Exhaust Filter Regeneration Regime Method and Apparatus

Abstract

An exhaust filter regeneration regime is described in which a filter is regenerated by triggering an exothermic reaction in the filter to burn off particulate load. In order to attain the appropriate regeneration temperatures fuel is injected in the exhaust stream and oxidizes upon contact with a catalytic converter. A control regime comprises metering fuel injection dependent upon exhaust stream temperature to provide a flexible control regime independent of engine duty cycle.

1 . A method of controlling an exhaust filter regeneration regime comprising: 
 injecting fuel into an exhaust stream and thereby increasing an exhaust stream temperature, said increasing exhaust stream temperature being in conjunction with a catalytic treatment element; and    metering fuel injection dependent upon the exhaust stream temperature.    
     
     
         2 . A method as claimed in  claim 1  in which the fuel injecting is metered by controlling one of fuel injection rate, fuel injection pulse duration, amount of fuel injected, fuel injection pressure variation, and injected fuel type variation.  
     
     
         3 . A method as claimed in  claim 1  in which the exhaust stream temperature comprises the temperature of the exhaust stream at an outlet of the catalytic treatment element.  
     
     
         4 . A method as claimed in  claim 3  in which fuel injection is further metered dependent upon the temperature of exhaust gas exiting an engine and the temperature at an inlet of the catalytic treatment element.  
     
     
         5 . A method as claimed in  claim 1  comprising initiating fuel injection into the exhaust stream when the a filter load exceeds an initiation value.  
     
     
         6 . A method as claimed in  claim 1  in which fuel injection is terminated upon any of: a filter load reducing to a predetermined determination threshold, a catalytic treatment element temperature reducing below or exceeding a termination threshold or a regeneration regime period exceeding a time threshold.  
     
     
         7 . A method as claimed in  claim 1  further comprising recording a regeneration regime history and modifying the regeneration regime based on the recorded history.  
     
     
         8 . A method as claimed in  claim 1  further comprising the step of pre-heating fuel to be injected with vehicle waste heat.  
     
     
         9 . A method as claimed in  claim 1  in which fuel is mixed with compressed air in an injection head prior to injection into an exhaust stream.  
     
     
         10 . A method as claimed in  claim 9  in which a supply of fuel to the injection head is terminated a predetermined time prior to a termination of a compressed air supply.  
     
     
         11 . A method of triggering an exhaust filter regeneration regime comprising obtaining a value of filter load as function of a filter pressure and an exhaust mass flow and triggering a regeneration regime when the filter load exceeds a predetermined value.  
     
     
         12 . A method as claimed in  claim 11  comprising the step of initiating fuel injection into an exhaust stream upon the triggering the exhaust filter regeneration regime.  
     
     
         13 . A method of triggering an exhaust filter regeneration regime comprising monitoring filter pressure peak values, identifying when a filter load exceeds a predetermined value from the monitored filter pressure peak values and triggering a regeneration regime.  
     
     
         14 . A method of triggering an exhaust filter regeneration regime in which fuel is injected into an exhaust stream to increase exhaust stream temperature in conjunction with a catalytic treatment element comprising obtaining a value of catalytic treatment element temperature and triggering the regeneration regime when the obtained temperature exceeds a predetermined value.  
     
     
         15 . A method as claimed in  claim 14  further comprising obtaining a value of a filter load as a function of a filter pressure and an exhaust mass flow and triggering the regeneration regime when the filter load exceeds a predetermined value.  
     
     
         16 . A method of controlling an exhaust filter regeneration regime comprising implementing an exhaust stream temperature control strategy, monitoring variation in exhaust stream temperature and at least one control parameter, obtaining a correlation between variation in exhaust stream temperature and the control parameter and adjusting the temperature control strategy based on the collation obtained.  
     
     
         17 . An exhaust filter regeneration apparatus comprising a fuel injector arranged to be mounted in an exhaust stream conduit and a controller for controlling the fuel injector, said fuel injector and said controller being configured to implement an exhaust filter regeneration regime comprising injecting fuel into an exhaust stream and thereby increasing an exhaust stream temperature, said increasing exhaust stream temperature being in conjunction with a catalytic treatment element; and metering fuel injection dependent upon the exhaust stream temperature.  
     
     
         18 . An exhaust filter regeneration apparatus comprising an exhaust stream conduit and a fuel injector mounted therein and arranged to inject fuel in an exhaust stream direction.  
     
     
         19 . An exhaust filter regeneration apparatus as claimed in  claim 18  in which the fuel injector includes a fuel input channel and an air input channel, each said channel having an output end, whereby the output ends of the air and fuel channels are provided adjacent one another at a fuel injection output.  
     
     
         20 . An exhaust filter regeneration apparatus as claimed in  claim 19  in which the fuel input channel is connected to a fuel pump and the air input channel is connected to a compressor.  
     
     
         21 . An exhaust filter regeneration apparatus as claimed in  claim 20  in which said fuel pump is a peristaltic pump.  
     
     
         22 . An exhaust filter regeneration apparatus as claimed in  claim 20  whereby said compressor is arranged to operate in the pressure range of 2 to 200 bar.  
     
     
         23 . An exhaust filter regeneration apparatus as claimed in  claim 17  having an electrical heater located upstream of an exhaust gas input face of the catalytic treatment element relative to an exhaust steam flow.  
     
     
         24 . An exhaust filter regeneration apparatus as claimed in  claim 23  where said electric heater is formed of a catalytic treatment element.  
     
     
         25 . An exhaust filter regeneration apparatus as claimed in any  claim 17  in which the fuel injector draws fuel directly from the a vehicle fuel tank or fuel line.  
     
     
         26 . An exhaust filter regeneration apparatus as claimed in  claim 17  further comprising an exhaust filter component and a sensor extending radially therein.  
     
     
         27 . An exhaust filter regeneration apparatus as claimed in  claim 17  further comprising a fuel conduit configured to provide fuel to the fuel injector in which the fuel conduit is preheated by waste heat.  
     
     
         28 . An engine including an apparatus as claimed in  claim 17 .  
     
     
         29 . A computer program comprising a set of instructions configured to implement an exhaust filter regeneration regime comprising injecting fuel into an exhaust stream and thereby increasing an exhaust stream temperature, said increasing exhaust stream temperature being in conjunction with a catalytic treatment element; and metering fuel injection dependent upon the exhaust stream temperature.  
     
     
         30 . A computer arranged to operate under the instructions of the computer program as claimed in  claim 29 .  
     
     
         31 . An engine control unit configured to implement an exhaust filter regeneration regime comprising injecting fuel into an exhaust stream and thereby increasing an exhaust stream temperature, said increasing exhaust stream temperature being in conjunction with a catalytic treatment element; and metering fuel injection dependent upon the exhaust stream temperature.  
     
     
         32 . A computer readable medium storing a set of instructions to implement an exhaust filter regeneration regime comprising injecting fuel into an exhaust stream and thereby increasing an exhaust stream temperature, said increasing exhaust stream temperature being in conjunction with a catalytic treatment element; and metering fuel injection dependent upon the exhaust stream temperature.  
     
     
         33 . A method of controlling exhaust, comprising: 
 increasing an exhaust stream temperature;    controlling said increasing an exhaust stream temperature in conjunction with a catalytic treatment element; and    metering fuel injection dependent upon said exhaust stream temperature.    
     
     
         34 . An apparatus for controlling exhaust, comprising: 
 means for increasing an exhaust stream temperature;    means for controlling said increasing an exhaust stream temperature in conjunction with a catalytic treatment element; and    means for metering fuel injection dependent upon said exhaust stream temperature.