|The two-mode hybrid system uses different pairings of two electric motors to support low-speed and high-speed driving.|
The BMW Group, DaimlerChrysler and General Motors today formed an alliance of equals for the joint development of hybrid drive systems. The three global automakers are cooperating in order to pool their expertise for the accelerated and efficient development of hybrid drive systems.
The objective is to develop a two-mode hybrid drive system that reduces fuel consumption while still maintaining what each automaker believes necessary in terms of individual vehicle performance and capability.
While the base two-mode hybrid design will be common to the three, each company will individually integrate the hybrid system into the design and manufacturing of vehicles in accordance with their brand-specific requirements.
The participation of the BMW Group has allowed us to gain another expert partner for the development of this advanced two-mode hybrid system. This cooperation paves the way for extensive hybrid collaboration among the three companies. We also continue to discuss additional partners for this alliance.—Tom Stephens, Group Vice President at GM Powertrain
By pooling the development expertise of the three automakers—BMW Group, DaimlerChrysler and General Motors—we are making it possible for all companies to bring to market appealing vehicles with convincing performance, comfort and environmental features for the benefit of our customers.—Dr. Thomas Weber, DaimlerChrysler Board of Management member responsible for Research and Technology as well as Mercedes Development
The creation of a shared technology platform for hybrid drives will allow us to more quickly integrate the best technologies on the market and will therefore exploit and strengthen the innovative potential of all participating companies. Because the technologies will be adapted to the individual vehicle models, the participating brands will retain their distinctive characters.—Prof. Burkhard Göschel, Board of Management member for Development and Procurement at BMW AG
A new GM, DaimlerChrysler and BMW Hybrid Development Center in Troy, Michigan, will develop the overall modular system and the individual components: electric motors, high-performance electronics, wiring, safety systems, energy management, and hybrid system control units. In addition, the Hybrid Development Center will be responsible for system integration and project management.
The sharing of components and production facilities, and the collaborative relationship with suppliers, will enable the alliance partners to achieve significant economies of scale and associated cost advantages.
The two-mode system proposed earlier by GM and DaimlerChrysler (earlier post) is, in essence, an electrically variable transmission with two hybrid drive modes provided by a variable pairing of two electric motors.
The first mode (input split mode) is for low-speed, stop-and-start, in-city driving. In this mode, the system can operate just with the engine, just with the motor, or with any combination of the two. In this mode, one motor acts as a generator, while the other provides drive (motor) power.
The second (compound split mode) is for highway driving—an area in which other single-mode hybrids have not performed as well as expected. In this mode, both motors, managed by the control unit, selectively operate in motoring or generating modes depending upon the vehicle speed and working in conjunction with the other engine technologies, such as Displacement on Demand. The electric motors not only regulate the power flow, but also aid in extending DoD operation well beyond what is capable without hybrid assist.
GM introduced two concept vehicles, an SUV and a diesel sedan, based on the two-mode hybrid at the North American International Auto Show in Detroit this past January. (Earlier post.) The goal, according to Stephens, is “guilt-free performance.”
“Guilt-free” motivation may now be displaced by “affordable”—GM intends to deploy the system in late 2007 in its Chevrolet Tahoe and GMC Yukon full-size sport utility vehicles. Chrysler will follow with a hybrid version of its Dodge Durango full-size SUV among a range of hybrids.
Daimler’s Mercedes brand is also working on an application for rear-wheel-drive passenger cars.
GM and DaimlerChrysler announced their intention to partner on the two-mode development in December 2004, and signed binding, definitive agreements on 22 August 2005. BMW Group today signed a memorandum of understanding with the intent to enter into a definitive agreement with GM and DaimlerChrysler later this year.