Double-acting hydraulic piston-and-cylinder device
First Claim
1. A double-acting piston-and-cylinder hydraulic unit which comprises:
- means for forming a cylinder;
a piston axially shiftable in said cylinder and defining therein respective hydraulic-fluid-containing chambers on opposite sides of said piston;
a piston rod connected to said piston and extending axially out of said cylinder;
an elastically deformable boot surrounding said cylinder and said rod while forming therewith a hydraulic-fluid-pressurized variable-volume compartment, said boot having a generally cylindrical segment sealingly connected to said cylinder, an outwardly widening segment diverging from and sealingly connected to said rod, and a transition segment connecting said widening segment to said generally cylindrical segment,said transition segment having, in an extended position of said piston rod, an outwardly convex shape and having a greater diameter than that of said generally cylindrical segment,a ratio between the radius (R) of said transition segment at said greater diameter than said generally cylindrical segment and an axial distance (L) between a plane of said transition segment at its greatest diameter and a location closest to said cylinder at which said boot is sealingly connected to said rod being given by the relation;
space="preserve" listing-type="equation">3;
1 ≧
R/L ≧
1;
2; and
means for fluid communication between each of said chambers and said variable-volume compartment.
1 Assignment
0 Petitions
Accused Products
Abstract
A double-acting hydraulic piston-and-cylinder unit adapted to constitute a damper for movements in a human joint prosthesis has a boot sealingly connected to the cylinder and the piston rod to receive the hydraulic fluid under pressure as the hydraulic fluid is displaced from one or the other of two cylinder chambers upon displacement of the piston rod. The boot has a conically widening region or segment sealingly secured to the rod and adjoining the cylindrical segment of the boot surrounding the cylinder in a transition segment formed as an outwardly convex bulge and designed to ensure that initial inward movement of the piston rod will give rise to a plate membrane deformation of the elastic boot while only further displacement will result in a rolling action of the membrane. This ensures a generally cylindrical uniform configuration of the boot in all positions of the rod as is essential for effective use in a prosthesis.
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Citations
5 Claims
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1. A double-acting piston-and-cylinder hydraulic unit which comprises:
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means for forming a cylinder; a piston axially shiftable in said cylinder and defining therein respective hydraulic-fluid-containing chambers on opposite sides of said piston; a piston rod connected to said piston and extending axially out of said cylinder; an elastically deformable boot surrounding said cylinder and said rod while forming therewith a hydraulic-fluid-pressurized variable-volume compartment, said boot having a generally cylindrical segment sealingly connected to said cylinder, an outwardly widening segment diverging from and sealingly connected to said rod, and a transition segment connecting said widening segment to said generally cylindrical segment, said transition segment having, in an extended position of said piston rod, an outwardly convex shape and having a greater diameter than that of said generally cylindrical segment, a ratio between the radius (R) of said transition segment at said greater diameter than said generally cylindrical segment and an axial distance (L) between a plane of said transition segment at its greatest diameter and a location closest to said cylinder at which said boot is sealingly connected to said rod being given by the relation;
space="preserve" listing-type="equation">3;
1 ≧
R/L ≧
1;
2; andmeans for fluid communication between each of said chambers and said variable-volume compartment. - View Dependent Claims (2, 3, 4, 5)
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Specification