US4709575A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fluidic oxygen sensor monitor
Assignee: Northrop Grumman Guidance and Electronics Co Inc
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Filing: 1986-05-05
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Granted: 1987-12-01
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Expires: 2006-05-05
Abstract
Abstract A fluidic bridge for determining the partial pressure of a gas has a positive pressure inlet for a reference gas and a sample gas and an ambient pressure outlet. The reference gas and the sample gas pass through a capillary passage and an orifice passage, and the pressure differential between the outlet of the reference capillary passage and the outlet of the sample capillary passage is a function of the density of the gas. A pressure ratio regulator is used to equalize the pressure of the reference gas and the sample gas applied to the inlets of the capillary passages. The length of the capillary passages and the flow characteristics of the orifice passages are adjustable to allow the bridge to be properly calibrated after being assembled.
Inventors
- 👤 William P. Myers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:36
CPC Classifications
G; G01; G01N; G01N7/00
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
101 words
A fluidic sensor for determining the partial pressure of oxygen in a gas comprising: a positive pressure inlet for a reference gas and a positive pressure inlet for a sample gas, a capillary passage for the reference gas and a capillary passage for the sample gas, an orifice passage for the reference gas and an orifice passage for the sample gas, an outlet for the fluidic sensor at ambient pressure, and means coupled to the outlets of the capillary passages for detecting a pressure differential between the outlet of the reference capillary passage and the outlet of the sample capillary passage.
Claim 2
Dependent Claim
101 words
A fluidic sensor for determining the partial pressure of oxygen in a gas comprising: a positive pressure inlet for a reference gas and a positive pressure inlet for a sample gas, a capillary passage for the reference gas and a capillary passage for the sample gas, an orifice passage for the reference gas and an orifice passage for the sample gas, an outlet for the fluidic sensor at ambient pressure, and means coupled to the outlets of the capillary passages for detecting a pressure differential between the outlet of the reference capillary passage and the outlet of the sample capillary passage.
Claim 3
Dependent Claim
29 words
The fluidic sensor of claim 1 further comprising: means for equalizing the pressure of the reference gas and the sample gas applied to the inlets of the capillary passages.
Claim 4
Dependent Claim
26 words
The fluidic sensor of claim 2 wherein inlet pressure regulators control the pressure of the reference gas and the sample gas applied to the fluidic sensor.
Claim 5
Dependent Claim
36 words
The fluidic sensor of claim 2 wherein means are provided for varying the capillary length of the adjustable capillaries in order to match the linear resistance of the capillary to the nonlinear resistance of the orifice.
Claim 6
Dependent Claim
42 words
The fluidic sensor of claim 4 wherein the means for varying comprises an elongated needle positioned in a bore of the capillary body and wherein the position of the needle within the bore may be selectively varied to vary the capillary length.
Claim 7
Dependent Claim
43 words
The fluidic sensor of claim 5 wherein the eleongated needle is dimensioned for a slip fit within said bore, and the capillary passages are formed between the sides of the bore and flats which are ground onto the surface of the elongated needle.
Claim 8
Dependent Claim
16 words
The fluidic sensor of claim 2 wherein the flow characteristics of the orifice passages are adjustable.
Claim 9
Dependent Claim
31 words
The fluidic sensor of claim 6 wherein the orifice passages comprise: an orifice through a flexible disc, and means for flexing said disc to alter the flow characteristics of said orifice.
Claim 10
Dependent Claim
32 words
The fluidic sensor of claim 2 wherein means are provided for coupling the reference gas to both adjustable capillaries in the fluidic sensor in order to test the operation of the sensor.
Claim 11
Dependent Claim
37 words
The fluidic sensor of claim 2 further comprising: a pressure ratio regulator, and a common pressure chamber in the pressure ratio regulator comprising the means for equalizing the pressure of the reference gas and the sample gas.
Claim 12
Dependent Claim
40 words
The fluidic sensor of claim 3 further comprising: an absolute pressure regulator, vent means for venting a regulator chamber of the absolute pressure regulator to ambient pressure, and feedback passages for coupling the regulator chamber to the inlet pressure regulators.
Claim 13
Dependent Claim
41 words
The fluidic sensor of claim 11 further comprising: aneroid means for controlling the vent means, whereby the regulator chamber is vented to ambient pressure below a preselected altitude, and the regulator chamber is sealed from ambient pressure above said preselected altitude.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-11-30 | 1991-06-01 | 1991-12-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-11-30 | 1995-06-01 | 1995-12-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-11-30 | 1999-06-01 | 1999-12-01 | $7700.00 | Window Closed / Lapsed |