# Car+ Innovation...pneumatically adjustable twin-wheel hub motor



## Ziggythewiz (May 16, 2010)

Sarit said:


> I am looking suggestions on the technical feasibility and procurement of parts…


I think fairy dust or unicorn blood are your best options.


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## dragonsgate (May 19, 2012)

Sarit said:


> To design the climate-ready car, CAR+ that moves on despite flood, landslides, hurricanes etc., it is necessary to create an innovative wheel system that is immensely useful but affordable. Preliminarily, to develop the 4x4 drive-by-wire transmission for CAR+ (expanding from a 4 seater personal car to 9 seater light commercial vehicle), four in-wheel motors of power 75KW each are proposed. The philosophy is that the wheels should be adjustable to the extent that CAR+ can be pulled by human power. My idea is to develop such adjustable wheel by sandwiching the rotor as well stator between two standard bicycle or bike wheels. Additionally an electric pump can be fitted into the wheel set to adjust the air pressure in the tubes, that is one of the wheels in the set will be taken off the ground touch in order to reduce the effective friction against the driving force.
> I am looking suggestions on the technical feasibility and procurement of parts…
> P.S. more detail on CAR+ is available here: http://www.diyelectriccar.com/forums/showthread.php/want-design-electric-car-can-adapt-87992.html (under Chit chat forum)


Why not build a gyrocopter. When on the ground move it around with the trust of the fan blade. Then when you come to an obstacle like a big bump in the road or a large body of water you just fly over it. As for the expandable wheel base and tracking… how wide and long can you make it? If the vehicle will expand to ten feet wide what are you going to do when you come to a crack that is ten and a half feet wide? This is where the gyrocopter part would be handy. Then you wouldn’t really need the expanding width. If you already have it expanded to max length and all the space is taken up inside and your significant other comes out of the house with an extra suitcase I guess you can bungee it on the roof with the dog. Of course the extra weight with all that junk loaded in the vehicle it might make flying tricky if not impossible. Each of the gadgets you are proposing for this vehicle is going to cause new problems and possibly interfere with each other. Even a Swiss army knife has its limitations.


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## Tesseract (Sep 27, 2008)

You might want to hook up with this guy: The DreamCar123.

Or, perhaps, this guy: The eVette.


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## PStechPaul (May 1, 2012)

I understand your desire to make a vehicle that has many features that would be useful in disaster scenarios, but you should determine the actual payload, top speed, incline handling abilities, etc, before just throwing out a number like 75 kW on each of four wheels. That figure alone makes this project seem like an impractical and frivolous fantasy. That much power may be reasonable for a large truck or drag racer, but for an all-terrain utility vehicle designed to maneuver in a variety of difficult conditions, it seems preposterous. If you wish to be taken seriously, you should first present your baseline specifications of size, weight, payload, range, speed, and energy sources. From that, reasonable estimates could be made on torque and power requirements as well as energy needs.

In-wheel hub motors have been proposed by many and discussed at length on this and other forums, but except for certain heavy equipment and motorcycles, they have not been found to be practical. For one thing, a vehicle designed for adverse conditions would need to operate in the presence of all sorts of things, like sand and water, that would need to be kept out of a motor, and an effective seal is a real challenge.

For human powered towing, you need to consider a lot more than rolling friction of tires, and a very hard tire may be easier to tow on a smooth surface, but very difficult on gravel and uneven ground. Also, the thrust needed for propulsion is the vehicle weight times the percent slope, so a 2000 pound vehicle on a 10% slope requires at least 200 pounds of thrust, which is impossible for a single average human to generate. And also consider the sustained power required to move the vehicle at a certain speed. A human can only supply about 1/2 HP and not for very long.


