Fluid actuator

Claim 2

A fluid actuator comprising an axially elongated flexible hollow thin-walled shell defining a fluid chamber and having a pair of axially opposed end openings, said shell being movable between axially extended and retracted positions in response to variation of fluid pressure in said chamber and having a surface of substantially constant area in all of said positions, said surface in said extended position having a fluted configuration characterized by a circumaxially spaced series of axially extending ridges and valleys, said surface in said retracted position comprising substantially a surface of revolution, a pair of coupling members, each of said coupling members being associated with one of said end openings in fluid tight sealing engagement with said shell, at least one of said coupling members having a fluid passageway therethrough communicating with said chamber, and a circumaxially spaced series of elongated strands connected to said coupling members and extending in an axial direction therebetween, each of said strands being disposed in an associated one of said valleys when said shell is in said extended position.

Claim 3

A fluid actuator as set forth in claim 1 wherein each of said strands is attached to said shell along the entire length thereof intermediate said coupling members.

Claim 4

A fluid actuator as set forth in claim 1 wherein each of said coupling members includes a circumaxially spaced series of generally radially outwardly extending binding posts and each of said strands is connected to an associated one of said posts.

Claim 5

A fluid actuator as set forth in claim 1 including connecting means associated with at least one of said coupling members.

Claim 6

A fluid actuator as set forth in claim 4 wherein said connecting means comprises a threaded portion of said one coupling member.

Claim 7

A fluid actuator as set forth in claim 1 wherein said strands comprise a continuous cord.

Claim 8

A fluid actuator as set forth in claim 1 wherein said shell is made from an elastomeric material.

Claim 9

A fluid actuator as set forth in claim 1 including a plurality of other strands attached to and generally circumaxially surrounding said shell in said retracted position.

Claim 10

A fluid actuator as set forth in claim 8 wherein said other strands are axially spaced apart and comprise convolutions of a single strand.

Claim 11

A fluid actuator as set forth in claim 1 wherein each of said coupling members is received in an associated one of said end openings.

Claim 12

A fluid actuator as set forth in claim 1 wherein said shell includes a pair of generally cylindrical axially extending neck portions, each of said neck portions defining an associated one of said end openings, and each of said coupling members is received in and associated with one of said neck portions and has an annular flange thereon disposed within said shell, said flange having a diameter larger than the inside diameter of said associated neck portion.

Claim 13

A fluid actuator as set forth in claim 7 wherein said strands aRe bonded to said elastomeric material.

Claim 14

A fluid actuator as set forth in claim 1 wherein said surface in said retracted position has a generally prolate spheroidal form.

Claim 15

A fluid actuator as set forth in claim 1 including a control unit connected to one of said coupling members and having an operating member disposed within said chamber, said other coupling member including a rodlike extension projecting axially into said chamber in alignment with said operating member for moving said operating member when said shell is moved from said axially extended to said axially retracted position.

Claim 16

A fluid actuator comprising an axially elongated hollow flexible thin-walled shell made from elastomeric material defining a fluid chamber and movable between axially extended and retracted positions in response to variation of fluid pressure in said chamber and having a surface of substantially constant area in all of said positions, said shell including a body portion of prolate spheroidal form in said retracted position and characterized by a circumaxially spaced series of ridges and valleys in said extended position, said shell having generally cylindrical tubular neck portions extending axially outwardly from opposite ends of said body portion, a pair of axially elongated generally cylindrical coupling members, each of said coupling members received in an associated one of said neck portions in fluidtight sealing engagement therewith, at least one of said coupling members having a fluid passageway therethrough communicating with said chamber, each of said coupling members having a circumaxially spaced series of generally radially outwardly extending binding posts thereon, a circumaxially spaced series of axially elongated substantially nonextensible strands, each of said strands being bonded to said shell along its entire length and connected to one of said binding posts associated with each of said coupling members and extending therebetween, each of said strands being disposed in an associated one of said valleys in said extended position, and another substantially inextensible strand bonded to said shell and forming a plurality of axially spaced convolutions generally circumferentially surrounding said body portion in said contracted condition.

Claim 17

A fluid actuator comprising an axially elongated hollow flexible thin-walled shell made from elastomeric material defining a fluid chamber and movable between axially extended and retracted positions in response to variation of fluid pressure in said chamber and having a surface of substantially constant area in all of said positions, said shell including a body portion of prolate spheroidal form in said retracted position and characterized by a circumaxially spaced series of ridges and valleys in said extended position, said shell having generally cylindrical tubular neck portions extending axially outwardly from opposite ends of said body portion, a pair of axially elongated generally cylindrical coupling members, each of said coupling members received in an associated one of said neck portions in fluidtight sealing engagement therewith, at least one of said coupling members having a fluid passageway therethrough communicating with said chamber, each of said coupling members having a circumaxially spaced series of generally radially outwardly extending binding posts thereon, a circumaxially spaced series of axially elongated substantially nonextensible strands, each of said strands being bonded to said shell along its entire length and connected to one of said binding posts associated with each of said coupling members and extending therebetween, each of said strands being disposed in an associated one of said valleys in said extended position, and another substantially inextensible strand bonded to said shell and forming a plurality of axially spaced convolutions generally circumferentially surrounding said body portion in said contracted condition.