Fluid handling – Line condition change responsive valves – With separate connected fluid reactor surface
Reexamination Certificate
2000-01-13
2001-03-27
Hepperle, Stephen M. (Department: 3753)
Fluid handling
Line condition change responsive valves
With separate connected fluid reactor surface
Reexamination Certificate
active
06206031
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a pressure compensating liquid flow regulator, and more particularly to such a regulator which is of reduced length.
The prior art teaches a liquid flow regulator which controls hydraulic flow to a predetermined level, regardless of the differential pressure across the regulator. For example, such a flow regulator is available under the tradename 500 Flosert from the Lee Company of Westbrook, Conn. The product maintains hydraulic flow at a predetermined level, regardless of the differential pressure across the regulator, by maintaining a constant pressure drop across a fixed or sensing orifice. The spring or biasing means of the flow regulator is disposed outside of the metering poppet, thus limiting the utility of the regulator in situations affording only a limited axial length for the regulator. For example, a slot for a flow regulator may have an installation bore length of less than 1 inch, while an installation bore length in excess of 2 inches is required for the prior art regulator. Accordingly, it would be desirable to have a flow regulator having an installation bore length of less than 1 inch (about half of the installation bore length of the prior art regulator), and preferably no more than 0.9 inch.
The prior art flow regulator did not prove to be entirely satisfactory in use because it could not regulate the liquid flow to a sufficiently tight range to be useful for particularly demanding customer applications. Thus whereas the prior art device regulated flow to about ±10%, critical applications require regulation of the flow to about ±3% (less than a third of the variation of the prior art regulator), and preferably no more than ±0.7%.
Accordingly, it is an object of the present invention to provide a educed length, pressure compensating liquid flow regulator.
Another object is to provide such a regulator having an installation bore length of less than 1 inch, and preferably no more than 0.9 inch.
A further object is to provide such a regulator which can regulate flow to about ±3%, and preferably no more than ±0.7%.
It is also an object of the present invention to provide such a flow regulator which is simple and economical to manufacture, maintain and use.
SUMMARY OF THE INVENTION
It has now been found that the above and related objects of the present invention are obtained in a reduced length, pressure compensating liquid flow regulator comprising a poppet, a retainer means, a seat, a biasing means and a housing. The magnitude of the spacing between the seat front face and the cylinder rear orifice is self-adjusting as an inverse function of the magnitude of the liquid flow rate, thereby to provide a substantially constant liquid flow rate through the regulator by compensating for variations in the pressure differential across the sense orifice.
More particularly, a poppet defines a longitudinally extending hollow cylinder having a front surface defining a front sense orifice and a rear surface defining a rear orifice, the cylinder orifices defining a liquid passageway therethrough. A retainer means maintains biasing means disposed at least partially within the cylinder, the retainer means including a front sidewall surface defining a central aperture and a rear sidewall surface defining rear side slots. The retainer central aperture and side slots define a liquid passageway therethrough. A seat has a closed front face spaced from and facing the cylinder, side passages rearwardly of the seat front face, and a downstream passage, the seat passages defining a liquid passageway therethrough. A biasing means disposed at least partially within the cylinder biases the cylinder rear orifice longitudinally away from the seat, the biasing means defining a liquid passageway therethrough. A hollow housing slidably receives the cylinder and fixedly receiving the retainer means and the seat, the housing directing liquid flow from the annular space and the retainer side slots into the seat side passages.
Preferably the retainer means slidably maintains the biasing means disposed entirely within the cylinder, the seat front face is flat, and the outer circumferences of the cylinder rear surface and the cylinder front surface are substantially equal.
In a preferred embodiment, the surface areas defined by the outer diameters of the poppet front surface and the poppet rear orifice, respectively, are substantially equal. Thus, the pressure differential between the poppet front and rear surfaces is substantially proportional in magnitude to the force exerted by the biasing means per unit of the substantially equal surface areas. Preferably the pressure differential is substantially equal in magnitude and opposite in direction to the force exerted by the biasing means per unit of the substantially equal surface areas.
Preferably the cylinder rear surface and the retainer front sidewall surface form an outwardly tapered annular space therebetween.
REFERENCES:
patent: 3120243 (1964-02-01), Allen et al.
patent: 3805824 (1974-04-01), Robbins, Jr.
patent: 4921547 (1990-05-01), Kosarzecki
patent: 5251655 (1993-10-01), Low
Pp. C16 through C19 from The Lee Company Technical Hydraulic Handbook, 1997 Release 10.1.
Amster Rothstein & Ebenstein
Hepperle Stephen M.
NMB (USA) Inc.
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