US 6,386,508 B1Granted

Actuator having dual piston surfaces

AssigneeD-M-E Company

InventorsFred Steil, Lawrence J. Navarre, Douglas Hugo

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Abstract

A pressurized-fluid-operated actuator has two piston surfaces for providing increased output force. The actuator includes a hollow piston that is divided into two inner chambers by a stationary inner dividing wall that is rigidly connected with a cylinder end wall. The piston has an outer diameter that is smaller than the inner diameter of the cylinder, and the piston carries three axially spaced sealing rings that define two axially-spaced annular chambers between the piston and the cylinder. Each of the annular chambers is in fluid communication with a respective port provided in the cylinder wall. Introduction of pressurized fluid into one port causes the fluid pressure to act on a single piston surface to retract the piston and rod, and introduction of pressurized fluid into the other port causes the fluid pressure to act on two axially-spaced piston surfaces to provide an increased output force without increasing the diameter of the cylinder and piston and without increasing the pressure of the fluid.

Claims13

Dependent claims

A pressurized-fluid-operated actuator comprising:

a) a tubular outer cylinder defining an inner cylindrical surface, the outer cylinder having a longitudinal axis;
b) a piston slidably carried within the outer cylinder for axial movement therewithin and having a rod affixed thereto, the rod extending from an end of the piston in an axial direction relative to the outer cylinder, wherein the piston divides the outer cylinder into a head end chamber and a rod end chamber that is axially spaced from the head end chamber, and wherein the piston includes an inner cylinder;
c) a dividing wall extending transversely within the inner cylinder and at a fixed axial position relative to the outer cylinder to divide the inner cylinder into a first inner chamber and a second inner chamber;
d) a first fluid conduit in fluid communication with the head end chamber and with the first inner chamber for moving the piston and rod in a first axial direction relative to the outer cylinder, to cause the rod to move in a outward direction relative to the outer cylinder to provide a rod extension stroke when pressurized fluid is introduced into the first fluid conduit;
and
e) a second fluid conduit in fluid communication with the second inner chamber for moving the piston and rod in a second axial direction relative to the outer cylinder and opposite from the first axial direction, to cause the rod to move in an inward direction relative to the outer cylinder to provide a rod retraction stroke when pressurized fluid is introduced into the second fluid conduit.

3 more elements

Dependencies are inferred from the claim text.