Function requirements for shift operation
Circuit 15 ON
Shift operation, general
The fully integrated transmission control (VGS) electric controller unit (N15/11) converts the electrical signals issued by the fully integrated transmission control (VGS) control unit (N15/11n4) into hydraulic signals. The selector lever positions P, R, N, D of the DIRECT SELECT selector lever (S16/13) are transmitted via the steering column tube module (MRM) control unit (N80) and the chassis CAN (CAN E) to the CDI control unit (N3/33) (with engine 651) or to the ME-SFI control unit (N3/34) (with engine 274). This transmits the information via the drive train CAN (CAN C) to the intelligent servo module (ISM) for DIRECT SELECT control unit (A80) and to the fully integrated transmission control (VGS) control unit.
The intelligent servo module (ISM) for DIRECT SELECT control unit changes the position of the range selection shaft, which is mechanically forwarded to the selection range sensor (N15/11s1).
Although the shift range can be changed in the forward gears while driving, the fully integrated transmission control (VGS) control unit prevents a shift operation if the engine speed is too high or too low.
The intelligent servo module (ISM) for DIRECT SELECT control unit sends the status of the range selection position via the drive train CAN to the CDI control unit or the ME-SFI control unit and to the fully integrated transmission control (VGS) control unit. In addition, the fully integrated transmission control (VGS) control unit sends the received status via the drive train CAN to the CDI control unit or the ME-SFI control unit.
The fully integrated transmission control (VGS) control unit and the intelligent servo module (ISM) for DIRECT SELECT control unit read in the status of circuit 15 in order to check the function requirements. The circuit 15 ON status is transmitted by the electronic ignition lock (EZS) control unit (N73) via the chassis CAN, the CDI control unit or the ME-SFI control unit and the drive train CAN.
The CDI control unit or ME-SFI control unit sends the signals from the operational drive train and running engine and the status of the engine management system via the drive train CAN to the fully integrated transmission control (VGS) control unit. In addition, the CDI control unit or the ME-SFI control unit transmits the signal for the running engine via the drive train CAN to the intelligent servo module (ISM) for DIRECT SELECT control unit.
The drive authorization system enable signal is sent by the electronic ignition lock (EZS) control unit via the chassis CAN, the CDI control unit or ME-SFI control unit and the drive train CAN to the fully integrated transmission control (VGS) control unit and to the intelligent servo module (ISM) for DIRECT SELECT control unit.
The following control solenoid valves are actuated by the fully integrated transmission control (VGS) control unit:
Working pressure control solenoid valve (N15/11y1)
K1 clutch control solenoid valve (N15/11y2)
K2 clutch control solenoid valve (N15/11y3)
K3 clutch control solenoid valve (N15/11y4)
B1 multidisk brake control solenoid valve (N15/11y5)
B2 multidisk brake control solenoid valve (N15/11y6)
B3 multidisk brake control solenoid valve (N15/11y7)
Torque converter lockup clutch control solenoid valve (N15/11y8)
The signals of the following components are processed by the fully integrated transmission control (VGS) control unit:
Turbine wheel rpm sensor (N15/11n1)
Rpm sensor for internal input speed (N15/11n2)
Output shaft rpm sensor (N15/11n3)
Selection range sensor (N15/11s1)
Transmission oil temperature sensor (N15/11s2) (integrated into fully integrated transmission control (VGS) control unit)
Messages and displays in instrument cluster (IC) control unit (A1/1)
The fully integrated transmission control (VGS) control unit sends the information regarding messages and displays in the instrument cluster (IC) control unit:
Via the drive train CAN, the CDI control unit or the ME-SFI control unit and the chassis CAN to the instrument cluster (IC) control unit (model 447.6/7)
Via the drive train CAN, the CDI control unit, the chassis CAN, the gateway for the user interface CAN (N93/4) and the user interface CAN (CAN HMI) to the instrument cluster (IC) control unit (model 447.8)
The instrument cluster (IC) control unit notifies the driver of the currently engaged gear range by means of the gear indicator (A1/1p12) and the transmission mode display (A1/1p16) in the multifunction display (A1/1p13).
