SSP 331 Variable Anti-roll Bars on the Touareg - Volkspage

Nitrogen gasDiaphragmHow it worksWhen the hydraulic fluid is pumped into thepressure accumulator via thenon-return valve, pressure in the system rises inrelation to the volume of fluid pumped. Thenitrogen gasis compressed and the volume of the gaschamber diminishes. The fluid volume rises at thesame rate until the cut-off pressure is reached.Pressure in the accumulator is maintained by thenon-return valve and is supplied to theanti-<strong>roll</strong> bars via a duct.Hydraulic fluidS<strong>331</strong>_116Pressure accumulatorNon-return valveHydraulic unit pressuresensor for anti-<strong>roll</strong> baruncoupling<strong>Anti</strong>-<strong>roll</strong> baruncoupling motorElectric motorS<strong>331</strong>_156To protect the pressure accumulator, pressure in the system must be over 70 bar during thecoupling operation.17

Design and functionHydraulic unit pressure sensor for anti-<strong>roll</strong> bar uncoupling G486S<strong>331</strong>_056S<strong>331</strong>_050The hydraulic unit pressure sensor for anti-<strong>roll</strong>bar uncoupling monitors system pressure over arange of 0 bar to 250 bar.The pressure accumulator is recharged if thepressure drops below a minimum of 90 bar whenthe anti-<strong>roll</strong> bars are uncoupled, or when theanti-<strong>roll</strong> bars are coupled and the gearbox isswitched to "low".DesignThe sensor consists of the sensor electronics (b)and a piezoelectronic element (a) which reacts tothe hydraulic fluid pressure.baS<strong>331</strong>_10418

1How it worksThe hydraulic fluid pressing on the piezoelectricelement changes the charge distribution in theelement.Without the action of pressure, the charges havean even distribution (1). If pressure starts to act,the charges change their physical position (2).This generates an electrical voltage.S<strong>331</strong>_106The higher the pressure, the more the chargesare separated. The voltage rises. It is amplifiedby the electronic circuits and sent as a signal tothe anti-<strong>roll</strong> bar control unit.2The voltage intensity is therefore directlyproportional to the hydraulic pressure.S<strong>331</strong>_10819

Design and function<strong>Anti</strong>-<strong>roll</strong> bar uncoupling motor V326S<strong>331</strong>_058S<strong>331</strong>_012Coupling piece flangeThe anti-<strong>roll</strong> bar uncoupling motor is driven bythe electric motor via the coupling piece.It draws hydraulic fluid out of the expansion tankand pumps it to the pressure accumulator via anon-return valve.Oil flow in the pumpTo pressure accumulatorCoupling pieceGear wheelsCouplingpiece flangeIntake duct fromexpansion tankS<strong>331</strong>_10220

S<strong>331</strong>_120To pressureaccumulatorPressure chamberHousing wallHow it worksThe anti-<strong>roll</strong> bar uncoupling motor is a gearpump. The opposing rotary motion of the twogear wheels pumps the hydraulic fluid along theoutside of the housing wall.A definite volume of hydraulic fluid is taken independing on the volumetric space between theteeth and the housing wall. This volume is thenpumped in the direction of rotation of the gearwheel.Intake duct fromexpansion tankGear wheelsS<strong>331</strong>_080The two gear wheels intermesh in the middle.The volumetric space becomes smaller and thehydraulic fluid is pressed out of the volumetricspace. Pressure then rises in the pressurechamber. When the pressure has risensufficiently, the non-return valve opens and thehydraulic fluid is pumped to the pressureaccumulator.S<strong>331</strong>_118Volumetric space21

Design and functionExpansion tankConnection forvent lineConnection forsupply lineS<strong>331</strong>_056S<strong>331</strong>_016Connection tosupply unitThe expansion tank is inserted onto the supplyunit and secured by a hose clamp. It is designedto prevent the pump from running dry in anydriving situation.There is no min./max. marking. Oil level ischecked through the supply line using a modifiedcustomary commercial plastic bottle (refer to the"Service " section on page 33).There are two connections on top of theexpansion tank: one is for the vent line and theother is for the supply line.22

