0326900 JOHNSON SCREW, Exhaust housing

Illustration 1 g03390047
(1) Diesel Oxidation Catalyst (DOC)
(2) Selective Catalytic Reduction (SCR) catalyst
(3) Diesel Particulate Filter (DPF)
(4) ARD body
(5) Connection for the coolant
(6) ARD head
(7) Pilot fuel line
(8) Main fuel line
(9) Spark plug
(10) Relay for the Heated Nozzle
(11) Line for combustion air
(12) Exhaust from turbocharger
(13) ARD combustion air valve
(14) Compressed air from turbocharger
(15) Ignition coil
(16) ARD fuel manifold
(17) In-line fuel filter
(18) Electric priming pump
(19) Primary fuel filter
(20) Fuel from tank
(21) Aftertreatment Electronic Control Module (ECM)Clean Emissions Module Basics
The Clean Emissions Module (CEM) contains the Aftertreatment Regeneration Device (ARD), Diesel Particulate Filter (DPF) and Selective Catalytic Reduction (SCR) system. The CEM contains a number of mechanical and electrical components that reduce various exhaust emissions emitted from the engine. The CEM uses its own ECM for aftertreatment controls but must communicate (send and receive) with the engine ECM.The two major functions of the clean emissions module are:
Carbon Monoxide and hydrocarbon emitted from the engine are oxidized through the Diesel Oxidation Catalyst (DOC) and the particulate matter (soot) is trapped in the Diesel Particulate Filter (DPF). The trapped particulate matter is cleaned from the DPF through a catalytic reaction and by heating the filter through a process called Regeneration.
NOx emissions emitted from the engine are reduced through a process called Selective Catalytic Reduction (SCR).Aftertreatment Regeneration Device (ARD)
The ARD is primarily used to regenerate, or clean, soot from the DPF. The ARD is also used to heat and maintain the SCR system. The ARD is made up of fuel, air, and electrical subsystems. Regeneration is a process which uses diesel fuel and boost air from the turbocharger to create a high temperature flame. The heat from that high temperature flame is introduced to the inlet of the DPF.The soot load on most Tier IV Final products is burned passively. This is due to the addition of the SCR. The SCR cleans up NOx, which allows the engine to produce more NOx. The engine now produces less soot since the higher NOx output allows soot to burn off at lower temperatures. For this reason active regeneration may not be required to burn soot. Regenerations will still be desired to maintain the ARD head and SCR system.In order to regenerate the DPF at the right time, the aftertreatment ECM must know what the soot level is and how much time has passed since the last regeneration occurred. This time remaining until a regeneration must be performed is displayed on the dash as "Time To Regen" and has soot and time as an input. The soot input is a function of:
Delta pressure measurement across the DPF
Calculated model based on developed engine out soot measurementsThe information gathered from these two inputs is converted into a percentage of soot output. Soot level can be viewed through Caterpillar Electronic Technician (ET).Note: If the "Time To Regen" is driven by the timer it will count down in real time. If driven by soot, it may count down slightly faster than real time depending on soot rate. About 95 percent of applications will be driven by the timer and not soot. If driven by soot, once the "Time To Regen" reads 0 the soot percent is at least 100 percent. Whenever "Time To Regen" reads 0 a regeneration must be performed.Regeneration Triggers
There are four methods for triggering a regeneration:Soot - The DPF will collect soot produced by the engine. An automatic regeneration will become active to reduce soot level. Details on how soot level is used to trigger regenerations are explained in "Regeneration Action Strategies" section.Start-Up Regeneration - A start-up regeneration is initiated by the ECM after a cold engine start. This regeneration is performed to heat the system to a required temperature for Diesel Exhaust Fluid (DEF) dosing to begin. DEF dosing requirements are explained in Systems Operation, "DEF Dosing Control System" section.SCR Maintenance - A regeneration is performed to maintain the SCR system. This regen is triggered when there is ammonia slip or poor NOx conversion. Details are explained in Systems Operation, "DEF Dosing Control System" sectionARD Maintenance - A regeneration is performed to maintain the ARD system. Fresh fuel must be flowed thru the ARD head in order to allow a heated nozzle cycle. The heated nozzle cycle is used to clean the ARD nozzle. Details on the heated nozzle cycle are explained in the "Aftertreatment Fuel System" section.Regeneration Action Strategies
The soot level percentage and time until a regen is required are generated by the aftertreatment ECM and used in determining:
When to activate the DPF lamp
When to activate the action lamp
When to activate the action alarm (if equipped)
When to activate the forced engine low idle strategy
When to activate the forced engine shutdown strategy
Regeneration lockout
When a manual regeneration is allowed
When an automatic regeneration is allowedDPF Lamp - The DPF lamp will be illuminated when soot level reaches 90 percent or "Time To Regen" is less than 3.2 hours.Action Lamp - The action lamp will be illuminated at 100 percent soot level or "Time To Regen" is 0. The DPF lamp will remain on with the action lamp. A "E3719 (16)" or "E3750 (17)" event code will become active.Action Alarm - The action alarm will be activated at a 116 percent soot level. A "E3719 (0)" event code will become active. When the "Time To Regen" has been 0 for 6.4 hours the action alarm will be activated and the engine will be 100% derated. A "E3750 (18)" event code will become active.Forced low idle strategy - The forced low idle strategy will be activated after the soot level has been at 116 percent for 5 minutes. At this time, the engine will automatically drop to the programmed low idle speed. The only method to unlock the low idle speed is to cycle the key switch or perform a manual regeneration.Regeneration lockout - All forms of regeneration will be locked out from the operator once the soot level percent has been at 116 percent for 10 minutes. A "E3714 (31)" code will become active. The engine will shut down but be