# US 7,607,422 B2 · Methods of flexible fuel engine conversions > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,607,422 B2 - Document ID: US7607422B2 - Status: Granted - Kind: B2 - Application number: 11/954,105 - Filed: 2007-12-11 - Published: 2008-04-17 - Granted: 2009-10-27 - Earliest claimed: 2005-04-25 - Inventors: Grant B Carlson; Karl Heise - Web page: https://patentgrep.com/patent/US7607422B2 ## CPC - F02P 5/1527: {with means allowing burning of two or more fuels, e.g. super or normal, premium or regular} - F02D 19/066: {Retrofit of secondary fuel supply systems; Conversion of engines to operate on multiple fuels} - F02D 19/087: {with determination of densities, viscosities, composition, concentration or mixture ratios of fuels} - F02D 41/0025: {Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures} - F02P 5/1518: {using two or more central computing units, e.g. interpolation} - F02D 41/266: {the computer being backed-up or assisted by another circuit, e.g. analogue} - F02D 2200/0611: Fuel type, fuel composition or fuel quality - F02D 2400/11: After-sales modification devices designed to be used to modify an engine afterwards - Y02T 10/30: Use of alternative fuels, e.g. biofuels - Y02T 10/40: Engine management systems - F02P: IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES ({anti-pollution means for internal-combustion engines F02B17/00}; specially adapted for rotary-piston or oscillating-piston engines F02B53/12; {ignition of gas turbine plants F02C7/26; ignition of jet propulsion plants F02K9/95; starting of combustion engines F02N9/00}; ignition of combustion apparatus in general, glowing plugs F23Q; measuring of physical variables in general G01; controlling in general G05; data processing in general G06; electrical components in general see Section H; {ignition coils H01F38/12}; sparking plugs H01T13/00) - 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) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract Methods and apparatus are disclosed for converting and optimizing the fuel system of an internal combustion engine in a pre-existing (used) vehicle to be fuel flexible and thus to operate on a mixture of fuels (like ethanol and gasoline) from a single fuel tank. The conversion includes adding a fuel composition sensor installed in the fuel line and/or adding an exhaust gas oxygen sensor installed in the engine's exhaust in addition to adding an electronic control unit with at least one fuel injector driver circuit for controlling an output signal to at least one fuel injector for controlling the air to fuel ratio of the engine. The electronic control unit can control both engine ignition timing and the air to fuel ratio of the engine based upon the composition of fuel mixture in the fuel tank. The electronic control unit can also control other aspects of engine operation like intake manifold boost for those engines that have turbo or superchargers. ## Claims ### Claim 1 An apparatus converting an OEM type engine having an OEM type of fuel system and exhaust system using an OEM type recommended fuel fed to the engine from an OEM type fuel tank, the apparatus comprising: varying proportions of an alternate fuel being mixed with the OEM recommended fuel in the OEM type fuel tank to form a varying fuel mixture; a sensor added to detect the proportional amount of alternative fuel in the fuel mixture being fed to the OEM fuel system from the OEM fuel tank, the sensor being selected from a group consisting of: a) an exhaust gas O2 sensor; and b) a fuel composition sensor; a fuel injector driver circuit added to the OEM type engine to control an output signal to a fuel injector; an electronic control unit added to the OEM type engine to control the fuel injector driver circuit, the electronic control unit being arranged to receive an input signal from the sensor; and the electronic control unit being arranged to change the output signal from the fuel injector driver circuit to the fuel injector to vary the amount of the fuel being metered into the OEM type engine to control the engine's operating condition to maintain a correct air-to-fuel ratio needed for proper combustion of the fuel mixture fed from the OEM fuel tank. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the exhaust gas O2 sensor is selected from the group consisting of a wideband oxygen sensor and a narrowband oxygen sensor. ### Claim 3 (depends on 1) The apparatus of claim 1 wherein the fuel injector is an additional fuel injector added to the OEM type fuel system and is controlled by the electronic control unit. ### Claim 4 (depends on 1) The apparatus of claim 1 wherein more than one fuel injector is added to the OEM type engine and controlled by the electronic control unit. ### Claim 5 (depends on 1) The apparatus of claim 1 wherein both the exhaust gas O2 sensor and the fuel composition sensor are used together. ### Claim 6 (depends on 1) The apparatus of claim 1 wherein both the exhaust gas O2 sensor and the fuel composition sensor are arranged to simultaneously detect the proportional amount of alternate fuel being fed into the OEM engine. ### Claim 7 (depends on 1) The apparatus of claim 1 wherein the OEM fuel system contains an OEM type carburetor or OEM type throttle body and the fuel injector is placed in communication with the carburetor or throttle body to provide additional fuel from the OEM type fuel tank as commanded by the electronic control unit. ### Claim 8 (depends on 7) The apparatus of claim 7 wherein the OEM type throttle body or carburetor is configured to flow air only, and the added fuel injector provides all the fuel that is needed to control the engine's operating condition regardless of the composition of the fuel mixture in the OEM type fuel tank. ### Claim 9 (depends on 1) The apparatus of claim 1 wherein the OEM fuel system includes