Automatic temperature and humidity regulation – Thermostatic – In fluid controlled
Reexamination Certificate
2001-10-05
2003-03-11
Tapolcai, William E. (Department: 3744)
Automatic temperature and humidity regulation
Thermostatic
In fluid controlled
C236S09900R
Reexamination Certificate
active
06530529
ABSTRACT:
FIELD OF THE INVENTION
In general, the invention relates to hydraulic systems used in the operation of heavy equipment. More specifically, the invention relates to electro-hydraulic or hydraulic systems used for regulating pressure in the operation of heavy equipment, including but not limited to backhoes, excavators, skid steer drives, crawler drives, outriggers, and wheel loaders.
BACKGROUND OF THE INVENTION
In general, heavy equipment used in construction trades and industry employ hydraulic systems to perform digging, loading, craning, and like operations. The speed and direction of the heavy equipment armatures are controlled with hydraulic valves. The controlling valves are manipulated by a skilled operator who typically uses a sense of touch to predict the probable motion of the heavy equipment. The sense of touch is the memorization of viewable mechanical motion characteristics, as they are associated with specific hand operations. It is the sense of touch that the operator relies upon to perform operations such as load movement into confined spaces and precision excavation. As the heavy equipment executes the operators commands, the hydraulic fluid moves quickly throughout the hydraulic system producing kinetic energy. The energy is transferred as vibration and heat into the hydraulic fluid, hydraulic lines, and associated equipment. The increasing heat energy reduces the viscosity of the hydraulic fluid, thus producing a decrease in fluid pressure. The decreased fluid pressure alters the motion characteristics of the heavy equipment, which affects the accuracy achievable by the operator. Thus, there is a need for a hydraulic system capable of performing systematically regardless of fluid temperature.
SUMMARY OF THE INVENTION
One aspect of the present invention provides a hydraulic system for regulating fluid pressure of heavy equipment comprising a main body, a thermal element positioned within the main body, a pin positioned adjacent to the thermal element, and an orifice spool in communication with the pin. The thermal element expands to force the pin to reposition the orifice spool, and restrict fluid flow through the main body.
Another aspect of the present invention provides a method for determining changes of pressure in a hydraulic system based on temperature changes, expanding a thermal polymer when the fluid temperature increases and contracting the thermal polymer when the temperature decreases, which meters fluid flow based on the expanding and contracting of the thermal polymer.
The foregoing and other features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiment, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention rather than limiting, the scope of the invention being defined by the appended claims and equivalents thereof.
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MacLeod Ian J.
Stoever Guy T.
Case Corporation
Trausch A. N.
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