Overload protection design for range hood electric linear actuators must revolve around the safe operation of the motor, employing multiple protection mechanisms to prevent motor burnout due to abnormal loads. Its core design logic must encompass current monitoring, thermal management, mechanical limits, and intelligent control, forming a complete protection chain from real-time detection to proactive intervention.
Current monitoring is the foundation of overload protection. The actuator must be equipped with a high-precision current sensor to collect the motor's operating current in real time and compare it with the rated value. When the current exceeds the safety threshold, the control circuit must immediately trigger the protection action. For example, using a Hall effect sensor can achieve non-contact current detection, avoiding interference from traditional resistor sampling. Simultaneously, a dynamic threshold adjustment algorithm must be designed to automatically correct the overload judgment criteria based on different operating modes of the range hood (e.g., strong exhaust, weak exhaust) to prevent false triggering affecting normal use.
Thermal management design must complement current monitoring. When the motor is overloaded, not only does the current increase, but the temperature rise also accelerates significantly. Therefore, the actuator must embed an NTC thermistor inside the motor windings to achieve dual protection through temperature feedback. When current monitoring fails to trigger but temperature continues to rise, the thermistor signal can directly cut off the drive circuit, preventing insulation damage to the motor due to localized overheating. Furthermore, the motor housing needs to be designed with heat sink fins, combined with thermal grease to improve heat conduction efficiency and reduce the impact of high temperatures on electronic components.
Mechanical limit devices are crucial for preventing physical overload of the actuator. Range hood electric linear actuators typically employ a lead screw drive structure, requiring mechanical stops and limit switches at both ends of the stroke. When the actuator reaches its limit position, the stop triggers the limit switch, and the control circuit immediately stops the motor power supply and reverses to release pressure. Some high-end designs also employ an elastic buffer structure, using springs to absorb the impact force at the end, avoiding mechanical damage caused by hard collisions. This design protects the motor and extends the service life of transmission components.
Intelligent control algorithms can improve the response accuracy of overload protection. The actuator needs to be equipped with a microcontroller, using a PID algorithm to adjust the motor output torque in real time. When a sudden increase in load is detected, the algorithm can automatically reduce the speed and increase the current output, maintaining continuous operation while avoiding stalling. For example, when the exhaust duct of a range hood is clogged, intelligent control can cause the motor to operate in a low-speed, high-torque mode to attempt to clear the blockage instead of shutting down directly, improving the user experience.
The design of the power management module directly affects the reliability of the protection system. The actuator needs a wide voltage input design to adapt to power grid fluctuations in different regions. When the voltage is too low, causing insufficient motor output, the power management module can actively cut off the power supply to prevent the motor from overheating due to prolonged inefficient operation. Simultaneously, lightning strike and electrostatic discharge protection circuits must be designed to prevent damage to electronic components from transient high voltage.
Fault diagnosis and self-recovery functions can improve the actuator's intelligence level. The control circuit needs to record the type of overload event (such as current overload, overtemperature, mechanical jamming) and provide fault codes via LED indicators or communication interfaces. Some designs also have an automatic restart function, restarting the motor a few seconds after the overload is cleared, avoiding the impact of frequent start-stop cycles on the power grid.
Material selection and manufacturing processes are fundamental guarantees for overload protection. The motor windings must use high-temperature resistant enameled wire with an insulation class of not less than F (155℃) to withstand short-term overload temperature rise. The lead screw must be made of high-strength alloy steel, and its surface must be hardened to improve wear resistance. Electronic components must be RoHS certified to ensure long-term stability. These detailed design features can fundamentally reduce the risk of motor burnout and extend the overall lifespan of the actuator.
