Modules - europeantransmissions.com · 9 Modules SSP 228/040 Housing, Screws, Bolts Hydraulic...

7

Modules

Damper

The Flywheel

and Damper Assembly

In reciprocating engines, the unevennessof the combustion sequence inducestorsional vibration in the crankshaft.

This torsional vibration is transmittedto the transmission and results inresonant vibration, producing noise andoverloading components inthe transmission.

The flywheel and damper assemblyand the dual-mass flywheel dampentorsional vibration and ensure theengine runs quietly.

In the 3.0-liter V6 engine, engine torque istransmitted to the transmission through aflywheel and damper assembly.

Because four-cylinder engines do notrun as smoothly as six-cylinder engines,a dual-mass flywheel is used infour-cylinder engines.

SSP 228/004

Dual-MassFlywheel

SSP 228/032

Flywheel

8

Modules

Sectional View of Transmission

For better representation,the oil pump and the transfercase are shown folded on thecutting plane.

9

Modules

SSP 228/040

Housing, Screws, Bolts

Hydraulic Parts/Control

Electronic Transmission Control

Shafts, Gears

Plate Clutches

Pistons, Torque Sensors

Bearings, Washers, Circlips

Plastics, Seals, Rubber

Color Definitions

10

Modules

The Forward Clutch/Reverse

Clutch with Planet Gear Set

In contrast to multi-step automatictransmissions, such as the 01V, which usea torque converter, separate clutches areused for forward and reverse travel in theAudi CVT design. These “wet plateclutches” are also used to executegearshifts in multi-step automatictransmissions. They are used for drivingoff and transmitting the torque to theauxiliary reduction gear step. The drive-offprocess and torque transmission aremonitored electronically and regulatedelectro-hydraulically.

The electro-hydraulically controlled wetplate clutch has the following advantagesover a torque converter:

• Low weight

• Very little installation space is required

• Adaptation of clutch engagementcharacteristic to driving situation

• Adaptation of slip torque todriving situation

• Protective function in the event ofoverloading or misuse

SSP 228/005

Reverse Clutch

ForwardClutch

Planet Carrier

Input Pulley Set 1(Auxiliary Reduction Gear Step)

Forward Clutch/Reverse Clutchwith Planetary Gear Train

Planetary GearsTransmissionInput Shaft

Ring Gear

11

Modules

The Planetary Gear Train

The planetary gear train is constructed as aplanet reversing gear set and its onlyfunction is to change the rotational directionof the transmission for backing up.

The reduction ratio in the planetary geartrain is 1:1 when backing up.

Assignment of Components

The sun gear (input) is linked to thetransmission input shaft and the steelplates on the forward clutch.

The planet carrier (output) is linked to thedrive gear, the auxiliary reduction gear step,and the lined plates on the forward clutch.

The ring gear is connected to theplanetary gears and the lined plates on thereverse clutch.

SSP 228/008

Steel Plates and Lined Plateson Forward Clutch

Ring GearSteel Plates and Lined Plateson Reverse Clutch

Sun Gear Input Pulley Set 1(Auxiliary ReductionGear Step)

Planet Carrier withPlanetary Gears

TransmissionInput Shaft

12

Modules

Power Flow in the Planetay Gear Train

Torque is transferred to the planetary geartrain via the sun gear which is connected tothe input shaft and drives the planetarygears 1.

Planetary gears 1 drive planetary gears 2,which are in mesh with the ring gear.

Planet Carrier

The planet carrier (output planetary geartrain) is stationary because it acts as theinput for the auxiliary reduction gear stepand the vehicle is still not moving.

The ring gear idles and rotates athalf engine speed in the direction ofengine rotation.

SSP 228/033

Direction of Rotation of Components when

Engine is Running and Vehicle is Stationary

Transmission Input Shaftwith Sun Gear

Ring Gear

Planetary Gear 2Planetary Gear 1

13

Modules

Power Flow During Forward Travel

The steel plates on the forward clutch arelinked to the sun gear and the lined platesare linked to the planet carrier.

SSP 228/009

When the forward clutch is engaged, itconnects the transmission input shaft tothe planet carrier (output). The planetarygear train is locked and rotates in the samedirection as the engine; the torquetransmission ratio is 1:1.

Oil Pressure for ClutchTorque Flow

Forward Clutch

Planetary Gear Train

14

Modules

Power Flow in Reverse

The lined plates of the reverse clutchare connected to the ring gear and thesteel plates are connected to thetransmission housing.

When the reverse clutch engages, it holdsthe ring gear and thereby prevents thetransmission housing from rotating.

SSP 228/010

Reverse Clutch

Torque is then transmitted to the planetcarrier, which begins to rotate in theopposite direction to the engine. Thevehicle moves in reverse.

Road speed is limitedelectronically when thevehicle is in reverse.

The Variator remains in thestarting torque ratio.

Oil Pressure for ClutchTorque Flow

Ring Gear

15

Modules

Accelerator Pedal AngleEngine SpeedNominal Engine SpeedTransmission Input Speed, Pulley Set 1Transmission Output Speed, Pulley Set 2

20

40

60

80

100

1000

01 2 3 4 5 6 7 8 9 10

2000

3000

4000

0

Accelerator Pedal100% Depressed

Eng

ine

Spe

ed

Time in Seconds SSP 228/052

20

40

60

80

100

1000

01 2 3 4 5 6 7 8 9 10

2000

3000

4000

0

Eng

ine

Spe

ed


AcceleratorPedal 60%Depressed

20

40

60

80

100

1000

01 2 3 4 5 6 7 8 9 10

2000

3000

4000

5000

6000

0

Eng

ine

Spe

ed


Accelerator Pedal100% Depressed+ Kickdown

The Clutch Control

Clutch Engagement

Engine speed controls CVT clutchengagement to initiate vehicle motion.

The accelerator pedal angle and applicationspeed set by the driver and the control maprequirements of the Transmission ControlModule J217 determine the clutchengagement characteristics for eachvehicle start from rest.

Depending upon the specific driver inputsfor each start, the Transmission ControlModule J217 sets a nominal engine speedat which clutch engagement will take place.

With the vehicle at rest, moderateapplication of the accelerator pedal(characterized by slow movement to asmall accelerator pedal angle) initiates thetransition from engine idling speed toclutch engagement speed at a relativelylow engine speed. Short clutch slip timesand low engine speed at clutchengagement will provide the best fueleconomy.

