METHOD FOR DETECTING THE PERCENTAGE OF ETHANOL IN FUEL, FUEL SUPPLY SYSTEM OF AN ENGINE, FLEX-FUEL VEHICLE, AND, COMPUTER-READABLE NON-TRANSIENTIAL MEDIUM

Abstract

A method (100) of detecting a percentage of ethanol in fuel used by an engine (26) is provided. The method includes obtaining a heater temperature at a first time t1 at which a slope of the heater temperature as a function of time reaches a predetermined threshold value indicative of fuel boiling; obtaining the heater temperature at a subsequent time t2 at which the slope of the heater temperature approaches a value of the slope prior to the time t1 and which is greater than the predetermined threshold value; and determining the percentage of ethanol in the fuel as a function of the first time t1 and a calculated temperature difference ∆T between the heater temperature at time t2 and the heater temperature at the first time t1. A fuel delivery system (20) that detects a percentage of ethanol in fuel by the method, and a flexible fuel vehicle including the fuel delivery system, are also provided.

Description

/ 21 METHOD FOR DETECTING THE PERCENTAGE OF ETHANOL IN FUEL, FUEL SUPPLY SYSTEM OF AN ENGINE, FLEX-FUEL VEHICLE, AND, COMPUTER-READABLE NON-TRANSIENTIAL MEDIUM CROSS-REFERENCE TO RELATED ORDERS

[001] This application claims the benefit of U.S. Application No. 18 / 119.395, filed on March 9, 2023, the description of which is incorporated by reference in its entirety. FIELD OF THE INVENTION

[002] The description generally refers to the detection of ethanol in engine fuel and, more specifically, to the determination of the ethanol content of the fuel with a heated component of an automotive engine fuel supply system. FUNDAMENTALS OF THE INVENTION

[003] Flexible-fuel vehicles (FFVs, which may also be called flex-fuel, dual-fuel, total flex, flexifuel, hi-flex, or simply flex) are vehicles that have an internal combustion engine capable of operating using conventional vehicle fuel (e.g., unleaded gasoline) and an alternative fuel, such as ethanol or methanol, which are stored in the same fuel tank as the vehicle. The most common type of flexible-fuel vehicle has an engine that can run on gasoline, gasoline-ethanol blends (e.g., E10, E20, E85), and / or pure ethanol (E100). E85, also known as flex fuel, is a gasoline-ethanol blend that includes up to 85% by volume of anhydrous ethanol and, in practice, may contain between 51% and 85% anhydrous ethanol depending on the geographic region and seasonal temperatures.Other common gasoline and ethanol blends include E10 (containing a maximum of 10% anhydrous ethanol), E20 (containing a maximum of 20% anhydrous ethanol), E25 (containing a maximum of 25% anhydrous ethanol), and E70. Petition 870250101555, dated 06 / 11 / 2025, page 6 / 43 / 21 (containing a maximum of 70% anhydrous ethanol) and E75 (containing a maximum of 75% anhydrous ethanol). Pure ethanol (E100) does not contain gasoline and is 100% hydrated ethanol, which contains on average 5.3% by volume of water and the remainder ethanol. Due to its inherent water content, pure ethanol is sometimes called E95.

[004] The type / combination of fuel used in a flex-fuel vehicle may vary based on user preference and the availability of the various combinations described above. For example, a user may fill the fuel tank of a flex-fuel vehicle with gasoline and later, when the tank is empty and / or needs refueling, may fill the tank with E85 fuel. The user may therefore freely switch between gasoline (which in its pure form contains no ethanol, but as it is currently sold at gas pumps in the United States, may contain up to 10% ethanol) and E85, which is more than half ethanol.As shown by the example in Figure 1, when refueling a tank where the fuel has been switched from a low-ethanol blend to a high-ethanol blend, it takes approximately 400 seconds for the engine to be idling to purge the old (original) fuel from the vehicle's fuel delivery system lines and for the vehicle's onboard control module to complete learning the ethanol content of the new fuel. Therefore, for some flex-fuel vehicles, it is recommended to drive the vehicle for a minimum of 4 miles (approximately 11 kilometers) after refueling to ensure the vehicle's computer has sufficient time to learn the ethanol content present in the fuel tank and make any necessary operational adjustments.If the flex-fuel vehicle does not have enough time to learn the ethanol content when there is a change between the use of gasoline and the use of ethanol or ethanol combinations, the user... Petition 870250101555, dated 06 / 11 / 2025, page 7 / 43 / 21, may encounter engine ignition problems on the next cold start after refueling. Therefore, this period after a refueling event, in which there is an alternation between the use of gasoline and ethanol / ethanol combinations, is a weak point in the ethanol learning process conducted by the vehicle's computer system. Particularly, in a spark-ignition engine fueled by gasoline, ignition of the fuel / air mixture occurs easily, except at extremely low temperatures (i.e., below -40°C), due to the relatively low flash point of gasoline. (The term "flash point" of a fuel is defined in this document as the lowest temperature at which the fuel can form a flammable mixture in air).However, in a spark-ignition engine fueled by alcohol-based fuels, such as ethanol (E100) or ethanol-gasoline blends (e.g., E85) having a much higher flash point, ignition of the fuel / air charge may not occur in colder weather conditions. For example, ethanol has a flash point of around 12.8°C. Thus, starting a spark-ignition engine fueled with ethanol can be difficult or impossible in low ambient temperature conditions, common seasonally in many parts of the world, and can be compounded by the fact that the engine computer does not recognize a change in fuel type.

