Transmission Control

Transmission control 9HP

Due to reasons of cost efficiency and installation space optimization, ZF engineers did not use a fully-integrated mechatronics module for all sensors, actuators, and the electronic control unit (ECU) in the 9 HP. Instead, the ECU is installed separately from the now significantly smaller hydraulic control unit (HCU), namely on the upper side of the transmission housing. The sensors can be found inside the transmission, vehicle-side signals are connected directly to the male plug of the ECU.

In case of the 9HP, ZF develops and produces the complete ECU itself for the first time. A powerful embedded flash controller can realize complex control algorithms. Its calculation performance is comparable to the controller used in the 8-speed automatic transmission and can be increased by approx. 30 percent on demand. Thus, the 9HP will also be equipped for even more comprehensive software functions in the future. The layout of the ECU printed circuit board has been designed so that the different hardware requirements of the OEMs can be met without any problems.

As a construction kit, the ECU is suitable both for a pure shift-by-wire actuation (electronic shift system) and for a shift-by-wire/park-by-cable actuation (electronic/manual shift system):

In order to meet the increased requirements for driveline efficiency, the HCU incl. the actuators was designed and built for minimal hydraulic losses. Thus, the leakage losses in the control unit could be reduced to a minimum. For the dog clutch actuation, a fast and at the same time resource-saving actuation was the central design criterion. ZF Friedrichshafen AG uses its expertise in the area of application-specific software development: The ATSYS shifting sequence control contains all clutch controls, adaptation functions, and transmission protection functions while the ASIS driving strategy ensures that the optimal gear is selected for each driving situation - unnoticed by the driver. In general, the transmission software is currently a central component of development. It determines and optimizes nearly all functions which can be noticed by the customer. The increasing memory requirements of the transmission control thus becomes apparent in the different automatic transmission generations by ZF.