For a performance start from rest, heavyapplication of the accelerator pedal (quickmovement to a large accelerator pedalangle) initiates the transition from engineidling speed to clutch engagement enginespeed at a higher engine rpm. The greatertorque developed at higher engine rpmyields faster vehicle acceleration.

Differences in engine type andperformance characteristics also have aneffect on CVT clutch engagementcharacteristics.

16

Modules

Electronic Control

The following parameters are used forclutch control:• Engine speed• Transmission input speed• Accelerator pedal position• Engine torque• Brake applied• Transmission oil temperatureThe Transmission Control Module J217calculates the nominal clutch pressurefrom these parameters and determinesthe control current for Pressure ControlValve -1- for Automatic Transmission N215.The clutch pressure, and thereforethe engine torque to be transmitted by theclutch, changes almost in proportion tothe control current (refer to “HydraulicControl,” page 17).Automatic Transmission Sender -1- forHydraulic Pressure G193 registers theclutch pressure (actual clutch pressure) inthe hydraulic control. Actual clutch pressureis continuously compared to the nominalclutch pressure calculated by theTransmission Control Module J217.The actual pressure and specified pressureare checked continuously for plausibilityand corrective action is taken if these twovalues deviate from one another by morethan a certain amount (refer to “SafetyShut-Off,” page 18).To prevent overheating, the clutch iscooled and clutch temperature is monitoredby the Transmission Control Module J217(for more detailed information, refer to“The Clutch Cooling System,” page 23, and“Overload Protection,” page 18).

SSP 228/075

Transmission ControlModule J217

Automatic Transmission Sender-1- for Hydraulic Pressure G193

Pressure Control Valve -1- forAutomatic Transmission N215

17

Modules

Hydraulic Control

Clutch pressure is proportional to enginetorque and is not dependent on thesystem pressure.A constant pressure of approximately73 psi (500 kPa) is applied by the pilotpressure valve to the Pressure ControlValve -1- for Automatic Transmission N215.Pressure Control Valve -1- for AutomaticTransmission N215 produces a controlpressure which controls the position of theclutch control valve depending on thecontrol current calculated by theTransmission Control Module J217.A high control current results in a high

control pressure.

The clutch control valve controls the clutchpressure and therefore also regulates theengine torque to be transmitted.

The clutch control valve is suppliedwith system pressure and produces clutchpressure in accordance with the activationsignal from Pressure Control Valve -1- forAutomatic Transmission N215.A high control pressure results in a high

clutch pressure.

The clutch pressure flows via the safetyvalve to the manual selector valve.The manual selector valve transfers clutchpressure either to the forward clutch(position D) or to the reverse clutch(position R), depending on the selectorlever position. The non-pressurizedclutch is vented into the oil sump.In selector lever positions N and P, thesupply is shut off via the manual selectorvalve and both clutches are vented intothe oil sump.

ReverseClutch

ManualSelectorValve

ForwardClutch

SafetyValve

Pressure ControlValve -1- for AutomaticTransmission N215

PilotPressureValve

ClutchControlValve

P R N D

SSP 228/011

ATF Depressurized

Clutch PressureSupply Pressure

Pilot Control PressureControl Pressure

In the Oil Sump

18

Modules

Safety Shut-Off

A safety-critical malfunction has occurredif actual clutch pressure is clearly higherthan specified clutch pressure. In this case,the clutch is depressurized regardless ofthe manual selector valve position andother system states.

A safety shut-off is implemented viathe safety valve and enables the clutchto open quickly.

The safety valve is activated by SolenoidValve 1 N88. At control pressures aboveapproximately 58 psi (400 kPa), the supplyto the clutch control valve is shut off andthe connection to the manual selectorvalve in the oil sump is vented.

Overload Protection

Using a model calculation, the TransmissionControl Module J217 calculates the clutchtemperature from clutch slip, engine torqueto be transmitted, and transmission oiltemperature. Engine torque is reduced ifthe measured clutch temperature exceedsa defined threshold because of excessload on the clutch.

Engine torque can be reduced to the upperend of the idling speed range. It is possiblethat the engine will not respond to theaccelerator pedal for a short period of time.The clutch cooling system ensures a shortcooling-down time. Maximum enginetorque is quickly available again. Overloadof the clutch is almost impossible.

SSP 228/082

Switched Position After Safety Shut-Off

Vented into Oil Sump/Depressurized

Clutch Pressure

Supply Pressure

Pilot Control Pressure

Control pressure

In the Oil Sump

ForwardClutch

ManualSelectorValve

SafetyValve

ClutchControlValve

SolenoidValve 1N88

P RN D

ReverseClutch

19

Modules

Clutch Control when Vehicle

Is Stationary (Slip Control)

The slip control function sets the clutch to adefined slip torque (clutch torque) when theengine is running at idling speed and a driveposition is selected. The vehicle behaves inthe same way as an automatic transmissionwith a torque converter.

Selective clutch pressure adaptation resultsin an input torque which causes the vehicleto ”creep.”

Input torque is varied within defined limitsdepending on vehicle operating state andvehicle road speed. The contact pressureapplied by the taper pulleys is sensed byAutomatic Transmission Sender -2- forHydraulic Pressure G194. This informationis used for precision clutch torque control.

BrakePedal NotPressed

Because contact pressure is proportional tothe actual engine input torque presentat pulley set 1, clutch torque can beprecisely calculated and controlled usingAutomatic Transmission Sender -1- forHydraulic Pressure G193 (for more detailedinformation, refer to “The Torque Sensor,”page 33).

Slip control allows the vehicle tobe maneuvered when parkingwithout pressing the acceleratorpedal and therefore enhancesdriving comfort.

SSP 228/013

Automatic TransmissionSender -1- forHydraulic Pressure G193

29.5 psi(40 Nm)


20

Modules

Special Feature of the Slip Control

A special feature of the slip control isthe reduction of slip torque when thevehicle is stationary and the brakes areactuated. As a result, the engine is notrequired to develop so much torque (theclutch is also open wider).

This has a positive effect on fuel economy.Noise from the engine running at idlespeed when the vehicle is stationary isreduced and much less pressure has tobe applied to the brake pedal to stopthe vehicle.

