General Motors is gearing up to launch a new affordable hybrid system that will deliver a good fuel economy savings and a real payback for consumers. Saturn will be the first to debut the belt alternator starter hybrid system in mid-2006, when it introduces the 2007 Vue Green Line.

The GM belt alternator starter hybrid is one of three innovative hybrid systems that GM plans to introduce on up to 12 models, providing consumers a broad portfolio of hybrid systems that will vary in fuel savings and cost.

GM launched the world’s first hybrid pickup trucks in 2004, the Chevrolet Silverado and GMC Sierra. Retail availability of these full-size trucks with GM’s parallel-hybrid system expands nationwide beginning with the 2006 model year after initially being sold in six states.

GM also announced it is developing an all-new two-mode full hybrid system that is uniquely compact and scalable. This new two-mode full hybrid will first be marketed in GM’s new Chevrolet Tahoe and GMC Yukon full-size SUVs in 2007. The system is based on GM’s successful diesel-electric hybrid propulsion system for transit buses, 364 of which are in service in 25 cities in the U.S. and Canada .

GM’s belt alternator starter hybrid combines sophisticated controls with a precision electric motor/generator mated to the engine.

Among the many advantages of the GM belt alternator starter hybrid is its flexibility. It can be applied to multiple engines with minimal change to the engine or transmission.

In the Saturn Vue Green Line, the system will be mated with GM’s state-of-the-art 2.4-liter variable valve timing (VVT) Ecotec engine and Hydra-Matic 4T45-E electronically controlled overdrive transaxle.

GM engineers developed the belt alternator starter hybrid to deliver improved fuel economy by performing the following functions:

   * Shuts off the engine when the vehicle is brought to a stop to minimize engine idling
   * Restarts the engine promptly when the brake pedal is released
   * Enables early fuel cutoff to the engine during vehicle deceleration
   * Captures vehicle kinetic energy during deceleration to help charge the advanced nickel metal hydride hybrid battery (regenerative braking)
   * Performs intelligent battery charging by opportunistically charging when it’s most efficient

The belt alternator starter hybrid also will provide an electric power assist during acceleration when needed. During a wide-open throttle or aggressive passing maneuver, the system improves vehicle launch and acceleration feel by assisting the engine to achieve maximum power.

The system is designed to automatically maintain accessory functionality and passenger comfort when the engine is stopped so that hybrid operation is transparent to the driver and passengers.

The belt alternator starter hybrid consists of six major components:

   * A precision electric motor/generator unit
   * Engine coolant-cooled power electronics that control the motor/generator unit and provide 12-volt vehicle accessory power
   * An advanced, nickel metal hydride hybrid battery pack capable of delivering and receiving more than 10kW of peak power
   * An engine control module that includes sophisticated Hybrid Supervisory Software to manage both engine and hybrid system operation
   * A new engine accessory drive with dual tensioner assembly and aramid cord belt that enables reliable transfer of both motoring and generating torque
   * The hybrid-enabled 4T45-E electronically controlled overdrive transaxle that includes an auxiliary oil pump and unique hybrid controls to ensure seamless hybrid operation.

GM’s belt alternator starter hybrid operates in motoring or generating mode.

In the motoring mode, the belt alternator starter hybrid is used to quickly restart the engine upon brake pedal release and to provide momentary acceleration assist as needed. To perform these functions, the advanced nickel metal hydride hybrid battery converts its stored chemical energy into direct current (DC) electrical energy. The hybrid’s power electronics then convert the DC electrical energy to three-phase alternating current (AC) to run the motor/generator unit as a motor. Vehicle accessory power (12V) is also generated in this mode.

In the generating mode, the belt alternator starter hybrid is used to provide both 12V vehicle accessory power and power to recharge the hybrid battery. To perform these functions, the engine is used to power the motor/generator unit, which then provides a three-phase electrical output. In this mode, the energy required to drive the engine may come from either gasoline when accelerating or the kinetic energy of the moving vehicle when decelerating with the fuel cut off. The three-phase AC electrical output of the motor/generator is then converted to DC electrical outputs by the power electronics that are, in turn, used to efficiently charge both the hybrid and vehicle accessory batteries.

GM’s hybrid strategy is part of GM’s larger overall advanced propulsion technology strategy, which is focused on introducing new technologies to improve the internal combustion engine and transmissions to further reduce vehicle emissions and increase fuel economy.