Latch activation between members
Described herein is a system, method of use and Self Retracting Lifeline (SRL) apparatus using a system that governs a dynamic response between members causing a halt in relative motion between the members. Magnetic interactions, eddy current drag forces and centrifugal and/or inertial forces may provide various mechanisms of governing movement.
1. A self-retracting lifeline comprising:
a coupler configured to selectively couple a spool with line thereon to a latch on an external member, and in doing so slow or halt relative motion between the spool and line thereon and the external member;
wherein the coupler includes a pawl linked to and rotating with the spool when line on the spool is withdrawn from the spool;
wherein, when the spool rotates due to line withdrawal from the spool below a velocity and acceleration threshold, the pawl oscillates radially outward and inward relative to the spool axis of rotation and the coupler does not couple the spool to the external member; and
when the spool rotates due to line withdrawal from the spool above a velocity and acceleration threshold, the pawl of the coupler moves radially outward sufficiently far to a deployed position such that the pawl or a part thereof engages a geometric latching interface on the external member thereby coupling the external member and spool and in doing so halting relative motion between the external member and spool.
2. The self-retracting lifeline of claim 1 wherein the pawl is directly linked to the spool.
3. The self-retracting lifeline of claim 1 wherein the pawl is indirectly linked to the spool.
4. The self-retracting lifeline of claim 1 wherein the pawl is biased to an uncoupled position.
5. The self-retracting lifeline of claim 4 wherein the bias is a spring.
6. The self-retracting lifeline of claim 1 wherein the coupler comprises two pawls, both pawls rotating with the spool.
7. The self-retracting lifeline of claim 1 wherein the external member geometric latching interface comprises a tooth.
8. The self-retracting lifeline of claim 7 wherein the external member comprises at least two teeth.
9. The self-retracting lifeline of claim 1 wherein a distal end of the pawl engages the geometric latching interface.
10. The self-retracting lifeline of claim 1 where in the external member geometric latching interface is shaped as a ratchet so that once coupled, the spool can only move in a reverse direction to wind line onto the spool and line cannot be drawn from the spool.
11. The self-retracting lifeline of claim 1 wherein the pawl velocity sensitivity is tuned to permit oscillation by balancing the centrifugal force imposed on the pawl to move outwards with an opposite bias force moving the pawl inwards.
12. The self-retracting lifeline of claim 1 where in the pawl acceleration sensitivity is tuned by balancing the pawl inertia to movement caused by a centrifugal force outward against the rate of change in spool rotation.
13. The self-retracting lifeline of claim 1 wherein the external member is a housing around the spool or a part thereof.
14. The self-retracting lifeline of claim 1 wherein the external member is a further member and the spool rotates within the further member.
15. The self-retracting lifeline of claim 1 wherein the pawl has an axis of rotation, the pawl axis of rotation located offset from the spool axis of rotation.
16. The self-retracting lifeline of claim 1 wherein the pawl is an elongated member with a first end linked to the spool and an opposing second end, on coupling, latching with the external member.
17. The self-retracting lifeline of claim 16 wherein the pawl at the first end is indirectly linked to the spool.
18. The self-retracting lifeline of claim 1 wherein the pawl remains coupled to the external member while the spool velocity and acceleration remain above the velocity and acceleration threshold; and decoupling occurs when the spool velocity and acceleration lowers below the velocity and acceleration threshold.
19. The self-retracting lifeline of claim 1 wherein the external member is a peripheral energy absorber that slows or halts relative motion between the spool and external member.
20. The self-retracting lifeline of claim 1 wherein the halting of relative motion between the external member and spool results in zero absolute velocity of the spool and line withdrawal from the spool.