Exhaust gas recirculation system for turbo charged engines

Claim 1

In a turbocharged engine system comprising a piston - type engine with inlet manifold means, exhaust manifold means, turbine means arranged to be driven by exhaust gases from said exhaust manifold means and transmit a portion of the energy from said exhaust gases to drive compressor means between gas intake means and said inlet manifold means, an improvement wherein: said exhaust manifold means comprises a first exhaust manifold receiving exhaust gases only from a first set of one or more pistons and a second exhaust manifold receiving exhaust gases only from a second set of one or more pistons; said turbine means comprises a first turbine driven by exhaust gases from said first exhaust manifold; said compressor means comprises a first compressor driven by said first turbine; and said system includes means for recycling a portion of the exhaust gases from said second exhaust manifold to said inlet means; and including means for sensing pressure in said inlet manifold means and also including, intermediate said second exhaust manifold and said inlet manifold means, pressure control valve means which open and close said recycling means to exhaust responsive to pressure in said inlet manifold means, as sensed by said pressure sensing means, for stabilizing pressure in said recycling means at a value higher than pressure in said inlet manifold means.