Motorola Corporation

Engelhard Corporation

Continental Automotive Systems Corporation

Adam Moya

Chowdary Ramesh Koripella

Neil J Adams

Daniel A Young

Gerald Stephen Koermer

Linda Hratko

Craig R Markyvech

Jeffrey D Naber

Patrick W Blosser

Edward Balko

Jie Xue

Adam Miller

Jeff Naber

Neil Adams

Craig Markyvech

Chowdary R Koripella

Jeffrey Naber

A differential calorimetric gas sensor (10) which includes a sensing element (12) having a catalytic layer (14) disposed on a multi-layered substrate (26). Catalytic layer (14) includes an active catalyst region (14a) which oxidizes total combustibles within an exhaust gas stream and a reference catalyst region (14b) which oxidizes selective combustibles within the exhaust gas stream. An electrochemical oxygen source (18) is disposed on an opposite side of multi-layer substrate (26) from sensing element (12). An oxygen sensor cell (170) may be incorporated into electrochemical oxygen source (18). The multi-layered substrate (26) includes a plurality of overlaying insulating layers in which an intermediate layer (60) and a bottom layer (64) support primary heaters (58, 62), and in which another intermediate layer (52) supports compensation heaters (50a, 50b). The primary heaters (58, 62) function to maintain sensor (10) at a substantially constant temperature, while the compensation heaters (50a, 50b) function to restore temperature deviations determined by temperature-sensitive elements (46a, 46b) located on an inner layer (48) overlaying the compensation heaters (50a, 50b) resulting from the catalytic reactions taking place at the surfaces (34a, 34b) of the catalyst regions (14a, 14b). The control circuitry (300) operates to control the primary heater (58, 62) and the compensation heaters (50a, 50b), as well as to minimize the response variations of the temperature-sensitive elements (46a, 46b).

Exhaust gas sensor

A calorimetric hydrocarbon gas sensor (10) includes an electrochemical oxygen pump (18), a sensing element (12), and a multi-layered substrate (26) separating the sensing element (12) from the electrochemical oxygen pump (18). The multi-layered substrate (26) includes a plurality of overlying insulating layers, in which at least one intermediate layer (60) supports a first primary heater (58), and in which another intermediate layer (52) supports a temperature compensation heaters (50a, 50b). The primary heater (58) functions to maintain the calorimetric hydrocarbon gas sensor (10) at a constant, elevated temperature, while the active compensation heater (50a) functions to maintain substantially equal temperatures as determined by the thermometers (46a, 46b) located on an intermediate layer (48) overlying the compensation heaters (50a, 50b). Control circuitry is integrated with power measurement circuitry to measure differences in the heat produced by the compensation heater (50a) and the thermometer (46a) in an active region (100), and the heat produced by the compensation heater (50b) and the thermometer (46b) in a reference region (102).

Calorimetric hydrocarbon gas sensor

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Albuquerque, NM, United States of America

Adam Moya