Ethanol detection with heated fuel injectors in flexible-fuel vehicles

Abstract

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

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Application No. 18 / 119,395, filed March 9, 2023, the disclosure of which is incorporated by reference in its entirety.

[0002] The present disclosure relates generally to the detection of ethanol in engine fuels, and more particularly to measuring the ethanol content in fuels with heated components in automotive engine fuel delivery systems. [Background technology]

[0003] A flexible-fuel vehicle (also known as a flex-fuel vehicle, dual-fuel vehicle, total flex, flexifuel, hyflex, or simply flex vehicle) is a vehicle equipped with an internal combustion engine capable of operating on both conventional motor fuel (e.g., unleaded gasoline) and alternative fuels, such as ethanol or methanol, stored in the same fuel tank. The most common type of flexible-fuel vehicle has an engine capable of running 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 containing up to 85% anhydrous ethanol by volume, and may actually contain between 51% and 85% anhydrous ethanol, depending on the region and seasonal temperature. Other common gasoline-ethanol blends include E10 (up to 10% absolute ethanol), E20 (up to 20% absolute ethanol), E25 (up to 25% absolute ethanol), E70 (up to 70% absolute ethanol), and E75 (up to 75% absolute ethanol). Pure ethanol (E100) contains no gasoline and is 100% hydrous ethanol, consisting of an average of 5.3% water by volume and the remainder ethanol. Due to its inherent water content, pure ethanol is sometimes referred to as E95.

[0004] The type / mix of fuel used in a flexible-fuel vehicle can be changed based on user preferences and the availability of various fuel blends described above. For example, after a user fills a flexible-fuel vehicle's fuel tank with gasoline, the user can then replace the tank with E85 fuel when the tank is empty and / or needs to be refilled. Thus, the user can freely switch between gasoline (which does not contain ethanol in its pure form, but gasoline currently sold at gas stations in the United States may contain up to 10% ethanol) and E85, which is more than half ethanol. As the example in Figure 1 shows, when refilling a fuel tank converted from a low-ethanol blend to a high-ethanol blend, it takes approximately 400 seconds with the engine idling for the old (original) fuel to be removed from the fuel lines of the vehicle's fuel delivery system and for the onboard control module to complete learning the ethanol content of the new fuel. Therefore, for some flexible-fuel vehicles, it is recommended that the vehicle be driven at least four miles (approximately 11 kilometers) after refueling to allow sufficient time for the vehicle's computer to learn the ethanol content in the fuel tank and make any necessary driving adjustments. If a flexible-fuel vehicle is not given enough time to learn the ethanol content when switching from gasoline to ethanol or ethanol blends, the user may experience engine ignition issues the next time the vehicle is cold-started after refueling. Therefore, this period following a refueling event, when a switch occurs between gasoline and ethanol / ethanol blends, is a vulnerable point in the vehicle's computer system's learning of the ethanol. In particular, in spark-ignition engines fueled by gasoline, ignition of the fuel / air mixture occurs readily except at very low temperatures (i.e., below -40°C) due to gasoline's relatively low flash point ("flash point" is defined herein as the lowest temperature at which a fuel can form an ignitable mixture in air).However, spark-ignition engines fueled by alcohol-based fuels, such as ethanol (E100) or ethanol-gasoline blends (e.g., E85), which have much higher flash points, may not ignite the fuel / air charge in cold weather conditions. For example, the flash point of ethanol is approximately 12.8°C. Therefore, starting an ethanol-fueled spark-ignition engine may be difficult or impossible under the cold ambient temperatures experienced seasonally in many parts of the world, a problem that may be exacerbated by the engine's computer not recognizing the change in fuel type.

