Durability of pollution control measures for L-category vehicles

As part of proposed revisions to the type approval requirements for L-category vehicles (mopeds, motorcycles, tricycles and quadricycles), TRL was commissioned by the European Commission to define a mileage accumulation methodology that would appropriately test the durability of emission relevant components and systems to ensure that the tailpipe emissions of regulated pollutants remain below the required Euro stage limits over the vehicle’s typical life. An in-depth review of existing international durability mileage accumulation cycles found that none were ideal for L-category vehicles in Europe; a new durability cycle, the SRC-LeCV, was developed because the US EPA AMA durability cycle for cars and cycles was outdated in regards to the technologies it tasked and the SRC durability cycle for cars was found to not fully cater for the characteristics and performance of the entire L-category fleet. Literature study and stakeholder consultations identified key degradation mechanisms of: thermal ageing of the pollution control devices (such as the catalytic converter and lambda sensor) via thermal cycling and deceleration fuel cut-off, poisoning of the pollution control devices, carbon deposits and mechanical wear, shocks and vibrations. These were investigated in a test programme at the EU’s scientific and technical research laboratory, the Joint Research Centre (JRC). Four cost–effective durability cycles which invoked the intended ageing mechanisms were developed and validated using a range of L-category vehicles. The categorisation system was aligned with UN GTR No. 2 (WMTC) and improvements to the instructions were made to simplify the execution of the test.