Abstract:
An automatic shutdown system is provided in which a work vehicle is shutdown upon an occurrence of a critical fault; i.e., an occurrence of a condition which could diminish the life or cause a complete failure of at least a portion of the work vehicle.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to emission control systems in motor vehicles powered by internal combustion engines and, more particularly, vehicles powered by diesel engines with exhaust gas treatment devices requiring regeneration. 
       BACKGROUND OF THE INVENTION 
       [0002]    Diesel particulate filters (DPFs) form a known part of certain diesel engine exhaust gas systems trapping significant amounts of pollutants such as hydrocarbons, carbon monoxide and ash (soot) as the exhaust gas travels through them, i.e., the DPFs. The functional efficiency of a DPF tends to decrease as the amount of pollutants it has entrapped increases. It is, therefore, incumbent on the operator/owner of the vehicle to at least periodically clean or regenerate the DPF. 
         [0003]    DPFs may be regenerated by raising their internal temperatures to temperature values suitable for flashing and flushing the pollutants, i.e., cleaning the DPFs. Such a rise in temperature may be accomplished by increasing the temperature of the exhaust gases passing through the DPFs. In cold conditions, a rise in exhaust gas temperatures may be accomplished by an increased load on the engine. Increasing the volume of exhaust gas throughput may enhance the flushing of such pollutants. Increasing the volume of exhaust gas throughput may enhance the flushing of such pollutants. There are a variety of methods used to increase the temperature of gases flowing through the DPFs. 
         [0004]    Regardless of the method chosen to increase the temperature of the exhaust gas to a threshold level, the regeneration process will, at times, be prolonged. Thus, a need or desire may arise to regenerate a DPF while the operator is away from the machine. 
       SUMMARY OF THE INVENTION 
       [0005]    With a desire for DPF regeneration while the operator is absent from the machine (“unmanned regeneration”), the inventors have recognized a need for the machine to act somewhat as if the operator is present to, among other things, avoid possible damage to the machine should unfavorable operational conditions develop during regeneration. Thus the machine will complete DPF regeneration and follow normal automatic shutdown procedures under normal operating conditions while the machine is parked and will follow immediate shutdown procedures if/when a critical fault occurs during regeneration, critical fault being defined as a condition that could cause damage or undue wear to the machine. A critical fault is, among other things, an occurrence of a detected value that is unfavorable, i.e., that falls outside of an acceptable predetermined range of values, for engine oil pressure, engine coolant temperature or engine coolant level. Such occurrences may lead to a lower life or a complete failure of the engine. Various critical faults are described and illustrated in the specification which follows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is an illustration of a vehicle which may make use of the invention; 
           [0007]      FIG. 2  is schematic of the engine and control system; 
           [0008]      FIG. 3  is an alternative view of the engine and control system with controller  100 ; and 
           [0009]      FIG. 4  is a flowchart illustrating the workings of an embodiment of the invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0010]      FIG. 1  is a side view of a work vehicle, i.e., a loader  10  having an operator cab  20 ; wheels  30  for powered movement along the ground; an engine  40 . Such a work vehicle, as well as others, may be suitable for use of the invention. 
         [0011]      FIG. 2  is a schematic of parts of the vehicle involved in an exemplary embodiment of the invention. Illustrated is a vehicle controller unit (“VCU”)  15  which controls various functions of the vehicle  10 ; an engine  40 ; an engine speed sensor  40   a;  an exhaust  40   b  providing a route for engine exhaust gases; a throttle  41  capable of being engaged and not engaged; a throttle position sensor  41   a  capable of detecting whether the throttle  41  is engaged or not engaged; an engine oil pressure sensor  42   a;  an engine coolant temperature sensor  43 ; an engine coolant level sensor  44 ; an engine controller unit (“ECU”)  45  capable of controlling the functions of the engine  40 ; a transmission  50  capable of being in a forward, a reverse, or a neutral gear; a transmission gear sensor  50   a;  a park brake  55  capable of being engaged and disengaged; a park brake sensor  55   a  capable of detecting if the park brake  55  is engaged or disengaged; an ignition  60  having an on position and an off position through which the vehicle may be powered by an electrical power source  70  which may be a battery, an alternator or some other device when the ignition is in a first position and the vehicle  10  is shutdown when the ignition  60  is in a second position; a diesel particulate filter (“DPF”)  80 ; an exhaust gas temperature sensor  81 ; a fuel dosing injector  82 ; a diesel oxidation chamber (“DOC”)  83 ; and a timer  90  by which the ECU  45  and the VCU  15  measure time passed. 
         [0012]    The vehicle  10  is considered to be in a parked regeneration state, i.e., a state suitable for parked regeneration, when the following conditions exist: (1) the ignition is on; (2) the transmission  50  is in a neutral gear; (3) the park brake  55  is engaged; (4) the engine speed is at standby idle, i.e., the throttle  42  is not engaged; and (5) the DPF soot level is high. The ECU  45  may determine soot level by monitoring exhaust gas temperatures over time and using a lookup table to calculate the difference between soot accumulated over time and soot burned or oxidized over time. Alternatively, the ECU  45  may determine soot level as a mere function of total amount of time the engine has been running since the soot level was determined to be zero (“0”). Regardless of the method, the ECU determines filter soot level. The VCU  15  may allow the vehicle  10  to begin parked regeneration of the DPF  80  when the vehicle  10  is in the parked regeneration state. Parked regeneration may continue as long as the vehicle  10  is in the parked regeneration state. When the state of the vehicle  10  changes, i.e., when one of conditions (1) through (5) (above) do not exist, the VCU  15  may discontinue any ongoing parked regeneration process. An exemplary parked regeneration process will now be described below. 
