Snap switch
A snap-action switch or snap switch is an electric switch , the force -path-characteristic of a pronounced hysteresis shows. The feel is similar to that of the children's toy, the cracking frog .
Force-displacement curve
At the beginning of the actuation the necessary force increases more or less strongly. When the switching point is reached, the mechanical system inside the switch suddenly snaps into the other switching position and the actuating force drops accordingly. In the subsequent blow-out or by pressure or overrun the operating force usually increases again as the typical snap-action switch includes a return spring, the switch brings back to the starting position upon release of the load. When resetting, there is an equally abrupt snap-over, with the switch-back point on the path coordinate before the "go" switch point (switch back takes place after the "go" switch point has been passed)!
use
Due to the hysteretic characteristics, the snap switch is well suited for use in two-point control loops (such as temperature switches): After each changeover, the new switch position is relatively stable, the actuating force must first undergo a significant change in order for the mechanics to work other switching position can snap.
A sufficient minimum contact force can be guaranteed in every position of the actuator.
Designs
The best known and most widespread design is the snapping microswitch , which is mass-produced and used as a standard element in many designs. For example in the microwave oven to recognize the state of the door (open / closed), or in digital computer joysticks such as the Competition Pro .
See also
- Temperature switch - example of a snap switch in which the return spring causes it to snap over at the same time
- Marquardt Group - first manufacturer of snap switches in Germany
- Competition Pro - Popular joystick with snap microswitches from the C-64 era