The fuel efficiency in the
conventional reciprocal engines is very poor still. This efficiency
supposes in the 4-stroke cycle engine (currently, the most efficient
marketed engine) less to 25% of the total energy produced in the
combustion. But, to obtain this yield it is necessary equip this engine
with a complex and expensive valves train, which limits its elasticity
and consumes a part of the useful output power. The reciprocal motion of
the pistons, (that must be accelerated and decelerated until completely
stopping 2 times in each return of crankshaft), is another reason that
diminishes the output power.
The rotary engine (Wankel) was designed to suppress the previous
disadvantages. In the basic configuration this engine is equipped with a
rotor and a stator. The rotor function is almost similar to the piston.
The movement is rotary (in fact almost rotating), reason why does not
make mass reversion.
In the stator are located two distributed passive ports for the intake
and the exhaust, that replace the valves. Theoretically the rotary
engines would offer a performance very superior to the conventional
reciprocal piston engines, but actually is demonstrated that it is not
thus. This is occasioned mainly by the following causes:
thermodynamic efficiency in the Wankel engine is harmed by the
unfavourable surface / volume ratio of its combustion chamber, that
being long and narrows obstruct the combustion process.
the intake and the exhaust are made without valves, the rotor shape
prevents to optimise the intake / exhaust interaction (overlap),
being harmed the volumetric efficiency about 25%. This provokes
furthermore unstable operation on low rotations regime and high
pollutants emissions. To prevent low volumetric efficiency some
Wankel engines must be aided with turbochargers.
torque is little elastic still.
engine sealed is not as satisfactory yet as in the conventional
engines; being left the compression ratio enough limited still.
Hybrid Engine conjugates the advantages of the conventional pistons engine
with those of the rotary engine, eliminating the main disadvantages of
both. It consists of a 4-stroke engine of positive displacement devised
with rotating and reciprocal technology, reason why it have the advantages
of the rotary engines in relation with its packaging size, power density
and operation simplicity, and the proven reliability and fuel efficiency
of the reciprocal pistons engines. The main advantages are as
mechanical simplicity makes this engine very reliable. The technical level
required for its manufacture is relatively low, because it does not have
parts of difficult mechanization or particular technological processes.
Its final price must be very less to the conventional engine of the same
power. Its maintenance also is simple, being able to be made by
non-specialized workers. Because of these characteristics this engine
is very appropriate as power plant for the future hybrid vehicles and