2011 FORD KUGA haldex

E100540
Description
Item
Barometric Pressure
A
Base pressure
BDescription
Item
Increased base pressure (preload)
C
Operating pressure
Drive
The hydraulic fluid is drawn from the sump of the
hydraulic system and directed through a filter. The
feed pump pressurises the system and pumps
hydraulic fluid into the pump plungers. This base
pressure of 4 bar presses the rollers for the pump
plungers against the cam disc. At the same time,
hydraulic fluid flows into the working piston. This
eliminates the play in the clutch plates. The Haldex
clutch can respond quickly and distribute the torque
within fractions of a second. The spring force in
the pressure accumulator determines the base pressure of 4 bar and compensates pressure
fluctuations. A compensating spring works in the
opposite direction and prevents the plate discs
becoming blocked by the force of the working
piston. This restricts the transferable torque to
approx. 7 Nm. This value can, however, deviate
slightly due to temperature and/or the difference
in speed between the input and output shafts.
Increased base pressure (preload)
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E100542
Description
Item
Barometric Pressure
A
Base pressure
BDescription
Item
Increased base pressure (preload)
C
Operating pressure
Drive
The pump plungers generate the operating
pressure that is controlled by the control valve as
a function of the difference in speed between the
input and output shafts. The control valve works
progressively from fully open to fully closed. The
fluid pressure can be approx. 67 bar when the
control valve is fully open. The maximum pressure is mechanically controlled by means of the
pressure relief valve.
Design of the 4th generation Haldex
clutch
General overview
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1
2
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4
E115887
Description
Item
Fluid filter
1
All-wheel drive control unit
2Description
Item
Electric feed pump
3
Pressure accumulator
4
The electric feed pump is an axial piston pump
which is more robustly designed than the gerotor
pump in the 3rd generation Haldex. The higher
feed pressure means that the ring piston pump at
the clutch plate assembly, the pressure relief
valves, preload valve and the high pressure valves
are no longer necessary.
The pressure accumulator on the 4th generation
Haldex is larger and is designed for the higher
pressure. The 4th generation Haldex has a larger fluid filter
which contains a non-return valve.
The all-wheel drive control unit no longer contains
a pressure sensor in the 4th generation Haldex.
Pressure control - 4th generation Haldex
clutch
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1
2
3
4
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E114914
Description
Item
Haldex clutch fluid
1
Inlet filter
2
Electric feed pump
3
Filters4
Pressure accumulator
5Description
Item
Control valve
6
Dished washer
7
Ring piston
8
Clutch plate pack
9
Return pressure accumulator
10
Return control valve
11
Full torque is available at any time on the 4th
generation Haldex clutch because the pressure is
not dependent on the difference in the speeds of
rotation. This is used for instance to activate the
Haldex clutch for better traction when moving off.
On the 4th generation Haldex clutch, the preload
function which applied 80 Nm to the plates in the
3rd generation is no longer required.
On request from the control unit and at engine
speeds above 400 rpm, the electric feed pump runs
and maintains the storage pressure at about 30
bar.
A pressure reducing valve acts as a control valve,
allowing the all-wheel drive control unit to control
the pressure with much greater precision. The
all-wheel drive control unit monitors the position and function of the control valve. The control valve
distributes the pressure, depending on the
requirements, across its three outlet openings
(storage pressure, working pressure, return).
From the storage pressure (30 bar) and depending
on the requirements, the control valve regulates a
working pressure of 0 - 17 bar, which is applied to
the ring piston. At 17 bar working pressure, the
maximum torque of 1000 Nm is transferred to the
rear wheels. The all-wheel drive control unit
ensures the best possible performance under all
driving conditions, for all road conditions and
independent of the speed.
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