JP2010127429A - Fluid actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid actuator, capable of attaining a large contraction rate and a large stroke thereby. <P>SOLUTION: An inner member 1 extends/contracts in the radial direction of the inner member 1 according to rise/drop of pressure of fluid within a housing space 12. An outer member 2 is formed in a cylindrical shape. The inner member 1 is housed within the outer member 2. The outer member 2 is pressed to the inner member 1 when the inner member 1 is radially extended, and the outer member 2 itself is displaced outwardly in the radial direction. The axial length in the outer member 2 is reduced by the radially outward displacement of the outer member 2. At least one end of the inner member 1 in the axial direction is relatively displaceable in the axial direction relative to the outer member 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an actuator using a fluid. More specifically, the present invention relates to an actuator that obtains a driving force by converting a change in fluid pressure into a displacement.

  Fluid actuators such as air cylinders, hydraulic cylinders, and rubber artificial muscles have a feature that the output / weight ratio is larger than other types of actuators, for example, electromagnetic actuators.

  The artificial rubber muscle is an actuator that utilizes expansion / contraction by supplying and discharging pressurized fluid. This rubber artificial muscle can be significantly lighter than other fluid cylinders due to its simple structure. Further, since the artificial rubber muscle does not have a friction part like the piston of the fluid cylinder, it does not cause stick-slip. Therefore, it is considered that the artificial rubber muscle is suitable for uses such as a robot manipulator, a rehabilitation device, and an operation assisting device in addition to being used in place of the fluid cylinder.

  As the rubber artificial muscle, one using air pressure as fluid pressure is well known as a pneumatic rubber artificial muscle. The principle of the pneumatic rubber artificial muscle is to convert the expansion of the tubular elastic body into the contraction in the axial direction. Hereinafter, the prior art of pneumatic rubber artificial muscle will be described.

(Braided fiber-coated rubber artificial muscle)
As a braided fiber coating type, a McKibben type artificial muscle is well known, and its principle is disclosed in, for example, Patent Document 1 (US Pat. No. 2,844,126). This is composed of a tubular elastic body, a tubular covering body made of braided fibers covering the tubular elastic body, and a fixing member for sealing the both ends of the tubular elastic body and the covering body while fixing them.

  In this technique, when the tubular elastic body is expanded by supplying air pressure, the outer tubular covering is also expanded. Then, the expansion of the tubular covering is converted into its axial contraction by the pantograph mechanism in the braided structure of the tubular covering. And contraction force can be transmitted outside via the both ends of a tubular covering. As for the McKibben type artificial muscle, the basic operation is described in Patent Document 2 (Japanese Patent Laid-Open No. 48-24175), and the theoretical shrinkage is disclosed in Patent Documents 3 and 4 (Japanese Patent Laid-Open No. 50-52872 and Japanese Patent Publication No. 52-40378). No.) shows an example of a stitch structure of a tubular covering body, Patent Document 5 (Japanese Patent Application Laid-Open No. 2003-301807) shows an example of friction reduction between an elastic body and a covering body, and Patent Document 6 (Japanese Patent Application No. 2005-504001). Issue).

(Axial fiber reinforced rubber artificial muscle)
As an axial fiber reinforced type, a Warsaw type artificial muscle is well known. This is composed of a tubular elastic body, fibers embedded in the elastic body along the axial direction of the tubular elastic body, and a fixing member that seals both ends of the tubular elastic body including the fibers. In this technique, when air pressure is supplied to the inside of the tubular elastic body, the tubular elastic body strengthened in the axial direction expands in a spherical shape and narrows the length in the axial direction. Therefore, in this technique, the contractile force can be transmitted to the outside through the sealed ends. An example of this type of artificial rubber muscle is shown in Patent Document 7 (Japanese Patent Laid-Open No. 2001-355608).

(Cross fiber reinforced rubber artificial muscle)
A cross-fiber reinforced rubber artificial muscle is shown in Patent Document 8 (US Pat. No. 6,349,746). This rubber artificial muscle is composed of a tubular elastic body, crossed fibers embedded in the elastic body at an angle with respect to the axial direction of the tubular elastic body, and a fixing member that seals both ends of the tubular elastic body. . In this technique, when air pressure is supplied to the inside of the tubular elastic body, the tubular elastic body expands. Then, the pantograph mechanism by the cross fiber embedded in the tubular elastic body converts the expansion force into the contraction force in the axial direction. Thereby, in this technique, contractile force can be transmitted outside via the sealed both ends in a tubular elastic body.

(Theoretical shrinkage of conventional rubber artificial muscle)
The shrinkage rate calculated analytically in the above-described conventional rubber artificial muscle will be described below. Here, the contraction rate is the ratio of the length of the active contraction stroke (length L2 in FIG. 13) to the length (length L1 in FIG. 13) at the maximum extension of the artificial rubber muscle.