Electric motorS<strong>331</strong>_046S<strong>331</strong>_056The electric motor is a direct-current motor with apermanent magnet. It is also termed apermanently excited collector motor.Due to its linear characteristic curves, it is anadaptable and readily cont<strong>roll</strong>able drive.<strong>Anti</strong>-<strong>roll</strong> bar control unit J742The fitting location for the control unit is in theluggage compartment under the spare wheelcover.It is inserted on end in a moulded foam packingwith the connector output pointing upwards.The anti-<strong>roll</strong> bar control unit is connected to thevehicle's drivetrain CAN databus.S<strong>331</strong>_010It evaluates the following signals:● system pressure● switching state of the anti-<strong>roll</strong> bar● anti-<strong>roll</strong> bar uncoupling button signalIt receives the following signals:● road speed● lateral acceleration● gearbox mode (high or low)The control unit sends a signal to the actuatorsdepending on the result of evaluation.23

Design and function<strong>Anti</strong>-<strong>roll</strong> barThe key component of the variable anti-<strong>roll</strong> bar isthe hydraulically operated actuator. It ispositioned in the middle of the anti-<strong>roll</strong> bar.The actuator contains a claw coupling whichcouples and uncouples the anti-<strong>roll</strong> bar arms.Front axle anti-<strong>roll</strong> bar<strong>Anti</strong>-<strong>roll</strong> bar armActuator<strong>Anti</strong>-<strong>roll</strong> bar armS<strong>331</strong>_084Rear axle anti-<strong>roll</strong> bar<strong>Anti</strong>-<strong>roll</strong> bar armActuator<strong>Anti</strong>-<strong>roll</strong> bar armS<strong>331</strong>_08224

Claw couplingThe hydraulically operated claw couplingconsists of input-side and output-side couplingelements, a switching element, a fail-safe springand an anti-<strong>roll</strong> bar uncoupling sensorpositioned on the housing.Closed couplingPressurechamber 1Axial needlebearingPressurechamber 2Input-sideS<strong>331</strong>_086coupling elementFail-safe springSwitching element<strong>Anti</strong>-<strong>roll</strong> bar uncoupling sensorOutput-sidecoupling elementOpen couplingTwist angle approx. 34°Pressurechamber 1S<strong>331</strong>_088Left anti-<strong>roll</strong>bar armPressurechamber 2Right anti-<strong>roll</strong>bar armMagnetic pin inswitching element25

Design and functionSwitching elementInput-side couplingelement (with right anti-<strong>roll</strong>bar arm fixed)Switchingelement tonguesRight anti-<strong>roll</strong>bar armS<strong>331</strong>_112Left anti-<strong>roll</strong>bar armOutput-side coupling element (with leftanti-<strong>roll</strong> bar arm fixed to the housing)Switching elementThe switching element is free to move along itsaxis. Its axial position is dependent on thepressure applied and in its closed position, theinput-side and output-side coupling elements arefully interlocked.The switching element does not retractcompletely and the two tongues overlap thecoupling elements at all times. This allows acoupling operation in any driving situation.In the figure above, the two switching elementtongues are depicted fully retracted from thecoupling elements. This is purely to show thedesign of the switching element.<strong>Anti</strong>-<strong>roll</strong> bar uncoupling sensors G484 and G485S<strong>331</strong>_110The "anti-<strong>roll</strong> bar coupled" switching position issignalled when the anti-<strong>roll</strong> bar sensor contactsthe magnetic pin. The anti-<strong>roll</strong> bar uncouplingsensor signal is required by the anti-<strong>roll</strong> barcontrol unit to monitor the system.26

