Fluid handling – Systems – Multi-way valve unit
Patent
1997-11-07
1999-10-26
Fox, John
Fluid handling
Systems
Multi-way valve unit
141 98, F16K 1102
Patent
active
059710217
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention generally relates to the field of fluid systems, such as hydraulic power or cooling systems. More specifically, the present invention relates to methods and devices for filling closed loop fluid systems with fluid.
BACKGROUND OF THE INVENTION
Fluid systems are used in a wide variety of applications, particularly in the automotive field. For example, fluid systems are used to transfer power (e.g., automotive brakes), boost power (e.g., automotive power steering), and provide cooling (e.g., automotive radiator system or air conditioner). Fluid systems use a working fluid to transfer forces used in such applications. When in the confines of a closed loop fluid system, the working fluid is under pressure and is in a liquid form.
When filling a fluid system with a working fluid for the first time, it is important to remove as much air from the system as possible. Traditionally, initial working fluid introduction is performed by first evacuating air from the system through a port using a vacuum or similar device. The working fluid is then introduced into the system under low pressure (e.g., under its own weight). With a standard automotive power steering system, the evacuation and fill procedure can take up to about two minutes or more.
During the filling process, air can sometimes become trapped within the system. In most closed loop fluid systems, the presence of air in the system is undesirable. For example, in power steering systems air can cause the pump motor to burn out prematurely, and in brake systems air can cause decreased responsiveness of the brakes. In an attempt to remove trapped air from the system, a newly-filled system is typically "burped" by running the system through a number of cycles to force air trapped in the system to be brought to the surface of the fluid reservoir. The system is then topped off with an additional amount of working fluid to replace the air that has been removed. It is not uncommon for it to take 4 to 6 hours to adequately burp a closed loop fluid system.
SUMMARY OF THE INVENTION
An objective of the present invention is to decrease the time required to fill a fluid system with working fluid. Another objective of the present invention is to reduce the amount of air trapped within a fluid system during the filling process, thereby eliminating the need to burp the system.
To accomplish these objectives, the present invention provides a method for filling a fluid system wherein working fluid is injected unidirectionally into the system while air is simultaneously being removed. More specifically, the working fluid is injected through a fill port under pressure such that it flows through the system in one direction, thereby forcing the air out of the system. This inhibits the possibility of air being trapped within the system between volumes of working fluid. In one aspect, the method includes the steps of pressurizing fluid in preparation for injection into the fluid system, and injecting the pressurized fluid into the fluid system in a substantially unidirectional flow. For example, the fluid system can define a closed fluid path having first and second opposing directions, and the injecting step can include the steps of injecting the pressurized fluid in the first direction, and inhibiting flow of pressurized fluid in the second direction. By virtue of this method, there is no need to evacuate the air from the system prior to adding working fluid. As a result of this method, total fill time has been reduced to less than 30 seconds. Furthermore, there is no need to burp the system.
In one embodiment, the method further includes the step of removing old fluid from the system simultaneously with the injecting step. Preferably, the injecting step includes injecting the pressurized working fluid into the fluid system at a fill port, -and the removing step includes removing old fluid from the fluid system at an exhaust port separate from the fill port. For example, the removing step can include removing old fluid from the flui
REFERENCES:
patent: 4423741 (1984-01-01), Levy
patent: 4535802 (1985-08-01), Robertson
patent: 4691737 (1987-09-01), Sebo
patent: 4911211 (1990-03-01), Andersen
Fox John
SSI Technologies, Inc.
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