E90 Driving Dynamics Systems.pdf

Participant's ManualDynamic Driving Systems E90BMW Service Aftersales Training

The information contained in this Participant's Manual is intended solely for the participants ofthis seminar run by BMW Aftersales Training.

Refer to the latest relevant "BMW Service" information for any changes/supplements to theTechnical Data.

Information status: October 2004

[email protected]

2004 BMW GroupMnchen, Germany. Reprint of this manual or its parts require the written approval oftheBMW Group, Mnchen.VS-12 Aftersales Training

Participant's ManualDynamic Driving Systems E90

Dynamic Stability Control (DSC)

Longitudinal Dynamics Management(LDM)

Dynamic Cruise Control (DCC)

Active Cruise Control (ACC)

Active Front Steering (AL)

Information on this Participant's Manual

Symbols used

The following symbols are used in this Participant's Manual to facilitatebetter comprehension and to draw attention to important information.

3 contains information for better understanding of the describedsystems and their functions.

1 identifies the end of an item of information.

Current content of Participant's Manual

In view of the constant further developments in the design and equipmentof BMW vehicles deviations may arise between this Participant's Manualand the vehicles made available as part of the training course.

The background material refers exclusively to left-hand drive vehicles.The controls are in part arranged differently in right-hand drive vehiclesthan shown on the graphics in the Participant's Manual.

Additional information sources

You will find further information on the individual vehicle topic in the BMWdiagnosis and repair systems as well as on the Internet underwww.bmw.com.

ContentsDynamic Driving SystemsE90

Objectives 1Purpose of this Participant's Manual 1

Introduction 3

8ObjectivesDynamic Driving Systems E90

Purpose of this Participant's Manual

The Participant's Manual is a documentdesigned to accompany a seminar while at thesame time serving as a source of reference.

The new developments in relation to thedynamic driving systems for the E90 modelseries are described in this Participant'sManual.1

9IntroductionDynamic Driving Systems E90

Many further developments in the E90

The dynamic driving systems in the E90 arefor the most part further developments ofestablished systems.

Exceptions are Longitudinal DynamicsManagement (LDM) and the new availability ofdrive assist systems in a mid-size classvehicle.3

ContentsDynamic Stability Control(DSC) E90

Introduction 1Variants 1

System overview 3MK60E5 - a further development of theMK60psi 3

8IntroductionDynamic Stability Control (DSC)

Variants

There will provisionally be two different DSCmodules when the new 3 Series Saloon (E90)is launched onto the market:

The four-cylinder models of the E90 willfeature the MK60psi from ContinentalTeves, which was used for the first time inthe E87.

The six-cylinder models of the E90 willfeature the MK60E5 from ContinentalTeves.

3 The lettering on the button has beenchanged in the E90 for all variants from DSC toDTC (Dynamic Traction Control). 1

Features of the MK60psiThe abbreviation "psi" stands for "pressuresensor integrated". This means that the twopressure sensors on the tandem brake mastercylinder (THZ) which have measured a brakepressure request have been combined tocreate a single plausibility sensor. Theplausibility sensor has been integrated in thehydraulic control unit.

Additionally:

Two-stage brake pad wear indicator incl.remaining-mileage calculation within theframework of requirement-orientatedservice (BOS)

Link betweenthe DSC control unit and theCar Access System (CAS) to facilitate anelectric steering lock (ELV) function

Higher integration density in terms ofsensors and control unit network in thevehicle.

Features of the MK60E5The features of the system are characterizedby significantly improved comfort duringcontrol interventions and by even moreprecise single-wheel braking thanks to theanalogue control performance of the inputcontrol valves. This is achieved by means of apulse-width-modulated signal (PWM).

It has been possible among other thing toreduce the braking distance to a minimum andto realize some new functions. The newfunctions contribute to increased directionalstability, optimized comfort and improvedsystem availability.

New functions:

Fading support

Braking readiness

Dry braking

Soft stop function

Start assist

ECBA interface (Electronic Control BrakeActuation) for ACC

Yaw moment compensation in associationwith active front steering (AL).1

9System overviewE90 Dynamic Stability Control

MK60E5 - a further development of the MK60psi

The MK60E5 (also installed in the E60 M5) isa further development of the MK60psi, whichis used in the E87 and in the E90 with four-cylinder engines.

