• Jan 7th 2007 at 12:02AM
  • 22
In conjunction with the Detroit Auto Show introduction of the Chevrolet Volt concept, General Motors is also unveiling an entirely new vehicle architecture that they've dubbed "E-Flex". As the name implies E-Flex is a platform for electrically driven vehicles. The key to this platform, though, is the inherent flexibility they've designed in. During the presentation of E-Flex Beth Lowery, GM Vice-President Energy and Environment talked about the future of energy supplies. GM sees diversity as one of the keys to energy independence.

General Motors has basically bifurcated their alternative fuel vehicles into two groups, those that have wheels driven by internal combustion engines and those that don't. The first group includes the hybrids like the mild hybrids sold today in the Saturn Vue and Aura. It also includes the upcoming two-mode hybrids in the 2008 Chevy Tahoe and other vehicles. The second group comprises vehicles that have no ICE mechanically connected to the wheels. E-Flex falls into the latter category. Find out lots more about E-Flex and see more images after the jump.

(Click here to see AutoblogGreen's high-resolution image gallery of the Chevy Volt and read all about the car here.)

[Source: General Motors]
The basic framework of the E-Flex platform

The E-Flex platform was designed to be adaptable to a variety of vehicle types and sizes in a way that can be built profitably and work in a world with wide energy diversity. General Motors doesn't believe that there will be any one silver bullet to the energy problem. Instead, the future energy supply will be more regionally diversified and decentralized. Energy sources will be based on what is available locally, such as solar, wind, biomass, geothermal etc. Some future vehicles will be driven by hydrogen, some by batteries, and still others for the foreseeable future will be internal combustion. E-Flex allows GM to tailor vehicles to the energy infrastructure vehicles of a given market, such as biodiesel made from wood chips in Sweden or sugar-cane ethanol in Brazil.

The lowest common denominator of E-Flex, the framework with the electric motor in place.

The first E-flex iteration, as implemented in the Volt, is a front wheel drive vehicle with a compact AC electric motor mounted low between the front wheels. A new-generation electronics package that combines the controls, charging and inverter into a single unit mounted on the motor. There are two charging ports going out to each front fender, allowing batteries to be charged at home without an external charger. This much is common to all E-Flex variants.

The lithium ion battery is mounted in the center tunnel

The version shown in Detroit and built into the Volt has a high capacity lithium ion battery pack, mounted longitudinally in the center tunnel of the car. This configuration concentrates the mass of the battery low in the center of the car, in order optimize the vehicle dynamics. It also gives the maximum impact protection to the battery, which is important for a LiIon battery.

The generator is mounted above the motor

The current configuration also has an internal combustion engine, combined with a generator that GM calls an EV range extender. The 1.0L turbocharged three cylinder is flex-fuel capable and optimized to run at constant speed. The 53 kW engine combined with the 53 kW generator can maintain and charge the battery pack. One advantage of this is that the Volt can avoid a common EV phenomenon known as "turtling". On battery-only EVs, when the charge level gets low, the output drops and the car is unable to accelerate or even maintain speed on a grade. With the E-flex range extension, the engine automatically starts when battery charge drops to a certain level and shuts off when the battery is charged. The compact engine/generator combination sits on top of the electric motor. The 12 gallon fuel tank sits in the normal location under the rear seat. This could easily be replaced by versions that run on diesel, E100, natural gas, or hydrogen based on market requirements.

The ICE is mounted between the electric motor and firewall

E-Flex also allows for other fuel systems to be used instead of the ICE range extender/battery. If battery technology reaches an adequate level of development, a battery only plug-in variant could easily be produced.

A variant of E-Flex equipped with a next generation General Motors designed fuel cell

The biggest complaint from EV1 customers was "I was tired of planning my life around my next charge". With the range extending capability of this platform, this complaint is no longer an issue. A biodiesel variant of this application might even close in a thousand mile range on a tank of fuel.

