TURBO GP-BASIC 10R8733 - Caterpillar

System Operation
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