tube end section; a constraining member 28 which is provided so as to span from one side to the other side of the pair of sealing members 32, which is disposed so as to be inclined such that a constraining end section 29 runs along the tapered section 49, which resists compression in the axial direction, and which can be deformed in an intersecting direction intersecting the axial direction; and a fixing member 36 which fixes the sleeve 26 and the constraining member 28 to the insertion part 32B from the outside of the sleeve 26 at a position corresponding to the constraining end section 29 of the constraining member 28.

Description

Fluid Pressure Actuator

[0001] The present invention relates to a fluid pressure actuator.

[0002] Japanese Patent Application Laid-Open Publication No. 2021-088999 discloses a fluid pressure actuator that includes a cylindrical tube that expands and contracts due to fluid pressure, an elastic structure made of woven fiber cords oriented in a predetermined direction, a sleeve that covers the outer surface of the tube, and a sealing member that seals the axial end of the tube, and includes a restraining member that is provided inside the sleeve from one end to the other end in the axial direction, and the restraining member resists compression along the axial direction and is deformable in a direction perpendicular to the axial direction.

[0003] In the configuration described in JP 2021-088999 A, there is a concern that the position of the restraint member may easily shift when a force is applied to the tip of the fluid pressure actuator, particularly when the direction of the force received from the object intersects with the axial direction (for example, when the axial direction of the fluid pressure actuator is horizontal and the object is lifted).

[0004] SUMMARY OF THE INVENTION An object of the present invention is to provide a fluid pressure actuator that reduces displacement of a restraining member due to the application of force.

[0005] a pair of sealing members into which one and other axial ends of the tube are inserted from the tip end, each having an insertion section with a tapered portion that becomes smaller in diameter toward the back of the insertion section, and sealing the tube ends; a constraint member provided radially inside the sleeve and spanning from one side to the other of the pair of sealing members, with a constraint end inclined so as to follow the tapered portion, resisting compression along the axial direction and deformable in a direction intersecting the axial direction; and a fixing member that fixes the sleeve and the constraint member to the insertion section from the outside of the sleeve at a position corresponding to the constraint end of the constraint member.

[0006] In the fluid pressure actuator of the first aspect, a tapered portion is formed in the insertion portion of the sealing member that seals the end of the tube, the diameter of which decreases toward the innermost portion of the insertion. The restraining end of the restraining member is disposed at an angle so as to follow the tapered portion, and is fixed to the insertion portion from the outside by a fixing member.

[0007] In this way, by fixing the restraining end of the restraining member to the insertion portion using a portion with a smaller diameter than the expanding and contracting portion of the fluid pressure actuator, the force acting in the circumferential direction on the restraining end can be reduced.

[0008] In a second aspect of the fluid pressure actuator, the sealing member has a base end portion on the opposite side of the insertion portion from the side where the tube is inserted, the base end portion having a larger diameter than the insertion portion, and the insertion portion has a small diameter portion at the boundary with the base end portion that continues from the tapered portion and has a constant diameter in the axial direction, and the restraint end portion is arranged to extend from the small diameter portion.

[0009] According to the fluid pressure actuator of the second aspect, a small diameter portion is formed between the base end portion of the sealing member and the insertion portion, and the restraining end portion is extended up to the small diameter portion, allowing for stable fixation.

[0010] A fluid pressure actuator of a third aspect is the fluid pressure actuator of the second aspect, wherein the restraint end portion is disposed so as to abut against a step between the small diameter portion and the base end portion.

[0011] According to the fluid pressure actuator of the third aspect, it is possible to prevent the restraint end from shifting in the axial direction.

[0012] A fluid pressure actuator of a fourth aspect is the fluid pressure actuator of the second or third aspect, further comprising a locking wire that fixes the restraint end to the small diameter portion via the sleeve.

[0013] According to the fluid pressure actuator of the fourth aspect, the restraining end portion can be more firmly fixed by the locking wire.

[0014] A fluid pressure actuator of a fifth aspect is the fluid pressure actuator of any one of the first to fourth aspects, wherein the restraint end portion is arranged in contact with the insertion portion at the tapered portion.

[0015] According to the fluid pressure actuator of the fifth aspect, the restraint end portion is in contact with the insertion portion without the intervention of a tube, so that a stronger fixation can be achieved.

[0016] According to the present invention, it is possible to reduce displacement of the restraining member due to the application of force.

