Exhaust gas purification device for internal combustion engine

Abstract

An exhaust gas purification device of a diesel engine having a DPF (diesel particulate filter) for collecting particulate matters such as soot and unburned components from exhaust gas of the diesel engine calculates an oil dilution quantity as a quantity of fuel diluting engine oil from a regeneration time of the DPF and an operation state. The exhaust gas purification device alleviates an increase in the oil dilution quantity by using a regeneration device that causes the oil dilution quantity less than the oil dilution quantity caused by another regeneration device when the oil dilution quantity exceeds a predetermined value. Thus, both of suppression of the oil dilution quantity and inhibition of deterioration of fuel consumption due to post-injection can be achieved.

1 . An exhaust gas purification device of an internal combustion engine having a diesel particulate filter for collecting particulate matters contained in exhaust gas of the engine, the exhaust gas purification device comprising:
 a controller that controls operation of the exhaust gas purification device;   a particulate matter deposition quantity measurement section that measures a deposition quantity of the particulate matters in the diesel particulate filter;   a particulate matter deposition quantity determination device that determines whether the deposition quantity of the particulate matters measured by the particulate matter deposition quantity measurement section is greater than a first predetermined value;   an oil dilution related data measurement device that measures oil dilution related data necessary for deriving an oil dilution quantity as a quantity of fuel diluting engine oil;   an oil dilution related data determination device that determines whether the oil dilution related data measured by the oil dilution related data measurement device is greater than a second predetermined value; and   a regeneration device that combusts the particulate matters to regenerate the diesel particulate filter, the regeneration device including a first regeneration device and a second regeneration device, which causes the oil dilution quantity less than the oil dilution quantity cause by the first regeneration device and causes a fuel consumption rate greater than the fuel consumption rate caused by the first regeneration device, wherein   the controller has a selection device,   the selection device selects the first regeneration device from the two regeneration devices when the particulate matter deposition quantity determination device determines that the particulate matters greater than the first predetermined value in quantity are deposited in the diesel particulate filter and the oil dilution related data determination device determines that the measured oil dilution related data is lower than the second predetermined value, and   the selection device selects the second regeneration device from the two regeneration devices when the particulate matter deposition quantity determination device determines that the particulate matters greater than the first predetermined value in quantity are deposited in the diesel particulate filter and the oil dilution related data determination device determines that the measured oil dilution related data is higher than the second predetermined value.   
   
   
       2 . The exhaust gas purification device as in  claim 1 , wherein
 the first regeneration device performs post-injection for injecting the fuel in an expansion stroke, and   the second regeneration device performs the post-injection at injection timing advanced from injection timing in the case of the first regeneration device in the expansion stroke.   
   
   
       3 . The exhaust gas purification device as in  claim 1 , wherein
 the post-injection is performed as a plurality of injections performed in a plurality of times during the expansion stroke.   
   
   
       4 . The exhaust gas purification device as in  claim 1 , wherein
 the oil dilution related data measurement device measures the oil dilution related data from vehicle speed and a travel distance in a period in which the first regeneration device or the second regeneration device is operated or from the vehicle speed and a travel time in a period in which the first regeneration device or the second regeneration device is operated.   
   
   
       5 . The exhaust gas purification device as in  claim 1 , wherein
 the oil dilution related data measurement device measures the oil dilution related data from a duration in which the first regeneration device or the second regeneration device is operated.   
   
   
       6 . The exhaust gas purification device as in  claim 1 , wherein
 the oil dilution related data measurement device derives the oil dilution related data from a difference between the oil dilution quantity and an oil evaporation quantity as a quantity of the fuel evaporating from the oil.