Actuator

Abstract

Actuator (10) comprising the following: an actuator body (11) with several artificial muscles (12), each artificial muscle (12) having an elastic tube (13) and a braided tube (15) covering an outside of the elastic tube (13); a cylindrical outer body (21, 22) which is attached to an end section of the actuator main body (11); a connecting section (23) provided in the cylindrical outer body (21, 22), wherein the connecting section (23) connects the elastic tube (13) to the braided tube (15) and connects the cylindrical outer body (21, 22) to the artificial muscles (12); and a connecting element (41, 42) to which the cylindrical outer body (21, 22) is inserted, wherein a locking element (51) is provided on the connecting element (41, 42) and fastens the cylindrical outer body (21, 22) and the connecting element (41, 42) to each other, and wherein a length in an axial direction from an end side of the actuator main body (11) to a surface of the connecting section (23) is greater than a length in an axial direction from the end side of the actuator main body (11) to a snap point where the locking member (51) snaps into the cylindrical outer body (21, 22).

Description

TECHNICAL AREA

[0001] The present invention relates to an actuator with several artificial muscles bundled together, each artificial muscle having an elastic tube. STATE OF THE ART

[0002] Patent specification 1 discloses an actuator for use in robots, comprising an elastic tube or casing made of hollow, flexible rubber and a tube-like network covering the outer surface of the casing. This actuator is used, for example, to swing an arm segment connected to a pin. Furthermore, an actuator with several artificial muscles bundled together has been developed and assembled for use in care devices, rehabilitation devices, and the like.

[0003] Patent specification 2 discloses a flexible actuator with several tube-like links. Each tube-like link has a hollow elastic extendable element made of rubber or the like, and a braided structure enclosing the elastic extendable element. The braided structure is formed by polyester fibers, the elastic extendable element has a closure element fixed to each end section, and the closure element is provided with a connecting passage that communicates with the interior of the elastic extendable element.Patent specification 3 discloses an artificial muscle limb comprising: an expansion body formed by a rubber tube surrounded by a braided cord, and a contraction body formed by another braided cord; the outer circumferential area of ​​the braided cord of the contraction body is shorter than the outer circumferential length of the braided cord of the expansion body. The rubber tubes used for the expansion body have circular or star-shaped cross-sections, and polyester threads are used for each braided cord. US 5,079,999 A describes a flexible actuator comprising a plurality of elastic, stretchable elements arranged in parallel and axially stretchable when a pressurized fluid is applied to them. The actuator further comprises connecting elements arranged to enclose the elastic, stretchable elements and connect their respective ends. The actuator includes an elastic element positioned between the connecting elements and surrounding the elastic, stretchable elements to resist the tensile forces acting upon them and to prevent bending. Writings on the State of Technology Patents Patent specification 1: Unexamined Japanese patent application publication no. S 60-132103 Patent specification 2: Unexamined Japanese patent application publication no. H03-028507 Patent specification 3: Unexamined Japanese patent application publication no. 2010-279689 Brief description of the invention; problems to be solved by the invention

[0004] The actuator described in patent specification 1 comprises a single artificial muscle consisting of an elastic tube and a tubular network covering the outside of the elastic tube. For this reason, a greater degree of expansion and contraction in a radial direction of the elastic tube is required to oscillate the arm segment to a predetermined angle of oscillation; however, the poor tensile strength of the elastic tube limits the extent of expansion and contraction.

