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Mavizen TTX02

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Comoto

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KTM Freeride

 

 

 

 

 

 

 

 

 

 

 

 

 

Green Sun Electric Vehicles

Design Philosophy          Projects               Vaporware

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 Design Philosophy  - Lightweight & Fun

 

This area of vehicle design is intriguing, has so much potential and is ripe for exploration. Our design philosophy is not to replicate a typical IC passenger vehicle in electric. There are innumerable entities trying to do just that and fighting design constraints all the way. The current reality is that unless you can spring for a very advanced, and therefore very expensive lithium ion or nickel metal hydride battery packs and their respective controller configurations, you are not going to achieve very good performance in an all electric full size passenger vehicle.

The key to getting reasonable performance with a lower spec, relatively inexpensive battery pack is to maximize the percentage of total vehicle weight allotted to the battery pack. This is exceedingly difficult to do using a conventional automobile platform as a chassis to carry the electric drive system. I think the fundamental mistake is trying to replicate the standard IC vehicle in an electric drive form. They are not remotely comparable in price/performance. Not in price for the advanced battery/drive systems and not in performance for the low tech battery/drive systems. 

Our solution is not to fight this reality but to explore a niche that we believe presents the possibility of an acceptable price performance ratio, lots of fun, takes real advantage of the electric drives desirable characteristics and minimizes some of the drawbacks that they truly do have. We believe the best path is to concentrate on boosting the battery packs contribution as percentage of total vehicle weight. We have no intention of replacing your daily vehicle, although for some adventurous and hardy souls this is entirely feasible. Essentially, you just give up the idea of a weather tight climate controlled box in which to sit while you drive. Motorcycle riders may be particularly comfortable with this concept as they are very familiar with dressing to deal with the weather as it is. We are proposing designs that dispense with the weight and complexity of exterior and interior sheetmetal body work, double wall doors full of lock and window mechanisms, glassed in interior boxes with upholstered interiors, HVAC systems, etc. We are proposing essentially an open air tube framed vehicle. Frame, wheels, brakes controls and electric driveline, only the essentials necessary to propel and control the vehicle. The driver dresses with full exposure to the weather in mind. The goal is to end up with 30 – 50% or more of total vehicle weight devoted to the battery pack. Reasonable, perhaps even spirited, performance with lead acid chemistry, the least expensive and most widely available battery packs, may be achievable. When the time arrives that you can plug in a reasonably priced advanced battery pack and controller, you may end up with quite the hot rod. 

Think of motorcycles, sidecars and desert racing buggys as the vehicle platforms and you get an idea of a what tube framed designs would look like.

 From a practical standpoint, the reality is that inexpensive EV's are short range vehicles under the best of circumstances. Mixing in extreme changes in terrain ( read uphills ) can seriously compromise that limited range if the vehicle is not designed correctly to accommodate them. As excited as we are about EV's and their potential, the current price of the ones with advanced battery/controller packages makes us cringe a wee bit. Considering that the vast majority of most people's trips are short hop interurban journeys, range limitations aren't necessarily a serious problem. But of course we want it all and within a reasonable budget. We believe there is a way to use a relatively inexpensive EV as in around town ride but also allow the capability of longer journeys as well. We would accomplish this with an addition called a range extender. This is typically an internal combustion engine ( ICE ) that runs a generator for recharging the vehicle’s onboard battery pack. We have full faith that eventually the price performance of battery powered EV's will surpass that of ICE vehicles. Until then, as much as we would like to steer clear of ICEVs ( kind of feels like mixing oil and water, or perhaps oil and electricity ), we think this is an effective solution for achieving range in your EV.  In our preferred design, the ICE/generator package is self-contained and quick detach so it can be installed and removed quickly. Therefore, you aren't dragging it around town when it's not needed.

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Green Sun Electric Vehicles – Projects  

For now all of our electric vehicles are still in the conceptual stages so no metal has been bent yet, but here are the basic platforms we have in mind. Since our design philosophy expresses very strong feelings about the difficulty in achieving an acceptable balance of price and performance when trying to duplicate all of the attributes of a conventional passenger vehicle, all of the projects we propose are centered on the concept of vehicles in which the battery pack is a high percentage of total vehicle weight. Consequently, for most of the projects we are pursuing, either vaporware or in the flesh, our primary design focus is to reduce the list of components to the essentials necessary for a rolling chassis. One useful distinction we use in designing vehicles is to think of them in terms of the number of wheels they have, or don't have, such as watercraft or flying things. So, here are our general ideas about wheeled EVs designed as lightweights from the start. Whether scratch built or converted from an existing vehicle, this will be the central guideline we follow. 

Two wheeled or monotrack platforms. Much as we salivate at the idea of an electric motorcycle, the reality of a lead acid powered two wheeler of even moderate range at highway speed is still a very heavy, ungainly hunk of iron. The starkly inferior performance in range and handling of a bike rebuilt with electric compared to its IC powered version is so because the non powerplant weight of the bike is already near as low as possible. Substitution of batteries as fuel supply significantly raises the weight of the vehicle and severely alters the weight balance. Advanced battery packs and drive systems put a very usable, albeit very expensive electric motorcycle on the near horizon. For now, a relatively low speed electric bicycle is the only well balanced monotrack platform. Lots of possibilities here. The moderate  speeds and short distances of in town use make it fairly simple to find an acceptable compromise of weight, handling and performance. The exceptionally low weight of a typical bicycle chassis is extremely advantageous as a core for an EV project. 

