Fluid handling – Self-proportioning or correlating systems – Self-controlled branched flow systems
Reexamination Certificate
1999-12-03
2001-09-11
Hepperle, Stephen M. (Department: 3753)
Fluid handling
Self-proportioning or correlating systems
Self-controlled branched flow systems
C137S113000
Reexamination Certificate
active
06286538
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present application is directed to an air brake system, and is more particularly directed to a double check valve commonly used in an air brake system. It will be appreciated, however, that the invention may be used in related environments and applications that encounter the same types of problems.
2. Discussion of the Art
Presently available check valves use a shuttle as the valve member that is interposed between a pair of inlet or supply passages. The shuttle selectively seals one of the inlets in response to air flow, and more precisely, the pressure differential imposed on the shuttle. The shuttle has a significant mass that includes an enlarged rubber core encased in a metal sleeve with elastomeric sealing ends extending from opposite ends of the sleeve for selective, sealing engagement about the inlet ports of the check valve assembly. In addition, a guide sleeve or tube is typically inserted in the valve body and includes side wall slots to allow air communication through the guide tube. The guide tube assists in selective axial movement of the valve member in response to the flow rate. Thus, the shuttle or double check valve member moves or shuttles between first and second positions depending on whether the pressure or flow rate is higher or lower than the other port. Due to the large mass of the currently used shuttle, the valve is typically mounted in a horizontal orientation for operation. If mounted vertically, a high flow rate is needed to move the shuttle upward and seal the port in the elevated position when air is supplied to the port located in the lower position. Thus, the vertically mounted check valve can encounter less than desirable operation of the valve, i.e., air can be bled from both inlets at low flow rates. Improvements are desired to assure that, in a system where two supplies feed a common delivery, the high pressure supply side will communicate with the delivery port and not communicate or flow into the low pressure supply side.
Moreover, the presently available assembly is relatively expensive because of the materials of construction and labor-intensive assembly features. Thus, in an effort to reduce the weight, as well as minimize the manufacturing cost, improvements are desired.
SUMMARY OF THE INVENTION
The present invention provides a double check valve assembly for an air brake system that is light weight, is less expensive than present arrangements, and is not sensitive to orientation of the valve.
According to the invention, a housing has first and second inlets that communicate with a valve chamber defined therein. A lightweight, non-metallic valve member has elastomeric seals formed at first and second ends for selectively preventing communication between one of the inlets and the outlet.
According to another aspect of the invention, the valve member is a plastic shuttle dimensioned for sliding movement in the valve chamber. The shuttle member has a reduced dimension central portion and enlarged dimensions at opposite ends where the seals selectively engage about the inlet ports.
A primary benefit of the present invention is the increased sensitivity of the valve to low flow and low pressure differential conditions.
Still another benefit of the present invention resides in the decreased sensitivity to mounting orientation of the valve assembly.
Still another benefit garnered from the present invention is the decreased cost.
Still other benefits and advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description.
REFERENCES:
patent: 1791449 (1931-02-01), Kennedy
patent: 2821972 (1958-02-01), Banker
patent: 5437300 (1995-08-01), Winnie et al.
Fent James E.
Kubik James M.
AlliedSignal Truck Brake Systems Co.
Hepperle Stephen M.
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