[005] Conventionally, the ethanol content of fuel stored in a vehicle's fuel tank is detected and measured using an ethanol sensor located in the fuel line or by the oxygen (O2) sensor located in the engine's exhaust system. Ethanol content can also be measured indirectly in other ways, such as by measuring the electrical capacitance of the fuel. However, given the significant time delay for a vehicle to learn the ethanol content of the fuel by conventional methods (e.g., the oxygen sensor measures the mixture after combustion) and the potential undesirable effects of this time delay, there Petition 870250101555, dated 06 / 11 / 2025, page 8 / 43 / 21, a need for an alternative method to determine the ethanol content of fuel used in flex-fuel vehicles. BRIEF SUMMARY

[006] A method is provided for detecting the percentage of ethanol in the fuel used by an engine. The method includes initiating a heating cycle in a component of an engine fuel supply system, the component including a heater. The method further includes monitoring the heater temperature as a function of time, the heater being operated during the heating cycle. The method further includes obtaining the heater temperature at a first time t1, where the slope of the heater temperature as a function of time reaches a predetermined threshold value indicative of fuel boiling. The method further includes obtaining the heater temperature at a subsequent time t2 where the slope of the heater temperature approaches a value of the slope prior to time t1 and is greater than the predetermined threshold value indicative of fuel boiling.The method also includes calculating a difference ΔT between the heater temperature at time t2 and the heater temperature at the first time t1. The method also includes determining the percentage of ethanol in the fuel as a function of the calculated temperature difference ΔT and the first time t1.

[007] In specific modes, the warm-up cycle is initiated before the engine is started.

[008] In specific modes, the heating cycle is initiated after a refueling event.

[009] In specific embodiments, the component is a heated fuel injector.

[0010] In specific embodiments, the heater heats a heated fuel injector body. Petition 870250101555, dated 06 / 11 / 2025, page 9 / 43 / 21

[0011] A method is also provided for detecting the percentage of ethanol in the fuel used to operate a flex-fuel vehicle engine. The method includes initiating a heating cycle in a heated fuel injector of the engine, the heated fuel injector including a heater that is operated during the heating cycle. The method further includes monitoring the heater temperature of the heated fuel injector as a function of time. The method further includes obtaining the heater temperature at a first time t1, where the slope of the heater temperature as a function of time reaches a predetermined threshold value indicative of fuel boiling. The method further includes obtaining the heater temperature at a subsequent time t2 where the slope of the heater temperature approaches a value of the slope prior to time t1 and is greater than the predetermined threshold value indicative of fuel boiling.The method further includes calculating a difference ΔT between the heater temperature at time t2 and the heater temperature at the first time t1. The method further includes determining the percentage of ethanol in the fuel as a function of the calculated temperature difference ΔT and the first time t1 in which there was a change in slope.

[0012] In specific embodiments, the heating cycle includes heating a heated fuel injector body over a period of time.

[0013] In specific configurations, the heating cycle is initiated after fuel is added to a fuel tank of the flex-fuel vehicle.

[0014] In specific models, the warm-up cycle is initiated before the engine is started.

[0015] In specific sports, the warm-up cycle lasts between 5 and 10 seconds. Petition 870250101555, dated 06 / 11 / 2025, p. 10 / 43 / 21

[0016] In specific modalities, the percentage of ethanol is determined by the following equation (I): % of ethanol in fuel = C + ati — β(ΔT).

[0017] In particular modalities, C is 49.95±2.50, α is 5.22±0.26 and β is 2.8319±0.1416.

[0018] In specific embodiments, the numerical values ​​of the formula are determined based on an empirical linear regression using experimental data points obtained from known concentrations of ethanol in the fuel.

[0019] In specific applications, the margin of error for the determined percentage of ethanol in the fuel is ±15%.

[0020] In specific embodiments, the steps of the method are performed by a control module of the fuel heater of the flex-fuel vehicle.

[0021] A fuel supply system for an engine is also provided. The fuel supply system includes a heated fuel injector, including a heater and a body that is heated by the heater. The system also includes a fuel tank that stores fuel and a fuel module that supplies fuel from the tank to the heated fuel injector. A fuel heater control module controls the heater of the heated fuel injector. The fuel heater control module detects a percentage of ethanol in the fuel used to operate the engine by the method described in this document.

