Abstract:
An automotive vehicle includes an engine, a plurality of electrical load subsystems, and at least one controller. During an auto start of the engine, the at least one controller detects a starter disengage condition. In response to detecting the starter disengage condition, the at least one controller periodically determines a value of an operating parameter associated with the vehicle, causes a first subset of the electrical load subsystems to be enabled when the value of the operating parameter falls with a first predefined range of values, and causes a second subset of the electrical load subsystems to be enabled when the value of the operating parameter falls within a second predefined range of values.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure relates to algorithms and systems implementing the same for enabling or “turning on” electrical subsystems during an engine auto start. 
       BACKGROUND 
       [0002]    A micro-hybrid vehicle may automatically stop its internal combustion engine for a period of time during intervals of a drive cycle when vehicle speed approaches or is equal to zero. These engine auto stops may improve fuel economy by reducing engine idle time (and thus fuel consumption) for the drive cycle. 
       SUMMARY 
       [0003]    A method for controlling a plurality of vehicle electrical load subsystems may include, during an auto start of an engine, enabling a first subset of the subsystems when a value of a vehicle operating parameter falls with a first predefined range of values, and enabling a second subset of the subsystems when the value of the parameter falls within a second predefined range of values. 
         [0004]    An automotive vehicle may include an engine, a plurality of electrical load subsystems, and at least one controller configured to cause, during an auto start of the engine, the subsystems to be sequentially enabled according to a priority associated with each of the subsystems and a value of at least one operating parameter associated with the vehicle. 
         [0005]    An automotive vehicle may include an engine, a plurality of electrical load subsystems, and at least one controller. The at least one controller may be configured to detect, during an auto start of the engine, a starter disengage condition, and in response to detecting the starter disengage condition, periodically determine a value of an operating parameter associated with the vehicle, cause a first subset of the electrical load subsystems to be enabled when the value of the operating parameter falls with a first predefined range of values, and cause a second subset of the electrical load subsystems to be enabled when the value of the operating parameter falls within a second predefined range of values. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a block diagram of a micro-hybrid vehicle. 
           [0007]      FIG. 2  is a plot of engine status versus time before, during and after an engine stop/start event. 
           [0008]      FIG. 3  is a flow chart of an algorithm for determining when to enable electrical loads during an engine auto start. 
       
    
    
     DETAILED DESCRIPTION 
       [0009]    As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. 
         [0010]    Referring to  FIG. 1 , a micro hybrid vehicle  10  may include an engine  12 , an alternator or integrated starter generator  14 , a battery  16  (e.g., a 12 V battery), electrical load subsystems  18  (e.g., electric power steering assist system, electric park brake system, HVAC blower system, heated windshield system, etc.) in communication with/under the control of one or more controllers  20  (as indicated by dashed line). The engine  12  is mechanically connected with the alternator or integrated starter generator  14  (as indicated by heavy line) such that the engine  12  may drive the alternator or integrated starter generator  14  to generate electric current. The alternator or integrated starter generator  14  and battery  16  are electrically connected with each other and the electrical load subsystems  18  (as indicated by thin line). Hence, the alternator or integrated starter generator  14  may charge the battery  16 ; the electrical load subsystems  18  may consume electric current provided by the alternator or integrated starter generator  14  and/or battery  16 . 
         [0011]    The controllers  20  may initiate an auto stop or auto start of the engine  12 . As the vehicle  10  comes to a stop, for example, the controllers  20  may issue a command to begin the process to stop the engine  12 , thus preventing the alternator or integrated starter generator  14  from providing electric current to the electrical load subsystems  18 . The battery  16  may provide electric current to the electrical load subsystems  18  while the engine  12  is stopped. As a brake pedal (not shown) is disengaged (and/or an accelerator pedal (not shown) is engaged) after an engine auto stop, the controllers  20  may issue a command to begin the process to start the engine  12 , thus enabling the alternator or integrated starter generator  14  to provide electric current to the electrical load subsystems  18 . 
