Adjustable pressure transducer with digital signal output

• US 3,908,461 A
• Filed: 06/20/1974
• Issued: 09/30/1975
• Est. Priority Date: 06/20/1974
• Status: Expired due to Term

• Current Assignee: Oliver S. Turpen
• Original Assignee: Oliver S. Turpen
• Inventors: Turpen, Oliver S.
• Primary Examiner(s): Woodiel, Donald O.
• Application Number:
  US05/481,082
• Time in Patent Office: 467 Days
• Field of Search: 73/398AR,410,4.5R 338/41,201,39,40,42
• US Class Current: 73/725
• CPC Class Codes: G01L 9/0035 using variations in ohmic resistance

Abstract

A pressure transducer assembly for indicating ambient pressure over a predetermined differential pressure range having a minimum and a maximum and operable over a wide range of absolute pressures. A housing having an interior in fluid communication with ambient pressure surrounds a digital signal generator which is protected from ingressing contaminants. The digital signal generator includes a translatable electrical contact member secured to the working end of a surrounding electrically conductive bellows secured at the remaining end to the housing and a stationary multi-resistor assembly having a staggered pair of rows of spaced contact pads and miniature resistors coupled between selected pads in opposite rows to provide a series resistance network whose resistance depends on the position of the contact element, the pads and resistors being supported on an insulated substrate. The multi-resistor assembly is supported by a conductive rod which is translatable in opposite directions along the axis of the housing by a simple adjustment mechanism so that the fixed differential pressure operating range may be shifted over a wide range of absolute pressures. A plurality of transducers are mounted in a sheathed telephone feed cable at regularly spaced positions therealong, with each transducer being electrically connected to a different pair of subscriber conductors so that the pressure at any given location along the feed cable can be determined by applying a test voltage across individual subscriber conductor pairs at a remote location and noting the resistance.

Claims

1. A pressure transducer assembly for indicating ambient pressure over a predetermined differential pressure range having a minimum and a maximum and operable over a wide range of absolute pressures, said assembly comprising:

a housing having an interior;

means for communicating ambient pressure to said interior; and

means supported in said housing interior for generating discrete signals over said differential pressure range each representative of a different value of said ambient pressure, said generating means including means defining a protective enclosure for preventing contamination thereof;

said generating means including a multi-resistor assembly and a contact element, one of said multi-resistor assembly and said contact element being translatable relative to the other in response to changes in said ambient pressure;

said multi-resistor assembly including an insulated substrate, a pair of spaced parallel rows of electrically conductive contact pads, the contact pads of one row being staggered relative to the contact pads in the other row, and a plurality of resistive elements connected to contact pads in said pair of rows to provide a series resistance network;

said contact element having a pair of spaced contact arms, each said arm being arranged for contact with individual pads of a different row.

2. The apparatus of claim 1 wherein said communicating means comprises a porous member carried by said housing.

3. The apparatus of claim 2 wherein said porous member is integral with said housing.

4. The apparatus of claim 1 wherein said multi-resistor assembly is stationary and said contact member is translatable.

5. The apparatus of claim 1 wherein said resistive elements are arranged to provide a logarithmic resistance scale.

6. The apparatus of claim 1 wherein said protective enclosure includes an outer bellows member having a first end secured to said housing and a second end translatably received in said housing interior, said contact element being secured to said second end.

7. The apparatus of claim 1 further including means for adjusting the absolute value of the minimum and maximum of said differential pressure range.

8. The apparatus of claim 1 further including means for varying the relative position of said multi-resistor assembly and said contact element to establish the absolute value of the minimum and maximum of said differential pressure range.

9. The apparatus of claim 8 wherein said multi-resistor assembly is carried by a rod and wherein said adjusting meAns includes means for translating said rod along the axis of said housing.

10. A system for measuring ambient pressure at spaced locations along an enclosed volume of interest, said system comprising:

a longitudinally extending enclosure defining said volume;

a plurality of pairs of electrical conductors extending along said volume; and

a plurality of pressure transducers each positioned along said volume at different predetermined spaced locations, each said pressure transducer having a pair of electrical signal leads coupled to a different one of said plurality of pairs of electrical conductors;

each said pressure transducer comprising a housing having an interior;

means for communicating ambient pressure to said interior; and

means coupled to said pair of electrical signal leads for generating discrete signals on said electrical signal leads over said differential pressure range, each representative of a different value of said ambient pressure, said generating means including means defining a protective enclosure for preventing contamination thereof;

said generating means including a multi-resistor assembly and a contact element, one of said multi-resistor assembly and said contact element being translatable relative to the other in response to changes in said ambient prdssure;

said multi-resistor assembly including an insulated substrate, a pair of spaced parallel rows of electrically conductive contact pads, the contact pads of one row being staggered relative to the contact pads in the other row, and a plurality of resistive elements connected to contact pads in said pair of rows to provide a series resistance network, said pads and said resistive elements being supported on said substrate;

said contact element having a pair of spaced contact arms, each said arm being arranged for contact with individual pads of a different row.

11. The apparatus of claim 10 wherein said multi-resistor assembly is stationary and said contact member is translatable.

12. The system of claim 10 wherein said resistive elements are arranged to provide a logarithmic resistance scale.

13. The system of claim 10 wherein said protective enclosure includes an outer bellows member having a first end secured to said housing and a second end translatably received in said housing interior, said contact element being secured to said second end.

14. The system of claim 10 wherein each said pressure transducer includes means for adjusting the absolute value of the minimum and maximum of said differential pressure range.

15. The system of claim 10 wherein each said pressure transducer includes means for varying the relative position of said multi-resistor assembly and said contact element to establish the absolute value of the minimum and maximum of said differential pressure range.

16. The system of claim 15 wherein said multi-resistor assembly is carried by a rod and wherein said adjusting means includes means for translating said rod along the axis of said housing.

17. The system of claim 10 wherein said longitudinally extending enclosure comprises a telephone feed cable and said plurality of pairs of electrical conductors comprise individual subscriber conductors.