[0005] Traditionally, the ethanol content in fuel stored in a vehicle's fuel tank is detected and measured using an ethanol sensor located in the fuel line or by an 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 fuel's electrical capacitance. However, given the significant delay time it takes for a vehicle to learn the ethanol content of a fuel using traditional methods (e.g., when the oxygen sensor measures the post-combustion mixture), and the potential undesirable effects this delay can have, an alternative method for determining the ethanol content of fuel used in flexible-fuel vehicles is needed. Summary of the Invention [Means for solving the problem]

[0006] A method for detecting the percentage of ethanol in a fuel used by an engine is provided. The method includes initiating a heating cycle in a component of a fuel supply system of the engine, the component including a heater. The method further includes monitoring the temperature of the heater as a function of time, the heater being activated during the heating cycle. The method further includes 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 indicative of boiling of the fuel. The method further includes obtaining the temperature of the heater at a subsequent time t2 at which the slope of the heater temperature approaches a slope value that is earlier than the first time t1 and is greater than the predetermined threshold indicative of boiling of the fuel. The method further includes calculating a temperature 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.

[0007] In certain embodiments, the heating cycle begins before the engine is ignited.

[0008] In certain embodiments, the heating cycle is initiated after a refueling event.

[0009] In a particular embodiment, the component is a heated fuel injector.

[0010] In certain embodiments, the heater heats the body of the heated fuel injector.

[0011] A method for detecting the percentage of ethanol in a fuel used to operate an engine of a flexible-fuel vehicle is also provided. The method includes initiating a heating cycle in a heated fuel injector of the engine, the heated fuel injector including a heater that is activated during the heating cycle. The method further includes monitoring the temperature of the heater of the heated fuel injector as a function of time. The method further includes obtaining the heater temperature at a first time t1 at which a slope of the heater temperature as a function of time reaches a predetermined threshold indicative of boiling of the fuel. The method further includes obtaining the heater temperature at a subsequent time t2 at which the slope of the heater temperature approaches a slope value that is greater than the predetermined threshold indicative of boiling of the fuel, the slope value being a value prior to the first time t1. The method further includes calculating a temperature 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 at which the change in slope occurs.

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

[0013] In certain embodiments, the heating cycle is initiated after adding fuel to the fuel tank of a flexible-fuel vehicle.

[0014] In certain embodiments, the heating cycle begins before the engine is ignited.

[0015] In certain embodiments, the duration of the heating cycle is between 5 and 10 seconds.

[0016] In certain embodiments, the percentage of ethanol is determined by the following formula (I): Percentage of ethanol in fuel (%)=C+αt1−β(ΔT).

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

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

[0019] In certain embodiments, the determined percentage of ethanol in the fuel has a margin of error of ±15%.

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

[0021] A fuel delivery system for an engine is also provided. The fuel delivery system includes a heated fuel injector including a heater and a body heated by the heater. The system further includes a fuel tank for storing fuel and a fuel module for delivering 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 the percentage of ethanol in the fuel used to operate the engine using the method described herein.

[0022] A flexible-fuel vehicle is also provided. The flexible-fuel vehicle includes an engine and a fuel delivery system that delivers fuel to the engine. The fuel delivery system has a heated fuel injector including a heater that heats a body of the fuel injector. The fuel delivery system further includes a fuel heater control module that controls the heater of the heated fuel injector. The fuel heater control module detects the percentage of ethanol in the fuel used to operate the engine using the method described herein.

[0023] A non-transitory computer readable medium storing a program that causes a controller to perform a method for detecting the percentage of ethanol in a fuel used to operate an engine of a flexible-fuel vehicle is also provided.

[0024] Various advantages and aspects of the present disclosure may be understood in light of the following detailed description considered in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 is a graph showing the percentage of ethanol in the fuel at the fuel injector as a function of time after refilling the fuel tank when the engine is idling. [Figure 2] FIG. 2 is a schematic diagram of the engine fuel supply system. [Figure 3] FIG. 3 is a perspective view of a heated fuel injector used in some embodiments of the present disclosure. [Figure 4] FIG. 4 is a cutaway view of a portion of the heated fuel injector of FIG. [Figure 5] FIG. 5 is a flow diagram of a method for detecting the percentage of ethanol in a fuel used by an engine according to some embodiments of the present disclosure. [Figure 6] FIG. 6 is a diagram showing heat transfer from the heater surface to the fuel as a function of superheat. [Figure 7] FIG. 7 is a graph showing heater temperature as a function of time for various ethanol fuel types. [Figure 8] FIG. 8 is a graph illustrating a heating cycle of a heated fuel injector according to some embodiments of the present disclosure. [Figure 9] FIG. 9 is a scatter plot of ΔT for various known fuel ethanol contents. [Figure 10] FIG. 10 is a fitted line plot showing the calculated percentage of ethanol in fuel for various known fuel ethanol contents. [Figure 11] FIG. 11 is a histogram of the calculated percentage of ethanol in fuel for various known fuel ethanol contents. DETAILED DESCRIPTION OF THE INVENTION

