Fluid pressure actuator

Abstract

To provide a fluid pressure actuator capable of further improving durability while preventing a net of a sleeve near a constraint member from being wider.SOLUTION: A fluid pressure actuator includes an actuator body part 100, and a sealing mechanism 200 for sealing an end of the actuator body part 100 in an axial direction DAX of the actuator body part 100, the sealing mechanism 200 including a sealing member 210 through which the actuator body part 100 is inserted, a caulking ring 230 provided on an outer peripheral face of the actuator body part 100 inserted through the sealing member 210 for constraining the actuator body part 100, and a locking ring 220 for locking a sleeve to the sealing member 210, the sealing member 210 including a trunk part 212 through which a tube 110 is inserted, the trunk part 212 having an outer diameter larger than an inner diameter of the tube 110 which is part not inserted through the trunk part 212.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a fluid pressure actuator that expands and contracts a tube using a gas or a liquid, and more specifically, to a so-called McKibben type fluid pressure actuator.

Background Art

[0002] Conventionally, as a fluid pressure actuator that expands and contracts a tube as described above, a structure (so-called McKibben type) having a rubber tube (tubular body) that expands and contracts by air pressure and a sleeve (mesh reinforcing structure) that covers the outer peripheral surface of the tube has been widely used.

[0003] Both ends of the actuator main body portion composed of the tube and the sleeve are sealed using a sealing member formed of metal.

[0004] The sleeve is a tubular structure body in which high-tensile fibers such as polyamide fibers or metal cords are woven, and regulates the expansion movement of the tube within a predetermined range.

[0005] In order to prevent the sleeve from coming off from the sealing member due to the load during the operation of such a McKibben type fluid pressure actuator, a locking member (locking ring) is used to lock the sleeve to the flange portion formed on the sealing member, and a restraining member (crimping ring) is used to crimp both ends of the actuator main body portion. Such a structure is known (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] The McKibben type fluid pressure actuator as described above may be used in an environment where expansion and contraction are continuously repeated an extremely large number of times (for example, about 10,000 to 100,000 times).

[0008] In such a case, since both end portions in the axial direction of the tube near the restraint member expand relatively greatly in the radial direction, the mesh of the sleeve near the restraint member is widened and enlarged.

[0009] Then, at the portion where the mesh of the sleeve has widened, both end portions in the axial direction of the tube near the restraint member become more likely to expand. When the operations of expansion and contraction are repeated many times, finally, these both end portions take a shape bulging like a gourd, and the durability is reduced.

[0010] Therefore, the following disclosure has been made in view of such a situation, and an object thereof is to provide a fluid pressure actuator that can prevent the mesh of the sleeve near the restraint member from widening and further improve the durability.

Means for Solving the Problem

[0011] One aspect of the present disclosure is a fluid pressure actuator including a cylindrical tube that expands and contracts by the pressure of a fluid, and an actuator main body portion constituted by a sleeve that covers the outer peripheral surface of the tube and is formed by knitting a cord oriented in a predetermined direction, and a sealing mechanism that seals an end portion of the actuator main body portion in the axial direction of the actuator main body portion. The sealing mechanism includes a sealing member through which the actuator main body portion is inserted, a restraint member provided on the outer peripheral surface of the actuator main body portion inserted through the sealing member to restrain the actuator main body portion, and a locking member that locks the sleeve to the sealing member. The sealing member includes a body portion through which the tube is inserted, and the outer diameter of the body portion is larger than the inner diameter of the portion of the tube that is not inserted through the body portion.

Effect of the Invention

[0012] According to the above-described fluid pressure actuator, it is possible to prevent the mesh of the sleeve near the restraint member from spreading, and further improve the durability.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments will be described with reference to the drawings. In addition, the same or similar reference numerals are given to the same functions and configurations, and the description thereof will be omitted as appropriate.

[0015] (1) Overall Schematic Configuration of the Fluid Pressure Actuator FIG. 1 is a side view of the fluid pressure actuator 10 according to the present embodiment. As shown in FIG. 1, the fluid pressure actuator 10 includes an actuator main body portion 100, a sealing mechanism 200, and a sealing mechanism 300.

