ELBOW-EXHAUST 2253054 - Caterpillar

Aftertreatment Air System
Illustration 16 g06257978
(1) ARD body
(2) ARD head
(3) Line for the combustion air
(4) Exhaust from turbocharger
(5) Exhaust manifold
(6) Turbocharger
(7) Compressed air to aftercooler
(8) ARD combustion air valve
(9) Combustion air inlet pressure sensor
(10) Exhaust air to DOC and DPFExhaust AirExhaust air flows from the turbine housing to the ARD body. The exhaust air then flows through the Diesel Oxidation Catalyst (DOC) and the DPF. The exhaust air then exits through the SCR.Combustion AirThe air used to supply the ARD head is taken from the turbocharger compressor outlet. The pressure of this air is measured at the inlet to the ARD combustion air valve by the combustion air inlet pressure sensor. The air is then metered by the ARD combustion air valve. The ARD combustion air valve contains a DC motor and analog position sensor. The aftertreatment ECM controls the ARD combustion air valve by sending it a desired opening position. The ARD combustion air valve moves the desired amount and the new valve position is transmitted back to the aftertreatment ECM.
Illustration 17 g06257980
(8) ARD combustion air valve
(11) Electronic Control Module (ECM)
(12) Desired position command
(13) Actual valve position dataOnce the air has been metered by the ARD combustion air valve, the air enters the ARD head. The ARD head contains a swirling plate that is designed to agitate the air that is being mixed with the fuel. This agitated air allows for a precise burn of the air/fuel mixture.Cooling System
Two lines circulate coolant in the ARD head. The coolant is used to extend the life of the O-ring for the ARD nozzle.Diesel Particulate Filter (DPF) System
Illustration 18 g06257983
(1) DPF inlet and delta pressure sensors
(2) DPF inlet temperature sensorThe DPF system contains two types of filter media. The first filter media that exhaust gas is exposed to is the Diesel Oxidation Catalyst (DOC). This filter is a flow through style filter. The DOC is contained in the inlet section of the DPF cannister. The DOC filter contains platinum and palladium. The minerals aid in oxidizing hydrocarbons, carbon monoxide, and soluble organic fractions as the exhaust gas flows through the filter. The inlet section of the DPF cannister contains a temperature sensor, a pressure tap for the DPF inlet pressure sensor, and a DPF delta pressure sensor. All three of these components are before the DOC. The purposes of these components are:DPF inlet temperature sensorThe DPF inlet temperature sensor measures the temperature entering the DPF cannister assembly. This temperature is used to control the ARD fuel and ARD air flow to maintain a desired DPF inlet temperature during regeneration.DPF Delta Pressure sensorThe delta pressure sensor is also used to measure soot collected in the DPF. The delta pressure sensor is measuring the pressure drop across the DPF. Since the delta pressure sensor is measuring flow resistance across the DPF, the sensor will also detect ash loading.DPF Inlet Pressure sensorUsed to measure the backpressure being generated by the DPF.Once the exhaust gas flows through the DOC, the exhaust gas enters the DPF. The DPF is