Patent ID: 7509806

Claim:
A method for optimizing the action of the engine brake in a drive unit in a motor vehicle comprising: providing an internal combustion engine comprising a crankshaft; providing an exhaust gas turbine along an exhaust gas flow of the internal combustion engine for the conversion of exhaust gas energy into drive energy, the exhaust gas turbine being operably connected to the crankshaft via a transfer device; providing a hydrodynamic coupling comprising a primary wheel and a secondary wheel which is disposed in the transfer device, wherein the secondary wheel is coupled with the crankshaft and the primary wheel is coupled with the exhaust gas turbine; operating the exhaust gas turbine at a first working point during a braking operation, the first working point having a maximum acceptable limiting speed n max-5 of the exhaust gas turbine with a minimum outputtable moment M 5 , and operating the exhaust gas turbine at a second working point during a partial load or thrust operation, the second working point having a minimum speed n min-5 and a minimum receivable moment M min-5 , wherein adjusting of the first and second working points is conducted via the hydrodynamic coupling, wherein the transferable moment of the hydrodynamic coupling corresponds to the minimum outputtable moment M 5 or the minimum receivable moment M min-5 that is transferred by the exhaust gas turbine over most of the speed difference over time, taking into consideration the gear ratio of the transfer elements in the transfer device relative to the exhaust gas turbine, wherein the hydrodynamic coupling has a moment transfer equal to the minimum outputtable moment M 5 during the braking operation, and wherein the exhaust gas turbine has a control speed that is produced whereby the control speed is equal to the minimum speed n min-5 that is kept as small as possible during the partial load or thrust operation.