BMW S58, Owner'S Handbook Manual

Page: 50 / 102

S58�Engine
7.�Oil�Supply
44
Index Explanation
5 Sprocket
6 Control�line�of�map�control�valve�(map�control�pressure)
7 Oil�pump�drive
8 Control�plunger
9 Piston�pressure�side�of�the�axially�movable�impeller
10 Oil�duct�into�the�engine�block�(unfiltered�oil)
11 Control�piston�spring
12 Second�level�control�pressure
13 Oil�duct�to�the�piston�pressure�side
7.3.2.�Minimum�delivery
If�the�data-map�control�valve�directs�the�data-map�control�pressure�via�the�control�line�(6)�to�the�larger
face�of�the�control�piston�(8),�the�data-map�control�pressure�overcomes�the�second-level�control
pressure�due�to�the�difference�in�surface�area�on�the�control�piston�(8).�The�map�control�pressure
presses�against�the�control�piston�spring�and�thus�adjusts�the�control�piston�(8)�toward�minimum
delivery.�By�being�moved�to�the�minimum�delivery�position,�the�control�piston�(8)�opens�the�oil�duct
to�the�piston�pressure�side�(15).�The�filtered�oil�from�the�oil�duct�(12)�is�now�conveyed�to�the�front
piston�pressure�side�(9)�of�the�axially�movable�impeller�(3).�On�account�of�the�axial�shift�caused�by�the
oil�pressure,�the�planes�of�contact�of�the�external�gear�wheels�are�reduced�and�the�delivery�rate�of�the
filtered�oil�decreases.�The�oil�on�the�rear�piston�pressure�side�can�flow�back�into�the�sump�via�the�oil
duct�outlet�(13)�and�the�oil�return�flow�(14).