27
Single pipe gas-pressure shock absorber
With the single pipe gas-pressure shock
absorber, the working chamber and the oil
reservoir are located in a single cylinder.
Volumetric changes caused by the piston rod
and the temperature changes in the oil are
compensated by another gas chamber which
is separated from the working cylinder by a
dividing piston. The level of pressure in the
gas chamber is approx. 25 - 30 bar and must
be able to sustain the damping forces during
compression.
The damping valves for compression and
rebound are integrated into the piston.
Comparison of single/dual pipe gas-pressure shock absorbers
Dual pipe gas-pressure shock
absorberSingle pipe gas-pressure shock
absorber
Valve function The tendency towards cavitation
is reduced by the gas pressure in
the oil reservoirMinimal tendency towards
cavitation thanks to high gas
pressure and separation of oil and
gas
Characteristic
curvesAny, due to separate valves for
compression and reboundDependant on the gas pressure
during compression
Short damping
strokesGood Better
Friction Low Higher due to seal under pressure
Design Greater diameter Longer due to gas chamber in the
cylinder
Installation
positionApproximately vertical Any
Weight Heavier Lighter
242_082
Piston with damping
valves
Dividing piston
Gas chamber
Damper valves
53
0,5 2,5 4,5
0°
70°
0
Function
A ring magnet is connected to the axle of the
sensor crank (rotor).
A hall IC is positioned eccentrically between a
two-piece iron core (stator). It forms a single
unit together with the evaluation electronics.
Depending on the position of the ring
magnet, the magnetic Þeld which penetrates
the Hall IC changes.
The resulting Hall signal is converted by the
evaluation electronics into a voltage signal
proportional to the angle. The control unit
J197 uses this analogue voltage signal to
determine the current vehicle level.
242_062242_061
242_060
Deßection 35¡ right No deßection
Deßection 35¡ left
Rotor
(ring magnet)
Stator
(divided iron core)
N
SN
S
N
S
Angle VoltsHall IC
Average setting
approximate reference level position
242_063
The angle sensor described here is
also used for the automatic
headlight range control system.
A total of 3 sensors are Þtted into
vehicles with automatic headlight
range control.
