Patent ID: 8465392

Claim:
A method of operating a vehicle hybrid drive train ( 1 ) comprising an internal combustion engine ( 2 ) and an electric machine ( 3 ) which are connected to the vehicle hybrid drive train such that torque from both the internal combustion engine and the electric machine is transmittable to a drive output ( 4 ) of the vehicle hybrid drive train ( 1 ), a clutch device ( 5 ) arranged between the internal combustion engine ( 2 ) and the electric machine ( 3 ) such that the internal combustion engine is roationally fixable to the electric machine, an oil pump device ( 7 ) arranged in the vehicle hybrid drive train ( 1 ), downstream of the clutch device ( 5 ), in relation to the internal combustion engine ( 2 ), and drivable by both the internal combustion engine ( 2 ) and by the electric machine ( 3 ), and a transmission device ( 6 ) which comprises a plurality of shifting elements for producing various gear ratios and which is supplied with hydraulic fluid by the oil pump device ( 7 ) in an operating-status-dependent manner such that a speed of the electric machine ( 3 ) is set, independently of a speed of the internal combustion engine ( 2 ), in order to supply the transmission device ( 6 ), in each case, with a hydraulic fluid volume flow required for an operating point of the transmission device ( 6 ) present at the time, the method comprising the steps of: corresponding the speed of the electric machine ( 3 ) to an at-rest speed value which is lower than an idling speed of the internal combustion engine ( 2 ), when the vehicle is at least approximately at rest, such that the oil pump device ( 7 ) driven by the electric machine ( 3 ) maintains the shifting elements in an at least partially engaged condition so as to maintain a current operating status of the transmission device ( 6 ), and increasing the speed of the electric machine ( 3 ), in a range when the vehicle is at rest, when there is at least one of a shift demand for a gear change from a starting gear to a higher gear step and a shift demand for a gear change from a higher gear step to a starting gear.