Sensing in Elevator
There are four primary types of elevator's movement mechanisms: traction, hydraulic, vacuum and climbing. Sensors used in all types of elevators include infrared, level, current, load and hall-effect sensors, limit switches and encoders. Encoders are used to detect motor’s rotation speed so as to control the motion and position of the elevator car. Meanwhile, current sensors detect motor’s working current based on the power of motor and could be adjusted to a proper level. Leveling sensors transmit the floor- number to control center, in order to activate the brake mechanism to ensure that the elevator stops at the desired level.
Sensors, achieving this, are actually optoelectronic sensors or smart position sensors mounted in elevator shaft or at top of car. Also, some elevators use hall-effect sensors to sense car position. To prevent elevators from running off the rails, limit switches are required to set a highest and a lowest position for car. Infrared sensors are located in car to detect obstacles at doors with purpose to prevent passengers from being caught between doors. In addition, there is a load sensor mounted at the bottom of car to monitor load and initiate the overloading alarm as required.
The rapid development of sensor technology will bring more products of different unique capabilities to modern elevators, and is bound to make them more intelligent and environment-friendly in the future.