Systemic Approach for Piston Ring Designs to Reduce Raw Particle Emissions
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© Tenneco Inc.
Systemic Approach for Piston Ring Designs to Reduce Raw Particle Emissions
Tenneco developed a simulation software that analyzes the influence of particle emissions, displays them using a particle indicator and thus optimizes the design of piston ring packs. Using this systemic development approach, it has, for example, been possible to reduce raw particle emissions by up to 39 % in WLTC and RDE driving cycles.
OPTIMIZING GAS, FUEL, AND LUBRICANT FLOWS
The current legislation concerning exhaust and particle emissions is pre senting powertrain developers with major challenges. Despite the use of particle fil ters to help reduce particle emissions, the increasingly strict legal requirements often lead to the permitted respective thresh olds being exceeded in operating scenar ios such as cold starts or sudden and sig nificant load variations in hybrid applica tions. Therefore, more efficient processes are needed [1, 2].
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In addition to directly influencing particle formation by improving the combustion process, engine developers have recognized the importance of optimizing the secondary effects of gas, fuel, and lubricant flows under the loads in the engine cycle. The design of the piston/piston ring/cylin der system is one of the key challenges involved in reducing raw particle emis sions. Against this backdrop, Tenneco Powertrain has developed a systemic approach for improving the design of these components in order to lower the levels of raw particle emissions.
The new approach has been validated by means of engine tests. INFLUENCE OF THE PISTON RING ASSEMBLY
The mechanisms that influence the parti cle number are shown in FIGURE 1. In order to be able to evaluate the effect of these mechanisms, they must be assessed according to time and characteristics during an engine cycle for the operating points under consideration. Depending on the crank angle, either the particle for mation process or the oxidation process will be predominantly influenced. The characteristic of the mechanism deter mines whether the potential impact on the particle number is minimal or pro nounced. The particle creation processes, such as nucleation and oxidation, are influenced by the fluids with a hydrocar bon content that are available in large quantities in the piston/piston ring/cylin
AUTHORS
Thomas Bastuck, M. Sc. is Project Manager Pre-Development at Tenneco’s Powertrain business unit in Burscheid (Germany).
Florian Böhnke, M. Eng. is Project Engineer Pre-Development at Tenneco’s Powertrain business unit in Burscheid (Germany).
der system. The transport of the fluids is affected by relative movements between the piston and the rings, wear, poor lubri cation, pressure between the rings, cylin der distortion, and piston ring conforma bility. Due to the complexity of the inter actions between the components under operating conditions, the influences on the physical parameters within the piston ring assembly need to be investigated from an analytical perspective. Simulation is an ideal means o
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