と算出される。 FIG. 13 (conventional example) shows an operation in a braided fiber covered type or crossed fiber reinforced rubber artificial muscle. The maximum shrinkage is based on the mechanical balance between the expansion force of the tubular elastic body and the tension of the braided fiber covering it.

Is calculated.

On the other hand, FIG. 14 (conventional example) shows an operation in an axial fiber-reinforced rubber artificial muscle. The maximum shrinkage is calculated to be about 54% from a mechanical balance between the internal pressure of the tubular elastic body and the tension of the axial fibers that reinforce the elastic body.
US Patent 2,844,126 JP-A-48-24175 JP 50-52872 A Japanese Patent Publication No.52-40378 JP 2003-301807 A Japanese Patent Application No. 2005-504001 JP 2001-355608 US Patent 6,349,746

(First issue: shrinkage)
As described above, the theoretical shrinkage of the conventional artificial rubber muscle was 42% in the braided fiber-covered type and the cross fiber-reinforced type, and 54% in the axial direction fiber-reinforced type. However, in the actually manufactured artificial rubber muscle, only a shrinkage rate lower than the theoretical value can be obtained due to loss due to elastic deformation and friction of the tubular elastic body. The shrinkage rate in actual products is considered to be about 32% at the maximum in the braided fiber-covered type and the cross fiber reinforced type, and about 41% in the axial direction fiber-reinforced type.

  Therefore, the first problem in the present invention is to realize a large contraction rate and a large stroke thereby.

(Second problem: durability)
Conventional rubber artificial muscles have a problem that it is difficult to improve durability and pressure resistance because the tubular elastic body is made of an elastic material.

In addition, as a problem known in the braided fiber-coated artificial muscle,
-With repeated expansion and contraction, the braided fiber is broken due to friction with the tubular elastic body,
・ In the state where the tubular elastic body swells, the tubular elastic body may protrude from between the spread meshes, and the load on the braided fiber may increase. ・ The friction between the tubular elastic body and the braided fiber coating may increase. There is a possibility that the tubular elastic body may be worn, and it may be costly to increase the wear resistance of the tubular elastic body.

  In cross fiber reinforced and axial fiber reinforced artificial muscles that integrate tubular elastic bodies and reinforcing fibers, the durability is improved, but the elastic strength of tubular elastic bodies is inferior to inelastic materials. Since materials are used, deterioration due to fatigue is inevitable.

  That is, the second problem in the present invention is to improve durability in repeated operations.

(Third issue: Efficiency)
Another known problem in braided fiber covered and cross fiber reinforced artificial muscles is energy loss due to friction and elastic deformation of the tubular elastic body. This causes deterioration of hysteresis characteristics and a decrease in shrinkage rate in low pressure operation.

  The third problem in the present invention is to achieve high efficiency by reducing friction and energy loss.

(Fourth issue: Pressure resistance)
In the axial fiber-reinforced artificial muscle, the reinforcing fibers are arranged only in the axial direction, so that friction between the tubular elastic body and the tubular covering during elastic operation and elastic deformation of the elastic body in the axial direction are possible. Can be suppressed. However, in the axial direction fiber-reinforced artificial muscle, there is no reinforcing fiber other than in the axial direction. For this reason, the force in the circumferential direction must be withstood by the elastic force of the film which is an elastic body. Then, this type of artificial muscle has a problem that it is difficult to increase pressure resistance. For example, the actual pressure resistance of this type is considered to be about 1/3 or less compared to braided fiber-covered and cross-fiber reinforced artificial muscles.

  That is, the fourth problem in the present invention is to improve the pressure resistance.

(Fifth issue: output and volume)
In the conventional type of artificial rubber muscle, the end of the tubular elastic body to which the internal pressure is applied is sealed and the end of the tubular elastic body and the outer tubular covering body are sealed together to attach the output end. Yes. Furthermore, in order to firmly attach the output end to the tubular covering, a relatively large and heavy mechanism such as a metal bolt-nut mechanism is used as the sealing means. For this reason, conventional rubber artificial muscles are disadvantageous in that they are large in size and tend to be heavy.

  Considering application to various devices, it is desirable that the fluid actuator has a small occupied volume and a shape that is easy to arrange. The braided fiber-covered and cross-fiber reinforced artificial muscle has a surface that is easy to place in that the outer shape at the time of maximum contraction is cylindrical, but in expansion and contraction, it causes deformation in the length direction. The shape of the occupied volume is complicated. On the other hand, the axially line-reinforced artificial muscle has a spherical outer shape at the time of maximum contraction, and its diameter can be three times that at the time of maximum extension.

  That is, the fifth problem in the present invention is to realize a space-saving shape.

  The present invention has been made to address any or all of the above-described problems depending on the embodiment.

  The present invention has a configuration described in any of the following items.

