The present invention relates to a drive train cooling arrangement for motor vehicles, having a first cooling circuit and a second cooling circuit and having a pump arrangement, by means of which coolant can be fed to the first and the second cooling circuit.
The present invention furthermore relates to a method for operating a cooling arrangement of this kind. There is a known practice in drive trains of motor vehicles of feeding cooling or lubricating oil to subassemblies of a transmission, such as bearings and gearing, by way of injection lubrication. In this case, a pump is generally provided in the region of a transmission sump, and this pump can be driven by means of a drive motor such as an internal combustion engine, for example.
It is furthermore a known practice in the area of drive trains to cool wet multiplate clutches of the kind often used in dual clutch transmissions, for example. In this case, a separate pump is used and is generally likewise coupled to a crankshaft, building up a pump pressure continuously in operation.
To cool such friction clutches, use is generally made of an automatic transmission fluid of relatively low viscosity, whereas “hypoid” oil with a higher viscosity is used for lubrication in many transmissions.
Here, a volume flow of such a cooling or lubricating fluid is generally supplied via electromagnetically controlled valve arrangements. Valves of this kind generally contain spool valves, which make great demands as regards cleanliness during manufacture and assembly.
In the case of drive trains for motor vehicles which additionally have an electric motor as a drive motor (hybrid drive trains), it may also be necessary to cool the electric motor. For this purpose, another cooling arrangement is provided, and this is likewise generally operated with automatic transmission fluid. In this case, an electrically driven coolant pump is generally provided to supply the electric drive motor with coolant in order to allow a purely electric drive mode as well.