Surgery – Respiratory method or device – Means for supplying respiratory gas under positive pressure
Patent
1996-03-29
1997-11-25
Miller, V.
Surgery
Respiratory method or device
Means for supplying respiratory gas under positive pressure
12820418, A62B 902
Patent
active
056900988
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a servo gas regulating valve comprising a housing having an inlet chamber and an outlet chamber, a main valve body cooperating with a seat separating the inlet chamber from the outlet chamber, a piston or the like separating the outlet chamber from a servo chamber, and a control valve arranged to be opened and closed by the main valve body.
Systems for supplying breathing gas are generally based on a regulated supply from reservoirs containing gas/air under pressure. In such systems the gas flow generally is controlled so that it is in accordance with the demand, i.e. it is the question of demand systems. In ordinary demand valves there is commonly a direct mechanical connection between a sensor diaphragm and the valve which opens or closes the nozzle opening. Similarly to the present invention, other demand valves are based on a servo principle. This implies that the pressure energy in a portion of the gas flow is utilized to amplify the force causing opening/closing of the nozzle. The pressure variations which have to be created on the sensor diaphragm to move the nozzle opening, thereby can be significantly reduced. Traditionally, servo valves have the weakness that they are constructed in a complicated manner and that they require frequent readjustments in order to operate satisfactorily. Further, servo valves often give an unstable gas regulation as a consequence of sealing means causing friction, or regulating mechanisms giving a time delay between the movement of the pilot valve and the main valve.
According to the invention there is provided a gas regulating valve of the introductorily stated type which, according to the invention, is characterized in that the control valve brings about a controlled gas flow to the servo chamber, which entails that the main valve body is forced to move such that the seat of the control valve at all times rests sealingly against the valve body of the control valve.
The valve according to the invention does not have stability problems as a consequence of friction in sealing means, and the regulating force is very small. Further, there is a minimum time delay between the control valve and the main valve, whereby a very precise control of large gas quantities is achieved. The invention, used both as a demand valve and as a pressure reduction valve, has been found to be very advantageous. It is simple to produce, it is not very sensitive to pressure variations, and it has a very good capacity.
The invention will be further described below with reference to the drawings, wherein
FIG. 1 shows a cross-section of an embodiment of a regulating valve according to the invention used on a demand valve, and
FIG. 2 shows a somewhat enlarged sectional view of the regulating valve.
The illustrated demand valve consists of an outer casing 7 having a sensing diaphragm 8 which, through a lever 9 and an operating means 4, influences the gas regulating valve which is fixedly mounted to the casing 7.
The regulating valve comprises a housing 1 having an inlet chamber I and an outlet chamber II, a hollow main valve body 2 cooperating with a seat 3 separating the inlet chamber I from the outlet chamber II, a piston 12 separating the outlet chamber II from the servo chamber III of the valve, and a control valve comprising a valve body 5 and a seat 6, and which is arranged to be opened and closed by the main valve body 2. The seat 6 of the control valve is arranged in a channel 15 extending axially through the main valve body 2 and connecting the inlet chamber I with the servo chamber III, and the control valve body 5 is connected to the operating means 4 of the demand valve through said channel. The control valve regulates the gas flow between the inlet chamber and the servo chamber through the channel 15. When the valve body of the control valve is displaced, a gas flow is supplied to the servo chamber, and this causes a corresponding displacement of the main valve body.
As shown in the drawings, one side surface of the servo chamber III is constituted by one side s
REFERENCES:
patent: 591013 (1897-10-01), Schreidt
patent: 873324 (1907-12-01), Michaels
patent: 2925824 (1960-02-01), Rockwell
patent: 3945393 (1976-03-01), Teatini
patent: 4834086 (1989-05-01), Garofalo
Miller V.
Ottestad Breathing System A/S
Weiland Robert N.
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