Lubrication System
To meet the oiling requirements of the N52, a new "volumetric-flow controlled" oil pump is utilized. Systems such as VANOS require a large volume of oil, particularly at low engine speeds.
To keep up with the volume requirements, a conventional oil pump would need to be 3 times as large as the new oil pump design. A larger oil pump would also consume excess energy and therefore the new pump design allows
- Increased power output
- Reduced weight
- Optimized fuel consumption
- Reduced exhaust emissions
Scheme 56
The savings potential of the new optimized pump system is a good reason to employ this new design.
The tasks of the engine oiling system includes
- The lubrication of friction surfaces in the engine
- The cooling of part subject to high load
- Carrying away abrasive particles
- Provides a hydraulic control medium (for VANOS etc)
- Protection against corrosion
The VANOS requires a large volume of oil particularly for the purpose of adjusting the camshaft angle. However, it requires no oil flow when the VANOS retains the set camshaft angle.
The oil requirement therefore depends on the extent of the required adjustment.
Conventional oil pumps produce the oil pressure necessary for the greatest possible oil flow that can occur in the engine. In many operating situations this situation represents unnecessary energy consumption through the oil pump and excessive wear of the oil.
The Valvetronic II and hot idle operation, therefore necessitate a new optimized pump system.
The highest control demands are placed on the double VANOS at idle speed and small valve lift rates. The adaptation requirement for the start of opening of the valves is proportionally the greatest under these operating conditions.
For the oil pump this means that it must deliver a large volume of oil to the VANOS units at relatively low engine speeds.
Scheme 57
To meet these demands, a conventional oil pump would have to be dimensioned 3 times as large as the oil pump used on the N52. It would also take up correspondingly more drive energy.
The N52 is equipped with a volumetric-flow controlled oil pump. This type of pump deliver only as much oil as is necessary under the respective engine operating conditions. No surplus quantities of oil are delivered in low load operating ranges. This reduces the fuel consumption of the engine and slows down the oil wear rate.
The pump is designed as a slide valve-type vane pump. In delivery mode, the pump shaft is positioned off-center in the housing and the vanes are displaced radially during rotation. As a result, the vanes form chambers of differing volume. The oil is drawn in as the volume increases and, conversely, expelled into the oil channels as the volume decreases.