[0005] If, in contrast, the actuator has several tubular links bundled together, as described in Patent 2, the degree of elongation in an axial direction of the actuator can be greatly increased without requiring an increase in the degree of expansion and contraction of each tubular link. However, the actuator described in Patent 2 has a sealing element that is inserted into and fixed in each end section of the tubular link, with both end sections of the tubular link bundled together by a fastening strap, and the fastening strap and the sealing element further fastened to each other by a bolt. For this reason, tubular links with a small diameter cannot be used, and miniaturization of the actuator cannot be achieved.One object of the present invention is to achieve the miniaturization of the actuator. MEANS TO SOLVE THE PROBLEM

[0006] According to one aspect of the present invention, an actuator comprises: an actuator body with several artificial muscles, each artificial muscle having an elastic tube and a braided tube covering an outer surface of the elastic tube; a cylindrical outer surface body attached to an end section of the actuator body; a connecting section provided in the cylindrical outer surface body, the connecting section connecting the elastic tube to the braided tube and connecting the cylindrical outer surface body to the artificial muscles;and a connecting element up to which the cylindrical outer body is inserted, wherein a locking element is provided on the connecting element and fastens the cylindrical outer body and the connecting element to each other, and wherein a length in an axial direction from an end face of the actuator main body to a surface of the connecting section is more than a length in an axial direction from the end face of the actuator main body to a snap point at which the locking element snaps into the cylindrical outer body.

[0007] According to a further aspect of the present invention, an actuator comprises: an actuator body with several artificial muscles, each artificial muscle having an elastic tube and a braided tube covering an outer surface of the elastic tube; a first cylindrical outer surface body attached to one end section of the actuator body; a second cylindrical outer surface body attached to the other end section of the actuator body; a connecting section provided in the first cylindrical outer surface body and the second cylindrical outer surface body, the connecting section connecting the elastic tube to the braided tube and connecting the first and second cylindrical outer surface bodies to the artificial muscles; a first connecting element to which the first cylindrical outer surface body is inserted;and a second connecting member up to which the second cylindrical outer body is inserted, wherein a locking member is provided for joining the first cylindrical outer body and the first connecting member to the first connecting member, and a locking member is provided for joining the second cylindrical outer body and the second connecting member to the second connecting member, and wherein a length in an axial direction from an end face of the actuator main body to a surface of the connecting section is more than a length in the axial direction from one of the end faces of the actuator main body to a snap point at which one of the locking members snaps into the cylindrical outer body. EFFECTS OF THE INVENTION

[0008] The actuator comprises a main body containing multiple artificial muscles and a cylindrical outer body attached to one end of the main body. Because the cylindrical outer body and the artificial muscles are connected by a connecting section formed within the cylindrical outer body, links used for fluid supply can be omitted, and fluid can be fed directly into the elastic tubing. This allows the actuator to be configured using small-diameter artificial muscles, thus miniaturizing the actuator. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a partial cross-sectional view showing an actuator main body with cylindrical outer bodies attached to its respective end sections; Fig. 2 (A) is an enlarged cross-sectional view showing part of the actuator main body; Fig. 2 (B) is a cross-sectional side view of Fig. 2 (A); Fig. Figure 3 is an enlarged cross-sectional view of section "A" of Fig. 2 (A); Fig. Figure 4 is a perspective view showing a cross-section of an artificial muscle; Fig. 5 (A) is a front view showing the actuator attached to a vibrating link and in a stretched state; Fig. 5 (B) is a front view showing the actuator attached to an oscillating member and in a contracted state; Fig. Figure 6 is a partial cross-sectional view showing the actuator with connecting elements attached to its respective end sections; and Fig. Figure 7 is a cross-sectional view showing a variation of a first connecting element attached to an end section of the actuator. DETAILED DESCRIPTION OF PREFERRED EXECUTION FORMS

[0009] In the following, an embodiment of the present invention is described in detail based on the drawings. As shown in Fig. As shown in Figure 1, an actuator 10 of the present invention has an actuator main body 11. As shown in Figure 1, an actuator 10 of the present invention has an actuator main body 11. Fig. As shown in Figures 2-4, the actuator main body has 11 artificial muscles 12 that are positioned parallel to each other and bundled together.