[0026] A method for detecting the percentage of ethanol in a fuel used by an engine, as well as a fuel delivery system and a flexible-fuel vehicle using the method to detect the ethanol content in the fuel, are provided. Referring to FIGS. 2-11 , in which like numerals indicate corresponding components throughout the figures, the method utilizes a heated component in the vehicle's fuel delivery system 20. As a non-limiting example, the heated component is illustrated and generally designated as a heated fuel injector 22. While the heated component is illustrated as a heated fuel injector, it should be understood that the present invention is not limited to application to heated fuel injectors and is applicable to other heated components, such as a heated fuel rail. The method utilizes the existing heated component in the fuel delivery system 20 and provides rapid and accurate detection of ethanol in a fuel used by a vehicle without the need to include any additional components solely for the purpose of implementing the method. In other words, the method utilizes only the existing components of the engine's fuel delivery system. The method can also be performed before the engine is started, when the engine is not running. In contrast, existing methods for detecting ethanol in fuel can only be performed while the engine is running.

[0027] Referring initially to FIG. 2 , the fuel delivery system 20 includes a fuel tank 24 that stores a quantity of fuel for combustion in an internal combustion engine 26 and conversion into power. The fuel can be of any type, such as unleaded gasoline, a gasoline-ethanol blend, or pure ethanol. A fuel module 28 includes a fuel pump 30 and provides a source of pressurized fuel that is pumped to the heated fuel injectors 22. The heated fuel injectors 22 may be positioned upstream of the engine cylinders 32 and may inject fuel into intake ports 34 of the vehicle's intake manifold 36, for example. An evaporative emissions canister 38 captures fuel vapors present in the fuel tank 24; during engine operation, these vapors are removed from the canister by opening a canister valve 40 and delivered to the intake manifold 36. A fuel heater control module (FHCM) 42, in conjunction with an engine control module (ECM) 44, controls the heating and operation of the heated fuel injectors 22. The fuel heater control module 42 and engine control module 44 are powered by a battery 46 and control the delivery of fuel to the engine 26 and associated combustion via 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. Combustion products, including carbon dioxide and water, are exhausted from the engine cylinders 32 and discharged through an exhaust system 64, which includes a front oxygen sensor 66 and a rear oxygen sensor 68, respectively.

[0028] 3 and 4 , the exemplary heated fuel injector 22 has four connector pins 70a, 70b, 70c, and 70d, a fuel inlet end 72, a fuel discharge end 74, and a shell 76 that covers a fuel injector body 78. Typically, the heated fuel injector 22 is mounted to the engine 26, with the fuel inlet end 72 connected to the fuel module 28 and the fuel discharge end 74 positioned so that fuel passing through the fuel injector body 78 is discharged by the heated fuel injector 22 and utilized by the engine to operate the engine. As a non-limiting example, the connector pins 70a and 70b may be connected to an actuation coil within the fuel injector body 78 of the heated fuel injector 22, which actuates a valve also within the fuel injector body 78 and typically located at the fuel discharge end 74. Continuing with this example, when a voltage is applied across connector pins 70a and 70b, the valve opens, allowing fuel to flow from fuel inlet end 72, through fuel injector body 78, and out fuel discharge end 74. When the voltage is removed, or actively forced to zero volts, the valve closes, stopping or blocking the flow of fuel. By controlling the voltage applied to connector pins 70a and 70b, heated fuel injector 22 can be operated to controllably discharge fuel.