In the MK60E5 the designation "E5" standsfor the 5 pressure sensors which areintegrated in the hydraulic control unit:

A combined pressure sensor on the inletside which monitors the plausibility of thepressures of the tandem brake mastercylinder (THZ)

Four further sensors on the outlet sidewhich measure the braking pressure of theassigned wheel brake

The MK60E5 DSC has as usual a DTCfunction and also a Runflat Indicator (RPA).

The lettering on the button has been changedin the E90 from DSC to DTC.3

91 - DSC E90 hydraulic circuit diagram4

9Sensors

* Wheel-speed sensorsGrey grommet = MK60E5 with direction-of-rotation detection (since the braking responsewhen reversing is different from that whendriving forwards, output to navigation system,

EGS etc.)Black grommet = MK60psi

** For the start assist function

Control unit Add-on control unit

Integrated semiconductor relays (engineand valve relays)

High computing capacity is provided by a2 MB flash processor

3 The control unit may only be replacedseparately after the end of the first year; beforethis, it may only be replaced together with thehydraulic control unit! 1

Index Explanation Index Explanation

1 Brake fluid expansion tank 12 Inlet valve, front right, withswitching orifice, analogue

2 Rear-axle brake circuit 13 Inlet valve, rear right, analogue

3 Front-axle brake circuit 14 Inlet valve, rear left, analogue

4 Pressure sensor, push rod circuit 15 Outlet valve, rear left

5 Pulsation damper 16 Outlet valve, rear right

6 Isolating valve 17 Outlet valve, front left

7 Electric changeover valve 18 Outlet valve, front right

8 Self-priming return pump 19 Wheel brake, front right

9 Damper chamber 20 Wheel brake, front left

10 Accumulator chamber 21 Wheel brake, rear right

11 Inlet valve, front left, with switchingorifice, analogue

22 Wheel brake, rear left

Sensor system Functional principle Manufacturer

Active wheel-speed sensors* Magneto-resistive principle Teves

Steering angle sensor (LWS) insteering column switch cluster (SZL)

Optoelectronic

Yaw rate sensor Twin tuning fork principle Teves

Lateral-acceleration sensor Capacitive principle Teves

Longitudinal-acceleration sensor** Integrated in control unit

5 pressure sensors Integrated in hydraulic block

Brake light switch Hall principle

Brake-fluid level switch Reed contact switch5

A longitudinal-acceleration sensor has beenintegrated in the DSC control unit in orderto realize the start assist function

9Hydraulic control unit

Continental Teves MK60E5

3 Available for the E90 in LHD and RHDversions (different part numbers). 1

Front axle

2 inlet valves

2 high-speed outlet valves

Rear axle

2 inlet valves

2 high-speed outlet valves

Pressure generation

Pump with two stepped piston pumpelements

Actuated via a common eccentric shaft

ASC (Automatic Stability Control) and DSCoperation: self-priming return pump

Power-optimized pump motor (250 W)

Engine interventions

Ignition timing

Charge adjustment

Interfaces

CAN bus interface (F-CAN, PT-CAN)

Additional DSC functions

ECBA interface (Electronic ControlBrake Actuation) for ACC via LDM(Longitudinal Dynamics Management)

The ACC request in the DSC with regard topressure build-up, pressure recording andmodulation at the wheel brakes is optimallyimplemented in terms of deceleration andcomfort via the ECBS interface.

Yaw moment compensation inassociation with AL

In conjunction with AL, it is possible for abraking yaw moment created by differentfriction coefficients, which was previouslystabilized by DSC control, to be compensatedwithout a reduction in braking power by an ALcorrection. For further details, see AL.

Fading support

For the purpose of setting a constant ratio ofpedal force to vehicle deceleration, the brakepressure is increased in line with anarithmetical temperature model in order tocompensate fading effects (if necessary,increased pedal travel in the event of brake

releasing the accelerator pedal, the air gap ofthe brake pads is bridged by a slight volumefeed into the brake calipers, therebyestablishing spontaneous braking readinessfor the driver.