Fail-safe springThe fail-safe spring is a coil spring which forcesthe anti-<strong>roll</strong> bar closed if there are faults in thehydraulic supply or electrical defects.An axial needle bearing is fitted between thefail-safe spring and the switching element tominimise wear.<strong>Anti</strong>-<strong>roll</strong> bar uncoupling button E484The anti-<strong>roll</strong> bar uncoupling button is locatedcentrally on the centre console. It sends the signalindicating the driver's command to couple oruncouple the anti-<strong>roll</strong> bars to the anti-<strong>roll</strong> barcontrol unit.If the driver presses the button several times, thecoupling or uncoupling operation is cancelled.If the button is pressed for longer than 30seconds, this is detected as a system fault.An entry is made in the control unit fault memory.The anti-<strong>roll</strong> bars remain coupled.The anti-<strong>roll</strong> bar uncoupling button is fitted withan anti-<strong>roll</strong> bar uncoupling warning lamp.Button on vehicle equipped with steel suspensionButton on vehicle equipped with air suspension<strong>Anti</strong>-<strong>roll</strong> baruncoupling buttonS<strong>331</strong>_033<strong>Anti</strong>-<strong>roll</strong> bar uncouplingwarning lamp<strong>Anti</strong>-<strong>roll</strong> baruncoupling buttonS<strong>331</strong>_013<strong>Anti</strong>-<strong>roll</strong> bar uncouplingwarning lamp27

Design and function<strong>Anti</strong>-<strong>roll</strong> bar uncoupling warning lamp K221Warning lampS<strong>331</strong>_122The anti-<strong>roll</strong> bar uncoupling warning lamp K221is located in the anti-<strong>roll</strong> bar uncoupling buttonE484.If the anti-<strong>roll</strong> bars are uncoupled, the displayappears continuously.The warning lamp flashes during the coupling oruncoupling operation.Displays in the dash panel insertThe current anti-<strong>roll</strong> bar switching state isdisplayed in the dash panel insert.The symbols are different depending on thevehicle's equipment.On the Highline dash panel insert, the symbolsare displayed in pixel graphics; on the Premiumequipment level, they appear on a TFT screen.HighlineequipmentlevelPremiumequipmentlevelS<strong>331</strong>_16328

UncouplingHighline displayThe coupling operation display flashes for theentire duration of the operation. When theanti-<strong>roll</strong> bars are uncoupled, the couplingoperation display is continuously lit.Couplingopertion displayCouplingThe coupling operation display flashes for theentire duration of the operation.The display disappears only when the operationis completed and the anti-<strong>roll</strong> bars are coupled.S<strong>331</strong>_078Gearbox modedisplayPremium displayCouplingoperation displayS<strong>331</strong>_074Gearbox modedisplay29

Design and functionHighline displayFault displayFlagIf a fault occurs during the uncoupling orcoupling operation, it is displayed by a flag.At the same time, the fault display "System faultworkshop" appears.It is no longer possible to uncouple the anti-<strong>roll</strong>bars. The vehicle can still be driven.S<strong>331</strong>_076Fault displayPremium displayFlagS<strong>331</strong>_072FlagFault displayS<strong>331</strong>_09430

System overviewSystem overviewSensorsActuatorsE484<strong>Anti</strong>-<strong>roll</strong> bar uncoupling buttonK221<strong>Anti</strong>-<strong>roll</strong> bar uncoupling warninglampG484Front axle anti-<strong>roll</strong> bar uncouplingsensorN399Front axle anti-<strong>roll</strong> baruncoupling switch valveG485Rear axle anti-<strong>roll</strong> bar uncouplingsensorN400 Rear axle anti-<strong>roll</strong> baruncoupling switch valveJ742<strong>Anti</strong>-<strong>roll</strong> bar control unitG486Hydraulic unit pressure sensorfor anti-<strong>roll</strong> bar uncouplingV326<strong>Anti</strong>-<strong>roll</strong> bar uncoupling motorDrivetrain CAN data busGearbox mode, high or lowRoad speedLateral accelerationJ285Dash panel insert(gateway)S<strong>331</strong>_10031