[0029] FIG. 4 shows a cutaway view of the shell 76 with the fuel injector body 78 removed. A heater, such as a heater element 80 formed from an electrically conductive material, is positioned to heat fuel within the fuel injector body 78 so that the heated fuel can be discharged by the heated fuel injector 22. The heater element 80 has a heater resistance such that when current flows through the heater element 80, heat is generated, which increases the heater temperature, thereby heating the heater element 80 and increasing the temperature of the fuel within the body and at the injector valve at the injector tip. As an illustrative, non-limiting example, the heater element 80 has a nominal resistance of 0.3 ohms at 20° C. When the heated fuel injector 22 is assembled, the heater element 80 is suitably thermally coupled to the fuel injector body 78 so as to be effective for heating the fuel passing through the fuel injector body 78. The heater element 80 may be formed, for example, of a thick film resistive material applied to the outside of the fuel injector body 78 or applied to the inside of the shell 76. Alternatively, the heater element 80 may be formed of a metal foil or wire suitably positioned to heat the fuel injector body 78 and thereby heat the fuel passing through the heated fuel injector 22. Connection points 81 and 82 on the heater 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. Pat. Nos. 7,766,254 and 9,587,604, the entire contents of which are incorporated herein by reference.

[0030] The heated fuel injector 22 also includes an integrated temperature sensing element or the like configured to measure the temperature of the injector heater element 80. By way of non-limiting example, the integrated temperature sensing element may be a temperature-dependent electrical device such as a thermistor 84. The thermistor 84 generally exhibits a resistance value corresponding to the thermistor temperature of the thermistor 84. The thermistor 84 may be formed of a thick-film material applied using methods similar to those used to apply the thick-film material to form the heater element 80. The thermistor 84 may also be a separate electrical component, such as a positive temperature coefficient (PTC) device or a negative temperature coefficient (NTC) device, attached using soldering or a similar method. The location of the thermistor 84 shown in FIG. 4 is one example of a suitable location and is not intended to be limiting. For example, if formed of a thick-film material, the thermistor 84 may cover the heater element 80, be separated from the heater element 80 by a layer of electrically insulating material, and be sized to sense temperature over a wide range of the heater element 80. By way of example, one such integrated temperature sensing element is shown in U.S. Patent Application Publication No. 2011 / 0276252, the entire contents of which are incorporated herein by reference. In other embodiments, the integrated temperature sensing element may be the injector heater element 80 itself.

[0031] The fuel heater control module 42 and the engine control module 44, individually or in cooperation, comprise a controller. Accordingly, as will be apparent to those skilled in the art, the controller may include a microprocessor or other control circuitry, such as an application-specific integrated circuit. The controller may also include memory, including random access memory (RAM) and non-volatile memory, such as electrically erasable programmable read-only memory (EEPROM), masked read-only memory (ROM), or flash memory, for storing one or more software routines, thresholds, and acquired data. The one or more software routines, including methods for detecting ethanol content in fuel, may be executed by the microprocessor to control engine components, including the heated fuel injector 22. The controller may also include analog-to-digital (A / D) and digital-to-analog (D / A) conversion circuitry, enabling the controller to establish electrical communication with devices external to the controller, such as the sensors described above. The controller may also include power supply circuitry.

[0032] 5 illustrates one non-limiting example of a method 100 for detecting the ethanol content of a fuel used in a flexible fuel injected internal combustion engine. The method 100 utilizes a heated fuel injector 22 including a heater element 80 configured to heat fuel in the heated fuel injector 22 and a temperature sensing element 84 capable of indicating the heater temperature. The heated fuel injector 22 is controlled by a controller configured to perform the steps of the method 100.