SSP 228/012

11.1 psi(15 Nm)

If the vehicle rolls back when standingon a slope with only light pressureapplied to the brake, the clutch pressureis increased to immobilize the vehicle (“hill-holder” function).

By using two transmission output speedsenders (Sender for Transmission OutputRPM G195 and Sender -2- for TransmissionOutput RPM G196) it is possible todistinguish between forward travel andreverse travel, which makes the hill-holderfunction possible (for further information,please refer to “Sensors,” page 63).

BrakePedalPressed



0 (0)

37 (50)

74 (100)

111 (150)

148 (200)

184 (250)

221 (300)

10000 2000 3000 4000 5000 6000 7000

Eng

ine

Torq

ue in

lbs-

ft (N

m)

21

Modules

The Micro-Slip Control

The micro-slip control serves to adapt theclutch control (see description of adaptationprocess, page 22) and dampen the torsionalvibration induced by the engine.

In the part-throttle range, the clutchcharacteristics are adapted up to an enginetorque of 118 lbs-ft (160 Nm).

In the engine speed range up toapproximately 1800 rpm and at enginetorques up to approximately 162 lbs-ft(220 Nm), the clutch operates in what isknown as “micro-slip” mode. In thisoperating mode, a slip speed (speeddifferential) of approximately 5 rpm to 20rpm is maintained between thetransmission input shaft and pulley set 1.

SSP 228/092

For this purpose, the Transmission ControlModule J217 compares the signalgenerated by Sensor for Transmission RPMG182 with the engine speed, makingallowance for the auxiliary reduction gearstep. Sensor for Transmission RPM G182registers the rotation of pulley set 1.

As the term “micro-slip”suggests, clutch slip is kept ata minimum so no noticeablepenalties in lining wear and fueleconomy occur.

Engine Speed in RPM

Approximately1800 RPM

Clutch Closed

Micro-Slip Control Range

Adaptation Range During Micro-Slip Control:Up to Approximately 118 lbs-ft (160 Nm)

22

Modules

Clutch Control Adaptation

To be able to control the clutch comfortablyin any operating state and throughout itsservice life, the relationship betweencontrol current and clutch torque has to beupdated continuously.

This is necessary because thecoefficients of friction of the clutchesare constantly changing.

The coefficient of friction is dependent onthe following factors:

• Transmission oil (quality, aging, wear)

• Transmission oil temperature

• Clutch temperature

• Clutch slip

To compensate for these influences andoptimize clutch control, the relationshipsbetween control current and clutch torqueare adapted in slip control mode and in thepart-throttle range.

Adaptation in Slip Control Mode

(Brake Pressed):

As mentioned already, a defined clutchtorque is set in slip control mode.The Transmission Control Module J217observes the relationship between thecontrol current from Pressure Control Valve-1- for Automatic Transmission N215 andthe data from Automatic TransmissionSender -2- for Hydraulic Pressure G194(contact pressure) and stores these data.The actual data are used for calculatingnew characteristics.

Here, “adaptation” meanslearning new pilot control values.

Adaptation in Part-Throttle Range

In the part-throttle range, adaptation isperformed in micro-slip control mode.In this operating mode the TransmissionControl Module J217 compares the enginetorque from the Motronic Engine ControlModule J220 to the control current fromPressure Control Valve -1- for AutomaticTransmission N215 and stores these data.The actual data are used for calculatingnew characteristics (see “Micro-SlipControl,” page 21).

Summary:

The adaptation function serves to maintaina constant clutch control quality.

The adaptation data also have an effecton the calculation of clutch pressure athigher transmission torques (clutch fullypositively engaged).

High clutch pressures are not required,which ultimately has a positive effecton efficiency.

23

Modules

The Clutch Cooling System

The clutches are cooled by a separateoil flow in order to protect them fromexposure to excessively high temperatures(particularly when driving away underhard acceleration).

To minimize power losses due to clutchcooling, the cooling oil flow is directedwhere it is needed by a cooling oil controlmodule integrated into the valve body.

Additional cooling oil is supplied by asuction jet pump (entrainment pump)without placing a demand on oil

Forward Clutch

SSP 228/064

pump capacity.

To optimize clutch cooling, the cooling oilflows only to the power-transmitting clutchpulley set.

The cooling oil and the pressurized oil ofthe forward clutch flow through the hollowtransmission input shaft. The two oilcircuits are separated from one another bya steel tube, the “inner part.”

An “oil divider” located at the oil outletbores on the transmission input shaftguides the cooling oil flow to the forwardclutch and the reverse clutch.

Oil Divider withDiaphragm Spring andStop Ring with Openings

Diaphragm SpringDistributor Disc

Inner Part

Stop Ring

Oil Divider

Reverse Clutch

24

Modules

Cooling the Forward Clutch

If the forward clutch is engaged, thecylinder (thrust plate) of the forward clutchpresses the oil divider back.

In this position, the cooling oil flows pastthe front face of the oil divider and throughthe forward clutch.

Cooling the Reverse Clutch

If the forward clutch is not operated(when the engine is running at idling speedor when the reverse clutch is operated),the oil divider is in its basic position.

In this position, the cooling oil flows to theoil divider and is rerouted to the reverseclutch by a distributor plate. Branches in thedistributor pulley duct cooling oil to theplanetary gear train and provide thenecessary lubrication there.

SSP 228/014

Forward Clutch Reverse Clutch

Cylinder

Oil Pressure for Clutch

Clutch Cooling Oil Flow

25

Modules

Hydraulic Clutch Cooling Control

The clutch cooling system cuts inat the same time as the clutch controlis activated.

The Transmission Control Module J217applies a defined control current toSolenoid Valve 1 N88. This produces acontrol pressure which switches the clutchcooling valve.

SSP 228/045

The clutch cooling valve transfers pressurefrom the cooler return pipe to the suctionjet pump (entrainment pump).

The pressurized oil is used to operate thesuction jet pump (entrainment pump) (forfurther details, refer to “The Suction JetPump (Entrainment Pump),” page 46).


