Service. Self-Study Programme 277 The Phaeton Chassis Design and function In top form, the Phaeton chassis fulfils even the most challenging demands on comfort and driving dynamics. Through its components, including - Speed dependent power-assisted steering, Four-link front suspension, Trapezoidal wishbone rear suspension and ESP with braking assistant, it achieves an important contribution towards active vehicle safety. S277_033 NEW The self-study programme presents the design and operation of new developments! Contents will not be updated. 2 Current testing, adjustment and repair instructions may be found in the appropriate service material. Caution Note At a Glance Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 Front axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Rear axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Steering system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Brake system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32 Wheels and tyres. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46 Tyre pressure monitor . . . . . . . . . . . . . . . . . . . . . . . . . .48 Check your Knowledge . . . . . . . . . . . . . . . . . . . . . . . .59 3 Introduction The chassis ● ● ● Trapezoidal wishbone rear suspension with 1612 mm track width Front and rear anti-roll bars ● Independent wheel suspension front and rear ● 4 Four-link front suspension with 1628 mm track width 4-corner air suspension with regulated damping S277_002 ● ● ● ● ● Foot parking brake ● Braking assistant Speed dependent power-assisted steering Ventilated disc brakes Tyre pressure monitor, optional Electronic Stability Programme, Bosch 5.7 5 Front axle The front axle S277_129 The Phaeton's front axle is equipped with four-link suspension. The multitude of guide elements produces the following advantages: - 6 Complete isolation of drive forces from the steering High steering precision through optimised positioning of the pivot axis Good driving comfort Exceptional anti-squat and anti-dive performance The component overview Bearing block aluminium cast part The upper suspension links (front and rear) aluminium forged parts Wheel bearing housing steel cast part Subframe made of hydroformed steel Guide link aluminium forged part Anti-roll bar steel S277_010 Bearing link steel forged part 7 Front axle The bolted wheel bearing The wheel bearings are not pressed into the wheel bearing housing as was the practice up to now, but bolted directly to the wheel bearing housing as a unit (bearing and bearing housing). Wheel hub Wheel bearing housing Bolted connection This enables the wheel bearing to be installed without removing the pivot bearing or jointed shaft. Wheel bearing Bolted connection S277_044 The anti-roll bar Depending on the engine, the Phaeton has either a solid anti-roll bar of 35 mm diameter or a tubular anti-roll bar of 35 mm diameter and 6 mm wall thickness. The intermediate rubber bearings and aluminium pipe clamps are vulcanised on in this design and cannot be replaced. Rubber bearing with aluminium pipe clamps This support arrangement, which was designed to have radially rigid and rotationally flexible characteristics, prevents noise and wear. S277_025 8 The subframe The high-pressure formed subframe of tubular steel is bolted to the body using rubber-metal bearings. This flexible connection keeps the body free of forces and impacts that the chassis introduces. The additional bolted brace ensures ample transverse rigidity. Brace S277_026 The connection of the air suspension strut to the suspension link The air suspension strut is attached to the bearing link with a rubber-metal bearing. Air suspension strut Bearing link S277_037 9 Front axle The virtual steering axis 1-4 Directions of the suspension links R Wheel centre point A Wheel contact point n Trail nv Castor offset p Scrub radius a Road feedback lever arm Point AS = Piercing point of the steering axis on the roadway S277_029 With the four-link front suspension, the steering axis does not run through the upper and lower joints on the wheel bearing housing as with previously familiar front axle designs. Instead it runs through the intersection points formed by extrapolating the connection lines of the two upper and two lower suspension link joints respectively. Thus, the suspension link axis is in free space and does not change position at full steering lock. This is why we refer to it as the virtual steering axis. 10 This arrangement enables the steering axis to be placed close to the wheel centre plane. This has a positive effect especially on the scrub radius and the road feedback lever arm, and thus produces advantages in driving behaviour. The full steering lock positions This axle design allows the virtual steering axis, around which the wheel moves and whose position determines the castor angle and the steering swivel inclination, to be shifted much further out. By optimising the axle geometry, it is possible to completely isolate torque steer effects on the steering. S277_070 Link position for left curve Since the wheels are located using four ball sockets on the respective transverse links, the pivot axis can run approximately in the wheel centre independently of construction space requirements. The pivot axis is designed to change position according to the steering movements. The defined movement of the axis when steering reduces the space requirements in comparison to