JMU AFV Lab Blog

These two items from gizmag and AutoblogGreen came to my attention recently.

The first, immediately below, from gizmag, introduces a novel system for an electric bicycle that uses both a hub mounted motor and a separate hub mounted battery on the other wheel.  This struck me as quite an interesting idea.  Having never ridden an electric bicycle of any kind, I can only speak from what I suppose to be the case.  With that caveat, I have always thought that the battery pack on any electric bicycle I have seen heretofore was mounted much too high for stability.  It seemed to me they were all mounted up on the top frame tube or on the down tube coming down from the fork bearing tube.  Of necessity, they had to be high so not to interfere with the riders legs when pedaling.  Having the battery mounted in the hub would seem to me to make for a lower center of gravity and, thus, a more stable bike.  Having the probable weight distribution close to 50/50 would have to make for a better handling bike, too.

Even though it’s dated earlier, the second item, from AutoblogGreen, initially fascinated me, as it combines motor, battery, control system, and charger in one hub.  It also adds a Bluetooth wireless throttle control, too.  Talk about state of the art, this concept has all the bells and whistles.  Then I started really analyzing it and I kind of lost my initial enthusiasm.  I can’t help but think that all that weight biased to one end or the other would negatively affect handling.  I also can’t see how they are going to get a big enough battery in that hub to deliver the performance they claim.  I suppose the bluetooth solves the problem of wiring a control on the handlebar to the wheel, but I can’t help but think it’s overkill.  It appears to me to be a solution in search of a problem.

Sources:  http://www.gizmag.com/e-electric-bicycle-electric-motion/11059/ and http://www.autobloggreen.com/2009/02/19/mit-greenwheel-simply-an-electric-bicycle-revolution/

February 23, 2009 With the increasing popularity of the electrically assisted pushbike we are starting to see some innovative designs hit the market. While hub motors are the number one solution for mounting the electric motor within a bike frame, either in the front or rear wheel, mounting the battery pack and motor drive electronics has remained a challenge when taking into consideration practically and aesthetics. The folks at Electric Motion Systems think they have the answer with a combination of a 750 watt rear wheel mounted hub motor with built-in motor drive electronics paired with a battery pack mounted in the front wheel hub.

e-electric bicycle

The E+ Electric Bike is available in six styles of bike that are all a variation on a hard-tail mountain bike. The E+ comes standard with a 750 watt BLDC rear hub motor but there is a high torque 85 Nm 1kw hub motor as an upgrade option. Both hub motors have built in inverters so there’s one less box to find mounting space on the bike frame for. The front hub mounted battery pack is something we’ve never seen before on an e-bike. The internal layout is very similar to a hub motor with the stationary inner structure (called the stator) attached to the axle while the outer housing is attached to the rim via spokes and rotates as part of the wheel. Thirty NiMH battery cells are arranged in six groups of five cells arranged in a polygon layout parallel to the axle and mounted on the stator. The battery pack puts out 36 volts at 9 amp hour giving a battery capacity of 324 watt hour. (0.324kw/hr). No electric only range is quoted as this is very dependent on terrain, how much you pedal and the amount of regeneration possible but each battery charge should give between 20 and 40 miles (32 – 64 km). A full charge from a 110v wall socket will take four to six hours and cost about $0.03.

The E+ has a handlbar mounted LCD display where the rider can select 19 different cycling modes that range from full electric to pedal only modes. One of the E+ modes offers to let you set the cycling mode for increased resistance to give you a greater workout even if there are no hills in sight. While this could well be a useful feature, it also highlights one of the side effects of BLDC hub motors - they do not freewheel. Because a BLDC hub motor contains permanent magnets even when no power is applied there is still magnetic attraction between the magnets and the poles on the stator meaning there is always cogging resistance. The company says this should only be a problem with a flat battery on extended flat surface riding, as with any kind of undulation the motor will regenerate on the down hills just enough to provide power assistance up the next hill.

The LCD-display also shows speed, distance traveled, battery capacity, cruise control option, and 19 cycling modes. It also displays trip-specific data such as distance of trip, duration, and average speeds. Pocket-sized and removable for safe and easy storage, when the display is removed, the battery is disabled and the motor is put into full resistance mode, making pedaling virtually impossible. This unit has backlighting (0-100%) and automatically adjusts the contrast of display depending on outdoor conditions.