         [0012]    Referring to  FIG. 2 , an engine auto stop event may include several stages. “Auto-stop begin” marks the beginning of the engine auto stop event. “Preparing for engine auto-stop” is the time period during which vehicle systems as well as the engine are prepared for the impending engine stop. If an auto stop inhibit condition is detected during this stage, the preparation for the impending engine stop is discontinued and the vehicle systems and engine are returned to their normal operating modes. “Fuel shutoff” marks the point at which fuel flow to the engine is stopped. “Engine stopping” is the time period during which the engine speed reduces to 0. “Below fuel restart” marks the point after which if a restart is requested during the “engine stopping” stage, the starter may need to be engaged to crank the engine. If a restart is requested before “below fuel restart” and during the “engine stopping” stage, the engine may be restarted by turning the flow of fuel back on. “Engine speed=0” marks the point at which the engine speed is near or equal to 0. 
         [0013]    “Engine auto-stopped” is the time period during which the engine is off. “Starter engage” marks the point at which the starter starts to crank the engine in an effort to start the engine in response to detecting an engine auto start condition. “Starter cranking engine” is the time period during which the engine is unable to crank under its own power. “Starter disengage” marks the point at which the engine is able to crank under its own power. “Engine speed increasing” is the time period during which the speed of the engine increases to its running speed (a speed at or above target idle speed). “Auto-start end” marks the point at which the speed of the engine achieves its running speed. 
         [0014]    Certain of the electrical load subsystems  18  may have their functionality restricted or be “turned off” during the “engine auto-stopped” stage. As an example, an electric power steering assist system may be disabled as such assist may be unnecessary while the vehicle  10  is stopped. An electric park brake system may be disabled for similar reasons. As another example, an HVAC blower system and/or heated windshield system may be disabled to reduce the amount of electric current required during an auto stop of the engine  12 . Other scenarios are also possible. 
         [0015]    Electrical load subsystems that have their functionality restricted or disabled during the “engine auto-stopped” stage may have their functionality restored or “turned on” during the “engine speed increasing” stage for at least two reasons: movement of the vehicle  10  may be imminent so electrical load subsystems such as the electric power steering assist system and electric park brake system may be needed; the alternator or integrated starter generator  14  is able to supply at least some electric current during this stage so there may no longer be a need to limit the amount of electric current demanded as before. Restoring functionality or “turning on” restricted or disabled loads at the same time while the speed of the engine  12  is increasing, however, may cause large drops in system voltage: the alternator or integrated starter generator  14  may not be able to handle sudden increases in electric current demand before being fully operational. Hence, strategies and systems implementing the same are described for preventing restricted or disabled loads from being restored or “turned on” at the same time while engine speed increases following an auto start. 
         [0016]    The electrical load subsystems  18  may be classified or categorized, in certain examples, according to priority. That is, certain of the electrical load subsystems  18  may be more necessary than others. For example, an electric power steering assist system may be more important to a driver as compared with a heated windshield system. The electric park brake system may be more important to a driver compared with an HVAC blower system, etc. Hence, the aforementioned loads may be classified into four categories (or any number of desired categories): category 1—electric power steering assist system; category 2—electric park brake system; category 3—HVAC blower system; and, category 4—heated windshield system. As described in more detail below, restricted or disabled loads may be restored or “turned on” sequentially according to their categorization. Any suitable ranking system for any number of electrical load subsystems, however, may be used. As an example, electrical loads may be ranked according to the amount of current they require. Loads requiring relatively less current may be ranked higher than loads requiring relatively more current, etc. Additionally, certain loads that are designed such that they cannot be controlled electronically may also be considered when determining the ranking or prioritization. 
         [0017]    In certain examples, a particular category of the electrical load subsystems  18  may be restored or “turned on” if the speed of the engine  12  falls within a particular range. Continuing with the example above, four speed ranges may be defined: range 1-W to X (RPM); range 2-X to Y (RPM), range 3-Y to Z (RPM); and, range 4-Z to a speed greater than target idle speed (RPM), where W&lt;X&lt;Y&lt;target idle speed, and where Y&lt;Z. W, X, Y and Z may be determined via testing, simulation, etc. such that, for example, system performance is balanced with customer expectations. The controllers  20  may monitor the speed of the engine  12  and restore or “turn on” category 1 subsystems when the engine speed falls within range 1. The controllers  20  may restore or “turn on” category 2 subsystems when the engine speed falls within range 2, etc. Alternatively, the controllers  20  may broadcast the speed range of the engine  12 . The electrical load subsystems  18  may monitor such information broadcast by the controllers  20  and enable themselves when appropriate in response. 
