Engelhard Corporation

Motorola Corporation

Edward Balko

Gerald Stephen Koermer

Gerald Steven Koermer

Chowdary Ramesh Koripella

Linda Hratko

Jeffrey D Naber

Patrick W Blosser

Neil J Adams

Daniel A Young

Jie Xue

Adam Moya

Imelda L Castillo

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 catalytic structure may be in the form of a ceramic support member having disposed on it a catalytic material which is a fired coating (124a-1, 124a-2) of a catalytic ink. The catalytic ink contains a liquid vehicle, at least one metal resinate compound and fine particles of a refractory metal oxide having dispersed thereon a catalytically effective amount of a catalytic metal component such as platinum or palladium or combinations of two or more catalytic metal components. The resulting catalytic structure may be employed as a catalytic gas sensor (24, 124) and further may include at least one conductor member (130, 132) which provides both temperature sensing of the fired catalytic coating (124a-1, 124a-2) to ascertain the degree of reaction taking place at the surface thereof, and heating of the support member to heat the fired catalytic coating to a temperature high enough to promote the catalytic reaction. The catalytic structure may be prepared by applying to a substrate a coating of a catalytic ink or paste and firing the applied coating.

Catalytic structure

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Middletown, NJ, United States of America

Edward Balko