The Electric Motion Systems E+ Cruiser and E+ Mountain Bike cost USD$3,495.

One definition of the word elegant is “to be gracefully concise and simple.” In the future, the dictionary just might include the GreenWheel as a product that illustrates this principle perfectly. From the MIT Smartcities team that gave us the stackable cars concept and the RoboScooter (still a go), comes a wheel that can turn an ordinary bicycle into a very desirable electric one in an easy, cost effective manner. Enclosing a motor, A123 Systems batteries and a generator into a small aluminum pancake hub, the GreenWheel can give you up to 25 miles of propulsion, or much more if you don’t mind pedaling. Unlike conversions kits from the past, it forgoes running wires the length of your bike by incorporating the magic of bluetooth to control the twist-throttle.

Over a dozen different configurations of the GreenWheel are scheduled to be tried and tested by a variety of cyclists this spring. Once the the team analyzes their feedback, an ultimate configuration of power, speed and cost will be settled on and mass production will get under way. With an estimated cost of “several hundred dollars,” they better plan on making a lot of them since not only are they a wonderful “solution” for several cities and ridesharing programs already showing interest, but in a world-economy that can’t afford to buy cars the way they used to, the GreenWheel should have a bright future.

[Source: MSNBC]

Came across this item in the Science Daily newsletter I get. At first glance, it would seem to be a simple solution to the problem of efficient vehicle propulsion. The concept is to use compressed air to store energy instead of a battery as in a conventional hybrid vehicle. The curious twist here is using the compressed air to assist the conventional internal combustion engine by either direct pressure on the pistons or as a turbocharger. The theory seems to have merit; compressed air is as viable a means of storing energy as a battery and turbocharging can drastically improve the efficiency of an ICE. However, my personal experience with compressed air as a means of energy storage and transfer is that it is highly inefficient. There is quite a bit of heat generated when air is compressed. After all, a diesel engine depends upon the same heat of compression to ignite its fuel. Shop air compressors require substantial cooling fins on both compressor heads and on connecting piping and large fans to keep compressors from self destructing. And shop air is usually only about 120 psi or so. All this heat that must be expelled is lost energy. As a practical matter, I am skeptical of being able to design a compressor and pressure storage tank with enough capacity to overcome this heat loss and be practical and still be lighter than the electric motor, generator, and battery of a hybrid like the Prius or Escape.

Source: http://www.sciencedaily.com/releases/2009/01/090131113216.htm

Saving Gas: Pneumatic Hybrid Engine Is Much Cheaper Than Electric Hybrids And Almost As Economical

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Physics laboratory technician Till Coester works on the new hybrid engine being checked thoroughly on the test stand. (Credit: Photo: P. Rüegg / ETH Zurich)

ScienceDaily (Feb. 4, 2009) — A pneumatic hybrid engine could be used to power vehicles in the future. The benefit of this technology: it is much cheaper than today’s electric hybrids and almost just as economical.

The Japanese automobile manufacturer Toyota has built a car, the “Prius”, which is seen as a concept for the future. It uses an electric hybrid engine to save fuel while still offering the usual drivability standards. However, this vehicle has a serious disadvantage. It is expensive and is unaffordable especially for consumers in up-and-coming countries such as China and India that are increasing rapidly their mobility demands. In addition, the battery needed by the electric hybrid as an energy storage device is heavy and expensive. Last but not least, the technology in the coupling between the gasoline engine and the electric drive is very complicated.

Simpler and cheaper

This is why Lino Guzzella, Professor of Thermotronics, does not think the electric hybrid is the only solution. As an experienced engineer, he therefore looked for an approach that was simpler than an electric hybrid but remained affordable even for people with less purchasing power. Guzzella explains that “The apple must be ripe but still hang just low enough to stay within reach.” The ‘fruit’ ripening in his group is the pneumatic hybrid drive. The concept is simpler than that of an electric hybrid: the new hybrid engine has a compressed air tank connected to the engine instead of a battery unit. When required, e.g. when starting from rest or after changing gear, compressed air flows into the engine through an electronically controlled valve. If fuel is also injected, the engine responds quickly. Although the system used to control the valve is also technologically complex, this challenge can be mastered nowadays thanks to powerful algorithms and computer systems.