The Chevy Volt Concept built on the E-Flex platform


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  • 22 Comments
      • 7 Months Ago
      Matt- A better engine in the Turbine family would be the StarRotor continuous-cycle engine http://peswiki.com/index.php/Directory:StarRotor_Corporation The StarRotor is said to be 3-4 times more efficient than the best IC engines. It’s hard to change the status quo. You know, fear, turf, money, power that kind of thing. Personally, I kind of like the MYT engine concept, but any rotary type design makes more sense than rapidly accelerating, decelerating and ultimately reversing the direction of mass. What a terrible waste of stored inertial energy.

      There are new technologies under review. Take a look here for some very interesting reading. http://www.peswiki.com/index.php/Congress:Top_100_Technologies_--_RD
      • 7 Months Ago
      Hey guys, I entered this blog a little late. I am just tinkering on a conventional small 4 seater car with an electronic ignition 47 bHP IC spark ignition gasoline engine. After flexing it to ethanol with a retrofit kit, I will try to adapt an LPG converter too. All is front wheel drive.

      Then aim to add twin 10 HP electric motors, one on each rear wheel, with belt drives (act as overdrive clutches too).

      Elec motors coupled to a sensor on the steering column, to provide just enough velocity difference, so as to act as differential on curves. No losses on a gearbox for the electric motors.

      Cyclic deep discharge batteries to feed the elec motors will be charged by plug in the wall system, or a thin plate technology solar panel on the roof and bonnet, or a micro wind generator (of minor effect on overall charge, main aim of eolic will be just to include this source too). Finally a motion charger as the dynamo on your average bicycle.

      Will have to get rid of the back seat for all this of course.

      Main aim is not to produce an experimental highly inneficient in any one single fuel source home made car, but to eventually act as a prototype for a future "your 1st brand new car" concept for a young environmentally conscious just married couple, at an attractive price.

      Anybody know of successful multi cylinder Stirlings aboard cars? Running on external combustion produced by pruned wood chips, etc.? Cheers,
      • 7 Months Ago
      "The biggest complaint from EV1 customers was "I was tired of planning my life around my next charge"."

      things that make you go hmm...

      I always thought they were pissed about GM crushing them...

      Must've been a quote from before GM crushed the EV1s... But imagine the technology if they would have kept pushing... they wouldn't be complaining about lack of battery technology on this car.
      • 7 Months Ago
      FWD arrangement was likely chosen for winter driving in northern climates. As this will be an economy car, it's unlikely to have traction control and stability control that make the newer rwd cars work for the average untrained driver.
      • 7 Months Ago
      It's great to see a major automaker finally moving forward on what small companies have been proving possible for several years (see Energy CS, CalCars and HyMotion). But while the announcement is exciting, GM still isn't giving any solid timeline on WHEN we can see these cars on the road or HOW MANY cars are actually going to be produced - at best they say 3-4 years if the battery technology is available. There is a demand for plug-in hybrids NOW - there are hundreds of cities, counties, utility districts and fleets already placing "soft orders" for such vehicles. Such early-adopters of these vehicles would provide test markets for GM to refine the technology and build public confidence and interest in these cars.

      I have to admit I'm a little concerned that they will use the announcement of these concept cars more to clean up their image than clean up their product line. There is a lot GM can do between now and when we may see these concept vehicles actually on the road.

      We all know increasing fuel efficiency is the direction automakers need to head – so let’s get past the hype of a handful of concept vehicles and look at what they are doing with the rest of their fleet. Overall average fuel economy from the Big 6 is worse today that it was 10 years ago and GM is still heavily dependent on its gas guzzling truck lines. In addition to that they are still fighting tooth-and-nail against increasing fuel economy regulations, suing states that try to limit greenhouse gas emissions, and in December argued before the Supreme Court that carbon from tailpipe emissions was not even a pollutant. GM is still planning to expand their Hummer line to become 25% of their overall sales. Consumers still have limited options to find fuel-efficient cars that are affordable, well-built, and fun to drive. There are plenty of things automakers can do today to increase fuel economy – and I'm tired of being shown distracting concept cars that we won't see for 3-4 years if ever.