[0010] As in Fig. As shown in Figure 4, each artificial muscle 12 comprises an elastic tube 13, which has a circular cross-section and a through-opening 14 through which fluid, such as compressed air, is supplied. The elastic tube 13 is extensible and retractable in an axial direction and expandable and contractible in a radial direction. The elastic tube 13 is made of silicone resin, which is mainly composed of high-molecular-weight silicone. However, the elastic tube 13 can be made of other elastically deformable materials, such as synthetic resin and synthetic rubber. One outer surface of the elastic tube 13 is covered by a braided tube 15.The braided tube 15 is a braided structural element formed by interlacing Tetoron threads into a tubular shape and covers the outside of the elastic tube 13 to reinforce it. The material for the braided tube 15 is not limited to Tetoron, and various materials, such as polyester fibers, can be used. As shown in . Fig. As shown in Figure 4, the elastic tube 13 is partially exposed to the outside through gaps formed between the threads that configure the braided tube 15. Fig. Figure 4 shows a single layer of the braided hose 15 covering the outside of the elastic hose 13; however, multiple layers of braided hoses can be used to cover the elastic hose 13.

[0011] As in Fig. As shown in Figure 1, the actuator main body 11 has two end sections; a first cylindrical outer body 21 is attached to one end section of the actuator main body 11, and a second cylindrical outer body 22 is attached to the other end section of the actuator main body 11. The cylindrical outer bodies 21 and 22 are made of metal or resin. A connecting section 23 is provided in the first cylindrical outer body 21, and a connecting section 24 is provided in the second cylindrical outer body 22. The connecting sections 23 and 24 are made of thermosetting resin and are used to connect the elastic tube 13 to the braided tube 15, to connect the artificial muscles 12 to each other, and to connect the cylindrical outer bodies 21 and 22 to the artificial muscles 12. As shown in Figure 1, the connecting sections 23 and 24 are made of thermosetting resin and are used to connect the elastic tube 13 to the braided tube 15, to connect the artificial muscles 12 to each other, and to connect the cylindrical outer bodies 21 and 22 to the artificial muscles 12. Fig. As shown in Figure 3, before heat curing, fluid thermosetting resin, forming the connecting section 23, is injected into a gap between the first cylindrical outer body 21 and the artificial muscles 12; resin flows into the gap between the threads that configure the braided tube 15 and is heat cured, thereby connecting the elastic tube 13 to the braided tube 15. In the same way, resin, forming the connecting section 24, flows into the gap between the threads that configure the braided tube 15 and connects the elastic tube 13 to the braided tube 15.

[0012] Any number of artificial muscles 12 can be selected for the configuration of the actuator main body 11. As in Fig. As shown in Figure 2(B), the artificial muscles 12 can be positioned spaced apart from one another and bundled together, or the artificial muscles 12 can have one outer circumferential surface in contact with outer circumferential surfaces of other artificial muscles 12 and be bundled together. Even when the artificial muscles 12 are bundled together, with their outer circumferential surfaces in contact with other outer circumferential surfaces, when fluid thermosetting resin forming the connecting sections 23 and 24 is injected into the cylindrical outer bodies 21 and 22, respectively, the thermosetting resin flows into the gap in the braided tube 15 of each artificial muscle 12. When the thermosetting resin injected into the cylindrical outer bodies 21 and 22 is thermocured, the connecting sections 23 and 24 are formed, so that adjacent artificial muscles 12 are connected to one another.The depth of the connecting section 23 or 24 from its surface to an end face of the actuator 10, or a length “D” in an axial direction of the connecting section, is less than a length of the cylindrical outer body 21 or 22 in an axial direction. However, the connecting sections 23 and 24 can have the same axial lengths as the cylindrical outer bodies 21 and 22.

[0013] As mentioned above, the thermosetting resin is injected into the outer surface of both end sections of the artificial muscles 12, and this resin fixes the artificial muscles 12 to the cylindrical outer bodies 21 and 22. Because the through-hole 14 on the end face of the actuator 10 is open, no sealing elements with connecting openings need to be inserted into the elastic tube 13. Since no sealing elements need to be inserted into the elastic tube 13, the actuator main body 11 can be manufactured with a small diameter using the artificial muscles 12; thus, miniaturization of the actuator 10 can be achieved.

