Page 23 - E BOOK ENGINE MECHANICAL M2

3. TURBOCHARGER

(4) Intercooler
The turbocharger is a device that forces and compress-
es intake air into the cylinders to increase engine output.
Since the compressed air is heated to a high tempera-
ture and the air mass is expanded, its density will be
decreased. This means that even if the air pressure is
doubled, the actual air amount will only increase about
1.6 times as much.

By installing an intercooler between the compressor out-
put and the throttle valve, the compressed air tempera-
Fig. 3-5
ture is lowered as the air passes through, the amount of
air itself can be increased in proportional to the pres-
sure, and the intake air charge efficiency will be im-
proved, making then greater engine output.

Also, lowering the compressed air temperature with the
intercooler can contribute to suppress the occurrence of
the knocking, and improving fuel economy by selecting
optimum ignition timing as much as possible.

Fig. 3-6

3. KNOWLEDGE CHECK
Regarding the following sentences of turbochrger, identify which ones are correct or incorrect, and
make the required correction to the wrong portion of the incorrect sentence.

(1) Turbocharger is a kind of supercharger which utilizes the exhaust emission of the engine to rotate
the turbine wheel, and drive the compressor wheel that is assembled on the opposite end of the ro-
tating shaft.
(2) In order to maintain the exhaust gas pressure higher than specific value, the waste gate valve and
the waste gate actuator are provided which open and close the port of the exhaust passage.

(3) The intercooler is provided in the passage between the turbocharger and the exhaust manifold in
order to reduce the temperature of exhaust emission gas. It contributes to suppress the generation of
Nox.

3 - 3 Pub. No. PTAE1225