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| Illustration 1 | g02162626 |
Typical example (1) Diesel Oxidation Catalyst (DOC) (2) Securing clamp (3) Torca clamp (4) Diesel Particulate Filter (DPF) (5) Securing clamp (6) Torca clamp (7) Lifting eye (8) Air inlet for Aftertreatment Regeneration Device (ARD) (9) Connections for coolant manifold (10) Lifting eye | |
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| Illustration 2 | g02162641 |
Typical example (11) Outlet to exhaust system (12) Aftertreatment Regeneration Device (ARD) (13) Lifting eye (14) Exhaust Inlet (15) Mounting cradle | |
The Engine Aftertreatment System for the engine consists of the following components.
- Aftertreatment Regeneration Device (ARD)
- Diesel Oxidation Catalyst (DOC)
- Diesel Particulate Filter (DPF)
The Diesel Oxidation Catalyst (DOC) oxidizes the carbon monoxide and the hydrocarbons that are not burnt in the exhaust gas into carbon dioxide and water. This is a through flow device that will continue to operate during all normal engine operating conditions.
The Diesel Particulate Filter (DPF) collects all solid particulate matter in the exhaust gas.
The Aftertreatment Regeneration Device (ARD) increases the exhaust gas temperature to a sufficient level. The soot that is collected in the DPF is oxidized to carbon dioxide.
A flexible exhaust pipe connects the engine to the Clean Emissions Module (CEM). Refer to Disassembly and Assembly for the correct procedure to install the flexible exhaust pipe.
The solid particulate matter that is collected by the DPF consists of soot (carbon) from incomplete combustion of the fuel and inorganic ash from the combustion of any oil in the cylinder.
The rate of accumulation of ash is slow. The filter is designed to contain all the ash that is produced until the defined service interval.
The soot that is collected must be removed at regular intervals. Removal of the soot is achieved by elevating the exhaust gas temperature by burning fuel in the ARD for a short time period. If the exhaust gas temperature is high enough, the ARD oxidizes the soot into carbon dioxide, which then passes through the filter and into the atmosphere. The ARD may automatically switch ON and OFF. The ARD may be manually controlled by the operator. The ARD is controlled by the sensor for the soot level. The sensor for the level of soot will ensure that the level of soot in the filter is kept within limits. This is referred to as a regeneration of the filter.
In order to regenerate the DPF at the right time, the engine ECM must know how much soot is in the DPF. Measurement of soot is accomplished through the following means:
- Delta pressure measurement across the DPF
- Radio frequency measurement across the DPF
- Calculated model based on developed engine out soot measurements
The information gathered from these three inputs is then converted into a percentage of soot output that is viewable through electronic soot level gauges. These gauges can be found in the cab of most applications as well as various operator displays that are used with most engines. The soot level may be displayed as a graphical bar, or as an actual percentage. Soot level can also be viewed through the electronic service tool.
The frequency of regeneration will depend on the operating conditions of the engine. The frequency of regeneration will depend on the ambient conditions of the operation of the engine. Regeneration will be most frequent if the application operates with a high transient content or the atmospheric temperature or the altitude is high.
Soot Level Outputs
The soot level percentage that is generated by the engine ECM is used in determining:
- When to activate the DPF lamp
- When to activate the action lamp (for high soot load events)
- When to activate the action alarm (for high soot load events) (if equipped)
- When to activate the forced engine low idle strategy
- When to activate the forced engine shutdown strategy
- Operator initiated regeneration lockout
- When a force switch regeneration is allowed
- When a low speed regeneration is allowed
- When a high speed regeneration is allowed
DPF Lamp - The DPF lamp will be illuminated at a 90 percent soot level on engines.
Action Lamp - The action lamp will be illuminated at a 100 percent soot level for engines. The DPF lamp will remain on with the action lamp.
Action Alarm - The action alarm will be activated at a 116 percent soot level for engines.
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 regeneration.
Regeneration lockout - Regeneration will be locked out from the operator once the soot level percent has been at 116 percent for 10 minutes. Regeneration can only be performed by using the "Manual DPF Regeneration" service procedure within the electronic service tool.
Forced engine shutdown strategy - The forced engine shutdown strategy will be activated when the soot level reaches 140 percent soot level. The engine will initially idle for 30 seconds before completely shutting down. The DPF can no longer be regenerated and must be replaced.
Force Switch Regeneration - Regeneration initiated by the force switch is allowed once soot level is greater than 15 percent.
Low Speed Regeneration - Low speed regeneration will be allowed once soot level is greater than 30 percent.
High Speed Regeneration - High speed regeneration will be allowed once soot level is greater than 60 percent.