(Item 1)
It has an inner member and an outer member,
The inner member is provided with a storage space for storing fluid therein.
The inner member is configured to expand / contract at least in one direction of the inner member in accordance with the increase / decrease of the pressure of the fluid in the storage space.
The outer member is configured in a cylindrical shape,
The inner member is housed inside the outer member;
When the inner member expands in the one direction, the outer member is pressed by the inner member, and the outer member itself is displaced radially outward.
And the outer member has a configuration in which the axial length of the outer member is reduced by being displaced radially outward.
Furthermore, at least one end of the inner member in the axial direction is displaceable relative to the outer member in the axial direction.

  In the present invention, at least one end of the inner member in the axial direction can be relatively displaced in the axial direction with respect to the outer member. For this reason, on one end side of the inner member, the force to the outer member due to the expansion of the inner member acts only in the radial direction of the outer member, and does not substantially act in the axial direction.

  With this configuration, the shrinkage rate can be improved in the present invention. That is, the invention of this item corresponds to the first problem described above.

(Item 2)
The inner member includes a cylindrical portion,
The cylindrical portion is made of an inelastic material having flexibility,
Furthermore, the axial direction of the cylindrical part is substantially matched with the axial direction of the outer member,
The fluid actuator according to item 1, wherein the storage space is formed inside the cylindrical portion.

  Since the inner member in the present invention does not need to expand and contract in the axial direction, the cylindrical portion can be made of an inelastic material. However, since the inner member of the present invention needs to be capable of repeated expansion / contraction, the invention of this item employs a flexible material as the material of the cylindrical portion.

  In the invention of this item, it is possible to improve the durability and pressure resistance of the inner member by configuring the cylindrical portion of the inner member with a flexible inelastic material.

  In the invention of this item, since the cylindrical portion of the inner member is made of an inelastic material, energy loss can be suppressed to a lower level than when the inner member is made of an elastic material.

  That is, the invention of this item corresponds to the second to fourth problems.

(Item 3)
Furthermore, it has a column member,
The fluid actuator according to item 1 or 2, wherein the column member is configured to regulate the axial displacement of the inner member by supporting both ends of the inner member.

  Since the column member is used, the pressure resistance of the inner member can be improved in the invention of this item. That is, the invention of this item corresponds to the fourth problem.

(Item 4)
The fluid actuator according to any one of items 1 to 3, wherein the other end of the inner member is also displaceable relative to the outer member in the axial direction.

  Also in the invention of this item, the expansion force in the inner member can be converted into the contraction force in the outer member.

(Item 5)
The fluid actuator according to any one of items 1 to 3, wherein the other end of the inner member is fixed so as not to be relatively displaced in the axial direction with respect to the outer member.

  Also in the invention of this item, the expansion force in the inner member can be converted into the contraction force in the outer member. Also in the invention of this item, as described in item 1, since one end side of the inner member can be moved in the axial direction with respect to the outer member, a high shrinkage rate can be obtained as described above. It is.

(Item 6)
The fluid actuator according to any one of items 1 to 5, wherein the outer member has a braided structure using fibers.

  By using a braided structure, a so-called pantograph mechanism can be configured. Using this pantograph mechanism, the expansion force in the inner member can be converted into the axial contraction force in the outer member. However, it is not essential to use a braided structure.

(Item 7)
The fluid actuator according to claim 1, wherein the inner member is made of an elastic material.

(Item 8)
Furthermore, it has a wire member,
The inner member includes a cylindrical portion and a sealing tool,
The sealing tool is disposed inside at least one end of the tubular portion,
Outside the at least one end of the tubular portion, the wire member is wound in a state where tension is applied to the wire member itself,
The fluid actuator according to item 1, wherein the tubular portion and the sealing tool are fixed to each other by the tension in the wire member.

  In the invention of this item, since the cylindrical portion of the inner member is sealed using the wire member, the outer diameter at the end of the inner member is equal to or slightly larger than the outer diameter of the sealing tool. Can be suppressed. For this reason, in the invention of this item, a space-saving outer diameter shape can be realized. That is, this invention corresponds to the fifth problem described above.

(Item 9)
Furthermore, it has a wire member,
The inner member includes a cylindrical portion and a sealing tool,
The sealing tool is disposed inside the other end of the cylindrical portion,
The wire member is wound in a state where tension is applied to the wire member itself, at a position on the outside of the other end in the cylindrical portion and on the outside of the outer member,
The fluid actuator according to item 1, wherein the tubular portion, the sealing tool, and the outer member are fixed to each other on the other end side of the inner member by the tension in the wire member.

  In the invention of this item, since the inner member and the outer member are sealed together by using the wire member at the other end side of the inner member, the outer diameter of the outer member at the sealing portion is determined by the sealing tool. It can be suppressed to the same or slightly larger than the outer diameter. For this reason, in the invention of this item, a space-saving outer diameter shape can be realized. That is, this invention corresponds to the fifth problem described above.

