Kubota D1803-CR-E4 - Control of EGR System; EGR Cooler; EGR Valve; Function of EGR Cooler

5.4 Control of EGR system
<System control diagram> / System schematics
(1) EGR valve
(2) Engine ECU
(3)
Coolant temperature sensor
(4) Air flow sensor
(5) Others
(A) Opening instruction
(B) Valve position sensor value
The engine ECU (2) controls the amount the EGR
valve (1)
is open based on the coolant temperature
sensor (3) and air flow sensor (4) etc. values.
The EGR valve (1) is wide open at coolant
temperatures lower than 65 ℃ (149 ℉) and starts to
close at coolant temperatures of 65 ℃ (149 ℉)and
higher.
When a DTC is occurred, one system action is to force
closure of the EGR valve (1).
5.5 EGR cooler
5.5.1 Outline of EGR cooler
The EGR cooler cools the exhaust gas.
This suppresses
generation of nitrogen oxides (NOx)
by reducing combustion temperature.
5.5.2 Structure of EGR cooler
The EGR cooler is made up of the cooler and tubes.
(1) EGR cooler
(A) Exhaust gas inlet
(B)
Exhaust gas outlet
(a) Coolant inlet
(b) Coolant outlet
5.5.3 Function of EGR cooler
The EGR cooler cools the exhaust gas.
Exhaust gas
passes through narrow tubes provided in
the cooler and cools the area around these with engine
coolant to lower the temperature of the exhaust gas.
This enables preventing rise in intake air temperature.
As a result, this suppresses generation of nitrogen
oxides by reducing combustion temperature.
5.5.4 Specification of EGR cooler
Cooling method Water cooled
Cooling perform-
ance
Exhaust gas inlet
temperature
600 ℃
11
12 ℉
Exhaust gas outlet
temperature
Approx.
278 to 310 ℃
533 to 590 ℉
NOTE
• Exhaust gas
outlet temperature is depended on
gas flow rate.
5.6 EGR valve
5.6.1 Outline of EGR valve
The EGR valve regulates recirculation gas volume.
MECHANISM
5. Exhaust gas recirculation (EGR) system 4. ENGINE
D1803-CR-E4,D1803-CR-TE4,D1803-CR-TIE4,V2403-CR-E4,V2403-CR-TE4,V2403-CR-TE4BG,V2403-CR-TIE4
4-47
KiSC issued 12, 2018 A