Tangential mixer and method

#This invention relates to internal combustion engines, including but not limited to engines having Exhaust Gas Recirculation (EGR) systems.

#Most internal combustion engines have some type of emission control devices. One type, common to many engines, is recirculation of exhaust gas from an exhaust system to an intake system of the engine. A high pressure EGR system recirculates exhaust gas typically from upstream of a turbine, or other similar device, to downstream of a compressor. Other systems recirculate gas at a low pressure, and are called low-pressure systems. An engine having a high-pressure EGR system has a junction somewhere in the air intake system where EGR gas and intake air mix to form a mixture. The mixture of exhaust gas and intake air is consumed during engine operation.

#Providing each cylinder of an internal combustion engine with a homogeneous mixture of exhaust gas and air is advantageous for operation. A homogeneous mixture promotes efficient operation of the engine because the emission and power output of each cylinder is uniform. The homogeneity of the mixture provided to each cylinder becomes a design parameter of special importance for engines running a considerable amount of EGR over a wide range of engine operating points.

#FIG. 1 is a block diagram of an engine in accordance with the invention.

#FIG. 2A is a front view of a tangential mixer in accordance with the invention.

#FIG. 2B is a side view of the tangential mixture in accordance with the invention.

#The following describes an apparatus for and method of mixing recirculated exhaust gas with intake air in an engine having an EGR system, to yield a homogeneous mixture of exhaust gas and intake air. A tangential flow mixer is placed at a junction where the exhaust gas and intake air meet to effectively mix exhaust gas and intake air and yield a homogeneous mixture. The tangential flow mixer does not increase pressure losses in the intake air system, does not increase fuel consumption and does not lower engine efficiency.

#A block diagram of an engine having a high-pressure EGR system is shown in FIG. 1. A base engine 100 contains a plurality of cylinders housed in an engine block. A compressor 101 is connected to an air cleaner (not shown) and a turbine 103. An outlet of the compressor 101 is connected to a charge cooler 105, which in turn is connected to an intake throttle valve 107. The turbine 103 is connected to an exhaust system 109. The exhaust system 109 is connected to the base engine 100 and to an EGR cooler 111. The EGR cooler 111 is connected to an EGR valve 113. The intake throttle valve 107 and the EGR valve 113 are both connected to a junction 115. The junction 115 is connected to an intake system 117. Finally, the intake system 117 is connected to the base engine 100.

#During engine operation, air from the air cleaner (not shown) enters the compressor 101, and exhaust gas from the base engine 100 enters the exhaust system 109 with a portion going to operate the turbine 103, and a portion entering the EGR cooler 111. The exhaust gas entering a turbocharger through the turbine 111 forces a turbine wheel (not shown) to rotate and provide power to a compressor wheel (not shown) that compresses air. The compressed air travels from the output of the compressor 101 to the charge cooler 105 where it is cooled. The cooled compressed air then goes to the intake throttle valve 107 where its quantity may be controlled, and enters the junction 115.