(Item 10)
Item 10. The fluid actuator according to item 8 or 9, wherein the side surface of the wire member is formed with an uneven portion that meshes with the side surface of the adjacent wire member itself.

  By providing the concavo-convex portion, it is possible to prevent the positional deviation between the wire members that are circulated adjacent to each other, and it is possible to improve the fixing strength by the wire member.

(Item 11)
Item 11. The fluid according to any one of items 1 to 10, wherein a lubricant capable of reducing frictional resistance between the outer surface of the inner member and the inner surface of the outer member is disposed. Actuator.

  By disposing the lubricant, it is possible to reduce the frictional resistance between the inner member and the outer member, and it is possible to reduce energy loss due to friction. That is, the invention of this item corresponds to the third problem described above.

(Item 12)
The inner member includes a plurality of branch portions that bulge due to an increase in internal pressure of the storage space,
The fluid actuator according to any one of Items 1 to 11, wherein the outer member covers each of the plurality of branch portions.

  By forming a plurality of branch portions on the inner member and individually covering each branch portion with the outer member, an output end corresponding to each branch portion can be obtained in one fluid actuator. For example, according to the present invention, it is possible to obtain three or more output ends in one actuator.

(Item 13)
The fluid actuator according to any one of items 1 to 12, and a fluid pressure supply source,
The fluid pressure supply source is configured to increase the fluid pressure inside the inner member by supplying a fluid to the inside of the inner member in the fluid actuator.

  By increasing the fluid pressure inside the inner member, the contraction force in the outer member can be obtained. As a means for lowering the internal pressure of the inner member, any appropriate means such as a means for causing a fluid to flow backward by a fluid pressure supply source, a means for providing a valve on the inner member and discharging it to the outside can be used.

  ADVANTAGE OF THE INVENTION According to this invention, the fluid actuator which can implement | achieve a big contraction rate and the big stroke by it can be provided.

(First embodiment)
Hereinafter, a fluid actuator according to a first embodiment of the present invention will be described with reference to FIGS.

  The fluid actuator according to the present embodiment includes an inner member 1 and an outer member 2 as basic components.

  The inner member 1 includes a cylindrical portion 11 whose both ends are closed by appropriate sealing means. The inside of the cylindrical portion 11 is a storage space 12 in which a fluid can be stored (see FIG. 2). In this embodiment, fluid pressure can be supplied to the inside of the storage space 12 inside the cylindrical portion 11 by an appropriate fluid pressure supply source 5. The fluid supply source 5 preferably includes a hose or a tube for supplying fluid to the cylindrical portion 11. Moreover, it is preferable that the cylindrical part 11 is provided with a joint for connecting a hose or a pipe of the fluid supply source 5. This joint is preferably a mechanism that allows the hose or pipe to be attached and detached with a single touch.

  In this embodiment, the cylindrical portion 11 is made of an inelastic material having flexibility. As the inelastic material, for example, a thin film fluororesin (PTFE) is particularly suitable because it has low friction and good mechanical properties.

  Moreover, the cylindrical part 11 is formed in the cylinder shape in this embodiment, and the axial direction is made to correspond with the axial direction of the outer member 2.

  The inner member 1 is configured to expand / contract in one direction of the inner member 1 (in this example, the radial direction of the inner member) as the fluid pressure increases / decreases inside the storage space 12.

  The fluid used in this embodiment is air. However, the fluid is not limited to air but may be a liquid or a gel material. Specifically, for example, it is conceivable to use water that is easy to handle or carbon dioxide gas that can be used in a commercially available cylinder.

  The outer member 2 is configured in a cylindrical shape. The inner member 1 is accommodated in the outer member 2 (see FIG. 1).

  When the inner member 1 expands in the radial direction, the outer member 2 is pressed by the inner member 1 and the outer member 2 itself is displaced outward in the radial direction. And the outer member 2 has a configuration in which the axial length of the outer member is reduced by being displaced radially outward.

  Furthermore, one end (the left end in FIG. 1) of the inner member 1 in the axial direction is relatively displaceable in the axial direction with respect to the outer member 2. That is, one end side of the inner member 1 is in an unconstrained state with respect to the outer member 2.

  Specifically, the outer member 2 in this embodiment is configured by a braided structure using fibers. As a fiber used here, a thing with a low expansion-contraction rate is preferable from a viewpoint of raising a shrinkage rate. By using the braided structure, expansion in the radial direction can be converted into contraction force by a so-called pantograph action. However, it is not essential to use a braided structure. For example, a material that has flexibility and does not expand and contract in the axial direction can be used as the outer member 2.

  In the present embodiment, the other end (the right end in FIG. 1) of the inner member 1 is fixed to the outer member 2 by an appropriate fixing tool. In addition, the fixing member seals the end portion of the inner member 1 and can receive the fluid from the fluid pressure supply source 5.