[0017] FIG. 4 is a plan view of a fluid pressure actuator according to an embodiment of the present disclosure. FIG. 5 is an exploded perspective view of one axial end side of a fluid pressure actuator according to an embodiment of the present disclosure. FIG. 6 is a perspective view illustrating a sealing member connector according to an embodiment of the present disclosure. FIG. 7 is a cross-sectional view of a connection portion between a sealing member connector and an actuator main body according to an embodiment of the present disclosure. FIG. 8 is a cross-sectional view taken along line 5-5 of FIG. 4. FIG. 9 is a cross-sectional view taken along line 6-6 of FIG. 4.

[0018] Hereinafter, embodiments for realizing the technology of the present disclosure will be described in detail with reference to the drawings.

[0019] In addition, components and processes that perform the same actions and functions are given the same reference numerals throughout the drawings, and duplicated explanations may be omitted as appropriate. Furthermore, the present disclosure is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the purpose of the present disclosure.

[0020] As shown in FIG. 1, a fluid pressure actuator 20 according to an embodiment of the present disclosure includes an actuator body 22, a first sealing member 30A, and a second sealing member 30B.

[0021] As shown in FIG. 2 , the actuator main body 22 includes a tube 24, a sleeve 26, and a restraining member 28. The tube 24 is cylindrical and elastically deformable, expanding and contracting with changes in the pressure of the fluid inside. The axial direction S of the tube 24 is referred to as the "axial direction S." The tube 24 may be made of an elastic material such as butyl rubber. Air may be used as the fluid supplied to the tube 24, in which case the fluid pressure actuator 20 becomes a pneumatic actuator. Note that when the fluid pressure actuator 20 is hydraulically driven, it is preferable to use at least one material selected from the group consisting of highly oil-resistant NBR (nitrile rubber), hydrogenated NBR, chloroprene rubber, and epichlorohydrin rubber.

[0022] The sleeve 26 is cylindrical and covers the outer periphery of the tube 24. The sleeve 26 is an elastic structure made by weaving fiber cords oriented in a predetermined direction, and the oriented cords intersect at a predetermined angle θ with respect to the axial direction S. By having such a shape, the sleeve 26 undergoes pantograph deformation that changes the angle θ, and follows the contraction and expansion of the tube 24 while regulating this contraction and expansion.

[0023] It is preferable to use fiber cords made of aromatic polyamide (aramid fiber) or polyethylene terephthalate (PET) as the cords constituting the sleeve 26. However, the cords are not limited to these types of fiber cords, and other high-strength fiber cords such as PBO fiber (polyparaphenylene benzobisoxazole) may also be used.

[0024] The restraining member 28 is provided between the tube 24 and the sleeve 26. The restraining member 28 is in the form of a long plate, and is arranged such that its longitudinal direction is along the axial direction S of the tube 24. The restraining member 28 covers part of the outer periphery of the tube 24 and is arranged from one end of the tube 24 to the other end.

[0025] The restraining member 28 includes a restraining main body portion 28A and a restraining end portion 29. The restraining main body portion 28A is a portion that is arranged along the axial direction S of the tube 24. The restraining end portion 29 is formed at both ends of the restraining member 28. The restraining end portion 29 has a bent shape having an inclined portion 29A and a tip portion 29B. The inclined portion 29A is bent so as to be inclined radially inward as it extends from the restraining main body portion 28A toward the end. The tip portion 29B is continuous with the inclined portion 29A and extends so as to be parallel to the restraining main body portion 28A.

[0026] The restraining member 28 is formed of a material that does not expand or contract when pressurized, and is capable of bending and deforming in the direction in which its ends approach each other. A so-called leaf spring can be used as the restraining member 28. The dimensions of the leaf spring are determined according to the size of the fluid pressure actuator 20, the required gripping force, and other factors. The material of the leaf spring is not particularly limited, but typically, any material that is easily bendable and resistant to compression, such as a metal such as stainless steel, may be used. Alternatively, the leaf spring may be formed of a thin plate of carbon fiber reinforced plastic (CFRP).

[0027] The first sealing member 30A includes a sealing member connector 32, a locking wire 34, and a fixing member 36.

[0028] 3 and 4, the sealing member connector 32 has an integrally molded base end portion 32A and an insertion portion 32B. The base end portion 32A is generally rectangular parallelepiped with a diameter larger than the outer diameter of the tube 24, and the insertion portion 32B extends in the axial direction S from the center of one end of the base end portion 32A. The insertion portion 32B has, in order from the base end 32A side, a small diameter portion 48, a tapered portion 49, a large diameter portion 50, and a bamboo-like portion 52.

[0029] The shoot portion 52 protrudes from the distal end of the insertion portion 32B, and the tube 24 is inserted from the distal end of the shoot portion 52. The shoot portion 52 is tapered in three steps, with the diameter increasing toward the proximal end 32A. The large diameter portion 50 is formed continuously with the proximal end 32A side of the shoot portion 52 and is a disk-shaped portion with a larger diameter than the shoot portion 52. A step 42 is formed between the large diameter portion 50 and the shoot portion 52.

