Due to the increasing price of fuel, demands for fuel economy of heavy-duty trucks become severer year by year, and many efforts, such as reduction of air drag of vehicle, optimization of transmission and engine performance, improvement of engine combustion, etc., have been taken to meet these demands. However, requirements for the reduction of fuel consumption are expected to become even more critical, so the authors have studied a new design concept for heavy duty truck diesel engines to satisfy these requirements. The basic idea for getting a fuel-economic engine is to make the engine as small as possible and also to apply higher boost turbocharging for obtaining a sufficiently high output. However, measures to improve the undesirable problems which conventional turbocharged engines possess, such as lack of acceleration response and low-speed torque, increase of thermal and mechanical loads, shortage of engine brake torque, poor cold start ability, etc., should also be pursued. A chassis-mounted air-to-air intercooler, inertia-charged air induction system, highly backward-curved impeller of turbocharger, electronically controlled fuel injection timing device, etc., have been applied. And a new design technique as well as new material and construction have also been applied. This engine was installed to a long-haul truck with a gross weight of around 20,000 kg (44,000 lbs) and got better fuel mileage, as expected.
Microstructure and fatigue fracture mechanism for a heavy-duty truck diesel engine crankshaft
