Setback switch for safe and arm
A switch mechanism is provided that has a tubular enclosure; a contact pin electrically insulated from the tubular enclosure; a g-weight positioned inside the tubular enclosure and movable from an open position to a closed position; and a transparent closure that encloses one end of the tubular enclosure. The g-weight is in electrical contact with the contact pin and the tubular enclosure when the g-weight is in the closed position, such that a continuous electrical path exists from the contact pin to the tubular enclosure. The g-weight is for moving from the open position to the closed position when the switch mechanism is subjected to an acceleration greater than a threshold acceleration. The g-weight is visible through the transparent closure such that the position of the g-weight can be determined without removing the transparent closure from the tubular enclosure.
1. A switch mechanism, comprising:
a tubular enclosure;
a contact pin electrically insulated from the tubular enclosure;
a g-weight positioned inside the tubular enclosure and movable from an open position to a closed position; and
a transparent closure that encloses one end of the tubular enclosure,
wherein the g-weight is in electrical contact with the contact pin and the tubular enclosure when the g-weight is in the closed position, such that a continuous electrical path exists from the contact pin to the tubular enclosure,
the g-weight is for moving from the open position to the closed position when the switch mechanism is subjected to an acceleration greater than a threshold acceleration, and
the g-weight is visible through the transparent closure such that the position of the g-weight can be determined without removing the transparent closure from the tubular enclosure.
2. The mechanism of claim 1 , wherein the contact pin is a tapered contact pin.
3. The mechanism of claim 2 , further comprising at least one breakable member attached to the g-weight, the breakable member
holding the g-weight in the open position when subjected to an acceleration less than the threshold acceleration, and
being for breaking and allowing the g-weight to travel from the open position to the closed position when subjected to an acceleration greater than the threshold acceleration.
4. The mechanism of claim 3 , wherein the at least one breakable member comprises two breakable members that extend radially from the g-weight and each engage a corresponding recess in the tubular enclosure.
5. The mechanism of claim 4 , wherein the g-weight comprises a plurality of petals that electrically contacts the tubular enclosure and the contact pin when the g-weight is in the closed position,
the petals are wedged between the tubular enclosure and the contact pin when the g-weight is in the closed position, and
the g-weight further comprises a tapered void for receiving the contact pin when the g-weight is in the closed position.
6. The mechanism of claim 1 , further comprising a housing wire that is electrically connected to the tubular enclosure and is for electrically connecting to a printed circuit board to which the switch mechanism is to be mounted.
7. The mechanism of claim 1 , further comprising a terminal lug that is electrically connected to the contact pin and is for electrically connecting to a printed circuit board to which the switch mechanism is to be mounted.
8. The mechanism of claim 1 , wherein the g-weight comprised at least one petal that electrically contacts the tubular enclosure and the contact pin when the g-weight is in the closed position.
9. The mechanism of claim 8 , wherein the g-weight comprises a plurality of petals that electrically contacts the tubular enclosure and the contact pin when the g-weight is in the closed position.
10. The mechanism of claim 9 , wherein the petals are wedged between the tubular enclosure and the contact pin when the g-weight is in the closed position.
11. The mechanism of claim 10 , wherein the g-weight further comprises a tapered void for receiving the contact pin when the g-weight is in the closed position.
12. The mechanism of claim 1 , wherein the transparent closure is removable without damaging the removable enclosure or the tubular enclosure.
13. The mechanism of claim 12 , wherein the g-weight is removable from the tubular enclosure without damaging the g-weight or the tubular enclosure.
14. The mechanism of claim 1 , further comprising a switch terminal that locates the contact pin relative to the tubular enclosure.
15. The mechanism of claim 14 , further comprising a preformed solder ring that connects the switch terminal to the tubular enclosure.
16. The mechanism of claim 1 , wherein the threshold acceleration is above 25,000 g's.
17. The mechanism of claim 16 , wherein the threshold acceleration is between 25,000 g's and 65,000 g's.
18. The mechanism of claim 1 , wherein the continuous electrical path is for completing an arming circuit in an explosive or energetically assisted projectile.