813960A 4 Mercury SWITCH ASSEMBLY

Illustration 1 g03320982
Typical example
(1) Aftertreatment Regeneration Device (ARD)
(2) Diesel Oxidation Catalyst (DOC)
(3) Diesel Particulate Filter (DPF) The CEM 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 wall flow 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.If applicable, a flexible exhaust pipe can connect 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. Refer to Operation and Maintenance Manual for more information.The soot that is collected must be removed at regular intervals by a process of regeneration.The wall flow DPF continuously regenerates at modest temperatures, using passive regeneration to continually control soot loading.Active regeneration occurs when the engine does not create enough heat in order to regenerate the DPF.Air is supplied to the ARD through pressurized air from the turbocharger and air pump. Fuel is supplied from the leakoff line to the ARD.Fuel is injected onto a wire gauze by the first injector. The fuel is ignited by the glow plug. The ARD is air cooled.The combustion of the fuel generates heat. Once the temperature recorded by the inlet temperature sensor has reached 300° C (572° F), the second injector will inject fuel into the exhaust gas stream. The fuel from the second injector ignites when the fuel comes into contact with the face of the DOC due to the heat created by first injection event.The DOC 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
Calculated model based on developed engine out soot measurementsThe 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 DPF and flashing warning lamp (for high soot load events)
When to activate the forced engine shutdown strategyDPF Lamp - The DPF lamp will be illuminated at a 80 percent soot level on engines.DPF and Flashing Warning 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.Limited speed strategy - The limited speed strategy will be activated after the soot level has reached 100 percent. At this time, the engine will automatically drop to the programmed speed of 1800 rpm with 50 percent engine load. The only method to unlock the limited speed is to perform a regeneration.Forced engine shutdown strategy - The forced engine shutdown strategy will be activated when the soot level reaches 140 percent soot level. The engine will operate between 800 and 1800 rpm. After 30 seconds, the engine will automatically shut down. The engine can be restarted but will only operate for 30 seconds before shutting down again.Force Switch Regeneration - Regeneration initiated by the force switch is allowed at all times.Passive Regeneration - Passive regeneration is allowed at all times.Active Regeneration - Active regeneration will be allowed once soot level is greater than 60 percent.Regeneration Types and Operating Criteria
Regenerations
There are two types of regeneration. These regenerations are referred to as passive regeneration and active regeneration.Passive RegenerationPassive regeneration occurs when the engine is operating and the exhaust temperatures reach sufficient levels.Active RegenerationActive regeneration occurs when the soot load in the DPF reaches 60 percent. The ARD must be used to create the heat necessary to regenerate the DPF.The ARD may perform an active regeneration while the engine is at any operating condition.Active regenerations consume more fuel and take a shorter time to complete compared to passive regenerations. This longer time is due to maintaining lower desired DPF inlet temperatures to avoid damaging the DPF from extreme changes in temperature.Active regeneration has one distinct operating region. The operating region is determined by the soot level. The region is between 60 and 140 percent soot level. The parameters listed below outline the operating criteria that are monitored to activate and sustain active regeneration.Note: All of the parameters listed below are independently developed for each application. All applications may not meet the exact criteria outlined below.Regeneration switch - The disable regeneration switch is not enabled.Engine Coolant Temperature - The engine coolant temperature should be above 70° C (158° F)Engine Load Factor - The engine load factor should be between 0 percent and