[0016] The sealing mechanisms 200 and 300 seal both ends of the actuator main body portion 100 in the axial direction D AX Specifically, the sealing mechanism 200 includes a sealing member 210 and a caulking ring 230. The sealing member 210 is in the axial direction D of the actuator main body portion 100 AXSeal the end. Also, the caulking ring 230 caulks (which may be expressed as "crimps") the actuator main body 100 together with the sealing member 210. On the outer peripheral surface of the caulking ring 230, an indentation 231, which is a mark where the caulking ring 230 has been caulked by a jig, is formed.

[0017] The difference between the sealing mechanism 200 and the sealing mechanism 300 is whether or not a fluid connection port 211a is provided.

[0018] The actuator main body 100 is composed of a tube 110 and a sleeve 120. Fluid flows into the actuator main body 100 through the connection port 211a.

[0019] The actuator main body 100 contracts in the axial direction D of the actuator main body 100 due to the inflow of fluid into the tube 110 AX and expands in the radial direction D R In addition, the actuator main body 100 expands in the axial direction D of the actuator main body 100 due to the outflow of fluid from the tube 110 AX and contracts in the radial direction D R Due to such a change in the shape of the actuator main body 100, the fluid pressure actuator 10 exhibits its function as an actuator.

[0020] 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. In particular, the fluid pressure actuator 10 has high durability that can withstand even high-pressure hydraulic drive applied to the actuator main body 100.

[0021] Also, such a fluid pressure actuator 10 is of the so-called McKibben type and can be applied not only for artificial muscles but also preferably for the limbs (such as upper limbs and lower limbs) of robots that require higher capabilities (contracting force).

[0022] Furthermore, the fluid pressure actuator 10 can also be used as a body-worn power assist device, a walking assist device, a training device such as muscle strength, etc.

[0023] FIG. 2 is a partially exploded perspective view of the fluid pressure actuator 10. As shown in FIG. 2, the fluid pressure actuator 10 includes an actuator main body portion 100 and a sealing mechanism 200.

[0024] As described above, the actuator main body portion 100 is composed of a tube 110 and a sleeve 120.

[0025] The tube 110 is a cylindrical tubular body that expands and contracts by the pressure of a fluid. The tube 110 is made of an elastic material such as butyl rubber in order to repeat contraction and expansion by the fluid. The inner diameter Φ10 (see FIG. 4) of the tube 110 is not particularly limited, but in this embodiment, it is about 9 mm.

[0026] When the fluid pressure actuator 10 is hydraulically driven, the material of the tube 110 may be at least one selected from the group consisting of NBR (nitrile rubber) with high oil resistance, hydrogenated NBR, chloroprene rubber, and epichlorohydrin rubber.

[0027] The sleeve 120 is cylindrical 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 a diamond shape is repeated as the oriented cords intersect. By having such a shape, the sleeve 120 undergoes a pantograph deformation and follows while restricting the contraction and expansion of the tube 110.

[0028] 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, it is not limited to such types of fiber cords. For example, high-strength fibers such as PBO fiber (polyparaphenylene benzobisoxazole) or a metal cord composed of extremely fine filaments may also be used.

[0029] The sealing mechanism 200 seals the end portion in the axial direction D of the actuator main body portion 100. The sealing mechanism 200 is composed of a sealing member 210, a locking ring 220, and a caulking ring 230. AX The actuator main body portion 100 is inserted through the sealing member 210. As the sealing member 210, a metal such as stainless steel can be preferably used, but it is not limited to such a metal, and a hard plastic material or the like may be used.

[0030] The locking ring 220 locks the sleeve 120 to the sealing member 210. In the present embodiment, the locking ring 220 constitutes a locking member. Specifically, the sleeve 120 is folded back radially outward via the locking ring 220 (not shown in FIG. 2, see FIG. 3).

[0031] The locking ring 220 is formed with a notch portion 221 that is partially cut out so as to be engageable with the sealing member 210. As the locking ring 220, the same metal as the sealing member 210, a hard plastic material, or the like can be used. R The caulking ring 230 is provided on the outer peripheral surface of the actuator main body portion 100 inserted through the sealing member 210 and restrains the actuator main body portion 100. In the present embodiment, the caulking ring 230 constitutes a restraining member.