Control Pressure

In the Oil Sump

To Manual Selector Valve

To Cooler Return Pipe

SafetyValve

SolenoidValve 1N88

Pressure ControlValve -1- for AutomaticTransmsiion N215

ClutchCoolingValve

PilotPressureValve

Suction Jet Pump(Entrainment Pump)with Check Valve

To theClutches

ATF Depressurized

Cooling Oil Flow

Oil from Cooler Return Pipe

26

Modules

The Auxiliary Reduction Gear Step

Due to constraints on space, torque istransmitted to the Variator through anauxiliary reduction gear step.

SSP 228/017

The auxiliary reduction gear step hasdifferent reduction ratios to accommodatedifferent engines to the transmission. As aresult, the Variator is operated within itsoptimum torque range.

PlanetaryGear Train

Pulley Set 1

Auxiliary ReductionGear Step

27

Modules

The Variator

The basic operating principle of theVariator has been explained on page 3. Thespecial features and functions of themultitronic® Variator are described on thefollowing pages.

The Concept of the Variator Used in the

multitronic®

The operation of the Variator is based onwhat is known as the dual-piston principle.A special feature of the multitronic®Variator is the torque sensor integrated inpulley set 1 (for more detailed informationrefer to “The Torque Sensor,” page 33).

Pulley sets 1 and 2 each have a separatepressure cylinder for pressing the taperpulleys as well as a separate variabledisplacement cylinder for transmissionratio adjustment.

The dual-piston principle makes it possibleto change the transmission ratio veryquickly by applying a small amount ofpressure. This ensures that the taperpulleys maintain sufficient contact pressureat a relatively low oil pressure level.

SSP 228/018

Starting Torque Ratio

Pulley Set 2

Pulley Set 1

ChainTorque Sensor

28

Modules

Adjustment

A suitable supply of pressurized oil isrequired due to the heavy demands on theadjustment dynamics. To minimize therequired quantity of oil, the variabledisplacement cylinders have a smallersurface area than the pressure cylinders.Therefore, the quantity of oil needed foradjustment is relatively small.

This makes high adjustment dynamics andhigher efficiency possible despite the lowdelivery rate of the oil pump.

The diaphragm springs in pulley set 1and the coil springs in pulley set 2 createa defined basic chain tension (contactpressure) when the hydraulic systemis depressurized.

In the depressurized state, the Variatorfor the starting torque ratio is adjusted bythe spring force of the coil springs inpulley set 2.

SSP 228/019

End Torque Multiplication Ratio (Overdrive)

Pressure Cylinder Diaphragm Spring

Torque Sensor Variable Taper Pulley

Pulley Set 1

VariableDisplacementCylinder

Pulley Set 2

Variable Taper PulleyPressure Cylinder

Pressure Spring

VariableDisplacementCylinder

29

Modules

Contact Pressure

High contact pressures are requiredbetween the taper pulley and the chain totransmit the torque the engine develops.The contact pressure is produced byadjusting the oil pressure in the pressurecylinder as appropriate.

According to the principles of hydraulics, aresultant force (contact pressure) can bevaried as a function of pressure andeffective area.

The pressure cylinders have a largersurface area and can therefore apply therequired contact pressure with less oilpressure. The relatively low oil pressure isalso more efficient.

Towing

When the vehicle is being towed, pulley set2 drives pulley set 1 and there is a dynamicpressure buildup in the variabledisplacement cylinder and pressure cylinderof the pulley sets.

The system is designed in such a waythat the reduction ratio is adjusted toapproximately 1:1 by the dynamic pressurebuild-up in the Variator. Pulley set 1 andthe planetary gear train are thus protectedfrom excessively high engine speeds.

The diaphragm springs in pulley set 1 assistwith this process.

For more detailed informationregarding dynamic pressurebuild-up, refer to “The SplashOil Cover,” page 38.

Also observe the towinginformation given in “Towing,”page 91.

SSP 228/081

DiaphragmSpring inPulley Set 1

SSP 228/080

Resultant Force1124 lbs (5 000 N)

Effective Area15.50 in2

(100 cm2)

Pressure72.5 psi(500 kPa)

Resultant Force1124 lbs (5 000 N)

Effective Area7.75 in2 (50 cm2)

Pressure 145 psi(1 000 kPa)

30

Modules

The Transmission Control

Electronic Control

The Transmission Control Module J217has a dynamic control program forcalculating the nominal transmission inputspeed. It is an improved version of thedynamic shift program (DSP) already beingused in multi-step automatic transmissions.The driver input and vehicle operating stateare evaluated to provide the best gear ratioin every driving situation (see “DynamicControl Program,” page 82).

The dynamic control program calculates anominal transmission input speeddepending on conditions.

The Sensor for Transmission RPM G182registers the actual transmission inputspeed at pulley set 1.

The Transmission Control Module J217calculates a control current for PressureControl Valve -2- for AutomaticTransmission N216 based on an actual-value/setpoint comparison. PressureControl Valve -2- for AutomaticTransmission N216 produces a controlpressure for the hydraulic reduction valvewhich is almost proportional to thecontrol current.

Transmission control is monitored bychecking the plausibility of the signals fromSensor for Transmission RPM G182 andSender for Transmission Output RPM G195as well as the engine speed.

SSP 228/076

TransmissionControl Module J217

Pressure Control Valve -2- forAutomatic Transmission N216

Sensor forTransmissionRPM G182

Sender forTransmissionOutput RPM G195

31

Modules

SSP 228/076

Hydraulic Transmission Control

Pressure Control Valve -2- for AutomaticTransmission N216 is supplied witha constant pressure of approximately73 psi (500 kPa) by the pilot pressurevalve. Pressure Control Valve -2- forAutomatic Transmission N216 producesa control pressure corresponding tothe control current calculated by theTransmission Control Module J217, whichinfluences the position of the hydraulicreduction valve.

A high control current leads to a highcontrol pressure.

The hydraulic reduction valve transfersthe adjusting pressure to the variabledisplacement cylinder of pulley set 1 or 2,depending on the control pressure.

Pulley Set 1


Pulley Set 2

HydraulicReductionValve

PressureControl Valve-2- forAutomaticTransmissionN216

PilotPressureValve

From theOil Pump

Vented into Oil Sump

Oil Supply


Control Pressure

In the Oil Sump

32

Modules

The hydraulic reduction valve is closed at acontrol pressure of between approximately26 and 32 psi (180 and 220 kPa). At a controlpressure of less than 26 psi (180 kPa), theadjusting pressure is transferred to variabledisplacement cylinder at pulley set 1, andthe variable displacement cylinder of pulleyset 2 is simultaneously vented to theoil sump. The Variator shifts the reductionratio towards the end torque multiplictionratio (overdrive).