[0022] A flex-fuel vehicle is also provided. The flex-fuel vehicle includes an engine and a fuel supply system that supplies fuel to the engine. The fuel supply system includes a heated fuel injector, including a heater that heats a body. The fuel supply system Petition 870250101555, dated 06 / 11 / 2025, page 11 / 43 / 21 fuel additionally includes a fuel heater control module that controls the heated fuel injector heater. The fuel heater control module detects a percentage of ethanol in the fuel used to operate the engine by the method described in this document.

[0023] Also provided is a non-transient, computer-readable medium that stores a program that causes a controller to execute the method of detecting a percentage of ethanol in the fuel used to operate a flex-fuel vehicle engine. DESCRIPTION OF THE DRAWINGS

[0024] Several advantages and aspects of this description can be understood in view of the following detailed description when considered in connection with the attached drawings, in which: Figure 1 is a graph of the percentage of ethanol in the fuel at a fuel injector of an engine after refueling the fuel tank as a function of the engine's idle time; Figure 2 is a schematic view of an engine's fuel supply system; Figure 3 is a perspective view of a heated fuel injector for use with some embodiments of the description; Figure 4 is a cutaway view of part of the heated fuel injector of Figure 3; Figure 5 is a flow diagram of a method for detecting the percentage of ethanol in the fuel used by an engine according to some embodiments of the description; Figure 6 is a graphical illustration of heat transfer through a heater surface to the fuel as a function of superheating; Petition 870250101555, dated 06 / 11 / 2025, page 12 / 43 / 21 Figure 7 is a graph of heater temperature as a function of time for various types of ethanol fuel; Figure 8 is a graph of a heating cycle of a heated fuel injector according to some embodiments of the description; Figure 9 is a scatter plot of ΔT at various known ethanol contents in the fuel; Figure 10 is a fitted line graph illustrating the calculated percentage of ethanol in the fuel at various known ethanol contents in the fuel; and Figure 11 is a histogram of the calculated percentage of ethanol in the fuel at various known ethanol contents in the fuel. DETAILED DESCRIPTION OF THE INVENTION

[0025] A method is provided for detecting the percentage of ethanol in the fuel used by an engine, as well as a fuel supply system and a flexible-fuel vehicle that detects the ethanol content in the fuel according to the method. Referring to Figures 2 to 11, where equal numbers indicate corresponding parts along the various views, the method utilizes a heated component of a vehicle fuel supply system 20. By way of non-limiting example, the heated component is illustrated and generally referred to as a heated fuel injector 22. Although the heated component is illustrated as a heated fuel injector, it should be understood that the invention is not limited to application with a heated fuel injector, but may also be applied to other heated components, such as, but not limited to, a heated fuel rail.The method provides a quick and accurate detection of ethanol in the fuel used by the vehicle using an existing heated component of the fuel supply system 20, without the need to include. Petition 870250101555, dated 06 / 11 / 2025, page 13 / 43 / 21 any additional components that serve only the purpose of performing the method. In other words, the method uses only existing components of the engine's fuel supply system. The method can also be performed before the engine starts, while the engine is not running. In contrast, existing methods for detecting ethanol in fuel can only be performed with the engine running.

[0026] Going back first to Figure 2, the fuel supply system 20 includes a fuel tank 24 that stores a volume of fuel for combustion in the internal combustion engine 26 and conversion into energy. The fuel can be any type of unleaded gasoline, a gasoline-ethanol blend, or pure ethanol. A fuel module 28 including a fuel pump 30 provides a source of pressurized fuel that is pumped to the heated fuel injector 22. The heated fuel injector 22 may be located upstream of the engine cylinders 32 and may, for example, inject fuel into an air intake port 34 of the vehicle's air intake manifold 36. An evaporative emissions canister 38 retains fuel vapors present in the fuel tank 24 and, during engine operation, these vapors are purged from the canister and supplied to the air intake manifold 36 by the opening of a canister valve 40.A fuel heater control module (FHCM) 42, in connection with an engine control module (ECM) 44, controls the heating and operation of the heater fuel injector 22. The fuel heater control module 42 and the engine control module 44 are powered by a battery 46 and, through other components and sensors, including but not limited to, a pedal position sensor 48, an engine air control valve 50, a MAT / MAP sensor 52, a Hall sensor 54, a valve timing solenoid 56, an ignition coil 58, an rpm sensor 60 and a knock sensor 62, control the... Petition 870250101555, dated 06 / 11 / 2025, page 14 / 43 / 21 fuel supply and associated combustion in engine 26. The combustion products, including carbon dioxide and water, are exhausted from the engine cylinders 32 and expelled through an exhaust system 64 which includes front and rear oxygen sensors 66, 68, respectively.