conventional axle systems with fixed space steering axes. The virtual steering axis changes position depending on the steering movements. S277_040 Link position for straight driving S277_072 Link position for right curve 11 Rear axle The rear axle, front wheel drive In the Phaeton, the rear axle is designed with trapezoidal (unequal length) wishbone suspension. All wheel location elements are mounted to a subframe that is rigid in bending, torsion and warping. This is connected to the body using largedimensioned rubber bearings. This type of structure achieves exact wheel location and good ride. S277_101 The wheel hub Wheel bearing housing Instead of the bolted constant velocity (CV) joint pivot, the wheel bearing is prestressed with a stub axle. Bolted connection The rear axle for front wheel drive vehicles is equivalent to the axle for all-wheel drive vehicles. Rear axle drive and jointed shafts are not used. Stub axle Bolted connection S277_046 12 The rear axle 4-motion In the 4-motion version, the subframe holds the rear differential at three points. Therefore, the rear differential is doubly isolated from the body. S277_016 13 Rear axle Steel subframe Transverse link aluminium forged part Rubber-metal bearing Axle link aluminium cast part S277_068 Bolted joint for camber correction Bolted joint for track correction Wheel bearing housing Track rod Coupler Integrating a coupler into the hub carrier connection and using a track rod has optimised the toe-in behaviour of the rear axle. 14 S277_018 In particular, the passive steering properties and noise insulation have consistently improved. The anti-roll bar Rubber bearings An anti-roll bar made of 20 mm solid material has been installed on the rear axle. The rubber bearings are vulcanised on as in the front axle. This design is free of noise and wear. S277_031 The wheel bearing housing With the rear axle, as with the front axle, the wheel bearings are bolted to the wheel bearing housing. The wheel bearings on the front and rear axles are identical in construction. Wheel hub Wheel bearing housing Bolted connection Bolted connection S277_044 15 Measurement The particularities of measurement The Phaeton is equipped with 4-corner air suspension as standard. Before every measurement, the level position of each suspension strut must be checked. In addition, a toe-in value is set at the front axle when the suspension is extended. The adjustment must be made with the wheel extended by 60 mm when the vehicle is empty. When measuring the vehicle, the familiar parameters, camber and toe-in, must be adjusted on the rear or front axle. Adjusting the toe-in curve with the wheel in an extended state sets the toe-in curve for driving stability. Toe-in curve diagram Extension in mm -120. -100. -80. -60. -40. -20. 60. 40. -20. 20. -40. -60. Toe-in in degrees 20. 40. 60. 80. S277_042 16 100. Compression in mm The following steps are important when performing the front-end alignment: - Setting the basic toe-in with an empty vehicle by changing the length of the track rod - Setting the inclination of the toe-in curve by changing the height of the outer track rod joint S277_021 h A S277_020 h = Adjustment range for the toe-in curve A = Adjustment option for independent toe-in 17 Steering system The steering system Overview S277_093 The steering column The Phaeton is equipped with an adjustable steering column. The travel range is 50 mm in the axial direction and 40 mm in the vertical direction. The steering column is available with either manual or electric adjustment. S277_083 18 Adjustment of the steering column - mechanical adjustment Steering tube Disc pack S277_066 unclamped clamped With manual adjustment, eight steel discs lock the steering column in place on each side of the steering tube using a clamping mechanism. Here there are four discs for axial adjustment and four discs for vertical adjustment per side. The advantage: infinite adjustment with high holding forces. Adjustment of the steering column - electrical adjustment The electric steering column is essentially the same in concept as the manually adjustable steering column with reference to kinematics, adjustment field, installation space, connection and crash concept. Console The electric steering column is infinitely adjustable in the axial and vertical directions and is driven by electric motors. Pull tab Motor for axial adjustment Crash carriage Spindle for vertical adjustment S277_081 19 Steering system Adjustment of the steering column - circuit diagram The comfort CAN bus carries the command signal to adjust the steering column, and the control unit for driver seat/mirror position processes it. The steering column electronics control unit interprets and reads the driver's wish from the steering column adjustment button and places the signal on the comfort CAN bus. The control unit for driver seat/mirror position then sets the motors to the corresponding position. Hall sensors in the adjuster motors send the return signal to the control unit for driver seat/ mirror position. Switch for steering column adjustment ± Z, ± Y Control unit for steering column electronics J527 Steering column adjustment motor, Z Steering column Z position Control unit for driver seat/mirror position J543 Steering column Y position Steering column adjustment motor, Y S277_091 20 The electric steering column lock The Phaeton uses an electric steering column lock instead of a mechanical