Figure: haldex generation 1 (13KB)
The design of the Haldex LSC gen. I, II, and III is based on a Swedish patent acquired by the Haldex Group.
The unique design of the Haldex LSC comprises three functional parts
- The hydraulic pump driven by the slip between the axles/wheels.
- The wet multi-plate clutch
- The controllable throttle valve with its electronics.
The unit can be viewed as a hydraulic pump in which the housing and an annular piston are connected to one shaft and a piston actuator is connected to the other.
The two shafts are connected via the wet multi-plate clutch pack, normally unloaded and thus transferring no torque between the shafts.
When both shafts are rotating at the same speed, there is no pumping action. When a speed difference occurs, the pumping starts immediately to generate oil flow. It is a piston pump, so there is a virtually instant reaction with no low-speed pumping loss.
The oil flows to a clutch piston, compressing the clutch pack and braking the speed difference between the axles. The oil returns to the reservoir via a controllable valve, which adjusts the oil pressure and the force on the clutch package.
In traction/high slip conditions, a high pressure is delivered: in tight curves (i.e. parking), or at high speeds - a much lower pressure is provided.
Haldex Generation I and II based all wheel drive system is reactive. The coupling activates after a wheelspin is detected. However, the reaction is very quick and just 1/4 of a wheel turn is needed to engage all wheel drive. Electronics is capable of lowering the oil pressure only (when parking, ABS working, the handbrake is pulled, etc.), but cannot pre-tension the clutch.
Under normal driving conditions (driving at the constant speed, no silppage), the torque distribution is 90/10 front to rear. When the clutch is locked, torque is evently distributed between the axles (50/50).
Figure: haldex clutch (63KB)
Figure: haldex clutch (18KB)
Figure: haldex coupling generation 1 multi plate clutch (46KB)
Figure: haldex generation 1 (74KB)
Figure: haldex generation 1 (85KB)
Figure: haldex generation 1 (117KB)
Figure: haldex generation 1 (83KB)
Figure: haldex generation 1 (45KB)
Figure: haldex generation 1 (62KB)
Figure: haldex generation 1 diagram of the oil pressure system (52KB)
Figure: haldex generation 1 ecu mastervalve (31KB)
Figure: haldex generation 1 skoda octavia (9KB)
More info: http://audittrs.wordpress.com/2010/12/07/haldex-service-training-self-study-program/