[0030] The tapered portion 49 is formed continuously from the large diameter portion 50 on the base end 32A side of the large diameter portion 50 (the back side of the insertion portion 32B), and has a tapered shape that becomes smaller in diameter toward the base end 32A side. The end of the tapered portion 49 on the base end 32A side has a smaller diameter than the tip of the bamboo portion 52.

[0031] The small diameter portion 48 is formed between the tapered portion 49 and the base end 32A, and has the same diameter from the tapered portion 49 to the base end 32A. The outer diameter of the small diameter portion 48 is smaller than the tip of the barbed portion 52. A step 35 is formed between the small diameter portion 48 and the base end 32A.

[0032] The sealing member connector 32 is preferably made of a metal such as stainless steel, but is not limited to such a metal and may be made of a hard plastic material or the like.

[0033] 4, the sealing member connector 32 has a flow path R formed in the central portion of the insertion portion 32B as viewed in the axial direction S, which extends in the axial direction S and is in communication with a connection hole H on the side surface of the base end portion 32A (see also FIG. 7). An air supply hose (not shown) is connected to the connection hole H, and compressed air is supplied to the flow path R.

[0034] The restraining end 29 of the restraining member 28 is disposed in a position in the axial direction S corresponding to the tapered portion 49 and small diameter portion 48 of the sealing member connector 32. The restraining end 29 is in direct contact with the insertion portion 32B without the tube 24 (see FIG. 4). The inclined portion 29A of the restraining end 29 is disposed along the tapered portion 49 so that the end side is inclined radially inward. The tip end 29B of the restraining end 29 extends from the inclined portion 29A and is disposed along the small diameter portion 48, with the end face abutting against the step 35 between the base end 32A and the small diameter portion 48.

[0035] The locking wire 34 is formed into a ring shape by winding the wire multiple times, and is wound around the outside of the sleeve 26 so as to sandwich the sleeve 26 between the small diameter portion 48 and the locking wire 34. The sleeve 26 is also folded back onto the outer periphery via the locking wire 34. This allows the sleeve 26 to be locked to the sealing member connector 32. A metal wire can be used as the locking wire 34.

[0036] The fixing member 36 is disposed so as to cover the insertion portion 32B on the outer periphery of the actuator main body 22. As shown in Fig. 5, the barb portion 52, the tube 24, the restraint main body 28A of the restraint member 28, the sleeve 26 (before folding), and the sleeve 26 (after folding) are disposed in the portion of the fixing member 36 corresponding to the barb portion 52 on the inside. As shown in Fig. 6, the small diameter portion 48, the tip end 29B of the restraint member 28, the sleeve 26 (before folding), the locking wire 34, and the sleeve 26 (after folding) are disposed in the portion of the fixing member 36 corresponding to the small diameter portion 48 on the inside.

[0037] The tube 24 , restraining member 28 , and sleeve 26 can be secured to the sealing member connector 32 by crimping the securing member 36 radially inward.

[0038] Next, the assembly procedure for the fluid pressure actuator 20 in this embodiment will be described.

[0039] <Assembly of the fluid pressure actuator 20>

[0040] As shown in FIGS. 2 and 5, at one end of the fluid pressure actuator 20 in this embodiment, the first sealing member 30A and the actuator main body 22 are assembled as follows.

[0041] First, the tube 24 is inserted into the insertion portion 32B of the sealing member connector 32 until one end of the tube 24 abuts against the step 42. Next, the restraining member 28 is positioned so that the inclined portion 29A of the restraining end portion 29 is arranged along the tapered portion 49, the tip portion 29B of the restraining end portion 29 is arranged along the small diameter portion 48, and the end face of the tip portion 29B abuts against the step 35.

[0042] Next, the sleeve 26 is placed over the tube 24 and the base end 32A of the sealing member connector 32 to cover the outer surface of the restraint member 28, and the locking wire 34 is wound around the sleeve 26 from the radial outside and attached to the position of the small diameter portion 48.

[0043] Next, the sleeve 26 is folded back onto the insertion portion 32B of the sealing member connector 32 so that the locking wire 34 is on the inside, and the fixing member 36 is positioned so that it spans from the radial outside of the sleeve 26 to the end of the small diameter portion 48 of the insertion portion 32B, and is then crimped and fixed in place. As a result, the tube 24, the restraining member 28, and the sleeve 26 are fixed to the sealing member connector 32 on one side of the actuator body 22 in the axial direction S.

[0044] Next, on the other side in 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.

[0045] By the above procedure, one side and the other side of the tube 24 are sealed with the first sealing member 30A and the second sealing member 30B, and the fluid pressure actuator 20 is assembled.

