Self-adjusting pre-tensioning device for roller shade

A self-adjusting pre-tensioning device for a roller shade, the roller shade comprising a fixed brake member, a support roller and a core rod, and the device comprising:

• a brake assembly;
• and
• a spring;
• wherein the brake assembly is arranged at a first end of the core rod;
• and the fixed brake member and the support roller are arranged at a second end of the core rod;
• the brake assembly comprises a rotary outer sleeve, a sleeve seat, a clutch mechanism and a mounting frame;
• a first end of the spring is hooked onto an outer end of the rotary outer sleeve, and a second end of the spring is hooked onto an outer end of the fixed brake member;
• an inner sidewall of the rotary outer sleeve is evenly provided with a plurality of ratchet teeth along a circumferential direction of the rotary outer sleeve;
• the sleeve seat is axially limited and embedded within the rotary outer sleeve, and is non-rotatably and fixedly engaged with the core rod;
• the clutch mechanism is arranged inside the sleeve seat;
• the clutch mechanism is provided with a locking pawl capable of moving along a radial direction of the sleeve seat;
• and the locking pawl is configured to cooperate with the plurality of ratchet teeth to form a one-way locking mechanism;
• the mounting frame is provided with an unlocking tongue;
• and the unlocking tongue is slidably inserted into the sleeve seat, and is configured to abut against the clutch mechanism to drive the locking pawl to radially extend and retract;
• in response to a pre-tensioned state, the mounting frame is disengaged from the clutch mechanism, the locking pawl is configured to extend out of the sleeve seat and engage with the plurality of ratchet teeth;
• and
• in response to a released state, the mounting frame is inserted into the sleeve seat, the locking pawl is configured to retract into the sleeve seat and disengage from the plurality of ratchet teeth.