Abstract:
A method of operating an internal combustion engine with a variable geometry turbocharger whereby the turbocharger is cleaned of accumulated soot on a time based periodic basis.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation-in-Part which claims the benefit of U.S. application Ser. No. 11/958,449, filed Dec. 18, 2007, which is hereby incorporated by reference in full. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method for cleaning a turbocharger vane assembly of accumulated soot on a periodic basis. 
     The present invention further relates to a method of operating an internal combustion engine with an electronic central unit having memory and a turbocharger, preferably a variable geometry turbocharger, wherein the VGT is cycled according to engine operation status to effect cleaning of the turbocharger vane on a regular periodic basis as set by a timer in the ECU. The timer may be reset every ignition cycle. 
     2. Description of the Related Art 
     Miller et al., U.S. Pat. No. 4,548,040 is the most pertinent to this invention. Specifically, Miller et al. &#39;047 discloses a method and apparatus for determining when to initiate the cleaning of turbine blades of a turbocharger. The performance of the compressor portion of the turbocharger is monitored and upon a degradation and performance being detected, it is indicated that the fouling of the turbine blade has occurred. In response to this indication a water injection system is energized for supplying atomized water under high pressure to the exhaust gas powering the turbocharger to effectively clean the turbine blades. Means are provided for decreasing the speed of the turbocharger after the cleaning cycle to allow for an effective cleaning process. Miller et al. &#39;040 discloses the use of a nozzle to inject water on the turbine blades in order to effect cleaning. 
     SUMMARY OF THE INVENTION 
     The present invention is a method for determining necessity of multiple vane cleaning procedures in a turbocharger subjected to exhaust gasses. In one aspect, the method comprises using sensor data signals to determine whether the effort required to cycle the turbocharger exceeds a predetermined threshold, thereby indicating that at least one vane is fouled with exhaust gas soot, and then cycling the turbocharger by running it at a predetermined speed for a predetermined number of times until the effort required to cycle the turbocharger is at least equal to or below a predetermined threshold. If after cycling a predetermined number of times, the effort to cycle the turbocharger exceeds a predetermined threshold, a warning is activated and the operator of the engine is alerted. If the turbocharger is a variable geometry turbocharger, the vanes may be positioned from a first operating position to a second operating position to effect cleaning of the vanes, after which they are returned to the first operating position for normal engine operation. In this regard, the second operating position may be a predetermined position of the vane to facilitate cleaning of the vane during cycling. Irrespective of the kind of turbocharger involved, the cycle of the turbocharger may be in the range of up to 8000 rpm to effect cleaning of the vanes. 
     The present invention further relates to a method to operate an electronic controlled internal combustion engine, preferably a diesel engine, equipped with an electronic control unit having memory, and further equipped with a variable geometry turbocharger assembly including a motor to cycle the turbocharger, exposed to exhaust emissions to effect cleaning of the turbocharger vanes which are positioned in an actuator. The method comprises determining the effort to cycle a vane mechanism in said turbocharger exceeds a predetermined threshold based upon engine operation state. The turbocharger motor effort is described by the mathematical structure: 
     
       
         
           
             
               ∑ 
               
                  
                 F 
                  
               
             
             n 
           
         
       
