Actuator

Claim 2

A fluid operated piston-type actuator comprising: an operating cylinder defining an operating chamber having a longitudinal axis; a reciprocable piston disposed in said chamber such that a clearance is defined between said piston and said cylinder: said piston being movable in response to fluid pressure acting thereon; compressible biasing means disposed between said piston and said cylinder spacing said piston away from said cylinder: an operating shaft connected to said piston extending outwardly of said chamber through said operating cylinder; means for decelerating said piston in at least one direction of travel including a deceleration chamber defined by said piston and cylinder trapping a quantity of fluid and a restricted orifice flow path defined by said piston and cylinder communicating between said deceleration chamber and a source of low fluid pressure; and said piston being responsive to the flow of fluid through said restrictive orifice flow path to shift transverse to said axis thereby compressing said biasing means to further restrict the flow of fluid through said restricted orifice.

Claim 3

A fluid operated piston-type actuator as claimed in claim 1 wherein: said piston includes an outer peripheral surface; and said means defining said restricted orifice flow path includes a circumferential groove extending about said outer peripheral surface which groove communicates with said source of low fluid pressure.

Claim 4

A fluid operated piston-type actuator as claimed in claim 2 wherein: said operating cylinder includes an inner cylindrical surface; said outer peripheral surface of said piston is disposed in closely spaced sliding relation to said inner cylindrical surface; said circumferential groove of said piston; and said inner cylindrical surface of said cylinder define said restricted orifice flow path.

Claim 5

A fluid operated piston-type actuator as claimed in claim 3 wherein: said cylinder includes an end wall and said pump includes a fluid communication conduit extending through said inner cylindrical surface adjacent said end wall in spaced relation thereto; movement of said piston toward said end wall causing said outer peripheral surface of said piston to close said fluid communication conduit; said piston, said end wall and said inner cylindrical surface of said cylinder thereby defining said deceleration chamber; and said restricted orifice flow path defined by said circumferential groove in said piston and said inner cylindrical surface providing communication between said deceleration chamber and said fluid communication conduit.

Claim 6

A fluid operated piston-type actuator as claimed in claim 3 wherein: said cylinder includes means defining an aperture through which said operating shaft extends; said shaft and said aperture being sized to provide clearance therebetween; said outer peripheral surface of said piston and said inner cylindrical surface of said cylinder being sized to provide clearance therebetween; and said clearance between said shaft and aperture being greater than said clearance between said outer peripheral surface of said piston and said inner cylindrical surface of said cylinder.

Claim 7

A fluid operated piston-type actuator as claimed in claim 4 wherein: said cylinder includes means defining an aperture through which said operating shaft extends; said shaft and said aperture being sized to provide clearance therebetween; and said clearance between said shaft and said aperture of said cylinder being greater than said clearance between said outer peripheral surface of said cylinder.

Claim 8

A fluid operated piston-type actuator comprising: an operAting cylinder defining an operating chamber having an inner generally cylindrical surface and a pair of end walls, one of which includes an aperture; said operating chamber having a longitudinal axis; a reciprocable piston disposed within said chamber dividing said chamber into separate portions and including an outer peripheral surface disposed in closely spaced sliding relation to said inner generally cylindrical surface; compressible biasing means disposed between said piston and said cylinder; said biasing means spacing said piston away from said cylinder; an operating shaft secured to said piston and extending outwardly of said chamber through said aperture in said one end wall, said shaft being extensible and retractable in response to movement of said piston; a pair of fluid communication conduits: said conduits communicating with said chamber on opposite sides of said piston and being adapted to be placed in communication, alternately, with a source of high fluid pressure and a low fluid pressure to effect movement of said piston; at least one of said fluid communication conduits extending through said inner cylindrical surface adjacent one of said end walls in spaced relation thereto, and deceleration means for decelerating said piston upon reaching the terminal portion of its stroke in at least one direction including a deceleration chamber defined by said piston; said inner cylindrical surface and said end wall associated with said fluid communication conduit extending through said inner cylindrical surface when said piston moves to a position to cause said outer peripheral surface to close said fluid communication conduit thereby trapping a quantity of fluid in said deceleration chamber; a restricted orifice flow path defined by said piston and said cylinder communicating between said deceleration chamber and said fluid communication conduit; and said piston being responsive to the flow of fluid through said restricted orifice flow path to shift transverse to said longitudinal axis to further restrict the flow of fluid through said restricted orifice.

