Abstract:
A method is provided to indicate improper fuel filling in a vehicle. An indicator is actuated if a proportion of alcohol in the fuel is outside a range of expected proportions. In some examples, the range corresponds to a non-flex fuel vehicle recommended range, or to a normal range for a low alcohol-content fuel, which may be between 0 and 15 percent alcohol by volume. The indicator may include a diagnostic code or a dash light. Further, the indicator may be actuated in combination with a mitigating action, which may involve adjustment of a fuel injector pulse width or an ignition spark timing, as examples.

Description:
TECHNICAL FIELD 
   The present application relates to fault diagnosis and mitigation in motor vehicles, and more particularly to fueling error diagnosis and mitigation. 
   BACKGROUND 
   Motor-vehicle fuels of different compositions are sold alongside each other at filling stations. In particular, fuel mixtures comprising ethanol and gasoline are increasingly available, some of which may be used in conventional gasoline engines, while others may be used only in specially configured engines. E85, for instance, is a suitable fuel for so called flex-fuel vehicles: vehicles configured to run on widely varying fuel mixtures. Other mixtures, E10, for example, can be used in conventional gasoline engines so long as an appropriately homogenized mixture is provided. 
   However, some fuel distributors rely on splash blending during fuel transport to homogenize fuel mixtures. This method does not guarantee homogeneity and may result in a stratified mixture being supplied to the filling station. Thus, the mixture supplied to a customer&#39;s fuel tank may differ substantially from the expected composition. Moreover, stratification of a well-homogenized fuel mixture may occur on long standing in a vehicle&#39;s fuel tank as a result of repeated evaporation and condensation of fuel components. These factors may result in an inappropriately alcohol-rich fuel mixture being supplied to a gasoline engine not specially configured and/or controlled for alcohol-rich mixtures. 
   Further, vehicle fuel tank misfueling may be caused by simple, human error: a motorist or filling-station attendant may erroneously pump E85, for example, into a non-flex fuel vehicle. Results of misfueling may include degraded operation, e.g., stalling, difficulty starting, and rough idle. Further still, the misfueled motor vehicle may issue malfunction codes (MIL codes) that misdiagnose the problem. Misdiagnosis could trigger the servicing or replacement of non-defective, expensive parts, such as catalysts, fuel injectors, fuel pumps, exhaust gas oxygen sensors, or others. In addition, damage may occur to fuel-system or engine parts that are not resistant to high alcohol concentrations. 
   Finally, as alcohol-based fuels and alcohol-fueled vehicles become ever more common, the converse problem may arise: a vehicle designed to run on high-alcohol content fuel may be fueled erroneously with gasoline. 
   The inventors herein have recognized the above problems and have devised various solutions. For example, a method is provided to indicate improper fuel filling in a vehicle. In this method, an indicator is actuated if a proportion of alcohol in the fuel is outside a range of expected proportions. In some examples, the range corresponds to a non-flex fuel vehicle recommended range, or to an expected range for a low alcohol-content fuel, which may be between 0 and 15 percent alcohol by volume. The indicator may include a diagnostic code or a dash light. Further, the indicator may be actuated in combination with a mitigating action, which may involve adjustment of a fuel injector pulse width or an ignition spark timing, as examples. 
   It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows an example configuration of vehicle components in accordance with the present disclosure. 
       FIG. 2  illustrates, by way of a flow chart, an example algorithm for fueling error diagnosis and mitigation in accordance with the present disclosure. 
       FIG. 3  shows a schematic diagram of an owner&#39;s manual of a vehicle with an example fixed fueling indicator. 
       FIG. 4  shows a schematic diagram of a fuel door of a vehicle with an example fixed fueling indicator. 
   

   DETAILED DESCRIPTION 
     FIG. 1  shows an example configuration of vehicle components in accordance with the present disclosure.  FIG. 1  shows cylinder  102  with intake valve  104 , spark-ignition device  106 , fuel injector  108 , exhaust valve  110 , and crank-angle sensor  112 . Cylinder  102  may be one of several cylinders in an engine of a vehicle. In this example, at least some fuel enters cylinder  102  through fuel injector  108 . Air enters cylinder  102  through intake valve  104 . In some embodiments, fuel may enter the cylinder through the intake valve as well as the fuel injector. Thus, the configuration of components shown in  FIG. 1  is intended to enable direct injection and arbitrary combinations of direct and port injection. 
