Membrane valve with structure for assuring a tight seal in the c

Details Membrane valve with structure for assuring a tight seal in the c Membrane valve with structure for assuring a tight seal in the c

1999-06-18

2000-09-12

Shaver, Kevin

Valves and valve actuation

Reciprocating valve

Diaphragm

251337, 25112917, A62B 902

Patent

active

06116576&

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a valve for regulating a flow of gas, of the type have a valve body with an inlet for the gas to be regulated and an outlet for a regulated flow of a fluid, a valve seat with a valve opening, a moving closure part having a tensioned membrane mounted inside the valve body and a plunger, which is movable by an actuator arrangement, whose end acts on the membrane, causing the closure part to close and open the valve opening and regulate the flow of gas through same.
2. Description of the Prior Art
A valve of the above general type is shown and described in U.S. Pat. No. 5,265,594. It is highly important, particularly in the supply of gas to a patient on a ventilator, to ensure that the amount of gas supplied through such a valve is regulated with great accuracy and repeatability. In order to achieve this, the membrane must lift off the valve seat, parallel to same, every time the valve opens. When the membrane is closed with by the end of the plunger, which is flat with a surface area somewhat larger than the surface area of the valve seat, the end of the plunger must press against the valve seat with an evenly applied force. This can sometimes be difficult to achieve, since the valve seat and plunger are not always perfectly aligned. If their positions are disturbed so e.g. the plunger tilts in relation to the valve seat, this tilted, often uncontrolled, plunger position can result in leakage between the membrane and valve seat and to impaired regulation of gas flow through the valve. Even small angular deviations can greatly impair regulation of the flow of gas.


SUMMARY OF THE INVENTION

It is an object of the invention is to provide a valve of the type initially described where in a flow of gas can be regulated, using simple and, accordingly, inexpensive means, with great accuracy and repeatability and which forms a hermetic seal when in the closed position.
The above object is achieved in accordance with the present invention in a valve having a rigid, flat plate, arranged opposite the valve seat, said plate having a surface area which is at least equal to the surface area of the valve seat, the plate being arranged in such a way that it follows the membrane's axial movements and can be tilted in relation to the plunger's longitudinal axis. The part of the plunger end acting on the membrane has a surface area which is smaller than the surface area of the valve seat. As a result of the surface area of the part of the plunger end acting on the membrane and on the plate respectively, the rigid plate is able to tilt towards the plunger when the valve opening is opened or closed respectively, thereby compensating for any misalignment of the plunger or valve seat, and controlled, repeatable membrane movement is accordingly achieved. The end of the plunger, according to the invention, can advantageously be convex.
According to one advantageous embodiment of the valve according to the invention, the plate is part of the membrane. The plate can be advantageously integrated into the membrane or also glued onto it.
According to an additional embodiment of the valve according to the invention, the plate is part of a spiral-shaped washer which presses firmly against the membrane, said washer being mounted inside the valve body. As a result, the washer and, accordingly, the plate are a separate part which can be replaced when needed without any need to replace the membrane as well.
According to the invention, the plate can also be part of leaf spring which presses firmly against the membrane, said leaf spring being mounted inside the valve body. Here, the plate can also be replaced when needed.
The spiral-shaped washer and leaf spring can be advantageously arranged on the side of the membrane facing away from the valve seat.
According to the invention, the plate can be made of metal, preferably spring steel, about 0.15 mm thick.


DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration, partly in section, of a valve with a

REFERENCES:
patent: 4805871 (1989-02-01), Nakamura
patent: 4915353 (1990-04-01), Danko
patent: 4988074 (1991-01-01), Najmolhoda
patent: 5186434 (1993-02-01), Nishimura et al.
patent: 5265594 (1993-11-01), Olsson et al.

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