- 1 -
February 2006
GM goes Hybrid: Three Systems for a Range of Vehicles on Way to Market
- Chevrolet Tahoe Hybrid: Two-mode hybrid, 25 percent economy improvement
Saturn Vue Green Line Hybrid: Great fuel economy, low cost
Geneva. GM launched the world’s first hybrid pickup, the Chevrolet Silverado, trucks in 2004, with retail availability expanding in 2006. A couple of weeks ago, at the Detroit Motor Show, Saturn unveiled the production version of the 2007 Vue Green Line Hybrid, the first GM vehicle powered by a new, more affordable hybrid system. The Vue Green Line delivers an estimated 20 percent improvement in fuel economy, depending on driving conditions.
GM also will introduce an all-new, two-mode hybrid system that is uniquely compact and scalable to vehicles of all sizes. After its premiere in Detroit it is presented for the first time in Europe at the 2006 Geneva Show. This new system will debut on theUS market in GM’s new, full-size Chevy Tahoe and GMC Yukon SUVs in 2007. Next year, the GM transmission plant in White Mash, Maryland (USA) will start production of the world’s first transmission for rear-wheel-driven vehicles. GM will launch a range of hybrids, providing customers with several levels of fuel economy savings at different price points on vehicles ranging from cars to full-size SUVs. It is a strategy that leverages the technology to produce the greatest overall benefit over a wide range of products in GM’s portfolio.
GM has applied its two-mode hybrid system for the first time to transit buses. More than 380 of them, featuring this pro-environmental, fuel-saving GM hybrid propulsion, are currently operating in a total of 29 US cities and in YosemiteNational Park. In WashingtonD.C. the first of 50 hybrid-powered buses is getting into service. In 2006, deliveries of a total of 216 GM hybrid-powered buses in six US cities are planned.
Chevrolet Tahoe Two-mode Hybrid
The Chevrolet Tahoe Two-mode Hybrid combines the functionality and comfort of a full-size SUV with a two-mode full hybrid system that optimizes fuel efficiency in both city and highway driving. The Vortec V-8 powered Tahoe Two-mode Hybrid is expected to deliver a composite fuel efficiency improvement of 25 percent when combined with Active Fuel Management™ cylinder deactivation technology.
“The Tahoe Two-mode Hybrid delivers on GM’s commitment to apply advanced technologies where we will realize the most fuel savings,” said Tom Stephens, Group Vice President, GM Powertrain. The Tahoe Hybrid will go on sale in the US next year as a 2008 model, along with the GMC Yukon Two-mode Hybrid. Pricing and production volumes have not been announced.
“We took the brand-new, next-generation full-size truck platform, which already had segment-leading fuel economy and world-class aerodynamics, and took it to the next level,” said Mark Cieslak, Assistant Vehicle Chief Engineer for the Chevy Tahoe Two-mode Hybrid. “This was in addition to maintaining important performance attributes of full-size trucks, such as off-road capability, towing at 2,700kilograms, great accelerationtimes and much more.”
GM, BMW and DaimlerChrysler are co-developing the two-mode full hybrid system that will leverage automatic transmission technology and electronic controls in an integrated, powerful and compact system that can be used with both gas and diesel engines.
GM’s two-mode full hybrid system in transit buses has been established as the starting point for the GM-BMW-DaimlerChrysler collaboration. The design integrates proven automatic transmission technology with a patented hybrid-electric drive system to deliver the world’s first two-mode full hybrid. The two-mode is patented hybrid technology with two modes optimized for city and highway driving.
In the first mode, at low speed and light loads, the vehicle can operate in three ways: electric power only, engine power only or in any combination of engine and electric power. When operating with electric power only, it provides all the fuel savings benefits of a full hybrid system. Leaving the engine shut off for extended periods of time and moving under electric power at low speed is key to reducing fuel consumption in heavy stop and go traffic.
