Fresh Air Bypass to Cool Down Hot Exhaust in DPF Regeneration Mode at Low Vehicle Speed and Idle

Abstract

An engine system includes a diesel engine having an exhaust manifold connected to the diesel engine. An exhaust passage is connected to the exhaust manifold and a diesel particulate filter is disposed in the exhaust passage. An air intake passage is provided for supplying fresh air to the diesel engine. A bypass passage is connected between the air intake passage and the exhaust passage in a location downstream of the diesel particulate filter. The bypass passage includes a bypass control valve for opening and closing the bypass passage during a diesel particulate filter regeneration cycle when the vehicle is at low speed or idle.

1 . An engine system, comprising:
 a diesel engine;   an exhaust passage in communication with an exhaust gas from the diesel engine;   a diesel particulate filter disposed in the exhaust passage;   an air intake passage for supplying air to the diesel engine; and   a bypass passage connected between the air intake passage and the exhaust passage at a location downstream of the diesel particulate filter, the bypass passage including a bypass control valve for opening and closing the bypass passage.   
     
     
         2 . The engine system of  claim 1 , further comprising a turbocharger that provides compressed air to the air intake passage. 
     
     
         3 . The engine system according to  claim 2 , wherein the turbocharger provides the compressed air to a charger cooler, the bypass passage being connected to the air intake passage downstream of the charger cooler. 
     
     
         4 . The engine system according to  claim 2 , wherein the turbocharger provides the compressed air to a charger cooler, the bypass passage being connected to the air intake passage downstream of the turbocharger and upstream of the charger cooler. 
     
     
         5 . The engine system of  claim 2 , wherein the compressed air is provided to the bypass passage, the compressed air being at a pressure that is greater than a pressure of exhaust gas in the exhaust gas passage at the location downstream of the diesel particulate filter. 
     
     
         6 . The engine system according to  claim 1 , wherein the air intake passage includes an intake throttle valve downstream of the bypass passage. 
     
     
         7 . The engine system according to  claim 1 , further comprising an engine controller for periodically operating the engine system in a diesel particulate filter regeneration mode and for opening the bypass control valve during the diesel particulate filter regeneration mode. 
     
     
         8 . The engine system according to  claim 1 , further comprising an engine controller for periodically operating the engine system in a diesel particulate filter regeneration mode and for opening the bypass valve when the engine is in the diesel particulate filter regeneration mode and the engine is at idle. 
     
     
         9 . The engine system according to  claim 1 , further comprising an engine controller for periodically operating the engine system in a diesel particulate filter regeneration mode and for causing the bypass valve to open when the engine is in the diesel particulate filter regeneration mode and the engine is driving a vehicle at a speed of 5 miles per hour or less. 
     
     
         10 . An exhaust treatment system for an engine, comprising:
 an exhaust passage adapted to be connected to the engine;   a diesel particulate filter disposed in the exhaust passage;   an air intake passage adapted for supplying air to the engine;   a bypass passage connected between the air intake passage and the exhaust passage at a location downstream of the diesel particulate filter, the bypass passage including a bypass control valve for opening and closing the bypass passage.   
     
     
         11 . The exhaust treatment system according to  claim 10 , further comprising a turbocharger that provides compressed air to the air intake passage 
     
     
         12 . The exhaust treatment system according to  claim 11 , wherein said turbocharger provides the compressed air to a charger cooler, the bypass passage being connected to the air intake passage downstream of the charger cooler. 
     
     
         13 . The exhaust treatment system according to  claim 11 , wherein the turbocharger provides the compressed air to a charger cooler, the bypass passage being connected to the air intake passage downstream of the turbocharger and upstream of the charger cooler. 
     
     
         14 . The exhaust treatment system according to  claim 11 , wherein the compressed air is provided to the bypass passage, the compressed air being at a pressure that is greater than a pressure of exhaust gas in the exhaust gas passage at the location downstream of the diesel particulate filter. 
     
     
         15 . The exhaust treatment system according to  claim 10 , wherein the air intake passage includes an intake throttle valve downstream of the bypass passage. 
     
     
         16 . A method comprising:
 regenerating a diesel particulate filter that is in communication with an exhaust gas from a diesel engine; and   providing communication between an intake air source and the exhaust gas at a location downstream of the diesel particulate filter during the regenerating.   
     
     
         17 . The method of  claim 16 , further comprising compressing air supplied to the intake air source and providing the compressed air to the location downstream of the diesel particulate filter.