     
     Wherein: 
     F is motor effort and 
     n is number of times of sampling of vane actuator difficulty. 
     When it is determined to cycle the turbocharger, the vanes are positioned in the actuator conducive to cleaning. The turbocharger is cycled based upon engine torque and time period for cycling, a determination is made whether the effort to cycle the turbocharger exceeds a predetermined effort based upon predetermined effort levels based upon engine operation, and the turbocharger is repeatedly cycled a predetermined number of times based upon effort. The engine is operated according to the present invention at either idle, or in Power Take Off (PTO) mode and idle. In any event, it is preferred that the engine is operated in a steady state prior to initiating a vane cleaning cycle. Preferably, during the cycling effort, the engine throttle is in full open position and the EGR valve is in a full closed position. In addition, engine fuel and ignition may be altered based upon a number of weighting factors, and the engine diagnostics based upon air flow, boost pressure and plausibility checks is disabled. In addition, the engine may be provided with a timer to determine the time and number of cycles that are predetermined for cycling to occur. The timer may be reset if the diesel engine is regenerating the diesel particulate filter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic representation of an ECU controlled internal combustion engine equipped with a variable geometry turbocharger. 
         FIG. 2A  is a representation of one type of variable geometry turbocharger useful in the present invention. 
         FIG. 2B  is a representation of turbocharger in  FIG. 2A  with the vanes turned; 
         FIG. 3  is a schematic representation of another variable geometry turbocharger useful in the present invention; 
         FIG. 4A and 4B  are schematic graphic representations of the change in vane output according to the present invention; 
         FIG. 5  is a schematic representation of a software flowchart of one method according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  illustrates a vehicle powertrain system  10  in accordance with one non-limiting aspect of the present invention. The system  10  may provide power for driving any number of vehicles, including on-highway trucks, construction equipment, marine vessels, stationary generators, automobiles, trucks, tractor-trailers, boats, recreational vehicle, light and heavy-duty work vehicles, and the like. 
     The system  10  may be referred to as an internal combustion driven system wherein fuels, such as gasoline and diesel fuels, are burned in a combustion process to provide power, such as with a spark or compression ignition engine  14 . The engine  14  may be a diesel engine that includes a number of cylinders  18  into which fuel and air are injected for ignition as one skilled in the art will appreciate. The engine  14  may be a multi-cylinder compression ignition internal combustion engine, such as a 4, 6, 8, 12, 16, or 24 cylinder diesel engines, for example. It should be noted, however, that the present invention is not limited to a particular type of engine or fuel. 
     Exhaust gases generated by the engine  14  during combustion may be emitted through an exhaust system  20 . The exhaust system  20  may include any number of features, including an exhaust manifold and passageways to deliver the emitted exhaust gases to a particulate filter assembly  30 , which in the case of diesel engines is commonly referred to as a diesel particulate filter. Optionally, the system  20  may include a turbocharger proximate the exhaust manifold for compressing fresh air delivery into the engine  14 . The turbocharger, for example, may include a turbine  32  and a compressor  34 , such as a variable geometry turbocharger (VGT) and/or a turbo compound power turbine. Of course, the present invention is not limited to exhaust systems having turbochargers or the like. 
     The particulate filter assembly  30  may be configured to capture particulates associated with the combustion process. In more detail, the particulate filter assembly  30  may include an oxidation catalyst (OC) canister  36 , which in includes an OC  38 , and a particulate filter canister  42 , which includes a particulate filter  44 . The canisters  36 ,  42  may be separate components joined together with a clamp or other feature such that the canisters  36 ,  42  may be separated for servicing and other operations. Of course, the present invention is not intended to be limited to this exemplary configuration for the particulate filter assembly  30 . Rather, the present invention contemplates the particulate filter assembly including more or less of these components and features. In particular, the present invention contemplates the particulate filter assembly  30  including only the particulate filter  44  and not necessarily the OC canister  36  or substrate  38  and that the particulate filter  44  may be located in other portions of the exhaust system  20 , such as upstream of the turbine  32 . 
     The OC  38 , which for diesel engines is commonly referred to as a diesel oxidation catalyst, may oxidize hydrocarbons and carbon monoxide included within the exhaust gases so as to increase temperatures at the particulate filter  44 . The particulate filter  44  may capture particulates included within the exhaust gases, such as carbon, oil particles, ash, and the like, and regenerate the captured particulates if temperatures associated therewith are sufficiently high. In accordance with one non-limiting aspect of the present invention, one object of the particulate filter assembly  30  is to capture harmful carbonaceous particles included in the exhaust gases and to store these contaminates until temperatures at the particulate filter  44  favor oxidation of the captured particulates into a gas that can be discharged to the atmosphere. 
     The OC and particulate filter canisters  36 ,  42  may include inlets and outlets having defined cross-sectional areas with expansive portions there between to store the OC  38  and particulate filter  44 , respectively. However, the present invention contemplates that the canisters  36 ,  42  and devices therein may include any number configurations and arrangements for oxidizing emissions and capturing particulates. As such, the present invention is not intended to be limited to any particular configuration for the particulate filter assembly  30 . 
