Rotary expansible chamber devices – With wear surface treatment or integrally plated wear layer
Reexamination Certificate
1999-11-15
2001-06-26
Denion, Thomas (Department: 3748)
Rotary expansible chamber devices
With wear surface treatment or integrally plated wear layer
C418S171000, C418S166000
Reexamination Certificate
active
06250900
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the field of hydraulics, more particularly, positive displacement hydraulic pumps and motors having gerotors, gears, or vanes.
Positive displacement pumps and motors that include gerotors, gears, or vanes have inherent volumetric losses due to the side clearances built into the mechanism. Side clearances exist between the rotary element or fluid displacing mechanism (gerotor, gear, or vane) and the axially adjacent members, usually a housing or end cap wall. The volumetric losses are a function of the side clearances to the third power. Thus, the volumetric losses are greatly affected by the side clearances. If side clearances can be minimized, volumetric efficiency greatly increases. However, manufacturing tolerances and deflection typically dictate the side clearances and limit efficiency.
Therefore, a primary objective of the present invention is the provision of a positive displacement pump or motor with improved volumetric efficiency.
Another objective of this invention is the provision of a positive displacement pump or motor having near-zero side clearance.
Another objective of this invention is the provision of a positive displacement pump or motor having a layer of abradable sacrificial coating material applied to the housing wall adjacent the rotary element, the coating wearing-in to establish a minimal side clearance and thereby high volumetric efficiency.
Another objective of this invention is the provision of a positive displacement pump or motor that is economical to produce, easy to assembly, and reliable and durable in use.
These and other objectives will be apparent from the drawings, as well as from the description and claims that follow.
SUMMARY OF THE INVENTION
The present invention relates to the field of hydraulics, more particularly, positive displacement hydraulic units, such as pumps and motors having gerotors, gears, or vanes.
The positive displacement of hydraulic unit of this invention includes a housing having a chamber formed therein with a circumferential surface bounded by a pair of spaced apart end walls. A rotary element for displacing fluid rotatably mounts in the chamber. A layer of non-metallic abradable coating material is positioned between an end wall of the chamber and the adjacent side wall of the rotary element so as to provide a near-zero side clearance for the rotary element and thereby high volumetric efficiency for the hydraulic unit.
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Denion Thomas
Sauer-Danfoss Inc.
Trieu Theresa
Zarley McKee Thomte Voorhees & Sease
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