New type of braking system

I had an idea about using a strong coiled band spring, like a watch spring, for the braking system on a bicycle. When the brake is applied, the outside of the coil connects to the wheel and the spring winds up as the wheel slows down. When the bike comes to a stop, it locks in place to prevent the spring from pushing the bike backwards. Now, the coasting energy is stored in the coiled spring. The center of the coil is attached to a sprocket that is attached to the wheel. When the brake is released, the coiled spring unwinds turning this center sprocket in the forward direction which also turns the bike's wheel in the forward direction. So, the coasting energy that the bike had before stopping is being used by the spring to push the bike in the forward direction when the bike starts up again. When the spring unwinds completely, the wheel continues to turn forward wratcheting past the center sprocket; the wheel turns free of the center sprocket.
If this can be made to work for a bike, it might be possible to make it work for motorcycles and small cars.
I consider this a metalurgy and mechanical enineering problem, which could be resolved by trial and error and experimentation. The right connections must be found and the right type of metal for the spring. Fixing the brakes might just involve installing a new spring.

 

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for starters a bendix coaster brake is a relatively simple device
next, they practically never fail

for your idea to have merit, especially for braking systems, it must satisfy both of the above.

 

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Sounds promising. A good high-quality steel used for ordinary springs might just fit the bill - except that the number of winds must be very large.

 

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I have not tried to calculate, but doubt a steel spring that fits inside the wheel can store the energy of 200lbs (man and bike) moving at 25 miles / hour. It probably weighs at least 50 lbs, so make that 250lbs moving at 25mph.

 

The stopwatch is ticking. You have less than a year to file a patent application or else then nobody can get a patent on it.

 

Sounds overly complicated to store such a small amount of energy. Also, how does this system cope with gentle braking? Say you are travelling down a long incline, and applying the brakes to maintain a constant, safe speed. Surely, at some point, the spring will become fully wound, what do you do then? Will the wheel lock, and bring you to a sudden stop, or will it try and unwind, acclerating you? Or do we have two sets of brakes, or some braking/release mechanism on the spring/hub?

 

Us critics are pointing out a dire need for this venture. The inventor must calculate the maximal energy density for a state of the art spring energy storage system and compare it with alternative regenerative braking systems, on a pound for pound, and other important basises(?), and determine if it is competetive.

The free market competitive system is viciously dog eat dog. May the best system win.

 

Or, he could just ask people if they would be interested in buying such a system, and save himself the time.

I ride a bike a fair amount, and I'm not interested in recouping the energy lost in braking with a complicated system of springs, gearboxes, and slip rings that I'll have to keep clean, lest they suffer a failure while I'm travelling at 30mph downhill.

 

Not even a spiral spring?

 

That was the type I had in mind. Pehaps 2mm thick, on average, by 2cm wide and many meters long and when fully relaxed, straight for those "many meters."
Actually the end attacted to the hub would have such small radius of curvature that it could only be small part of 1mm thick.

Spring would probably cost more than a cheap bike to make. I am almost sure for less cost, a lighter bike would be easier to use as I still doubt much energy can be stored. - Certainly not the full braking down a long hill and once at the valley bottom, that stored eneergy will take you up only a small fraction of the hill on the other side.

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- after that the extra energy required to lift the heavy spring up to top of next hill comes from you.

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Perhaps in Denmark, but not in West Virgina, the idea might be ok, but in flat land, who needs it? I.e. don't bother to send me announcement of the company's IPO.

 

It can't work properly because you wouldn't have instantaneous braking with the coil spring mechanism. With a vehicle on the road, you need to be able to apply the brakes instantly - with no winding of a spring.

 

Fraggle is right. The problem is that riders might experience too sudden of a braking with a coil spring mechanism.

Suppose F=(-)kx. When the spring constant is high, then we see a large slope on a graph of F vs. delta x. In order to minimize the difference in force, which linearly translates to acceleration, then one must consider a small difference in the spring displacement. But in order to provide sufficient energy to the mechanism, one needs to consider a small difference at someplace far up from the rest position of the spring, since the integral under the line is the energy taken from the bike and stored. Luckily, one finds many many types steel that never relaxe nor fatigue with time for well over 50% of their elastic regimes, so you can start in a highly stressed position and end in a slightly higher stressed position for a small increment in length - but one needs to use a fantastic gear mechanism and a stop mechanism (to prevent overstressing and therefore impending cyclic fatigue) in order to exploit this successfully.

 

I have a question : how much does a car's shock absorber (the large helical spring found directly above the wheels) cost? Certainly a spring of that much k should be many times more expensive or heavy than one that gets put on a bike. Spring steels are actually one of the highest quality alloys found, apart from maraging steel, surgical steels, and titanium alloys, so I'm not disputing the fact that it would definitely cost more than just a lump of metal.

 

I thought about the system a little further. When the wheel comes to a stop, you don't need the wheel to lock. You need the outside of the spring that was attached to the wheel, when the brake was applied, to attach itself to the frame of the vehicle. This prevents the spring from unwinding and pushing the bike backwards, and it will allow it to unwind in the forward direcion, on the center sprocket, when you want to move forward again.

 

its not a horrible idea (not great either), but nobody will buy it.

 

As Facial and Fraggle allude to, the problem is that the spring would somehow have to be variably applied and not continuously locked to the wheel when the brake is applied, or else somehow you have a variable tension spring to control the braking. It can't be just an either or event.

 

That won't work will it? Think, ......

 

I'm thinking about a spring positioned near the center of the wheel, on the inside of the wheel rods.

 

doesn't seem needed so I am not sure of its marketability