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EMISSION CONTROL SYSTEMS -
O F F - - -
m
60 msec. 60 msec.
EGR CONTROL VALVE
Spring
The EGR control valve is a diaphragm that functions
to control the flow of EGR gases by opening and
closing the valve according to the negative pressure
(vacuum) acting upon the partitioned chamber.
NOTE
Duty ratio
The duty ratio is the ON duration ratio of 16.7 Hz pulse or T2/T1.
The higher the duty ratio, the more mean current flows to the
boost meter. and as a result, the boost meter reads the higher
value.
The smaller is the duty ratio, the boost meter reads the smaller
value.
iragm
The therm0 valve functions in response to the temperature of
the engine coolant. thus controlling the negative pressure
acting upon the EGR control valve.
The valve opens at a temperature of 65°C (149°F) or lower, and
closes at 65°C (149°F) or higher.
Valve
Exh aust Car Recirculation (EGR) System
To Intake
manifold
Exhaust gas
NOTE
When the negative pressure becomes stronger than
the spring force, the valve opens, as shown in the
illustration, and the exhaust gases can flow.
Apply vacuum
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