      I've been working with the Freedom From Oil Campaign to make automakers honestly prioritize fuel economy and move beyond oil – check out what we do at http://www.FreedomFromOil.org
      • 7 Months Ago
      The electric gas hybrid has been arround for quit a few years. Mother Earth News showed an Opal G T in the early 70's. with simple plans that a home tinkerer could build. In the 90's they started the solar electric 250 in pheonix Az. my thought is to re-invent nascar on an electric drive car basis, weather it be gas, diesel or hydrogen powered generator drive systems. Lets expand this thought to quarter mile drags , as we seen in the 60's. times were good the economy was great and life was good. we need change and we need it now. it would surely be good for the economy,new jobs and all. Please let the little class people have a chance, and the giant oil mogalals not so greedy and give our earth a chance to heal.
      • 7 Months Ago
      Historically, it has been the case that the fundamental "problem" with petroleum fueled vehicles is that once the petroleum product is expended (gasoline, diesel fuel, etc.) the vehicle will not continue to function. Similarly, with battery powered vehicles, the fundamental issue is that when the battery runs out of charge, the electric vehicle can no longer function.

      It seems obvious to most people that it is practical to add more liquid fuel to a petroleum powered vehicle, but it surprises me that little suggestion is mad of an obvious paradigm shift in how electrical vehicles are considered: why is it not considered within the realm of possibilities to simply swap out the battery of an electrically powered vehicle every 250 or so miles or so in exchange for a fully charged one (that technique seems to have worked pretty well for most of the flashlights I have ever owned)? OK, maybe with lead/acid technology such a scenario might be practical, but I wonder if any consideration been given by the 'Big Three' of establishing lithium ion battery replacement/recharge stations to service commuter vehicles of the (hopefully near) future? Certainly near term robot/battery technology should be close to the point that such a scenario would be at least conceivable. I suppose arguments against investing in a new industry of that sort might be storage infrastructure (although I suspect the volume of an underground gasoline tank vs. a bank of charging batteries would come close to balancing) or transportation infrastructure (so maybe they would need to add a few new substations to the elex grid), but these arguments don't really seem to be show stoppers at least for nascent technology/industry consideration...
      • 7 Months Ago
      #8. The Turbine powered Car was powered by a "comprex" I think with mercedes. And even Mazda I thought did some work with turbine engines recently. Biggest issue is the spool up, but noise is a large issue.

      #12. Still what about a turbo compund deisel engine? Or are the biggest drawbacks of hydraulic transmissions the weight, leakage and safety?
      • 7 Months Ago
      Other than the realities of battery technology, I have another concern. I live in Minnesota. It tends to get cold in the winter and hot in the summer.

      Traditionally, heating a car's passenger space is done with waste heat generated by the ICE. In the summer, air conditioning also consumes energy.

      How does heating the passanger space in the winter and cooling it in the summer affect the milage expectations of the this or similar concepts?

      • 7 Months Ago
      I'm pretty sure this is exclusively GM technology. The Lithium-Ion batteries will have to be sourced from someone like Sanyo.
      Chris Barron
      • 7 Months Ago
      They can't outsource battery developement, because on the whole it belongs to Chevron.

      Watch out for a company called cobasys. They bought NiMH battery patents to stop Toyota making any more RAV4 electrics, they have also just bought A123 who make some of the best Lithium ion batteries.

      Cobasys are majority owned by Chevron......hhhmmmmm, anyone for a game of Monopoly ?
      • 7 Months Ago
      The requirement that battery technology has to improve is stupid. It has been stalling electric cars for over 100 years. Any battery powered will have a limited range. The limit could be 20 miles or 200 miles but it is there. When the battery range is exceeded the "range extender" kicks in. This car could be built with the current crop of sealed lead acid batteries and be effective. If the battery range is only 20 miles, so be it. Truth is that 20 miles would be enough that many drivers would never have to start the engine. The "waiting for better batteries" line makes this appear like more GM stonewalling while appearing to be doing something. If they were serious they would be taking down payments for cars to be delivered in 2009. I'd buy one.
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