Three wheeled platforms. Three wheeled vehicles come in two fundamentally different formats, fixed wheel and leaners. Within each format there are a number of variations. In a fixed wheel format all of the wheels remain perpendicular to the ground under normal circumstances. In a leaner format, they do not. Some leaner designs are very intriguing but there is a level of complexity there that we have never seriously investigated. There are essentially three formats for the three wheel fixed platforms; tricycle, tadpole and sidecar. Tricycle configuration has one wheel in front and two in back on a common axle. The tadpole configuration has one drive wheel centered in back and two steering in front on a common axle centerline. Sidecar configuration locates the front steering wheel and rear drive wheel on a common plane and the third wheel in its own space of to the side of and forward of the drive wheel. In our opinion the handling dynamics of tricycle design are unsuitable for high speed road work so we will disregard that option here.

The tadpole could work very well as a pavement ride but the only existing tadpole chassis are bicycle grade components, there are few if any readily available chassis for a project core, so custom built would be the only practical option. Another strike is the typically low rider position with the tadpole configuration makes it very difficult to see and be seen in congested urban traffic. The third strike is the center rear wheel position makes the vehicle a three track configuration, which can be exceedingly difficult to use on an unpaved surface with typical two track wheel tracks worn in.

The sidecar is the least complex example of a tube framed vehicle that is eminently suitable for electric drive in a high speed chassis. Precisely speaking the sidecar is, in fact, just the framework, passenger compartment and third wheel, which is then attached to a motorcycle chassis. This combination, although frequently referred to as a sidecar as well, should really have a name that differentiates it from the sidecar itself. The terms outfit and hack are commonly used but I don't care for either so I guess I'll just continue using sidecar to refer to both the car itself and the whole rig. Hopefully the context will make it clear which I'm referring to. Sidecar handling dynamics are well documented and suitable chassis are commonly available. In fact, it is a relatively simple matter to add a sidecar to most any motorcycle chassis. As with the motorcycle, the basic chassis is already close to optimal in terms of powerplant/fuel to chassis weight so there is not much excess componentry you can remove when you replace the IC engine with an electric drive system. However, you can add significant additional weight via the batteries without severely compromising the sidecars handling. The key here is in paying close attention to weight distribution. One compromise you must consider is that you may have to give up the sidecar’s utility for carrying a passenger, rendering it a solo machine. The reality of this may depend on the variety of battery layouts deemed possible for optional designs. A peculiarity of sidecar handling dynamics is that they need ballast in the sidecar to stabilize the handling. This ballast often takes the form of a passenger or cargo. Without ballast the driver of the rig must exercise a great deal of caution depending on the nature of the road. With the ballast provided by a battery pack, the sidecar could be tuned to be stabile with spirited solo riding. By the way, sidecars are a real hoot in the snow. It may be possible to configure the battery pack in away that accommodates a passenger while maintaining both acceptable solo and passengered handling characteristics. ( see the discussion regarding range extenders in the four wheeled platform section, it should generally apply to sidecars as well ) 

Four wheeled platforms. This is the platform where tube frame really promises significant advantages. A conventional vehicle is encumbered with much superfluous material. The possibility for significant weight reduction, or perhaps better thought of as a trade for battery weight is compelling. Although there are a variety of design possibilities, the configuration that appeals to us most is a two seat tandem arrangement, driver forward passenger aft, with seats positioned along the spine of the chassis. This narrow passenger compartment permits outboard pods to contain the battery packs, one on either side of the passenger compartment, which keeps total weight as close to the centerline as possible. The stripper version would entail neither glass, body panels, nor interior -- other than the seats, necessary controls and instrumentation. The next step up in complexity might include a windshield and a body panel for the nose area to improve aerodynamics. Both driver and passenger would wear helmet and clothing suitable for the ambient weather conditions, Electrically heated suits, gloves, etc. would be an option, significantly extending the tolerable range of weather conditions. Electrically heated 12V clothing is relatively low draw power and should not significantly affect the reserves available for operating the vehicle. 

The ideal platform would include four-wheel-drive, a low range transfer case and selectable lockers in both axles. However, All of these components add weight to the system and may not be essential depending on the power and traction characteristics of the electric motor and drive train. Although a custom tube type chassis gives the freedom to accommodate a variety of drive line layouts, it would be the most design and money intensive choice. The simplest, least expensive layout would probably use a air cooled Volkswagen type I components as a foundation. For the first project it may be expedient to start with a early Beetle pan, complete with front suspension, rear suspension and transaxle. We would fabricate an upper structure of tubing, then locate the seats and a complete steering mechanism on the centerline over the tunnel. Additional changes would concern modifying the remaining pan into a battery pack support or perhaps replacing the sheet metal entirely with battery pack cages fabricated from tubing. Conversion kits to lash electric motors to Type 1 transaxles are commonly available. If the VW transaxle is deemed an essential starting point, the only clean route to achieving four-wheel-drive is probably to acquire the transaxle, front drive line, and front differential from a VW Synchro Vanagon. I believe the single transaxle is also equipped with a granny first gear, a very useful feature. However, the Synchro driveline is likely to be an expensive proposition.