         [0013]    The exemplary parked regeneration process begins when the vehicle is in a parked regeneration state and the VCU  15  receives a mechanical or electrical signal from the operator of the vehicle  10 , via a switch, to actively clean or regenerate the DPF  80 , i.e., to begin the parked regeneration. The VCU  15  then signals the ECU  45  to begin engine speed management (“ESM”), i.e., to use values transmitted by the exhaust temperature sensor  81  to determine a required engine speed for bringing the exhaust gas temperature to at least a predetermined regeneration temperature which, in this exemplary embodiment, may be at least 275° C. This may allow the DOC  83  to bring exhaust gas temperatures to at least 575° C. prior to the exhaust gas entering the DPF  80 . The fuel dosing injector  82  will inject fuel into the exhaust gas as necessary to bring the additional temperature rise when the exhaust gas enters the DOC  83  for additional burning or oxidation. The ECU  45  then determines the required engine speed via the use of a lookup table cross referencing required engine speeds and exhaust gas temperatures. The ECU  45  then adjusts engine speed to the required engine speed and continues monitoring the exhaust gas temperatures and making adjustments in engine speed using required engine speeds until parked regeneration is complete or canceled. The parked regeneration of the DPF  80  may be normally complete when the ECU  45  determines that the DPF  80  is regenerated and cancels the regeneration signal to the VCU  15 . This determination may be made via the passage of a first predetermined length of time for parked regeneration as measured by the timer  90 . When parked regeneration is complete, the ECU  45  discontinues ESM allowing the engine  40  to return to standby idle speed, i.e., an unthrottled idle speed. Engine coolant may then be allowed to cool down to a first predetermined coolant temperature as detected by the engine coolant temperature sensor  43 . Once the engine coolant has cooled to the first predetermined coolant temperature, the VCU  15  initializes the timer  90  and continues to allow the engine to idle for a second predetermined length of time as measured by the timer  90 . When the timer  90  indicates that the predetermined length of time has passed, the VCU  15  turns the ignition  60  off, shutting down the vehicle  10 . If the vehicle  10  is taken out of the parked regeneration state by the operator via, for example, placing the transmission  50  in a non-neutral gear or making some other demand on the vehicle  10 , i.e., the operator begins to engage the vehicle for locomotion or work operations, the VCU  15  signals the ECU  45  to end ESM, immediately canceling the parked regeneration, and returning the vehicle  10  to normal operation. 
         [0014]    The parked regeneration of the DPF  80  may also be affected by the occurrence of one or more critical faults, i.e., conditions under which the vehicle may be damaged. In this exemplary embodiment, the following may be considered to be critical faults: (a) engine oil pressure falls below a predetermined operational level; (b) engine coolant rises above a second predetermined coolant temperature; and (c) engine coolant level falls below a predetermined coolant level. If a critical fault occurs during a parked regeneration, the VCU  15  signals the ECU  45  to cancel the parked regeneration and turns the ignition off, immediately shutting the vehicle  10  down. 
         [0015]      FIG. 3  illustrates how the sensors, the timer  95  and a warning device  96  may communicate with the controller unit combination  100 . In this exemplary embodiment the warning device  96  may be a monitor, audible sound generator or some other device including a switch and may, among other things, indicate: the vehicle  10  is ready for parked regeneration of the DPF  80 ; the vehicle  10  will/has shut down due to a critical fault; or parked regeneration of the DPF  80  has been canceled due to the vehicle being taken out of the parked regeneration state. 
         [0016]      FIG. 4  illustrates a flowchart that may represent the manner in which this exemplary embodiment works. As illustrated in  FIG. 4 , the entire process begins at step  100  with the ignition  11  and the engine  40  on. If the soot level in the DPF  80  is calculated to be within a predefined range, the warning device  96  may signal the operator that a filter regeneration would be appropriate, at which point the operator manipulates a switch which, in this case is located on the warning device  96 , requesting a parked regeneration. the VCU  15  then signals the ECU  45  to start parked regeneration at step  110 . If the park brake  55  is engaged, a neutral gear is selected, and the throttle is not engaged in steps  120 ,  130  and  140 , the VCU  15  may move to step  160  if engine oil pressure is not less than a predetermined pressure, engine coolant temperature is not greater than a first predetermined temperature, and the coolant level is not less than a predetermined level in steps  150   a,    150   b  and  150   c.  At step  160 , the VCU  15  signals the ECU  45  to begin ESM. At step  170 , the the ECU  45  proceeds to ESM at step  170  and maintains ESM until the time elapsed is greater than or equal to a first predetermined time. Once the time elapsed is greater than or equal to the first predetermined time, ESM is canceled allowing the engine to return to standby idle at step  181 . The timer is restarted at step  182 , to begin a cool down period at step  183  which lasts until the time elapsed is greater than or equal to a second predetermined time at which time the vehicle  10  is shut down. As illustrated, if, at any time, the vehicle  10  moves out of the regeneration state at steps  120 ,  130  and  140 , the VCU  15  signals the ECU  45  to cancel regeneration of the DPF  80  at step  141  and to allow the engine  40  to return to standby idle. Also, if at any time, the oil pressure is less than the predetermined oil pressure, the coolant temperature is greater than the predetermined coolant temperature, or the coolant level is less than the predetermined coolant level at steps  150   a,    150   b,  or  150   c,  the vehicle  10  is shut down at step  190 . 
         [0017]    Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.