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A method is described for predicting the reliability and useful life of an automotive powertrain system using a warranty database or from warranty records. The database requires failure corrections for misdiagnosis from duplicate data, trouble-not-identified records and multiple failure modes. Compensations not included in the database for high-mileage drop-out and warranty repairs less than the deductible amount, are also necessary. As an example, the cumulative hazard function of the Bathtub Hazard Rate distribution is fitted to the converted removal data of a typical automotive powertrain, to determine the product life characteristics. An algorithm written in Basic language is used to obtain the analytical results.

NVH requirements are critical in new driveline developments. Failure modes due to resonances must be carefully analyzed and potential root causes must have adequate countermeasures. One of the most common root causes is the modal alignment. This work shows the steps to design and optimize a new plastic bracket for an automotive half shaft bearing. This bracket replaces a very stiff bracket, made of cast iron. The initial design of plastic bracket was not stiff enough to bring natural frequency of the system above engine second order excitation at maximum speed. The complete power pack was modeled and NVH CAE analysis was performed. The CAE outputs included Driving Point Response, Frequency Response Function and Modal analysis. The boundary conditions were discussed deep in detail to make sure the models represented actual system.

Diesel NOx emissions control utilizing combined Lean NOx Trap (LNT) and so-called passive or in-situ Selective Catalytic Reduction (SCR) catalyst technologies (i.e. with reductant species generated by the LNT) has been the subject of several previous papers from our laboratory [ 1 - 2 ]. The present study focuses on hydrocarbon (HC) emissions control via the same LNT+SCR catalyst technology under FTP driving conditions. HC emissions control can be as challenging as NOx control under both current and future federal and California/Green State emission standards. However, as with NOx control, the combined LNT+SCR approach offers advantages for HC emission control over LNT-only aftertreatment. The incremental conversion obtained with the SCR catalyst is shown, both on the basis of vehicle and laboratory tests, to result primarily from HC adsorbed on the SCR catalyst during rich LNT purges that reacts during subsequent lean engine operation.

Urea-selective catalytic reduction (SCR) after-treatment systems are used for reducing oxides of nitrogen (NOx) emissions in medium and heavy duty diesel vehicles. This paper addresses control-oriented modeling, starting from first-principles, of SCR after-treatment systems. Appropriate simplifications are made to yield governing equations of the Urea-SCR. The resulting nonlinear partial differential equations (PDEs) are discretized and linearized to yield a family of linear finite-dimensional state-space models of the SCR at different operating points. It is further shown that this family of models can be reduced to three operating regions. Within each region, parametric dependencies of the system on physical mechanisms are derived. Further model reduction is shown to be possible in each of the three regions resulting in a second-order linear model with sufficient accuracy.