Big Wheel EV [EVWorld.com]
Side view illustration of Pal¹s patent-pending wheel-car concept in which the driver and passenger ride inside the axle.

Thinking Outside the Box

A description of a radically different type of personal mobility device.

By Anadish K. Pal

Editor's Note: Anadish K. Pal lives in India and took the expression "thinking outside the box" literally. While his command of English is a bit awkward at times, we at EV World find this kind of thinking refreshing, even if it might seem a bit outlandish. If GM can propose fuel cell-powered "skateboards" for their Autonomy concept vehicle, why not battery-powered, big wheels?"

Any technological challenge is looked at differently by people from different streams. Transportation could be alternation of generation for a biologist; a virtual movement for an IT person; a sub-atomic shaping up for a physicist.

What it could be for an electronics enthusiast?

This question used to gnaw at me for the past ten-or-so years. A modern-day car has too many mechanical parts for comfort. Then there is combustion, there is computing, there are pneumatics, there are hydraulics. An electronics engineer would like to have a Lego-like electrical car -- where there are all electronics and [fewer] stone-age mechanicals.

How could there be a truly electrical car?

The problem always persisted. All the solutions seemed to be mainly mechanical contraptions with the electrical motor replacing the engine. To a person belonging to electronics, it was always a discomforting idea. It was like removing the horses from a stage carriage, and putting a small engine below your seat -- like they did in l880s and 90s.

In December 1996, one late evening, watching newly-manufactured cars being driven away at a car manufacturer's yard, it struck me: Why not have a person sit inside a large wheel? And then things seemed to be falling into place.

Hurriedly I constructed toy-like models to check the braking ability of the design. And when it was found okay, it started looking encouraging.

I applied for a Provisional US Patent on 4 February 2000 (USPTO Provisional Application No.60/182,772 of 4 Feb.2000). Business with my existing work of power-electronics design, lack of knowledge about US patenting, and a characteristic Indian sluggishness could be ascribed for the delay in applying for a patent. Anyway mechanical drawings were not my forte.

A quick look at the internal side view would make the basics clear.

It's a two-wheel electric vehicle where wheels are parallel to each other -- the title of my provisional application. There are two ring-like brushless DC motors, of 50 inches-or-more diameter. The rim of the wheel is 6 to 7 inches radially. This way the axle measures say 50 inches, and the rim of the wheel just 7 inches. The axle is hollow and the passengers fit inside of it.

The position of the Lead-acid batteries (4 Nos. of 200AH 12V), is below the passenger seats, which is the key to the stability of the design. This brings the centre of gravity below the geometrical centre of the axle. At the time of braking at high speeds, the forward momentum of the batteries counters the braking torque.

There are distinct advantages to this approach. The straight line, which forms at the place the wheel comes into road contact, produces less distortion in a large-diameter wheel as compared to a comparatively smaller-diameter wheel carrying the same payload. This advantage makes this EV easier to roll, needing less traction power. The estimated weight of this vehicle is around 700kgs including the weight of two passengers.

The motors have rare-earth permanent-magnet rotor on the rim, and the 180-pole stator is wound with aluminium-enamelled wire to reduce weight. The motor voltage is 24V.The batteries have vapour chambers connected to each cell, which contain the evaporating electrolyte and effect recombination. This makes normal Lead-acid batteries suitable for traction duty without the need for water topping up.

This EV does not have any mechanical brakes, neither any mechanical steering. It is an inherently stable vehicle, as opposed to Dean Kamen's Segway. The position of the passengers inside the annular motors, safeguards against damage from impact. Otherwise also, the barrel-like construction makes the shell very strong -- reminds you of those fun-loving New Zealanders rolling inside giant barrel cages.

I am planning to build a life-size prototype. Though financially it would be difficult for me to continue the developmental work, still, I hope to complete the first working model in a few months' time. Beyond that I might have to look out for sponsors. The USPTO plans to publish my non-provisional application sometime in July this year.

Right now I am also working on couple of transport designs which are not EVs, but are very interesting.

Times Article Viewed: 9300
Published: 05-May-2002


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