US4881183A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for emission testing
Assignee: Snap On Inc
•
Filing: 1988-03-25
•
Granted: 1989-11-14
•
Expires: 2008-03-25
Abstract
Abstract A computerized emissions tester determines concentrations of HC, CO, and CO2 in exhaust emissions. An IR test bench assembly develops an analog voltage representative of the concentration of a particular gas in a sample gas of known concentration. Data related to calibration pressure, voltage offset and voltage gain are stored in non-volatile memory EEPROM. Algorithms relating voltage and concentration of the particular gases are included in software. The pressure of an exhaust emission is compared with the calibration pressure data in memory and a correction is applied to the tester output. The data relating to the voltage offset and gain factor are also used to compensate the tester output.
Inventors
- 👤 David E. Groe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:31
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/25; G01N21/31; G01N21/35; G01N21/3504; G01N2201/00; G01N2201/12; G01N2201/121; G01N2201/1218; G01N2201/127; G01N2201/12746; G01N2201/12753
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
192 words
An emissions tester comprising: means for calibrating said tester with a test sample having a known concentration of a particular gas; means for storing pressure data for said test sample in a non volatile memory; means for developing an analog voltage signal representative of the concentration of said particular gas in an exhaust emission; an analog to digital converter for converting said analog voltage signal into a digital value, the range of said analog to digital converter being greater than the span of said analog voltage; means for offsetting said analog voltage to substantially center it within the range of said analog to digital converter; means for storing data, related to the amount of voltage offset, in a non-volatile memory; means for correcting said analog voltage signal by said stored offset data; means for sensing the pressure of said exhaust emission; means for compensating said analog voltage signal based upon the difference in the sensed pressure and the stored pressure; means for storing a gain factor in a non-volatile memory for relating said calibration voltage to a desired voltage; and means for adjusting said analog voltage signal by said stored gain factor.
Claim 2
Dependent Claim
192 words
An emissions tester comprising: means for calibrating said tester with a test sample having a known concentration of a particular gas; means for storing pressure data for said test sample in a non volatile memory; means for developing an analog voltage signal representative of the concentration of said particular gas in an exhaust emission; an analog to digital converter for converting said analog voltage signal into a digital value, the range of said analog to digital converter being greater than the span of said analog voltage; means for offsetting said analog voltage to substantially center it within the range of said analog to digital converter; means for storing data, related to the amount of voltage offset, in a non-volatile memory; means for correcting said analog voltage signal by said stored offset data; means for sensing the pressure of said exhaust emission; means for compensating said analog voltage signal based upon the difference in the sensed pressure and the stored pressure; means for storing a gain factor in a non-volatile memory for relating said calibration voltage to a desired voltage; and means for adjusting said analog voltage signal by said stored gain factor.
Claim 3
Dependent Claim
12 words
The emission tester of claim 1 wherein said non-volatile memories are EEPROMs.
References Cited (Backward Citations)
US4093871A
Cited
US4159523A
Cited
US4254469A
Cited
US4348732A
Cited
US4314344A
Cited
US4357668A
Cited
US4328546A
Cited
US4390956A
Cited
US4467435A
Cited
US4454852A
Cited
US4454853A
Cited
US4672566A
Cited
US4638443A
Cited
US4576035A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-11-13 | 1993-05-15 | 1993-11-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-11-13 | 1997-05-15 | 1997-11-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-11-13 | 2001-05-15 | 2001-11-14 | $7700.00 | Window Closed / Lapsed |