GF27.10-P-0001CWQ Automatic Transmission (AT), Function

GF27.10-P-0001CWQ Automatic transmission (AT), function
- Transmission 722.9

Transmission 722.9 is an electronically controlled automatic transmission with 7 forward gears and 2 reverse gears. All the transmission functions and transmission components for this automatic transmission are combined in one assembly module. The interfaces to the wiring harness have been minimized by the integration of the electrohydraulic controller unit in transmission 722.9. The electrohydraulic controller unit is assembled under the transmission housing and is constantly flushed by transmission oil and amongst others also cooled as a result.

Transmission 722.9 can be roughly divided into the following component groups:
^ the torque converter with torsional damper and torque converter lockup clutch.
^ The oil pump for generating the necessary oil pressure and for reliable lubrication of the actuators and bearing points.
^ The transmission housing with mechanical transmission components and electrohydraulic controller unit. The transmission housing is made of a light alloy.
^ The electrohydraulic controller unit, consisting of the fully integrated transmission control controller unit (Y3/8), the valve housing and valve body.

^ The mechanical transmission components, consisting of a Ravigneaux gear set, single planetary gear set at the front, the single planetary gear set at the rear and the park pawl. Furthermore the multidisk clutch K1, the multidisk clutch K2, the multidisk clutch K3, the multidisk brake B1, the multidisk brake B2, the multidisk brake B3 and the multidisk brake BR. Single-sided disks are used on multidisk clutch K1, on multidisk clutch K2 and on multidisk clutch K3. Single-sided disks are also used on multidisk brake B1 and on multidisk brake B3. On this type of lamella the friction lining is only applied on one side. Among other things, this improves heat distribution in the disk pack, the design of the disk pack is more compact, the load-bearing capacity is increased and the mass is reduced. On the multidisk brake B2 and the multidisk brake BR coated lamella continue to be used on both sides.

The following information are taken into account when shifting the drive positions:
^ Vehicle speed
^ Vehicle load
^ Driving resistance
^ Position and operating speed of accelerator pedal
^ Selected gear range and engaged gear
^ Selected transmission mode
^ Oil temperature and other information about the status of the transmission
^ Further signals which are available via the Controller Area Network (data bus/CAN bus) (CAN)

A data exchange takes place with the following control units and controls via CAN:
^ Instrument cluster (A1), via the chassis CAN
^ Electronic selector lever module control unit (N15/5), via the drive train CAN

^ CDI control unit (N3/9), via drive train CAN
^ Electronic Stability Program control unit (N30/4), via the chassis CAN
^ Electronic ignition lock control unit (N73), via the chassis CAN
^ Steering column module control unit (N80), via the chassis CAN
^ Front SAM control unit with fuse and relay module (N10/1), via the chassis CAN

The CDI control unit is the interface between the drive train CAN and the chassis CAN, the front SAM control unit with fuse and relay module is amongst others the interface between the chassis CAN, the interior CAN and the Diagnostic CAN.

This involves the processing of the following data from other systems:

Electronic selector lever module control unit
^ Selector lever position

Electronic Stability Program control unit (N30/4)
^ Wheel speeds and direction of rotation, substitute values in the event of failure of the output shaft rpm sensor (Y3/8n3)
^ Adjusted brake torque, change in shift strategy, brake the vehicle, fully integrated transmission control (VGS) shifts down sooner
^ Vehicle lateral acceleration at center of gravity, adaptation of shift strategy, detection of dynamic driving style
^ Cruise control regulates, a special shift strategy for tempomat mode is stored in the fully integrated transmission control unit
^ ESP request shift into "N" (neutral), power flow interruption, transmission/rear axle
^ BAS release switch (A7/7s1), change of shift strategy, brake the vehicle, the fully integrated transmission control shift down sooner

CDI control unit
^ Engine torque
^ Emergency operation of the common rail diesel injection, the pedal value is limited to approx. 20 %, the driveability of the vehicle is assured
^ Engine coolant temperature is used as a substitute value in the event of failure of the transmission oil temperature sensor (Y3/8s2)
^ Kickdown
^ Pedal value
^ Engine oil temperature, as from a certain value shift limitation is not active
^ Requirement torque for Electronic Stability Program (Electronic-Stability-Program) (ESP), torque reduction or torque increase taking into account directional stability and road adhesion

^ Engine speed, for slip calculation of the torque converter lockup clutch and for the start of pressure calculation by the fully integrated transmission control unit
^ Engine idle specified speed for the actuation of the torque converter lockup clutch

Electronic ignition switch control unit
^ Enable of stage 3 drive authorization system (DAS 3)
^ Request of Key-P function
^ Circuit 50, influencing fault memory

Steering column module control unit
^ Signal from the steering wheel downshift button (S110/1), with code (428) Steering wheel shift buttons
^ Signal from the steering wheel upshift button (S111/1), with code (428) Steering wheel shift buttons

Front SAM control unit with fuse and relay module
^ Diagnosis

Information which is output to other systems:

Instrument cluster
^ Position of automatic transmission mode button (S16/12) and programmed shift range for the gear indicator (A1p12)
^ Transmission mode selection for the transmission mode display (A1p16)

Electronic selector lever module control unit
^ Selector lever position
^ Actual position of the transmission
^ Specified position of selector range lever

Electronic Stability Program control unit
^ Wheel torque factor, overall gear ratio
^ Transmission variant, recognition of basic variants, difference in gear ratios
^ Actual gear engaged and target gear, i.e. engaged gear, gear to be engaged, can be shown via STAR DIAGNOSIS

CDI control unit
^ Engine torque requests, engine intervention when shifting
^ Limp-home mode of fully integrated transmission control (VGS)
^ Starter lockout release in gear selector switch position "P", "N"
^ Transmission variant, recognition of basic variants, difference in gear ratios
^ Actual gear engaged and target gear, i.e. engaged gear, gear to be engaged, can be shown via STAR DIAGNOSIS
^ Status of torque converter lockup clutch

Front SAM control unit with fuse and relay module
^ Diagnosis