IMPROVED EXHAUST GAS ENERGY TRANSFER FOR BETTER TURBOCHARGING
Mechanical Engineering Department/Environmental Institute, University of Tehran, Tehran, IRAN
Pulse turbocharging relies heavily on the remaining portion of the power content of pressure pulses, leaving the cylinder of a turbocharged internal combustion engine, which arrive at the entry nozzle of a turbocharger turbine. In this paper a means has been explored and subsequently described that may readily alter the rate at which an exhaust poppet valve of an internal combustion engine opens in order to transfer a larger proportion of exhaust gas energy to the turbocharger turbine. Particular attention is paid to low engine speeds, of a compression ignition engine, when high torque back-up is most needed.
A hydraulic variable valve motion system (Variable Valve Rate, WE) has been developed and a prototype has ultimately been manufactured as a research tool. An experimental flow rig has been designed and constructed to enable both the study of dynamic behavior of the hydraulic WE system in isolation and when used under simulated engine operating conditions. The hydraulic WE system has been successfully used to establish, experimentally, the relationship between rate of exhaust valve opening and exhaust pulse energy with reference to exhaust turbocharging.
Opening the exhaust valve at a higher rate at lower speeds may enhance the pulse power content by approximately 54 percent. This in turn corresponds to an increase from 30 to 70 percent of maximum theoretical available energy transported to the turbocharger turbine entry nozzle ring.