[0033] At step 102, a heating cycle is initiated in the heated fuel injector 22. The heating cycle involves activating the heater element 80 by supplying current to the heater element 80, which causes the heater element 80 to generate heat, generally increasing its temperature. The warming of the heater element 80 heats the fuel injector body 78 of the heated fuel injector 22, which in turn increases the temperature of the fuel within the injector body 78 adjacent the tip 86. The heating cycle may be initiated at any time, but preferably is initiated after a refueling event in which the controller detects that fuel has been added to the fuel tank 24, such as via a fuel level sensor 31 in the fuel module 28 within the fuel tank. Alternatively, or additionally, the heating cycle may be initiated prior to ignition of the engine 26, such as immediately prior to engine start, triggered by, for example, the opening of the driver's door, so that the ethanol content of the fuel can be measured prior to ignition and the controller can appropriately adjust engine operating parameters based on the determined ethanol content without a start-up delay for the driver / operator. As used herein, engine start-up refers to the time from an initial injection or priming injection event until the engine speed reaches a predetermined engine speed threshold, typically between 600 and 1000 revolutions per minute (RPM). Additionally, a heating cycle may also be initiated at any time during engine operation to periodically measure the ethanol content of the fuel. The duration of the heating cycle itself is long enough to raise the temperature of the heater element 80 above the boiling point of at least one component of the fuel, e.g., the boiling point of ethanol, which is 79°C, and to initiate vaporization of the fuel. 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, between 3 and 7 seconds, or between 5 and 7 seconds.

[0034] In step 104, the temperature of the heater element 80 of the heated fuel injector 22 is monitored as a function of time, such as the elapsed time of the heating cycle. The temperature of the heater element 80 may be obtained from the temperature sensing element 84 and temporarily recorded in the controller's memory as a function of the time of the heating cycle. The temperature of the heater element 80 continues 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, different fuel compositions cannot be easily distinguished during the initial heating phase before boiling. However, the heats of vaporization and boiling points are significantly different, which are useful for distinguishing between various fuel compositions. Pure ethanol boils at 79°C and exhibits a temperature plateau during vaporization because the thermal energy during boiling is dissipated in vaporization instead of further heating the liquid. In contrast, many components of gasoline boil between 25°C and 175°C. They do not exhibit the expected vaporization plateau, but rather multiple smaller plateaus that give the appearance of a continuum across the temperature range of interest. However, fuels containing significant amounts of ethanol begin to exhibit behavior characteristic of pure ethanol, with the pure behavior becoming increasingly more dominant as the ethanol content increases.

[0035] [Table 1]

[0036] The temperature of the heater element 80 is responsive to heat transfer factors, such as the formation and persistence of fuel bubbles on the heater surface, factors that do not affect the bulk fuel temperature. heater -T fuel ) shows the different stages of heater transfer.

[0037] Bulk fuel experiences a temperature increase based on its specific heat capacity until the phase transition to vapor begins. Because vaporization is an endothermic reaction, the temperature of the fuel does not increase further until the fuel is completely vaporized. Therefore, bulk fuel experiences a temperature increase followed by a temperature plateau, after which the temperature increase resumes. The monitored heater temperature behavior generally follows this pattern. Figure 7 shows the temperature profile versus ethanol content for E20, E60, and E100 fuels. E100 is a hydrous ethanol, while E20 and E60 are ethanol and gasoline mixtures (containing 20% ​​and 60% ethanol by volume, respectively). The behavior of E20 and E60 is intermediate between pure gasoline and pure ethanol depending on the ethanol content. Gasoline is already a mixture of components with different boiling points. Therefore, the higher the gasoline content and the lower the ethanol content in the fuel, the more diffuse the "vaporization plateau."

[0038] In step 106, the controller obtains, from the monitored heater element temperatures, a measured heater temperature at a first time t1 at which the slope of the heater temperature as a function of time reaches a predetermined threshold (i.e., the "vaporization plateau") indicative of boiling of the fuel. It will be appreciated that the slope of the temperature versus time characteristic may also be referred to as the time rate of change of temperature or the derivative of temperature with respect to time. Furthermore, the change in the slope of the heater temperature as a function of time may alternatively be referred to as the time rate of change of the temperature slope or the derivative of the temperature slope with respect to time. As noted above, the heater temperature rises to the point where boiling first occurs, and at that point (first time t1), the slope of the temperature versus time characteristic decreases significantly, possibly abruptly, depending on the ethanol content of the fuel. Depending on the ethanol content, the slope may exhibit an inflection at the first time t1, changing from positive to negative; a lower ethanol content (i.e., closer to pure gasoline) results in a steeper decrease in slope, with the rate of change of slope exhibiting a steeper negative decrease. In either case, at the onset of boiling, the slope will be less than zero, or will be zero, or will decrease to a value approaching zero, so that the slope is below a predetermined threshold near zero, and the rate of change of the slope is negative, i.e., the slope is decreasing with time. Thus, in step 106, the slope of the temperature versus time characteristic is compared to a predetermined threshold indicative of fuel boiling, which may be a slightly positive slope near zero, a zero-value slope, or a slope less than zero.