[0014] Fig. 5 (A) is a front view showing the actuator 10 attached to a swing arm and in an extended state; Fig. Figure 5 (B) is a front view showing the actuator 10 in a contracted state.

[0015] The oscillating arm 30 has a first oscillating element 31 and a second oscillating element 32. Both oscillating elements 31 and 32 are oscillatively connected to each other by a pin 33. A first bracket 34 is attached to the first oscillating element 31, and a second bracket 35 is attached to the second oscillating element 32. A first connecting element 41 is attached to one end section of the actuator body 11, and a second connecting element 42 is attached to the other end section of the actuator body 11. The first connecting element 41 is attached to the first bracket 34, and the second connecting element 42 is attached to the second bracket 35. In this way, one end section of the actuator body 11 is attached to the first oscillating element 31, and the other end section of the actuator body 11 is attached to the second oscillating element 32.

[0016] A supply tube 36 is attached to the first connecting element 41 and supplies fluid, such as compressed air; compressed air supplied by the supply tube 36 is further supplied to all through-openings 14 in the artificial muscles 12 that configure the actuator main body 11. In contrast, the second connecting element 42 blocks the connection between the through-openings 14 of the artificial muscles 12 and the outside by means of a locking element. As a result, the oscillating elements 31 and 32 are located as shown in Fig. Figure 5(A) shows the artificial muscles 12 in a stretched state before being swung when no fluid is supplied. When compressed air is supplied from the outside to the through-holes 14 via the supply tube 36, each artificial muscle 12 expands radially while contracting longitudinally. Thus, as shown in Fig. As shown in Figure 5 (B), the swing arm 30 is bent around the pin 33. In this way, when the actuator 10 is used to drive the swing arm 30, the swing arm 30 can be driven by supplying fluid to or draining fluid from the artificial muscles 12.

[0017] Fig. Figure 6 is a partial cross-sectional view showing the actuator with connecting elements attached to its respective end sections. As in Fig. As shown in Figure 6, the first connecting element 41 has the same structure as the second connecting element 42, and each connecting element has a cylindrical connecting main body 43. The connecting main body 43 is made of metal or solid resin. Each connecting main body 43 is provided with a large-diameter opening 44 and a small-diameter opening 45; a contact surface 46 is provided between the large-diameter opening 44 and the small-diameter opening 45 and extends radially along the connecting main body. An end section of the actuator main body 11 is inserted into the first connecting element 41, and an end face of the first cylindrical outer body 21 rests against the contact surface 46.The other end section of the actuator main body 11 is inserted into the second connecting element 42, and one end side of the second cylindrical outer body 22 rests against the contact surface 46.

[0018] A sealing element 47 is provided in each connecting main body 43 and is positioned on the same side as the contact surface 46 in the large-diameter opening 44; each sealing element 47 seals gaps between the large-diameter opening 44 and the cylindrical outer bodies 21 and 22. A guide ring 48 is provided in an opening end section of the large-diameter opening 44 and is provided with an engagement claw 49 that engages with the connecting main body 43. A locking element 51 is located between the guide ring 48 and the sealing element 47.

[0019] The locking element 51 is made of an elastic metal, such as stainless steel, and comprises the following: a cylindrical section 51a that fits into the large-diameter opening 44; and a locking claw 51b that is bent at an end section of the cylindrical section 51a on the side of the guide ring 48 and extends radially inward toward the sealing element 47. As a result, when an end section of the actuator main body 11 is inserted into the connecting main body 43, the cylindrical outer body 21 or 22 exerts pressure on a tip end of the locking claw 51b, causing the locking claw 51b to deform elastically and expand radially outward, thus permitting the insertion of the actuator main body 11.In contrast, when the actuator main body 11 is pulled away from the connecting main body 43, the locking claw 51b is pressed against the cylindrical outer body 21 or 22, and a self-tensioning effect of the locking claw 51b prevents the actuator main body 11 from falling out of the connecting main body 43.