Claim 9

A fluid operated piston-type actuator comprising: an operAting cylinder defining an operating chamber having an inner generally cylindrical surface and a pair of end walls, one of which includes an aperture; said operating chamber having a longitudinal axis; a reciprocable piston disposed within said chamber dividing said chamber into separate portions and including an outer peripheral surface disposed in closely spaced sliding relation to said inner generally cylindrical surface; compressible biasing means disposed between said piston and said cylinder; said biasing means spacing said piston away from said cylinder; an operating shaft secured to said piston and extending outwardly of said chamber through said aperture in said one end wall, said shaft being extensible and retractable in response to movement of said piston; a pair of fluid communication conduits: said conduits communicating with said chamber on opposite sides of said piston and being adapted to be placed in communication, alternately, with a source of high fluid pressure and a low fluid pressure to effect movement of said piston; at least one of said fluid communication conduits extending through said inner cylindrical surface adjacent one of said end walls in spaced relation thereto, and deceleration means for decelerating said piston upon reaching the terminal portion of its stroke in at least one direction including a deceleration chamber defined by said piston; said inner cylindrical surface and said end wall associated with said fluid communication conduit extending through said inner cylindrical surface when said piston moves to a position to cause said outer peripheral surface to close said fluid communication conduit thereby trapping a quantity of fluid in said deceleration chamber; a restricted orifice flow path defined by said piston and said cylinder communicating between said deceleration chamber and said fluid communication conduit; and said piston being responsive to the flow of fluid through said restricted orifice flow path to shift transverse to said longitudinal axis to further restrict the flow of fluid through said restricted orifice.

Claim 10

A fluid operated piston-type actuator as claimed in claim 7 wherein said restricted flow path is defined by means including a circumferential groove formed about said outer peripheral surface of said piston.

Claim 11

A fluid operated piston-type actuator as claimed in claim 8 wherein said aperture in said end wall and said operating shaft are sized to provide clearance therebetween, and said outer peripheral surface of said piston and said inner cylindrical surface of said cylindrical surface are sized to provide clearance therebetween, said clearance between said aperture and said shaft being greater than said clearance between said peripheral surface of said piston and said inner cylindrical surface of said cylinder.

Claim 12

A fluid operated piston-type actuator as claimed in claim 1 wherein said operating cylinder includes an inner cylindrical surface, an end wall, and a fluid communication conduit extending through said inner cylindrical surface adjacent said end wall in spaced relation thereto, said cylinder further including a groove formed at said inner cylindrical surface communicating with said fluid communication conduit and extending in a direction toward said end wall, said groove cooperating with said piston to define said restricted orifice flow path.

Claim 13

A fluid operated piston-type actuator as claimed in claim 10 wherein said piston includes an outer peripheral surface disposed in closely spaced sliding relation to said inner cylindrical surface of said cylinder, said outer peripheral surface cooperating with said groove to define said restricted orifice flow path.

Claim 14

A fluid operated piston-type actuator as claimed in claim 11 wherein said groove formed at said inner cylindrical surface decreases in depth with respect to said inner cylindrical surface in a direction toward said end wall.

Claim 15

A fluid operated piston-type actuator as claimEd in claim 11 wherein said operating shaft, cylinder and piston are arranged to allow said piston outer peripheral surface to contact said inner cylindrical surface of said cylinder at said fluid communication conduit.