(Operation of the first embodiment)
Next, the operation of the fluid actuator according to the present embodiment will be described with reference to FIG. First, in the initial state (see FIG. 3A), the inside of the cylindrical portion 11 of the inner member 1 is in a reduced pressure state (for example, 1 atm or less).

  Next, the fluid pressure is supplied into the cylindrical portion 11 by the fluid pressure supply source 5 (see FIG. 1). Then, the cylindrical part 11 expand | swells to radial direction outer side, and pushes the outer member 2 to the radial direction outer side (refer FIG.3 (b)).

  Then, the entire length of the outer member 2 contracts. Thus, in the fluid actuator of this embodiment, fluid pressure can be converted into contraction force. Therefore, for example, by using the end portion 22 (see FIG. 3) of the outer member as the output end, the contraction force can be taken out and used as a power source of an appropriate device, for example, a robot.

  Moreover, the shape of the cylindrical part 11 returns to an initial state by returning the pressure in the cylindrical part 11 to an initial state. Thereafter, by supplying the fluid pressure to the cylindrical portion 11 again, the same operation as described above is possible. Therefore, this fluid actuator can perform a periodic contraction operation.

(Improved shrinkage)
In the present embodiment, one end of the inner member 1 can be displaced relative to the outer member 2 in the axial direction. For this reason, on one end side of the inner member 1, the pressing force to the outer member 2 due to the expansion of the inner member 1 acts only in the radial direction of the outer member 2 and does not substantially act in the axial direction.

  That is, in this embodiment, even if the inner member 1 is deformed in the radial direction, an axial force is not applied to the outer member 2. For this reason, in this embodiment, mechanical interference in the axial direction that occurs between the inner member 1 and the outer member 2 can be avoided. As a result, it is considered that the shrinkage rate in this embodiment can theoretically approach 100%.

  On the other hand, in the prior art, the end portions of the tubular elastic body and the tubular covering body are fixed to each other, or the tubular elastic body extends without gaps inside the tubular covering body. Therefore, in the conventional technique, the balance of the axial force between the tubular elastic body and the tubular covering has limited the shrinkage rate.

  In addition, it is preferable that the axial direction length of the inner member 1 in this embodiment does not exceed the axial direction length of the outer member 2 at any time during operation. This is because when the length of the inner member 1 exceeds the length of the outer member 2, mechanical interference occurs and the shrinkage rate may be deteriorated.

(High efficiency and improved durability)
Furthermore, in the present embodiment, since a flexible non-elastic material is used as the cylindrical portion 11 of the inner member 1, durability and pressure resistance are compared with the case where an elastic material is used as the cylindrical portion. There is an advantage that it is possible to improve.

  Further, when both ends of the inner member are fixed to the outer member as in the prior art, the cylindrical portion also needs to expand and contract in accordance with the expansion and contraction of the outer member. Is difficult to use. In contrast, in the present embodiment, as described above, since one end of the inner member 1 is movable with respect to the outer member 2, the inner member 1 does not need to expand and contract in the axial direction. For this reason, in this embodiment, the cylindrical part 11 of the inner member 1 can be configured using an inelastic material that hardly expands and contracts in the axial direction but substantially expands and contracts only in the radial direction. Furthermore, in this embodiment, since the deformation of the cylindrical portion 11 can be limited to the radial direction, it is possible to reduce the deformation energy compared to the case where the cylindrical portion 11 is also deformed in the axial direction. become. Further, when the cylindrical portion 11 is also deformed in the axial direction, friction between the cylindrical portion 11 and the outer member 2 is generated, but in this embodiment, there is an advantage that such friction can be reduced. is there.

  Further, when an elastic body is used as the inner member, the inner member may protrude from between the meshes of the outer member in a state where the inner member bulges. On the other hand, in this embodiment, since an inelastic material is used as the inner member, the load on the outer member using the braided fiber can be reduced.

  Further, in this embodiment, the length of the inner member 1 at the time of expansion does not substantially change, and only the thickness changes. Therefore, if a cylindrical space is secured, the operation is possible. There are also advantages above.

  In the present embodiment, it is possible to arrange a lubricant for reducing the frictional resistance between the outer surface of the inner member 1 and the inner surface of the outer member 2. An example of a suitable lubricant is silicone oil, which has stable properties and can have various properties. By selecting a lubricant having various physical properties (for example, silicone oil), it is possible not only to reduce friction but also to add a functional viscosity that suppresses vibrational motion.

(Second Embodiment)
Next, a fluid actuator according to a second embodiment of the present invention will be described with reference to FIGS. 4 and 5. In the description of this embodiment, the same reference numerals are used for elements common to the fluid actuator described in the first embodiment, thereby avoiding repeated description.

  In the second embodiment, an elastic material is used as the material of the cylindrical portion 11 of the inner member 1 instead of the inelastic material. As the elastic material, for example, flexible natural rubber, silicone rubber resistant to temperature change, and polyurethane excellent in mechanical strength are considered suitable.

