Control Of Diesel Particulate Filter (Dpf) System - wsm 03-CR-E4 Workshop Manual

4. ENGINE

9.4 Control of diesel particulate filter (DPF) system

The engine ECU determines the PM accumulation status from information from each sensor and sets regeneration or
cleaning level and timing.
1. Automatic active regeneration
When the PM level reaches 1, the engine ECU performs regeneration control to burn the PM that has been
accumulated.
If the DOC temperature (value of exhaust gas temperature sensor T
gives instruction to the injector to perform post injection.
Unburned fuel is combusted in the DOC raising the exhaust gas temperature to 550 ℃ (1022 ℉) or higher and
combusting the PM in the DPF.
If the DOC temperature is less than 250 ℃ (482 ℉), the fuel will not burn even if a post injection is performed so
post injection is not performed.
Therefore, regeneration is also not performed.
If the DOC temperature is 550 ℃ (1022 ℉) or higher, the PM combusts on its own so post injection is not
performed (Passive regeneration state).
In addition, if auto regeneration is not completed within specified time while in PM level 2 state, the engine ECU
requests parked regeneration.
2. Parked active regeneration
When the PM level reaches 3, the engine ECU sends a warning to the machine on which it is equipped to perform
parked regeneration and commands output restriction.
During parked regeneration, pre-programmed operation processes are performed automatically.
As a preparation step for regeneration, first the intake throttle valve is operated reducing the amount of intake air
raising the exhaust gas temperature.
Further, engine speed is raised and adjusted so that the DOC temperature rises to 250 ℃ (482 ℉) or higher.
After the DOC reaches 250 ℃ (482 ℉) or higher, control is performed the same as for auto regeneration.
When regeneration is finished, the operation state is returned what it was prior to auto regeneration (idle speed).
3. Forced regeneration
When the PM level reaches 4, forced regeneration has to be performed using a failure diagnostics tool
(Diagmaster).
Regeneration control itself is the same as that for parked regeneration.
PM warning level
Automatic active
regeneration
0 Not necessary
Automatic active
1
regeneration
4-76
Regeneration method
Parked active re-
generation
× ×
○ ×
) is 250 ℃ (482 ℉) or higher, the engine ECU
0
Regeneration
Regeneration status
with service
tools
○ Not necessary regeneration.
When the warning level
○ reaches 1, regeneration is
started automatically.
MECHANISM
9. Aftertreatment system
Control
－
1. If the DOC temperature
(value of exhaust gas
temperature sensor T )
0
is 250 ℃ (482 ℉) or
higher, the engine ECU
gives instruction to the
injector to perform post
injection.
2. Unburned fuel is com-
busted in the DOC rais-
ing the exhaust gas
temperature to 550 ℃
(1022 ℉) or higher and
combusting the PM in
the DPF.
3. If the DOC temperature
is less than 250 ℃
(482 ℉), the fuel will not
burn even if a post in-
jection is performed so
post injection is not per-
formed. Therefore, re-
generation is also not
performed.
(Continued)
03-CR-E4,03-CR-TE4BG
KiSC issued 02, 2021 A