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Segway Inventor Designs Hybrid Scooter that will Run on anything that Burns

Dean Kamen is known widely as the inventor of the Segway personal transporter. However, over the past months he has been working on designing a new kind of Hybrid Scooter: A scooter that will make use of a Stirling Engine and be able to run on pretty much anything that will burn.

The Stirling Engine design has been around since the early 1800s. However, few have been able to find a well suited application for the relatively low amount of power they produce. The engine works by using a difference in heat to move a piston inside a sealed chamber. As gas is heated, it will expand and force the piston down. As the gas cools, it will contract and draw the piston back up. While several variants have been created, the one Mr. Kamen plans on using is a simple two-piston design.

The cycle begins with a small amount of heat being applied to the power cylinder. As the gas forces the piston down it turns the crankshaft and produces what would be a power stroke. Once at the bottom of its stroke, the power cylinder begins to rise again, relying on the momentum of the flywheel to maintain rotation. As it rises, it is forcing the gas through a transfer port into the displacer piston chamber. Once inside, the gas is cooled and begins to draw the displacer piston back to the top of its stroke. While this is happening, excess gas is being forced back into the power cylinder through the transfer port. Once the power cylinder has reached the top of its stroke, heat is applied and the cycle repeats.

The main reason for using a Stirling Engine is the simple fact that it is extremely efficient. Depending on the size of the pistons, a relatively small amount of heat can be applied to begin the cycle and often times can be reduced slightly to maintain a certain speed. This is also one of the inherent problems with using a Stirling Engine. They literally have to "warm up" before any usable amount of power can be produced.

Along with needing time to warm up, these engines have a low specific power. In other words, they need to be fairly large to produce a small amount of power. This is primarily due to the speed limitations of gas to transfer heat. When compared to an internal combustion engine that uses detonation to create a difference in heat, Stirling engines are much slower. This also leads to almost nonexistent throttle response if used in an automotive application.

Mr. Kamen was able to solve some of these issues with the simple addition of a battery and an electric motor. The scooter itself uses energy stored in a battery to power an electric motor that is mounted just in front of the rear wheel. The Stirling Engine will be used to turn a high output generator which will produce power for the electric motor. When just cruising around, the engine should be able to crank out enough electrons to keep you moving and keep the batteries fully charged.

A small burner will provide the necessary heat to being the process of turning the Stirling engine, while a front mounted radiator will keep cool air moving for the displacer piston. The burner is being designed to operate on anything that will ignite, which make running out of fuel much more difficult and since the 2 engines are independent of each other, the Stirling engine can be charging the batteries while parked.

The prototype scooter has not yet been demonstrated in public, but it is rumored that Mr. Kamen has been using it to get from place to place on his estate.

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George Delozier
Motorized Innovations
InventorSpot.com

Comments
Jul 14, 2009
by Anonymous

Ahmet

Hi, interesting topic - I have just bought an electric bike that I use to get to work everyday. I Just plug in at work to recharge it and then cycle home.
Absolutely love the bike, it was cheap and simple to use. I got it from www.elecbikeco.com they seemed good but I am sure there are many other companies out there too.
Good luck
Ahmet

Jul 14, 2009
by Anonymous

Mass Produce this

Apply this to other scooters IE Vespa?
Or motorbikes?
Radical.

Be unique.

Id ride one in Hawaii.

Be very Eco friendly & Provide more jobs.

Id love to Rent this & Lease.

Need Hefty engine for higher speeds.

& sidebags for luggage etc.

Neat

Jul 17, 2009
by Anonymous

he's been working on this forever

A Stirling engine is extremely heavy for it's power output, which is why no one has ever put one in a motor vehicle. What Kamen will end up with is an electric scooter with either (1) a very low power generator that may assist in keeping the batteries from running down quite so soon, or (2) if the Stirling engine is powerful enough to add meaningful charge to the batteries, it will be unbearably heavy.

If your object is to get (1), then you would probably be better off using a very small normal gas or diesel engine, which would also give phenomenal fuel mileage. Similarly, if your object is (2) you would probably be also better off with a diesel which would be far lighter and also similarly quite efficient. In either case, the vehicle would be much lighter and far cheaper than anything with a Stirling.

Really the only advantage of the Stirling in this application is that it would be extremely quiet. Being able to run on various fuels is pretty insignificant since gas and diesel are not exactly hard to find.

Here's a real hybrid by a real vehicle company: the new MP3 from Piaggio. It will be a plug in hybrid that will get between 100 and 200 mpg and has a cool three wheel design. Oh yeah, and it will also be for sale.

If, on the other hand, Kamen has somehow invented a phenomenally lightweight, powerful, and efficient Stirling engine, then this idea would make sense. I don't actually think that is the case, which would make this whole exercise a very cool science project but little else.