Dry braking

A further function for increasing safety isachieved by deceleration-free "dry braking" asneeded of the brake discs with a slightapplication of the brake pads. The trigger forthis function is the information on the rainsensor or on an active windscreen wiperactivity.

Soft stop function

The uncomfortable jolt as the vehicle comesto a stop familiar primarily from cars withautomatic transmissions is compensated withthe function through a specifically controlledreduction of pressure shortly before thevehicle comes to a stop.

Start assist

This function briefly holds the vehicle, thereby6

heating).

Braking readiness

Braking readiness is established by DSCthrough an "initial application" of the brakepads. When DSC detects a brakingmanoeuvre to be expected, e.g. suddenly

allowing the driver to restart the vehicle withno rolling back on an uphill or downhill gradientwithout constantly having to depress thebrake pedal or apply the parking brake.

ContentsLongitudinal DynamicsManagement (LDM)

Introduction 1

System overview 3

8IntroductionLongitudinal Dynamics Management (LDM)

The new Longitudinal Dynamics Managementsystem is provisionally installed in the E90 onlyin conjunction with ACC or DCC, i.e. it is onlyused in the six-cylinder models.

In previous BMW vehicles, accelerationcontrol, such as "accelerating" or braking(negative acceleration), was calculated bydifferent systems (DME/DDE, DSC, ACC etc.)in order then to activate the correspondingactuators with the relevant control signals.

This created a problem in that there was abuild-up of a whole host of variants (engine,transmission and brake variants). In an E65, forexample, there were 36 relevant car/engine/transmission variants.

In order to take control of the increasingcomplexity over the course of time and theincrease in variants, BMW has taken thedecision to implement only one accelerationcontroller in the E90 vehicle network. Thiscontroller records the requests on the inputside, calculates the corresponding setpointvariables and forwards them to the systempartners such as DME/DDE, EGS, DSC, etc.Connected to a longitudinal-force controller, itcoordinates and controls the actuators in allthe vehicle configurations. The LongitudinalDynamics Management system (LDM) ishoused in an independent new control unitwhich is located in the E90 behind the lightmodule.

1 - Longitudinal, transversal and vertical dynamics

Index Explanation

1 Longitudinal dynamics

2 Transversal dynamics

3 Vertical dynamics1

9System overviewLongitudinal Dynamics Management (LDM)

The LDM is a control unit which is used fordrivetrain and brake coordination purposes. Itprovides significantly improved automaticcruise control (ACC, DCC) with a generalcontrol function ranging from accelerating tobraking.

Interface: CAN bus interfacePT-CAN.

1 - Installation location of control unit

Index Explanation

1 LDM control unit3

9The LDM has two important primary functionsto fulfil:

Variant handling

LDM functions are configuration-dependent (coding-relevant function)

LDM safety and functions are ensured by acentral monitoring and redundancy system.

2 - Bus overview


1 Wheel torque for braking DME/DDE

Digital Motor Electronics/DigitalDiesel Electronics

2 Wheel torque for accelerating DCC Dynamic Cruise Control

3 Gearshift request DSC Dynamic Stability Control

A a_setpoint EGS Electronic transmission controlACC Active Cruise Control LDM Longitudinal Dynamics

Management4

93 - LDM functions


1 Operator interface D a_interference factor

2 Display interface E M_wheel_actual_drive

3 Status control F M_wheel_setpoint

4 Vehicle speed controller G M_wheel_setpoint_brake

5 Lateral-acceleration controller H M_wheel_setpoint_drive

6 Comfort dynamics ACC Active Cruise Control

7 Prioritizer (minimum formation) AHM Trailer module

8 Interference factor estimator DDE Digital Diesel Electronics

9 Acceleration controller DME Digital Motor Electronics

10 Drive/brake coordination EGS Electronic transmission control5

11 Monitoring KOMBI Instrument cluster

A V_actual, V_setpoint LDM Longitudinal DynamicsManagement

B V_actual, yaw rate SZL Steering column switch cluster

C a_setpoint

9FunctionsImplemented functions in the LDMcontrol unit

"OPERATOR INTERFACE" module (1):Receives e.g. from the steering columnstalk the "Acceleration" signal request,assigns this to a function and forwards it tothe "Status control" module.

