Abstract:
A control system for an internal combustion engine is provided. The control system includes an engine movement module that selects from N engine rotation modes based on camshaft movement and crankshaft movement, where N is an integer greater than two, and where at least one of the N rotation modes is an assisted spinning mode. A diagnostic module enables one or more engine diagnostic modes based on the selected engine rotation mode.

Description:
FIELD 
     The present invention relates to systems and methods for detecting engine movement of an internal combustion engine. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     An internal combustion engine includes an intake camshaft that controls the flow of air entering the engine. The air is combined with fuel and combusted within a cylinder. The combustion drives a piston which, in turn, drives a crankshaft to produce drive torque. Exhaust gas from the combustion exits the engine by control of an exhaust camshaft. 
     One or more sensors detect rotation of the camshafts and/or the crankshaft. Sensor signals indicate whether the engine is rotating and thus, operational. Diagnostics are performed to confirm operation of the sensors and the engine. In some cases, the diagnostics do not run when the engine is starting to rotate, which may prevent the engine from starting. In other cases, the diagnostics set faults when the engine stops rotating. This may result in improper detection of faults, which may impact drivability. 
     SUMMARY 
     Accordingly, a control system for an internal combustion engine is provided. The control system includes an engine movement module that selects from N engine rotation modes based on camshaft movement and crankshaft movement, where N is an integer greater than two, and where at least one of the N rotation modes is an assisted spinning mode. A diagnostic module enables one or more engine diagnostic modes based on the selected engine rotation mode. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is a functional block diagram of a vehicle including an engine movement detection system according to various aspects of the present disclosure. 
         FIG. 2  is a dataflow diagram illustrating an engine movement detection system according to various aspects of the present disclosure. 
         FIG. 3  is a state transition diagram illustrating an engine movement detection model according to various aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. As used herein, the term module refers to an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. 
     Referring now to  FIG. 1 , an exemplary vehicle  10  includes an engine  12  that drives a transmission  14 . The transmission  14  can be either an automatic or a manual transmission that is driven by the engine  12  through a corresponding torque converter or clutch  16 . The engine  12  includes N cylinders  18 . Although  FIG. 1  depicts four cylinders (N=4), it can be appreciated that the engine  12  may include additional or fewer cylinders  18 . For example, engines having 4, 5, 6, 8, 10, 12, and 16 cylinders are contemplated. Air flows into the engine  12  through a throttle  20  and is combusted with fuel in the cylinders  18 . 
     The engine  12  includes a fuel injector (not shown) that injects fuel that is combined with the air as it is drawn into the cylinder  18  through an intake port. An intake valve  22  selectively opens and closes to enable the air/fuel mixture to enter the cylinder  18 . The intake valve position is regulated by an intake camshaft  24 . A piston (not shown) compresses the air/fuel mixture within the cylinder  18 . A spark plug  26  initiates combustion of the air/fuel mixture, driving the piston in the cylinder  18 . The piston drives a crankshaft (not shown) to produce drive torque. Combustion exhaust within the cylinder  18  is forced out through an exhaust manifold  28  when an exhaust valve  30  is in an open position. The exhaust valve position is regulated by an exhaust camshaft  32 . The exhaust is treated in an exhaust system (not shown). Although single intake and exhaust valves  22 , 30  are illustrated, it can be appreciated that the engine  12  can include multiple intake and exhaust valves  22 , 30  per cylinder  18 . 
     The vehicle  10  further includes a starter motor  38  and a battery  40 . The starter motor  38  operates in a motor mode. When operating in the motor mode, the starter motor  38  is powered by the battery  40 . The starter motor  38  provides positive torque to assist the engine  12  to turn or crank until the engine  12  can operate under its own power. As can be appreciated, the battery  40  can power other vehicle components in addition to the starter motor  38 . 
