Abstract: An electrode structure for air-fuel ratio detecting, including a grate-like or perforated metal plate coated with a layer of alumina which is coated with a layer of platinum which is in electrical contact with a solid electrolyte which is formed for contacting both exhaust gases and the ambient atmosphere, so that when the platinum is exposed to engine exhaust gases catalytic action of the platinum lowers the oxygen partial pressure at the electrolyte surface to its equilibrium concentration causing an abrupt change in electromotive force detectible between a positive electrode in electrical contact with the solid electrolyte, and the grate electrode.

Abstract: Apparatus for feeding water to the air/fuel mixture passage between the air/fuel mixing device and combustion chamber of an internal combustion engine including a main conduit for supplying water to the mixture passage, a valve member for opening and closing the conduit, the valve member being biased into the closed position, a diaphragm communicating on one side directly to the mixture passage for actuating the valve member to an open position and on the other side through a pressure delay chamber with the mixture passage, wherein the conduit is opened only by a relatively abrupt increase in pressure in the mixture passage, and the closing is delayed until the pressure equalizes across the diaphragm. Water may be supplied to the conduit directly by a pump, or by a pressure differential or by means of a reservoir having access to a water supply.