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## Sarit (Aug 3, 2013)

Hi PStechPaul!
Thanks for your definitive comments. I should admit that pouring into special features without considering the technical feasibility is not right approach for CAR+ innovation. Let do simple check based on available models. 
Drive train:
The most interesting 4x4 wheel electric all terrain model is the Electric Defender from Land Rover. Let take a look into the key specs of Defender.
“ 70kW (94bhp), 330Nm electric motor twinned with a 300-volt, lithium-ion battery with a capacity of 27kWh, giving a range of more than 50 miles. In typical, low speed off-road use it can last for up to eight hours before recharging. The battery can be fully charged by a 7kW fast charger in four hours, or a portable 3kW charger in 10 hours….13 percent gradient and wading to a depth of 800mm…Up to 80 percent of the kinetic energy in the vehicle can be recovered” 
However, CAR+ is aimed to be a predominantly urban car, should car non-urban terrain only in emergency. So, we may compromise with the maximum gradient to travel and consequently the torque of the motor. If anyone looks closely it will be easy to find that the high wading depth for Defender is achieved by road clearance, whereas, CAR+ will float with the chassis sealed by specially designed air bags (will be discussed later).
Now, 75kW driving motor is preliminary thought of based of the available “pre-fabricated electric car conversion set” (PD18 drive) from Protean which essentially and readily available electric drive train based on in-wheel motor (wheel hub motor). The available details (http://www.proteanelectric.com/en/specifications/): 
Peak motor output: 75kW
Average motor output: 54 kW
Peak torque: 1000Nm
Average torque: 700Nm
Input voltage: 200-400 Vdc
This is also applied to convert a 4 WD F150 pickup truck into electric vehicle! So it will be worthwhile to start based on this conversion kit.
Wheel: 
The idea of twin-tire wheel is not actually a fancy one and already employed for convention cars to have better road grip for wet surface [http://www.carbibles.com/ttyreopinion.html]. However, creating a twin-wheel system that also useful for human drive is bit tricky. I admit the power of single human is pretty less to drive CAR+ in emergency without charge, but what about multi-human drive? Here is an example: http://inhabitat.com/human-powered-car-can-go-30-mph-while-driving-uphill/ . The challenge is to create a twin-tire system in which one tyre will be standard thin car tyre or bike tyre and the other (auxiliary) is a standard wheel for “human-powered vehicles”. Here the auxiliary wheel will not be connected in the drive train, rather placed very close to the electric driving wheel to provide greater stability. It is also will be connected to the “human-powered driving chain” system.


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## PStechPaul (May 1, 2012)

Your link to the hub motor has extra characters. It is: http://www.proteanelectric.com/en/specifications/

The specifications seem rather optimistic at 72 HP (54 kW) continuous, for a 68 lb (31 kg) motor. Also note that this is a liquid cooled design, which adds to the complexity and external weight of cooling fluid and pump.

The human-powered car is interesting, but I really doubt the claim of being able to go 30 MPH uphill, no matter how many people are in the vehicle. This is evident by the limitations of the most efficient human-powered conveyance: the bicycle. According to this cool calculator I just found, even the most efficient bicycle with a nearly impossible sustained input power of 250 watts (1/3 HP), on a 5% slope, can only reach 12 MPH.
http://kreuzotter.de/english/espeed.htm

Generally an average healthy human can generate about 200 watts for up to 1 hour, with peak (world record) short-term power 500-1000 watts. 
http://en.wikipedia.org/wiki/Human-powered_transport

Perhaps a better plan would be a modular vehicle where, in a disaster or emergency situation, one or more all-terrain bicycle would be carried with it, and perhaps even use some of the batteries, controllers, and motors of the larger vehicle could be used for individual transportation with a high degree of efficiency and maneuverability.


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## jk1981 (Nov 12, 2010)

If you insist on dreaming up the wildest spec car possible then good luck.

However, my suggestion if you're serious about building something is to pick *one* project of limited scope, get the basics right and maybe add on one or two carefully chosen special features to make the project yours.

For example I bet you could actually make a really good Electric Suzuki SJ 4x4. Maybe with a winch, rear wheel steering, flexible seating/payload (folding out at the rear) for at least 7 as special features. At a push I reckon you could make it float while retaining its on/off road performance (which comes from its low weight). If you retain the gearbox you only need 20 or 30kW to get decent performance which cuts your battery and electrical system requirements massively. That's a realistic project that would be unique yet still useful.


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## Sarit (Aug 3, 2013)

jk1981 said:


> If you insist on dreaming up the wildest spec car possible then good luck.


Thanks for your support jk! I will do it..though it will take some time...