The second mode is used primarily at highway speeds. In addition to electric assist, the second mode provides full eight-cylinder engine power when conditions demand it, such as when passing, pulling a trailer or climbing a steep grade. It also integrates sophisticated electronic controls, such as Active Fuel Management, cam phasing, and late-intake valve closure, allowing even more efficient engine operation.
Two-mode system innovations allow for more compact packaging because its compact and powerful electric motors are designed to fit within the approximate space of a conventional automatic transmission – an efficiency advantage compared with today’s typical single-mode systems that rely on much larger electric motors.A sophisticated controller determines when the vehicle should operate in either mode of the two-mode drive system. Input from the controller determines the necessary torque for the driving conditions and sends a corresponding command to the engine and electric motors. The engine and electric motors transfer torque to a series of gears in the transmission, which multiply torque similar to a conventional automatic transmission to propel the vehicle. Shifts between the two modes are synchronous, which means no engine speed changes are necessary for the mode shift to occur, resulting in ultra smooth accelerations.
The 300-volt battery pack provides electric power for the system, and while it is larger than a typical automotive battery, it is designed to fit in the vehicle without compromising passenger space. Special converters located under the vehicle’s hood convert the motors’ AC output to DC current and power conventional 12-volt accessories, such as interior lighting, climate control and the radio. The vehicle’s internal combustion engine provides power to charge the battery pack, so the vehicle doesn’t have to be plugged in to keep the battery pack maintained.
“We have several additional proprietary innovations that will make the two-mode system even more capable in high power-to-weight ratio vehicles, such as in SUVs and full-size pickups … innovations that combine our two-mode full hybrid with our extensive capability in automatic transmissions and electronic control systems,” said Stephens. “We believe it is the most efficient full hybrid design for a broad variety of vehicle configurations.”
Saturn Vue Green Line Hybrid
The Vue Green Line uses sophisticated controls and a unique electric motor/generator mated to a 2.4L VVT four-cylinder engine and 4T45-E four-speed transmission. Vue Green Line’s innovative 2.4L hybrid powertrain is rated at 170 horsepower (127 kW), a powerful increase from the 143 horsepower (106 kW) provided by the 2.2L engine in the conventional four-cylinder Vue. This maintains the vehicle’s sporty feel, with acceleration better or equal to many non-hybrid SUVs.
The Vue’s hybrid system reduces fuel consumption by:
- Shutting off the engine when the vehicle is stopped to minimize idling
- Restarting the engine promptly when the brake pedal is released
- Enabling early fuel shut-off during vehicle deceleration
- Capturing vehicle kinetic energy during deceleration (regenerative braking) to charge an advanced nickel metal hydride battery
- Performing intelligent battery charging when it is most efficient.
Additionally, the system provides additional power from the electric motor/generator during launch, when required. At wide-open throttle, such as during a passing maneuver, the system improves acceleration feel by using the motor/generator to bolster the gasoline engine to achieve maximum power.
The new hybrid system also is designed to automatically maintain full accessory functionality, including climate control, when the vehicle is stopped, so that hybrid operation is transparent to the driver and passengers. The Vue Hybrid allows an appropriate balance between fuel economy and comfort by providing a system with two driver-selected modes: ECON and HI-AC. The ECON mode favors maximizing fuel economy during idle-stop while the HI-AC mode favors maximum passenger comfort and defogging performance.
The Vue's hybrid system will cost under $1,500 (about € 1,250). The full vehicle price will start at less than $23,000 (about € 19,150). The Vue Green Line will be available in the US in the summer of 2006. It is based on the popular Vue SUV, which was restyled for 2006 with distinctive exterior appointments and a more refined interior. “The Vue Green Line is expected to be the lowest-cost hybrid-powered SUV in the market,” said Mark LaNeve, GM North America Vice President of Vehicle Sales, Service and Marketing. “Its lower price allows us to offer the fuel-saving benefits of hybrids to a wider group of customers.”
Contact:
Johan Willems
Director, Product Development
Technology Communications,
General Motors Europe
+49 6142 760243
Text and photos can be downloaded from the Internet at .