Regeneration Types and Operating Criteria
Automatic Regenerations
There are two types of automatic regeneration. These regenerations are referred to as low speed regeneration and high speed regeneration. Low speed regeneration and high speed regeneration must meet certain criteria before the regeneration will automatically activate. This criteria is outlined below. Both low speed regeneration and high speed regeneration can be configured through the electronic service tool.
Low Speed Regeneration
Low speed regeneration occurs when the application is in a stationary or non-working condition. Low speed regenerations allow for the most precise control of fuel and airflow. Low speed regenerations require the least amount of fuel to be used as well as having the lowest duration times. The parameters listed below must be met to activate the low speed regeneration.
Engine Speed - Engine speed must be within the low idle speed setting and 1500 rpm. If engine speed exits this window for 1 second, the regeneration will terminate.
Fuel Delivery - Delivered fuel volume must be within 10 and 80 cubic millimeters of fuel. If fuel delivery exits this window for 1 to 2 seconds, the regeneration will terminate.
Readiness indicators - The ECM will monitor a number of different parameters that are communicated through the CAN datalink from other ECMs on the machine (if equipped). These parameters are referred to as regeneration readiness indicators. Examples of these parameters are: parking brake on or off, hydraulic lock on or off, vehicle speed, throttle position and operator seat switch. These parameters are used in determining the best opportunity to perform a low speed regeneration. As the ECM processes the data from these inputs, the ECM is able to predict when the machine will likely be in a non-working condition. During this non-working condition the ECM will attempt to perform a significant amount of regeneration. The regen readiness parameters are not viewable in the electronic service tool.
Engine Speed Control During Low Speed Regeneration - If the engine speed is below 975 rpm when a regeneration is activated, the ECM will elevate engine speed between 1000 and 1400 rpm. This change depends on the application. This change in speed allows for the proper amount of air flow required to maintain an optimal DPF inlet temperature for regeneration. The elevated engine speed may remain for up to 1 minute after a regeneration has stopped.
High Speed Regeneration
High speed regeneration typically occurs when the engine is in normal operating mode. High speed regenerations consume more fuel and take a longer time to complete compared to low speed regenerations. This longer time is due to maintaining lower desired DPF inlet temperatures to avoid damaging the DPF from extreme changes in temperature. High speed regeneration has two distinct operating regions. These operating regions are determined by the soot level. The first region is between 60 and 75 percent soot level, the second region is between 75 and 90 percent soot level. The 60 to 75 percent region has a tighter engine operating mode in which high speed regeneration can occur. The 75 to 90 percent region opens the engine operating mode to allow for the highest opportunity to perform a high speed regeneration. The parameters listed below outline the operating criteria that are monitored to activate and sustain high speed regeneration.
Note: All of the parameters listed below are independently developed for each application. All applications may not meet the exact criteria outlined below.
Engine speed (60-75% soot level) - Engine speed is typically between 1350 and 2200 rpm. Engine speed should not change more than 200 rpm per second.
Engine speed (75-90% soot level) - Engine speed is typically between 975 and 2350 rpm. Engine speed should not change more than 400 rpm per second.
Fuel Delivery (60-75% soot level) - Fuel delivery is typically within 30 cubic millimeters of the upper limit defined by the engine power rating. As the engine speed increases the window for allowed fuel delivery increases.
Fuel Delivery (75-90% soot level) - Fuel delivery is typically within 10 cubic millimeters and the upper limit defined by the engine power rating. In this soot level range, the upper fuel limit is the maximum allowed fuel at each rpm.
Combustion Air Inlet Pressure (60-75% soot level) - The combustion air inlet pressure should not change more than 65 kPa (9.4 psi) per second.
Combustion Air Inlet Pressure (75-90% soot level) - The combustion air inlet pressure should not change more than 80 kPa (11.6 psi) per second.
Engine Speed Control during High Speed Regeneration
Most aspects of high speed regeneration are transparent. If the engine is in normal working mode and the throttle is released, the low idle will be limited to 1000 rpm. Limiting the engine speed to 1000 rpm will maintain the regeneration. If the engine speed must be brought to the programmed low idle speed, pressing the disable regen switch will stop the regeneration. The engine will return engine speed to the programmed low idle speed.
Manual Regenerations
Manual regeneration is accomplished by pressing the force regeneration switch. Refer to the Operation and Maintenance Manual for correct location of switch. For some applications, the engine must be operating in the low speed regeneration region outlined above. Also soot level must be greater than the amount listed for forced switch regeneration in the soot level outputs section listed above.
