What is Micro Switch?
is an electrical switch activated by very small physical forces, through the use of a stop mechanism, sometimes referred to as a “hub” mechanism.
The switching occurs inevitably in the specific and repetitive positions of the actuator, which is not necessarily true of other mechanisms. They are very popular due to their low cost and durability, over 1 million cycles, and up to 10 million cycles for heavy-duty models. This durability is a natural result of the design.
The defining feature of the small switch is that a relatively small movement in the actuator node produces a relatively large movement of the electrical contacts, which occurs at high speeds (regardless of the starting speed). Most successful designs also exhibit lag, which means that a slight actuator reversal is not enough to reverse the contacts; There must be a substantial movement in the opposite direction. Both of these help achieve clean and reliable interruptions to the switching circuit.
How the micro switch works :
In a microswitch type, internally there are two conduction springs. A long flat spring is hinged on one end of the adapter (left, pictured) and has electrical contacts on the other. A small curved spring, preloaded (i.e. compressing during assembly) so it tries to extend itself (at the top, just to the right of the middle of the image), which is joined between the flat spring near the contacts and the fulcrum near the midpoint of Spring Flat. The knob actuator presses on the flat spring near the hinge point.
Because flat springs are anchored and strong in tension, curved springs cannot be moved to the right. Curved, or pulled springs, springs are flat upwards, away, from the anchor point. Due to geometry, the up force is proportional to the downward movement as the flat slippery candle moves down. (Actually, the force is proportional to the sine of the angle, which is roughly proportional to the angle for the small angle.)
When the actuator drops it flexes the spring flat while the curved spring keeps the electrical contacts to touch. When the flat spring is flexed enough, it will provide enough force to compress the bent spring and the contacts will begin to move.
As the flat spring slides down, the thrust of the curved spring decreases causing the movement to accelerate even in the absence of the drive’s continued movement until the flat spring interacts with normal contact. Although the flat spring unflexes when it moves down, the convertible is designed so net efficiency is accelerated. This “center” action produces a distinctive flicker sound and a very crisp feel.
In the position activated, the curved spring provides some thrust. If the actuator is released, it will move the flat spring upwards. As the flat spring moves, the force from the curved spring increases. This results in acceleration until the normal contacts are closed. Just like downward, the switch is designed so that the bent brace is strong enough to move the contacts, even when the flat spring has to be bent because the actuator does not move during the transition.
Applications: Common applications of small switches include microwave door locks, balancing and safety devices in elevators, vending machines, and to detect paper jams or other errors in the copier. Small switches are often used in forged switches on gate valves on fire fighting systems and other plumbing systems, where it is necessary to know if the valve has been opened or closed.
Small switches are widely used; Among their applications are home appliances, machinery, industrial controls, vehicles, switchgear masks and many other places for controlling electrical circuits. They are typically rated for carrying only control circuits, although some switches can be used directly to drive small motors, solenoids, lamps or other devices. Special low-force versions can recognize coins in vending machines, or with a propeller attached to the air. Small switches can be operated directly by a mechanism or can be packaged as pressure, flow or temperature transducer, operated by a sensing mechanism such as a Bourdon tube. In later applications, Actuator position repeatability when conversion occurs is essential for lasting accuracy. A cam motor (usually relatively slow speed) and one or more small switches form a timer mechanism. The displacement mechanism can be encased in a metal housing including an action lever, camshaft or roller, making it a limit switch useful for the electric control of machine tools or machines.
Micro Switch and application in life
What is Micro Switch?