     A camshaft position sensor  41  generates a camshaft position signal based on a rotation of either the intake camshaft  24  or the exhaust camshaft  32 , or both. A crankshaft position sensor  42  generates a crankshaft position signal based on a rotation of the crankshaft (not shown). A control module  44  receives the above mentioned signals and detects movement of the engine  12  based one the engine movement detection methods and systems of the present disclosure. The control module  44  then, more properly, performs diagnostic methods based on the engine movement detection methods and systems of the present disclosure. 
     Generally speaking, the engine movement detection methods and systems recognize the relationships between camshaft movement, crankshaft movement, starter motor engagement, and methods for diagnosing the engine. Based on the relationships, the engine movement detection methods and systems determine an operating mode of the engine  12  to be one of, for example, beginning to rotate, producing power, and stopping rotation. Based on the operating mode of the engine, the control module  44  can enable engine diagnostic methods appropriately. For example, the control module  44  can disable the diagnostic methods when the engine  12  is coming to a stop. The control module  44  can perform the diagnostic methods when the engine  12  is starting. The control module  44  can report that the engine  12  is moving when the crankshaft position sensor  42  is not correctly reporting edges. 
     Referring now to  FIG. 2 , a dataflow diagram illustrates various embodiments of an engine movement detection system  46  that may be embedded within the control module  44 . Various embodiments of engine movement detection systems  46  according to the present disclosure may include any number of sub-modules embedded within the control module  44 . As can be appreciated, the sub-modules shown may be combined and/or further partitioned to similarly detect engine movement and diagnose faults. Inputs to the engine movement detection system  46  may be sensed from the vehicle  10  ( FIG. 1 ), received from other control modules (not shown) within the vehicle  10  ( FIG. 1 ), and/or determined by other sub-modules (not shown) within the control module  44 . In various embodiments, the control module of  FIG. 2  includes a movement detection module  50 , a diagnostic module  52 , and a starter control module  54 . 
     The movement detection module  50  receives as input a crankshaft signal  56 , a camshaft signal  58 , an engine speed signal that may be derived from a crankshaft signal  60 , an engine speed that may be derived from camshaft signal  61 , a sync command  62 , and a starter motor status  64 . The movement detection module  50  determines an engine operating mode  66  based on an engine movement detection model  68 . As shown in  FIG. 3 , a state transition diagram illustrates an engine movement detection model  68  that can be implemented within the movement detection module  50  ( FIG. 2 ). The engine movement detection model  68  can include one or more states. Each state can represent a particular operating mode of the engine, for example, the states can be, but are not limited to, ‘assisted spinning’ mode  70 , ‘camshaft and crankshaft stopped’ mode  72 , ‘crankshaft stopped’ mode  74 , ‘un-sustained spinning’ mode  76 , ‘spinning’ mode  78 , and ‘flare’ mode  80 . 
     Transitions between each state are governed by one or more transition conditions. In one example, the state can begin at the ‘camshaft and crankshaft stopped’ mode  72  when the crankshaft signal  56  ( FIG. 2 ) indicates that the crankshaft is not moving and the camshaft signal  58  ( FIG. 2 ) indicates that the camshaft  24  or  32  ( FIG. 1 ) is not moving. The state can transition at  82  from the ‘camshaft and crankshaft stopped’ mode  72  to the ‘assisted spinning’ mode  70  when the crankshaft signal  56  ( FIG. 2 ) indicates that the crankshaft has begun moving or the camshaft signal  58  ( FIG. 2 ) indicates that the camshaft has begun moving. The state can transition at  84  from the ‘assisted spinning’ mode  70  to the ‘flare’ mode  80  when the engine speed derived from crankshaft sensor  60  ( FIG. 2 ) or engine speed derived from the camshaft sensor  61  is greater than an engine speed threshold. Otherwise, the state can transition at  86  back to the ‘camshaft and crankshaft stopped’ mode  72  when both the camshaft signal  58  ( FIG. 2 ) indicates that the camshaft is not moving and the crankshaft signal  56  ( FIG. 2 ) indicates that the crankshaft is not moving. 