[0027] As shown in detail in Figures 3 and 4, an exemplary heated fuel injector 22 has four connecting pins 70a, 70b, 70c and 70d, a fuel inlet end 72, a fuel dispensing end 74 and a housing 76 superimposed on a fuel injector body 78.Typically, the heated fuel injector 22 is attached to the engine 26, the fuel inlet end 72 is coupled to the fuel module 28, and the fuel dispensing end 74 is positioned so that fuel passing through the body 78 is dispensed by the heated fuel injector 22 to be used by the engine to operate the engine. By way of non-limiting example, the connector pins 70a and 70b may be coupled to an actuating coil within the body 78 of the heated fuel injector 22 which operates a valve also within the body 78 and usually located at the fuel dispensing end 74. Continuing with the example, if a voltage is applied to the connector pins 70a and 70b, the valve may open to allow fuel to flow from the fuel inlet end 72, through the body 78 and out of the fuel dispensing end 74.When the voltage is removed or actively forced to zero volts, the valve may close and stop or obstruct the fuel flow. By controlling the voltage applied to connector pins 70a and 70b, the heated fuel injector 22 can be operated to dispense fuel in a controllable manner.

[0028] Figure 4 illustrates a cross-sectional view of the casing 76 with the body 78 removed. A heater, such as a heating element 80 made of electrically conductive material, is arranged to heat the fuel. Petition 870250101555, dated 06 / 11 / 2025, page 15 / 43 / 21 within the body 78, so that the heated fuel can be dispensed by the heated fuel injector 22. The heating element 80 exhibits a heating resistance such that, as electric current flows through the heating element 80, heat is generated which increases the temperature of the heater and thus heats the heating element 80 and increases the temperature of the fuel in the body and at the injector tip in the injector valve. A non-limiting exemplary value of the resistance of the heating element 80 is nominally 0.3 Ohms at 20°C. When the heated fuel injector 22 is mounted, the heating element 80 is suitably thermally coupled to the body 78 to effectively heat the fuel passing through the body 78. The heating element 80 may be formed, for example, of thick-film resistive material that may be applied to the exterior of the body 78 or applied to the interior of the housing 76.Alternatively, the heating element 80 may be formed of metal foil or wire suitably arranged to heat the body of the fuel injector 78 and thus heat the fuel passing through the heated fuel injector 22. The connection points 81 and 82 on the heating element 80 may be connected to the connector pins 70c and 70d by soldering or other known methods. By way of example, the heated fuel injector may be of the type described in U.S. Patent Application Publication No. 2010 / 0078507 and U.S. Patents Nos. 7,766,254 and 9,587,604, the full contents of which are incorporated herein by reference.

[0029] The heated fuel injector 22 also includes an integral temperature sensing element or similar that is configured to determine a temperature of the injector heater element 80. In a non-limiting example, the integral temperature sensing element may be a temperature-dependent electrical device, such as a thermistor 84. The thermistor 84 generally exhibits a resistance value that corresponds to a Petition 870250101555, dated 06 / 11 / 2025, page 16 / 43 / 21 thermistor temperature of thermistor 84. The thermistor 84 may also be formed from thick-film material applied using methods similar to those used to apply thick-film material to form the heating element 80. The thermistor 84 may also be a distinct electrical component, such as a positive temperature coefficient (PTC) or negative temperature coefficient (NTC) device fixed using solder or similar means. The location of the thermistor 84 shown in Figure 4 is a non-limiting example of suitable locations. For example, the thermistor 84, when formed from thick-film material, may overlap the heating element 80, separated from the heating element 80 by a layer of electrically insulating material, and be sized to detect temperature in a substantial area of ​​the heating element 80.By way of example, one such integral temperature sensing element is shown in U.S. Patent Application Publication No. 2011 / 0276252, the full contents of which are incorporated herein by reference. In other embodiments, the integral temperature sensing element may be the injector 80 heating element itself.

[0030] The fuel heater control module 42 and the engine control module 44 individually or together constitute a controller. As such, the controller may include a microprocessor or other set of control circuits, such as an application-specific integrated circuit (ASIC), as would be evident to those skilled in the art. The controller may also include memory, including random access memory (RAM), as well as non-volatile memory, such as electrically erasable programmable read-only memory (EEPROM), masked read-only memory (ROM), or flash memory to store one or more software routines, thresholds, and captured data. One or more software routines, including the method for detecting the ethanol content of the fuel, may be executed by the microprocessor to control the Petition 870250101555, dated 06 / 11 / 2025, page 17 / 43 / 21 engine components, including the heater fuel injector 22. The controller may also include analog-to-digital (A / D) converter circuits and digital-to-analog (D / A) converter circuits to allow the converter to establish electrical communication with devices outside the controller, such as the sensors described above. The controller may also include a power supply circuit assembly.

