US3585841A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Self-calibrating pressure ratio measurement system
Assignee: Bendix Corp
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Filing: 1970-05-22
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Granted: 1971-06-22
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Expires: 1990-05-22
Abstract
Abstract A strain gauge pressure-sensing means senses a first pressure and provides an excitation voltage inversely corresponding to the first pressure. The excitation voltage is applied through a pair of potentiometers to a pair of strain gauge pressure sensors for excitation of the sensors which alternately sense the first pressure and a second pressure through a pressure-switching means. The pressure sensors provide output signals corresponding to the sensed pressure and the excitation so that the signals therefrom correspond to the ratio of the first and second pressures when the second pressure is sensed and correspond to unity when the first pressure is sensed. A switching circuit connects the signal from the sensor sensing the first pressure to an amplifier which compares the signal with a unity reference signal and amplifiers any difference. The amplifier energizes a motor which drives a wiper of the potentiometer associated with the sensor sensing the first pressure to vary the excitation thereto so that the output therefrom corresponds to unity, whereby each sensor is alternately compensated for unstable characteristics and calibrated with the pressure sensing means.
Inventors
- 👤 William E Brandau
- 👤 Anthony E Napp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 16:26
CPC Classifications
G; G01; G01L; G01L15/00; G01L9/00; G01L9/02; G01L9/04; G01L9/045
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
197 words
A pressure ration measurement device for providing an output corresponding to the ratio of first and second pressures, comprising: master pressure sensing means for sensing the first pressure and providing an excitation signal inversely corresponding to the first pressure; a pair of pressure sensors of a type that have an output providing a signal corresponding to a sensed pressure an an excitation signal, said sensorS connected to the master pressure sensing means for receiving the excitation signal therefrom; pressure-switching means for alternately switching the first and second pressures between the pair of pressure sensors so that the sensors alternately sense the first and second pressures, whereby the sensor sensing the first pressure provides a signal corresponding to unity and the sensor sensing the second pressure provides a signal corresponding to the ratio of the first and second pressures; a reference voltage source providing a voltage corresponding to unity; and calibration means for comparing the signal from the sensor sensing the first pressure with the unity reference voltage and for varying the sensor excitation to compensate for any difference between the unity reference voltage and the signal, whereby the sensors are alternately calibrated with the master pressure sensor.
Claim 2
Dependent Claim
197 words
A pressure ration measurement device for providing an output corresponding to the ratio of first and second pressures, comprising: master pressure sensing means for sensing the first pressure and providing an excitation signal inversely corresponding to the first pressure; a pair of pressure sensors of a type that have an output providing a signal corresponding to a sensed pressure an an excitation signal, said sensorS connected to the master pressure sensing means for receiving the excitation signal therefrom; pressure-switching means for alternately switching the first and second pressures between the pair of pressure sensors so that the sensors alternately sense the first and second pressures, whereby the sensor sensing the first pressure provides a signal corresponding to unity and the sensor sensing the second pressure provides a signal corresponding to the ratio of the first and second pressures; a reference voltage source providing a voltage corresponding to unity; and calibration means for comparing the signal from the sensor sensing the first pressure with the unity reference voltage and for varying the sensor excitation to compensate for any difference between the unity reference voltage and the signal, whereby the sensors are alternately calibrated with the master pressure sensor.
Claim 3
Dependent Claim
36 words
A device as described in claim 1, additionally comprising switch means for connecting to the sensor sensing the second pressure and for providing a continuous output corresponding to the ratio of the first and second pressures.
Claim 4
Dependent Claim
30 words
A device as described in claim 2, additionally comprising a source providing a timing signal said pressure switching means and switching means being actuated in response to the timing signal.
Claim 5
Dependent Claim
22 words
A device as described in claim 1, wherein each pressure sensor and the master pressure sensing means include strain gauge pressure sensors.
Claim 6
Dependent Claim
91 words
A device as described in claim 1, wherein the master pressure sensing means comprises: pressure-sensing means responsive to the excitation signal and the first pressure for providing an electrical output corresponding thereto; and means for providing the excitation signal said means having an input connected to the reference voltage source for receiving the reference voltage and an input connected to the last-mentioned pressure-sensing means for receiving the electrical output therefrom said means responsive to the received signals to vary the excitation signal so that it inversely corresponds to the first pressure.
Claim 7
Dependent Claim
142 words
A device as described in claim 1, wherein the calibration means comprises; a pair of potentiometers connecting the master pressure sensing means to each of the pair of pressure sensors; a pair of motors arranged to drive the potentiometers; a pair of amplifiers for providing excitation signals to the motors, each amplifier having a first input connected to the reference voltage source and a second input; and switching means for connecting the second input to the output of the associated pressure sensor when the sensor is sensing the first pressure and for connecting the second input to the first input when the sensor is sensing the second pressure, whereby the amplifiers sense any difference between the sensor outputs and the reference voltage and in response thereto excite the motors to drive the potentiometers until the sensor output equals the unit reference voltage.
Claim 8
Dependent Claim
43 words
A device as described in claim 6, wherein said switch means also connects the output of the sensor sensing the second pressure to an output terminal so that a continuous output is provided corresponding to the ratio of the first and second pressures.
Claim 9
Dependent Claim
30 words
A device as described in claim 7, additionally comprising a source providing a timing signal said pressure switching means and switching means being actuated in response to the timing signal.
References Cited (Backward Citations)
US3104540A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-06-21 | 1974-12-21 | 1975-06-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-21 | 1978-12-21 | 1979-06-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-21 | 1982-12-21 | 1983-06-22 | $7700.00 | Window Closed / Lapsed |