Turbocharging systems for internal combustion engines

A method of operating an internal combustion engine with a turbocharger, comprising

• intercepting a flow of exhaust gas from the internal combustion engine,
• directing the flow of exhaust gas for mixing,
• providing a flow of compressed air from said turbocharger for mixing with the exhaust gas,
• mixing the flows of compressed air and exhaust gas in controlled proportions into a mixture of exhaust gas and compressed air,
• controlling the proportions of compressed air and exhaust gas in the mixture by sensing engine speed, determining when the engine is operating below peak torque speed, sensing engine loading, and reducing the proportion of exhaust gas in the mixture as the engine loading increases,
• directing the mixture of exhaust gas and compressed air to the input of a motor-driven compressor, and
• compressing the mixture of exhaust gas and compressed air and directing the resulting compressed mixture as charge air for the internal combustion engine.

An internal combustion engine system, comprising

• an internal combustion engine including an exhaust manifold and an intake manifold;
• a turbo charger having an exhaust gas turbine with an input and an output and charge air compressor with an input and an output;
• a first exhaust gas conduit connecting the exhaust gas turbine input with the exhaust manifold for driving the charge air compressor;
• a motor-drive n compressor having an input and an output;
• a two-input proportioning gas control valve having an output, a first input and a second input connected with the exhaust gas output of the exhaust manifold;
• charge air conduit means connecting the turbocharger charge air compressor, the motor-driven compressor and the first input of the two-input proportioning gas valve in series with the intake manifold of the internal combustion engine, and
• a control, said control operating said two-input proportioning gas control valve to mix in controlled proportions air and exhaust gas from said exhaust manifold for direction to the intake manifold of the internal combustion engine.