  The cylindrical part 11 in this embodiment is circular in cross section, and is formed in a columnar shape with both ends closed (see FIG. 5). Also in this embodiment, the fluid pressure inside the cylindrical portion 11 can be increased or decreased by the fluid pressure supply source 5.

  Also in the fluid actuator of the second embodiment, the radial expansion in the inner member 1 can be converted into the axial displacement (contraction) in the outer member 2.

  In addition, when the cylindrical part 11 of the inner member 1 is comprised with an elastic material, durability, pressure | voltage resistance, or energy efficiency may fall compared with the case where an inelastic material is used. For this reason, when the cylindrical part 11 is comprised using an elastic material, the material corresponding to requirements, such as required durability, is selected.

  However, even if an elastic material is used as the cylindrical portion 11, if it is configured to restrict axial deformation in the cylindrical portion 11, it is functionally close to that when an inelastic material is used. Is possible. As a method of restricting axial deformation, for example, an axially extended fiber is arranged inside or on the surface of the elastic material, and the axial displacement of the elastic material is restricted using the tension of the fiber. Can be considered.

  Other configurations and advantages other than those described above are the same as those of the first embodiment described above, and thus further detailed description of the second embodiment is omitted.

(Third embodiment)
Next, a fluid actuator according to a third embodiment of the present invention will be described with reference to FIG. In the description of this embodiment, the same reference numerals are used for elements common to the fluid actuator described in the first embodiment, thereby avoiding repeated description.

  In the third embodiment, as in the second embodiment, an elastic material is used as the material of the cylindrical portion 11 of the inner member 1 instead of the inelastic material.

  Moreover, the cylindrical part 11 in this embodiment is also formed in the column shape which is circular in cross section and the both ends were closed like the second embodiment. However, in the third embodiment, unlike the second embodiment, the other end side (right end side in FIG. 6) of the cylindrical portion 11 is also connected to the outer member 2 in the same manner as one end side (left end side in FIG. 6). On the other hand, relative movement in the axial direction is possible. Specifically, in this embodiment, the other end side of the cylindrical portion 11 is not restrained with respect to the outer member 2.

  Also in this embodiment, the fluid pressure inside the cylindrical portion 11 can be increased or decreased by the fluid pressure supply source 5.

  Also in the fluid actuator of the third embodiment, the radial expansion in the inner member 1 can be converted into the axial displacement (contraction) in the outer member 2.

  Other configurations and advantages other than those described above are the same as those of the second embodiment described above, and thus further detailed description of the third embodiment is omitted.

(Fourth embodiment)
Next, a fluid actuator according to a fourth embodiment of the present invention will be described with reference to FIG. In the description of this embodiment, the same reference numerals are used for elements common to the fluid actuator described in the first embodiment, thereby avoiding repeated description.

  The fluid actuator according to the fourth embodiment includes a column member 3 (see FIG. 7). The column member 3 is configured to restrict axial displacement of the inner member 1 by supporting both ends of the cylindrical portion 11 of the inner member 1. More specifically, both ends of the cylindrical portion 11 are fixed to both ends of the column member 3 and are sealed by both ends of the column member 3.

  Furthermore, the other end side (right end side in FIG. 7) of the cylindrical portion 11 in the fourth embodiment is movable in the axial direction with respect to the outer member 2 as in the case of the third embodiment. .

  In this embodiment, even when the axial force is applied to the inner member 1 from the outside, the column member 3 can prevent the axial deformation. For this reason, in this embodiment, there exists an advantage that the pressure | voltage resistance in the inner member 1 can further be improved.

  In the configuration of the first embodiment, when the inner pressure of the inner member 1 increases, the outer member 2 restrains the radial expansion. However, when the inner pressure of the inner member 1 becomes excessive or the inner member 1 weakens with time, the inner member 1 may extend in the axial direction due to an increase in the inner pressure. On the other hand, in the fourth embodiment, the pillar member 3 can prevent the inner member 1 from being deformed in the axial direction.

  Other configurations and advantages other than those described above are the same as those of the first embodiment described above, and thus further detailed description of the fourth embodiment is omitted.

(Fifth embodiment)
Next, a fluid actuator according to a fifth embodiment of the present invention will be described with reference to FIGS. In the description of this embodiment, the same reference numerals are used for elements common to the fluid actuator described in the first embodiment, thereby avoiding repeated description.

  In the fifth embodiment, the sealing tool 13 and the wire member 4 are used as members for sealing both ends of the cylindrical portion 11 of the inner member 1.

  The sealing tool 13 is arrange | positioned at the both ends of the cylindrical part 11, respectively. Since these sealing tools are similarly configured, one sealing tool will be mainly described in the following description.

  The sealing tool 13 is formed in a substantially cylindrical shape, and a groove 13a extending in the circumferential direction is formed on a side surface thereof. (See FIG. 8).