[0032]

[0033]

[0034] ​​The caulking ring 230 caulks the actuator main body 100 together with the sealing member 210. As the caulking ring 230, metals such as aluminum alloy, brass, and iron can be used. When the caulking ring 230 is caulked by a caulking jig, an indentation 231 (see FIG. 1) is formed.

[0035] The caulking jig is not particularly limited, but the actuator main body 100 is restrained by caulking a plurality of dies (for example, dies divided into seven on the circumference) that come into contact with the outer peripheral surface of the caulking ring 230 radially inward, and a linear indentation 231 along the axial direction D AX is formed.

[0036] (2) Configuration of the Sealing Mechanism Next, with reference to FIG. 3, the specific configuration of the sealing mechanism 200 will be described. FIG. 3 is a partial cross-sectional view along the axial direction D AX of the sealing mechanism 200.

[0037] As shown in FIG. 3, the sealing member 210 includes a head portion 211, a body portion 212, and a neck portion 213.

[0038] The head portion 211 is provided outside the body portion 212 in the axial direction D AX . A connection port 211a is formed in the head portion 211.

[0039] A hose (pipe line) connected to a driving pressure source of the fluid pressure actuator 10, specifically, a gas or liquid compressor, etc., is connected to the connection port 211a.

[0040] The body portion 212 is a portion through which the tube 110 (see FIGS. 1 and 2) is inserted. Specifically, the body portion 212 contacts the inner peripheral surface of the tube 110 inserted into the sealing member 210.

[0041] At least a part of the body portion 212, specifically, the axially inner end portion of the body portion 212 in the axial direction D AX is in the axial direction D AXIt is tapered such that the outer diameter decreases as it approaches the center. Specifically, in the axial direction D of the body portion 212 AX The inner end portion is in the axial direction D AX The tip is tapered such that the outer diameter decreases from the outside toward the inside.

[0042] On the outer peripheral surface of the body portion 212, a stepped portion 212a is formed to prevent the tube 110 from coming off the sealing member 210. The stepped portion 212a projects radially outward in the radial direction D so as to provide resistance against the pulling-out direction of the tube 110 from the body portion 212. R toward the outside.

[0043] The neck portion 213 is provided between the flange portion 214 and the head portion 211. The diameter Φ of the neck portion 213 is smaller than the diameters of the other portions of the sealing member 210. In this embodiment, the diameter of the neck portion 213 is about 13 mm. Also, the size in the radial direction D of the neck portion 213 is smaller than those of the body portion 212 and the head portion 211. R

[0044] The flange portion 214 is provided between the body portion 212 and the head portion 211, specifically, adjacent to the body portion 212 and the neck portion 213. The flange portion 214 projects convexly outward in the radial direction D from the body portion 212. More specifically, the flange portion 214 is an annular shape that projects radially outward from the outer peripheral surface of the neck portion 213. R R

[0045] In this embodiment, the diameter of the flange portion 214 is about 16 mm. As described above, since the diameter of the neck portion 213 is 13 mm, the step between the flange portion 214 and the neck portion 213 is about 1.5 mm.

[0046] Also, the flange portion 214 abuts on the end face 111 of the tube 110 (not shown in FIG. 3, see FIG. 2) in the axial direction D. AX

[0047] Inside the sealing member 210, in the axial direction D AX ​​​​A through-hole 215 is formed along it. The through-hole 215 communicates with the connection port 211a, and fluid flows into the actuator main body 100 through the through-hole 215. In this embodiment, the diameter Φ of the through-hole 215 is about 5 mm.

[0048] Also, a connecting portion 216 is provided on the sealing member 210. Specifically, the connecting portion 216 is provided on the outer side in the axial direction D of the head portion 211. An engaging hole 216a is formed in the connecting portion 216 to engage members such as those constituting the device using the fluid pressure actuator 10. AX An engaging hole 216a is formed in the connecting portion 216 to engage members such as those constituting the device using the fluid pressure actuator 10.

