Dual Clutch Transmissions #
Controlling dual-clutch transmissions with HTG tuning GCU Gearbox Control Unit user has couple different possible methods how to perform a launch.
- LAUNCH control strategy
- Clutch-By-Wire drop
Hydraulic transmissions #
Controlling hydraulic TCC transmissions with HTG GCU Gearbox Control Unit user has couple different possible methods how to perform a launch.
- TRANSBRAKE strategy
- Clutch-By-Wire drop
Clutch-By-Wire drop #
CbW drop is the simplest method how to launch. Regardless of the transmission type that is CbW compatible is it possible to fully disengage power delivery to the drivetrain by disengaging leading clutch. GCU has configurable CbW input, which is a modifier of commanded clutch pressure. 100% CbW means no change in clutch pressure, while 0% means full pressure reduction – drivetrain disengagement. To activate Launch Control GEAR ratios have to be filled in as well as vehicle speed has to be zero (stationary).
With CbW fully pressed (value 0%) user can rev engine as high as desired, and re-engage in any moment.
Enable launch control in ECU, and with fully pressed CbW build torque; launch in desired moment. Set ECU to disengage Launch control above X km/h VSS (can be output from GCU).
LAUNCH control strategy (for dual clutches): #
Launch control (v1) strategy in GCU activates second set of take-up pressure table that can be fully adjusted by user in means of output values (pressure) as well as axes (X and Y). It can be activated by any type of input that is assigned to that certain function with result YES. GCU streams „launch control active” flag while this mode is engaged.
Implementation idea A:
Assign input to the GCU that will activate launch control mode. Same input COULD also trigger ECU launch control if it is needed (but has to remain ON when it releases RPMs so GCU can remain in Launch State). While activated GCU streams flag. Knowing what RPM are set as cut-off RPM in ECU, adjust LAUNCH control pressure in a way that up to ECU cut-off RPM pressure remains low (does not apply significant torque to the wheels), but high enough to prefill clutches and cancel loose play in the drivetrain.
[!!! CAUTION !!!]
Be aware that too high LAUNCH control pressure while stationary with high engine torque may lead to overheating clutch plates so fine tune pressures wisely and do not remain in that state for too long!!!
When ready to launch release engine RPMs so they can go up (still having GCU in Launch Mode), GCU should now enter table cells just above cutoff RPM, which should be high enough to firmly clamp the clutches.
GCU allows using TB strategy if following conditions are fulfilled: Vehicle speed is 0, Input switch is YES and GCU in Manual mode in gear 1 or 2.
TB fully locks the transmission, so only slip occurs at torque converter. Slip RPMs are directly dependent on converter stall.
- Dual Clutch Launch control (CL)
1.1.2 firmware enabled DC CL launch control that allows user defined pre-load on the drivetrain