Automatic fluid control valve

Details Automatic fluid control valve Automatic fluid control valve

1998-09-14

2001-01-09

Chambers, A. Michael (Department: 3753)

Valves and valve actuation

With correlated flow path

Valve operated by joining flow path sections

C604S256000, C604S905000

Reexamination Certificate

active

06170800

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a fluid control valve, and more particularly to an automatic valve having a valve element maintained in slidable engagement with a tube member.
BACKGROUND OF THE INVENTION
Flow control valves for restricting or permitting fluid flow come in many shapes and sizes, and are made of a wide variety of materials depending on their intended use.
Typically, flow control valves such as butterfly valves and gate valves are used to control flow of fluid by moving a mechanical member into and out of the flow path to partially or completely block the flow path. Other types of valves, for example roller clamps used in medical intravenous apparatus, control flow by pinching the plastic tubing through which the fluid flows. Still other types of valves operate by controlling the length of the flow path, and therefore the resistance to flow, through the valve.
Despite the wide variety of valves that have been used heretofore, there is a continuing need for improved flow control valves that have cost, ease of use, functional, and other advantages compared to prior flow control valves. A significant need exists for a valve that contains a minimum number of parts, and that those parts form a sealed access port which can be effectively cleaned by an alcohol wipe. There is also a need for a flow control valve that has minimal dead space to minimize the area in which air can become entrapped; one that is easily purged of air, and one that has a minimal priming volume.
DESCRIPTION OF THE PRIOR ART
Prior art valves have the tendency to create a pressure wave when a needle or syringe tip is introduced into the valve because the valve seal must displace a significant volume of fluid or air in order to move and break the seal at the valve seat. This pressure wave can introduce a pressure wave into the bloodstream downstream from the valve. Such valves commonly have only a fully closed or fully open position, with little ability to control the fluid volume displaced by the introduction or withdrawal of a needle or syringe tip. Certain patients, particularly neonates, young children, and people with blood pressure disorders, are very sensitive to fluid pressure changes in the bloodstream. Prior art valves can introduce a back pressure volume wave into the bloodstream of these patients, potentially causing fluid overload and pressure receptor overload, and consequent injury. It would be desirable to have a valve that had a minimized volume of fluid or air that was displaced. Additionally, it would be desirable to have a valve that allowed a user to withdraw an amount of fluid while inserting a needle or to inject an amount of fluid when withdrawing a needle in order to balance out the fluid pressure and volume in the bloodstream.
U.S. Pat. No. 5,215,538, issued to Larkin discloses an in-line valve having a mated pair of tube members and a valve member comprising an elastomeric membrane having flow holes therein and a projection extending from the membrane. The membrane is secured across the passageway between the two tube members by a rim which engages the ends of the tube members when mated. The membrane is “tensioned across and in sealing engagement with the annular valve seat.” The projection is urged downward when a connector engages the projection and the valve seal is broken, permitting fluid flow.
The inlet tube of Larkin must be of a certain minimum depth to engage and lock with a standard luer taper connector. The projection associated with the valve membrane is inserted during assembly into the inlet tube. Even with full insertion there remains an empty well that is exposed to the air and which can collect dirt and contaminants. This well cannot easily be cleaned. If the projection were modified to be long enough to fill the inlet tube, when a connector was inserted the amount of downward displacement of the projection would likely cause the valve membrane to rupture. Therefore is not likely that Larkin could be adapted to remedy this deficiency.
Larkin utilizes a valve member in which the sealing surface is also the elastomeric member. In other words, the seal itself must stretch both laterally and axially. A problem with this type of design is that the deformation of the valve seal may not be even when the projection is moved downward to break the seal, resulting in possible fluid leakage around the membrane. Furthermore, the elastomeric membrane cannot be deformed axially significantly if it is to maintain the valve seal. It would be desirable to have a valve seal that does not require lateral deformation so as to ensure a proper fluid tight seal.
In Larkin, once the luer connector moves the projection downward even partially the valve seal is broken. Until the connector is locked into place there exists the possibility of fluid leakage back through the seal and the luer taper inlet tube to the inlet connector because there is no secondary seal anticipated that is maintained until the connector is locked in place. Where there is substantial back pressure this may result in contamination of the inlet fluid.
It would be desirable, then, to have a fluid control valve which would utilize a valve that is held in displaceable sealing engagement with a valve sealing surface and that would in a closed position completely fill the connector passageway so as to form a seal that would be cleanable by an alcohol wipe.
U.S. Pat. No. 5,360,413, issued to Leason et al. discloses a needleless access device having an elastic valve member sandwiched between two rigid tubes. Leason has a wiper seal as part of the valve element. As the valve element is forced downward or upward by a luer tip, the valve element acts as a plunger and the wiper seal creates a pressure wave that is undesirable. Additionally, the space between the wiper seal and the inner wall of the upper tube member can be a site for collection of contaminants. It would be desirable for a valve assembly to obviate the need for a wiper seal and eliminate the pace between the valve element wall and the upper tube inner wall, yet would be sealed against contaminants and have a wipable top surface.
Additionally, Leason et al. has a significant dead space in the lower tube member which can trap air, which needs to be avoided when injecting fluid into a person. It would be desirable to have a valve assembly designed to eliminate the air trap dead space and to minimize the overall volume within the valve assembly.
SUMMARY OF THE INVENTION
The present invention generally provides an automatic fluid control valve having an upper and a lower rigid hollow tube members that can be matingly joined. A valve element mounted within the valve assembly can be slidingly moved within the upper tube member.
A first preferred embodiment of the present invention provides a first rigid tube member having a top, a bottom, a first portion containing a first inner wall defining a first passageway having a first diameter, and having a flared second portion extending axially from the first portion and containing a second inner wall defining a second passageway, and defining a primary valve sealing surface. A second rigid tube member has a top and a bottom, an inner passageway defined therein by an inner wall. The first and second tube members are capable of mating engagement with axial alignment, the bottom having a male luer connection defined therein.
An elastomeric cylindrical valve element assembly comprises a first portion having an outer wall, a top surface, the top surface having an aperture and a bore defined therein, the aperture having an inwardly projecting flange, the bore containing a beveled portion and a lip, and the top surface having an outwardly projecting flange capable of forming a seal with the first passageway of the first rigid tube member when inserted therein and when in a closed position; a rounded concave bottom surface; a tubular second portion extending downward from the first portion; a third portion extending downward from the second portion and flaring outward, the third portion angling outwa

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