Function diagramTerm. 30Term. 15S S S SG484G485K221E484J742S<strong>331</strong>_026V326 N400 N399 G486ABE484G484G485G486J742K221- Drivetrain CAN databus - Low- Drivetrain CAN databus - High<strong>Anti</strong>-<strong>roll</strong> bar uncoupling buttonFront axle anti-<strong>roll</strong> bar uncoupling sensorRear axle anti-<strong>roll</strong> bar uncoupling sensorHydraulic unit pressure sensor for anti-<strong>roll</strong> baruncoupling<strong>Anti</strong>-<strong>roll</strong> bar control unit<strong>Anti</strong>-<strong>roll</strong> bar uncoupling warning lampN399 Front axle anti-<strong>roll</strong> bar uncoupling switch valveN400 Rear axle anti-<strong>roll</strong> bar uncoupling switch valveV326 <strong>Anti</strong>-<strong>roll</strong> bar uncoupling motorColour codes/key= Input signal= Output signal= Positive= Earth= Drivetrain CAN databus32

ServiceChecking the oil levelThe filler hole and plug for filling and checkingthe oil level is located behind the left-sidetail-light.Before the oil level can be checked, the left-sidetail-lamp must be removed and the system mustbe depressurised, e.g. using the VAS 5051Diagnosis Testing and Information System.S<strong>331</strong>_136Filler holePlugMarkPlastic bottle markS<strong>331</strong>_140S<strong>331</strong>_138When checking the oil level or filling the system with oil, insert the plastic bottle hose into the filler holeup to the mark.● The system may only be filled with central hydraulic system and power steering gear oilG002000.● Please read the instructions in ELSA (Electronic Service Information System) for setting themark, checking the oil level and filling the system with oil.33

ServiceVenting the systemBefore the system can be vented, it must beconnected to the VAS 5051 Diagnosis Testing andInformation System, for example, anddepressurised.Ventilation nippleBefore venting, remove the dust caps andconnect a transparent plastic hose to theventilation nipple. As high pressures occur duringthe ventilation operation, the hose must besecured by a hose clamp.Ventilation nippleHose clampS<strong>331</strong>_142Loosen the two ventilation nipples. The systemcan then be vented according to the instructionsfor using the VAS 5051 Diagnosis Testing andInformation System.After ventilation is completed, tighten the nipplesand remove the plastic hose.S<strong>331</strong>_144Ventilation nipplePlastic hose● Please read the instructions in the ELSA (Electronic Service Information System) carefully forventing the system and for the size of the plastic hose required.● Please remember to check the oil level before and after the venting operations.● When working on the running gear, e.g. removing a suspension strut or tightening bolts onrubber metal bearings, couple the anti-<strong>roll</strong> bars to prevent them from uncoupling due toinadvertent switching and injuring service personnel, and to avoid damaging the runninggear.34

Test your knowledge1. How are anti-<strong>roll</strong> bars uncoupled on the Touareg?a) mechanicallyb) hydraulically2. When can the driver carry out an uncoupling command?a) When the vehicle road speed is below 40 km/h and pressure in the pressure accumulator is below 70 barto prevent destroying the gas bubble in the pressure accumulator.b) When the speed is above 50 km/h, lateral acceleration is greater than 0.7 g and the pump motor isrunning.c) When the vehicle road speed is below 40 km/h, lateral acceleration is less than 0.5 g and the control unitis not in fault mode.3. The claw coupling consists of two coupling elements, a switching element, a fail-safe spring and ananti-<strong>roll</strong> bar uncoupling sensor. Why does the switching element not retract completely beyond theoverlap of the tongues when the anti-<strong>roll</strong> bar is uncoupled?a) To allow coupling in every driving situation.b) To avoid exceeding the defined maximum torsional twist of 60 mm.c) So that the anti-<strong>roll</strong> uncoupling sensor can monitor the system in every situation.Answers1.) b; 2.) c; 3.) a35

<strong>331</strong>© VOLKSWAGEN AG, Wolfsburg, VK-21 Service TrainingAll rights reserved. Technical specifications subject to change without notice.000.2811.47.20 Technical status 09/04❀ This paper is produced from pulpthat has not been bleached with chlorine.