Fuel heater system and self-regulating heater therefor

Claim 1

A self-regulating heater device for a system for supplying an air-fuel mixture to an internal combustion engine comprising; a thermally conducting metal radiator member having a first heat-receiving side and having a second, opposite side for transferring heat to at least one component of the air-fuel mixture, means for mounting the radiator member in the fuel supply system to dispose the second, heat-transferring side of the member to heat at least said one component of the air-fuel mixture, and at least one self-regulating electrical resistance heater element of a ceramic material of a positive temperature coefficient of resistivity having oppositely facing first and second sides, the element being disposed with the first side in facing relation to a first portion of the heat-receiving side of the radiator member for transferring heat from the first side of the heater element to the radiator member, characterized in that: a plurality of said ceramic heater elements are disposed with said first sides thereof in facing relation to respective first portions of the heat-receiving side of the metal radiator member; a thermally conducting metal heat-transfer member has a plurality of first portions mounted in facing relation to the second sides of the respective heater elements receiving heat from the second element sides and has second portions disposed in spaced facing relation to corresponding second portions of the heat-receiving side of the radiator member transferring heat received from the second sides of the heater elements to the radiator member; resilient conductive means are disposed between each of the heater element sides and a respective one of the metal members and the metal members are secured together in electrically insulated relation to each other holding the resilient conductive means in resilient electrical engagement with the respective heater element sides; a thermally conducting filler is disposed in the space between said facing second portions of the metal members to facilitate transfer of heat from the heat-transfer member to the radiator member, the filler comprising a silicone based electrically insulating material; and said first portions of the metal radiator and heat-transfer members are recessed, and said resilient conductive means comprise wave springs which are disposed in the respective recessed portions of the metal members positioning the springs in resilient electrical engagement with the heater sides and with the metal members to electrically connect the heater element sides to the respective members, the thermally conducting electrically insulating filler means being disposed in the recessed portions of the metal members to facilitate heat transfer from the heater elements to the metal members.