Motor applications for smart locks on lightweight doors and apartment doors
In the smart home sector, there is a wide variety of smart locks. Today, we focus on why the 370 brushed motor combined with a worm gear gearbox serves as the core component for locks on lightweight security doors, interior doors, and apartment doors.
Working principle of smart locks:
User authentication via 3D facial recognition, fingerprint scanning, or passcode entry initiates unlocking.
The MCU processes the command and sends a PWM signal via the BDR6133 driver.
The PWM signal activates the brushed motor, causing it to rotate.
The worm gear gearbox regulates the motor speed and converts rotational motion into high torque.
This torque drives the latch extension/retraction mechanism, generating the thrust needed to unlock the smart lock.
Throughout the unlocking process, the system must meet the following specifications: response time ≤0.3 seconds, operating noise <35 dB, and output torque ≥45 mN·m (satisfying national standards for security latch thrust) to suit lightweight security doors. Additionally, standby current must remain <5 μA, with an operating current of 0.6 A.
Lightweight security doors and apartment doors typically feature a thickness of 40–60 mm and weigh around 50 kg. The 370 brushed motor paired with a worm gear gearbox measures just 24.4 mm, making it ideal for internal integration. With a 1:50 gear ratio, the system delivers an output torque of 45 mN·m; this ratio can be adjusted to further increase torque if needed. The complete geared motor assembly achieves a response time of ≤0.3 seconds.
In real-world applications, common examples include:
Xiaomi Push-Pull Smart Lock: Utilizes a 24mm motor to automatically retract the angled latch, delivering a "push-to-open" experience with a 0.3-second response time. It is compatible with 90% of aluminum alloy entry doors.
Dessmann Q3M Interior Interconnected Lock: Features dual 24mm motors that independently control the main latch and top/bottom bolts. Using an H-bridge circuit for dual-channel independent braking, it is ideal for gym lockers and office partition doors.
Guanlin AH-A8 Apartment Access Control: Integrates motor联动 (motor linkage) with magnetic door sensors. Upon card swipe, the latch automatically retracts, eliminating the impact noise associated with traditional electromagnetic locks (tested noise levels <28 dB).
Hikvision Facial Recognition Access Control: Incorporates an optical encoder within the motor to precisely control latch extension and retraction travel (with an error margin of ±0.1mm), effectively preventing finger-pinching accidents.