     FIG. 1  also shows air-fuel ratio sensor  114 , fuel tank  116 , refill sensor  118 , fuel composition sensor  120 , and controller  122 . Refill sensor  118  is a device installed in the vehicle and configured to generate an output signal that indicates when fuel has been added to a fuel tank of the vehicle. Fuel composition sensor  120  is a device installed in the fuel system of the vehicle and configured to generate an output signal that is a function of the alcohol content of the fuel, i.e., the proportion or relative amount of alcohol in the fuel. Note that the proportion of alcohol in a fuel may be expressed as a volume percent or as a weight percent, which are interconvertible if the composition or distribution of the alcohols in the fuel is known. Alcohols that may be included in motor-vehicle fuel blends include methanol, ethanol, isopropyl alcohol, and others. In this example, refill sensor  118  and fuel composition sensor  120  are enclosed within fuel tank  116 , but in other embodiments, they may be located elsewhere within the fuel system. In particular, fuel composition sensor  120  may be located within or in proximity to a conduit that conducts fuel from fuel tank  116  to a fuel pump of the vehicle. In this way, the fuel composition sensor may be configured to reflect specifically an alcohol content of the fuel entering the fuel pump (in the event that alcohol is distributed inhomogeneously within the fuel system). 
   Controller  122  is configured to accept input signals from crank-angle sensor  112 , air-fuel ratio sensor  114 , refill sensor  118 , and fuel composition sensor  120 . Controller  122  is further configured to provide control signals to spark-ignition device  106  and fuel injector  108 .  FIG. 1  also shows high-alcohol indicator  124  and low-alcohol indicator  126 , to which controller  122  is further configured to provide control signals. High-alcohol indicator  124  and low-alcohol indicator  126  are configured to receive control signals from controller  122  and to alert an operator of the vehicle when the alcohol content of the fuel is outside an expected range. In some embodiments, one or more of the indicators may be visual, e.g., an illuminated signal on a dashboard of the vehicle. In some embodiments, one or both of the indicators may be audible. In still other embodiments, one or both of the indicators may include setting a diagnostic code in an on-board diagnostic system of the vehicle. The code may indicate the manner of vehicle misfueling, e.g. alcohol content too high or too low, and may be readable by a universal diagnostic code reader of a kind known in the art. 
   Finally,  FIG. 1  shows fixed fueling indicator  128 , which indicates a range of expected proportions of alcohol in the vehicle fuel. In this example, fixed fueling indicator  128  is a label located on or close to fuel filling cap  130  that indicates the range implicitly in words. Other such examples might include “UNLEADED GASOLINE ONLY” or “GASOLINE/E10 ONLY,” to indicate that the expected range is 0 to 10 percent ethanol by volume. In still other examples, the range of expected proportions of alcohol may be stated more explicitly, “ALCOHOL 15% MAXIMUM,” for example. Any of these examples may be included as an indicator that the vehicle is a non-flex fuel vehicle. In other embodiments, fixed fueling indicator  128  may be separate from the vehicle but included as text in an owner&#39;s manual of the vehicle. The information conveyed by fixed fueling indicator  128  may in some embodiments be consistent with the language used to market the vehicle for sale. Thus, a vehicle comprising the components shown in  FIG. 1  and the fixed fueling indicator included therein may be marketed as a “gasoline-only” vehicle or a “non-flex fuel” vehicle. 
   It should be understood that  FIG. 1  is entirely schematic. The components included therein may comprise significant structure not shown in the figure. The structure that is shown may be rendered in a simplified form. For example, spark-ignition device  106  may comprise not only a spark plug, as the drawing suggests, but also a distributorless spark-ignition system that provides voltage to the spark plug. Likewise, controller  122  may comprise a plurality of interconnected electronic devices distributed throughout the vehicle. It should further be understood that  FIG. 1  is intended to be non-limiting. For instance, the vehicle engine may comprise additional cylinders with additional fuel injectors and additional sensors. Controller  122  may be configured to accept input signals from the additional sensors as well, and to provide control signals to the additional fuel injectors. 
     FIG. 2  illustrates, by way of a flow chart, an example algorithm by which controller  122  may execute fueling diagnosis and mitigation in accordance with the present disclosure. In describing the algorithm, continued numerical reference is made to the components of  FIG. 1 . At  202 , controller  122  determines if a refill of fuel tank  116  has occurred. In making this determination, controller  122  may rely on an input signal from refill sensor  118 . At  204 , controller  122  determines if a fuel composition sensor, e.g. fuel composition sensor  120 , is installed in the fuel system of the vehicle. If a fuel composition sensor is installed, then at  206 , controller  122  reads an output from the fuel composition sensor to determine the content of alcohol in the fuel. 
   If no fuel composition sensor is installed, then at  208 , controller  122  executes an alcohol-determining algorithm to determine the content of alcohol in the fuel. In one example, the alcohol-determining algorithm may include controller  122  metering an amount of fuel through fuel injector  108  and an amount of air through intake valve  104 , and receiving an input from air-fuel ratio sensor  114 . These steps may be performed iteratively, with one or more of the metered amounts adjusted at each iteration to maintain the air-fuel ratio sensor at stoichiometry. As is known in the art, the metered amounts may be used by controller  122  to calculate an oxygen content in the fuel, which may be used to estimate the alcohol content of fuel mixtures composed substantially of hydrocarbons and alcohol. 
