APPARATUS FOR MIXING GASES

• US 3,727,627 A
• Filed: 07/15/1970
• Issued: 04/17/1973
• Est. Priority Date: 07/15/1970
• Status: Expired due to Term

• Current Assignee: Forrest Morton Bird, Henry Louis Pohndorf
• Original Assignee: Forrest Morton Bird, Henry Louis Pohndorf
• Inventors: Bird, Forrest Morton, Pohndorf, Henry Louis
• Primary Examiner(s): Cline, William R.
• Application Number:
  US05/054,934
• Time in Patent Office: 1,007 Days
• Field of Search: 137/7,100,98,101,111 128/142.2,142.3,145.8
• US Class Current: 137/100
• CPC Class Codes: A61M 16/20 Valves specially adapted to medical respiratory devices
• CPC Class Codes: A61M 16/206 Capsule valves, e.g. mushroom, membrane valves
• CPC Class Codes: A61M 16/207 Membrane valves with pneumatic amplification stage, i.e. having master and slave membranes
• CPC Class Codes: B01F 23/191 characterised by the construction of the controlling means
• CPC Class Codes: Y10T 137/2521 Flow comparison or differential response

Abstract

A method and apparatus for mixing gases from separate pressurized gas circuits for use in applications such as medical respirators. The pressures of the gases in the two circuits are accurately balanced to provide an equal pressure drop across a differential mixing valve for precise control of the ratio of flow rates of the gases being mixed. In one embodiment, a double state pressure balancing mechanism is provided for increased accuracy of pressure balance.

Claims

1. Apparatus for the controlled mixing of gasses from separate pressurized gas circuits for delivery through a common flowpath, including the combination of pressure balance means to establish a substantially equal gas pressure in a downstream segment of each circuit, the pressure balance means including first control valve means controlling pressure in the downstream segment of the gas circuit and second control valve means controlling pressure in the downstream segment of the other gas circuit, valve operating means opening and closing the first valve means while conjointly closing and opening the second valve means responsive to a differential in pressure between the gasses in said downstream segments of the gas circuits to vary the pressures in said downstream segments for reducing said pressure differential to establish an equal pressure balance in said downstream segments, and mixing valve means to mix the gas from each downstream segment into said common flowpath, said mixing valve means including means forming a mixing chamber in communication with said common flowpath, means forming a pair of orifices each communicating between a respective one of said downstream segments and with said mixing chamber, means forming a pair of valve elements each adapted for movement within a respective one of said orifices to control the gas flow area thereof, and means to conjointly move said valve elements with respect to said orifices to reciprocally vary said flow areas to vary the ratio of the gas mixture.

2. Apparatus as in claim 1 in which the valve operating means includes movable wall means having opposed sides in communication with respective downstream segments of the gas circuits, and means mounting the movable wall means in operating connection with said first and second valve means for said conjoint movement thereof responsive to an imbalance in gas pressures acting on said opposite sides of said wall means.

3. Apparatus as in claim 1 in which the first and second valve means each include a valve opening in a respective gas circuit together with a valve provided with a pair of valve closure elements movable to open and close a respective opening, and said valve operating means including means to conjointly move said valve closure elements to and from respective openings.

4. Apparatus for the controlled mixing of gasses from separate pressurized gas circuits for delivery through a common flow path, including the combination of pressure balance means to balance the gas pressure in a segment of each circuit, the pressure balance means including first control valve means in one gas circuit, second control valve means in the other gas circuit, first valve operating means opening and closing the first valve means while conjointly closing and opening the second valve means responsive to a differential in pressure between the gasses downstream of the first and second valve means to establish an equal pressure balance in said downstream gas pressures, third control valve means in said one gas circuit, fourth control valve means in said other gas circuit, each of the third and fourth valve means located downstream of the first valve operating means, a second valve operating means opening and closing the third control valve means while conjointly closing and opening the fourth control valve means, the second valve operating means operating responsive to a differential in pressure between the gasses downstream of the third and fourth valve means to establish an equal pressure balance in said last mentioned downstream gas pressures, and mixing valve means to mix the gas from eacH circuit downstream of the third and fourth control valve means into said common flow path.

