|
Depending on the vehicle, the installation location of the exhaust gas recirculation valve
is as follows.
<4B12>
Exhaust gas recirculation valve is installed in EGR valve support.
<6B31-Except vehicles for Russia>
Exhaust gas recirculation valve is installed in thermostat housing.
The exhaust gas recirculation valve controls exhaust gas recirculation flow volume using
the stepper motor method and reduces exhaust gas (NOx) and fuel consumption. The exhaust gas
recirculation valve drives the stepper motor based on the signal from engine-ECU. When stepper
motor rotor turns in clockwise or anti-clockwise direction, the shaft fitted with a rotor and
a screw expands and contracts and the movement of the shaft causes the valve to go up and down.
Thus, exhaust gas recirculation path gap is controlled minutely. The stepper motor turns 15° per
step. The stepper motor turns forward or back only up to the angle dictated by the number of
pulse signals (number of steps) from the engine-ECU. In other words, increase and decrease of
the exhaust gas recirculation flow volume depends on the number of signals (number of steps) from
engine-ECU. Engine-ECU changes current flow to the 4 coils (A, B, C, D) in the stepper motor
in sequence according to the phase pattern in the following chart in order to turn the stepper
motor rotor. Open valve changes phase in order of 0 → 1 → 2 → 3 → 0.
Close valve changes phase in order of 3 → 2 → 1 → 0 → 3.
Phase number
|
Stepper motor coil
|
Coil A
|
Coil B
|
Coil C
|
Coil D
|
0
|
ON
|
OFF
|
OFF
|
ON
|
1
|
ON
|
OFF
|
ON
|
OFF
|
2
|
OFF
|
ON
|
ON
|
OFF
|
3
|
OFF
|
ON
|
OFF
|
ON
|
|