     The state can transition at  88  from the ‘flare’ mode  80  to the ‘spinning’ mode  78  when the engine speed derived from crankshaft sensor  60  ( FIG. 2 ) has been above the engine speed threshold for a predetermined amount of time (e.g., greater than a time or count threshold) or a predetermined number of cylinder events. Otherwise, the state can transition at  90  from the ‘flare’ mode  80  back to the ‘assisted spinning’ mode  70  when the engine speed derived from crankshaft sensor  60  ( FIG. 2 ) and the engine speed derived from camshaft sensor  61  drops below the engine speed threshold. 
     The state can transition at  92  from the ‘spinning’ mode  78  to the ‘un-sustained spinning’ mode  76  when the engine speed derived from crankshaft sensor  60  ( FIG. 2 ) and the engine speed derived from camshaft sensor  61  are both less than an engine speed threshold. The state can transition at  94 ,  96 , or  98  from the ‘un-sustained spinning’ mode  76  to one of the ‘spinning’ mode  78 , the ‘crankshaft stopped’ mode  74 , and the ‘camshaft and crankshaft stopped’ mode  72 . For example, the state can transition at  94  from the ‘un-sustained spinning’ mode  76  back to the ‘spinning’ mode  78  when the engine speed derived from crankshaft sensor  60  ( FIG. 2 ) or the engine speed derived from camshaft sensor  61  rises above an engine speed threshold. The state can transition at  96  from the ‘un-sustained spinning’ mode  76  to the ‘crankshaft stopped’ mode  74  when the crankshaft signal  56  ( FIG. 2 ) indicates that the crankshaft is not moving and the “crank sync source command”  62  ( FIG. 2 ) is not disabled. The state can transition at  98  from the ‘un-sustained spinning’ mode  76  to the ‘camshaft and crankshaft stopped’ mode  72  when the “crank sync source command”  62  ( FIG. 2 ) is disabled and the camshaft signal  58  ( FIG. 2 ) indicates that the camshaft is not moving. 
     The state can transition from the ‘crankshaft stopped’ mode  74  to one of the ‘un-sustained spinning’ mode  76 , the ‘assisted spinning’ mode  70 , and the ‘camshaft and crankshaft stopped’ mode  72 . For example, the state can transition at  100  from the ‘crankshaft stopped’ mode  74  to the ‘un-sustained spinning’ mode  76  when the crankshaft signal  56  ( FIG. 2 ) indicates that the crankshaft is now moving. The state can transition at  102  from the ‘crankshaft stopped’ mode to the ‘assisted spinning’ mode when the starter motor  38  is commanded on. The state can transition at  104  from the ‘crankshaft stopped’ mode  74  to the ‘camshaft and crankshaft stopped’ mode  72  when the crankshaft signal  56  ( FIG. 1 ) indicates that the crankshaft is not moving and the camshaft signal  58  ( FIG. 1 ) indicates that the camshaft is not moving. 
     Referring back to  FIG. 2 , the starter control module  54  commands the starter motor  38  ( FIG. 1 ) to run based on the engine operating mode  66 . For example, once the starter motor  38  ( FIG. 1 ) has been commanded on, the starter control module  54  keeps the starter motor  38  ( FIG. 1 ) engaged. The diagnostic module  52  performs one or more engine diagnostic methods based on the starter motor status  64  and the engine operating mode  66 . For example, starter motor engagement is needed to allow the diagnostic module to detect either a fault in the camshaft position sensor  41  or crankshaft position sensor  42 . 
     As can be appreciated, the engine movement detection model operates correctly when either of the crankshaft sensor or camshaft sensor is not available due to a fault. 
     Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present disclosure can be implemented in a variety of forms. Therefore, while this disclosure has been described in connection with particular examples thereof, the true scope of the disclosure should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, specification, and the following claims.