Mechanical clutch for downhole tools

An actuation system for a tool, comprising:

• an input shaft;
• a motor coupled to the input shaft for driving rotation of the input shaft;
• an upper armature having an upper engagement structure;
• a drive mechanism for advancing the upper armature axially in response to rotation between the input shaft and the upper armature;
• an anti-rotation guide, with a guide track and a follower moveable along the guide track for guiding relative movement between the upper armature and the anti-rotation guide, the guide track including an axially-extending portion terminating in a circumferential loop;
• a lower armature having a lower engagement structure axially engageable by the upper engagement structure to transfer torque from the upper armature to the lower armature while engaged;
• and
• an output shaft coupled to the lower armature.

A method of transferring torque downhole, comprising:

• powering rotation of an input shaft relative to an upper armature with an upper engagement structure;
• advancing the upper armature axially toward a lower armature with a lower engagement structure in response to the rotation of the input shaft;
• as the upper armature advances, guiding the upper armature axially along an axially-extending portion of a guide track to engage the upper engagement structure with the lower engagement structure and then along a circumferential loop of the guide track to transfer torque from the upper armature to the lower armature via the upper and lower engagement structures;
• and
• driving rotation of an output shaft with the lower armature.