Electro-mechanical device and associated method of assembly

An electro-mechanical device, comprising:

• an electromagnetic coil;
• and
• an armature selectively movable between an engaged position and a disengaged position, the armature being engaged with the electromagnetic coil in the engaged position and defining an air gap between the electromagnetic coil and the armature in the disengaged position,
• wherein a size of the air gap is set to be within a desired range by a method comprising:
• (i) applying a sensing signal to the electromagnetic coil;
• (ii) monitoring at least one electrical characteristic of the electromagnetic coil, the at least one electrical characteristic being related to a size of the air gap and the sensing signal;
• (iii) moving the armature towards the electromagnetic coil to reduce the size of the air gap;
• and
• (iv) stopping movement of the armature towards the electromagnetic coil when the at least one electrical characteristic indicates the size of the air gap is within the desired range.

A method of setting an air gap between an electromagnetic coil and an armature of an electro-mechanical device to be within a desired range, the method comprising:

• applying an alternating current voltage signal to the electromagnetic coil;
• monitoring a first current drawn by the electromagnetic coil based on the alternating current voltage signal;
• moving the armature towards the electromagnetic coil to reduce the size of the air gap;
• determining a first current threshold, the first current threshold being related to the size of the air gap being within the desired range;
• comparing the first current drawn by the electromagnetic coil to the first current threshold;
• determining that the size of the air gap is within the desired range when the first current drawn is below the first current threshold;
• stopping movement of the armature towards the electromagnetic coil when the size of the air gap is within the desired range;
• confirming that the size of the air gap is within the desired range by:
• (i) applying a direct current voltage signal to the electromagnetic coil and (ii) detecting a change in a second current drawn by the electromagnetic coil based on the direct current voltage signal.