Liquid purification or separation – Flow – fluid pressure or material level – responsive – Check valve
Reexamination Certificate
1997-10-01
2001-05-22
Drodge, Joseph W. (Department: 1723)
Liquid purification or separation
Flow, fluid pressure or material level, responsive
Check valve
C210S117000, C210S287000, C210S446000, C137S856000, C096S134000, C096S154000
Reexamination Certificate
active
06235192
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to filter driers and more particularly to a bidirectional flow filter drier which is especially useful in heat pump systems or any other air conditioning or refrigerant systems where fluid flows may be reversed.
Bidirectional flow filter drier assemblies are well-known in these fields and provide convenient, economical devices which utilize a common filter drier medium and a minimum of interconnections with the plumbing of the system which is advantageous both from the standpoints of minimal original equipment and ease of maintenance and repair.
One particularly useful biflow drier is shown in Griffin, U.S. Pat. No. 4,954,252, which is owned by the assignee of the present invention. In the Griffin drier, a simplified and reliable biflow filter drier structure is provided which utilizes a minimal number of components. A valving structure in the filter drier is easily fabricated from punched metal parts and readily assembled by spot welding techniques. The valving structure includes a pair of identical check valve assemblies and a single molded desiccant core. The check valve assemblies are located at opposite ends of the core and each includes stainless steel reed-type flapper valves formed from a single sheet of material. While the Griffin drier structure is appropriate for many applications, the desiccant core provides both filtration and water removal functions, which can reduce the operational life of the desiccant. The desiccant in the core has small openings which can plug or clog, particularly on the surface of the core, and which may require frequent drier replacement.
As such, it is believed that there is a demand for a further improved bidirectional flow filter drier which has a structure where the desiccant core is not required to provide a filtration function, but which rather performs primarily a water-removing function and which thereby extends the useful life of the filter drier.
SUMMARY OF THE INVENTION
A new and unique bidirectional flow filter drier is provided where a depth-type filter media layer surrounds the desiccant core in the housing of the drier. The filter media layer extends against and along the outer surface of the desiccant core, preferably in one or more rings extending circumferentially around the core. The outer filter preferably has a greater filtration efficiency than the desiccant core to remove particles before the particles enter the core. The depth type of media for the outer filter captures the particles throughout substantially the entire thickness of the media, which extends the operational life of the desiccant material.
An additional filter media layer can be provided at both ends of the desiccant core. The end filters are disc-shaped and are disposed between the end surface of the core and the valve assembly associated with the end surface. The end filters separate fine particles from the fluid exiting axially from the core (depending upon the direction of fluid flow) and prevent the particles from being returned to the fluid system. A portion of the fluid passing through the drier can also pass directly from the outer filter to the end filters and bypass the desiccant core.
The filter drier includes a tubular housing, a pair of end caps with flow port fittings at either end of the housing, and a pair of identical check valve assemblies supporting opposite ends of the desiccant core. Each check valve assembly is preferably a spot-welded structure of a centering plate, a core support cup, and an intermediate flapper valve plate. The valve plate includes a pair of flapper reeds extending in opposite directions from a central support surface and normally covering a central valve opening in the core support cup, and at least one offset opening in the centering plate. The valves plates are moved to open positions by fluid pressure and are prevented from overtravel and overstressing by stop surfaces on both the core support cup and the centering plate. The flapper valve plates are formed from a single thin sheet of metal, preferably stainless steel.
A screen is provided against the outer end surface of each of the end filters to support the end filters. Perforated plates can also be provided against each of the inner and outer end surfaces of the end filters to support the end filters. The perforated plates on the inner end surface of the end filters also support the ends of the desiccant core and the ends of the outer filter. The brass screen and perforated plates are disposed within and supported by the core support cup in the check valve assemblies.
Further features of the present invention will become apparent to those skilled in the art upon reviewing the following specification and attached drawings.
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Griffin Gary E.
Melfi James J.
Cecil Terry K.
Drodge Joseph W.
Hunter Christopher H.
Parker-Hannifin Corporation
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