"DISPLAY INTERFACE" module (2):Controls the output of information to thedriver (e.g. display of desired speed, desireddistance, driver takeover request) which isoutput by the "STATUS CONTROL"module.

"STATUS CONTROL" module (3):Evaluates the specifications by the driverand assigns each of them to one of thethree processing modules responsible. Thevariables here are speed (v), setpoint/actualand yaw rate.

"VEHICLE SPEED CONTROLLER"module (4):Calculates the acceleration/decelerationsetpoint variable on the basis of the desiredspeed and the deviating actual speed.

"LATERAL-ACCELERATIONCONTROLLER" module (5):Reduces the lateral acceleration in thebend/curve to an appropriate value and ifnecessary initiates an intervention whencornering. The actual lateral acceleration iscalculated from the actual speed and afault-corrected yaw rate.

"COMFORT DYNAMICS" module (6):Available to the driver for specifying theacceleration and deceleration in the "CC"mode and is established here in the outputof an acceleration/deceleration setpointvariable.

"PRIORITIZER" (7):Decides which acceleration setpoint valueis used by the cruise control and ifnecessary adaptive cruise control andwhich rate-of-change limiting is used in the"ACCELERATION CONTROLLER"module.

calculates an acceleration/decelerationinterference correction variable.

"ACCELERATION CONTROLLER"module (9):Converts the selected setpoint accelerationinto an overall manipulated variable (totalwheel torque) for drive and brake.The acceleration controller has to ensurethat the specified setpoint acceleration ofthe vehicle (drive) is also achieved with thepresence of external interference factors,such as e.g. uphill/downhill gradient. Theacceleration controller ensures comforttypical for drive assist systems, such as e.g.jolt-free performance.

"DRIVE/BRAKE COORDINATION" module(10):Coordinates and controls the systempartners DME/DDE, EGS and DSC, byoutputting a setpoint wheel braking torqueand a brake release signal to the DSC and asetpoint wheel drive torque with driverelease to the DME/DDE.

"MONITORING" module (11):Monitors all the signal variables coming intothe LDM. The programmed safetymeasures are also implemented here.

The LDM has the following interfaceparameters in the E90:

Steering column switch cluster (SZL)

Instrument cluster (KOMBI)

Brake (DSC)

Drive (DME/DDE and EGS)

Active Cruise Control (ACC sensor; optionalextra)

Driver's footwell module (FRMFA;direction indicator)

ANTICIPATORY ACTION for theovertaking assist function (directionindicator) - Only with ACC!

Car Access System (CAS; terminal status)

Trailer module (AHM; interference factor:6

"INTERFERENCE FACTORESTIMATOR" module (8):Estimates the acceleration interferencefactors (e.g. uphill/downhill gradient, rollingresistance) from the actual wheel drivetorque and the changes to the vehicle massdue to the additional mass of a trailer and

mass)

9Service informationThe LDM is:

codable

programmable

capable of self-diagnosis

An LDM failure is not signalled directly to thedriver but is visible in the form of DSC/ACC/DCC indications in the instrument cluster.7

ContentsCruise control withbraking function (DCC)

Introduction 1Cruise control with braking function (DynamicCruise 1

System overview 3Functions 3

8IntroductionCruise control with braking function (DCC)

Cruise control with braking function (Dynamic CruiseControl DCC)

In the new E90 the customer can choosebetween three cruise control systems, whichare however also dependent on the enginevariant:

Option 540: Cruise control (FGR), for four-cylinder models

Option 541: Active Cruise Control (ACC) forsix-cylinder models

Option 544: Cruise control with brakingfunction (DCC), for six-cylinder models

ACC and DCC in the E90 need to becombined with an LDM, where the cruisecontrol today still manages without this newcontrol unit and as usual forwards its driverrequest signals directly to the DME/DDE.

1 - Steering column stalk withDCC function

Index Explanation

1 Steering column stalk with DCC function1

9System overviewCruise control with braking function (DCC)

Functions

The new cruise control with brake interventionmaintains the set speed at a constant leveleven on downhill gradients by means ofindependent brake interventions.