A potentially interesting alternative for a four-wheel-drive EV would incorporate the transmission/transaxle from a Honda or VW front wheel drive, but turned 90° from its OEM orientation so that the axle outputs go front and back, lashing up to differentials in a conventional location, yielding a four-wheel-drive line. The transaxle from a Civic 4WD wagon of the mid-80s is also blessed with a granny first gear. Conversion kits that make electric motors to Honda or VW front wheel drive transaxles are also fairly common. However, a design incorporating either transaxle would demand a completely custom tube chassis.

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The  Range Extender

The VW based platform, in particular, does open up another, very interesting possibility. The combination of electric motor and VW transaxle sets very low in the chassis. The open space above may present an excellent opportunity to install a self-contained range extender package. The package would be IC-based, ( fuel type to be determined ), powerplant/generator combo, fuel container, exhaust, and electrical system interface -- all be mounted on a base plate. The entire assembly is, in turn, is mounted, via quick detach, to brackets on the frame tubes. With all connections to the chassis Q.D., the complete extender package could be lifted in and out of the chassis. With the range extender package designed thusly, the vehicle could be used as an urban runabout in electric only mode and as cross country cruiser with the range extender package in place. Calculations regarding the watts hours required to maintain a constant cruising speed are well documented, primarily based on vehicle weight. I am sure that knowing the coefficient of drag would permit calculating those requirements more precisely, but it may be difficult to calculate cD for an open frame vehicle. The sweetest conventional IC configuration would probably be a powerplant utilizing B100, or 100% biodiesel. Fuel would, of course, have to be blended during winter season and since B100 is not commonly available, the capability of running conventional petro diesel would be essential for travel in areas where the fuel supply is unknown. It may be possible to incorporate an in-tank electric heating element that permits year-round use of the B100. That would be sweet. 

We believe there are some exceptionally interesting possibilities with regards to ultra lightweight four wheel platforms based on bicycle components. The design issues are not difficult at licensing, registration and insurance issues potentially are. Unlike with their two wheeled and three wheeled counterparts I don't believe the State of Colorado statutes acknowledge a distinction between lightweight and conventional four wheeled vehicles. I should modify that statement. There is a category called neighborhood electric vehicles, NEV, but they are limited to roadway speeds of 35 mph or less. I do not know what the licensing, registration and insurance rules are for this class of vehicle. Does it requires a manufacturer statement of origin simply serial number or some other documentation. 

This raises an issue which may be applicable to any home built vehicle on a Four-wheel platform. Presumably a pedal your ass four-wheel vehicle does not require any special documentation from the State of Colorado. Beneath a certain road speed a two wheel vehicle, even if powered, is exempt from registration. Three wheeled vehicles are subject to the same category divisions as two wheel vehicles. There is an additional distinction made for two and three wheeled vehicles which are limited to 40 mph and, I believe, 4 kW motor or its equivalent internal combustion engine. This class of vehicle must be registered and insured. Presumably, any two or three wheeled vehicle with a higher output power plant or operated on roads at a speed higher than 40 mph fall into the classification of motorcycle. Do state statutes even address multiple classes with regards to four-wheel vehicles? 

What is the state's procedure for licensing and registering a home built vehicle, either two, three or four wheeled ? A related issue is the question of insurance. Typically the state will not issue a registration and license plate unless proof of insurance is provided. I don't know if an insurance company can deal with the vehicle that does not have conventional federal VIN information. Should contact Steve Rumer and see if he can offer any advice regarding home built four-wheel vehicles licensed for road travel. 

Perhaps the primary design issue for the ultra lightweight regards the robustness of construction necessary for this application. I would concede that bicycle components may be too lightweight for a highway speed vehicle, although participants in the Iron Horse Bicycle Classic race pell-mell down a mountain highway at 50+ miles per hour and the bikes don't collapse underneath them. I believe it reasonable to assume that motorcycle grade components would be more than adequate for this application. Besides, wire spoke wheels would look pretty cool on a four-wheeler. The most challenging engineering questions probably regard steering geometry and function. Perhaps downhill racing quad wheelchairs would be a useful source for design ideas. Between bicycle and motorcycle components lie those derived from ATVs. Potential advantage here is the variety of 4WD components available. Transfer cases, selectable lockers and differentials are fairly compact and relatively lightweight, certainly as compared to automotive equivalents. Need to find out if any ATVs use divorced transmissions. It may be that steering and suspension componentry is also suitable for this application, particularly in that ATVs are centerline oriented. It may be possible to scavenge the entire steering of front suspension set from a wide track, competition oriented ATV, and graft them onto a custom tube frame chassis. Perhaps the answer lies some where between ATV componentry and that commonly found on tube framed desert buggies.