Advantages for a four-stroke engine with compression
ignition means.
- higher volumetric efficiency ;
- higher specific output ;
- lower losses
due to mechanical friction ;
- engine accommodation
to the cetane number ;
- accurate
definition of an ideal temperature at the end of the compression
phase, so to provide suitable self-ignition of the fuel in all circumstances
( from cold starting to high supercharging pressures ) ;
- better engine
performance at high altitudes ;
- lower emissions
of hydrocarbons and nitrogen oxide in the exhaust gases.
Advantages for a four-stroke engine with spark
ignition means.
-
higher volumetric efficiency ;
- higher specific
output ;
- lower losses
due to mechanical friction and pumping ;
- higher partial-load
effeciency of the engine, due to a higher compression ratio proportionally
to the depression in the intake pipe (closing of the throttle valve)
;
- engine accomodation
to the octane number ;
- better engine
performance at high altitudes ;
- better air-fuel
mixture homogeneity ;
- lower emmissions
of carbon monoxide, nitrogen oxides and hydrocarbons in the exhaust
gases.
Advantages and conditions of use of the four-stroke
engine with compression ignition means and high supercharging pressure
levels, mounted in road haulage tractors.
The reduction of the displacement of each cylinder
of the engine, based on the mean piston speed, permits an increase
in the speed of the engine and a consistent decrease in low frequencies.
A higher gear reduction on the gearbox - output shaft assembly should
howewer be provided up to the second engine-drive reduction. Since
the mechanical friction is proportional to the displacement and
less load-sensitive, the efficiency is higher. The engine brake
may be kept whilst increasing the power of the engine, supported
by a speed limiter on the vehicle.
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