Fuel System for the Clean Emissions Module
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| Illustration 3 | g02301233 |
Typical example (A) Fuel from primary fuel filter (1) Fuel pump for the ARD (2) Fuel control manifold (ARD) (3) Fuel pressure sensor (4) ARD head (5) Fuel line (B) Fuel return to secondary fuel filter | |
Fuel flows from the primary fuel filter/water separator to the ARD fuel pump (1). The ARD fuel pump (1) provides fuel for ARD head (4) .
Fuel pressure sensor (3) send a signal to the ECM. The signal indicates the fuel pressure inside the fuel control manifold (ARD) (2). The fuel is sent directly to the ARD head (4) from the fuel control manifold (ARD) (2) .
Excess fuel from the fuel pump for the ARD (1) is then returned to the secondary fuel filter.
Air System for the Clean Emissions Module
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| Illustration 4 | g02303496 |
Typical example (1) ARD body (2) ARD head (3) Line for the combustion air (4) Exhaust from turbocharger (5) Low-pressure turbocharger (6) Exhaust manifold (7) High-pressure turbocharger (8) ARD combustion air valve (A) Exhaust air to DOC and DPF (B) Compressed air to aftercooler | |
Exhaust Air
Exhaust air flows from the turbine housing to the ARD body. The exhaust air then flows through the Diesel Oxidation Catalyst (DOC) and the DPF.
Combustion Air
Pressurized air from the turbocharger flows to the combustion air valve. The combustion air valve controls the amount of air that is supplied to the ARD Head. The combustion air is used with the supplied fuel and the spark plug to create the flame.
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.
Electronic Controls
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| Illustration 5 | g02304673 |
Typical example (1) Soot Sensors (2) Combustion air inlet pressure sensor (3) DPF differential pressure sensor (4) DPF inlet pressure sensor (5) DPF inlet temperature sensor (6) Fuel pressure sensor | |
All electronic devices on the CEM are controlled by the engine ECM. The ECM sends signals in order to complete the following functions: sending fuel pressure to the ARD head, the ignition and the actuation of the heated nozzle.
Sensors
Absolute Pressure Sensor ( combustion air valve) - This sensor determines the pressure of the combustion air in the combustion air valve.
Absolute Pressure Sensor ( Exhaust Gas) - This sensor measures the pressure of the exhaust gases as they enter the DOC.
Inlet Temperature Sensor - This sensor determines the temperature of the air that is entering the DOC and the DPF.
Soot Sensors - The Soot Sensors use a radio frequency to determine the amount of soot in the DPF. The Soot Sensors use a coaxial cable in order to send a signal to a control box that is mounted on the machine. The control box conditions the signal. Then, the control box sends a value to the engine ECM, which converts the value to a soot level.
Fuel Pressure Sensor - The sensor determines the pressure of the fuel that is being supplied to the ARD Head.
Flame Detection Temperature Sensor - This sensor determines if a flame is present.
Heated Nozzle
The orifice for the fuel creates a high amount of atomization of the fuel for ignition and operation.
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| Illustration 6 | g02304633 |
Typical example (1) Coolant inlet (2) Coolant outlet (3) Heated Nozzle (4) Flame detection temperature sensor (5) Fuel fitting | |
The heating element in the nozzle periodically cleans the nozzle when the ECM sends a command. The interval of the cleaning is determined by the hours of operation on the engine.
Ignition System for the Clean Emissions Module
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| Illustration 7 | g02304634 |
Typical example (1) Ground point on the ARD combustion head (2) ARD head (3) Ignition wire | |
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| Illustration 8 | g02303173 |
Typical example (4) Spark plug (5) Ground probe (6) Spark plug electrode | |
The ARD ignition system has two circuits. The primary circuit is between the ECM and the ignition coil. The secondary circuit is between the ignition coil and the ARD combustion head. The current flow through the primary circuit indicates the condition of the primary circuit and of the secondary circuit. The ECM monitors the current flow through the primary circuit. In this way, the ECM is able to detect problems with the primary circuit and the secondary circuit.
The ECM creates an ignition pulse 40 times each second whenever the engine speed is greater than 500 rpm. Wiring sends the signal to the primary side of the ignition coil. The ignition coil is located on the panel for the electronics on the Clean Emissions Module (CEM).
The ignition coil converts the ignition pulse into a high voltage signal. Ignition wire connects the ignition coil output to the spark plug. The spark plug is threaded into the ARD combustion head. The spark jumps between the spark plug electrode and ground probe inside the ARD combustion head. The spark ignites the air/fuel mixture.
The ground wire ensures that the secondary ignition circuit is complete between the ARD combustion head and the ignition coil. The ground wire runs inside the insulation that is wrapped around ignition wire. The ground wire is connected to two ground points. One ground point is on the ARD combustion head. One ground point is on the panel for the electronics near the ignition transformer.