steering lock. The electric steering column lock is an integrated system with an electrical interface to the access and start authorisation control unit and a mechanical interface to the steering column. Locking collar unlock Locking star lock Push rod Worm gear S277_074 Motor for steering column lock, N360 Control unit with two Hall sensors Control unit for access and start authorisation, J518 When the electric motor is activated, the worm gear moves the push rod in the longitudinal direction. To lock the steering column (terminal 15, out), the inner-toothed locking collar is pushed over the conical, outer-toothed locking star until it stops. To unlock the steering column (terminal S, in), the locking collar is pulled away from the locking star. 21 Steering system The Servotronic Design and function The Phaeton is equipped with Servotronic. This hydraulic steering system, which is electronically controlled and speed dependent, is distinguished by light, comfortable steering while parking and a safe driving feel with increasing speed. Power-steering pump Servotronic solenoid valve, N119 S277_049 22 The Servotronic characteristic curve diagram Pressure p (bar) 120 100 0 km/h 80 50 km/h 60 120 km/h 40 20 0 10 8 6 4 2 0 2 4 6 8 10 S277_051 Application moment (Nm) The diagram shows how the pressure changes with respect to application moment in relation to driving speed. The characteristic curve has been specifically adjusted to the vehicle character. The Servotronic steering system is based on hydraulic steering. The hydraulic steering's modified rotary valve uses the principle of direct hydraulic reaction (feedback). Using an electro-hydraulic converter and reconfiguring the steering valve accordingly has enabled the Servotronic system to operate according to driving speed. 23 Steering system The electric control The Servotronic control unit evaluates the road speed signal from the dash panel insert and converts the signal into modulated current. This actuates the N119 solenoid valve. The N119 solenoid valve determines the hydraulic reaction at the rotary valve and thus the application moment at the steering wheel. The speed dependent influence on the steering translates into minimum forces required for steering at still stand and low speeds. Since the hydraulic reaction changes in relation to diving speed, the application force at the steering wheel increases with increasing speed. This gives the driver especially good contact with the roadway, allowing the driver to steer accurately. Road speed signal 15 31 Servotronic solenoid valve, N119 S277_095 24 Safety with the Servotronic system The steering system remains fully functional if the vehicle electrical system fails or other electrical faults occur. The Servotronic system then works using the mechanical forced opening of the N119 solenoid valve at maximum hydraulic reaction (fast speed characteristic curve). If the road speed signal fails while driving, the Servotronic system remains at the last given control range until the ignition is switched off. The next time the motor is started, the maximum hydraulic reaction develops, according to the fast speed characteristic curve. The characteristic curve for control current to the solenoid valve 900 Converter current I [mA] 800 700 600 500 400 300 200 100 0 Tacho frequency fe [Hz] 0 0 20 20 40 60 40 80 60 100 80 120 100 140 120 160 140 180 160 S277_067 Driving speed v [km/h] 25 Steering system The rotary valve in neutral position - vehicle stationary The familiar hydraulic pump generates the pressure that the Servotronic system requires, about 130 bar, which is transferred to the rotary valve. In the valve unit is a torsion bar, which is pinned to the rotary valve on one side and to the driving pinion and control bush on the other side. The torsion bar is responsible for centering (neutral position). Control unit Rotary valve Control bush Road speed signal Torsion bar Return Torsion bar from the pump Pin connection Reaction piston Solenoid valve for Servotronic Working cylinder, left Rotary valve Working cylinder, right S277_053 Working cylinder, left 26 Working cylinder, right Control bush Pressure and flow relief valve The oil that the hydraulic pump supplies flows through the connection hole in the valve region and into the inflow radial channel. It then flows into the cross holes in the control bush to the inflow control channels in the rotary valve. In the valve neutral position, the oil flows via the open inflow control vanes into all axial channels in the control bush. From there it flows via the open return control vanes also into the return control channels in the rotary valve. From these channels, the oil can flow through connections into the return chamber, and from there back to the oil reservoir. At the same time, the radial channels in the valve body and the associated tube lines connect the right and left working cylinder chambers. Return control channel Return control vane Inflow radial channel Inflow control channel Inflow control vane Axial channel S277_055 Radial channel Reaction piston Inflow radial channel Radial channel Reaction chamber Return chamber Right working cylinder Left working cylinder from the pump Return Control bush S277_057 27 Steering system The rotary valve in working position, left full steering lock - driving at low speed At left full steering lock, oil must flow to the right side of the working cylinder to assist the