Solenoid, armature length

Discussion in 'Mathematics and Physics' started by ccurtis, Nov 9, 2017.

1. ccurtisActive Member

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It is well established that the axial force on a solenoid armature is an inverse, exponential function of the distance that the armature protrudes from the coil. This is because of the air gap that exists and changes with that distance.

So, I'm wondering if I make the armature longer than the coil length, protruding out both ends of the coil, but offset from center, does that helps to increase the initial force on the armature since the armature always fills the hole in the coil (no air gap) and the force seeks to center the armature?

2. shortbus=Well-Known Member

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Would an armature like that even move? An armature that is all ready in the coil would only become magnetized wouldn't it?

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I think the armature will tend to centralise itself in the energised coil, so that the push-pull effects of the protruding parts will cancel each other out.

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5. shortbus=Well-Known Member

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I may have misunderstood the description, but I took it as the armature was already centralized in the coil, with equal lengths extending out of the coil.

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The OP says "offset from center".

7. shortbus=Well-Known Member

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But in that same sentence he says, "So, I'm wondering if I make the armature longer than the coil length, protruding out both ends of the coil"