· Linked thrust belts provide up to 450 Newton meters torque for continuously variable transmissions

To meet the rising demands for comfort as well as for reduced consumption and CO2 emissions, and to comply with increasingly strict emissions requirements, Bosch is pushing ahead with the development of electronic transmission control. As a systems supplier and the market leader, the company's range of products includes electronic and hydraulic components for controlling automatic step transmission, continuously variable transmission (CVT), twin-clutch transmission, and automated shift transmission. It also includes control units and actuators for distribution gearing and differential locks for four-wheel-drive vehicles. Bosch has been developing and supplying transmission controls for more than 25 years. In the U.S. and Japan, demand for automatic transmissions remains high. In Europe, the share of vehicles equipped with twin-clutch transmissions is growing.

Innovative: second-generation transmission control units
The second generation of Bosch transmission control units contribute toward innovative transmission design aimed at reducing fuel consumption and emissions. They allow coordinated drivetrain control, which combines transmission control and engine management, and which is suitable for automatic transmissions, double-clutch transmissions, and continuously variable transmissions. The TCU has a 32-bit microcontroller and a new, modular software architecture. The control unit is designed to withstand temperatures between minus 40 and plus 150 degrees Celsius, and can be installed in the transmission. In the transmission electrohydraulic control module, or TEHCM, transmission control, pressure regulator, solenoid valves, and sensors are integrated into a single component in order to save installation space and handling costs. As most plug-in connectors and cables are no longer needed, it is lighter in weight and offers maximum reliability. The module is also robust, allowing it to be installed directly in the transmission. A current example of innovative Bosch transmission control is its module for eight-gear automatic transmissions, which has been consistently designed for more dynamic gear shifts and reduced fuel consumption.

Up to 5 percent less fuel consumption: with CVT
Continuously variable transmissions (CVT) are suitable for any type of vehicle, whether small car or SUV, diesel, gasoline, or hybrid. The transmissible torque and efficiency of this innovative transmission have been continuously improved. If modern CVTs are used in combination with downsized gasoline and diesel direct injection engines, then even better fuel consumption and CO2 emissions can be achieved. The core component of a continuously variable transmission is the linked metal thrust belt made by Bosch. This runs in the groove between two axially adjustable taper-disk sections and changes the transmission ratio according to engine speed. Up to 450 Newton meters of engine torque can be transmitted in this way. In the New European Driving Cycle (NEDC) and with the same vehicle configuration, fuel consumption is up to five percent lower than for a drivetrain with manual transmission. The reason for this saving is that the optimum transmission ratio is nearly always used. This means that the engine is nearly always able to run in the most economical speed range. For drivers, reduced fuel consumption is not the only benefit of this technology. Because the transmission ratio can be infinitely varied without traction loss, CVT transmissions are characterized by excellent comfort and dynamic acceleration. Carmakers across the globe currently offer roughly 100 models with this transmission technology, and more than 90 of them are equipped with Bosch CVT.

The Bosch Group is a leading global supplier of technology and services. In the areas of automotive and industrial technology, consumer goods, and building technology, some 275,000 associates generated sales of 38.2 billion euros in fiscal 2009. The Bosch Group comprises Robert Bosch GmbH and its more than 300 subsidiaries and regional companies in over 60 countries. If its sales and service partners are included, then Bosch is represented in roughly 150 countries. This worldwide development, manufacturing, and sales network is the foundation for growth. Each year, Bosch spends more than 3.5 billion euros for research and development, and applies for some 3,800 patents worldwide. With all its products and services, Bosch enhances the quality of life by providing solutions which are both innovative and beneficial. The company was set up in Stuttgart in 1886 by Robert Bosch (1861-1942) as “Workshop for Precision Mechanics and Electrical Engineering.” The special ownership structure of Robert Bosch GmbH guarantees the entrepreneurial freedom of the Bosch Group, making it possible for the company to plan over the long term and to undertake significant up-front investments in the safeguarding of its future. Ninety-two percent of the share capital of Robert Bosch GmbH is held by Robert Bosch Stiftung GmbH, a charitable foundation. The majority of voting rights are held by Robert Bosch Industrietreuhand KG, an industrial trust. The entrepreneurial ownership functions are carried out by the trust. The remaining shares are held by the Bosch family and by Robert Bosch GmbH. Additional information can be accessed at www.bosch.com.

PI6746 - September 2009