steering effort. The force at the steering wheel turns the torsion bar in its elastic range, since it is pinned to the rotary valve at the top and to the control bush and driving pinion at the bottom. The pressurised oil travels via the inflow control vanes, which are further open, into the associated axial channels, through the hole in the radial channel and via a tube line to the right cylinder chamber, thus hydraulically assisting the steering rack to move. The pressurised oil in the right cylinder chamber pushes the oil out of the left cylinder chamber into the return line. The torsion bar, which narrows in the appropriate region, turns the rotary valve against the control bush. If the driver releases the steering wheel, the torsion bar ensures that the rotary valve and the control bush spring back into the neutral position. Control unit Rotary valve Control bush Road speed signal Torsion bar Return Torsion bar from the pump Reaction piston Solenoid valve for Servotronic Working cylinder, left Pin connection Rotary valve Working cylinder, right S277_059 Working cylinder, left 28 Working cylinder, right Control bush Pressure and flow relief valve The servotronic control unit evaluates the road speed signal and passes it on to the N119 solenoid valve as modulated control current. Due to the maximum current produced in this driving situation, the N119 solenoid valve closes and prevents oil from flowing from the inflow radial channel to the reaction chamber. A baffle ensures that the return pressure level also acts in the reaction chamber. Thus, the Servotronic rotary valve behaves as a normal rotary valve in this situation. The steering is light and can be operated with little effort since the reaction has been eliminated. Baffle Radial channel Inflow radial channel Reaction piston Solenoid valve for Servotronic Radial channel Reaction chamber Return chamber Right working cylinder Left working cylinder Control bush from the pump Return S277_061 29 Steering system The rotary valve in working position, right full steering lock - driving at high speed At right full steering lock, oil must flow to the left side of the working cylinder to assist the steering effort. The force at the steering wheel turns the torsion bar in its elastic range, since it is pinned to the rotary valve at the top and to the control bush and driving pinion at the bottom. The torsion bar, which narrows in the appropriate region, turns the rotary valve against the control bush. The pressurised oil travels via the inflow control vanes, which are further open, into the associated axial channels, through the hole in the radial channel and via a tube line to the left cylinder chamber, thus hydraulically assisting the steering rack to move. The pressurised oil in the left cylinder chamber pushes the oil out of the right cylinder chamber into the return line. If the driver releases the steering wheel, the torsion bar ensures that the rotary valve and the control bush spring back into the neutral position. Rotary valve Control unit Control bush Road speed signal Torsion bar Return Torsion bar Pin connection from the pump Reaction piston Rotary valve Solenoid valve for Servotronic Working cylinder, left Working cylinder, right S277_063 Working cylinder, left 30 Working cylinder, right Control bush Pressure and flow relief valve As the speed increases, the Servotronic control unit reduces the control current to the N119 solenoid valve. With this, the N119 solenoid valve takes on a certain opening position and enables a limited oil inflow from the inflow radial channel into the reaction chamber. A baffle prevents large amounts of oil from flowing out into the return chamber, so that higher pressure develops in the reaction chamber. The increased pressure acting on the reaction piston then generates a greater pressing force on the balls guided by V-ways. These balls are located between the reaction piston and the centering piece, which is firmly joined to the control bush. Baffle During straight driving, this has a positive effect on the centering of the rotary valve, making it particularly exact. When the rotary valve pivots, the balls, which are now more highly loaded, exert additional resistance against turning of the rotary valve. Therefore, with the hydraulic reaction in this sequence of operations, the specifically determined application moment required to move the steering wheel is higher. Ball Reaction piston Inflow radial channel Reaction chamber Solenoid valve for Servotronic Centering piece Cut-off valve Return chamber Control bush S277_065 At high driving speeds, the N119 solenoid valve is completely open due to the very low or zero control current. Thus, the inflow radial channel supplies maximum pressure to the reaction system. When the driver turns the steering wheel to the right, the reaction pressure also increases corresponding to the prevailing operating pressure and pushes the reaction piston out of the reaction chamber. As soon as the reaction pressure, which is determined specifically for the vehicle, is reached, the cut-off valve opens and the oil flows out into the return chamber so that the pressure does not increase further. The application moment at the steering wheel now does not increase further, and conveys a secure driving feel through optimum contact with the roadway. 