[0020] A release ring 52 is attached to the guide ring 48 and is movable in an axial direction of the guide ring. The release ring 52 is made of metal or solid resin and has a cylindrical section 53 that is slidably fitted in the guide ring 48. One end section of the cylindrical section 53 is provided with a claw activation section 53a that abuts the locking claw 51b; the other end section of the cylindrical section 53 is provided with an active section 53b that projects radially outwards. The release ring 52 is provided with an engagement claw 53c that engages with the guide ring 48, and this engagement between the engagement claw 53c and the guide ring 48 prevents the release ring 52 from falling out of the main connecting body 43. When the release ring 52 moves towards the locking member 51 via the Fig. When the locking claw 51b is pushed outwards to the position shown in Figure 6, it is elastically deformed radially outwards and moved away from the first cylindrical outer body 21. At this point, the actuator main body 11 can be detached from the connecting main body 43 by pulling the actuator main body 11 out of the connecting main body 43. Thus, the first connecting link 41 is designed as a quick-connect mechanism 54, and the second connecting link 42 is designed as a quick-connect mechanism 55. The actuator main body 11 can then be attached to the connecting main body 43 by inserting the end section of the actuator main body 11 into the connecting main body 43. Furthermore, the actuator main body 11 can be detached from the connecting main body 43 by pressing the release ring 52.

[0021] As in Fig. As shown in Figure 6, “L” indicates a length in an axial direction of the actuator main body from the contact surface 46 to the locking claw 51b, or a length from an end face of the actuator main body 11 to a snap point where the locking element 51b snaps into the cylindrical outer body 21 or 22 of the actuator main body 11. Furthermore, “D” indicates the length of the connecting section 23 or 24 in the axial direction of the connecting section, or the length from the face of the connecting section 23 or 24 to the end face of the actuator main body 11. The length “D” in the axial direction of the connecting section is set to be greater than the length “L” in the axial direction of the actuator main body (D>L).By adjusting the depth of the connecting section 23 or 24, or the length "D" in the axial direction of the connecting section, to be greater than the length "L" at the snap point of the locking element 51, a clamping force of the locking element 51 is applied to the connecting section 23 or 24. Thus, the end section of the actuator main body 11 can be reliably attached to the connecting main body 43 without deformation, even if the cylindrical outer bodies 21 and 22 are thinner. This allows the number of artificial muscles 12 in the actuator main body 11 to be increased without the need to change the size of the cylindrical outer bodies 21 and 22.

[0022] The depth of the connecting section 23 or 24, or the length "D" in the axial direction of the connecting section, is further described below. Each connecting section 23 or 24 in the cylindrical outer body 21 or 22 has a surface facing the end face of the opposite actuator main body 11; the surfaces of the connecting sections 23 and 24 tend not to be completely perpendicular to the axial direction of the connecting section after completion. In such a case, the shortest length from the end face of the actuator main body 11 to the surface that is not completely perpendicular to the axial direction of the actuator main body is defined as the depth of the connecting section, or the length "D" in the axial direction of the connecting section. In other words, an adhesive only needs to be applied in the radial direction with respect to the snap point of the locking element 51.

[0023] The first connecting element 41, attached to one end section of the actuator body 11, is connected to the supply tube 36, which is connected to the small-diameter opening 45. Fluid supplied through the supply tube 36 from a fluid supply source 37 is also supplied to each through-opening 14 in the elastic tubes 13. The second connecting element 42, attached to the other end section of the actuator body 11, is provided with a closure element 38 that prevents fluid from flowing out of the elastic tube 13. Although the small-diameter opening 45 can be omitted in the second connecting element 42, the number of actuator 10 parts can be reduced by using the second connecting element 42, which has the same structure as the first connecting element 41.

