Английский язык. Писарева Л.П. - 17 стр.

                                   Вариант V
                                       Text
           Port Scavenging of the Single-Cylinder Experimental Engine

    As early as 1911, a single-cylinder experimental engine with a bore of 1000 mm
was put on the testbed. The piston stroke was 1100 mm, speed 150 rev/min, and
cylinder rating about 2000 hp. The breathing process in this engine is controlled by the
piston, thus inlet and exhaust valves in the cylinder head are not necessary. During
downward travel the piston uncovers the exhaust ports in the vicinity of bottom dead
centre. After expansion of the gases in the cylinder, the residual gases expand in the
exhaust pipe. During further downward travel the piston also exposes the scavenging
ports lower down; the combination air present in the scavenging air receiver under
slight pressure enters the cylinder and scavenges it. Location and arrangement of the
ports determine the direction of air flow and hence the effectiveness of scavenging. So
as to have as much combustion air as possible in the cylinder at the beginning of
compression, additional charge of air is simultaneously supplied. A second row of
scavenging ports projecting above the exhaust ports is closed by mechanically actuated
valves while the piston is moving downwards, but during scavenging these additional
scavenging ports are opened and permit- after the downward-moving piston has again
covered the exhaust ports-the cylinder to be additionally charged to the pressure of the
scavenging air. Some little time later, the mechanically actuated valves for additional
charging were replaced by automatic non-return valves. Introduction of port scavenging
brought about considerable simplification. The gas valves in the cylinder head
eliminated, as was the mechanism for actuating them. Although the arrangement of the
exhaust and scavenging ports has been changed in the course of time, the scavenging
process introduced than has in principle been retained successfully up to the present
day.



                                      Vocabulary

port                           окно
scavenging                     продувка
bore                           диаметр (внутренний) втулки цилиндра
piston stroke                  ход поршня
rating                         мощность
inlet (exhaust) valve          впускной (выпускной) клапан
cylinder head                  крышка цилиндра
downward                       вниз
uncover=open                   вниз
bottom dead centre             Н.М.Т.
expansion                      расширение
residual                       остаточный
location                       расположение
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