     To facilitate oxidizing the capture particulates, a doser  50  may be included to introduce fuel to the exhaust gases such that the fuel reacts with the OC  38  and combusts to increase temperatures at the particulate filter  44 , such as to facilitate regeneration. For example, one non-limiting aspect of the present invention contemplates controlling the amount of fuel injected from the doser as a function of temperatures at the particulate filter  44  and other system parameters, such as air mass flow, EGR temperatures, and the like, so as to control regeneration. However, the present invention also contemplates that fuel may be included within the exhaust gases through other measures, such as by controlling the engine  14  to emit fuel with the exhaust gases. 
     An air intake system  52  may be included for delivering fresh air from a fresh air inlet  54  through an air passage to an intake manifold for introduction to the engine  14 . In addition, the system  52  may include an air cooler or charge air cooler  56  to cool the fresh air after it is compressed by the compressor  34 . Optionally, a throttle intake valve  58  may be provided to control the flow of fresh air to the engine  14 . Optionally, the throttle intake valve  58  may also be provided to control the flow of EGR gases to the engine  14  or control both fresh air and EGR gases  64  to the engine  14 . The throttle valve  58  may be a manually or electrically operated valve, such as one which is responsive to a pedal position of a throttle pedal operated by a driver of the vehicle. There are many variations possible for such an air intake system and the present invention is not intended to be limited to any particular arrangement. Rather, the present invention contemplates any number of features and devices for providing fresh air to the intake manifold and cylinders, including more or less of the foregoing features. 
     An exhaust gas recirculation (EGR) system  64  may be optionally provided to recycle exhaust gas to the engine  14  for mixture with the fresh air. The FUR system  64  may selectively introduce a metered portion of the exhaust gasses into the engine  14 . The EGR system  64 , for example, may dilute the incoming air charge and lower peak combustion temperatures to reduce the amount of oxides of nitrogen produced during combustion. The amount of exhaust gas to be recirculated may be controlled by controlling an EGR valve  66  and/or in combination with other features, such as the turbocharger. The EGR valve  66  may be a variable flow valve that is electronically controlled. There are many possible configurations for the controllable EGR valve  66  and embodiments of the present invention are not limited to any particular structure for the EGR valve  66 . 
     The EGR system  64  in one non-limiting aspect of the present invention may include an EGR cooler passage  70 , which includes an EGR cooler  72 , and an EGR cooler bypass  74 . The EGR valve  66  may be provided at the exhaust manifold to meter exhaust gas through one or both of the EGR cooler passage  70  and bypass  74 . Of course, the present invention contemplates that the EGR system  64  may include more or less of these features and other features for recycling exhaust gas. Accordingly, the present invention is not intended to be limited to any one EGR system and contemplates the use of other such systems, including more or less of these features, such as an EGR system having only one of the EGR cooler passage or bypass. 
     A cooling system  80  may be included for cycling the engine  14  by cycling coolant there through. The coolant may be sufficient for fluidly conducting away heat generated by the engine  14 , such as through a radiator. The radiator may include a number of fins through which the coolant flows to be cooled by air flow through an engine housing and/or generated by a radiator fan directed thereto as one skilled in the art will appreciated. It is contemplated, however, that the present invention may include more or less of these features in the cooling system  80  and the present invention is not intended to be limited to the exemplary cooling system described above. 
     The cooling system  80  may operate in conjunction with a heating system  84 . The heating system  84  may include a heating core, a heating fan, and a heater valve. The heating core may receive heated coolant fluid from the engine  14  through the heater valve so that the heating fan, which may be electrically controllable by occupants in a passenger area or cab of a vehicle, may blow air warmed by the heating core to the passengers. For example, the heating fan may be controllable at various speeds to control an amount of warmed air blown past the heating core whereby the warmed air may then be distributed through a venting system to the occupants. Optionally, sensors and switches  86  may be included in the passenger area to control the heating demands of the occupants. The switches and sensors may include dial or digital switches for requesting heating and sensors for determining whether the requested heating demand was met. The present invention contemplates that more or less of these features may be included in the heating system and is not intended to be limited to the exemplary heating system described above. 
     A controller  92 , such as an electronic control module or engine control module, may be included in the system  10  to control various operations of the engine  14  and other system or subsystems associated therewith, such as the sensors in the exhaust, EGR, and intake systems. Various sensors may be in electrical communication with the controller via input/output ports  94 . The controller  92  may include a microprocessor unit (MPU)  98  in communication with various computer readable storage media via a data and control bus  100 . The computer readable storage media may include any of a number of known devices which function as read only memory  102 , random access memory  104 , and non-volatile random access memory  106 . A data, diagnostics, and programming input and output device  108  may also be selectively connected to the controller via a plug to exchange various information therebetween. The device  108  may be used to change values within the computer readable storage media, such as configuration settings, calibration variables, instructions for EGR, intake, and exhaust systems control and others, 
