US 4,375,181 AGranted

Hydraulic cylinder extending in three force modes

OwnerJohn P. Conwayinventor

Life of this patent

Estimating the term…

Loading patent…

Abstract

A multiple mode hydraulic piston assembly employing a regenerative hydraulic circuit which when incorporated in the piston of a hydraulic cylinder and assembled with a pressureized hydraulic source through appropriate piping and valving, will sequentially permit, restrict, and block liquid flow through the piston and will thus extend its piston rod in multiple force modes, namely a low force rapid extension mode, a moderate force rapid extension mode, and a high force extension mode. In response to fluid pressures within the cylinder chamber the multiple mode piston assembly automatically changes operational modes. First bi-directional flow is provided between opposing chambers, then uni-directional flow is provided from the rod end to the back end chamber, and finally flow between the chambers is blocked. A modified embodiment provides a free motion mode wherein a modest external force can displace the piston in either direction. An additional embodiment provides an arrangement of the elements offset from the geometrical axis of the piston. An embodiment of the foregoing construction provides a double-ended piston rod configuration.

Claims18

Dependent claims

In combination with a liquid fluid piston device having a pressure sealed housing, a slidable piston therein having two opposed faces of differential areas and dividing said cylinder housing into two opposing pressure chambers of variable volume, a piston rod extending from said piston passing through one of said chambers and extending from said housing, said chamber being the rod end chamber, a source of pressurized fluid, conduit means for permitting flow of pressurized fluid into and out of each of said pressure chambers, first valve means for selectively conducting fluid to the other of said opposing chambers to effect displacement of said piston, said other chamber being the back end chamber;

automatic means for varying the extension force modes of said device in response to changes in pressure conditions within said chambers, comprising
first passage means in said piston for conducting free flow of fluid through said piston between said opposing chambers,
second valve means having a stationary valve seat and independently movable discrete unattached elements actuated by changes in fluid pressures within said chambers in response to increased loads and movable in response to changes in pressures through a plurality of positions thereby providing sequentially low force rapid extension mode of movement, moderate force rapid extension mode of movement, and high force relatively slow extension mode of movement,
second passage means fluidly connecting a reference pressure to said second valve means independent of pressures within said chambers,
bias spring means for holding said second valve means in an open position until overcome by the fluid pressure in a chamber when the resisting load exceeds a predetermined value thereby allowing said second valve means to restrict flow between said chambers to uni-directional flow from the rod end chamber to the back end chamber and thereafter blocking flow between said chambers when pressure is unloaded from the rod end chamber,
relatively lighter means continually urging said valve means to a seated position, and
third valve means connected to said rod end chamber for unloading pressurized fluid from said chamber to provide said high force mode.

4 more elements

automatic means for varying the extension force modes of said device in response to changes in pressure conditions within said chambers, comprising
first passage means in said piston for conducting free flow of fluid through said piston between said opposing chambers,
second valve means in said back end chamber having a stationary valve seat and independently movable discrete unattached elements actuated by changes in fluid pressures within said back end chamber in response to increased loads and movable in response to changes in pressure through a plurality of positions thereby providing sequentially low force rapid extension mode of movement, moderate force rapid extension mode of movement, and high force relatively slow extension mode of movement,
second passage means fluidly connecting a reference pressure to said second valve means independent of pressures within said chambers,
bias spring means for holding said second valve means in an open position until overcome by the fluid pressure in a chamber when the resisting load exceeds a predetermined value thereby allowing said second valve means to restrict flow between said chambers to uni-directional flow from the rod end chamber to the back end chamber and thereafter blocking flow between said chambers when pressure is unloaded from the rod end chamber,
relatively lighter means continually urging said valve means to a seated position.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 06/226,550Filed 21 Jan 1981
Granted: 1 Mar 1983
Term ends: Not estimatedThe source records don’t support an estimate.

Classification13 codes

F15B 15/204
Other details , e.g. assembly with regulating devices: control means for piston speed or actuating force without external control, e.g. control…
F15B 11/024
Systems essentially incorporating special features for controlling the speed or the actuating force of an output member: by means of differential…
F15B 2011/0243
By means of differential connection of the servomotor lines, e.g. regenerative circuits: the regenerative circuit being activated or deactivated…
F15B 2011/0246
By means of differential connection of the servomotor lines, e.g. regenerative circuits: with variable regeneration flow