subject: Chevrolet Volt - Playground Nature Series Manufacturer - Plastic Toy Manufacturer [print this page] Classification as a "hybrid" Classification as a "hybrid"
Because the current Society of Automotive Engineers (SAE) definition of a hybrid vehicle states the vehicle shall have "two or more energy storage systems both of which must provide propulsion power, either together or independently," the company has avoided the use of the term "hybrid" when describing its Voltec designs. Instead GM describes the Volt as an electric vehicle equipped with a "range extending" gasoline powered internal combustion engine (ICE) as a genset and therefore dubbed an "Extended Range Electric Vehicle" or E-REV. However, due to the combination of an internal combustion engine and electric motors in series rather than parallel, this configuration is most commonly referred to as a plug-in series hybrid. See Hybrid vehicle drivetrain.
Design
Concept vehicle
The first Chevy Volt concept vehicle
The Volt concept vehicle has four doors with a rear liftgate, and is capable of carrying four passengers. This is a significant change in design when compared to the General Motors EV1 of the 1990s, which only seated two to reduce weight. The top speed has also been increased on the Volt, from the electronically limited 80miles per hour (130km/h) to 100miles per hour (160km/h). The battery pack size has also been reduced, from about 300 L in volume in the EV1, to just 100 L in the Volt.
GM's Vice Chairman Robert Lutz told Newsweek in 2007 that a two-seat sports car by Tesla Motors, the Roadster, and the rapid advancement of battery technology inspired him to push GM to develop the Volt.
Production model
The production design model, first revealed to the public on September 16, 2008, differs greatly in design from the original concept car. Citing necessary aerodynamic changes needed to extend the Volt's initial full-charge range, the Volt uses GM's new "Delta II" platform, shared by the planned 2010 Chevrolet Cruze and the 2011 Saab 9-3. Although GM has not publicly revealed the production model's drag coefficient, they claim it will be lower than the 0.25 drag coefficient of the Toyota Prius, which uses a Kammback body.
Electromechanical design timeline
Chevrolet Volt (concept) at the 2008 Australian International Motor Show.
GM executives report that battery technology will have a large impact in determining the success of the car.
To help spur battery research, GM selected two companies to provide advanced lithium-ion battery packs: Compact Power (CPI), which uses manganese spinel based cells made by its parent company, LG Chemical; and Continental Automotive Systems, which uses nanophosphate based cylindrical cells made by A123Systems. However, on August 9, 2007, GM established a more close-knit relationship with A123Systems so that the two companies could co-develop a Volt-specific battery cell. This cell was later unveiled at the EVS23 industry convention in Anaheim, CA. Work with CPI has continued at a rapid pace, and in late 2007 CPI delivered two fully-functional prototype battery packs to GM's testing facilities. On January 31, 2008, A123 and Continental delivered their first prototype to GM's European test facilities. GM announced on January 12, 2009 that it would use the LG Chem batteries for the production model.
GM expects ten years of life out of the batteries. As of early 2008, they had started extensive battery testing and planned to have 10-year battery results in two years. Batteries were placed in the Chevrolet Malibu for further real-world testing. In April 2008, GM Vice Chairman Bob Lutz said that the first battery test mule was now running with a lithium-ion battery pack. By that summer, GM confirmed that a non-turbocharged, 1.4 liter 4-cylinder engine would be used as the range extender, and that the intention is to build it in Flint, Michigan. In August 2008, Andrew Farah, the car's chief engineer, stated that the project remains on-track to hit the 2010 deadline saying "at this point, there nothing standing in our way of continuing to do what we said wee going to do."
In April 2009, GM allowed journalists to test the Volt powertrain in the body of Chevrolet Cruze sedans used as test mules which lacked the range-extending generator. The driving tests were conducted at GM Technical Center in Warren, Michigan. Several of the journalists noted that the Volt mule's drive in electric mode is quiet and smooth, without any of the typical noises in commercially available hybrids when accelerating or decelerating. In November 2009, a journalist described the 'feel' of driving the car as it transitioned from electric to generator mode as "the engine initial engagement is inaudible and seamless" GM plans to include in the Volt some type of noisemaker to alert blind pedestrians of the car's presence
The first integration prototype based on the final Volt design was built in June 2009, in Warren, Michigan. By October, 80 Volts had been built and tested in various conditions, and by October 2009, GM expects 80 of them to be on the road as press cars and test vehicles.
Drivetrain
Drivetrain cut-away of the Volt at the 2008 Australian International Motor Show.
Right side: the gasoline-powered engine used as generator to recharge the batteries. Left side: the electric-powered engine used for traction.
The 2007 Chevrolet Volt concept vehicle that appeared in the North American International Auto Show introduced the Voltec drive system, which is an attempt to standardize many components of possible future electrically-propelled vehicles, and to allow multiple interchangeable electricity-generating systems. The initial design as envisioned in the Volt combines an electric motor and 16kWh (58MJ) lithium-ion battery plug-in system with a small 1.0 L engine powered by gasoline linked to a 53kW (71hp) generator. The vehicle is propelled by an electric motor with a peak output of 120kW (160hp). Ordinarily, the vehicle would be charged while at home overnight. According to General Motors a full charge will take approximately eight hours from a standard North American 120 V, 15 A household outlet and less than three hours if using a standard 240 VAC outlet. Charge times will be less if the battery is not fully depleted when charging commences.
Since the electrical drivetrain is not affected by the method used to charge its batteries, several options could be available for an engine. The original prototype specifications for the Volt indicated a turbo-charged 1.0 litre 3-cylinder engine would be used. However the initial production configuration currently specified by GM indicates the use of a naturally aspirated 1.4-liter 4-cylinder gasoline engine (Opel's Family 0). The Volt will be E85 flex-fuel capable about a year after its introduction.
This drivetrain layout is considered a plug-in series hybrid design since mechanical power drives the generator, which in turn either charges the battery pack or provides power to the electric motor. While the ICE has an electrical connection with the electric motor and hence the wheels, there is no mechanical linkage to the wheels (unlike current automobile hybrid vehicles such as the Toyota Prius), allowing optimization of engine rpm for fuel consumption, efficient rate of charge, and low emissions.
GM plans to station charge the lithium-ion battery to a state-of-charge (SoC) range of approx 85%. Then once the battery depletes to a precise low set-point (