Function sequence for shift operation
The function sequence is described in the following steps:
Function sequence for gear limitation and shifting into optimum gear
Function sequence for shifting from 1st to 2nd gear
Function sequence for gear limitation and shifting into optimum gear
The fully integrated transmission control (VGS) control unit sends the following signals via the drive train CAN to the CDI control unit or the ME-SFI control unit:
Information from the transmission control
Engine torque request
Shift point request
By pressing the steering wheel downshift button (S110/1) or the steering wheel upshift button (S111/1) the driver can select the following functions:
Pressing the steering wheel downshift button once activates the gear limitation function (if the engine speed permits, the transmission shifts down one gear)
By pressing and holding down the steering wheel downshift button, the "shift to optimum gear" function is selected (the gear which enables the maximum acceleration of the vehicle is selected)
Pressing the steering wheel upshift button once with gear limitation selected increases gearshift limitation by one gear (e.g. from 3rd gear to 4th gear)
Pressing the steering wheel upshift button once in gear range D sends an upshift request to the automatic transmission (the automatic transmission shifts up to match the driving situation)
Pressing and holding down the steering wheel upshift button cancels the gear limitation function completely (shift to gear range D)
The signals of the steering wheel downshift button and the steering wheel upshift button are read in by the steering wheel electronics (N135) and sent to the fully integrated transmission control (VGS) control unit over the steering LIN (LIN E1), the steering column tube module (MRM) control unit, the chassis CAN, the CDI control unit or ME-SFI control unit and the drive train CAN.
Transmission 722.9 in model 447.6/7
The transmission mode can be influenced by the driver using the transmission mode button (N72/1s6), which is located in the upper control panel (UCP) control unit (N72/1). The status is sent via the upper control panel (UCP) control unit, the battery sensor LIN (LIN B15), the signal acquisition and actuation module (SAM) control unit (N10/1), the interior CAN (CAN B), the electronic ignition lock (EZS) control unit and the chassis CAN to the CDI control unit or ME-SFI control unit. This transmits the status via the drive train CAN to the fully integrated transmission control (VGS) control unit.
Transmission 722.9 in model 447.8
The transmission mode can be influenced by the driver using the AGILITY SELECT switch (A40/1s1), which is located in the area of the center console. The status is sent via the left lower control panel (LCPL) control unit (A40/1), the telephone keypad LIN (LIN A2), the central operating unit (COU) control unit (A40), the telematics CAN (CAN A), the radio (Audio/COMAND) (N87/6), the user interface CAN (CAN HMI), the gateway for the user interface CAN and the chassis CAN to the CDI control unit. This transmits the status via the drive train CAN to the fully integrated transmission control (VGS) control unit.
Depending on the transmission mode selected, different gear ranges (for shifting at low or high engine speed) and drive torques adapted to the operating conditions are available when moving off.
The reverse gear, park position and the neutral position can only be engaged through the intelligent servo module (ISM) for DIRECT SELECT control unit.
Function sequence for shifting from 1st to 2nd gear
Multidisk brake B2, multidisk brake B3 and multidisk clutch K3 are engaged in 1st gear. When shifting from 1st gear to 2nd gear, multidisk brake B3 is disengaged and multidisk brake B1 is engaged.
The shift operation is started by the fully integrated transmission control (VGS) control unit. In the process the multidisk brake B1 is filled with oil and the pressure in the multidisk brake B1 is continuously increased. Simultaneously the pressure in multidisk brake B3 is reduced.
This involves a flowing transition. When the 2nd gear torque is reached, the engine speed must be adapted to the 2nd gear level (elevation phase).
This speed adjustment is achieved by the pressure in the multidisk brake B1 being increased and, if necessary, engine torque being reduced through the CDI control unit or ME-SFI control unit.
A forced downshift occurs at excessively low rpm and a forced upshift occurs at an excessively high rpm.
When the vehicle is stationary the transmission automatically shifts into 1st gear. It is possible to start off both in 1st gear and 2nd gear.
Referenced documents
- gf2710s9992tra Overview of system components of automatic transmission (AT)