DCC can be activated from 30 km/h (settableup to max. 250 km/h) and is deactivated bysimilar factors as for cruise control:

Brake pedal actuation

Deactivation of DSC

Activation of DTC

Active DSC intervention

Deactivation by the driver

Speed is reduced below 20 km/h

In manual gearboxes: excessively longclutching operation (approx. 4 s, seeDiagnosis)

In automatic transmissions: selection of "N"

DCC achieves a deceleration of max.-2.5 m/s2 and an acceleration of approx.+1.2 m/s2.

The lateral acceleration is restricted to max.4.0 m/s2.

The primary emphasis has been placed oncomfortable performance in this systemconfiguration.

When the cruise control is activated, the brakelights are activated in the event of system-dictated braking (DCC) (required by law).

Unlike conventional cruise control, the driver inthe E90 in DCC mode and with a manualgearbox can actuate the clutch and performgearshifts without the system beingdeactivated. If however the driver does not payattention to the gearshift request, the DCC isdeactivated during slower driving at very highor very low engine speeds.

In the event of an automatic deactivation, thefollowing Check Control message (CC)appears:

The following Check Control messageappears if the system malfunctions:

1 - CC message, cruise control

2 - CC message, cruise control3

ContentsActive Cruise Control(ACC)

System overview 1Active Cruise Control 1Functions 3

9System overviewActive Cruise Control (ACC)

Active Cruise Control (ACC)

IntroductionWith the introduction of the new ACC in theE63/E64 (6 Series), the system can bereferred to as a 2nd generation ACC. This

further developed ACC is now offered in theE90. A connection to the navigation system isnot envisaged in the E90 with ACC.

Differences of "Active Cruise Control" option in E90 from optionin E63/E64:The ACC control unit has been changed fromthe control unit for the "intelligent sensor" bythe combination with the LDM because thefunctions are now evaluated and calculated inthe new Longitudinal Dynamics Managementcontrol unit.

1 - ACC sensor in the E90

Index Explanation

1 Installation location, ACC sensor1

9Differences of 2nd generation ACC option from 1st generationACC (e.g. E60 before 03/05):

ACC sensor (control unit) is 60 % smallerthan previously

4 instead of 3 radar beams

Horizontal opening angle of the radarsensor now 8 instead of 4

Also new signal processing due to thehigher data density (opening angle, 4beams)

Anticipatory acceleration action by ACC inthe event of an imminent lane changethrough setting of the direction indicator bythe driver.

Customer benefits of 2nd generation ACC: Earlier reaction to vehicles which cut in in

front of own vehicle

More stable following driving (bend/curvedetection):

On tight motorway bends/curves

At motorway sliproads/exits

On winding country roads

2 - Opening angle and radar beams2

9Functions

The Active Cruise Control system has DCCfunctions and also automatic adaptive cruisecontrol functions.

ACC can be activated from 30 km/h up to max.180 km/h and is deactivated by similar factorsas for DCC:

Brake pedal actuation

Deactivation of DSC

Activation of DTC

Active DSC intervention

Deactivation by the driver

Speed < 22 km/h

In manual gearboxes: excessively longclutching operation (approx. 4 s, seeDiagnosis)

In automatic transmissions: selection of "N"

ACC achieves a deceleration of max. -2.5 m/s2

and an acceleration ofapprox. + 1.2 m/s2.

The lateral acceleration is restricted to max.4.0 m/s2.

The primary emphasis has been placed oncomfortable performance in this systemconfiguration as well.

3 No safety system! 1

When the cruise control is activated, the brakelights are activated in the event of system-dictated braking (ACC) (required by law).3

ContentsActive Front Steering (AL)

System overview 1Introduction 1Functions 4

9Option 217 Active Front Steering in the E90can currently only be ordered for customers inthe six-cylinder models. Servotronic in the E90

The mechanical layout of the steering systemhas undergone only minor changes and hasbeen adapted to the space conditions in theE90.System overviewActive Front Steering (AL)

Introduction

One of the important further developments inthe field of Active Front Steering is thecombination of braking and steeringinterventions as this delivers a whole newquality of directional stability in the E90.

is only available in conjunction with ActiveFront Steering (no Option 216 as in the E60).1

9The installation location of the AL control unit

1 - Overview of Active Front Steering mechanical components


1 Cumulative steering angle sensor 5 Steering spindle

2 Rack 6 Electric motor

3 Planetary gear housing 7 Motor position sensor

4 Magnetic interlock2

is new in comparison with the E60 in that thecontrol unit is no longer situated in the frontpassenger footwell but rather in the front leftwheel arch underneath the wheel arch trim.

