APPARATUS FOR CONTROLLING ENVIRONMENTAL CONDITIONS, SUITABLE FOR USE UNDERWATER

• US 3,556,098 A
• Filed: 12/04/1968
• Issued: 01/19/1971
• Est. Priority Date: 12/04/1968
• Status: Expired due to Term

• Current Assignee: John W. Kanwisher, Walter A. Starch
• Original Assignee: John W. Kanwisher, Walter A. Starch
• Inventors: Kanwisher, John W., Starch, Walter A.
• Application Number:
  US04/780,961
• Time in Patent Office: 776 Days
• US Class Current: 128/202.22
• CPC Class Codes: A61M 16/0051 with alarm devices
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 16/10 Preparation of respiratory gases or vapours
• CPC Class Codes: A61M 16/1015 using a gas flush valve, e.g. oxygen flush valve
• CPC Class Codes: A61M 16/12 by mixing different gases
• CPC Class Codes: A61M 16/202 electrically actuated
• CPC Class Codes: A61M 16/208 Non-controlled one-way valves, e.g. exhalation, check, pop-off non-rebreathing valves
• CPC Class Codes: A61M 16/22 Carbon dioxide-absorbing devices ; Other means for removing carbon dioxidecartridges with absorbing substances for respiratory apparatus A62B19/00
• CPC Class Codes: A61M 2016/1025 the O2 concentration
• CPC Class Codes: A61M 2202/025 Helium
• CPC Class Codes: B63C 11/24 in closed circulation
• CPC Class Codes: Y10T 137/2509 By optical or chemical property

Abstract

The subject of the invention described in the following specification relates to the problem of maintaining a safely breathable oxygen-containing atmosphere. Thus, the invention is especially useable under abnormal environmental conditions where it is necessary to provide and control an atmosphere suitable therein. The disclosed illustrative embodiment is a selfcontained closed circuit-type underwater breathing apparatus for diver use. A plurality of oxygen sensor cells, preferably at least three, each thermistor temperature compensated, are exposed to the gas stream in the system, each providing a current resulting in voltage drop across the thermistor, directly related to oxygen concentration which voltages then are amplified and electronically processed to operate oxygen supply means, which is a solenoid valve, whereby oxygen partial pressure is constantly maintained within a predetermined range. In the processing, the amplified voltages are electronically mathematically averaged and processed to deliver a single control signal to the solenoid. The system is adjusted at atmospheric pressure to provide one-half atmosphere oxygen partial pressure at a selected voltage level, e.g. about 2.4 volts average amplified cell voltage. As the quantity of oxygen thereafter varies in use by the diver, the average voltage varies linearly and the solenoid acts responsively thereto. Each amplified cell output is also connected into an alarm circuitry so that should any cell (or two or more) provide a voltage corresponding to oxygen partial pressure below or above a predetermined safe oxygen range, an audible alarm is sounded as a warning that something is wrong in the system. Separate visual oxygen partial pressure indicators are connected into the circuitry at the electronic amplification stages so that the diver may observe the individual indications provided by each of the sensor cells and, thereupon, determine the emergency remedial steps necessary to be taken. In the exemplary three-sensor system, the probability of simultaneous or close timewise malfunctioning of more than one sensor or its directly associated circuitry is extremely low - so low that in practical use it may reasonably be taken as zero. Consequently, the diver, while of course, recognizing the remote possibility of such a plural maloccurrence, may, and in practice will, presume any two similar partial pressure indicators correctly to reflect the actual internal conditions of the system - unless, of course, his own understanding of the particular situation might rarely permit a different conclusion. Contemplating most importantly such a single maloccurrence (thereupon resulting in an alarm sounding and indications from the meters that one of the voltage inputs is spurious) the design of the system, involving as it does the aspect of solenoid valve control by the average voltage, is such that the electronic circuitry responds to limit, or stabilize, the effect of the spurious voltage input upon the average voltage. This is accomplished via transistor clipping circuitry and an associated regulated pg,3 voltage source. Thereupon a nonvarying voltage, which is not outside the selected range for acceptable and safe oxygen partial pressure, constantly appears in the average voltage. Accordingly, the effective average voltage is then within the safe range aNd continues effectively to operate and to maintain a suitable oxygen partial pressure as long as the signals from the remaining cells are developed and delivered and they themselves are a correct measure of the oxygen partial pressure actually in the system. The system contemplates also an adjunctive, separate and exteriorly attachable sensor-indicator means by which the system may be further verified whereby the security of the diver is much enhanced. The system includes inert gas supply means which may be manually or automatically operated for supplying the remaining gas volume and pressure necessary for breathing underwater. By these and other means, the safety for the diver is enormously increased and the purpose of his dive can be accomplished under a minimum of constraint.

Claims

1. A closed circuit underwater breathing apparatus which maintains the concentration of oxygen within a zone at or near a predetermined desired level, which comprises at least three (3) separate means for sensing the instant oxygen concentration existing in said zone and for producing separate signals normally proportional thereto, means for receiving said three signals and delivering thereupon a combined signal output normally similarly proportional to said concentration;

oxygen supply control means responsive to said output and operable to effect adjustment of said oxygen concentration in said zone when said output deviates from a value corresponding to said desired level;

said device also including means for controlling the effect of either of said separate signals upon said output in the event of an occurrence leading to a signal failure, whereby said output continues to be compatible with the operational characteristics of said oxygen supply control means and said concentration is maintained substantially as normal notwithstanding such occurrence.

2. separate means for amplifying each of said signals;

3. A device as claimed in claim 1 wherein metering means is provided for each of said proportional signals.

4. means for combining said amplified signals and delivering thereupon an average output proportional to said oxygen concentration, said output controlling the input of oxygen via a solenoid operated valve and associated circuitry such that said valve is closed at a predetermined oxygen concentration falling within a preselected physiologically tolerable oxygen concentration range and opens to deliver oxygen when said output represents an oxygen concentration below the said predetermined concentration;

5. A device as claimed in claim 1 wherein warning means is provided to give notice of signal failure.

6. audible alarm means connected in the electronic circuitry of said device, said alarm being adapted to sound upon the limiting of any signal value by said clipping circuitry;

7. A device as claimed in claim 4 wherein warning means is provided to give notice of signal failure.

8. diluent gas supply means connecting into sAid breathing circuit.