31 Brake system The brake system The Phaeton’s high performance brake system consists of newly developed front and rear wheel brakes. Foot parking brake Pedal cluster Dual brake servo ABS hydraulic unit Front wheel brake 32 The brake system is fitted with the Bosch ABS System 5.7 with integrated ESP as standard. It is diagonally separated into 2 circuits. The Phaeton has large ventilated brake discs front and rear. S277_006 Rear wheel brake Brake cables Brake lines 33 Brake system The brake equipment (all brake parts are made of aluminium) Engine Front Rear V6 Ø 323 mm x 30 mm Ø 280 mm x 22 mm V8 Ø 360 mm x 34 mm Ø 310 mm x 22 mm V10 TDI, W12 Ø 365 mm x 34 mm Ø 335 mm x 22 mm The wheel brakes To satisfy demanding safety requirements and guarantee a high level of comfort, the wheel brakes have been specially designed for the Phaeton. The front wheel brakes A new aluminium brake calliper was developed for the Phaeton's 18" front wheel brake. This lightweight brake calliper consists of an unseparated housing in a monoblock design with 8 pistons and 4 brake pads. This arrangement ensures optimum conditions for pressing the brake pads onto the brake disc. The brake calliper design, which has a wide reach around the friction ring, achieves a low weight combined with optimal calliper stiffness. S277_103 34 The front brake disc The front brake disc is constructed from two parts. The friction ring is attached to the brake disc cup with sliders. The design allows the brake disc to freely expand radially. This significantly improves the thermal shock resistance, that is, it increases the life of the brake disc. At the same time, this type of connection has a favourable effect on the deformation of the friction ring under temperature loading. Thus, the noise behaviour is also improved. A positive spin-off of this design is the weight saved by manufacturing the cup from aluminium. The specially formed cooling ribs provide a robust construction with optimal flow-through. Specially shaped rims and an air guide part guide the air stream directly to the brake disc. Brake disc cup made of aluminium S277_012 Slider Friction ring The rear wheel brakes The Phaeton's rear wheel brakes are highperformance, ventilated disc brakes. The brakes use a newly developed aluminium brake calliper. The parking brake feature is integrated into the brake calliper. S277_008 35 Brake system Actuation of the rear wheel brakes When the driver applies the hand brake, the brake cables actuate the parking brake lever on the brake calliper. The actuating shaft turns and performs a stroke. The mounting of the actuating shaft on three balls, which are positioned on a sloped disc, produces the stroke. The stroke movement actuates the piston which clamps the brake calliper and presses the brake pads against the brake disc. Automatic resetting To retain the mechanical and hydraulic function of the brakes in this system, the increase in clearance that results from brake pad wear must be compensated by resetting. A turning action of the resetting nut on the thread of the push bar resets the clearance increase that results from brake pad wear. Push bar Sloped disc Parking brake lever Actuating shaft Brake pad Housing Compression spring Resetting nut Spring washer Piston Brake disc S277_108 36 S277_110 Push bar Resetting nut Increased clearance When the driver applies the brakes and hydraulic pressure develops in the brake system and brake callipers, the piston moves in the housing towards the brake disc. The resetting nut is carried in the piston by a spring washer. If the clearance increases due to brake pad wear, it is compensated in the thread between the push bar and resetting nut. The force of the compression spring on the resetting nut acts against the pressing direction of the piston. This opens the cone clutch between the resetting nut and the piston (figures A and B). S277_112 Cone clutch S277_114 Nominal clearance The push bar is held by the compression spring; the turns of the thread between the push bar and resetting nut are engaged in this resetting sequence. The coarse-pitch thread between the push bar and resetting nut produces a turning moment on the resetting nut. The cone clutch between the resetting nut and the piston opens far enough so that the resetting nut can turn on the thread of the push bar by the amount of the increased clearance in the brake application direction. This resetting process takes places also when the brake calliper is relieved, that is, after the braking process. Thus the brake wear that occurs while braking is directly and non-incrementally reset. After the brake calliper is relieved, a clearance between the brake pads and brake disc appears (figure D). The nominal clearance is the play between the resetting nut and push bar thread determined by tolerances (figure C). S277_116 Clearance 37 Brake system The foot parking brake Release cable Release lever Pedal For the first time, Volkswagen has introduced in the Phaeton a foot parking brake, distinguished by its low weight, minimum release force and responsive design. The pedal cluster is manufactured from aluminium alloy. The parking brake is located in the left of the footwell above the foot rest. The parking brake is applied by pressing the pedal. 