Air-fuel charge heater and humidifier

Claim 1

In combination with a combustion engine including an air and fuel charge forming device defining an air and fuel passage therethrough, an induction passage inlet end for receiving an air and fuel charge from said charge forming device and an engine exhaust system, a liquid vaporizing attachment, said attachment defining an intermediate passage extending therethrough including inlet and outlet ends communicated with the outlet end of said air and fuel passage and said induction passage inlet end, respectively, and an intermediate portion extending between said inlet and outlet ends of said intermediate passage, said intermediate portion including selectively operable electrical resistance heating means disposed therein for heating the fluid flow therethrough, and selectively operable valve means for variably throttling the flow of fluid through said intermediate portion, means defining a bypass passage including inlet and outlet ends opening into said inlet and outlet ends of said intermediate passage and bypassing the intermediate portion of said intermediate passage, and exhaust gas heated heat exchange means operatively associated with said bypass passage intermediate the inlet and outlet ends thereof for heating the flow of fluid therethrough; whereby selective operation of said valve means enables heating of an air and fuel charge during initial engine operation by said heating means in said intermediate portion of said intermediate passage, subsequent heating of said charge by said heat exchange means in said bypass passage after initial engine warm-up and deactivation of said heating means, and subsequent prevention of overheating of said charge after engine warm up and during periods of higher ambient temperature by decreasing and increasing the portion of said charge flowing through said bypass passage and intermediate portion of said intermediate passage, respectively.