| 摘要 |
The use of anti-friction ball bearings in a unique arrangement does not require the use of lubricating oil from the internal combustion engine lubricating system and permits close coupling of the bearings and a compact turbocharger. A turbocharger bearing housing forms a coolant jacket with an inner bearing engaging portion that has two bearing engagement surfaces engaged with the outer races of two anti-friction bearings whose inner races carry rotating shaft, turbine and compressor of the turbocharger. The anti-friction bearings are, preferably, angular contact ball bearings, and the two bearing engagement surfaces of the bearing housing are closely spaced, providing a turbocharger shaft of minimal length and substantially reducing the thermal expansion of the shaft. The coolant jacket protects the anti-friction bearings from exposure to the extreme heat of the exhaust gas driven turbine, notwithstanding their increased proximity due to the shortened turbocharger shaft. In addition, an external motor-generator may be carried by the compact turbocharger, and its motor may be connected to the turbocharger rotor assembly by a permanent, solid connector and stay connected throughout the entire operating range of the turbocharger. In such assembly, the electronic motor-generator control is mounted on the motor housing and energizes the motor from battery power during the engine acceleration period up to approximately the torque peak speed; thereafter, the control changes to a generator mode when excess energy is available in the engine exhaust gas.
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