         [0018]    Engine speed is used in the above example because it is assumed that the output of the alternator or integrated starter generator  14  is a function of engine speed (as the engine  12  mechanically drives the alternator or integrated starter generator  14 ). Hence, the greater the engine speed, the greater the capability of the alternator or integrated starter generator to generate output. In other examples, output (voltage, current, etc.) of the alternator or integrated starter generator  14  may be monitored and used to determine when to restore or “turn on” certain electrical loads. The greater the output, the greater the number of electrical loads that may be enabled. Other parameters may also be used. A particular category of electrical load subsystems may be restored or “turned on” if a certain amount of time has passed since “starter disengage.” Category 1 subsystems may be restored or “turned on” immediately following “starter disengage.” Category 2 subsystems may be restored or “turned on” if at least Q seconds have passed since “starter disengage,” etc. Combinations of parameters may also be used. As an example, alternator or integrated starter generator output and time may be used such that a particular category of electrical load subsystems is not enabled until there is sufficient output and at least a certain amount of time has passed since “starter disengage.” Other scenarios are also contemplated. 
         [0019]    Vehicle passengers may attempt to enable certain of the electrical load subsystems  18  during a stop/start event. For example, a driver may attempt to “turn on” a radio subsystem or a climate subsystem while the engine  12  is auto stopped. Depending on when such attempts are made, they may conflict with the strategies described herein for sequentially enabling the various electrical loads. That is, a driver may happen to try to “turn on” a climate subsystem immediately after “starter disengage.” If, however, the climate subsystem is not categorized to be enabled immediately after “starter disengage,” the driver&#39;s request may not be honored until the category that the climate subsystem falls within is cleared to be enabled. Assuming in this example, that the climate system is not scheduled to be enabled until the alternator or integrated starter generator output achieves some predetermined threshold, the driver&#39;s request may not be honored until the alternator or integrated starter generator output achieves the predetermined threshold. 
         [0020]    Referring to  FIG. 3 , it is determined whether the starter has disengaged from cranking the engine at operation  22 . For example, the controllers  20  may monitor a controller area network for information (e.g., a status flag, etc.) indicating that the “starter disengage” stage has ended. If no, the algorithm returns to operation  22 . If yes, value(s) of the parameter(s) used to determine whether to enable the electrical load subsystems are determined at operation  24 . The controllers  20 , for example, may read information regarding engine speed, system current, and/or time passed since the end of “starter disengage,” etc. At operation  26 , electrical load subsystems are restored or “turned on” based on the priority of the particular electrical load subsystem under consideration and the values determined at operation  24 . For example, the controllers  20  may read information about alternator or integrated starter generator output, categorize the information, and broadcast a category associated with the information. If the output is between α and β (V), then the controllers  20  may broadcast a category 1 indicator. The electrical load subsystems  18  may monitor communication lines with the controllers  20  and operate to enable themselves if they are classified as a category 1 subsystem. If the output is between β and γ (V), then the controllers  20  may broadcast a category 2 indicator, and so forth. Alternatively, the controllers  20  may be arranged so as to control the enabling of the electrical load subsystems  18 . The controllers  20 , in these circumstances, need not broadcast category information. Rather, the controllers  20  may read information about output, categorize the information, and enable the electrical load subsystems  18  directly based on the categorization and the priority associated with the electrical load subsystems  18 . Other scenarios are also contemplated. At operation  28 , it is determined whether all of the electrical load subsystems are enabled. The controllers  20 , for example, may request status information from each of the electrical load subsystems  18 . The controllers  20  may alternatively detect status of each of the electrical load subsystems  18 . If no, the algorithm returns to operation  24 . If yes, the algorithm ends. 
         [0021]    The algorithms disclosed herein may be deliverable to/implemented by a processing device, such as the controllers  20 , which may include any existing electronic control unit or dedicated electronic control unit, in many forms including, but not limited to, information permanently stored on non-writable storage media such as ROM devices and information alterably stored on writeable storage media such as floppy disks, magnetic tapes, CDs, RAM devices, and other magnetic and optical media. The algorithms may also be implemented in a software executable object. Alternatively, the algorithms may be embodied in whole or in part using suitable hardware components, such as Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), state machines, or other hardware components or devices, or a combination of hardware, software and firmware components. 
         [0022]    While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.