Fully Integrated Transmission Control Controller Unit, Basic Function - GF27.60-P-2003A
Model all with transmission 725.0/1
Example illustration
Overview
This document contains information on:
- General
- Function
- Electronic and hydraulic transmission control
- Kickdown
- L imp-home mode
- Rotational speed sensor system
- Working pressure
- Lubrication pressure
- Shift pressure
General
The fully integrated transmission control unit controls the electromechanical hydraulic valves depending on the evaluated input signals. The electromechanical hydraulic valves determine the transmission ratio and working pressure.
The basic shift program includes upshift and downshift characteristics for all 9 gears, designed for:
- Empty vehicle
- Warm operating condition
- Smooth road
- Sea level
The shift programs are adapted by offsetting the characteristics, depending on:
- Load condition of vehicle
- Change in driving resistance
- Accelerator pedal movement
The fully integrated transmission control unit monitors and shifts depending on (among other things):
- Vehicle speed
- Selected drive range
- Accelerator pedal position
- Transmission mode selection
- Selected gear
Fully integrated transmission control controller unit
Function
Electronic and hydraulic transmission control
The electronic transmission control manages the gear selection, adaptation of the respective pressure and the torque that is to be transferred. The hydraulic elements in the fully integrated transmission control controller unit (1) manage the power supply control of the automatic transmission. The oil pump connected via the drive shaft and the electric auxiliary oil pump (4) supply the hydraulic elements (hydrodynamic torque converter, shift elements, hydraulic transmission control) with oil. The transmission control allows for a precise adaptation of the pressure to the respective operating status and to the engine output during the shift phase.
Kickdown
The kickdown function is activated from pedal travel > 90 % of the accelerator pedal sensor.
The kickdown signal is transmitted to the fully integrated transmission control unit by the combustion engine control unit.
So as to achieve maximum driving performance, the fully integrated transmission control unit actuates the solenoids in such a way that upshifting and downshifting take place at a higher engine speed. The forced downshift to the next lower gear is performed when transmission temperatures are too high and vehicle speed is too low.
Limp-home mode
If there is a defect on one of the solenoids, the corresponding gear is blocked and no longer engaged. The driver can engage the desired drive range P, R, N or D using the DIRECT SELECT selector lever. The driver can choose been forward and reverse travel, engage the park pawl or, when in neutral, interrupt the power flow between torque converter and automatic transmission.
The faults are stored in the fault memory. These can be read out using the XENTRY Diagnosis COM Kit. The diagnostics connection receives the transmission control diagnostic status from the fully integrated transmission control unit.
Manual shift operations that will result in impermissibly high or low engine speeds are not performed.
Rotational speed sensor system
Internal input speed rpm sensor
The internal input speed is recorded by an active sensor (difference Hall sensor with integrated magnet). The outer plate carrier is used as a passive sensor element for the internal input speed.
Turbine wheel rpm sensor
The turbine wheel speed is recorded by a passive sensor (difference Hall sensor). A sensor rotor is used as an active sensor element for the turbine speed. It is pressed onto the planet carrier of the planetary gear set P4.
Output shaft rpm sensor
The output speed is recorded by an active sensor with direction of rotation recognition (difference Hall sensor with integrated magnet). The external plate carrier is used as a passive sensor element for the output speed. It is welded to the output shaft.
In addition, the fully integrated transmission control controller unit (1) has rotational speed sensors that cannot be replaced individually.
Working pressure
The oil pressure produced by the primary pump is converted into working pressure by the working pressure regulating valve. The level of working pressure depends on the position of the regulating valve and therefore on its geometry.
The position of the working pressure regulating valve is influenced by the working pressure solenoid valve depending on the load and gear involved. All other oil pressures required for transmission control are derived from the working pressures.
Lubrication pressure
At the working pressure regulating valve excess oil is diverted to the lubrication pressure regulating valve and from there used in a regulated manner for lubrication and cooling of mechanical transmission parts and the torque converter. In addition, the oil pressure in the torque converter is limited via the lubrication pressure regulation.
Shift pressure
The shift pressure (oil pressure in the multiplate clutch or in the multidisk brake) is derived from the working pressure. The respective solenoid valve influences the position of the associated regulating valve. The position influences the oil pressure prevailing in the multidisk brake or in multiplate clutch. The shift pressure thus depends on the geometry of the respective regulating valve.
The shift rod regulation valves are proportional valves which enable the following valve positions:
- Open
- Intermediate position
- Closed
The regulation valves are actuated by pulse width modulated signals.
The gear control regulation valves are spring-loaded and also subjected to oil pressure which boosts the spring force. This provides a gentler pressure rise.
In the deenergized state, the gear control regulation valves are pressed back into their basic positions by the spring force.
| Additional base function | |||
| Gearshift system, basic function | GF27.60-P-1002B | ||
| Limp-home mode, basic function | GF27.60-P-9900B |