Comparative Investigation of Throttle-free Load Control on a 2.0 l Four Cylinder Turbocharged Gasoline Engine with Port and Direct Fuel Injection

A 2.0 l turbocharged gasoline engine with port injection and a comparable turbocharged gasoline engine with direct injection have been investigated on a test bench at Kaiserslautern Technical University. Both engines were driven with throttle-free load control by fully mechanically variable valve actuation (CVVL). The basic series-production turbocharged engine in this comparison is the version with direct injection without the fully variable valve train. The focuses of the fired tests were investigation of the fuel consumption at part load and of maximum torque behavior at low engine speeds at full load. In both engine modes, use of fully variable valve actuation shows improvements compared with the turbocharged engine versions without CVVL. Better turbocharger response enabled the torque behavior to be optimized. The turbocharged engine with port injection and CVVL matches the torque of the basic turbocharged engine with direct injection and at low engine speeds exceeds the torque of the basic engine. The highest torque at full load and low engine speeds can be obtained with the CVVL turbocharged engine in the direct injection mode. The CVVL turbocharged gasoline engine with port injection shows the highest potential to reduce fuel consumption in this comparative investigation.