If the control pressure is greater than32 psi (220 kPa), the adjusting pressure istransferred to the variable displacementcylinder at pulley set 2 and the variabledisplacement cylinder at pulley set 1 issimultaneously vented to the oil sump.The Variator shifts the reduction ratiotowards the starting torque ratio.

SSP 228/084

End Torque Multiplication Ratio (Overdrive)

Pulley Set 1

Pulley Set 2

HydraulicReductionValve

PressureControlValve -2- forAutomaticTransmissionN216

PilotPressureValve

From the Oil Pump

Vented into Oil Sump

Oil Supply


Control Pressure

In the Oil Sump

33

Modules

The Torque Sensor

Contact Pressure Control

As mentioned before, a suitable oilpressure in the pressure cylinder gives aresultant contact pressure of the taperpulleys. If the contact pressure is too low,slippage of the chain will occur and thechain and pulley sets will be damaged. Anexcessively high contact pressure, on theother hand, will result in loss of efficiency.

The object, therefore, is to set the contactpressure of the taper pulleys as accuratelyand safely as possible according torequirements.

RampShell 1

SSP 228/021

A hydro-mechanical torque sensorintegrated in pulley set 1 statically anddynamically registers the actual torquetransmitted to a high degree of accuracyand sets the correct oil pressure in thepressure cylinders.

The engine torque is transferredto the Variator by the torquesensor only. The contact pressureis controlled hydro-mechanicallyby the torque sensor.

Ramp Shell 2

Pulley Set 1

RampShell 2

34

Modules

Design and Function

The torque sensor essentially comprisestwo shells with seven ramps betweenwhich steel balls are mounted in bearings.Ramp shell 1 is form-fitted to the outputgear of pulley set 1 (output gear wheel ofauxiliary reduction gear step). Ramp shell 2is connected to pulley set 1 by a groovedgearing that allows axial movement and issupported by the torque sensor piston. Thetorque sensor piston serves to regulate thecontact pressure and houses torque sensorspaces 1 and 2.

The shells can be rotated radiallytowards one another, converting thetorque to an axial force (due to the balland ramp geometry).

This axial force acts upon ramp shell 2 andmoves the torque sensor piston which is incontact with the shell.

The control edge of the torque sensorpiston now closes or opens the outlets intorque sensor space 1.

The axial force generated by thetorque sensor serves as a controlforce which is proportional to theengine torque.

The pressure which builds upin the pressure cylinder isproportional to the control force.

SSP 228/022

Torque Sensor Piston

Torque Sensor Space 1

Torque Sensor Space 2

Ramp Shell 1

Grooved Gearing

Ramp Shell 2

35

Modules

Torque sensor space 1 is directly connectedto the pressure cylinder.

The system is designed so the axial forcegenerated as a product of engine torqueand the pressure in the pressure cylinderform a force equilibrium.

In constant conditions of vehicle operation,the outlet bores are only partially closed.The pressure drop produced by opening theoutlet bores (torque sensor) modulates thepressure in the pressure cylinder.

If input torque increases, the outlet boresare initially closed further by the controledge. The pressure in the pressure cylinderrises until a force equilibrium again exists.

If input torque decreases, the outlet boresare opened further. The pressure in thepressure cylinder decreases until the forceequilibrium is restored.

SSP 228/057

PressureCylinder

SSP 228/056

Torque SensorSpace 1

OutletBore

PressureCylinder

ControlEdge

OutletBore

100

75

50

25

02.4 1 0.4

36

Modules

At peak torque levels, the control edgecloses off the outlet bores. If the torquesensor moves any further, it acts as an oilpump. The displaced oil volume causes arapid rise in the pressure inside thepressure cylinder and immediately adjuststhe contact pressure.

Extremely high peak torques canoccur when the vehicle drivesover a pot-hole or if thecoefficient of friction of the roadsurface fluctuates considerably(transitions from black ice toasphalt for example).

Adaptation of contact pressure

depending on transmission ratio

The contact pressure exerted by the taperpulleys depends not only on the inputtorque but also on chain track radius and,therefore, on the actual reduction ratio ofthe Variator.

As the diagram shows, the starting torqueratio (clutch engagement) requires thegreatest contact pressure.

The radius of the chain is smallest in pulleyset 1. For power transmission, only a smallnumber of cradle type pressure pieces arein mesh despite the high input torque.

Therefore, a higher contact pressure isapplied by the taper pulleys until a definedreduction ratio of 1:1 is exceeded.

OutletBore

SSP 228/046

SSP 228/058

PressureCylinder

Con

tact

Pre

ssur

e in

%

Required Contact Pressurefor 25% Torque Requirement

VariatorRatio

Overdrive


Overdrive


Required Contact Pressurefor 100% Torque Requirement

Contact Pressure

37

Modules

Function and Mode of Operation

The ratio-dependent contact pressureis adapted in torque sensor space 2.The pressure level in the pressure cylinderis varied by increasing or decreasing thepressure in torque sensor space 2.The pressure in torque sensor space 2is controlled by two transverse holes inthe shaft of pulley set 1. These holes areopened or closed through axialdisplacement of the variable taper pulley.

The transverse holes are open when theVariator is in the starting torque ratio(torque sensor space 2 is depressurized).

When the Variator changes the ratioto end torque multipliction ratio (overdrive),the transverse holes are shut off initially. Ata defined reduction ratio, the left-handtransverse hole is opened to the pressurecylinder through corresponding holes in thevariable taper pulley.

This allows the oil pressure to betransferred from the pressure cylinder intotorque sensor space 2. This pressurecounteracts the axial force of the torquesensor and moves the torque sensor pistonto the left.

The control edge opens up the outlet boresfurther, reducing the oil pressure inside thepressure cylinder.

The main advantage of the two-stagepressure adaptation process is that a lowcontact pressure can be utilized in themid-ratio range which increases efficiency(refer to illustration SSP 228/046,previous page).

SSP 228/060

Torque Sensor Piston

SSP 228/059

Transverse HolesTorque Sensor Space 2

Variable Taper Pulley

Torque Sensor Space 2Bore

Bore

38

Modules

The Splash Oil Cover

Another special feature of the Variator isthe “splash oil cover” on pulley set 2 whichcounteracts the dynamic pressure buildupin the pressure cylinder.

