With the world-wide trend to protect the environment, emission legislation is becoming increasingly stringent. The role of cars is being reviewed from the point of the view of preserving the global environment and it has led to the development of vehicles that are environment-friendly. At same time, vehicles are also required with more comfort and better driveability than ever before.
To meet these requirements, usage of turbocharged diesel engines are being increased and recently the variable geometry turbocharger (VGT) such as VNT has received a lot of attention within the automotive industry, as it has the significant benefit of being able to increase engine torque in the low speed region without compromising performance in the high speed region.
Aisin Seiki has now succeeded in developing a novel type of variable turbocharger, called Variable Flow Turbocharger (VFT),which has a very simple structure that overcomes the disadvantages of commercially available VGTs. This report describes the basic construction, principle and characteristic of the VFT, its effect on engine performance, and the results of benchmark tests on state-of-the-art VGT.