Quote:
Originally Posted by Arragonis
How do you measure torque, how does a torque sensor work and how does it work in an engine ?
(P.S. I'm not trolling, I really want to know)
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There are different mechanisms that can be used to achieve the result of torque measurement.
Just there are different mechanisms that allow you to measure temperature... or light... or weight ... etc.
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Without getting too crazy about it.
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#1> One type of common torque mechanism exploited in many sensors is the spring rate of a specific material.
If you know that a specific calibrated device will 'deflect' a specific known amount under a specific amount of torque ... than you can later use that deflection in order to deduce the torque.
For example a section of the metal drive shaft. When you put the metal under a load it will flex. This happens weather the load is at any right angle to the shaft or if the load is in a rotational direction about the shaft.
Many metals have a point of bending that does not deform the metal, it bends under the load but down not retain that bend when the load is removed. This effect is used by all metal springs. The load compresses the spring, but it does not permanently deform the spring. ... your non-digital bathroom scale uses this to measure the load you apply to it... so does some torque wrenches.
~2 years ago I was quoted $9,000 to measure the rotational torque deflection of the OEM drive shaft ... which could then be used as a basis to make a sensor to real time measure the torque for anyone's Gen-1 Insight OEM drive shaft.
~2 years ago I was also quoted $12,000 to alter an existing drive shaft to include a pre-made and calibrated sensor to do that shaft torque measurement function.
I'm hoping the price will come down, by the time I finish other projects.
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#2> Although less common ... When the deflection is too small to get meaningful measurements from directly ... Other means can be used to measure the other effects ... be they pizeo-electric effects ... changes in resistance ... changes in magnetic flux , and fields .... etc.
Those other mechanisms exploit the fact that material under load have slightly different properties then when not under a load.
As long as the effects on the material under load can be quantified you can then make a sensor to measure it... some digital scales make use of this kind of mechanism for their sensors.
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Forgot to include before:
If you have a more common type of car ... there are lower cost ... at least less than the $9k options than what I previously wrote about above.
Shaft
Wheel