  The wire member 4 is circulated in a tensioned state from the outside of the tubular portion 11 at a position corresponding to the groove 13 a of the sealing tool 13. Thereby, in this embodiment, the cylindrical part 11 and the sealing tool 13 are mutually fixed by the tension | tensile_strength in the wire member 4. FIG. And by this structure, it can prevent that a fluid leaks from the storage space 12 of the cylindrical part 11 outside.

  An example of a method for fixing the wire member 4 to the cylindrical portion 11 will be described with reference to FIG. First, the wire member 4 is wound around the cylindrical portion 11. In the example shown in the drawing, the wire member 4 is circulated for two rounds. Next, the end portions of the wire member 4 are aligned and twisted strongly (see FIG. 9). Thereby, strong tension can be given to wire member 4. Thereafter, as shown in FIG. 8, the twisted portion is laid down sideways.

  In this embodiment, since the cylindrical part 11 of the inner member 1 is sealed using the wire member 4, the outer diameter at the end of the inner member 1 is equal to the outer diameter of the sealing tool 13, or It can be suppressed to a slightly larger extent. For this reason, according to the fluid actuator of this embodiment, it is possible to realize a space-saving outer diameter shape.

  In this embodiment, since the groove 13a is further provided in the sealing tool 13, the outer diameter shape of the fluid actuator can be further reduced.

  In addition, in this 5th Embodiment, the wire member 4 is made to circulate from the outer periphery of the cylindrical part 11 of the inner member 1. FIG. However, on the other end side of the inner member, the wire member 4 can be caused to circulate around the sealing tool 13 with the tubular portion 11 sandwiched from the outer periphery of the outer member 2. If it does in this way, not only can cylindrical part 11 be sealed, but the other end of inner member 1 and outer member 2 can be fixed. Therefore, the size of the fluid actuator can be further reduced. Even in this case, as described above, the shrinkage rate can be improved by making the one end side of the inner member 1 movable relative to the outer member 2.

  Other configurations and advantages other than those described above are the same as those of the first embodiment described above, and thus further detailed description of the fifth embodiment is omitted.

(Sixth embodiment)
Next, a fluid actuator according to a sixth embodiment of the present invention will be described with reference to FIGS. 10 and 11. In the description of this embodiment, the same reference numerals are used for the elements common to the fluid actuator described in the fifth embodiment, thereby avoiding repeated description.

  In this 6th Embodiment, the uneven part 41 which meshes with the side surface of the adjacent wire member 4 itself is formed in the side surface of the wire member 4.

  In this embodiment, by providing the concavo-convex portion 41, there is an advantage that the positional deviation between the wire members 4 that are circulated adjacent to each other can be prevented, and the fixing strength by the wire members 4 can be improved.

  Moreover, in this embodiment, since the uneven | corrugated | grooved part 41 was provided, even if it removes the part which twisted the wire member 4, the tension | tensile_strength in the wire member 4 can be hold | maintained. For this reason, in this embodiment, the outer diameter of the actuator can be made more compact.

(Seventh embodiment)
Next, a fluid actuator according to a seventh embodiment of the present invention will be described with reference to FIG. In the description of this embodiment, the same reference numerals are used for elements common to the fluid actuator described in the first embodiment, thereby avoiding repeated description.

  The inner member 1 in the present embodiment includes two branch portions 111 and 112. These branch portions 111 and 112 are configured to bulge as the internal pressure of the storage space 12 increases. More specifically, the storage space 12 is continuously formed in the branch portions 111 and 112, and the internal pressure is increased by the fluid supplied from the fluid pressure supply source 5.

  The outer member 2 is branched corresponding to the two branch portions 111 and 112, and covers the branch portions 111 and 112, respectively (see FIG. 12).

  In the present embodiment, the branch portions 111 and 112 are formed in the inner member 1 and each branch portion is individually covered with the outer member 2, so that an output corresponding to each branch portion in one fluid actuator. You can get an edge. For example, in this embodiment, the first output end 221 and the second output end 222 can be formed on the left side in FIG. If the right end in FIG. 12 is also regarded as the output end, in this embodiment, three output ends can be obtained in one actuator. Therefore, in the actuator of this embodiment, a configuration simulating the biceps brachii can be used.

  The number of branch portions may be three or more. When the number of branch portions is increased, an output end corresponding to the number of branch portions can be obtained by covering each branch portion with an outer member.

  Other configurations and advantages other than those described above are the same as those of the fifth embodiment described above, and thus further detailed description of the sixth embodiment is omitted.

  A drive device using fluid pressure can be configured by the fluid actuator of each of the embodiments described above and the fluid pressure supply source 5.

  Note that the description of the embodiment and the examples is merely an example, and does not indicate a configuration essential to the present invention. The configuration of each part is not limited to the above as long as the gist of the present invention can be achieved.