     The system  10  may include an injection mechanism  114  for controlling fuel and/or air injection for the cylinders  18 . The injection mechanism  114  may be controlled by the controller  92  or other controller and comprise any number of features, including features for injecting fuel and/or air into a common-rail cylinder intake and a unit that injects fuel and/or air into each cylinder individually. For example, the injection mechanism  114  may separately and independently control the fuel and/or air injected into each cylinder such that each cylinder may be separately and independently controlled to receive varying amounts of fuel and/or air or no fuel and/or air at all. Of course, the present invention contemplates that the injection mechanism  114  may include more or less of these features and is not intended to be limited to the features described above. 
     The system  10  may include a valve mechanism  116  for controlling valve timing of the cylinders  18 , such as to control air flow into and exhaust flow out of the cylinders  18 . The valve mechanism  116  may be controlled by the controller  92  or other controller and comprise any number of features, including features for selectively and independently opening and closing cylinder intake and/or exhaust valves. For example, the valve mechanism  116  may independently control the exhaust valve timing of each cylinder such that the exhaust and/or intake valves may be independently opened and closed at controllable intervals, such as with a compression brake. Of course, the present invention contemplates that the valve mechanism may include more or less of these features and is not intended to be limited to the features described above. 
     In operation, the controller  92  receives signals from various engine/vehicle sensors and executes control logic embedded in hardware and/or software to control the system  10 . The computer readable storage media may, for example, include instructions stored thereon that are executable by the controller  92  to perform methods of controlling all features and sub-systems in the system  10 . The program instructions may be executed by the controller in the MPU  98  to control the various systems and subsystems of the engine and/or vehicle through the input/output ports  94 . In general, the dashed lines shown in  FIG. 1  illustrate the optional sensing and control communication between the controller and the various components in the powertrain system. Furthermore, it is appreciated that any number of sensors and features may be associated with each feature in the system for monitoring and controlling the operation thereof. 
     In one non-limiting aspect of the present invention, the controller  92  may be the DDEC controller available from Detroit Diesel Corporation, Detroit, Mich. Various other features of this controller are described in detail in a number of U.S. patents assigned to Detroit Diesel Corporation. Further, the controller may include any of a number of programming and processing techniques or strategies to control any feature in the system  10 . Moreover, the present invention contemplates that the system may include more than one controller, such as separate controllers for controlling system or sub-systems, including an exhaust system controller to control exhaust gas temperatures, mass flow rates, and other features associated therewith. In addition, these controllers may include other controllers besides the DDEC controller described above. 
     In accordance with one non-limiting aspect of the present invention, the controller  92  or other feature may be configured for permanently storing emission related fault codes in memory that is not accessible to unauthorized service tools. Authorized service tools may be given access by a password and in the event access is given, a log is made of the event as well as whether any changes that are attempted to made to the stored fault codes. It is contemplated that any number of faults may be stored in permanent memory, and that preferably eight such faults are stored in memory. 
       FIGS. 2A and 2B  are a close-up schematic representation of one type of variable geometry turbocharger useful in the present invention. Specifically, variable geometry turbocharger  118  has a plurality of pivotably adjustable vanes  120  from a close position  122  to an open position  124 . The vanes are adjusted by an electric motor  126  comprised of a housing  128  with an armature in the housing (not shown). The rotational movement of the motor causes linkage  130  to impart force  131  to ring  136  to cause it to rotate in direction  135  about the perimeter  138  of the turbocharger. The vanes are pivotably attached at  137  via linkage  139  to the ring and are moved pivotably about their longitudinal axis  140  to change position from a low vane output position  142  to a high vane output position  144 . The amount of movement of the vanes from a normal operation to a low output position and a high output position are of equal quantities and opposite to each other relative to normal position. To vary the vane output, the vanes are pivotably adjusted an equal and opposite amount relative normal operation in order to reach low output and high output. 
       FIG. 3  is a schematic representation of another variable geometry turbocharger  148  having a nozzle ring  150  with apertures  152  that are slightly larger and accommodate vanes  154  of turbocharger  148 . The nozzle ring is movable relative the vanes in directions  156 ,  158  by means of an electric motor that is similar in construction to that described in relation to  FIGS. 2A and 2B . It differs from  FIGS. 2A and 2B  because the rotation of the motor moves the nozzle ring in the direction  156  and  158  to clean soot from the vanes by the physical action of the operative against the vanes to remove the soot from the vanes. Because the soot is deposited onto the vanes, it exerts a resistance to the movement of the ring. The resistance of the soot laden vanes to the movement of the ring results in an increased effort by the motor to move the ring to vary the vane output. The work is seen as an increase in effort, described by the mathematical structure: 
     
