Newtons, and Amp-Turns, and Inductance... Oh my..

Oct 22, 2005 7 Replies

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Brent 20 years ago

Hello,

I'm attempting to design a Solenoid that is intended to be able to exert enough pressure to move up to 4.5 Pounds a distance of 0.100 Inches, at a rate of up to 60Hz. The Maximum Height of the Coil is 1.5 Inches, with a Max Outside Diameter of 2.875 Inches, and a Maximum Inside Diameter of 1.5 Inches. The Actuator is a Hollow Cylinder with has the Dimensions of 0.75 Inches in Height, an O.D. of 1.5 Inches, and an I.D. of 1.375 Inches. That is a a wall thickness of 0.125 Inches. The Hollow Cylinder which is the Actuator is 430 Stainless Steel, with a Mass of 0.058 Pounds. This is intended to work in a manner similar to a voice coil in a speaker.

The driver circuit is not a concern at this time. My main focus is the Formulas for determining the Number of Coil Windings needed within the alotted area, for the geometry specified for this Coil.

I've been all over the Web and the newsgroups in an attempt to find the answers. Yet most of what I've discovered deals with transformers, and not Solenoids. In the few post that I've found within the newsgroups that deal with Solenoid Coil Winding, and the physics involved with the construction of such, the Terms used are sometimes left undefined, and frequently the Terms are difficult to read due to the limitations of ASCII notations.

Does anyone have a link, or bookmark to some help webpages, or books that I may purchase, that would help get me up to speed on this subject matter?

Thank you all very much. Brent

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Ian Stirling 20 years ago

You need to elaborate on the magnetic circuit, and other specs. For example, is that 4.5 pounds, and an external spring will provide the return force, or do you need 4.5 pounds push and 4.5 pounds pull.

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Brent 20 years ago

The force is exerted on the upward stroke. There is no spring designed into this solenoid at this time. The Hollow Cylinder will rest on a polycarbonate material inside the bottom of the Coil. The Load encountered by the Actuator will(hopefully) cause / help with the return to the BDC(Bottom Dead Center). I do not know if I have provided enough information. Please let me know if there is anything else needed.

Thank you Sterling, for your reply.

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Dave McDonald 20 years ago

That seems to be a very rare book. The cheapest copy I could find on the net including second hand sources is over $200.

Kind regards Dave McDonald Johannesburg

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Terry Given 20 years ago

Read "Electromagnetic Devices", H.C. Roters, John Wiley & Sons, circa

1950. He covers everything you need to know.

Cheers Terry

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Brent 20 years ago

Terry,

Thank you for the reference to the book. It is truly appreciated.

Brent

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Brent 20 years ago

Dave,

Thank you for taking to time to check this. If this were something that I needed often more than just this one time, I would be able to justify the cost. It may be justifiable if I were too spend too much time in attempting to educate myself, and end up with the wrong formulas, or my mis-interpretation of the science behind this.

Brent

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Rich Grise 20 years ago

Get a bank of big oil-filled capacitors, and make a resonant circuit at 60 Hz. Just drop the actuator into the cup, apply power, and the back emf generated by the eddy currents will make it a LIM.

Good Luck! Rich

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