5. Apparatus for the control mixing of gasses from separate pressurized gas circuits for delivery through a common flow path, including the combination of pressure balance means to balance the gas pressure in a segment of each circuit, the pressure balance means including first control valve means in one gas circuit and second control valve means in the other gas circuit, valve operating means opening and closing the first valve means while conjointly closing and opening the second valve means responsive to a differential in pressure between the gasses downstream of the first and second valve means to establish an equal pressure balance in said downstream gas pressures, the valve operating means including movable wall means comprising a flexible diaphragm separating the gas circuits downstream of said control valve means, means mounting the movable wall means in operating connection with said first and second valve means for said conjoint movement thereof responsive to an imbalance in pressure acting on opposite sides of said wall means, said mounting means comprising a valve stem mounted for movement with the diaphragm and with said first and second valve means formed at either end of said valve stem, and mixing valve means to mix the gas from each circuit downstream of the control valve means into said common flow path.

6. Apparatus for the controlled mixing of gasses from separate pressurized gas circuits for delivery through a common flow path, including the combination of pressure balance means to balance the gas pressure in a segment of each circuit, the pressure balance means including first control valve means in one gas circuit and second control valve means in the other gas circuit, valve operating means opening and closing the first valve means while conjointly closing and opening the second valve means responsive to a differential in pressure between the gasses downstream of the first and second valve means to establish an equal pressure balance in said downstream gas pressures, said first and second valve means each comprising an orifice in a respective gas circuit together with a valve element movable to open and close a respective orifice under influence of said valve operating means, said orifices being spaced apart to define opposed valve seats having adjacent downstream passages, said valve elements being mounted for movement in the downstream passages for reciprocal opening and closing of the flow area through said orifices, and mixing valve means to mix the gas from each circuit downstream of the control valve means into said common flow path.

7. Apparatus as in claim 6 in which said downstream passages define a cavity, and said valve operating means comprises flexible wall means dividing said cavity into separate chambers each communicating with a respective downstream passage together with means mounting said valve elements for conjoint movement with said wall.

8. Apparatus for the controlled mixing of gasses from separate pressurized gas circuits for delivery through a common flow path, including the combination of pressure balance means to balance the gas pressure in a segment of each circuit, the pressure balance means including first control valve means in one gas circuit and second control valve means in the other gas circuit, valve operating means opening and closing the first valve means while conjointly closing and opening the second valve means responsive to a differential in pressure between the gasses downstream of the first and second valve means to establish an equal pressure balance in said downstream gas pressures, and mixing valve means to mix the gas from each circuit downstream of the control valve means into said common flow path, said mixing valve means comprising first and second metering valve means each controlling the flow of gas in a respective circuit downstream of said pressure balance means, each of said metering valve meaNs being mounted for conjoint movement to reciprocally open and close flow through its associated circuit to establish a preselected ratio of flow between the two circuits, and means combining said gas flows downstream of said metering valves for combined flow into said common flow path.

9. Apparatus as in claim 8 in which said first and second metering valves each comprise an orifice in a respective gas circuit downstream of its associated first or second control valve means together with a valve element movable to control flow through said orifice, and means to selectively move said valve element of each of the metering valves in conjoint adjusting movement to increase gas flow through one of said orifices while reciprocally decreasing flow through the other of said orifices for establishing a preselected ratio of flow between the two gases.

10. Apparatus as in claim 9 in which said orifices are spaced apart to define opposed valve seats, said valve elements are spaced apart and mounted for movement between said valve seats, and further including means to selectively adjust the position of said valve elements between said valve seats to establish said preselected ratio of flows.