[0039] At the onset of boiling, latent heat energy is absorbed to allow the fuel to change from a liquid phase to a vapor phase. Thereafter, while this phase change is occurring, the fuel temperature remains essentially constant, at the boiling point of the vaporized fuel. In step 108, the controller obtains a measured heater temperature at a subsequent time t2 from the monitored heater element temperature. Time t2 refers to the point at or after t2 when the heater temperature slope approaches the value of the slope prior to the change in slope at the first time t1. Approaching the heater temperature slope prior to the change in slope at the first time t1 means that the slope has changed from zero or near zero to a positive value close to the slope at the previous time and greater than a predetermined threshold, or the rate of change of the slope indicates a positive increase. The point at time t2 corresponds to the point at which all the fuel has vaporized (stabilized film boiling) and the temperature rise resumes, as shown in FIG. 6 . 8, an example of a heater element curve of temperature versus time is shown, with the elapsed time until the temperature change (slope "break" reference time t1) indicated as duration A, the temperature at time t1 indicated as point B, the temperature at a subsequent time t2 indicated as point D, and the elapsed time from the onset of vaporization to vaporization stabilization (the time from point B to point D) indicated as duration C. It should be understood that the first time t1 is measured from the time an increase in the temperature of the heating element is observed after the start of the heating cycle to point B, where the slope of the heating element temperature suddenly changes. In other words, the temperature of the heating element may not begin to increase until slightly after time zero, which is the start of the heating cycle (e.g., a value greater than zero seconds and less than one second), and time t1 is the difference between the time the temperature at point B is obtained and the time the temperature of the heating element begins to increase (which may be zero seconds or slightly greater than zero seconds). In other words, the first time t1 is duration A, which is the time elapsed from the start of the temperature increase to the "change" in temperature at point B.

[0040] In step 110, a temperature difference (ΔT) between the heater temperature obtained at time t2 and the heater temperature obtained at a first time t1 is calculated. As shown in FIG. 9, there is a clear relationship between the ethanol content (vol %) of the fuel and the temperature difference ΔT. Next, 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 t1 at which a change in the heater temperature slope occurred. Specifically, the following equation (I) is used: Percentage of ethanol in fuel (%) = C + αt1 - β(ΔT) The ethanol percentage is determined by Here, the constant C and coefficients α and β are obtained by linear regression of experimental data points obtained from various known ethanol contents, such as E100, E60, and E20. A fitted line plot of these data points, including confidence intervals and population interval boundaries, is shown in Figure 10. A histogram of the same data and calculated ethanol percentages is shown in Figure 11. As can be seen, the ethanol percentage determined by this method can be determined with high confidence, within ±15 percentage points, of the actual ethanol volume percent concentration of the fuel. For example, if the fuel is E60 (actual ethanol content 60% by volume), the determined ethanol content will range from approximately 45% to 75% at most. However, the ethanol content determined by this method may fall within a narrower range. These results are within the same confidence interval as other ethanol learning methods, such as methods based on data obtained from oxygen sensors. In a specific embodiment, the constant C is 49.95, the coefficient α is 5.22, and the coefficient β is 2.8319. However, the values ​​of the formula (C, α, β) may be adjusted based on empirical linear regression using additional and / or alternative experimental data points obtained from known fuel ethanol concentrations. In some embodiments, the values ​​may be within ±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.

