As part of the U.S. Environmental Protection Agency’s (EPA’s) continuing assessment of advanced light-duty automotive technologies in support of regulatory and compliance programs, a 2018 Toyota Camry front wheel drive eight-speed automatic transmission was benchmarked. The benchmarking data were used as inputs to EPA’s Advanced Light-duty Powertrain and Hybrid Analysis (ALPHA) vehicle simulation model to estimate GHG emissions from light-duty vehicles.
ALPHA requires both detailed engine fuel consumption maps and transmission torque loss maps. EPA’s National Vehicle and Fuels Emissions Laboratory has developed a streamlined, cost-effective in-house method of transmission testing, capable of gathering a dataset sufficient to characterize transmissions within ALPHA. This testing methodology targets the range of transmission operation observed during vehicle testing over EPA’s city and highway drive cycles.
With this method, the transmission is tested as a complete system, as opposed to disassembling the transmission components and testing each separately. This paper describes the benchmarking process used to gather transmission data and the test results obtained. A UB80E eight-speed automatic transmission from a 2018 Toyota Camry was installed in an engine dynamometer test cell along with a 4-cylinder 2.5L A25A-FKS engine from the same vehicle. The test dataset collected from the transmission includes gear efficiencies, torque converter slippage and K factors, spin losses, oil temperature and pressure, and CAN bus data.
The transmission data collected with this benchmarking method were used as inputs to the ALPHA full vehicle simulation model. ALPHA simulation results were validated using vehicle chassis dynamometer test data from the 2018 Toyota Camry containing this engine and transmission. The ALPHA simulation also allowed the Toyota UB80E transmission to be compared to other benchmarked transmissions.