[0031] Figure 5 illustrates a non-limiting example of a method 100 for detecting the ethanol content of the fuel used by a flexible fuel injection internal combustion engine. Method 100 utilizes the heated fuel injector 22 which is equipped with the heating element 80 which is configured to heat the fuel inside the heated fuel injector 22 and with the temperature sensor element 84 which is capable of indicating a heater temperature. The heated fuel injector 22 is controlled by the controller which is configured to execute the steps of method 100.

[0032] In step 102, a heating cycle is initiated in the heated fuel injector 22. The heating cycle involves the operation of the heating element 80 supplying an electric current to the heating element 80, which causes the heating element 80 to generate heat and, in general, increase its temperature. The heating of the heating element 80 heats the body 78 of the heated fuel injector 22, which in turn increases the temperature of the fuel in the injector body 78 adjacent to a tip portion 86. The heating cycle can be initiated at any time, but preferably after a refueling event in which the controller detects that fuel has been added to the fuel tank 24, such as by means of a fuel level sensor 31 of the fuel module 28 in the fuel tank. Alternatively or additionally, the heating cycle can be initiated before engine ignition 26, for example, shortly before engine start, for example,Petition 870250101555, dated 06 / 11 / 2025, page 18 / 43 / 21, activated by opening the driver's side door, so that the ethanol content of the fuel can be determined before ignition without delaying the start for the driver / operator, so that the engine operating parameters can be adjusted appropriately by the controller based on the determined ethanol content. As used in this document, engine start is the period of time between an initial injection or starting event until the engine speed reaches a predetermined engine speed threshold, usually an engine idle speed, typically between 600 and 1,000 revolutions per minute (RPM). Additionally, a warm-up cycle can also be initiated at any time during engine operation to periodically measure the ethanol content in the fuel.The duration of the heating cycle itself is long enough to raise the temperature of the heating element 80°C above the boiling point of at least one component of the fuel, for example, the boiling point of ethanol, which is 79°C, and for the vaporization of the fuel to begin. In some embodiments, the duration of the heating cycle is between 3 and 10 seconds. In other embodiments, the duration of the heating cycle is between 5 and 10 seconds, 3 and 7 seconds, or 5 and 7 seconds.

[0033] In step 104, during the heating cycle, the temperature of the heating element 80 of the heated fuel injector 22 is monitored as a function of time, as a function of the elapsed time of the heating cycle. The temperature of the heating element 80 can be obtained from the temperature sensor element 84 and can be temporarily recorded in the controller's memory as a function of the heating cycle time. The temperature of the heating element 80 will continue to rise until vaporization (boiling) of the fuel in the heated fuel injector begins to occur. Table 1 below shows that the specific heats of gasoline and ethanol are similar. Therefore, the phase Petition 870250101555, dated 06 / 11 / 2025, page 19 / 43 / 21. Initial heating before boiling does not easily discriminate between different fuel compositions. However, the heats of vaporization and boiling points are quite different, which is useful for distinguishing between various fuel compositions. Pure ethanol boils at 79°C and exhibits a temperature plateau during vaporization, since the thermal energy in boiling is used to vaporize the liquid instead of heating it further. On the other hand, the various components of gasoline boil in a range of 25°C to 175°C. They do not exhibit the expected vaporization plateau, as they present many tiny plateaus that give the overall appearance of continuity throughout the temperature range of interest.But fuels with significant amounts of ethanol begin to show behavioral features of pure ethanol, with the behavior of the pure substance becoming progressively more dominant as the ethanol content increases. Table 1: Comparison of the physical properties of ethanol and gasoline______ Ethanol Gasoline Heat of Evaporation kJ / kg 850 418 Density at 20°C kg / L 0.79 0.71 to 0.77 Heat Capacity J / kg-K 2440 2220 Molar Weight g / mol 46.07 114.23 Boiling Point (°C) 79 25 to 175

[0034] The temperature of the heating element 80 responds to heat transfer factors, for example, the formation and persistence of fuel vapor bubbles on the heater surface, a factor that does not affect the bulk fuel temperature. Figure 6 shows the different phases of heater transfer as a function of superheat (Theater — Tfuel) for a pure liquid.

[0035] The bulk fuel undergoes a temperature increase based on its specific heat capacity until the phase transition to vapor begins. Since vaporization is endothermic, the fuel temperature will not increase until all the fuel has vaporized. Petition 870250101555, dated 06 / 11 / 2025, page 20 / 43 / 21 Thus, in bulk fuel, a temperature increase is followed by a temperature plateau, followed by a resumption of the temperature increase. The temperature behavior of the monitored heater generally follows this pattern. Figure 7 shows the dependence of the ethanol content on the temperature profile for E20, E60, and E100 fuels. E100 is hydrated ethanol, while E20 and E60 are mixtures of ethanol and gasoline (having 20% ​​and 60% ethanol by volume, respectively). The behavior of E20 and E60 is intermediate to that of straight-distilled gasoline and pure ethanol, depending on the ethanol content. Gasoline is already a mixture of constituents with a range of boiling points. Therefore, the more gasoline and less ethanol a fuel contains, the more diffuse its “vaporization plateau” will be.