38 Control cable S277_109 When the driver presses the foot parking brake pedal, a control cable transfers the applied force to a lever mechanism under the floor of the vehicle. Here, the force is divided over two brake cables, which operate the actuating mechanisms on the rear wheel brakes. The parking brake is released by pulling the release lever below the light rotary switch by hand. Drum Release cable Coil spring Coil spring Cable retainer Drum Plastic spring Retainer for release cable Control cable S277_156 Pedal The coil spring, which acts on a drum, takes on the brake locking function. The spring slides on the drum and expands due to the direction of movement. If the counter force of the brake moves the spring in the other direction, it pulls together and increases the friction between the coil spring and drum. Thus, the pedal locking action is almost completely stepless and noiseless. An additional plastic spring produces the typical click sound when the pedal is pressed. When the driver pulls the release lever, the retainer of the release cable is drawn upwards. This expands the coil spring, or in other words, the spring becomes moveable and the pedal can return to the initial position. This principle requires low release forces. Expand S277_152 Lock: The coil spring presses against the drum when the pedal moves in the opposing direction. S277_154 Release: The diameter of the coil spring becomes larger when the spring expands. The coil spring can move on the drum. 39 Brake system The brake lines and brake cables The brake line system connects the hydraulic components of the brake system. The brake lines consist of galvanised steel pipes, which have a resistant surface protection provided by the zinc plating and an additional polyamide coating. These lines are attached to the body with plastic holders. A robust, hard outer shell is used for attachment. Injected, soft elements are used for noise insulation. The moveable connections in the lines to the front and rear axles are brake tubes. The inner tube consists of a material that keeps water absorption into the brake fluid low. For stabilisation, this tube has several braided fibre sleeves, which are protected against external influences by CR rubber. The lines in the engine compartment as well as those in the connection lines between the ESP unit and the brake servo are connected to plastic tubes with braided steel sheathing. The structure of these lines also reduces noise transfer from the unit during operation. The hand brake cable Structure of the hand brake cable Profile wire spiral made of bare drawn stranding wire Polyamide Protective shell made of polyurethane Lining tube made of Polyamide Wire strand made of drawn stranding wires The brake cables are sheathed in polyamide and greased to prevent corrosion and reduce friction forces. 40 S277_102 The pedal cluster The bearing block of the pedal cluster is made of aluminium alloy. It is designed to break at a specific location in the event of a crash. Thus the driver's lower legs and feet are not endangered. To upgrade the aesthetics, additional custom covers are fitted to the pedals. Pedal cluster - manual transmission Pedal cluster - automatic transmission S277_119 S277_117 41 Brake system The Bosch 5.7 ABS / ESP anti-lock braking system The Phaeton uses the Bosch 5.7 ABS system with ESP (electronic stability program) with hydraulic braking assistant. S277_131 42 The special characteristics of the Bosch 5.7 ABS system include: - The hydraulic unit and control unit are integrated into one unit. The G201 brake pressure sensor screws directly into the hydraulic unit. An ESP feature without preloading is provided. The ESP has EDL, TCS and ABS features as well as a braking assistant. Even when the active ESP function is switched off, the vehicle remains stable in critical situations due to the application of ESP logic (“passive” ESP). Control unit with hydraulic unit S277_106 G201 Brake pressure sensor S277_104 43 Brake system The active wheel sensor system The speed sensor is made of a material that changes its electrical conductivity depending on a magnetic field. An electronic switch converts the current fluctuations induced in the sensor material into voltage fluctuations at the sensor output. If the signal wheel moves relative to the sensor, the sensor generates a square-wave voltage signal at the corresponding frequency depending on the speed of rotation. The advantage compared to previously used systems is that it is possible to exactly detect the speed of wheel rotation right down to zero rotation. Speed sensor S277_160 Sensor housing Sensor electronics Signal wheel S277_158 For more information on the active wheel sensor system, please see SSP 218 “The Lupo 3L TDI”. 44 The dual brake servo Pressure sensor, only in vehicles with ADC Displacement sensor, only in vehicles with ADC Connection for release switch, only in vehicles with ADC S277_105 The brake servo is an 8/9" dual brake servo with a stroke of 36 mm. The diameter of the main brake cylinder is 26.99 mm. The dual brake servo has a light-weight construction and has the following features: - The central valves of the dual main brake cylinder guarantee the shortest application distance at the pedal combined with reliable, self-priming ESP functionality. - The active (electrically activated) brake servo variant represents the core component for activation with automatic delay of the vehicle in ADC operation (automatic distance control) and guarantees regulated, automatic delay. Vehicles with ADC have an active brake servo. For more information, please see SSP 276 “Automatic distance control”. 