A review on the operating characteristics of free piston engine and its recent developments

摘要

Free piston engine (FPE) is a promising alternative to conventional internal combustion engine (ICE) as it has the potential to operate with higher efficiency and produce lower emission. The absence of a crankshaft mechanism is what differs FPE from conventional ICE and provide advantages such as less friction losses and adjustable positions as well as accelerations of its dead centers. However, it also presents problem in starting and control mechanism which conventionally depend highly on crankshaft. Both experimental and simulation studies have been done by different research groups worldwide. The most practical starting process seems to be by applying motoring force at the beginning of the engine operation. While for control, there are several parameters that has significant influence, such as excitation force, damping coefficient, and timing of valve, ignition, as well as injection. Several researches are also in agreement that due to its different motion characteristics near top dead centre (TDC) compared to conventional ICE, FPE tends to have lower emission and heat losses.