Threaded fastener
A threaded fastener includes a nut forming a threaded center hole that defines a rotational axis. The threaded fastener also includes a plurality of spring plungers affixed to the nut, each having a shaft that is aligned parallel to the rotational axis. The threaded fastener also includes a positioner forming (i) an unthreaded center hole that is coaxial with the threaded center hole and (ii) a plurality of recesses facing the spring plungers. As the nut is torqued against the positioner on a threaded spindle, the spring plungers repeatedly engage and disengage the recesses as the nut rotates with respect to the positioner. The recesses are shaped such that positioner converts the applied torque into a linear force that compresses the spring plungers, thereby locking the threads of the nut against the threads of the spindle.
1. A threaded fastener comprising:
a nut forming a threaded center hole that defines a rotational axis of the threaded fastener;
a plurality of spring plungers affixed to the nut, each of the plurality of spring plungers including a ball-shaped contact movable along a shaft aligned parallel to the rotational axis; and
a positioner forming (i) an unthreaded center hole that is coaxial with the threaded center hole and (ii) a plurality of recesses uniformly spaced around the rotational axis and facing the plurality of spring plungers, each of the plurality of recesses being shaped to engage with the ball-shaped contact;
wherein the plurality of spring plungers are angularly spaced about the rotational axis such that each spring plunger alternately engages with a recess and the plurality of recesses and the plurality of spring plungers cooperate to create a ball detent mechanism such that, in response to an applied torque being applied to the nut:
the ball-shaped contact of one of the plurality of spring plungers engages with one of the plurality of recesses; and
the ball-shaped contact of said one of the plurality of plungers disengages with said one of the plurality recesses when the applied torque exceeds a minimum torque.
2. The threaded fastener of claim 1 , each of the plurality of spring plungers including a spring that exerts an axial force against the ball-shaped contact to push the contact against the positioner.
3. The threaded fastener of claim 1 , wherein:
the nut forms a plurality of plunger mounting holes surrounding the threaded center hole; and
each of the plurality of spring plungers is inserted into a respective one of the plurality of plunger mounting holes.
4. The threaded fastener of claim 3 , the plurality of plunger mounting holes being centered at the same radius from the rotational axis.
5. The threaded fastener of claim 4 , the plurality of plunger mounting holes being uniformly spaced about the rotational axis.
6. The threaded fastener of claim 4 , the plurality of recesses being centered at the same radius from the rotational axis.
7. The threaded fastener of claim 6 , the plurality of recesses being uniformly spaced about the rotational axis.
8. The threaded fastener of claim 1 , the nut being shaped as a polygon.
9. The threaded fastener of claim 8 , each of the plurality of spring plungers being located at a respective corner of the nut.
10. The threaded fastener of claim 8 , the polygon being a regular hexagon.
11. The threaded fastener of claim 1 , wherein:
the threaded fastener further comprises a retaining ring that encircles the nut about the rotational axis;
the positioner comprises:
a disc forming the unthreaded center hole and the plurality of recesses; and
a lip extending axially upward from an outer edge of the disc and forming indentations that extend radially inward from the outer edge; and
the indentations cooperate with the retaining ring to axially constrain the positioner relative to the nut.
12. The threaded fastener of claim 11 , the retaining ring comprising a flange integrally formed with the nut and extending radially outwards from outer-facing surfaces of the nut.
13. The threaded fastener of claim 11 , the retaining ring comprising an annulus inserted into a plurality of notches, formed in outer-facing surfaces of the nut, that axially constrain the annulus.
14. The threaded fastener of claim 11 , the disc forming a tab that engages with a slot of a threaded spindle to rotationally constrain the positioner relative to the threaded spindle.
15. The threaded fastener of claim 11 , each of the plurality of recesses being one of a countersunk hole, a counterbored hole, and a straight through-hole.
16. The threaded fastener of claim 1 , wherein:
the plurality of spring plungers are uniformly spaced about the rotational axis by a plunger angular spacing;
the plurality of recesses are uniformly spaced about the rotational axis by a recess angular spacing; and
the plunger angular spacing is not an integer multiple of the recess angular spacing.
17. The threaded fastener of claim 1 , wherein:
the plurality of spring plungers are uniformly spaced about the rotational axis; and
the plurality of recesses are uniformly spaced about the rotational axis.
18. The threaded fastener of claim 17 , wherein a number of the plurality of recesses is not an integer multiple of a number of the plurality of spring plungers.
19. A threaded fastener, comprising:
a nut forming a threaded center hole that defines a rotational axis of the threaded fastener;
a plurality of spring plungers affixed to the nut, each of the plurality of spring plungers including a shaft that is aligned parallel to the rotational axis; and
a wire forming:
at least part of a loop that encircles the rotational axis, the loop creating an unthreaded center hole that is coaxial with the threaded center hole; and
a plurality of radial undulations that create a plurality of recesses facing the plurality of spring plungers;
wherein, in response to an applied torque being applied to the nut:
one of the plurality of spring plungers engages with one of the plurality of recesses; and
said one of the plurality of recesses is shaped to disengage said one of the plurality of spring plungers when the applied torque exceeds a minimum torque.
20. The threaded fastener of claim 19 , wherein:
the nut includes a lip that extends circumferentially around the threaded center hole, extends axially away from a top face of the nut, and has a radially inward-facing surface that forms a circumferential gap; and
the threaded fastener further includes a retaining ring inserted into the circumferential gap to axially constrain the wire relative to the top face of the nut.
21. The threaded fastener of claim 19 , the wire having a first end extending radially inward to form a tab that engages with a slot of a threaded spindle to rotationally constrain the wire relative to the threaded spindle.