[0049] The tube 110 is inserted into the body portion 212. As described above, the flange portion 214 abuts against the end face 111 of the tube 110. Also, the tube 110 is expanded in diameter by being inserted into the body portion 212.

[0050] Also, the stepped portion 212a bites into the inner peripheral surface of the tube 110 when the actuator main body 100 is caulked together with the sealing member 210 by the caulking ring 230, more reliably preventing the tube 110 from coming out of the body portion 212.

[0051] The locking ring 220 is provided on the outer peripheral surface of the sleeve 120, and the sleeve 120 is folded back toward the center in the axial direction D through the locking ring 220. Specifically, the sleeve 120 has a folded-back portion 120a that is folded back through the locking ring 220. Also, the folded-back portion 120a is folded back radially outward through the locking ring 220 and abuts against the inner peripheral surface of the caulking ring 230. AX The sleeve 120 has a folded-back portion 120a that is folded back through the locking ring 220. Also, the folded-back portion 120a is folded back radially outward through the locking ring 220 and abuts against the inner peripheral surface of the caulking ring 230. R Also, the folded-back portion 120a is folded back radially outward through the locking ring 220 and abuts against the inner peripheral surface of the caulking ring 230.

[0052] The caulking ring 230 fixes the actuator main body 100 to the sealing member 210 by caulking the sleeve 120 folded back through the tube 110 and the locking ring 220 together with the sealing member 210.

[0053] The axial direction D of the caulking ring 230 AXThe outer end face 232 may be located near the boundary between the head 211 and the neck 213. Specifically, the end face 232 may be positioned so as to contact the inner surface 211b of the head 211 in the axial direction D AX and may be positioned so as to contact the inner surface 211b of the head 211 in the axial direction D

[0054] (3) The diameter sizes of the sealing member 210 and the actuator main body 100 FIG. 4 is a partial cross-sectional view along the axial direction D of the sealing mechanism 200 before assembly AX In FIG. 4, only the actuator main body 100 and the sealing member 210 are shown, and the illustrations of the locking ring 220, the caulking ring 230, and the folded-back portion 120a of the sleeve 120 are omitted for convenience of explanation

[0055] As described above, the tube 110 is expanded in diameter by being inserted into the body portion 212. Therefore, the inner diameter Φ10 of the tube 110 before being expanded in diameter, in other words, the inner diameter Φ10 of the portion of the tube 110 that is not inserted into the body portion 212, is smaller than the diameter (outer diameter) of the body portion 212

[0056] That is, the outer diameter of the body portion 212 may be larger than the inner diameter Φ10 of the portion of the tube 110 that is not inserted into the body portion 212

[0057] In the present embodiment, as shown in FIG. 4, the outer diameter of the inner end of the body portion 212 in the axial direction D AX is larger than the inner diameter Φ10 of the tube 110 (about 14 mm in this embodiment). The outer diameter of the inner end of the body portion 212 is preferably 30 to 70% thicker than the inner diameter Φ10, and more preferably 40 to 50% thicker

[0058] If the outer diameter of the inner end of the body portion 212 is too thick compared to the inner diameter Φ10, when assembling the fluid pressure actuator 10, the tube 110 is likely to come off before caulking the actuator main body portion 100, resulting in a decrease in productivity. Also, the rubber (tube 110) at the caulked portion becomes too thin and is likely to become a failure core. On the other hand, if the outer diameter of the inner end of the body portion 212 is too thin compared to the inner diameter Φ10, a sufficient effect of preventing the mesh of the sleeve near the caulking ring 230 from expanding cannot be obtained.

[0059] The tube 110 is expanded by being inserted into the body portion 212 having such a diameter difference. Considering the prevention of the tube 110 from being pulled out and durability, etc., the expansion rate of the tube 110 is preferably 1.3 times or more and 1.7 times or less. The expansion rate of the tube 110 may be the ratio to the diameter of the groove bottom of the stepped portion 212a at the maximum outer diameter portion of the body portion 212 with respect to the inner diameter Φ10 of the tube 110.

