Proportional torque shaft clutch assembly
View Patent ↗A system for securing a cam of a locking mechanism to a rotatable shaft, which comprises a cam for actuating a locking mechanism and a clutch that includes, in part, a sleeve body having a distal end affixed to a face of the cam and a sleeve bore having a tapered sleeve journal and a sleeve screw portion with internal threads opposite the sleeve journal. The clutch also includes a collet that is installed within the sleeve bore and which has a collet nut extending outwardly from a proximal end of the sleeve bore, a collet bore, and an outer surface having an axially-split and tapered collet journal abutting the sleeve journal and a collet screw portion with external threads engaged with the sleeve screw portion. The system further includes a rotatable shaft that is secured within the collet bore with a break-away torque that is proportional to an assembly torque applied to the collet nut. After assembly of the clutch to both the cam and the rotatable shaft, a drive torque applied to the shaft which is less than the break-away torque causes the cam to rotate with the shaft, while a drive torque that is greater than the break-away torque causes the shaft to spin within the collet bore.
1. A system for securing a cam of a locking mechanism to a rotatable shaft, comprising:
a cam for actuating a locking mechanism;
a proportional clutch comprising:
a sleeve body having a distal end affixed to a face of the cam and a sleeve bore comprising:
a tapered sleeve journal; and
a sleeve screw portion with internal threads opposite the sleeve journal;
a collet installed at least partially within the sleeve bore having a collet nut external to the sleeve bore and extending outwardly from a proximal end of the sleeve bore, a collet bore, and an outer surface comprising;
tapered collet journal having an axial split extending through a distal end of the tapered collet journal, said tapered collet journal abutting the sleeve journal; and
a collet screw portion with external threads engaged with the sleeve screw portion; and
a rotatable shaft secured within the collet bore with a break-away torque proportional to an assembly torque applied to the collet nut,
wherein a drive torque applied to the shaft that is less than the break-away torque causes the cam to rotate with the shaft, and a drive torque that is greater than the break-away torque causes the shaft to spin within the collet bore.
2. The system of claim 1 , wherein the assembly torque applied to the collet nut forces the collet journal against the sleeve journal and compresses the axially-split collet bore around the rotatable shaft to create a friction fit between the collet bore and the rotatable shaft proportional to the assembly torque.
3. The system of claim 1 , wherein the tapered sleeve journal is located proximate the distal end of the sleeve bore and adjacent the cam.
4. The system of claim 3 , wherein the sleeve journal and collet journal are tapered inwardly towards a common centerline when traversing from a proximal end to a distal end of the clutch.
5. The system of claim 3 , wherein the collet screw portion is positioned between the collet nut and the collet journal.
6. The system of claim 3 , wherein the applied assembly torque moves the collet inwardly towards the cam and against the sleeve journal.
7. The system of claim 1 , wherein the tapered sleeve journal is located proximate the proximal end of the sleeve bore opposite the cam.
8. The system of claim 7 , wherein the collet journal is positioned between the collet nut and the collet screw portion.
9. The system of claim 7 , wherein the applied assembly torque moves the collet outwardly away from the cam and against the sleeve journal.
10. The system of claim 7 , wherein the sleeve journal and collet journal are tapered outwardly away from a common centerline when traversing from a proximal end to a distal end of the clutch.
11. The system of claim 1 , further comprising a clutch aperture through the cam for receiving the distal end of the sleeve body therein.
12. The system of claim 11 , wherein the rotatable shaft is inserted into the collet bore from a side of the cam opposite the proportional clutch.
13. The system of claim 1 , further comprising a threaded opening through a sidewall of the sleeve body and configured to receive a set screw therein for locking the collet in a rotational position within the sleeve bore.
14. A system for securing a cam of a locking mechanism to a rotatable shaft, comprising:
a cam for actuating a locking mechanism;
a proportional clutch comprising:
a sleeve body having a distal end affixed to a face of the cam and a sleeve bore comprising:
a tapered sleeve journal adjacent the cam; and
a sleeve screw portion with internal threads opposite the sleeve journal;
a threaded collet inserted at least partially within the sleeve bore having a collet bore and an outer surface comprising:
tapered collet journal having an axial split extending through a distal end of the tapered collet journal, said tapered collet journal abutting the sleeve journal;
a collet nut opposite the collet journal external to and extending outwardly from a proximal end of the sleeve bore; and
a collet screw portion with external threads between the collet nut and the collet journal and engaged with the sleeve screw portion; and
a rotatable shaft secured within the collet bore with a break-away torque proportional to an assembly torque applied to the collet nut, and
wherein a drive torque applied to the shaft that is less than the break-away torque causes the cam to rotate with the shaft, and a drive torque that is greater than the break-away torque causes the shaft to spin within the collet bore.
15. The system of claim 14 , wherein the rotatable shaft is inserted into the collet bore from a side of the cam opposite the proportional clutch.
16. The system of claim 14 , wherein the sleeve journal and collet journal are tapered inwardly towards a common centerline when traversing from the proximal end to the distal end of the clutch.
17. The system of claim 14 , further comprising a threaded opening through a sidewall of the sleeve body and configured to receive a set screw therein for locking the collet to a rotational position within the sleeve bore.
18. A method for securing a cam of a locking mechanism to a rotatable shaft, comprising:
affixing a distal end of a sleeve body to a face of the cam, the sleeve body having a sleeve bore including:
a tapered sleeve journal; and
a sleeve screw portion with internal threads opposite the sleeve journal;
installing a collet into the sleeve bore, the collet having a collet nut being external to and extending outwardly from a proximal end of the sleeve bore, a collet bore, and an outer surface including:
tapered collet journal having an axial split extending through a distal end of the tapered collet journal, said tapered collet journal abutting the sleeve journal; and
a collet screw portion with external threads engaged with the sleeve screw portion;
inserting a rotatable shaft into the collet bore; and
applying an assembly torque to the collet nut and securing the collet to the sleeve body and the rotatable shaft to the collet with a break-away torque proportional to the assembly torque,
wherein a drive torque applied to the shaft that is less than the break-away torque causes the cam to rotate with the shaft, and a drive torque that is greater than the break-away torque causes the shaft to spin within the collet bore.
19. The method of claim 18 , further comprising tightening a set screw installed in a threaded opening through a sidewall of the sleeve and locking the collet in a rotational position within the sleeve.
20. The method of claim 18 , wherein the rotatable shaft is inserted into the collet bore from a side of the cam opposite the proportional clutch.