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Definition of Terms - Easytronic (M20 MTA) Programming transmission parameters. TECH 2 main menu: "Programming", submenu: "Program control unit To determine each gear position, the transmission moves through the S shift pattern. The neutral position is determined first. This is required so that the Easytronic control unit has a defined point in order to calibrate the other gears. After the reference point has been determined, all the other gears are engaged in turn and their gear geometry determined (end positions, rest positions, shift positions). Since the transmission may lock-up while the gear positions are being determined, ensure that the wheels can turn freely (use a lift platform). This enables the gear wheels to change position while a gear is being programmed, thus preventing them from locking-up. When programming the gears, each gear is engaged 3 times to ensure there is no more blocking. After the self-programming procedure has been completed, the control unit carries out a plausibility test to ensure that the programmed gears are within a certain tolerance range of the transmission and the MTA system. If the plausibility test produces a positive result, the programmed gearshift positions are stored in the EEPROM (flash memory). If not, a fault is recorded in the fault memory. The synchronisation thresholds are determined during normal driving operations. Default values are set initially for the synchronisation thresholds. Determining the contact point - TECH 2 main menu: "Programming" - submenu: "Program control unit The contact point is the position at which the pressure plate and the clutch plate come into contact with each other and transfer a small amount of torque (approx. 4 Nm ). The control unit is delivered with a pre-set contact point. This value will vary due to the different clutch and vehicle tolerances. Therefore, this parameter must be determined when the vehicle is commissioned. It is essential to determine the contact point before the clutch transfers higher levels of friction energy for the first time, so that premature damage to the clutch may be avoided. To prevent this, the control unit contains a test which ensures that the contact point is determined using TECH 2. If not, a fault code is stored and a quick contact point determination procedure is performed after each start. During this procedure, the transmission cannot perform any gearshifts. Even after this quick procedure has been carried out, it is not possible to shift all the gears. In this instance, the control unit only permits the neutral, 1st gear and reverse positions. This is necessary in order to prevent damage to the clutch or transmission. Once contact point determination has been carried out correctly, all gears are available again. Procedure for determining the contact point The procedure for determining the contact point takes approx. 20 seconds. At the beginning, the control unit uses a default value for the contact point. The procedure is as follows:
The contact point value stored in the control unit's EEPROM is a mean value of the various measurements. The quick procedure for determining the contact point works in the same way, but the clutch is not closed between the individual measuring procedures. Programming variants (programming the high-speed CAN bus). TECH 2 main menu: "Programming", submenu: "High-speed CAN bus configuration Depending on the vehicle specification the High-Speed CAN bus must be programmed. This process involves determining whether the vehicle is fitted with ABS. Incorrect programming is likely to result in malfunction and/or entries in the error log. Reading out/deleting the fault memory - TECH 2 main menu "Fault codes", submenus: "Fault codes sorted in order of priority / Delete fault codes Fault detection is integrated into the control unit software for more effective diagnosis of the entire system. As soon as a fault is detected, a certain fault code is inserted in the fault memory depending on the nature of the fault. An existing fault memory entry is retained in the memory until the fault memory is deleted. However, a distinction is made by the control unit as to whether a fault is currently still present or is no longer present. In addition, fault codes are further subdivided with the aid of a symptom code in order to obtain more precise information about the individual faults. If a fault is detected, the control unit reacts with specific strategies and fault displays. Further information about fault codes, causes of faults and measures for fault rectification are to be found in the test instructions. Creep The Easytronic system features a creep function. The creep function enables the vehicle to pull away gently at idle speed, with a gear engaged and the brake off. The clutch is part-closed in the process. This makes it easier to manoeuvre and park the vehicle. If the clutch temperature is high, the creep torque is increased using a specified method. Energy Entry into the Clutch (Slip) Whilst the vehicle is operating, energy is brought into the clutch during slip. The difference in speed occurring between the engine output speed and the transmission input speed when transferring torque is designated slip. The greater the energy entering, the greater the heating of the individual components of the clutch. The individual components of the clutch have specific temperature limits, above which irreversible changes occur and therefore its function and characteristics are impaired. Clutch protection function To prevent the clutch from overheating, a protection function is implemented in the software. This monitors the clutch temperature and the duration of slip. The control unit takes this situation into account and implements a correction to ensure torque is transferred. Friction Coefficient The friction coefficient used in the Easytronic control system is not the same as the physical friction coefficient at the clutch plate lining. The Easytronic friction coefficient is a software operand which is used to adapt the actuating torque curve stored in the software to the actual curve. The Easytronic friction coefficient is a factor which acts on the clutch torque (friction coefficient adaptation). The friction coefficient includes all the variables which change the clutch torque transfer behaviour as a function of the actuator travel. These include the transfer distance, thermal effects on the clutch, the physical friction coefficient and the friction radius. Adaptation Modification of the programmed data during vehicle operation is referred to as adaptation. The curves and transmission geometry data stored in the control unit are thereby continually being adapted to the current conditions. Friction Coefficient Adaptation The friction coefficient is adapted in the vehicle. To do this, the engine torque signal and the actuator travel are evaluated during conditions of slip (e.g.when driving off). The Easytronic control system uses the friction coefficient factor to modify the clutch torque so that the nominal actuating torque curve approximately matches the actual curve. Contact Point Adaptation Contact point adaptation is performed to balance out shifts in the torque curve caused by thermal conditions and/or wear. Contact point adaptation is performed when the vehicle is stationary, after starting and with the transmission in neutral. Snuffle Bore The snuffle bore is a small aperture in the master cylinder. It permits fluid compensation and therefore length compensation in the release system (snuffling) via a compensation tank which serves as a pressure reservoir. This process, which is also designated compensation, is necessary to compensate for changes in the volume of liquid caused by temperature fluctuations or reduction in the volume of fluid because of loss of fluid or wear. |
