Powertrain Calibration Techniques

Ernst Winklhofer; Alois Hirsch; Harald Philipp; Michael Trifterer; Manuel Berglez

doi:10.4271/2019-24-0196

Meeting the particle number (PN) emissions limits in vehicle test sequences needs specific attention on each power variation event occurring in the internal combustion engine (ICE).

ICE power variations arise from engine start onwards along the entire test drive. In hybrid systems, there is one further source for transient ICE response: each power shift between E-motor and ICE introduces gas flow variations with subsequent temperature response in the ICE and in the engine aftertreatment system (EAS). This bears consequences for engine out emissions as well as for the EAS efficiency and even for the durability of a catalytic converter.

As system calibration engineers must decide on numerous actuator parameters, their decisions, finally, are crucial for meeting legislative limits under the boundary conditions given by the hybrid vehicle’s drive environment.

The paper reports on a methodology to measure and evaluate the ICE and EAS response to the vehicle drive requirements and the power shift dynamics between E-motor and ICE.

Focus in particular is given to

1
particle emissions peaks at each engine start and torque variation with measurement of in-cylinder soot formation events and their impact on tailpipe PN emissions.
2
the response of catalyst temperatures to each cylinder’s exhaust gas pulses with an evaluation of temperature and thermoshock risks.

Both topics are related to the ICE’s individual combustion cycles’ mixture formation and gasflow characteristics. Consequently, in-cylinder soot formation, catalyst temperature, tailpipe PN flow are recorded together with the power output of E-motor and ICE.

Such data allow system development and calibration to benefit from direct insight into ICE events, as any parameter variation’s effect is instantly recognized in the measurement system’s evaluation procedures.

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Powertrain Calibration Techniques 2019-24-0196

SAE MOBILUS