[0036] In step 106, the controller obtains, from the monitored heater element temperature, the heater temperature measured at a first time t1, at which point the slope of the heater temperature as a function of time reaches a predetermined threshold value indicative of fuel boiling (i.e., the “vaporization plateau”). It will be recognized that the slope of the temperature vs. time characteristic can alternatively be referred to as the rate of change of temperature over time, or as the derivative of temperature with respect to time. Furthermore, the change in the slope of the heater temperature as a function of time can alternatively be called the rate of change of the temperature slope over time, or as the derivative of the temperature slope with respect to time. As described above, the heater temperature increases until the point at which the first boiling occurs, at which point (first time t1) the slope of the temperature vs. time characteristic...The time period undergoes a sharp, sometimes abrupt, reduction depending on the ethanol content of the fuel. Depending on the ethanol content, in the first time period t1, the slope may inflect, changing from positive to negative, or towards a lower ethanol content (i.e., closer to pure gasoline and...). Petition 870250101555, dated 06 / 11 / 2025, page 21 / 43 / 21 direct distillation), there is an abrupt decrease in slope, so that the rate of change of slope undergoes an abrupt negative decrease. In any case, at the beginning of boiling, the slope becomes less than zero, becomes zero, or decreases to a value approaching zero, so that the slope is less than a predetermined threshold value that is close to zero, and the rate of change of the slope is negative, i.e., the slope decreases with time. Therefore, in step 106, the slope of the temperature vs. time characteristic is compared to a predetermined threshold value that is indicative of fuel boiling, the predetermined threshold value being a positive slope close to, but slightly different from, zero, a slope of zero value, or even a slope less than zero.

[0037] At the beginning of boiling, latent thermal energy is absorbed to allow the fuel to change from the liquid phase to the vapor phase. While this phase change is in progress, the fuel temperature is essentially constant, at the boiling point of the fuel being vaporized. In step 108, the controller obtains, from the monitored heater element temperature, the heater temperature measured at a subsequent time t2 at or after which the slope of the heater temperature has approached a value of the slope prior to the change in slope at time t1. The slope of the heater temperature approaching the slope prior to the slope at the first time t1 means that the slope has changed from zero or close to zero to a positive value that is close to the previous slope and that is greater than the predetermined threshold value, or that the rate of change of the slope has undergone a positive increase.The point in time t2 corresponds to a point where all the fuel is vaporized (stabilized film boiling) and there is a resumption of the temperature increase, as shown in Figure 6. Furthermore, with reference to Figure 8, an illustrative temperature vs. time curve of the heating element is shown, in which the elapsed time... Petition 870250101555, dated 06 / 11 / 2025, p. 22 / 43 18 / 21 for the temperature inflection (reference time of "break" in slope ti) is indicated by duration A, the temperature at time ti is at point B, the temperature at the subsequent time t2 is at point D, and the time elapsed from the start of vaporization until the stabilization of vaporization (time between point B and point D) is indicated by duration C. It should be understood that the first time ti is measured from the time after the heating cycle is initiated and at which an increase in the temperature of the heating element is observed until point B where there is an abrupt change in the slope of the temperature of the heating element.In other words, the temperature of the heating element may not begin to rise until a point in time slightly greater than the zero time at which the heating cycle began (for example, a value greater than zero but less than 1 second), and the time ti is the difference between the time at which the temperature at point B is obtained and the time at which the temperature of the heating element began to increase (which may be zero seconds or a time slightly greater than zero seconds). Put another way, the first time ti is duration A, which is the time elapsed between the start of the temperature increase and the temperature "inflection" at point B.

