# Reciprocating solenoid motors and other alternative designs



## PStechPaul (May 1, 2012)

I've been fascinated by motor design and I have some ideas I want to to try for alternate designs. I was thinking about emulating a piston type ICE using electrical solenoids, and I found some really beautiful designs:





 




 




 




 
I don't know if they have any practical use in EVs but they are really cool looking and I'm thinking about building one. Probably a three-solenoid radial.


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## Salty9 (Jul 13, 2009)

Interesting motors. I've been following http://www.rcgroups.com/ornithopters-101/ 

Where I think linear motors could be used in place of rotory motors and their associated gearing.


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## PStechPaul (May 1, 2012)

My idea is to use an electromagnetic linear actuator which might be designed using simple solenoids and a ferromagnetic core:
http://www.scs-europe.net/conf/ecms2009/ecms2009 CD/ecms2009 accepted papers/eee_0022_4d5d6081.pdf

Or possibly a linear induction motor similar to this:
http://www.h2wtech.com/Pages/AC-Linear-Induction-Motors.aspx

It is capable of a force of 650 pounds which would translate to a torque of 300 lb-ft on a 12" diameter wheel. It can move at up to 350 inches per second so for the same wheel that is 557 RPM. This works out to 32 HP. It is actually 185 amps peak at 400 VAC which is 128kW or 170 HP. So either it's very inefficient or I've calculated wrong. This thing weight 420 lb so that's about right for a 32 HP motor, but this is peak so the weight is more in line with the 170 HP peak or about 50 HP continuous.

One cool thing about a reciprocating motor is that you can change the torque and speed by moving the crankshaft point in and out from the center. It's an interesting concept since the linear velocity is determined by the drive frequency, but it would have to be modulated as it moved around the driveshaft and reversed every half-revolution.

It might be best to adjust the spacing of the stator to compensate for the change of linear speed along the stroke. Then a fixed frequency could be used and it would only need to be reversed at the end of stroke.


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