Fluid handling – Line condition change responsive valves – With separate connected fluid reactor surface
Patent
1999-03-18
2000-12-26
Hepperle, Stephen M.
Fluid handling
Line condition change responsive valves
With separate connected fluid reactor surface
G05D 701
Patent
active
061643211
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a liquid flow regulator. In particular, the present invention is suitable for use as an adjustable-rate flow regulator utilizable in an infusion set.
WO 96/03166 (Baxter) discloses a fluid flow regulator provided with a housing and a flexible diaphragm clamped in the housing along its periphery, prebiased so that in its state of rest it assumes an arcuate shape, prestressing the diaphragm towards the outlet, thereby reducing its sensitivity by causing the diaphragm to lose its elastic properties, especially in the range essential for improved control sensitivity required for low rate flows such as those normally used for intravenous administration of fluids.
In U.S. Pat. No. 5,421,363, there is described an adjustable- rate flow regulator with a greatly enhanced accuracy and improved repeatability, over similar prior art flow regulators. This flow regulator is suitable to operate at low dripping rates reaching, for example, 2 ml/hr, at a low pressure drop across the diaphragm of e.,g., only 40 cm of water, in view of a restricted pressure head. The regulator functions as a negative feedback closed loop control system. Due to the relatively long flow attenuating passageway associated with the feedback portion of the system, as well as due to other time constants of the system during operation, the latter tends to become inaccurate, instable and to oscillate vigorously about its set operating flow rate.
SUMMARY OF THE INVENTION
It is therefore a broad object of the present invention to overcome the shortcomings of the above-described and other prior art flow regulators and to provide a flow regulator having improved control sensitivity.
It is a further object of the present invention to provide a flow regulator having improved output flow stability.
In accordance with the present invention there is therefore provided a liquid flow regulator, comprising a split housing including an upper portion connectable to a source of liquid to be dispensed, said upper portion having an inlet port and a lower portion engaging said upper portion and having a control output port leading to the consumer of the liquid, an elastically deformable diaphragm disposed in said housing and defining with a bottom surface of said upper housing portion a first chamber, and with a top surface of said lower housing portion in which said output control port is made, an output control chamber, and a tubular flow attenuator disposed in said housing, forming a liquid flow path between said first chamber and said control chamber, characterized in that the thickness of said diaphragm is at least equal to its working, amplitude being defined by the distance between said diaphram in its state of rest and said output control port.
In a preferred embodiment, the invention further provides a liquid flow regulator, characterized in that said regulator is an adjustable rate regulator, said upper and lower housing portions being rotatably engaged with each other, said tubular attenuator is rotatably engaged with one of said housing portions but non-rotatable relative to the other portion, wherein the inner wall surface of said tubular attenuator defines in conjunction with a housing portion a system of flow-attenuating ducts of said liquid, the flow-attenuating effect of which ducts can be varied to adjust the rate of flow of said liquid.
The invention will now be described in connection with certain preferred embodiments with reference to the following illustrative figures so that it may be more fully understood.
With specific reference now to the figures in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in mo
REFERENCES:
patent: 3886968 (1975-06-01), Murrell
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