Patent ID: 8888659
Filing Date: 2014-11-18
Classification: B60K,B60W,F16D,Y10T

Abstract:
1. A method for operating a motor vehicle drive train device with a drive engine ( 15 ) and a drive train ( 10 ) for driving axle wheels ( 31 , 33 ), the drive train ( 10 ) comprising a first coupling unit ( 11 ) in the form of a clutch arranged close to the drive engine ( 15 ), a gear box ( 20 ) for changing the power transmission ratio for driving the axle wheels ( 31 , 33 ), a differential transmission ( 27 ) arranged between, and connected to, the axle wheels ( 31 , 33 ) via drive wheel shafts ( 30 , 32 ), a drive shaft ( 23 ) extending between the gear box ( 20 ) and the differential transmission ( 27 ), and second coupling units ( 12 , 13 ) arranged in the drive wheel shafts ( 30 , 32 ), and with a control unit ( 14 ) for controlling the first and second coupling units ( 11 , 12 , 13 ), the control unit ( 14 ) having an overrun operating mode in which, in a first overrun condition the drive engine ( 15 ) is disconnected from the drive train ( 10 ) by opening the first coupling unit ( 11 ) close to the engine to avoid engine braking, the control unit ( 14 ) being further provided to disconnect, in a second overrun condition the drive train ( 10 ) also from the drive wheels ( 31 , 33 ) by additionally opening the second coupling units ( 12 , 13 ) which are arranged in the drive wheel shafts ( 30 , 32 ), the first coupling unit ( 11 ) and the second coupling units ( 12 , 13 ) when opened disconnecting the drive train including the gearbox ( 20 ) and also the differential transmission ( 27 ) from the drive wheels ( 31 , 33 ) thereby avoiding churning losses in the gear box as well as in the differential transmission, the method comprising the steps of: opening the first coupling unit ( 11 ), in an overrun operating mode, at a first point so that the drive engine ( 15 ) is disconnected from a power transmission part ( 16 ) of the drive train ( 10 ), and, at a second point, opening the second coupling units ( 12 , 13 ) for disconnecting the drive wheels ( 29 , 31 ) from the power transmission part ( 16 ) of the drive train ( 10 ).