Analysis of the pressure loss increase mechanism by Ash accumulated of coated GPF 2019-01-0981
At accelerating exhaust gas regulations during recent years, not only are CO / HC / NOx getting stricter, but so are PN regulations, as represented by Euro 6 d and China 6. PN reduction by engine combustion technology development also progresses, but considering RDE (real driving emissions), PN reduction by after treatment technology is also indispensable. To reduce PN exhausted from a gasoline engine, it is effective to equip a GPF (gasoline particulate filter) to have a filter structure.
We have so far developed a system to replace the TWC (three-way catalyst) of the rear bed with a GPF in order to mount the GPF without changing the layout of the TWC 2 bed system. We chose a coated GPF with filter function and TWC function. Since the amount of washcoat and the initial pressure loss are in conflicting relation with the coated GPF, we developed a coated GPF that can achieve both low initial pressure loss and high purification performance.
Although GPF can collect PM, Ash derived from the engine oil component accumulates and there is a problem that the pressure loss increases. As pressure loss increases, engine power reduction and GPF movement will occur, so it is necessary to reduce pressure loss from Ash accumulation.
In order to clarify the pressure loss increase mechanism by Ash accumulation, we developed equipment to simply accumulate simulated Ash. Using that equipment, we clarified that the pressure loss increase by Ash accumulation of a coated GPF is divided into the initial / mid / late regions, and that the trend changes with GPF volume. From this mechanism we set the GPF volume, which does not lead to GPF movement even at the maximum Ash amount.
This TWC + coated GPF system was applied to the European mass production model in 2018.