[0038] In step 110, a temperature difference (ΔT) between the heater temperature obtained at time t2 and the heater temperature obtained at the first time ti is calculated. As shown in Figure 9, there is a distinct relationship between the ethanol content of the fuel (in % by volume) and the temperature difference ΔT. Then, in step 112, the percentage of ethanol in the fuel is determined as a function of the calculated temperature difference ΔT and the first time ti at which there was a change in the slope of the heater temperature. In particular, the percentage of ethanol is determined by the following equation (I): where the constant C and the coefficients α and β are obtained by Petition 870250101555, dated 06 / 11 / 2025, page 23 / 43 / 21 linear regression of empirical data points obtained from various known ethanol contents, such as E100, E60, and E20. A fitted line graph of these data points, including confidence interval and population range limits, is shown in Figure 10. A histogram of similar data and the calculated ethanol percentage are shown in Figure 11. As is evident from the graphs, the ethanol percentage determined by the method has a high level of confidence within ±15 percentage points of the actual ethanol concentration in % volume of the fuel. For example, if the fuel is E60 (actual ethanol content being 60% by volume), the determined ethanol content will be, at most, within the range of approximately 45% to 75%. However, the ethanol content determined by the method may be within a narrower and more precise range.These results are within the same confidence interval as other ethanol learning methods, such as those based on data obtained from oxygen sensors. In one specific embodiment, the constant C is 49.95, the coefficient α is 5.22, and the coefficient β is 2.8319. However, the numerical values ​​(C, α, β) of the formula can be adjusted based on an empirical linear regression using additional and / or alternative experimental data points obtained from known ethanol concentrations in the fuel. In some embodiments, the numerical values ​​may be within a range of ±5% of the stated values, i.e., the constant C may be 49.95±2.50, the coefficient α may be 5.22±0.26, and the coefficient β may be 2.8319±0.1416.

[0039] It should be understood that the appended claims are not limited to specific compounds, compositions, or methods described in the detailed description, which may vary among specific embodiments that fall within the scope of the appended claims. With respect to any Markush groups used in this document to describe specific features or aspects of various embodiments, different, special, and / or unexpected results may be obtained from each member of the Petition 870250101555, dated 06 / 11 / 2025, page 24 / 43 / 21 respective Markush group, independently of all other Markush members. Each member of a Markush group can be considered individually and / or in combination and provides adequate support for specific modalities within the scope of the attached claims.

[0040] Furthermore, any ranges and subranges used in the description of various embodiments of the present invention, independently and collectively, fall within the scope of the appended claims and are understood as describing and encompassing all ranges, including integer and / or fractional values, even if such values ​​are not expressly written in this document. One skilled in the art will readily recognize that the enumerated ranges and subranges sufficiently describe and permit various embodiments of the present invention, and such ranges and subranges may be further delineated in relevant halves, thirds, quarters, fifths, and so forth.As just one example, a range “from 0.1 to 0.9” may be further delineated into a lower third, i.e., from 0.1 to 0.3, a middle third, i.e., from 0.4 to 0.6, and an upper third, i.e., from 0.7 to 0.9, which individually and collectively are within the scope of the appended claims and may be considered individually and / or collectively and provide adequate support for specific embodiments within the scope of the appended claims. Furthermore, with respect to language that defines or modifies a range, such as “at least,” “greater than,” “less than,” “not more than,” and the like, it should be understood that such language includes sub-ranges and / or an upper or lower limit.As another example, a range of “at least 10” inherently includes a sub-range of at least 10 to 35, a sub-range of at least 10 to 25, a sub-range of 25 to 35, and so on, and each sub-range can be considered individually and / or collectively and provides adequate support for specific embodiments within the scope of the appended claims. Finally, an individual number within a described range can be reliable and provides support. Petition 870250101555, dated 06 / 11 / 2025, page 25 / 43 / 21 suitable for specific embodiments within the scope of the appended claims. For example, a range “from 1 to 9” includes several individual whole numbers, such as 3, as well as individual numbers, including a decimal point (or fraction), such as 4.1, which can be relied upon and provide adequate support for specific embodiments within the scope of the appended claims.

[0041] The above description is of current embodiments of the invention. Various alterations and changes may be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which shall be interpreted in accordance with the principles of patent law, including the doctrine of equivalents. This description is presented for illustrative purposes and shall not be construed as an exhaustive description of all embodiments of the invention or to limit the scope of the claims to the specific elements illustrated or described in connection with such embodiments. For example, and without limitation, any individual element of the invention described may be replaced by alternative elements that provide substantially similar functionality or that otherwise provide suitable operation.This includes, for example, currently known alternative elements, such as those that may be known today by a person skilled in the art, and alternative elements that may be developed in the future, such as those that a person skilled in the art may, after development, recognize as an alternative. Furthermore, the embodiments described include a plurality of features that are described together and that can cooperatively provide a collection of benefits. The present invention is not limited to embodiments that include all such features or that provide all the stated benefits, except to the extent expressly stated in the claims made. Any reference to claim elements in the singular, for example, using the articles “a”, “an”, “the”, or “said”, should not be interpreted as limiting the element to the singular. Petition 870250101555, dated 06 / 11 / 2025, page 26 / 43

Claims

1 / 5 CLAIMS 1. Method for detecting a percentage of ethanol in fuel used by an engine (26), characterized in that the method comprises: initiating a heating cycle in a component (22) of a fuel supply system (20) of the engine (26), the component including a heater (80); monitoring the heater temperature as a function of time, the heater being operated during the heating cycle; obtaining the heater temperature at a first time t1 where a slope of the heater temperature as a function of time reaches a predetermined threshold value indicative of fuel boiling; obtaining the heater temperature at a subsequent time t2 where the slope of the heater temperature approaches a value of the slope prior to time t1 and which is greater than the predetermined threshold value indicative of fuel boiling;Calculate the difference ΔT between the heater temperature at time t2 and the heater temperature at the first time t1; and determine the percentage of ethanol in the fuel as a function of the calculated temperature difference ΔT and the first time t1.

