BMW N55, Manual, Page: 23 / 100

Electrionic Volume-controlled Oil Pump
A modified version of the volume control oil pump of the N54 engine is used. For the first
time a Duroplast reciprocating slide valve is installed. The volumetric flow control system
operating principle of the oil pump is described in the E71 X6 training material under the
”N63 Engine” available on TIS and ICP.
This type of pump delivers 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 operating mode reduces the pump work and therefore the fuel consumption
of the engine while also slowing down the oil aging process. 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
expelled into the oil galleries as the volume decreases.
The oil pressure in the system (downstream of the oil filter) acts on the slide against the
force of a compression springs in the control oil chamber. The slide element rotates
about a pivot axis.
N55, oil pump
Index Explanation Index Explanation
1
Control oil chamber
7
Housing
2
Pressure limiting valve
8
Hole for pressure control valve
3
Rotor
9
Damping oil chamber
4
Vane
10
Compression spring (2x)
5
Duroplast slide valve
11
Pivot axis of rotation
6
Inner rotor
23
N55 Engine