[0024] Fig. Figure 7 is a cross-sectional view showing a variation of the first connecting element 41 attached to an end section of the actuator. The first connecting element 41 has a connecting main body 43a, and the connecting main body 43a has a central section extending radially from it, which is provided with a small-diameter opening 45. An end section of the connecting main body 43a is provided with a large-diameter opening 44, and a quick-connect mechanism 54, which has the same structure as the one shown in Figure 7, is attached to the connecting main body 43a. Fig.The connecting main body 43, shown in Figure 6, is provided in the large-diameter opening 44. The other end section of the connecting main body 43a is provided with a large-diameter opening 44a, and a quick-connect mechanism 56 is provided in the large-diameter opening 44a. The quick-connect mechanism 56 has the same structure as the quick-connect mechanism 54; links identical to those configuring the quick-connect mechanism 54 are indicated by the same reference numerals, and descriptions of the quick-connect mechanism 56 in addition to those of the quick-connect mechanism 54 are omitted accordingly. The connecting main body 43a is provided with a feed tube 36, which is detachably attached by the quick-connect mechanism 56.

[0025] The present invention is not limited to the embodiments mentioned above and can be modified in various ways, provided that the modifications do not deviate from the scope of protection of the invention as defined by the dependent claims. For example, the cross-sectional shape of the elastic hose 13 is not limited to being circular, but can instead be four-sided, polygonal, star-shaped, or the like. Furthermore, the second cylindrical outer body 22 can be omitted, and the end face of the elastic hose 13 facing the second cylindrical outer body 22 can be sealed with resin. INDUSTRIAL APPLICABILITY

[0026] The actuator of the present invention is used to drive two oscillating elements which are connected to each other by a pin.

Claims

[1] Actuator (10) comprising: an actuator main body (11) having a plurality of artificial muscles (12), each artificial muscle (12) having an elastic tube (13) and a braided tube (15) covering an outer side of the elastic tube (13); a cylindrical outer side body (21, 22) attached to an end portion of the actuator main body (11); a connecting portion (23) provided in the cylindrical outer body (21, 22), the connecting portion (23) connecting the elastic tube (13) to the braided tube (15) and connecting the cylindrical outer body (21, 22) to the artificial muscles (12); and a connecting member (41, 42) up to which the cylindrical outer body (21, 22) is inserted, wherein a locking member (51) is provided on the connecting member (41, 42) and fastens the cylindrical outer side body (21, 22) and the connecting member (41, 42) to each other, and wherein a length in an axial direction from an end side of the actuator main body (11) to a surface of the connecting portion (23) is more than a length in an axial direction from the end side of the actuator main body (11) to a snap point at which the locking member (51) snaps into the cylindrical outer side body (21, 22). [2] Actuator (10) comprising: an actuator main body (11) having a plurality of artificial muscles (12), each artificial muscle (12) having an elastic tube (13) and a braided tube (15) covering an outer side of the elastic tube (13); a first cylindrical outer side body (21) attached to an end portion of the actuator main body (11); a second cylindrical outer side body (22) attached to the other end portion of the actuator main body (11); a connecting portion (23) provided in the first cylindrical outer body (21) and the second cylindrical outer body (22), the connecting portion (23) connecting the elastic tube (13) to the braided tube (15) and connecting the first and second cylindrical outer bodies (21, 22) to the artificial muscles (12), a first connecting member (41) up to which the first cylindrical outer side body (21) is inserted; and a second connecting member (42) up to which the second cylindrical outer body (22) is inserted, wherein a locking member (51) for fastening the first cylindrical outer side body (21) and the first connecting member (41) to each other is provided on the first connecting member (41), and a locking member (51) for fastening the second cylindrical outer side body (22) and the second connecting member (42) to each other is provided on the second connecting member (42), and wherein a length in an axial direction from one end side of the actuator main body (11) to a surface of the connecting portion (23) is more than a length in the axial direction from one of the end sides of the actuator main body (11) to a snap point at which one of the locking members (51) snaps into the cylindrical outer side body (21, 22).

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