US3794070A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Precision reference pressure supply system
Assignee: Honeywell Inc
•
Filing: 1972-03-20
•
Granted: 1974-02-26
•
Expires: 1992-03-20
Abstract
Abstract A closed loop, selectively variable precision pressure reference system for testing pneumatic apparatus comprising all solid state digital control of a precision valve for establishing and maintaining the selected or desired reference pressure as a ratio between a positive pressure and a vacuum, the pressure ratio being sensed by a precision pressure sensor of the vibrating diaphragm type. The desired reference pressure is expressed as a binary word and the output of the pressure sensor is converted to a binary word, these two words being digitally compared and the difference therebetween being converted to an analog signal for adjusting the valve thereby closing the loop to maintain the selected pressure. The system is also capable of providing a precision pressure rate reference. The system automatically compensates for the inherent non-linear characteristics of the pressure sensor over its range of operation.
Inventors
- 👤 C Klem
- 👤 R Riall
- 👤 R Wallace
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:20
CPC Classifications
G; G05; G05D; G05D16/00; G05D16/20; G05D16/2006; G05D16/2013; G05D16/2026; G05D16/2046; G05D16/2053; Y; Y10; Y10T; Y10T137/00; Y10T137/7722; Y10T137/7758; Y10T137/7761; Y10T137/8593; Y10T137/86389
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
207 words
A reference pneumatic pressure supply system, the combination comprising a reference pressure chamber, positionable valve means coupled with said chamber and a source of high pneumatic pressure and a source of low pneumatic pressure and adapted to control the resultant of said pressures within said chamber, means for providing a first multi-bit digital word corresponding to a selected pneumatic pressure reference, pressure sensor means responsive to the pressure in said chamber for providing a second multi-bit-digital word corresponding to the pneumatic pressure within said chamber, means responsive to said digital words for providing a third multi-bit digital word corresponding to the difference therebetween, digital-to-analog converter means responsive to said difference word for providing an analog error signal corresponding thereto, means responsive to said analog error signal for positioning said valve means in a sense and to an amount to reduce said third digital word to zero, slew detector means responsive to the most significant bits of said third multi-bit digital word for providing a constant analog voltage output corresponding in sense to the sense of said difference word, and means for supplying said constant voltage to said valve positioning means whereby to slew the pressure existing in said reference pressure chamber rapidly toward said selected reference pressure.
Claim 2
Dependent Claim
207 words
A reference pneumatic pressure supply system, the combination comprising a reference pressure chamber, positionable valve means coupled with said chamber and a source of high pneumatic pressure and a source of low pneumatic pressure and adapted to control the resultant of said pressures within said chamber, means for providing a first multi-bit digital word corresponding to a selected pneumatic pressure reference, pressure sensor means responsive to the pressure in said chamber for providing a second multi-bit-digital word corresponding to the pneumatic pressure within said chamber, means responsive to said digital words for providing a third multi-bit digital word corresponding to the difference therebetween, digital-to-analog converter means responsive to said difference word for providing an analog error signal corresponding thereto, means responsive to said analog error signal for positioning said valve means in a sense and to an amount to reduce said third digital word to zero, slew detector means responsive to the most significant bits of said third multi-bit digital word for providing a constant analog voltage output corresponding in sense to the sense of said difference word, and means for supplying said constant voltage to said valve positioning means whereby to slew the pressure existing in said reference pressure chamber rapidly toward said selected reference pressure.
Claim 3
Dependent Claim
43 words
The reference pressure supply system as set forth in claim 1 wherein said digital-to-analog converter means is responsive only to the least significant bits of said digital difference word below the most significant bits thereof to which said slew detector means is responsive.
Claim 4
Dependent Claim
57 words
The reference pressure supply system as set forth in claim 1 wherein said valve positioning means further includes integrator means responsive to said analog error signal for maintaining said valve position as said error signal is reduced to zero, said system further including means responsive to an output of said slew detector means for clamping said integrator.
Claim 5
Dependent Claim
61 words
The reference pressure supply means as set forth in claim 3 further including, means responsive to the rate of change of the output of said slew detector for supplying a signal pulse upon the output of said slew detector going to zero and, means for supplying said signal pulse to said integrator means to rapidly increase the output of said integrator.
Claim 6
Dependent Claim
247 words
A reference pressure supply system comprising the combination of a reference pressure chamber, positionable valve means coupled with said chamber and a source of high pneumatic pressure and a source of low pneumatic pressure and adapted to control the resultant of said pressures within said chamber, means for providing a first multi-bit word corresponding to a selected pneumatic pressure reference, pressure sensor means responsive to the pressure in said chamber for pRoviding an electrical output signal having a frequency which varies as a non-linear function of said chamber pressure, converter means responsive to said sensor signal for providing a further signal having an amplitude proportional to the frequency of said sensor signal, frequency-to-digital converter means for converting said sensor frequency to a second multi-bit digital word corresponding to the pneumatic pressure within said chamber, means responsive to said first and second multi-bit digital words for providing a third multi-bit digital word corresponding to the difference therebetween, digital-to-analog converter means responsive to said difference word for providing an analog error signal corresponding thereto, means for supplying said further signal to said digital-to-analog converter means whereby to vary the amplitude of the analog output thereof as a function of said sensor frequency, and means responsive to said analog error signal for positioning said valve means in a sense and to an amount to reduce said third digital word to zero whereby to establish and maintain the resultant pressure in said reference pressure chamber in accordance with said selected pressure.
Claim 7
Dependent Claim
247 words
A reference pressure supply system comprising the combination of a reference pressure chamber, positionable valve means coupled with said chamber and a source of high pneumatic pressure and a source of low pneumatic pressure and adapted to control the resultant of said pressures within said chamber, means for providing a first multi-bit word corresponding to a selected pneumatic pressure reference, pressure sensor means responsive to the pressure in said chamber for pRoviding an electrical output signal having a frequency which varies as a non-linear function of said chamber pressure, converter means responsive to said sensor signal for providing a further signal having an amplitude proportional to the frequency of said sensor signal, frequency-to-digital converter means for converting said sensor frequency to a second multi-bit digital word corresponding to the pneumatic pressure within said chamber, means responsive to said first and second multi-bit digital words for providing a third multi-bit digital word corresponding to the difference therebetween, digital-to-analog converter means responsive to said difference word for providing an analog error signal corresponding thereto, means for supplying said further signal to said digital-to-analog converter means whereby to vary the amplitude of the analog output thereof as a function of said sensor frequency, and means responsive to said analog error signal for positioning said valve means in a sense and to an amount to reduce said third digital word to zero whereby to establish and maintain the resultant pressure in said reference pressure chamber in accordance with said selected pressure.
Claim 8
Dependent Claim
60 words
The reference pressure supply system as set forth in claim 5 wherein said valve positioning means further includes variable gain integrator means responsive to said analog error signal for maintaining said valve position as said error signal is reduced to zero, and means responsive to said further signal proportional to sensor frequency for controlling the gain of said integration means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-25 | 1977-08-27 | 1978-02-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-25 | 1981-08-27 | 1982-02-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-25 | 1985-08-27 | 1986-02-26 | $7700.00 | Window Closed / Lapsed |