And I would love to share this link of Human-powered car: http://www.humancar.com/ ...if such a power generator available, I don't need to create one  rather will concentrate on regular power-pack for CAR+ will be based on renewable energy sources and captured on-board!

~Sarit


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## Sarit (Aug 3, 2013)

PStechPaul said:


> The specifications seem rather optimistic at 72 HP (54 kW) continuous, for a 68 lb (31 kg) motor. Also note that this is a liquid cooled design, which adds to the complexity and external weight of cooling fluid and pump.


I really need to look into the issue of coolant...can it be done just sucking more air? 



PStechPaul said:


> The human-powered car is interesting, but I really doubt the claim of being able to go 30 MPH uphill, no matter how many people are in the vehicle.


This problem can be solved if the human-power generator of http://www.humancar.com/ really works...of course I have to modify the driving system of it.




PStechPaul said:


> Perhaps a better plan would be a modular vehicle where, in a disaster or emergency situation, one or more all-terrain bicycle would be carried with it, and perhaps even use some of the batteries, controllers, and motors of the larger vehicle could be used for individual transportation with a high degree of efficiency and maneuverability.


I would not prefer to have some sort additional stuff, like, having bicycle on-board to cater emergency situation because in such cases it may not be wise decision to leave the car behind...there should be some way to drive home


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## PStechPaul (May 1, 2012)

The "Human Car" concept is intriguing, and I like the idea of integrating the driver and passenger muscle power as a form of exercise as well as extending the range of an EV. But there is still the limitation of about 200 watts of sustained power from the average human. I was skeptical about the claims for generating enough energy in one hour per day to power even a small refrigerator, but according to the Wiki some small units can run on as little as 500 Wh/day, or a sustained power of about 20 watts. Still, that is more than twice the usual power capability of the average human. The video of the electric guitar and powering the amplifiers does not mean much because even 10 watts is really quite loud.

After further thought about the modular concept I agree that leaving part of the car behind may not be ideal, but that would be for a true emergency situation where only a small hand carriable vehicle could be used. But it may be possible to combine two, four, or more individual two-wheel vehicles into a more capable multi-purpose vehicle. 

It would be a valuable experiment to build a human powered generator using a stationary bicycle or rowing machine and determine just how much peak power you and other test subjects can produce, and how much energy you can provide over an hour to get an idea of what is possible. Here is an article on human power:
http://www.menshealth.com/fitness/human-power-generator

You will also need to figure out how much food the body will need for the effort, and how much body fat can supply. It seems that 500 calories is roughly equivalent to 125 Wh, which is about the same as a 5-6 mile run (or walk - energy is about the same). Then there is the efficiency of the body converting fuel to mechanical power, and if you convert that back to electricity, there are also losses. And if that electricity is used to create mechanical power for a vehicle, there are even more losses. So I would estimate that it might take 1000 calories of food (or body fat) for 125 Wh, and even a very small vehicle (20 kg) with a human rider (80 kg) will need about 250 watts at 20 km/h or 12 MPH, and thus about 20 Wh/mile. So for a 25 mile 2 hour trip you need 500 Wh or 4000 calories of human fuel. I used my http://enginuitysystems.com/EVCalculator.htm to get these figures.


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## Sarit (Aug 3, 2013)

Thanks PStechPaul for the detail review of "human car". I was checking the shaft design for the driving system in "human car". Though it is pretty simple in design, it may not be suitable for the flexible (expandable in both length and width) chassis of CAR+. Rather I will prefer to keep "twin-tire" hub motor wheel system based on Protean electrics PD18 model. These tyres should be of 18 inch motor cycle/ bike wheels with disc radial in the center. In emergency, CAR+ will run with reduced battery power captured from regen-braking system/ bike pedals connected to a generator on-board.

I am looking for a design to accommodate a tiny air pump on each "twin-tire" wheel to adjust the friction from tires (sucking off the air from the inner tire). Obviously the wheel design has to meet minimum requirements of absorbing shocks for a light commercial vehicle, if not for a sedan. A very constructive discussion on hub-motor wheel and its pros/cons is available (with inputs from Representative from Protean Electric) at forum of Tesla motors: http://www.teslamotors.com/forum/forums/why-not-inwheel-hub-engines Please read...


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