It is explanatory drawing which fractured | ruptured partially which shows the fluid actuator which concerns on 1st Embodiment of this invention. It is a cross-sectional view of the inner member in FIG. It is explanatory drawing for demonstrating operation | movement of the fluid actuator shown by FIG. The figure (a) shows the contraction state of a cylindrical part. The figure (b) shows the expansion state of a cylindrical part. It is explanatory drawing which fractured | ruptured partially which shows the fluid actuator which concerns on 2nd Embodiment of this invention. It is a cross-sectional view of the inner member in FIG. It is explanatory drawing which fractured | ruptured partially which shows the fluid actuator which concerns on 3rd Embodiment of this invention. It is explanatory drawing which fractured | ruptured partially which shows the fluid actuator which concerns on 4th Embodiment of this invention. It is explanatory drawing which fractured | ruptured partially which shows the fluid actuator which concerns on 5th Embodiment of this invention. It is explanatory drawing for demonstrating the production direction about the fluid actuator of FIG. It is explanatory drawing which fractured | ruptured partially which shows the fluid actuator which concerns on 6th Embodiment of this invention. It is explanatory drawing for demonstrating the production direction about the fluid actuator of FIG. It is explanatory drawing which fractured | ruptured partially which shows the fluid actuator which concerns on 7th Embodiment of this invention. It is explanatory drawing which shows an example of the conventional artificial muscle. It is explanatory drawing which shows an example of the conventional artificial muscle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner member 11 Cylindrical part 111 * 112 Branch part 12 Storage space 13 Sealing tool 13a Groove of sealing tool 2 Outer member 21 Fixing tool 22 Output end 221 1st output end 222 2nd output end 3 Column member 4 Wire member 41 Concavity and convexity 5 Fluid pressure supply source

Claims (13)

It has an inner member and an outer member,
The inner member is provided with a storage space for storing fluid therein.
The inner member is configured to expand / contract at least in one direction of the inner member in accordance with the increase / decrease of the pressure of the fluid in the storage space.
The outer member is configured in a cylindrical shape,
The inner member is housed inside the outer member;
When the inner member expands in the one direction, the outer member is pressed by the inner member, and the outer member itself is displaced radially outward.
And the outer member has a configuration in which the axial length of the outer member is reduced by being displaced radially outward.
Furthermore, at least one end of the inner member in the axial direction is displaceable relative to the outer member in the axial direction. The inner member includes a cylindrical portion,
The cylindrical portion is made of an inelastic material having flexibility,
Furthermore, the axial direction of the cylindrical part is substantially matched with the axial direction of the outer member,
The fluid actuator according to claim 1, wherein the storage space is formed inside the cylindrical portion. Furthermore, it has a column member,
The fluid actuator according to claim 1, wherein the column member is configured to regulate displacement in the axial direction of the inner member by supporting both ends of the inner member. The fluid actuator according to any one of claims 1 to 3, wherein the other end of the inner member is also relatively displaceable in the axial direction with respect to the outer member. The fluid actuator according to claim 1, wherein the other end of the inner member is fixed so as not to be relatively displaced in the axial direction with respect to the outer member. The fluid actuator according to claim 1, wherein the outer member has a braided structure using fibers. The fluid actuator according to claim 1, wherein the inner member is made of an elastic material. Furthermore, it has a wire member,
The inner member includes a cylindrical portion and a sealing tool,
The sealing tool is disposed inside at least one end of the tubular portion,
Outside the at least one end of the tubular portion, the wire member is wound in a state where tension is applied to the wire member itself,
The fluid actuator according to claim 1, wherein the cylindrical portion and the sealing tool are fixed to each other by the tension in the wire member. Furthermore, it has a wire member,
The inner member includes a cylindrical portion and a sealing tool,
The sealing tool is disposed inside the other end of the cylindrical portion,
The wire member is wound in a state where tension is applied to the wire member itself, at a position on the outside of the other end in the cylindrical portion and on the outside of the outer member,
The fluid actuator according to claim 1, wherein the tubular portion, the sealing tool, and the outer member are fixed to each other on the other end side of the inner member by the tension in the wire member. The fluid actuator according to claim 8, wherein an uneven portion that meshes with a side surface of the adjacent wire member itself is formed on a side surface of the wire member. The lubricant which can reduce the frictional resistance between both is arrange | positioned between the outer surface of the said inner member, and the inner surface of the said outer member. Fluid actuator. The inner member includes a plurality of branch portions that bulge due to an increase in internal pressure of the storage space,
The fluid actuator according to any one of claims 1 to 11, wherein the outer member covers each of the plurality of branch portions. A fluid actuator according to any one of claims 1 to 12, and a fluid pressure supply source,
The fluid pressure supply source is configured to increase the fluid pressure inside the inner member by supplying a fluid to the inside of the inner member in the fluid actuator.

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