2. Method according to claim 1, characterized in that the heating cycle is initiated: i) before engine ignition; ii) after a refueling event; or iii) both i) and ii).

3. Method according to claim 1 or 2, characterized in that the component is a heated fuel injector.

4. Method according to claim 3, characterized in that the heater heats a heated fuel injector body.

5. Method for detecting a percentage of ethanol in fuel used to operate an engine (26) of a flexible fuel vehicle Petition 870250101564, dated 06 / 11 / 2025, page 6 / 15 2 / 5 characterized in that the method comprises: initiating a heating cycle in a heated fuel injector (22) of the engine (26), the heated fuel injector including a heater (80) which is operated during the heating cycle; monitoring the heater temperature of the heated fuel injector as a function of time; obtaining the heater temperature at a first time ti where a slope of the heater temperature as a function of time reaches a predetermined threshold value indicative of fuel boiling; obtaining the heater temperature at a subsequent time t2 where the slope of the heater temperature approaches a value of the slope prior to time t1 and which is greater than the predetermined threshold value indicative of fuel boiling;Calculate the difference ΔT between the heater temperature at time t2 and the heater temperature at the first time t1; and determine the percentage of ethanol in the fuel as a function of the calculated temperature difference ΔT and the first time ti in which there was a change in slope.

6. Method according to claim 5, characterized in that the heating cycle includes heating a heated fuel injector body over a period of time.

7. Method according to claim 5 or 6, characterized in that the heating cycle is initiated: i) after adding fuel to a fuel tank of a flex-fuel vehicle; ii) before engine ignition; or iii) both i) and ii).

8. A method according to any one of claims 5 to 7, characterized in that the duration of the heating cycle is between 5 and 10 seconds.

9. Method according to any of claims 5 to Petition 870250101564, dated 06 / 11 / 2025, page 7 / 15 3 / 5 8, characterized in that the percentage of ethanol is determined by the following equation (1): % of ethanol in fuel = C + at1 - β(Δ^.

10. Method according to claim 9, characterized in that C is 49.95±2.50, α is 5.22±0.26 and β is 2.8319±0.1416.

11. Method according to claim 9, characterized in that numerical values ​​of the formula are determined based on an empirical linear regression using experimental data points obtained from known concentrations of ethanol in the fuel.

12. Method according to any one of claims 5 to 11, characterized in that the margin of error of the determined percentage of ethanol in the fuel is ±15%.

13. Method according to any one of claims 5 to 12, characterized in that the steps of the method are performed by a fuel heater control module of a flexible-fuel vehicle.

14. Fuel supply system (20) of an engine (26), characterized in that the fuel supply system comprises: a heated fuel injector (22) including a heater (80) and a body (78) that is heated by the heater; a fuel tank (24) that stores fuel; a fuel module (28) that supplies fuel from the fuel tank to the heated fuel injector; and a fuel heater control module (42) that controls the heater of the heated fuel injector; wherein the fuel heater control module detects a percentage of ethanol in the fuel used to operate the engine by the method as defined in claim 5.

15. Flexible fuel vehicle, characterized by the fact that Petition 870250101564, dated 06 / 11 / 2025, page 8 / 15 4 / 5 includes: an engine (26); a fuel supply system (20) that supplies fuel to the engine; the fuel supply system including a heated fuel injector (22) including a heater (80) that heats a body (78); and the fuel supply system additionally including a fuel heater control module (42) that controls the heated fuel injector heater; wherein the fuel heater control module detects a percentage of ethanol in the fuel used to operate the engine by the method as defined in claim 5.

16. Non-transient computer-readable medium, characterized in that it stores instructions that cause a controller to execute a method for detecting a percentage of ethanol in fuel used to operate an engine (26) of a flex-fuel vehicle, the method comprising the steps of: initiating a heating cycle in a heated fuel injector (22) of the engine (26), the heated fuel injector including a heater (80) that is operated during the heating cycle; monitoring the temperature of the heater of the heated fuel injector as a function of time; obtaining the temperature of the heater at a first time t1 at which a slope of the heater temperature as a function of time reaches a predetermined threshold value indicative of fuel boiling;Obtain the heater temperature at a subsequent time t2 where the heater temperature slope approaches a value of the slope prior to time t1 and which is greater than the predetermined threshold value indicative of fuel boiling; calculate a difference ΔT between the heater temperature at time t2 and the heater temperature at the first time t1; and determine the percentage of ethanol in the fuel as a function of the calculated temperature difference ΔT and the first time t1 where there was a change in slope.

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