Dyno Design
Dyno Design
(OP)
Hello,
I'm building a small dyno as a home project for low powered scooters and bikes.
I thinking of coupling the drum with a motor and simply reading the current drawn than using P=IR to find the power.
Or using a car brake with the housing attached to a lever arm and load cell.
Will this work? What size roller will i need? Any comments welcome.
Tim
I'm building a small dyno as a home project for low powered scooters and bikes.
I thinking of coupling the drum with a motor and simply reading the current drawn than using P=IR to find the power.
Or using a car brake with the housing attached to a lever arm and load cell.
Will this work? What size roller will i need? Any comments welcome.
Tim





RE: Dyno Design
The car brake will be a pain, its resistance will change as it heats up.
Cheers
Greg Locock
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RE: Dyno Design
You don't want a motor for your dyno brake (absorber), you want a generator. The dyno needs to put a load on your test article, not drive it.
Whatever type of brake device (electric, friction, hydraulic, etc.) you employ to load your engine, you will need to dissipate the energy absorbed somehow. Getting rid of excess electrical energy (in your garage) would seem to be more expensive and problematic than pumping a supply of water past a restricting valve and measuring the torque reaction about the pump axis. A simple hydraulic brake would also be more tolerant of driveline dynamics than an electric device. These torsional modes always seem to cause problems with IC engines driving dynos. And the first indication of a problem is usually broken dyno parts.
Regardless, it sounds like fun. Just watch your budget. The cost of these "hobbies" can get out of hand quickly!
Good luck.
Terry
RE: Dyno Design
You then need to drive something with the charge produced. A very large array of heating elements could suffice.
Obtaining a correct size DC motor could be a problem.
Regards
Pat
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RE: Dyno Design
With the electric generator, could I simply just run it to a resistor bank (like a regenerative braking system) and measure the current and voltage across that using a multimeter?
Or in terms of the car brake option, to get a reading from the load cell, is all i need to purchase a digital display that the cell can plug into?What would be the best option to measure RPM of the driving shaft, I had a handheld tachometer in mind.
Cheers,
Andy
RE: Dyno Design
- Steve
RE: Dyno Design
This will only work for a very small motor unless you can get a very powerful motor and a big electrical load to absorb the energy.
Regards
Pat
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RE: Dyno Design
Rod
RE: Dyno Design
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Dyno Design
I read Rod's statement as a multi plate wet clutch with centrifugal action.
I guess a lot of oil and a big cooler and short pulls and long recovery times.
Either way, controlling the applied load will be an issue. A multi plate wet disk with a control lever rather than fully centrifugal or a control valve to adjust oil level in the torque converter maybe.
Regards
Pat
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RE: Dyno Design
If you plan on operating over 3400 rpm the generator or pump may have to be belt driven or a very expensive generator acquired. The best accuracy is to measure the shaft torque, next is the reaction torque, last, is the output of the pump or generator. The advantages of a friction brake is low cost, the difficulty is cooling and consistent loading. As a brake warms up the torque will change. With electric or hydraulic the longer you run or the more accurate results, the more important cooling will be.
Ed Danzer
www.danzcoinc.com
www.dehyds.com
RE: Dyno Design
They must be very similar to a fluid coupling. That is like a torque converter without the stator.
RE: Dyno Design
RE: Dyno Design
RE: Dyno Design
They are available in magnetic resistance, viscous and in air resistance. It would probably be easier to adapt one of those to this project. They start at about $100.00 and go up from there, but you don't need the one that connects to your tv and virtually race the tour de franks!!
RE: Dyno Design
RE: Dyno Design
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If we learn from our mistakes I'm getting a great education!
RE: Dyno Design
RE: Dyno Design
All the above reasons are why I use "dyno" figures for comparison only. A small chassis dyno "rolling road" is, for me, an acceptable tool for tuning and/or comparison...not much else. With an assortment of added tools, a dyno run can shortcut the setup of a new race car, thereby saving me mucho bucks. I just do not live and die by the numbers I get.
Rod
RE: Dyno Design
1 motor, 1 cable to the drive from the wall, 1 cable from drive to motor, 1 drive. Simple!
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If we learn from our mistakes I'm getting a great education!
RE: Dyno Design
- Steve
RE: Dyno Design
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If we learn from our mistakes I'm getting a great education!
RE: Dyno Design
RE: Dyno Design
I'm guessing here, but I'd say the entire setup, including the engine was ~100 lbs. I would hazard a guess that a qualified engineer could easily accomplish something along these lines that could function in a repeatable manner without needing to "mortgage" the family home.
Rod
RE: Dyno Design
RE: Dyno Design
http://www.dyno46.com/diydyno.html
Cheers
I don't know anything but the people that do.