Internal combustion engine

Abstract

The present invention provides an internal combustion engine includes: a turbocharger arranged in exhaust passage; EGR passage branching off from the exhaust passage downstream of a turbine of the turbocharger and connected to intake passage; a burner device arranged in the exhaust passage between the turbine and the portion where the EGR passage branches off to increase exhaust temperature; a bypass passage branching off from the exhaust passage between the turbine and the burner device and connected to the EGR passage; and a bypass valve to adjust flow rate of exhaust gas passing through bypass passage. When flow rate of the exhaust gas is increased, the bypass valve is open, and part of the exhaust gas is guided to the bypass passage. The flow rate of the exhaust gas to be supplied to the burner device is reduced, and the ignition performance of the burner device is ensured.

1 . An internal combustion engine characterized by comprising:
 a turbocharger, arranged in an exhaust passage;   an EGR passage, which branches off from the exhaust passage downstream of a turbine of the turbocharger, and is connected to an intake passage;   a burner device, arranged in the exhaust passage between the turbine and the portion where the EGR passage branches off, to increase exhaust temperature;   a bypass passage, which branches off from the exhaust passage between the turbine and the burner device, and is connected to the EGR passage; and   a bypass valve, to adjust a flow rate of exhaust gas passing through the bypass passage.   
     
     
         2 . The internal combustion engine according to  claim 1 , characterized by further comprising:
 acquisition means, for obtaining the flow rate of exhaust gas discharged by the turbine; and   bypass valve control means, for controlling the bypass valve based on the exhaust gas flow rate obtained by the acquisition means.   
     
     
         3 . The internal combustion engine according to  claim 2 , characterized in that the bypass valve control means opens the bypass valve when the exhaust gas flow rate, obtained by the acquisition means, is greater than a predetermined value, and closes the bypass valve when the exhaust gas flow rate, obtained by the acquisition means, is equal to or smaller than the predetermined value. 
     
     
         4 . The internal combustion engine according to  claim 1 , characterized by further comprising:
 a switching valve, for switching a state of communication between the EGR passage and the bypass passage, and a closed/open state of the EGR passage; and   switching valve control means, for controlling the switching valve,   wherein the switching valve control means controls the switching valve in such a manner that when the bypass valve is closed, communication between the EGR passage and the bypass passage is not established and the EGR passage is open, and when the bypass valve is open, communication between the EGR passage and the bypass passage is established and the EGR passage is closed.   
     
     
         5 . The internal combustion engine according to  claim 1 , characterized by further comprising:
 an EGR valve provided in the EGR passage between a portion where the bypass passage is connected and the intake passage;   a second EGR passage that branches off from the exhaust passage upstream of the turbine of the turbocharger, and is connected to the intake passage;   a second EGR valve arranged in the second EGR passage; and   EGR control means for controlling the EGR valve and the second EGR valve,   wherein the EGR control means closes the EGR valve and opens the second EGR valve when the internal combustion engine is in a predetermined first operating range in a low load side, and opens the EGR valve and closes the second EGR valve when the internal combustion engine is in a predetermined second operating range in a higher load side than the first operating range, and opens the EGR valve when the bypass valve is open, even when the internal combustion engine is in the first operating range.   
     
     
         6 . The internal combustion engine according to  claim 1 , characterized by further comprising:
 an EGR cooler, arranged in the EGR passage between the portion where the bypass passage is connected and the intake passage;   a cooler bypass passage, which bypasses a cooling passage of the EGR cooler;   a cooler switching valve, for switching the passage between the cooling passage and the cooler bypass passage; and   cooler control means, for controlling the cooler switching valve,   wherein the cooler control means controls the cooler switching valve in such a manner that when the bypass valve is closed, the cooling passage is open and the cooler bypass passage is closed, and when the bypass valve is open, the cooling passage is closed and the cooler bypass passage is open.   
     
     
         7 . The internal combustion engine according to  claim 1 , characterized in that the EGR pas sage is connected to the intake passage upstream of a compressor of the turbocharger. 
     
     
         8 . The internal combustion engine according to  claim 2 , characterized in that the acquisition means includes an exhaust gas flow sensor, arranged in the exhaust passage between the turbine and the portion where the bypass passage branches off. 
     
     
         9 . The internal combustion engine according to  claim 1 , characterized in that the burner device includes a fuel addition valve, employed to add fuel to the exhaust passage, and ignition means, for igniting the fuel added through the fuel addition valve. 
     
     
         10 . The internal combustion engine according to  claim 9 , characterized in that the burner device includes at least one of a burner catalyst, for oxidizing the fuel that is added, and an impingement plate, on which the added fuel impinges. 
     
     
         11 . The internal combustion engine according to  claim 1 , characterized by further comprising: an exhaust treatment device, arranged in the exhaust passage downstream of the burner device. 
     
     
         12 . The internal combustion engine according to  claim 11 , characterized in that the exhaust treatment device is located in the exhaust passage between the burner device and the portion where the EGR passage branches off.