Introduction to microswitches, working reasons and loss measures

A microswitch is a type of switch that has a small contact spacing and a quick action mechanism, and uses a specified stroke and force to perform the switch action. It is covered by a casing and has a driving rod on the outside. Because the contact spacing between its switches is relatively small, it is called a microswitch, also known as a sensitive switch. The electrical text symbol is SM.

operational principle

External mechanical force acts on the action through transmission components (such as pins, buttons, levers, rollers, etc.)

Microswitch

On the spring, when the action spring moves to the critical point, an instantaneous action is generated, causing the moving contact at the end of the action spring to quickly connect or disconnect from the fixed contact.

When the force on the transmission element is removed, the action spring generates a reverse action force. When the reverse stroke of the transmission element reaches the critical point of the spring's action, the reverse action is instantly completed. The contact spacing of micro switches is small, the action stroke is short, the pressing force is small, and the on/off is fast. The operating speed of its moving contacts is independent of the operating speed of the transmission components.

There are various types of micro switches, with hundreds or even thousands of internal structures. They can be classified into ordinary, small, and ultra small types based on body integration; According to protective performance, there are waterproof, dustproof, and explosion-proof types; According to the breaking form, there are single connected, double connected, and multi connected types. There is also a type of strong disconnect microswitch (when the spring of the switch is not working, external force can also cause the switch to disconnect); According to the breaking capacity, there are ordinary type, DC type, micro current type, and high current type. According to the usage environment, there are ordinary type, high-temperature resistant type (250 ℃), and ultra-high temperature resistant ceramic type (400 ℃)

Micro switches are generally based on the basic form of non auxiliary pressing accessories, and derive small and large operating programs. According to the needs, different auxiliary pressing accessories can be added. According to the different pressing accessory switches added, they can be divided into various forms such as button type, spring roller type, lever roller type, short arm type, long arm type, etc.

Micro switches are widely used for automatic control and safety protection in equipment that requires frequent circuit switching. They are widely used in electronic equipment, instruments and meters, mines, power systems, household appliances, electrical equipment, as well as military fields such as aerospace, aviation, ships, missiles, tanks, etc. They have been widely used in these fields. Although small, switches play an irreplaceable role.

At present, the mechanical life of micro switches on the domestic market varies from 3W to 1000W times according to different usage requirements, generally including 10W, 20W, 50W, 100W, 300W, 500W, and 800W times. In China, beryllium bronze, tin bronze, and stainless steel wire are generally used as spring plates, while ALPS abroad can reach up to 1000W times. Their spring plates are made of rare metal titanium. The highest WK-01B produced by domestic Tengfei Electronics can also reach 1000W times.

How to control the loss of microswitches

The loss of micro switches includes two types: wear and fatigue, with wear referring to contact surface wear or material damage; Fatigue means that metals and other related materials produce fatigue cracks or reduce fatigue life. The biggest technical feature of microswitches in design is to prevent losses and extend their lifespan.