[0041] It is understood that the scope of the appended claims is not limited to the explicit and specific compounds, compositions, or methods described in the detailed description, which may vary among specific embodiments falling within the scope of the appended claims. With respect to any Markush group relied upon herein to describe particular features or aspects of various embodiments, different, unique, and / or unexpected results may be obtained from each member of the respective Markush group, independently of all other Markush members. Each member of a Markush group may be relied upon individually and / or in combination to provide sufficient support for specific embodiments within the scope of the appended claims.

[0042] Furthermore, all ranges and subranges relied upon to describe various embodiments of the invention are understood to be individually and collectively within the scope of the appended claims and to describe and contemplate all ranges, including integer and / or fractional values ​​therein, even if such values ​​are not explicitly recited. Those skilled in the art will readily recognize that the recited ranges and subranges are sufficient to describe and enable various embodiments of the invention, and that these ranges and subranges may be further subdivided into related halves, thirds, quarters, fifths, etc. As an example, a range of "0.1 to 0.9" may be further subdivided into a lower third, i.e., 0.1 to 0.3, a middle third, i.e., 0.4 to 0.6, and an upper third, i.e., 0.7 to 0.9, which are individually and collectively within the scope of the appended claims and may be relied upon individually and / or collectively to fully support particular embodiments within the scope of the appended claims. Furthermore, when terms such as "at least," "greater than," "less than," "less than or equal to," and the like are used to define or modify a range, it is to be understood that such terms include subranges and / or upper or lower limits. As another example, the range "at least 10" inherently includes subranges from at least 10 to 35, from at least 10 to 25, from 25 to 35, etc., each of which may be relied upon individually and / or collectively to provide sufficient support for particular embodiments within the appended claims. Finally, individual numerical values ​​within the disclosed ranges may be relied upon in particular embodiments within the appended claims to provide sufficient support for those particular embodiments. For example, the range "1 to 9" includes various individual integers, such as 3, as well as individual numerical values ​​(or fractions) containing a decimal point, such as 4.1, which may be relied upon in particular embodiments within the appended claims to provide sufficient support for those particular embodiments.

[0043] The above description relates to current embodiments of the invention. Various changes and modifications may be made without departing from the spirit and broad aspects of the invention, as defined in the appended claims, which are to be construed in accordance with patent law principles, including the doctrine of equivalents. This disclosure is presented for illustrative purposes and should not be construed as an exhaustive description of all embodiments of the invention, nor should the claims be limited to the specific elements shown or described in connection with these embodiments. For example, but not limited to, any individual element of the described invention may be replaced by an alternative element providing substantially similar functionality, or an alternative element that provides sufficient operation. This includes, for example, currently known alternatives, such as those that may currently be known to those of ordinary skill in the art, and alternatives that may be developed in the future, such as those that may recognize as alternatives at the time of development. Furthermore, the disclosed embodiments include multiple features that are described together and that may, in combination, provide a series of advantages. The invention is not limited to embodiments including all of these features or providing all of the described advantages, except to the extent expressly defined in the issued claims. Reference to a claim element in the singular, for example, using the articles "a," "an," "the," or "said," should not be construed as limiting the element to the singular.

Claims

1. 1. A method for detecting the percentage of ethanol in a fuel used in an engine (26), comprising: The method comprises: initiating a heating cycle within a component (22) of a fuel delivery system (20) of the engine (26), the component including a heater (80); monitoring the temperature of the heater as a function of time, the heater being activated during the heating cycle; a first time t at which the slope of the heater temperature as a function of time reaches a predetermined threshold indicative of fuel boiling; １ acquiring a temperature of the heater; The temperature gradient of the heater is １ At a subsequent time t, the slope approaches a slope value that is greater than the predetermined threshold value, which is indicative of fuel boiling. ２ acquiring a temperature of the heater; The subsequent time t ２ the temperature of the heater at the first time t １ calculating a temperature difference ΔT between the temperature of the heater at The calculated temperature difference ΔT and the first time t １ and determining the percentage of ethanol in the fuel as a function of

2. 10. The method of claim 1, wherein the heating cycle is initiated i) before ignition of the engine, ii) after a refueling event, or iii) at i) and ii).