   Whether determined by reading a sensor or by executing an alcohol-determining algorithm as described above, the alcohol content of the fuel is compared, at  210 , to threshold values A H  and A L , with A H &gt;A L . If the alcohol content of the fuel is between A H  and A L , it is indicated to be within the expected range for the vehicle. If the alcohol content of the fuel is above A H , then at  212 , controller  122  activates high-alcohol indicator  124 . If the alcohol content of the fuel is below A L , then at  214 , controller  122  activates low-alcohol indicator  126 . Note that the conditions A H =0, A L =0, A H =100% by volume, and A L =100% by volume are each allowed in some embodiments. 
   The example algorithm illustrated in  FIG. 2  further comprises adjusting one or more engine operating parameters with actuation of high-alcohol indicator  124  or low-alcohol indicator  126 . In this way, controller  122  may be configured to take mitigating action when a proportion of alcohol in the fuel system is unexpectedly high or low. At  216 , controller  122  adjusts a pulse width of a fuel-delivery pulse of fuel injector  108  based on the alcohol content of the fuel. The pulse width may be adjusted if the alcohol content of the fuel is above A H  and/or below A L . In some examples, controller  122  may be configured to increase the injector pulse width with increasing alcohol content of the fuel and to decrease the injector pulse width with decreasing alcohol content of the fuel. 
   At  218 , controller  122  adjusts a timing of spark-ignition device  106  based on the alcohol content of the fuel. The timing may be adjusted if the alcohol content of the fuel is above A H  and/or below A L . In some examples, controller  122  may be configured to advance the spark from spark-ignition device  106  with increasing alcohol content of the fuel and to retard the spark from spark-ignition device  106  with decreasing alcohol content of the fuel. 
   At  219 , controller  122  takes further mitigating action by adjusting other vehicle parameters based on the alcohol content of the fuel. The further mitigating action may be taken if the alcohol content of the fuel is above A H  and/or below A L . Examples of further mitigating action may include modifying how throttle position varies with torque request as a function of alcohol content, or changing a compression ratio of a turbocharger as a function of alcohol content. Such adjustments may be advantageous due to the lower power density of alcohol fuels relative to gasoline. 
   In this example, adjusting injector pulse width at  216 , adjusting spark timing at  218 , and adjusting other parameters at  219  are executed only when the alcohol content of the fuel is above A H  or below A L . In other embodiments, steps  216  to  219  may be executed as functions of the alcohol content of the fuel irrespective of whether said content is outside an expected range for the vehicle. 
   Continuing in  FIG. 2 , at  220 , controller  122  compares the alcohol content of the fuel to threshold values A HH  and A LL , with A HH ≧A H , A LL ≦A L , and A HH &gt;A LL . In one example, these values may bracket an alcohol-content interval outside of which the vehicle may not be able to operate acceptably. In other examples, they may bracket an interval outside of which serious damage to the vehicle may occur. If the alcohol content of the fuel is above A HH  or below A LL , then at  222 , controller  122  indicates to the operator of the vehicle that the alcohol content of the fuel is outside of a remediable operating range. In one example, the indication may include enhancing an output of high-alcohol indicator  124  or low-alcohol indicator  126 , such as by causing a panel lamp to blink, an audible indicator to sound more loudly, etc. 
   Finally, at  224 , controller  122  resets refill sensor  118  so that evaluation of the alcohol content in the fuel may be suspended until the next refill. Thus, in this example, the alcohol content of the fuel is evaluated, indicator status is updated, and mitigating actions are taken only once with each refill event. Other embodiments are contemplated, however, in which steps  204  through  222  are executed repeatedly throughout the fueling cycle. 
     FIGS. 3 and 4  are included to illustrate example dispositions of fixed fueling indicators in accordance with the present disclosure. Thus,  FIG. 3  shows a schematic diagram of owner&#39;s manual  300  of a vehicle with fixed fueling indicator  128  as text in the owner&#39;s manual.  FIG. 4  shows a schematic diagram of fuel door  400  of a vehicle with fixed fueling indicator  128  as a label juxtaposed to fuel filling cap  130 . 
   It should be understood that the systems and methods described herein are exemplary in nature, and that these specific embodiments or examples are not to be considered in a limiting sense, because numerous variations are contemplated. Accordingly, the present disclosure includes all novel and non-obvious combinations of the various systems and methods disclosed herein, as well as any and all equivalents thereof.