[0060] Note that when the diameter of the body portion 212 is increased, the diameter of the groove bottom of the stepped portion 212a also increases. As a result, the outer diameter of the portion caulked by the caulking ring 230 can be increased, and the strength of the caulked portion can be enhanced. As a result, the diameter Φ of the through hole 215 can also be increased, which can contribute to a decrease in the flow resistance of the fluid and an improvement in the response when the fluid pressure actuator 10 operates.

[0061] (4) Function and Effect Figs. 5(a) to (d) are partial cross-sectional views and contour diagrams along the axial direction D of the sealing mechanism 200 and the sealing mechanism 200P. In Figs. 5(a) to (d), similar to Fig. 4, the illustrations of the locking ring 220, the caulking ring 230, etc. are omitted. AX Specifically, Fig. 5(a) schematically shows the shape when the actuator main body portion 100 of the sealing mechanism 200 expands. Fig. 5(b) schematically shows the shape when the actuator main body portion 100P of the conventional sealing mechanism 200P expands. Figs. 5(c) and 5(d) respectively show the contour diagrams of the sealing mechanism 200 and the sealing mechanism 200P.

[0062] ​

[0063] When the outer diameter of the body portion 212P of the sealing member 210P is the same as or smaller than the inner diameter of the tube 110P, such as in the sealing mechanism 200P, when pressure is applied to the actuator main body portion 100 and the actuator main body portion 100 expands in the circumferential direction, compared with the actuator main body portion 100P caulked to the caulking ring 230 (see FIG. 3 etc.), the outer diameter of the portion of the actuator main body portion 100 not caulked to the caulking ring 230 becomes larger. When such expansion and contraction operations are repeated, the mesh of the sleeve 120 will shift.

[0064] Therefore, when such an operation is repeated over a long period of time, the cords constituting the sleeve 120 will move closer to the non-expanding caulking ring 230 side, and the cord intervals will become narrow and dense. On the other hand, in the central side in the axial direction D AX away from the caulking ring 230, the cord intervals will widen and become sparse.

[0065] In the portion where the cord intervals become sparse, when pressure is applied, the tube 110P will expand more than other portions, and ultimately deform into a distorted shape like a bellows. Since a non-uniformly large load is applied to the cords and the tube 110P constituting the sleeve 120, the durability decreases.

[0066] In the sealing mechanism 200 according to this embodiment, such deformation of the actuator main body portion can be prevented. Specifically, as shown in FIGS. 5(a) to (d), when the actuator main body portion 100 expands, the diameter difference D1 between the diameter Φ31 of the actuator main body portion 100 inserted through the body portion 212 and the diameter Φ32 of the actuator main body portion 100 not inserted through the body portion 212 is smaller than the diameter difference D2 between the diameter Φ31P of the actuator main body portion 100P inserted through the body portion 212P and the diameter Φ32P of the actuator main body portion 100P not inserted through the body portion 212 when the actuator main body portion 100P expands.

[0067] Specifically, in the sealing mechanism 200, as described above, in the axial direction D of the body portion 212 AXMake the outer diameter of the inner end (about 14 mm) larger than the inner diameter Φ10 of the tube 110 (see Fig. 4), and while stretching the tube 110 in the radial direction D R insert it into the body portion 212 of the sealing member 210. By doing so, when the actuator main body portion 100 is not pressurized, the diameter size of the portion of the tube 110 caulked by the caulking ring 230 can be made larger in advance than the diameter size of the tube 110 of the actuator main body portion 100 not caulked by the caulking ring 230.

[0068] Therefore, even when the actuator main body portion 100 expands by pressurizing the actuator main body portion 100, the diameter difference D1 can be reduced (that is, the diameter difference D1 < the diameter difference D2 can be achieved). As a result, the deviation of the cord (thread) constituting the sleeve 120 can be reduced, and finally, the formation of a ladle shape of the shape of the actuator main body portion 100 can be suppressed.

[0069] That is, according to the fluid pressure actuator 10, it is possible to prevent the mesh of the sleeve 120 near the caulking ring 230 from spreading, and the durability can be further improved.