45 Wheels and tyres The wheels and tyres The Phaeton sets standards in comfort and driving dynamics. Different wheel-tyre combinations are available with the Phaeton. Vehicles with V6 petrol engines are equipped with cast aluminium wheels with dimensions 7½ J 16 ET40 and 235/60R16 tyres as standard. S277_045 Vehicles with W12 petrol engines have 18" cast aluminium wheels with dimensions 7½ J 18 ET40 and 235/50R18 tyres. S277_043 One-piece cast aluminium hollow spoke wheels are also optional for all engine types. The 8½ J 18 ET45 wheel comes with a 255/45R18 tyre. S277_041 46 S277_162 All normal tyres have the “Y” speed index (300 km/h) and the special designation “XL”. (XL = EL = extra load = reinforced) The puncture repair kit Emergency tyre inflation The Phaeton is equipped with puncture repair kit as standard. A complete spare wheel with tyre can be ordered instead of the puncture kit. The chapter “Tips and Maintenance” in the operating manual describes how to use the breakdown set. S277_039 47 Tyre pressure monitor Tyre pressure monitor (TPM) Combi-processor in dash panel insert Function selector switch in Infotainment Receiving antenna S277_121 Tyre valves with wheel electronics Control unit for monitoring tyre pressure Function of the tyre pressure monitor The tyre pressure monitor continuously monitors the tyre pressure while driving and also when the vehicle is stationary. The tyre pressure monitor used in the Phaeton is a 5-wheel system. The spare wheel is also monitored and included in the system messages. 48 A measuring and transmitting unit mounted in each tyre valve sends radio signals at regular intervals to the antennas mounted in each wheel housing. The signals are then passed on to the control unit for monitoring the tyre pressure. The control unit evaluates the tyre pressures or changes in tyre pressure and sends corresponding system messages to the dash panel insert. The system messages then appear on the driver information system display. If the driver has selected the “Vehicle” menu in the main information display and operating unit (ZAB), the system messages for tyre pressure monitor are displayed. The system recognises the following situations: - Gradual pressure loss: The system informs the driver in time to be able to correct the tyre pressure. - Sudden pressure loss: The system warns the driver immediately while driving. - Excessive pressure loss when the vehicle is stationary: The system warns the driver immediately after the ignition is switched on. 49 Tyre pressure monitor The tyre pressure sensors G222...G226 The tyre pressure sensors are screwed to the metal valves and can be reused when the wheels or rims are changed. The following components are integrated into a tyre pressure sensor: Tyre pressure sensor Transmitting antenna Pressure and temperature sensor Measuring and control electronics Metal valve Battery S277_358 The pressure sensor detects the actual tyre inflation pressure (absolute pressure measurement). The pressure is then sent to the tyre pressure monitoring control unit for evaluation. The temperature signal is used for compensating temperature-dependent pressure changes in the tyres as well as for diagnostic purposes. The control unit for monitoring the tyre pressure performs the temperature compensation. The measured tyre inflation pressures are normalised to a temperature of 20 °C. 50 S277_118 The pressure sensor, temperature sensor and measuring and control electronics are integrated into one intelligent sensor. When the driver selects “Store pressures”, the tyre inflation pressures are normalised to 20 °C. To avoid making incorrect settings, pay particular attention that the tyre inflation pressures are checked or corrected and stored with “cold tyres”. The following information is sent from the transmitting antenna of the tyre pressure sensor: - Individual identification number (ID code), - Current tyre inflation pressure (absolute pressure), S277_120 - Current tyre air temperature, - Condition of the integrated battery and - The status, synchronisation and control information necessary for secure data transfer. The ID codes Each tyre pressure sensor has an individual identification number (ID code), which is used for “own wheel recognition”. S277_122 0000755100 0000678500 0000675300 0000735700 0000597400 S277_121 51 Tyre pressure monitor The tyre pressure monitoring antennas R59 ... R62 The antennas for monitoring the tyre pressure, R59 ... R62, are located in the wheel housings behind the wheel arch shells. S277_120 S277_123 The antennas for monitoring the tyre pressure receive radio signals from the tyre pressure sensors and transfer these signals to the control unit for monitoring the tyre pressure for further processing. The tyre pressure monitor has 4 antennas for monitoring tyre pressures. They are mounted in the FL, FR, RL, RR wheel housings behind the wheel arch shells. The antennas receive all radio signals transmitted in their reception and frequency range. Each antenna receives the radio signals of all wheel sensors that are in range. The control unit filters and selects the radio signals so that it can process the correct information. They are connected to the control unit for monitoring the tyre pressure using high frequency antenna lines and are allocated to the control unit according to their location. The spare wheel does not have a separate antenna assigned to it. The antennas receive the radio signals that the spare wheel transmits (data messages) and transfer the signals to the control unit for monitoring the tyre pressure. The control unit recognises and stores the “fifth wheel” as the spare wheel using own wheel and position recognition. 