GM E-Flex platform

Infobox Automobile platform
name = GM E-Flex platform


aka =
manufacturer = General Motors
predecessor =
successor =
production = 2010–present
class = Extended-range EV
similar =
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transmission =
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E-Flex is a future General Motors' automobile platform slated to be released in late 2010. E-Flex initially uses a plug-in capable, battery-dominant series hybrid architecture. The E-Flex vehicles are all electrically-driven, feature common drivetrain components, and will be able to create electricity on board (either through a genset or a fuel cell). Regenerative braking will also contribute to the on-board electricity generation. (“E” stands for electric drive and “Flex” for the different sources of electricity.)cite web
last =
first =
title = GM Introduces E-Flex Electric Vehicle System; Chevrolet Volt the First Application
publisher = Green Car Congress
date = 2007-01-06
url = http://www.greencarcongress.com/2007/01/gm_introduces_e.html
accessdate = 2008-08-09 ]

Drivetrain

The E-Flex drivetrain was initially demonstrated in the 2007 Chevrolet Volt concept vehicle that appeared in the North American International Auto Show cite web|url=http://www.thecarconnection.com/Auto_News/Green_Car_News/GM_Plugs_Fuel_Cells_into_Volt.S196.A12244.html|title=GM Plugs Fuel Cells into Volt|first=Paul A.|last=Eisenstein|date=2007-04-19|publisher=The Car Connection] which introduced the E-Flex drive system as an attempt to standardize many components of possible future electrically-propelled vehicles, and to allow multiple interchangeable electricity-generating systems. [cite web|url=http://www.autobloggreen.com/2007/01/07/detroit-auto-show-general-motors-e-flex-platform/ |title=A look at the GM E-Flex platform |first=Sam |last=Abuelsamid |work=AutoBlogGreen.com |date=2007-01-07 |accessdate=2007-01-13] The initial design as envisioned in the Volt combines an electric motor and convert|16|kWh|MJ|abbr=on|lk=on lithium-ion battery plug-in system [cite web|url=http://www.chevrolet.com/pop/electriccar/2007/process_en.jsp | title=E-Flex drive system | accessdate=2007-10-01] with a small engine (1 liter) powered by gasoline linked to a convert|53|kW|hp|abbr=on|lk=on generator. The intitial production Volt will be propelled by an electric motor with a peak output of convert|120|kW|hp|abbr=on. Ordinarily, the Volt would be charged while at home overnight (plug-in hybrid-mode) through one of its two charging ports for convenience, one on each side of the vehicle. [cite web|url=http://www.cnn.com/2007/AUTOS/01/07/detroit_chevrolet_volt_concept/index.html |title=GM shows Chevy plug-in concept |publisher=CNNMoney.com |date=2007-01-08 |accessdate=2007-01-12] A full charge reportedly takes 10 hours from a standard North American 120 V, 15 A household outlet.

Since the electrical drivetrain is not affected by the method used to charge the batteries, several options could be available for acting as an electrical power source. The primary configuration specified in the Volt promotional literature uses a turbocharged 1.0-liter engine with three cylinders, a flex-fuel engine capable of running gasoline or E85 (85% ethanol, 15% gasoline).

Another engine-driven power option would be a pure ethanol (E100) engine, a diesel engine capable of running biodiesel fuel, or even a hydrogen fuel cell, once that technology becomes practical. (The Ford Airstream concept, which debuted at the same show, uses a fuel cell plug-in hybrid design.)

A second power-source option, one that does not rely on an internal-combustion engine at all, was demonstrated in the Volt fuel cell concept vehicle, which appeared in the 2007 Shanghai Auto Show. Due to the high cost of fuel cells compared to newer lower cost lithium batteries, General Motors has publicly suggested that the Volt will not be using fuel cells in any near term production vehicles. [cite web|url=http://online.wsj.com/article/SB120468405514712501.html |first=Edward |last=Taylor |title=GM, Toyota Doubtful on Fuel Cells' Mass Use |date=2008-03-05 |accessdate=2008-04-08 |publisher=Wall Street Journal]

The general layout of the initial production platform is considered a plug-in series hybrid design since mechanical power initially drives the generator, which in turn charges the battery pack. Power is then drained from the batteries to run the electrical motors which move the vehicle. The internal combustion engine does not have any mechanical linkage to the wheels (unlike current vehicles such as the Toyota Prius), and can run at a constant speed for both optimal efficiency and mechanical simplicity (i.e., there is no need for a multi-valve, multi- or variable-cam design). The Volt is expected to get convert|50|mpgUS|L/100 km|abbr=on if the battery is discharged, or convert|150|mpgUS|L/100 km|abbr=on if fully charged every convert|60|mi|km|abbr=on. [cite web|url=http://www.usatoday.com/money/autos/2007-01-07-volt_x.htm|title=Chevy Volt concept offers 150 mpg, but the plug-in hybrid needs a new technology|first=Chris|last=Woodyard|accessdate=2008-07-04|date=2007-01-07|publisher=USA Today]

GM plans to keep the lithium-ion battery in the initial E-Flex production vehicle in a state-of-charge (SOC) range of between 30% and 80%, with the on-board generator starting to recharge the battery at the 30% level. [cite web|url=http://www.gm-volt.com/2007/08/29/latest-chevy-volt-battery-pack-and-generator-details-and-clarifications/ |title=Latest Chevy Volt Battery Pack and Generator Details and Clarifications |first=Lyle J. |last=Dennis, M.D. |work=GM-Volt.com | accessdate=2007-08-29]

GM has decided on a new descriptive terminology distinct from calling it a hybrid. They are calling the Volt an E-REV, for "extended-range electric vehicle". [cite web|url=http://www.gm-volt.com/2007/11/23/gm-calls-the-volt-an-e-rev/ |title=GM Calls the Volt an E-REV |first=Lyle J. |last=Dennis, M.D. |work=GM-Volt.com | accessdate=2007-11-23] This is in part justified since there is no mechanical linkage between the petrol engine and the wheels. The design is conceptually similar to a modern electromotive locomotive, with a generator, an electric motor, regenerative braking, with the addition of a storage battery.

Concept Vehicles

* Chevrolet Volt
* Cadillac Provoq
* Opel Flextreme

Vehicles slated for Production

* Chevrolet VoltGM chose its Global Compact vehicle architecture (Cobalt-sized) for its first E-Flex application, the Chevrolet Volt. GM has announced that the car is on track for a 2010 launch.

References