At high engine speeds, the transmission oilin the pressure cylinder is subjected to highrotation-induced centrifugal forces, whichleads to a rise in pressure. This process isknown as “dynamic pressure buildup.”

A dynamic pressure buildup is undesirablebecause it unduly increases the contactpressure and has an adverse effect ontransmission control.

The oil confined in the splash oil cover issubjected to the same dynamic pressurebuildup as in the pressure cylinder. Thedynamic pressure buildup in the pressurecylinder is compensated by this.

The splash oil chamber receives its oilsupply directly from the hydraulic controlmodule through an oil injection hole. Oil iscontinuously injected into the splash oilchamber inlet through this hole.

A reduction in volume inside the splash oilchamber (when varying the transmissionratio) causes the oil to be dischargedthrough the supply inlet.

SSP 228/061

Oil Injection Hole

Splash Oil CoverPulley Set 2

Pressure Cylinder

Splash Oil Chamber

39

Modules

The Chain

The chain is a key component part of theVariator of the multitronic®.

This is the first time that a chain has beenused as a driving means in a CVT.

The chain is a new development and hasthe following advantages over conventionaldriving means such as sliding link beltsor V-belts:

• Very small track radii make possible alarge “spread” despite the small size ofthe Variator.

• High transferable torque.

• High efficiency.

Pulley Set 1

SSP 228/026

The spread indicates the rangeof ratios which a transmissionprovides.

The spread is specified as a ratio.The starting torque ratio dividedby the spread equals to the endtorque multiplication ratio.In general a large spread is anadvantage because both a highstarting torque ratio (for goodperformance) and a low endtorque multiplication ratio (for lowfuel consumption) are available.This applies in particular to theCVT concept, since practicallyall intermediate steps areavailable and no ratio steps areout of place.

Pulley Set 2

Chain

40

Modules

Design and Function

On a conventional chain, the chain linkplates are interconnected by joint pins witha slip fit. For torque transmission, gearteeth move into engagement with the pinsbetween the chain link plates.

The CVT chain uses a

different technology.

The CVT chain has adjacent rows of chainlink plates linked continuously with cradletype pressure pieces (two per link).

On the CVT chain, the cradle type pressurepieces are “jammed” between the taperpulleys of the Variator as the taper pulleysare pressed toward one another.

The torque is transmitted only by thefrictional force between the ends of thecradle type pressure pieces and thecontact faces of the taper pulleys.

This is how it works:

Each of the cradle type pressure pieces ispermanently connected to a row of linkplates so that it cannot be twisted.Two cradle type pressure pieces form acradle type joint.

The cradle type pressure pieces now roll offone another with very little friction as they“drive” the chain within the track radius ofthe taper pulleys.

In this way, lost power and wear areminimized despite the high torque and thelarge angle of bend. The result is longservice life and optimal efficiency.

Cradle TypePressure Piece

SSP 228/027

Taper Pulley of the Variator

Cradle TypePressure Pieces

Top

View

Shackle

Side

View

CradleType Joint

41

Modules

Acoustic Measures

Two different lengths of link plate are usedto ensure that the chain runs as quietlyas possible.

When using a constant length oflink plate, the cradle type pressurepieces strike the taper pulleys at uniformintervals and induce vibrations which causea noise nuisance.

Using different lengths of link platecounteracts resonance and minimizesrunning noise.

SSP 228/028

Different Lengthsof Link Plate

42

Modules

The Oil Supply

In the multitronic®, power transmission isdependent on the electrical power supplyand also on the hydraulics.

In order to work, an electric current and

adequate oil supply are required.

The oil pump is the main power consumerin the transmission and its capacity isimportant for overall efficiency.

The transmission control and coolingsystems are designed to run on a minimumof oil, and an innovative oil supply systemhas been developed.

Intake Filter

The Oil Pump

The oil pump is mounted directly on thehydraulic control module to avoidunnecessary interfaces. The oil pumpand the control module form a compactunit, which reduces pressure losses andproduction costs.

The multitronic® is equipped with anefficient crescent pump. This pumpproduces the necessary pressures, butrequires only a relatively small quantity ofoil. A suction jet pump (entrainment pump)supplies the additional quantity of oilrequired for the clutch cooling at lowpressure. The compact crescent-vanepump is integrated in the hydraulic controlmodule and driven directly by the inputshaft by a spur gear and pump shaft.

SSP 228/034

HydraulicControl Module(Valve Body)

Pressure Tube Routedto Suction Jet Pump(Entrainment Pump)

Oil Pump

43

Modules

As a special feature, the oil pump has axialand radial clearance adjustment.

A pump with good “internal sealing” isrequired in order to produce high pressuresat low engine speeds.

“Internal sealing” refers to theability of the pump to minimizeleakage past the surfaces movingthe fluid through the pump.

SSP 228/035Axial Plates

Conventional oil pumps do not meetthese requirements due to componenttolerances.

The axial clearance between the gearsand the housing, as well as the radialclearance between the gears and thecrescent vane can vary depending on thetolerance zone position of the componentparts in a conventional pump.

The pressure generated can thus more orless escape “internally.”

The result will be a loss of pressure and adrop in efficiency.

Segmental SpringsSealing Roller

Stop PinInner Segment

Spring Rod

Oil Pump Housing

Outer Segment

Driver

44

Modules

Axial Clearance Adjustment

Two axial plates cover the pressure rangeof the crescent pump and form a separatedischarge casing inside the pump.They seal the pump pressure chamberlaterally (axially). These plates, fitted witha special seal, are supported by the oilpump housing or the pump plate of thehydraulic control module.

The axial plates are designed to allow thepump pressure to act between the axialplates and the housing. The seal preventspressure from escaping. As pump pressure

SSP 228/051

increases, the axial plates are pressedmore firmly against the crescent seal andthe pump gears, which compensates foraxial clearance.

The axial and radial clearanceadjustment allows the pump togenerate the required highpressures and simultaneouslyachieve high efficiency despite itscompact design.

Seal

Axial Plate

Oil Pump Housing

Axial Plate

Axial Plate

45

Modules

Radial Clearance Adjustment

The radial clearance adjustment featurecompensates for the radial gap betweenthe crescent seal and the gears (pinion andring gear).

