SAE J3039:2020 pdf free

SAE J3039:2020 pdf free.Definition and Measurement of Power Transfer Unit Speed-Dependent Parasitic Loss
In order to conduct the testing outlined in Section 4, a suitable temperature-controlled chamber must be used. The chamber should be capable of controlling the PTU temperature without directly conditioning the oil inside (i.e., via convection). The chamber should be capable of achieving an average skin temperature (AST) in the range of-7 to +65 °C (20 to 150°F).Note: to achieve this range, it is likely the chamber will need to be capable of achieving temperatures slightly above and below these target temperatures. Specific design of the chamber is beyond the scope of this specification; however, during the development of this specification, liquid nitrogen (LN2) was utilized to achieve the lower range (-7°C) of the specification.If liquid nitrogen is used, care should be taken to ensure no liquid nitrogen is spilled or splashed directly on the UUT, as it could damage the unit. A schematic of the chamber used is shown in Figure 4.
Minimum amount of time required to hold input speed constant in order to achieve a representative input torque measurement and remove any dynamometer or UUT inertial influence. (Note: the control capability of the dynamometer will likely impact the severity of this influence.) It is important that enough stabilization time passes to eliminate the inertial influence, but it is equally important not to remain at any given input speed long enough to cause the AST and/or oil sump temperature to rise significantly as this will distort the measured input torque. Figure 7 shows an example of the influence input motor controls/inertia may have on the input torque measurement. As noted below, a suitable window should be chosen to guarantee a measurement that is free from any transition influences. The stabilized region is achieved when the instantaneous torque is +2% of the mean torque. In addition to eliminating the inertial influence, it is important to have the test stand controls configured to minimize the overall time required to complete the full stepped sweep (defined in 3.9) data run to minimize the warming of the lubricant and test unit itself.SAE J3039 pdf free download.