Unique Torque Converter Application 1

[WesleyGarner]

I have a patent pending on an idea which uses a torque converter on a bicycle as described below. Before you dismiss this immediately, please understand that 15 million bicycles are sold each year in the U. S. and there has been no significant development in bicycle design since the derailleur was introduced half a century ago.

If the torque generated by the rider is applied to the rear wheel of the bicycle through a torque converter, the torque multiplication mimics the gear shifting of a multi-speed bicycle. I am not aware of any design obstacles that cannot be overcome to make this work. Do you? Is there a fatal flaw? Who can provide assistance in designing and fabricating a prototype?

 

[GregLocock]

Why don't you check out the operating characteristics of practical torque converters? Things like efficiency and operating speed. And weight.



Cheers

Greg Locock

 

[Warpspeed]

Efficiency worries me too. A CVT of some sort might be the answer ?

 

[WesleyGarner]

Warpspeed,

Thank you very much for your posting. I have been in the cycling industry for over 10 years (from racing to managing a bicycle shop). From my experience, most people are overwhelmed with 6, 21 (or more) speed bicycles and waste energy because they don't understand when or how to shift. I think the efficiency loss in a torque converter is most likely less than the loss in current, multi-speed bicycles because of the lack of skill of the average rider. I also think that, if the torque converter works as I think it will, the riding experience will be wonderful- it simply gets easy to pedal when one attemtps to accelerate or when one encounters resistance (hills or headwinds). If this is the case, most riders would gladly make the trade-off. Based on this, would you please elaborate on your concerns about efficiencies. Thanks again for your response.

 

[Warpspeed]

I used to do a fair bit of cycling in my youth, but that was a very long time ago. As I understand it there is a fairly narrow comfortable speed range at which you can peddle and develop useful sustained power output.

At one time I could just generate half a horsepower for five minutes on an exercise bike. Not these days though !

As you say the average recreational rider is just not up to changing gears in any sort of logical or efficient manner. Competitive riders MUST master this technique.

A torque converter would definitely be an advantage for a novice rider, but from the mechanical engineering point of view it is just not energy efficient. There are unfortunately tradeoffs between slip rate, torque multiplication and power loss in a torque converter.

If you could develop a constantly variable speed transmission (CVT) without slip, and minimal power loss, it would be ideal. These things already exist, they usually consist of a friction drive between some steel balls and cones or discs, or hydraulic, and they can reliably transmit many horsepower over a speed range of at least 10:1

Another method is a drive belt that transmits power between two variable diameter pulleys. Each pulley consists of two facing cones. By moving the two cone halves together or apart, the belt rides higher or lower on each pulley.

A third method would be a variable stroke swash plate hydraulic pump and hydraulic motor. That might be the most fruitful line of experimentation. Fit the pump between the pedals, and build the motor into the rear hub. No chain required! The cyclists will love you.

The actual variable speed mechanism could be made fairly small and compact if it could run at relatively high speed and low torque. Half a horsepower is not a lot, but exactly how to design it I have no idea.

It is a good idea though, and someone will eventually do it I am sure.

 

[shbazjinkens]

People have been experiementing with CVTs in bikes for a while.

One example (I'm not affilliated):
[link]http://www.varispeed.com/media.htm[/url]

Seems like that one is a toroid, though I can't be sure.

 

[WesleyGarner]

Thanks for posting. I visited the site for more information and found that the design is not hydraulic. A torque converter is hydraulic by default...correct? That should make my design different.

 

[cyclelaboratories]

There is a comany that developed an infinitely variable hydraulic transmission specifically for bicycles, the company was called powercurve technologies. I have been trying to develop a similar device for a cycle concept I am working on.

http://www.powerengine.com/aitx001hydbiksum.htm

It is a great design, but the comany/patent holders are impossible to reach.