For this purpose, the crescent seal is splitin two segments, the inner segment andthe outer segment.

The inner segment seals the pressurechamber off from the pinion. It also holdsthe outer segment in a radial direction.The outer segment seals the pressurechamber off from the ring gear. The pumppressure flows between the two

SSP 228/049

Inner Segment

segments. The segments are pressedmore firmly against the pinion and ring gearas the pump pressure increases, whichcompensates for radial clearance.

When the pump is depressurized, thesegmental springs provide the basiccontact pressure for the segments and thesealing roller, and improve the suctioncharacteristics of the oil pump.

They also ensure that the pump pressurecan act between the segments and on thesealing roller.

Crescent SealOuter Segment

Pinion

Ring Gear

46

Modules

The Suction Jet Pump

(Entrainment Pump)

The quantity of oil required to ensuresufficient cooling of the two clutchesexceeds the capacity of the internal gearpump, particularly when pulling away(there is high heat buildup due to slip).

SSP 228/036

View of Suction Jet Pump

(Entrainment Pump)

Pressure Tube(Routed toforward clutch)

Inlet Pipe

Pressure Tube(Routed from hydrauliccontrol moduleto suction jet pump(entrainment pump))

ATF Overflow Pipe

A suction jet pump (entrainment pump) isintegrated in the clutch cooling system tosupply the quantity of oil required forcooling the clutch.The suction jet pump (entrainment pump) ismade of plastic and projects deep into theoil sump.

47

Modules

SSP 228/037

Suction Jet Pump (Entrainment Pump)

(Shown in Profile and Folded Out)

CheckValve

VenturiNozzle

This is how it works:

The suction jet pump (entrainment pump)operates according to the Venturi principle.When the clutch requires cooling, thecooling oil (pressurized oil) supplied by theoil pump is ducted through the suction jetpump (entrainment pump) in the formof a powerful jet. The oil flow through theentrainment pump nozzle results in a partialvacuum which “sucks” oil out of the oilsump and, together with the powerful jet,results in a large, almost depressurizedquantity of oil.

The quantity of cooling oil is almostdoubled as required without additionalpumping capacity.A check valve prevents the suction jetpump (entrainment pump) from running dryand facilitates a quick response of thecooling oil feed.

48

Modules

Electro-Hydraulic Control

A new feature is that theoil pump, hydraulic controlmodule (valve body) andTransmission Control ModuleJ217 are combined as acompact assembly.

Selector Shaft

The hydraulic control module containsthe manual selector valve, nine hydraulicvalves and three electromagnetic pressurecontrol valves.

The hydraulic control module and theTransmission Control Module J217 areconnected electrically by direct plug-incontacts.

SSP 228/063

Oil Pump

ManualSelectorValve

Transmission ControlModule J217

Direct Plug-In Contact

Hydraulic Control Module

49

Modules

The hydraulic control module executes thefollowing functions:

• Forward-reverse clutch control

• Clutch pressure regulation

• Clutch cooling

• Pressurized oil supply to the contactpressure control

• Transmission control

• Supplying the splash oil cover

The hydraulic control module isconnected directly to pulley set 1 andpulley set 2 by “screw inserts.”

The screw inserts are sealed by O-rings.

Screw Inserts for Pulley Set 1

SSP 228/085

Screw Inserts for Pulley Set 2

O-Ring

Oil Injection Hole forSplash Oil Cover

O-Ring

50

Modules

Sectional View of Valve Plate

SSP 228/047

The descriptions of the valves that followrefer to valves not included in the previousmodule/function descriptions:

To protect the component parts, pressure

limiting valve 1 limits the pump pressureto maximum 1189 psi (8 200 kPa).

The pressure control valves aresupplied with a constant pilot controlpressure of 73 psi (500 kPa) by thepilot pressure value.

SSP 228/044


(Transmission Control Module J217 Removed)

Connection toAutomaticTransmissionSender -1-for HydraulicPressure G193

ElectricalConnectorfor N88



PressureLimitingValve 1

Connection toAutomaticTransmissionSender -2-for HydraulicPressure G194

Pressure ControlValve -2- forAutomaticTransmissionN216

SolenoidValve 1N88

PilotPressureValve

PressureControl Valve-1- forAutomaticTransmissionN215

ClutchControlValve

MinimumPressureValve

PressureLimitingValve 1Clutch

CoolingValve

The minimum pressure valve preventsthe oil pump drawing in engine air whenthe engine is started. When pump output ishigh, the minimum pressure valve opensand allows oil to flow from the oil returnpipe to the suction side of the oil pump;this improves efficiency.

51

Modules

The pressurizing valve controls thesystem pressure so that sufficient oilpressure is always available for a particularfunction (application of contact pressureor adjustment).

Solenoid Valve 1 N88, Pressure ControlValve -1- for Automatic Transmission N215,and Pressure Control Valve -2- forAutomatic Transmission N216 are designedas “pressure control valves.”

They convert an electric control current to aproportional, hydraulic control pressure.

The Solenoid Valve 1 N88 controls theclutch cooling valve and the safety valve.Pressure Control Valve -1- for AutomaticTransmission N215 actuates the clutchcontrol valve. Pressure Control Valve -2- forAutomatic Transmission N216 actuates thereduction valve.

Sectional View of Pump Plate

ReductionValve

SSP 228/048

SafetyValve

ManualSelectorValve

VolumetricFlow RateLimiting Valve

PressurizingValve

SSP 228/100

Current in mA

SSP 228/101

Diagram of Pressure Control Valve

Con

trol

Pre

ssur

e in

psi

(kP

a)

Pressure Control Valve

(Proportional Valve)

0 (0)0 1000

73 (500)

52

Modules

Selector Shaft and Parking Lock

A mechanical connection (cable pull) fortransmission of selector lever positions P,R, N and D still exists between the gateselector lever and the transmission.

The following functions are executed viaselector shaft:

• Actuation of the manual selector valve inthe hydraulic control module, i.e.hydromechanical control of vehicleoperating state (forward/reverse/neutral).

• Operating the parking lock.

• Actuation of the multi-functional switchfor electronic recognition of the selectorlever position.

SSP 228/065

Actuation ofthe Outer SelectorMechanism

In selector lever position P, the linkagewith locking teeth is displaced axially sothat the parking lock ratchet is pressedagainst the parking lock gear and theparking lock is engaged.

