Measuring and modeling parasitic losses in driveline components continues to be an important topic in product development. There are existing standards (SAE J2985 [1], J3039[2], and J3218[3]) for measuring and reporting spin loss parasitic losses. All these tests are conducted at fixed temperatures of 28°C and 65°C with a variety of controls and measurement positions to ensure these conditions. The limitation of these methods is that they do not represent the actual vehicle range of operating temperatures. In 2020, Guarino et al presented the paper SAE 2020-01-1413 [4] on development of a test method for beam axles (which was developed into SAE J3218). In the paper, a floating temperature sweep test method was developed for testing efficiency over a range of temperature at a fixed operating condition.
This paper will highlight adapting the efficiency floating temperature sweep test method and applying it to spin loss measurement (a transfer case was used in this development). To extend value to the measurements, the measurements were combined to create a surface map to be used in vehicle modeling. The development of the process to create the surface map will be reviewed and applied in a sensitivity of the system to different factors (such as, temperature and speed). The result is a spin loss speed-temperature-torque surface map / equation and a proposed test method that is faster with reduced complexity of setup.