       
         
           
             
               ∑ 
               
                  
                 F 
                  
               
             
             n 
           
         
       
     
     Wherein: 
     F is motor effort and 
     n is number of times of sampling of vane actuator difficulty. 
     Vane output is modified by moving the nozzle ring relative its position during normal operation of the turbocharger. Relative the normal operating position, the nozzle ring may be moved in a distance to a larger vane output position and in an apposite but equal distance to a low vane output position, 
       FIGS. 4A and 4B  are schematic graphic representations of the change in vane out according to the present invention. Axis  160  is the percent of vane output and axis  162  in time. Normal vane output, corresponding to normal turbocharger operation is represented at  164 . During cycling, the vane output is charged within predetermined absolute values  166  and  168 , respectively. Valve  166  represents the highest vane output and valve  168  represents the lowest vane output. During cycling the turbocharger vane output is cycled from high to low and then resumes normal output at some point in time. 
       FIG. 4B  is a representation of an actual operation of a variable geometry turbocharger according to the present invention. The normal operational status is represented at  170 , which shows normal mines fluctuating in vane output. During cycling, vane output is changed by a value +Δ to the high vane output represented at  172 . The low vane output is changed relative normal operation by a value −Δ. Note that +Δ and −Δ are the same quantity but opposite or negative each other relative to normal engine operations. 
       FIG. 5  is a schematic representation of a software flow charge of one method  176  according to the present invention. Step  178  is determining the operation status of the engine and simultaneously determining the operational status of the turbocharger. In determining the operational status of the engine, the ECM simultaneously determines whether the ignition is on, which the engine is operating in idle, Power Take Off, or idle and Power Take Off, whether the engine is in regeneration made for some aspect of the exhaust components, such as whether the engine is dosing fuel into diesel particulate filter in the case of a compression ignition engine during diesel particulate filter regeneration, whether the engine torque exceeds a predetermined calibratable limit valve, whether the engine speed or RPM exceeds a predetermined calibratable limit. In addition, the turbocharger operational status is determined simultaneously. The ECM determines whether the vanes are steady and whether there are any turbocharger faults. All the actions in step  178  proceed simultaneously within a predetermined calibratable time period. If any one of these determinations is counter to valve cleaning, the method stops and normal turbocharger operation continues, as seen at step  180 . 
     Step  182  is optional, and access only if all determinations in step  178  are favorable and compatible with vane cleaning. Step  182  includes the simultaneous action of closing the EGR valve, opening the intake throttle adjusting engine timing and adjusting fueling. 
     Step  184  is cycling the vanes to clean them of soot. In this step, the output of the vanes is cycled from a high output vane to a low output vane relative to normal output vane as previously described in relation to  FIGS. 2A through 4B . The vanes are cycled for a predetermined calibratable period of time and the engine resumes normal operation as indicated at step  182  and the timer is reset. In step  186 , the work of the electric motor is measured, according to the mathematical structure: 
     
       
         
           
             
               ∑ 
               
                  
                 F 
                  
               
             
             n 
           
         
       
     
     Wherein: 
     F is motor effort and 
     n is number of times of sampling of vane actuator difficulty. 
     If it is determined that there is no limit, step  188  is return to normal turbocharger operation and reset the time. If it is determined that there is a limit, step  190  is determining whether the maximum number of vane cycles has been met. If yes, the software loops back to step  188 . If no, the software loops back to step  184 . 
     The words used to describe this invention are words of description, and not words of limitation. Those skilled in the art recognize that many variations and modifications are possible without departing from the scope and spirit of the invention as set forth in the appended claims.