# US 4,395,995 A · Circulating fuel heating system for internal combustion engines > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,395,995 A - Document ID: US4395995A - Status: Granted - Kind: A - Application number: 06/284,527 - Filed: 1981-07-17 - Granted: 1983-08-02 - Earliest claimed: 1981-03-09 - Inventors: Theron H. Crain - Web page: https://patentgrep.com/patent/US4395995A ## CPC - F02D 33/006: {depending on engine operating conditions, e.g. start, stop or ambient conditions} - F02M 31/16: Other apparatus for heating fuel - F02M 37/0047: {Layout or arrangement of systems for feeding fuel (fuel injection apparatus characterised by their conduits and venting means F02M55/00; fuel injection apparatus having a common rail F02M63/0225; arrangement of fuel conduits of low pressure fuel injection apparatus F02M69/462)} - F02B 3/06: with compression ignition (compression ignition engines using air or gas for blowing fuel into compressed air in cylinder F02B13/02) - F02D 2200/0606: Fuel temperature - F02M 37/0035: {Thermo sensitive valves} - Y02T 10/12: Improving ICE efficiencies - F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W) - F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF - F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract An improved circulating fuel heating system for internal combustion engines of both gas and diesel types. The system is sizeable through staged heat exchanger components to provide the necessary fuel heating for various engine sizes and fuel consumption rates in order to maintain the temperature of the fuel entering the carburetor bowl to just above the temperature of vaporization for the fuel. The system basically comprises a plurality of staged fuel/hot water heat exchangers, a fuel controller interposed between the heat exchanger and the carburetor bowl, a hot water control valve operably connected to a temperature sensor in the controller to control the flow of hot water through the heat exchanger and hence, the temperature of the fuel entering the controller, and a second fresh air fuel/exhaust manifold heat exchanger constructed as a part of the controller to satisfy initial heating requirements for the fuel for a period after cold engine starting and for events of undersizing of the staged hot water heat exchanger. ## Claims ### Claim 1 A circulating fuel heating system for internal combustion engines having a carburetor, said system comprising heat exchanger means for raising the temperature of the fuel to beyond its vaporization temperature, pump means for delivering fuel to said heat exchanger means, a fluid heat source carried by the engine and operably connected to the heat exchanger means, a fluid heat flow control valve operably connected to the heat exchanger for selectively controlling the flow of heated fluid from the fluid heat source through the heat exchanger means, a fuel controller means operably connected between the heat exchanger means and the carburetor, return control means operably connected between the controller means and the pump means for the routing of unused fuel back to said pump means, a first temperature sensor carried by the controller means and operably connected to the fluid heat flow control valve for regulating the flow of fluid from the fluid heat source through the heat exchanger means to maintain the temperature of the fuel in the controller within a predetermined range above its temperature of vaporization. ### Claim 2 (depends on 1) A fuel heating system as set forth in claim 1 wherein said fluid heat source comprises a hot water outlet port, a hot water line and return line, said hot water line and return line being operably connected to said heat exchanger means through said fluid heat flow control valve. ### Claim 3 (depends on 1) A fuel heating system as set forth in claim 1 wherein said heat exchanger means comprises at least one heat exchanger element made of thermoconductive material providing conduction heating of said fuel from said fluid heat source. ### Claim 4 (depends on 3) A fuel heating system as set forth in claim 3 and including a plurality of heat exchanger elements in cascade arrangement. ### Claim 5 (depends on 1) A fuel heating system as set forth in claim 1 wherein said pump means comprises a pair of parallel fuel pumps, at least one said pump being electrically operated. ### Claim 6 (depends on 1) A fuel heating system as set forth in claim 1 wherein said fuel controller means comprises a fuel chamber disposed in the proximity of the carburetor and having a first outlet operably connected to the carburetor and a second outlet operably connected to said return control means, said return control means comprising a metering valve for the control of fuel flow therethrough. ### Claim 7 (depends on 6) A fuel heating system as set forth in claim 6 wherein said fuel controller means includes a pressure buffer chamber having a closed upper end, the lower end thereof being operably connected to the top of said fuel chamber. ### Claim 8 (depends on 6) A fuel heating system as set forth in claim 6 wherein said fuel flow controller means comprises second fuel heat exchanger means disposed between said fuel chamber and the carburetor, a second heat source operably connected to said second fuel heat exchanger means for selectively heating the fuel between said fuel chamber and entry of the fuel into the carburetor. ### Claim 9 (depends on 8) A fuel heating system as set forth in claim 8 wherein said second heat source comprises a fresh air exhaust manifold heat exchanger for extracting heat from the exhaust manifold, and said second fuel heat exchanger means comprising a hot air chamber disposed between the fuel chamber and the carburetor, said hot air chamber being operably connected to the fresh air exhaust manifold heat exchanger, a vaccum valve operably connected to said hot air chamber for drawing the hot fresh air from the exhaust manifold heat exchanger through said hot air chamber, a second temperature sensor carried by said fuel chamber and operably connected to the said vacuum valve for controlling the flow of hot air through said hot air chamber. ### Claim 10 (depends on 1) A fuel heating system as set forth in claim 1 and including at least one fuel line enlargement chamber operably connected to said pump means for retarding the back flow of fuel upstream of said pump means. ### Claim 11 (depends on 6) A fuel heating system as set forth in claim 6 wherein said fuel flow controller means comprises a second fuel heat exchanger means disposed adjacent to said fuel chamber and made as an integral part thereof, said second fuel heat exchanger comprising a longitudinal groove provided adjacent said fuel chamber and in intimate contact therewith, an elongated pipe segment made of heat conductive material disposed within said groove, a second heat source operably connected to said second fuel heat exchanger means for selectively heating the fuel in said fuel chamber prior to the entry of said fuel into the carburetor. ### Claim 12 (depends on 11) A fuel heating system as set forth in claim 11 wherein said second heat source comprises a fresh air exhaust manifold heat exchanger for extracting heat from the exhaust manifold, a vacuum valve operably connected to said elongated pipe segment for drawing hot fresh air from the exhaust manifold heat exchanger through said pipe segment, a second temperature sensor carried by said fuel chamber and operably connected to said vacuum valve for controlling the flow of hot air through said pipe segment. ### Claim 13 (depends on 1) A fuel heating system as set forth in claim 1 and including a restricted fuel bypass line operably connected to the heat exchanger means for bypassing a small portion of said fuel around the heat exchanger for preventing vapor lock during erratic engine operation conditions.