[0070] In this embodiment, the tube 110 is expanded in diameter by being inserted through the body portion 212 of the sealing member 210. Therefore, due to the shrinking force of the tube 110, it can be more firmly engaged with the stepped portion 212a of the body portion 212, and the pulling out of the tube 110 can be more reliably prevented.

[0071] In this embodiment, the expansion ratio of the tube 110 is preferably 1.3 times or more and 1.7 times or less. By setting such a range, it is possible to achieve both prevention of the tube 110 from being pulled out and durability while suppressing the formation of a ladle shape of the shape of the actuator main body portion 100.

[0072] In this embodiment, the inner end portion in the axial direction D of the body portion 212 AX is tapered such that the outer diameter becomes smaller as it goes toward the center in the axial direction D AX . Therefore, it is easy to insert the tube 110 into the body portion 212 while expanding the diameter of the tube 110.

[0073] (5) Other Embodiments Although the embodiments have been described above, it is obvious to those skilled in the art that the present disclosure is not limited to the description of the embodiments, and various modifications and improvements are possible.

[0074] For example, the body portion 212 of the sealing member 210 does not necessarily have to be tapered such that the outer diameter decreases as it approaches the center in the axial direction D AX That is, the outer diameter of the body portion 212 may be constant as long as it is larger than the inner diameter Φ10 of the tube 110, or a part on the outside in the axial direction D AX may be equal to or smaller than the inner diameter Φ10.

[0075] Also, the connecting portion 216 of the sealing member 210 may not be provided. That is, the connecting portion 216 may or may not be provided according to the use of the fluid pressure actuator 10. Further, a threaded portion may be formed on the connecting portion 216 so that it can be attached to and detached from the head portion 211.

[0076] In the above-described embodiment, the sleeve 120 was folded back via the locking ring 220, but the sleeve 120 does not necessarily have to be folded back to the center side in the axial direction DAX.

[0077] Although the present disclosure has been described in detail above, it is obvious to those skilled in the art that the present disclosure is not limited to the embodiments described in the present disclosure. The present disclosure can be implemented as modifications and variations without departing from the spirit and scope of the present disclosure as defined by the claims. Therefore, the description of the present disclosure is for illustrative purposes and does not have any limiting meaning for the present disclosure.

Description of Reference Numerals

[0078] 10 Fluid pressure actuator 100, 100P Actuator main body portion 110, 110P Tube 111 End face 120 sleeve 120a folded-back portion 200, 200P sealing mechanism 210 sealing member 211 head 211a connection port 211b inner surface 212, 212P body portion 212a stepped portion 213 leading portion 214 flange portion 215 through hole 216 connecting portion 216a engaging hole 220 locking ring 221 notch portion 230 caulking ring 231 indentation 232 end face 300 sealing mechanism

Claims

1. An actuator body portion composed of a cylindrical tube that expands and contracts by the pressure of a fluid, and a sleeve that covers the outer peripheral surface of the tube and incorporates a cord oriented in a predetermined direction, A sealing mechanism that seals the ends of the actuator body portion in the axial direction of the actuator body portion, A fluid pressure actuator comprising: The sealing mechanism includes: A sealing member through which the actuator body portion is inserted, A restraining member provided on the outer peripheral surface of the actuator body portion inserted through the sealing member to restrain the actuator body portion, A locking member that locks the sleeve to the sealing member, Comprising, The sealing member includes a body portion through which the tube is inserted, The outer diameter of the body portion is larger than the inner diameter of the tube in the portion where the tube is not inserted through the body portion, A stepped portion is formed on the outer peripheral surface of the body portion, The maximum outer diameter portion of the body portion is the groove bottom of the stepped portion, and the maximum outer diameter decreases toward the center in the axial direction. Fluid pressure actuator.

2. The fluid pressure actuator according to claim 1, wherein the tube is expanded in diameter by being inserted through the body portion.

3. The fluid pressure actuator according to claim 2, wherein the expansion ratio of the tube is 1.3 times or more and 1.7 times or less.

4. The fluid pressure actuator according to any one of claims 1 to 3, wherein at least a part of the body portion is tapered such that the outer diameter decreases toward the center in the axial direction.

Images