3. The method of claim 1 or 2, wherein the component is a heated fuel injector.

4. The method of claim 3 , wherein the heater heats a body of the heated fuel injector.

5. 1. A method for detecting the percentage of ethanol in a fuel used to operate an engine (26) of a flexible-fuel vehicle, comprising: 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) that is activated during the heating cycle; monitoring the temperature of the heater of the heated fuel injector as a function of time; a first time t at which the slope of the heater temperature as a function of time reaches a predetermined threshold indicative of fuel boiling; １ acquiring a temperature of the heater; The temperature gradient of the heater is １ At a subsequent time t, the slope approaches a slope value that is greater than the predetermined threshold value, which is indicative of fuel boiling. ２ acquiring a temperature of the heater; The subsequent time t ２ the temperature of the heater at the first time t １ calculating a temperature difference ΔT between the temperature of the heater at The first time t at which the calculated temperature difference ΔT and the slope change １ and determining the percentage of ethanol in the fuel as a function of

6. The method of claim 5 , wherein the heating cycle comprises heating the body of the heated fuel injector for a period of time.

7. 7. The method of claim 5 or 6, wherein the heating cycle is initiated i) after adding fuel to the fuel tank of the flexible-fuel vehicle, ii) before ignition of the engine, or iii) at both i) and ii).

8. 8. The method according to any one of claims 5 to 7, wherein the duration of the heating cycle is between 5 and 10 seconds.

9. The proportion of ethanol is determined by the following formula (1): Percentage of ethanol in fuel (%) = C + αt １ The method according to any one of claims 5 to 8, wherein the temperature is determined by -β(ΔT).

10. 10. The method of claim 9, wherein C is 49.95±2.50, α is 5.22±0.26, and β is 2.8319±0.1416.

11. 10. The method of claim 9, wherein the values ​​in equation (1) are determined based on empirical linear regression using experimental data points obtained from known fuel ethanol concentrations.

12. 12. The method of any one of claims 5 to 11, wherein the determined percentage of ethanol in the fuel has an error range of ±15%.

13. The method of any one of claims 5 to 12, wherein the steps of the method are performed by a fuel heater control module of the flexible-fuel vehicle.

14. A fuel supply system (20) for an engine (26), comprising: The fuel supply system includes: a heated fuel injector (22) including a heater (80) and a body (78) heated by the heater; a fuel tank (24) for storing fuel; a fuel module (28) that supplies fuel from the fuel tank to the heated fuel injector; a fuel heater control module (42) for controlling the heater of the heated fuel injector; 6. A fuel delivery system, wherein the fuel heater control module detects the percentage of ethanol in the fuel used to operate the engine according to the method of claim 5.

15. 1. A flexible-fuel vehicle, comprising: an engine (26); a fuel supply system (20) for supplying fuel to the engine; The fuel supply system includes a heated fuel injector (22) including a heater (80) that heats a body (78); The fuel supply system further includes a fuel heater control module (42) that controls the heater of the heated fuel injector; 6. A flexible-fuel vehicle, wherein the fuel heater control module detects the percentage of ethanol in the fuel used to operate the engine according to the method of claim 5.

16. 1. A non-transitory computer-readable medium storing a program that causes a controller to execute a method for detecting a percentage of ethanol in a fuel used to operate an engine (26) of a flexible-fuel vehicle, the method comprising: The method comprises the following steps: initiating a heating cycle in a heated fuel injector (22) of the engine (26), the heated fuel injector including a heater (80) that is activated during the heating cycle; monitoring the temperature of the heater of the heated fuel injector as a function of time; a first time t at which the slope of the heater temperature as a function of time reaches a predetermined threshold indicative of fuel boiling; １ acquiring a temperature of the heater; The temperature gradient of the heater is １ At a subsequent time t, the slope approaches a slope value that is greater than a predetermined threshold value that indicates fuel boiling. ２ acquiring a temperature of the heater; The subsequent time t ２ the temperature of the heater at the first time t １ calculating a temperature difference ΔT between the temperature of the heater at The first time t at which the calculated temperature difference ΔT and the slope change １ and determining the percentage of ethanol in the fuel as a function of

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