92 - AL control unit

Index Explanation

1 Installation location, AL control unit3

9Functions

Previous functions of AL: The steering ratio is dependent on the

steering wheel angle and the vehicle speed

More manoeuvrability and agility at lowerand mid-range speeds

Improved comfort when manoeuvring inand out of parking spaces and othermanoeuvring (less gripping)

Increased monitoring and safety duringdynamic steering manoeuvres (handsfirmly on the steering wheel)

Stable straightline stability at highspeeds

Linking with Servotronic (common tuning ofsteering ratio and steering force level) andan ECO valve for hydraulic delivery

Stabilization intervention dependent on thedriver's steering action

Optimum support of the driver whilemaintaining "accuracy"

Stabilization with all road surfacecoefficients of friction

Early stabilization on account of "morecomfortable" steering intervention

Reduction and postponement of DSCbrake interventions

Linking with DSC

Guaranteed vehicle stability in every roadsituation, also restricted intervention viathe steering.

New functions of AL in the E90: Two different "variable steering tuning"

curves for standard and sport suspensionsin the E90 (coded in the factory)

Two yaw rate sensors in one housing(redundancy and a necessary higherinformation density)

Additional support of the DTC mode

Braking stabilization by yaw momentcompensation.

Yaw moment compensation4

3 - -split braking with ABS

9This new function represents a significantsafety feature. In the case of braking ondifferent road surface coefficients of friction(asphalt, ice or snow), a moment builds upabout the vertical axis (yaw moment) rendering

the vehicle unstable. In this case, DSCcalculates the steer angle for the front wheelsand the active front steering converts thisinput into an active countersteer.

In this way a counter-moment builds up aboutthe vertical axis and the previously created yawmoment is "compensated" (cancelled), i.e. thisvehicle is stabilized by the skilful interplay ofDSC braking and the AL steering function,delivery a new safety aspect unique in this carclass.

This automatic early countersteer isdependent on the difference of the front wheelbraking pressures.

Particular advantage of this function:

It shortens the braking distance becausehigher braking pressure differences at the rearaxle are possible with yaw rate compensationvia the steering. ABS on its own would setsignificantly lower pressure than is actuallypossible at wheels on a high coefficient offriction ("select low") and thus create a longerbraking distance in this situation.

4 - -split braking with DSC and AL5

Abbreviations

ABS Anti-lock braking system

ACC Active cruise control

AHM Trailer module

AL Low beam headlight

Active steering system

ASC Automatic stability control

CAN Controller area network

CAS Car access system

CC Check control

DDE Digital diesel electronics

DME Digital motor electronics

DSC Dynamic stability control

DTC Dynamic traction control

EGS Electronic transmission control unit

ELV Electric steering lock

F-CAN Chassis CAN

FGR Cruise control

KOMBI Instrument cluster

LWS Steering angle sensor

PT-CAN Power Train Controller Area Network

PWM Pulse width modulation

RPA Tyre puncture warning

SZL Steering column switch cluster

THZ Tandem-brake master cylinder

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Participant's ManualInformation on this Participant's ManualObjectivesPurpose of this Participant's ManualIntroduction

Many further developments in the E90Introduction

VariantsFeatures of the MK60psiFeatures of the MK60E5System overview

MK60E5 - a further development of the MK60psiSensorsControl unitHydraulic control unitAdditional DSC functionsIntroductionSystem overviewFunctionsService information

Introduction

Cruise control with braking function (Dynamic Cruise Control DCC)System overview

FunctionsSystem overview

Active Cruise Control (ACC)IntroductionDifferences of "Active Cruise Control" option in E90 from option in E63/E64:Differences of 2nd generation ACC option from 1st generation ACC (e.g. E60 before 03/05):Customer benefits of 2nd generation ACC:

FunctionsSystem overview

IntroductionFunctionsPrevious functions of AL:New functions of AL in the E90:Yaw moment compensation

E90 Driving Dynamics Systems.pdf

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