Heater for air-fuel mixture having heating element of positive

Abstract

A heater for an air-fuel mixture having a heating element of a positive temperature coefficient resistor comprises a pair of metallic thin cylinders of different sizes each having outward flange portions at least at one end combined with each other as a double cylinder; a plurality of positive temperature coefficient resistors arranged between said inner and outer cylinders with springs for pressing the positive temperature coefficient resistors to the inner cylinder wall; an electric insulator plate inserted between the outward flange portions of said inner cylinder and the outward flange portions of said outer cylinder; a fixing means anchoring between said outward flange portion of the outer cylinder and said outward flange portion of the inner cylinder for fixing integrally with electric insulator plate; an electrically insulating material inserted between an inner end portion of the inner cylinder and an inner end portion of the outer cylinder for spacing between said inner end portion of the inner cylinder and said inner end portion of the outer cylinder with end gaps so as to insulate said inner end portions of said inner cylinder and outer cylinder. The engine with this heater can easily start and requires no fuel-rich mixture even in cold weather. As a result, an exhaust amount of carbon monoxide and hydrocarbon in exhaust gas can be remarkably reduced and an engine having excellent acceleration ability immediately after starting can be obtained.