an OEM type engine control module, and the electronic control unit receives as an input fuel injector drive signals from the OEM type engine control module and then modifies those drive signals based on a signal from the sensor in order to control the operating condition of the OEM type engine. ### Claim 10 (depends on 1) The apparatus of claim 1 further including an ignition control circuit for controlling ignition timing of the engine based upon the proportional amount of alternative fuel in the fuel mixture being fed to the OEM fuel system from the OEM fuel tank. ### Claim 11 (depends on 10) The apparatus according to claim 10 wherein an ignition timing signal is received by the ignition control circuit from either an OEM type engine control module or an OEM type engine's spark generating device. ### Claim 12 (depends on 11) The apparatus according to claim 11 wherein the ignition timing signal received by the ignition control circuit is then delayed or advanced by the ignition control circuit before being sent to the spark generating device. ### Claim 13 (depends on 12) The apparatus of claim 12 wherein the ignition control circuit is located in the electronic control unit. ### Claim 14 (depends on 12) The apparatus of claim 12 wherein the ignition control circuit uses input from the selected sensor to determine the octane of the mixed fuel and to then control engine timing. ### Claim 15 (depends on 12) The apparatus of claim 12 wherein the ignition control circuit is adapted to receive input from a user to set an amount of timing delay or advance for different operating conditions of the OEM type engine. ### Claim 16 (depends on 1) The apparatus of claim 1 wherein the fuel injector is an OEM type fuel injector that is part of the stock OEM fuel system and is controlled by the electronic control unit. ### Claim 17 (depends on 1) The apparatus of claim 1 wherein the electronic control unit can receive input from a user to set a capacity value for the fuel injector being controlled by the electronic control unit. ### Claim 18 (depends on 1) The apparatus of claim 1 wherein the apparatus uses more than one independent fuel injector drive circuit to individually control more than one fuel injector used to increase the dynamic range of the fuel delivery of the OEM type engine. ### Claim 19 (depends on 1) The apparatus of claim 1 wherein the electronic control unit uses input from a fuel composition sensor to determine the octane rating of the fuel mixture in the OEM type fuel tank and then uses that octane determination to control the amount of intake manifold pressure boost of the OEM type engine by a turbocharger or by a supercharger. ### Claim 20 (depends on 19) The apparatus of claim 19 wherein the electronic control unit controls the amount of pressure boost in the OEM type engine's intake manifold by controlling a waste gate in a turbocharger system. ### Claim 21 (depends on 1) The apparatus of claim 1 wherein the electronic control unit maintains proper fuel line pressure and controls fuel line flow capacity via control of OEM type electric fuel pump. ### Claim 22 A method of converting OEM type engine using an OEM type recommended fuel fed to the engine from an OEM type fuel tank, the method comprising: varying proportions of an alternate fuel being mixed with the OEM recommended fuel in the OEM type fuel tank to form a varying fuel mixture; adding a sensor to detect the proportional amount of alternative fuel in the fuel mixture being fed to the OEM fuel system to the OEM fuel tank selected from a group consisting of: a) an exhaust gas O2 sensor; and b) a fuel composition sensor; adding a fuel injector driver circuit to control an output signal to a fuel injector; providing an electronic control unit controlling the fuel injector driver circuit and receiving an input signal from the sensor; and arranging the electronic control unit to change the output signal from the fuel injector driver circuit to the fuel injector to vary the amount of the fuel being metered into the OEM type engine to control the engine's operating condition to maintain a correct air-to-fuel ratio needed for proper combustion of the mixed fuel fed from the OEM fuel tank. ### Claim 23 (depends on 22) The method of claim 22 including optimizing the flexible fuel conversion of an OEM type turbocharged engine by controlling via the electronic control unit and a fuel composition sensor, the OEM engine's operating condition, and by controlling intake manifold boost pressure, fuel metering and ignition timing to improve engine efficiency and performance regardless of the composition of the fuel mixture. ### Claim 24 (depends on 22) The method of claim 22 including optimizing the flexible fuel conversion of an OEM type supercharged engine by controlling via the electronic control unit and a fuel composition sensor, the OEM engine's operating condition, and by controlling intake manifold boost pressure, fuel metering and ignition timing in order to improve engine efficiency and performance regardless of the composition of the fuel mixture. ### Claim 25 (depends on 22) The method of claim 22 including replacing or upgrading parts of the OEM fuel system that are not compatible with the alternate fuel or that limit the engine's performance or peak efficiency on the alternate fuel. ### Claim 26 (depends on 22) The method of claim 22 including controlling an OEM fuel pump to maintain proper fuel pressure and flow while operating on the alternate fuel. ### Claim 27 (depends on 22) The method of claim 22 including determining octane rating of the mixed fuel in the OEM type fuel tank based upon output of the sensor and then adjusting timing of the OEM type engine via an ignition control circuit to avoid engine knock and improve engine efficiency and performance regardless of the composition of the fuel.