Re: 2007 HiHy HP to the wheel's. Dyno?
The 2004 Prius was studied by Oak Ridge National Labs for the DOE. There was a 3.2 HP peak mechanical loss in the PSD. The Highlander has a similar Power Split Device so you can get an idea of the loss magnitude:
5.1 FINDINGS AND OBSERVATIONS
Initial vehicle-level data collected at ANL shows that the data acquisition scheme would provide adequate data to determine efficiencies of the basic hybrid electric drive system components such as the motor, generator, and inverter. It must reflect patterns and control schemes during various parts of a driving cycle. Sensor calibrations and equipment checks are needed to validate the data. This work is currently proceeding. Component-level testing at ORNL revealed that gearbox related friction losses were found to be significant. These losses are approximately 2.4 kW at a motor speed of 6000 rpm. The predominant loss of about 1.6 kW is associated with the main reduction gears and drive chain, while the motor, power split device, and generator yielded losses of about 0.8 kW. Gear train losses are primarily associated with oil splashing within the hybrid drive housing and oil slinging from the generator and motor rotors to provide needed lubrication and removal of excess heat. These losses, which are summarized in Table 5.1, were determined with the lubricating oil at or near room temperature (about 25°C). The tests also revealed that overall losses decreased about 20% when the temperature of the lubricating oil increased from 27 to 80°C. This finding indicates that total losses for the hybrid electric drive system equal approximately 1.9 kW at a lubricating oil temperature of 80°C.
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