The compressed air supply also allows the engine constructors led by Lino Guzzella to achieve extreme downsizing. Conventional car engines can have peak powers of 150 hp or more, but usually need no more than 30 hp for everyday driving. Downsizing the engine halves the number of cylinders from four to two. This also halves frictional losses and increases the engine’s average efficiency. To keep the maximum power and thus satisfy the consumer’s drivability demands, the engine is highly supercharged by a turbocharger – which exploits the exhaust gas enthalpy as an energy source, and which boosts the to the desired levels..

Efficiency up by a third

Initial tests on the test stand in the ETH Zurich Machinery Laboratory show that Guzzella and his group are on the right track. They were able to increase the engine’s average efficiency in the European Test Cycle from 18 to 24 percent. This corresponds to a fuel saving of one third. Energy savings of up to 50 percent are achievable in purely urban traffic, because the engine can pump air into the compressed air tank during braking, thus recovering the kinetic energy.

Although the fuel saving achieved by the pneumatic hybrid is not as large as that of an electric hybrid, it still amounts to 80 percent of the latter. In return, the price-performance ratio is distinctly better. So good, in fact, that Guzzella can imagine the pneumatic hybrid also being suitable for use in poorer countries. He estimates the additional costs compared to a conventional gasoline engine to be approximately 20 percent. On the other hand, the additional costs for an electric hybrid are calculated to be at least 200 percent.

Motor manufacturers interested

The new engine concept has aroused the interest of several major motor companies and automitive suppliers, who have obtained information on-site. Some of the ideas of the new concept have already been patented. Only the financial crisis and the global recession worry Guzzella slightly. He says that these are difficult times in which to launch a new drive concept. Nevertheless, he is convinced that he will find people interested in adopting this system, since no other technology is on the horizon that could replace the internal combustion engine, even in the next two decades. This is why the way leads via hybrid concepts, which remain affordable while retaining the advantages of a gasoline or diesel engine.

Source:  http://www.sciencedaily.com/releases/2009/01/090131113216.htm

I ran across this item on the Autobloggreen.com website today. The picture doesn’t really correspond to the title’s promise, as the four seat, wheelchair accessible version would be the one most likely to use Handicapped Parking. However, it uses diesel power in a Plug In Hybrid Electric Vehicle. Diesel makes more sense in a PHEV, to my way of thinking. When you consider all the single speed stationary pumps and generators out there that are diesel powered and have already proven their efficiency and durability, it is evident that diesel would be a logical choice for recharging batteries in a PHEV. After all, there are thousands of diesel powered semitrailer refrigeration units like ThermoKing or TransiCold out there plugging merrily along for years in applications and environments that make a PHEV look like a garden party. And all of the modern diesel emissions controls like regenerative particulate filters and high pressure common rail fuel injection systems make the “stinking, smoking old diesel” a thing of the past. Diesel seems like the ideal ICE solution for a PHEV. Go to http://www.autobloggreen.com/2009/02/01/whats-green-three-wheeled-and-can-park-by-the-blue-signs/ to see the original post and comments. Also, go to http://www.biotrike.com/ for the home page of the Bio-Trike.

What’s green, three-wheeled and can park by the blue signs?

by Sebastian Blanco on Feb 1st 2009 at 9:24AM

Using fewer resources to get around isn’t limited to any particular group of people. Heck, there are more 43 percent electric wheelchairs in the U.S. than electric vehicles (this statistic brought to you by the Department of Made Up statistics, but I hope my point is clear). If you often travel in a wheelchair but like the idea of an aerodynamic, biofuelled ride for your longer trips, check out the BioTrike-B3XH. Sure, all of the standard add-on equipment that helps the differently-abled (is that the right term these days?) drive an SUV would work just as well on the Volt or the Focus EV, but the BioTrike (the four-seat version, anyway) has been designed from the ground up to be accessible to people who use a wheelchair or are in other ways physically handicapped.

The BioTrike is a tadpole-style three-wheeled plug-in hybrid vehicle that burns diesel (or biodiesel, natch) in a Caterpillar-sourced engine. The builders claim that the range with a full tank and a full charge is somewhere between 700 and 900 miles. They don’t give a lot of details on the powertrain, but do say that the BioTrike has a 50-mile electric-only range. Prices start at $23,999 for the two-seat version and rise to $35,999 for the four-seat, wheelchair-ready version. Options extra.

Source:  http://www.autobloggreen.com/2009/02/01/whats-green-three-wheeled-and-can-park-by-the-blue-signs/