In-situ torque measurements in hybrid electric vehicle powertrains

For several years, ANL has taken a leading role in the benchmarking of various advanced hybrid vehicles for the US FreedomCAR industry-government partnership. Early designs provided highly desirable direct engine torque measurement (with telemetry for non-contact signal acquisition) for steady-state and transient operation in an operating Prius powertrain. Newer designs have done away with a sizable spacer and left the powertrain configuration intact. This was made possible by creating a new flywheel damper unit that incorporates the torque sensor, thus the powertrain fits back together without body modifications. Tradeoffs such as signal dynamic range and filtering are challenges that have been addressed by newer generation designs. Close proximity to the stator coils in the Accord HEV prompted the use of a digital telemetry for noise immunity. In all, there are seven (7) unique designs that have been specified and built through the sensor vendor and installed in advanced hybrid electric vehicles. Along with the axle torque measurements and other measurements the power flows of the powertrain system can be tracked for nearly every component from the engine to the chassis dynamometer. This data is key to benchmarking in great detail the potential of advanced technology for use in passenger cars.