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required. At idle and low loads, a mixture of α = 0.7 ... 0.8 is
required.
In medium load mode it is advisable to work on the
economically impoverished mixture (α = 1,1 ... 1,15). The work of
the engine in the mode of maximum power is possible only on the
enriched mixture with α = 0,8 ... 0,9, at which the combustion rate
is greatest. Compulsory enrichment of the mixture is required
under intensive acceleration.
The work of the system can be divided into five main modes:
start, idling, mode of average loads, the mode of maximum loads
and the regime of sudden opening of the throttle (intensive
overclocking). Maintenance of the engine in these modes is carried
out with the help of special devices: a launcher, idling systems, the
main dispensing system, the economizer, the accelerating pump. In
addition to the listed devices, the engines of trucks are equipped
with limiters for maximum engine speed.
When studying the power system you need to get acquainted
with the listed devices, to deal with their work, by fuel, air and
combustible mixture.
Fueling in the diesel engine takes place in two stages: first, the
fuel-pump pump fuel through the filters to the Top Dead Centre
(TDC), and after the NVT provides fuel to the injectors - in the
engine cylinders. To the peculiarities of the working process of
diesel engines, the combustion of the combustion mixture from the
high air temperature (t = 500 ... 600 ° C) which is heated with
compression, should be considered first. For this purpose, diesel
engines have a high degree of compression. For fast and complete
combustion of fuel it is necessary to ensure its good warming and
mixing with air. This is achieved by means of rather fine fuel
spraying or by directing the fuel trick to the hottest part of the
combustion chamber, the use of special forms of combustion
chambers.
The ignition delay of diesel fuel from the moment of its
injection into a cylinder depends on the design of the engine and
its thermal regime, as well as on the chemical stability of fuel. In
the latter case, the quality of diesel fuel is estimated by the cetane
number. A characteristic feature of diesel engines is that the
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