52 The system overview S277_124 The components G222 Front left tyre pressure sensor R60 Tyre pressure monitoring antenna, R61 Tyre pressure monitoring antenna, front right G223 Front right tyre pressure sensor G224 Rear left tyre pressure sensor rear left G225 Rear right tyre pressure sensor G226 Spare wheel tyre pressure sensor J218 Combi-processor in dash panel insert R62 Tyre pressure monitoring antenna, rear right J502 Control unit for monitoring the tyre pressure J523 Main information display and operating unit = Input signal R59 Tyre pressure monitoring antenna, = Output signal front left = Positive = Ground = CAN data bus = Gold contact 53 Tyre pressure monitor The warnings The strong warnings Pressure/bar Sudden pressure loss Flat tyre! S277_128 Time/s S277_130 The wheel electronics sends data messages every 54 seconds. If the wheel electronics detects a sudden change in pressure (>0.2 bar/min.), it transmits in 850 ms cycles. 54 Target tyre pressure stored via the menu. The system calculates the target pressures relative to 20 °C from the respective inflation pressures. Strong warning due to sudden pressure loss >0.4 bar below the stored target tyre pressure. The pressure falls below the coded minimum pressure of, for example, 1.9 bar for W12. Dynamic strong warning on sudden pressure loss >0.2 bar relative to the last transmitted pressure value. The soft warnings Check pressures! Pressure/bar Slow pressure loss S277_140 Time/s S277_142 The wheel electronics sends data messages every 54 seconds. If the wheel electronics detects a sudden change in pressure (>0.2 bar/min.), it transmits in 850 ms cycles. Soft warning due to pressure loss between 0.2 and 0.4 bar below the stored target tyre pressure. If the driver has inflated the tyres to pressures critical to driving dynamics, the system also issues warnings. - The difference in target pressures on one axle may not exceed 0.4 bar. - The difference in target pressures between the axles may not exceed 0.5 bar. If the spare tyre pressure falls below its stored target pressure by more than 0.4 bar, a soft warning likewise appears. Strong warning due to pressure loss >0.4 bar below the stored target tyre pressure. 55 Tyre pressure monitor The warnings in the dash panel insert (centre display) The small symbol is always displayed. The large symbol only appears when the “Tyre pressure monitor” menu is open. It disappears when another menu opens. ... Display during the learn phase System is learning! S277_146 ... Display when switching off System switched off! S277_146 ... Display during radio fault Warning currently not possible! S277_146 ... Display during system fault System fault! S277_148 ... Display when faulty wheel on board Faulty wheel on board! S277_148 56 The controls “Vehicle” function key S277_150 TPM Vehicle Spare wheel monitoring Inflation information Target pressures in [bar] at 2° C Adopt current pressures Tyre pressure monitor main menu with strong warning rear right S277_127 The driver is responsible for correctly setting the tyre pressures to be monitored. 57 Tyre pressure monitor The tyre pressure monitor system main menu appears in the main information display and operating unit (ZAB) display when the “Vehicle” function key is pressed. After pressing the “Adopt current tyre pressures” function key and then confirming the pressures, the system stores the current tyre inflation pressures at the current tyre inner temperatures for the respective IDs. The following functions are stored - Switch on/off tyre pressure monitor system Switch on/off spare wheel monitoring Inflation info Adopt current pressures The driver can specify and set the tyre pressures to be monitored within the limits coded according to the vehicle series. 58 Pressing the key also starts a new learn process for wheel assignment. To avoid receiving from external wheel electronics while learning, the system learns only when travelling faster than 5 km/h. The learning process is complete after about 15 minutes driving time. Check Your Knowledge 1. What is special about the Phaeton's wheel bearings? a. They are bolted to the wheel bearing housing as one unit. b. They are joined to the wheel bearing housing by optimal pressing. c. They can be installed without removing the pivot bearing or jointed shaft. 2. Which components have advantageous effects on the scrub radius and the road feedback lever arm? a. The light-weight brake calliper, which consists of an unseparated housing in a monoblock design with 8 pistons and 4 brake pads. b. The electronically controlled and speed dependent Servotronic system. c. The virtual steering axis. 3. Where is the antenna that receives the data messages from the tyre pressure sensor in the spare wheel? a. In the boot. b. In the centre console between the driver and front passenger. c. The spare wheel does not have its own antenna; the other antennas receive the signals from the spare wheel sensor and identify the sensor using its unmistakable ID code. 59 1.: a, c; 2.: c; 3.: c; 277 Only for internal use © VOLKSWAGEN AG, Wolfsburg All rights reserved 240.2810.96.20 Issued 03/02 ❀ No chlorine was used to bleach this paper during manufacture.
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