Strategies for Achieving pre DPF Regeneration Temperatures using in Cylinder Post Injection on a Common Rail Diesel Engine with EGR, DOC and Intake Throttle 2010-36-0306

A DPF (Diesel Particulate Filter) is a device designed to remove diesel particulate matter or soot from the exhaust gas of a diesel engine. Wall-flow diesel particulate filters usually remove 85% or more of the soot. In addition to collecting the particulate, a method must exist to clean the filter. Wall-flow filters are designed to burn off the accumulated particulate at regular intervals, and this can be achieved through engine modifications such as in-cylinder post injections, throttling of the intake air, and using the EGR valve during overrun all to achieve 630degC at the DPF. Running the regeneration cycle too often, while keeping the back pressure in the exhaust system low will use extra fuel, with increased oil dilution, which will increases the chances of diesel engine runaway and engine damage. Regenerating infrequently runs the risk of blocking the DPF and also causing engine damage and/or uncontrolled regeneration and possible DPF failure. Quality regeneration control software is a necessity for longevity of the active DPF system and control of the different techniques. The overall system needs to be robust and function regardless of environmental conditions, driver style, drive cycle, ambient conditions such as altitude and also engine component tolerances such as fuel injector delivery, all in all a challenging task.

This paper will discuss the details of some of the calibration techniques for achieving all of the targets. This is based on experience gained from calibrating for production a 2.0-liter 4cyl diesel engine using common rail injection, EGR, DOC catalyst, VNT, intake air throttling, T4 temperature sensor, Pre cDPF temperature sensor and Delta-P sensor across the DPF. With the DPF being packaged some 60 cm from Catalyst out. The schematic of the system is shown.