Fluid handling – Line condition change responsive valves – With separate connected fluid reactor surface
Reexamination Certificate
1999-08-24
2001-02-20
Hepperle, Stephen M. (Department: 3753)
Fluid handling
Line condition change responsive valves
With separate connected fluid reactor surface
Reexamination Certificate
active
06189564
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to fluid transfer and metering, and particularly to adjustable valves for controlling the rate of fluid flow.
BACKGROUND OF THE INVENTION
Many types of equipment and industrial processes require accurate control of the flow of liquid and gaseous fluids over a broad range of fluid pressure and flow rates. It is particularly important that flow controllers for such equipment and processes be able to accurately meter fluid flow over a broad range of flow rates. One problem with many prior art valves is that the amount of torque required to adjust the valve to alter the flow rate increases proportionally to fluid pressure within the valve. This is because the fluid pressure is operating in the valve components that must be rotated during valve adjustment. As a result, adjustment can be difficult to accomplish at high pressures.
Many conventional flow control valves utilize a piston carrying a needle that acts against a spring set contained between the piston and the bottom wall of the valve chamber in which the valve seat is formed. To adjust the valve, the bias force of the piston spring set can only be adjusted from an external source, or an adjustable valve seat has to be provided. An improvement on such valves is provided in the metering valve of U.S. Pat. No. 5,427,139 to Hilton, the disclosure of which is hereby incorporated by reference. This valve overcomes some shortcomings of conventional valves by including an adjustable floating piston and needle assembly that provides for adjustment against internal differential pressure independent of the total system pressure.
While representing an advance in adjustability and metering accuracy, the Hilton '139 metering valve maintains its highest degree of accuracy of flow regulation only in a narrow range. Hardware modifications are required to operate in other ranges with the same degree of accuracy.
An industry-recognized measure of the ability of a valve to control flow rate over a range of flow rates is the “turndown ratio”. Thus, if a valve has a “turndown ratio” of
10
:
1
and is capable of accurately regulating a maximum flow rate of 100 liters per hour, then the smallest flow rate that the valve can accurately regulate is 10 liters per hour (i.e., one tenth of the maximum flow rate). Typically, the “turndown ratio” of prior art valves is from about 4:1 to about 10:1. Thus, there is a need for a valve that can accurately regulate a wide range of fluid flow rates and that requires a relatively small amount of torque to adjust the flow rate of the valve during operation.
It is also desired to have a metering valve that is not unduly sensitive to pressure fluctuations in the system. This is particularly the case for downstream pressure fluctuations that may induce a sinusoidal flow rate fluctuations in conventional valves.
SUMMARY OF THE INVENTION
The present invention provides adjustable flow control valves for controlling flow of a fluid from a fluid supply. The valves of the present invention can accurately regulate a wide range of flow rates and require a relatively small amount of torque to adjust the flow rate of the valve during operation. The valves of the present invention include a flow control component and a pressure control component. The flow control component includes (I) a housing defining a valve chamber having a first end and a second end, an inlet port opening into the first end of the valve chamber for placing a fluid supply in fluid communication with the valve chamber, and an outlet port for fluid flow to exit from the second end of the valve chamber; (II) a floating piston slidably mounted within the valve chamber between the inlet and outlet ports; (III) a passage connecting the valve chamber first end and valve chamber second end; (IV) a valve seat disposed within the housing in the second end of the valve chamber, upstream of the outlet port; and (V) a valve member carried by the floating piston. Preferably the valve member is selectively positionable relative to the piston and to the valve seat in order to restrict or facilitate fluid flow through the outlet port. The flow control component preferably includes a biasing spring disposed within the valve chamber second end to bias the floating piston toward the valve chamber first end. The pressure control component includes: (I) a housing defining a valve chamber having a first end and a second end, a first inlet port opening into the first end of the valve chamber for placing a fluid supply in fluid communication with the valve chamber, a second inlet port for placing the valve chamber second end in fluid communication with the outlet port in the valve chamber second end of the flow control component, and an outlet port for fluid flow to exit from the second end of the valve chamber to a downstream fluid destination; (II) a floating piston slidably mounted within the valve chamber between the first inlet port and the outlet port; (III) a valve seat included in the housing in the second end of the valve chamber, upstream of the outlet port; and (IV) a valve member carried by the floating piston. The pressure control component preferably includes a biasing spring disposed within the valve chamber second end to bias the floating piston toward the valve chamber first end.
In a first preferred embodiment of the adjustable flow control valve of the present invention, the valve member of the flow control component is mounted within an internal passage of the piston for selective advancement within the internal passage relative to the piston. Advancement of the valve member within the piston determines the position of the valve member relative to the valve seat to control the rate of flow of fluid through the valve chamber. A rotatable valve shaft has a work end external of the housing and a keyed engaging end passing through the housing into the first end of the valve chamber. The keyed engaging end of the valve shaft is slidably engaged with a keyed engaging surface defined by the valve member. The valve shaft rotates within the housing, and drives rotation of the valve member to translate the valve member within the piston. Selective rotation of the valve shaft causes advancement of the valve member within the internal passage of the piston to adjust the rate of flow of fluid through the valve chamber. The passage connecting the valve chamber first end and the valve chamber second end is defined through the piston, radially offset from the valve member. An orifice assembly is mounted within this passage. Alternately, the passage connecting the first and second ends of the valve chamber can be formed axially through the valve member, or can be formed in the wall of the valve housing.
In a second preferred embodiment, the piston in the flow control component carries a non-adjustable valve member and the orifice assembly. The valve member carried in the piston of the pressure control section is adjustable with a valve shaft.
In a third preferred embodiment, neither the piston in the flow control section nor the piston in the pressure control section includes an adjustable valve member. Rather than being carried in the piston of the flow control section, an external orifice is provided in a passage placing the first and second ends of the chamber of the flow control section in fluid communication. This orifice, which may be placed in a passage within the chamber housing or externally thereof, is adjustable.
In a fourth preferred embodiment, the valve members carried in the pistons of both the flow control and pressure control sections are adjustable.
The adjustable flow control valves of the present invention are capable of accurately regulating fluid flow rates of from about two liters per hour to about 1000 gallons per day for the first preferred embodiment summarized above, and up to 15,000 gallons per day for the third preferred embodiment summarized above. These flow rates are provided for illustration only, and values in accordance with the present invention may be scaled up or down to handle o
Amhi Corporation
Christensen O'Connor Johnson & Kindness PLLC
Hepperle Stephen M.
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