Caterpillar Inc.

J Roger Weber

Scott F Shafer

Steven Francis Meister

Charles R Miller

Tsu P Shyu

Thomas S Carroll

David R Orr

A spool valve comprising a body portion with a general center bore, three annular chambers and a seal land between adjacent chambers, a spool portion slidably disposed in the bore and having two semicircular circumferential grooves to form a spool land associated with each of the chambers, the spool lands and seal lands being so disposed that when the spool is in a first position the annular chamber on one end is in fluid communication with the center chamber and the spool land associated with the one end chamber and the spool land associated with the center chamber are equidistant from the adjacent seal land and the other seal land and the spool land associated with the chamber on the other end cooperates with the other seal land to form a seal between the center chamber and the other end chamber and when in a second position the annular chamber on other end is in fluid communication with the center chamber and the spool land associated with the other end chamber and the spool land associated with the center chamber are equidistant from the adjacent seal land and the other seal land and the spool land associated with the chamber on the one end cooperates with the other seal land to form a seal between the center chamber and the other end chamber, whereby the flow forces of high pressure fluid acting on the spool cancel out and the force required to move to the spoon between positions is minimized

Flow force spool valve

The present invention is an apparatus 10 for hydraulically slowing a member (12), preferably an engine poppet valve, to an acceptable impact seating velocity as the valve (12) is moved from open to closed. The poppet valve (12) has a stem (16) having a first portion (18) connected through a stepped portion (20) to a second portion (22) having a greater cross-sectional area than the first portion (18). The valve (12) rides within a guide body (28) having an opening (34) in an end wall (32) thereof through which the first portion (18) of the stem (16) extends. A hydraulic fluid space (50) is formed by the guide body (28) and the valve (12). As the valve (12) closes, fluid is forced out of the space (50) through a first fluid exit opening (66). As the valve (12) nears its seat (44), the fluid still in the space (50) is forced out through a second fluid exit opening (68) through which the rate of flow is less than the rate of flow through the first fluid exit opening (66). As the valve (12) continues closing, fluid still in the space (50) is compressed, increasing its hydraulic pressure and creating a resistive force to further movement of the poppet valve (12), thereby slowing it to an acceptable impact velocity.

Engine valve seating velocity hydraulic snubber

An apparatus adjustably controls intake and exhaust valve movement and fuel injection of an engine. Valve movement and injection is adjustably controlled in response to electrical signals delivered to a piezoelectric motor which in turn delivers hydraulic signals through a single spool valve.

Apparatus for adjustably controlling valve movement and fuel injection

A system in which movement of a first member from a first position to a second position is translated through fluid in a fluid chamber to movement of a second member from a first position to a second position, the system having a pressure equalization line in communication with the fluid chamber allowing fluid to flow into the chamber when the second member is at its first position and out of the chamber when the second member nears the first position when returning from its second position towards its first position.

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Chillicothe, IL, United States of America

J Roger Weber