OXYGEN PARTIAL PRESSURE SENSOR

• US 3,805,590 A
• Filed: 03/09/1973
• Issued: 04/23/1974
• Est. Priority Date: 03/09/1973
• Status: Expired due to Term

• Current Assignee: Carl G. Ringwall, William L. Keltz
• Original Assignee: Carl G. Ringwall, William L. Keltz
• Inventors: Ringwall, Carl G., Keltz, William L.
• Primary Examiner(s): Queisser, Richard C.
• Assistant Examiner(s): Kreitman, Stephen A.
• Application Number:
  US05/340,610
• Time in Patent Office: 410 Days
• Field of Search: 73/23,24 128/14R,142
• US Class Current: 73/24.01
• CPC Class Codes: B63C 11/24 in closed circulation
• CPC Class Codes: G01N 2291/012 Phase angle
• CPC Class Codes: G01N 2291/0212 Binary gases
• CPC Class Codes: G01N 29/024 by measuring propagation velocity or propagation time of acoustic waves
• CPC Class Codes: G01N 29/22 Details , e.g. general constructional or apparatus details
• CPC Class Codes: G01N 29/323 compensating for pressure or tension variations
• CPC Class Codes: G01N 29/34 Generating the ultrasonic, sonic or infrasonic waves , e.g. electronic circuits specially adapted therefor
• CPC Class Codes: G01N 29/36 Detecting the response signal , e.g. electronic circuits specially adapted therefor

Abstract

A pressure programmed, piezoelectric sensor for the partial pressure of oxygen in a helium-oxygen breathing gas mixture is described, together with associated electronic circuitry for use in a diving apparatus. The sensor utilizes acoustic signal phase shift to generate electrical signals by which the apparatus maintains oxygen partial pressure within the required limits for breathing at various water depths.

Claims

1. A sensor device for use in determining oxYgen partial pressure in mixed gas breathing apparatus, said device comprising:

a housing defining a central cavity, said housing comprising side walls and oppositely disposed end walls;

an opening defined in one of said end walls for communication of mixed gas between said cavity and the exterior of said housing;

an expansible bellows disposed in said housing having one end mounted on the other of said end walls;

a shaft mounted on the other end of said bellows for axial movement by said bellows in response to changes in total pressure of said mixed gas;

a plurality of multi-legged spring elements mounted on said shaft for movement therewithi, said elements each having a plurality of radially extending legs;

a plurality of adjustable stop members extending from said other end wall, each of said stop members being engageable by one of said legs of said spring elements at predetermined axial positions of said shaft;

a first piezoelectric transducer element mounted on said housing;

a second piezoelectric transducer element mounted on said shaft in spaced relation to said first piezoelectric transducer element and movable with said axial movement of said shaft toward and away from said first piezoelectric transducer element;

one of said piezoelectric transducer elements being responsive to first electrical signals having a characteristic frequency to transmit acoustic energy into said gas mix in a direction parallel to said axial movement of said shaft;

the other of said piezoelectric transducer elements being adapted to receive said acoustic energy and to produce second electrical signals of said characteristic frequency and having a phase relation to said first electrical signals that is a function of the positioning of said shaft and said second piezoelectric transducer element by said bellows and of said oxygen partial pressure in said mix; and

said positioning of said shaft and said second piezoelectric transducer element being a function of said total pressure and of the spring rates of said multi-legged spring elements, whereby differences from a predetermined phase relation may be taken as a measure of departure of oxygen partial pressure from the desired partial pressure for any existing total pressure within a predetermined range of total pressures.

2. A sensor device as defined in claim 1, and further characterized by:

support spring means, connected between said housing and said shaft, for confining said shaft to axial movements.

3. A sensor device as defined in claim 2, and wherein said support spring means comprises:

an outer ring portion of a first diameter engaging said housing;

an inner ring portion of a second, smaller diameter engaging said shaft; and

a plurality of resiliently flexible, serpentine leg portions interconnecting said outer and inner ring portions.

4. A sensor device as defined in claim 3, and wherein said spring elements comprise:

first, second, and third spring elements each having a central ring portion carried on said shaft and having three radially extending legs disposed equiangularly with respect to adjacent ones thereof;

said first, second, and third spring elements being disposed with respect to one another on said shaft such that the legs of each are angularly offset with respect to the legs of the others, whereby all of the legs have their ends free of interference from the others.