[0046] Next, the operation of the fluid pressure actuator 20 in the present disclosure will be described.

[0047] <Operation of the fluid pressure actuator 20>

[0048] As shown in FIG. 7, the fluid pressure actuator 20 is used with a first sealing member 30A on one end side fixed and a second sealing member 30B on the other end side being a free end.

[0049] When compressed air is introduced through the connection hole H, the pressure inside the fluid pressure actuator 20 increases. Due to the increase in internal pressure, the tube 24 elastically deforms and expands, and the sleeve 26 undergoes pantograph deformation so that the angle θ increases, and a force acts in a direction that shortens the length of the actuator main body 22. At this time, because the shortening of the outer peripheral side wall on which the restraining member 28 of the actuator main body 22 is arranged is restricted, the outer peripheral wall of the actuator main body 22 on the side where the restraining member 28 is not arranged shortens as viewed in the axial direction S. This causes the restraining member 28 to flex and deform, and the entire actuator main body 22 bends as shown by the two-dot chain line in FIG. 7 .

[0050] In the present disclosure, the restraint member 28 has a length in the width direction, and therefore is unlikely to bend in any direction other than the thickness direction, i.e., the direction intersecting the axial direction S of the first sealing member 30A and the second sealing member 30B (hereinafter referred to as the "intersecting direction X"). In other words, as shown in FIG. 7 , the restraint member 28 bends in a direction toward the axis of the tube 24.

[0051] If a plurality of fluid pressure actuators 20 that bend in this manner are provided, the plurality of fluid pressure actuators 20 can hold an object.

[0052] Next, the actions and effects of the fluid pressure actuator 20 according to the present disclosure will be described.

[0053] <Action and effect>

[0054] In the fluid pressure actuator 20 of the present disclosure, the restraining end 29 of the restraining member 28 is fixed to the insertion portion 32B using a tapered portion 49 and a small diameter portion 48 that are smaller in diameter than the actuator main body 22, which is the portion that expands and contracts of the fluid pressure actuator 20. This makes it possible to reduce the force acting in the circumferential direction on the restraining end 29, and to reduce displacement of the restraining member 28 due to the application of force.

[0055] In this embodiment, an example has been described in which the restraining end portion 29 has the tip portion 29B that is disposed along the small diameter portion 48, but the tip portion 29B is not necessarily required. By providing the tip portion 29B and disposing it along the small diameter portion 48 as in this embodiment, the restraining member 28 can be fixed more stably. Furthermore, by disposing the tip portion 29B so that it abuts against the step 35, it is possible to prevent the restraining member 28 from shifting in the axial direction.

[0056] In addition, in this embodiment, the restraining end portion 29 is in direct contact with the insertion portion 32B without using the tube 24. Therefore, the restraining member 28 can be fixed to the insertion portion 32B more firmly than when the tube 24 is used.

[0057] The above describes an embodiment of the present disclosure with reference to the accompanying drawings. However, it is clear that a person with ordinary knowledge in the field of technology to which the present disclosure pertains can conceive of various modifications or applications within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present disclosure.

[0058] Japanese Patent Application No. 2023-208688, filed on December 11, 2023, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

a sleeve covering the outer circumferential surface of the tube and expanding the tube radially while restricting axial extension as the tube expands; a pair of sealing members into which one and other axial ends of the tube are inserted from their respective tip ends, forming an insertion section having a tapered portion which becomes smaller in diameter toward the back of the insertion, and sealing the tube ends; a restraining member provided radially inside the sleeve, spanning from one side to the other of the pair of sealing members, with a restraining end obliquely positioned along the tapered portion, resisting compression along the axial direction and deformable in a transverse direction which intersects the axial direction; and a fixing member fixing the sleeve and the restraining member to the insertion section from the outside of the sleeve at a position corresponding to the restraining end of the restraining member.

2. A fluid pressure actuator as described in claim 1, wherein the sealing member has a base end portion with a larger diameter than the insertion portion on the side opposite the side of the insertion portion where the tube is inserted, and the insertion portion has a small diameter portion at the boundary with the base end portion that continues from the tapered portion and has a constant diameter in the axial direction, and the restraint end portion is arranged to extend into the small diameter portion.

3. The fluid pressure actuator according to claim 2, wherein the restraint end is disposed so as to abut against a step between the small diameter portion and the base end.

4. The fluid pressure actuator according to claim 2, further comprising a locking wire for fixing said restraining end to said reduced diameter portion via said sleeve.

5. A fluid pressure actuator according to any one of claims 1 to 4, wherein the restraint end is disposed in contact with the insertion portion at the tapered portion.

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