The parking lock gear is permanentlyconnected to the drive pinion.

Parking Lock Ratchet

Linkage with Locking Teeth

Pulley Set 2

Detent Gate

Drive Pinion

Magnetic Gate

Parking Lock Gear

Manual Selector Valve

Selector Shaft

53

Modules

Transmission Housing Ducting

and Sealing Systems

Sheathed Sealing Ring System

The multitronic® is equipped with a newsheathed sealing ring system.

The sheathed sealing rings seal thepressure cylinder and the variable-displacement cylinder of pulley set 1,the pulley set 2, and the piston forthe forward clutch.

The O-ring presses down and seals thesheathed sealing ring.

The oil pressure present assists thesheathed sealing rings with contactpressure application.

Advantages of the sheathed sealing ringsystem:

• Good anti-friction properties

• Low displacement forces

• Wear is minimized

• Stable at high pressures

SSP 228?062

Double-Corrugated Sealing Ring

O-Ring

SheathedSealing Ring

54

Modules

To save weight, the three-piecetransmission housing is manufacturedfrom the AZ91 HP magnesium alloy.This alloy is highly corrosion resistant,easy to process and has a 17.6 lb (8 kg)weight advantage over a conventionalaluminum alloy. As a special feature,the ATF pressurized oil is not distributedthrough housing ducts as is usual onautomatic transmissions, but almostexclusively by pipes.

Axial sealing elements are used to sealthe pipe connections. The axial sealingelements of the pressure pipes have twosealing lips which apply a higher contactpressure as a result of the oil pressure, andtherefore seal the pipes reliably. Diagonalpipe connections can also be sealedwithout difficulty using this technology (e.g.pressure tube connected to reverse clutch).The oil pump intake fitting axial sealingelement has sealing beads which seal thefitting by contact pressure.

The double-corrugated sealing ring (seepage 53) separates the ATF reservoirfrom the final drive oil reservoir. It preventsthe ATF from entering the final drive andoil from the final drive entering theATF reservoir.

Leaks in the double-corrugated sealing ringbecome visible at the oil return hole.

Groove forDouble-CorrugatedSealing Ring

Inner Section

Pressure Tube Routedto Reverse Clutch

Differential PressureValve 1 withATF Strainer 1

Oil Return Hole

55

Modules

Pressure Tube Routed toSuction Jet Pump (Entrainment Pump)

SSP 228/041

Oil Drain Screw

Suction Jet Pump (Entrainment Pump)

ATF Inspection Plug

Axial Sealing Element

Pressure Tube Routed toForward Clutch

ATF Level

Intake Filter

Return Pipe from ATF Coolerwith Spray Nozzles for Chainand Pulley Sets

56

Modules

Hydraulic Circuit Diagram

23

Pulley Set 1

2 Pulley Set 2

7

3

4 5 19

22

2011

26

28

15

18 6

27

24 9

8 30

1410

13

25

31

1

29

12P R N D

21

16

SSP 228/039

32

17

57

Modules

Hydraulic Circuit Diagram Legend

(Selector Lever Position P

and Engine “OFF”)

1 Pressure Limiting Valve 12 Pressure Limiting Valve 23 Differential Pressure Valve 14 Differential Pressure Valve 25 ATF Filter6 Manual Selector Valve7 ATF Cooler8 Clutch Cooling Valve9 Clutch Control Valve

10 Minimum Pressure Valve11 Measuring Point for Contact

Pressure (Registered by G194)12 Measuring Point for Clutch Pressure

(Registered by G193)13 Solenoid Valve 1 N88

(Clutch Cooling/Safety Shut-Off)14 Pressure Control Valve -1- for

Automatic Transmission N215 (Clutch)15 Pressure Control Valve -2- for

Automatic Transmission N216 (Ratio)16 Oil Pump17 Selector Lever Position PRND18 Reverse Clutch19 ATF Strainer 120 ATF Strainer 221 ATF Strainer 322 Four Spray Holes for Pulley Set

Lubrication/Cooling23 ATF Intake Filter24 Safety Valve25 Suction Jet Pump (Entrainment Pump)26 Reduction Valve27 Forward Clutch28 Volumetric Flow Rate Limiting Valve29 Pressurizing Valve30 Pilot Pressure Value31 To Splash Oil Cover32 To the Clutches

Differential Pressure Valve 1and ATF Strainer 1

SSP 228/071

Pressure Limiting Valve 2 inthe Transmission Housing

Return Pipe fromATF Cooler

In the Oil Sump


Peripheral Components inthe Vehicle

58

Modules

ATF Cooling

The ATF coming from pulley set 1 initiallypasses through the ATF cooler. The ATFflows through the ATF filter before it isreturned to the hydraulic control module.

The ATF cooler is integrated in the radiator.Heat is exchanged with the coolant inthe engine cooling circuit (oil-coolantheat exchanger).

The differential pressure valve 1 protectsthe ATF cooler against excessively highpressures (ATF cold). When the ATFis cold, a large pressure differencedevelops between the supply line and thereturn line. When a specific pressuredifferential is reached, the differentialpressure valve 1 opens and the supply line

is short-circuited with the return line tobypass the ATF cooler. This also causesthe temperature of the ATF to rise tonormal operating temperature rapidly.

The differential pressure valve 2 openswhen the flow resistance of the ATF filter istoo high (e.g. filter blockage). This preventsthe differential pressure valve 1 fromopening and the ATF cooling system frombeing disabled by the backpressure.

If the ATF cooler is leaky, coolantcan enter the ATF. Even smallquantities of coolant in the ATFcan have an adverse effect onclutch control.

SSP 228/090

Peripheral Components in the Vehicle

To HydraulicControl Module

ATF Filter

multitronic®

PressureLimitingValve 2

Supply Line

ATF Cooler

ATF FilterReturn LineDifferential

PressureValve 2

ATF Strainer 1

DifferentialPressureValve 1

FromPulleySet 1

Supply Line

Return Line

Modules - europeantransmissions.com · 9 Modules SSP 228/040 Housing, Screws, Bolts Hydraulic...

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Transcript of Modules - europeantransmissions.com · 9 Modules SSP 228/040 Housing, Screws, Bolts Hydraulic...