Automatic Strap Retractor Tensioner

Abstract

An automatic strap retractor tensioner comprises a winding assembly (winding rod, coupling shaft with first/second coupling gears; the third contact surface of the first gear engages the first contact surface of the winding rod for motion transmission), a tightening assembly (tightening body with slidably mounted first stop plate at inner mid-portion, rotatably coupled to the winding rod and equipped with a protective rubber handle), a braking assembly (brake body with rotatably mounted first brake plate at inner bottom and slidably mounted second brake plate at inner middle), and a take-up assembly (on the brake body’s side, housing a coil spring connected to the winding rod’s second contact surface for strap retraction). Their coordinated action reduces excess strap, enables controllable retraction speed, and enhances safety and usability.

1 . An automatic strap retractor tensioner comprising:  
       a winding assembly including a winding rod, a coupling shaft disposed on the winding rod, a first coupling gear coupled to a first end of the coupling shaft, and a second coupling gear coupled to an opposite end of the coupling shaft, the winding rod having at one end a first contact surface and a second contact surface disposed outward of the first contact surface, and the first coupling gear including a third contact surface at a central location that contacts the first contact surface to transmit motion;  
       a tightening assembly including a tightening body and a first stop plate slidably coupled along an inner circumferential wall of a mid‑portion of the tightening body, the tightening body having a first end rotatably connected to the winding rod and an opposite end provided with a protective rubber handle;  
       a braking assembly including a brake body, a first brake plate rotatably connected along an inner bottom circumferential wall at one end of the brake body, and a second brake plate slidably coupled along an inner middle circumferential wall at one end of the brake body; and  
       a take‑up assembly connected to a side of the brake body and housing a coil spring, the second contact surface of the winding rod being connected to the coil spring within the take‑up assembly. 
     
     
         2 . The automatic strap retractor tensioner of  claim 1 , wherein opposite ends of the coupling shaft respectively include three sector‑shaped protruding interfaces, and surfaces of the second coupling gear and the first coupling gear respectively include three sector‑shaped recesses configured to mate with the sector‑shaped protruding interfaces. 
     
     
         3 . The automatic strap retractor tensioner of  claim 2 , wherein a first protective sleeve is disposed on an outer side of the first coupling gear, and a second protective sleeve is disposed on an outer side of the second coupling gear. 
     
     
         4 . The automatic strap retractor tensioner of  claim 1 , wherein opposite sides of one end of the tightening body respectively include a first engagement plate and a second engagement plate, a spring is provided at a rear end of the first stop plate, and a first rubber sleeve is mounted on the first stop plate such that pressing the first rubber sleeve drives the first stop plate to move. 
     
     
         5 . The automatic strap retractor tensioner of  claim 1 , wherein a retaining ring is disposed below the first brake plate and a retaining ring is disposed above the second brake plate, a second rubber sleeve is mounted at a top end of the first brake plate, and brake fold plates are connected to both sides of a bottom end of the first brake plate. 
     
     
         6 . The automatic strap retractor tensioner of  claim 1 , further comprising a strap disposed on the winding rod. 
     
     
         7 . The automatic strap retractor tensioner of  claim 6 , wherein the second brake plate is configured to limit movement of the strap on the winding rod. 
     
     
         8 . The automatic strap retractor tensioner of  claim 1 , wherein the tightening body is a concave plate‑shaped structure. 
     
     
         9 . The automatic strap retractor tensioner of  claim 3 , wherein the first protective sleeve covers a junction between the first coupling gear and a first end of the coupling shaft, and the second protective sleeve covers a junction between the second coupling gear and an opposite end of the coupling shaft. 
     
     
         10 . The automatic strap retractor tensioner of  claim 5 , wherein the second rubber sleeve is configured to facilitate manual pressing of the first brake plate. 
     
     
         11 . The automatic strap retractor tensioner of  claim 4 , wherein pressing the first rubber sleeve opens the first stop plate and shifts the tightening assembly to an expanded position. 
     
     
         12 . The automatic strap retractor tensioner of  claim 11 , wherein moving the tightening assembly to the expanded position presents a larger effective contact surface on the tightening body against the second brake plate to open the second brake plate. 
     
     
         13 . The automatic strap retractor tensioner of  claim 6 , wherein with the tightening assembly in a tightened position, reciprocating the tightening assembly rotates the first coupling gear and the second coupling gear to shorten an exposed length of the strap. 
     
     
         14 . The automatic strap retractor tensioner of  claim 6 , wherein releasing the first brake plate and the second brake plate allows a coil spring within the take‑up assembly to rewind the strap for retrieval. 
     
     
         15 . The automatic strap retractor tensioner of  claim 5 , wherein a retaining ring below the first brake plate and a retaining ring above the second brake plate are positioned to respectively secure the first brake plate from below and the second brake plate from above.