How is the motor overload protection mechanism implemented in electric folding windows?
Release Time : 2025-11-17
The motor overload protection mechanism of electric folding windows is a core safety design that ensures automatic power cut-off or current limitation when the load abnormally increases during operation, preventing motor damage due to overheating or excessive current. Its implementation typically combines mechanical structures, electrical components, and intelligent control technology to form a multi-layered protection system to meet safety requirements in different scenarios.
The thermal relay is one of the fundamental components of motor overload protection in electric folding windows. Its working principle is based on the thermal effect of current: when the motor is overloaded, the current flowing through the thermal relay exceeds the rated value. The internal bimetallic strip bends due to the difference in thermal expansion coefficients, pushing the contacts to actuate and cut off the control circuit. This protection method is low-cost, simple in structure, and suitable for most small and medium power motors. For example, in the daily opening and closing of electric folding windows, if the motor load suddenly increases due to window jamming or a sudden increase in mechanical resistance, the thermal relay will respond quickly, preventing the motor from burning out due to prolonged overload.
Electronic overload protectors achieve more precise control through microprocessors and current sensors. A current sensor monitors the motor's operating current in real time. When the current exceeds a set threshold, the microprocessor immediately analyzes the load status to determine if it's an overload or short circuit. If an overload is confirmed, the protector quickly cuts off the power and feeds back the fault information via a digital interface. This protection method offers fast response, high accuracy, and can integrate multiple protection functions such as phase loss, locked rotor, and three-phase imbalance. For electric folding windows, electronic protectors can effectively handle complex faults such as window deformation and foreign objects in the tracks, improving the reliability of equipment operation.
Temperature protection mechanisms are another important supplement to overload protection. When a motor operates under overload, the winding temperature will continuously rise. If not intervened in time, this may lead to aging or even combustion of the insulation material. Temperature protection devices typically use thermistors or temperature sensors to directly monitor the internal temperature of the motor. When the temperature exceeds the safe limit, the protection device will trigger a frequency reduction mode, reducing the motor speed to decrease heat generation, or directly cutting off the power. For example, in high-temperature environments, if the motor of an electric folding window overheats due to continuous operation, the temperature protection mechanism can proactively intervene to prevent equipment damage.
Dual monitoring of current and temperature is a common design feature in the overload protection of modern electric folding windows motors. Some high-end systems use current and temperature sensors working together to form redundant protection. When the current exceeds the limit or the temperature is abnormal, the system will first alleviate the overload through methods such as frequency reduction and current limiting; if the fault persists, the power supply will be completely cut off. For example, a certain brand of electric folding windows will cut off the power supply within 0.3 seconds when it detects that the current exceeds 120% of the rated value; at the same time, if the coil temperature reaches 105℃, it will trigger the frequency reduction mode to ensure that the motor operates within a safe range.
The linkage design of mechanical limit and overload protection further enhances the safety of the system. Electric folding windows motors are usually equipped with position sensors to monitor the opening and closing angle of the window in real time. If the window jams due to a mechanical failure, the position sensor will detect that the deviation between the actual position and the target value exceeds the safe range, immediately stop the machine, and report a fault code. This design not only prevents the motor from overloading due to stalling but also avoids damage to the window due to excessive compression. For example, when the window is fully opened or closed, the limit switch triggers the motor to stop, preventing the mechanical structure from deforming due to excessive force.
The introduction of an intelligent control system makes overload protection more intelligent. By integrating AI algorithms, the system can predict load change trends and adjust motor operating parameters in advance. For example, when the window is nearly fully closed, the system will proactively reduce the motor speed to reduce impact force and avoid overload caused by increased instantaneous resistance. Furthermore, the intelligent system can record overload events and generate maintenance logs, providing data support for subsequent troubleshooting.
The motor overload protection mechanism of electric folding windows constructs a comprehensive safety protection system through multiple technologies, including thermal relays, electronic protectors, temperature monitoring, dual redundancy design, mechanical limit linkage, and intelligent control. These mechanisms not only ensure reliable motor operation under abnormal loads but also extend equipment lifespan, reduce maintenance costs, and provide a solid guarantee for the intelligent and safe application of electric folding windows.