A spring exerciser

Abstract

A spring exerciser, including a case, a pull strap, and a rewinding mechanism having a supporting shaft and a rewinding hub rotatably sleeving the supporting shaft; the rewinding hub includes an inner cavity and a winding groove; a torsion spring is installed in the inner cavity; two ends of the torsion spring are hooked to the supporting shaft and to the rewinding hub respectively; the pull strap includes a middle portion positioned in the inner cavity, a first end portion, and a second end portion; the first end portion passes through the inner cavity and winds around the winding groove; the second end portion also passes through the inner cavity and winds around the winding groove; the first end portion and the second end portion wind in the winding groove to form layers of winding coils defined alternately by the first end portion and the second end portion.

What is claimed is: 
     
         1 . A spring exerciser, comprising a case, a pull strap, and a rewinding mechanism; wherein:
 the rewinding mechanism comprises a supporting shaft fixed inside the case, and also comprises a rewinding hub arranged inside the case and rotatably sleeving the supporting shaft; the rewinding hub comprises an inner cavity and a winding groove annularly provided outside an outer wall of the inner cavity; a torsion spring is installed in the inner cavity; one end of the torsion spring is fixed to the supporting shaft, and another end of the torsion spring is fixed to the rewinding hub;   the pull strap comprises a middle portion, as well as a first end portion and a second end portion respectively provided at two ends of the middle portion; the middle portion is positioned in the inner cavity; the first end portion passes through a first opening at one side of the outer wall of the inner cavity and is wound in the winding groove; the second end portion passes through a second opening at another side of the outer wall of the inner cavity and is also wound in the winding groove; the first end portion and the second end portion are both wound in the winding groove to form layers of winding coils defined alternately by the first end portion and the second end portion;   an end of the first end portion distal from the middle portion passes through one side of the case and is connected with a first handle; an end of the second end portion distal from the middle portion passes through another side of the case and is connected with a second handle or a fixing component.   
     
     
         2 . The spring exerciser of  claim 1 , wherein the first end portion passes through the first opening and winds around an upper peripheral wall of the rewinding hub, and then winds around an outer side of the second end portion passing through the second opening; the second end portion passes through the second opening and winds around a lower peripheral wall of the rewinding hub, and then winds around an outer side of the first end portion passing through the first opening; therefore, the first end portion and the second end portion are wound in the wind groove to form layers of winding coils defined alternately by the first end portion and the second end portion. 
     
     
         3 . The spring exerciser of  claim 2 , wherein the inner cavity comprises a first cavity surrounding the supporting shaft and defined within an inner wall of the inner cavity, and a second cavity outside the first cavity; the second cavity is defined between the inner wall of the inner cavity and the outer wall of the inner cavity, and is separated from the first cavity by the inner wall of the inner cavity; the torsion spring is installed in the first cavity; the middle portion is positioned in the second cavity; the first opening allowing the first end portion to pass through is positioned at one side of a side wall of the second cavity, and the second opening allowing the second end portion to pass through is positioned at another side of the side wall of the second cavity. 
     
     
         4 . The spring exerciser of  claim 3 , wherein the rewinding hub comprises a hub body and a side cover; the first cavity and the second cavity are provided on the hub body and have openings facing towards the side cover; the side cover covers the openings of the first cavity and the second cavity; the hub body comprises an annular stopping edge which is provided on an outer periphery of a side of the hub body distal from the side cover; the winding groove is defined between the annular stopping edge and an outer peripheral edge of the side cover. 
     
     
         5 . The spring exerciser of  claim 4 , wherein a set of limiting-and-butting blocks is provided on an inner surface of the side cover corresponding to the second cavity; the set of limiting-and-butting blocks is inserted into the second cavity and presses against the middle portion of the pull strap, such that the middle portion of the pull strap is limited in the second cavity and is not capable of being displaced circumferentially in the second cavity. 
     
     
         6 . The spring exerciser of  claim 4 , wherein a bottom wall of the first cavity is provided with a first through hole allowing the supporting shaft to pass through; the side cover is provided with a second through hole allowing the supporting shaft to pass through; one bearing is provided on the supporting shaft adjacent the first through hole, and another bearing is provided on the supporting shaft adjacent the second through hole; two ends of the supporting shaft pass through the first through hole and the second through hole respectively, and the two ends of the supporting shaft are each connected with a hex nut; the case is jointly formed by a first half shell and a second half shell joined together; inner walls of the first half shell and the second half shell are provided with a first inner hexagonal limiting hole and a second inner hexagonal limiting hole respectively; each of the inner hexagonal limiting hole and the inner hexagonal limiting hole allows insertion and fixation of a corresponding hex nut. 
     
     
         7 . The spring exerciser of  claim 1 , wherein said one side of the case is provided with a first hole allowing the end of the first end portion distal from the middle portion to pass through, and said another side of the case is provided with a second hole allowing the end of the second end portion distal from the middle portion to pass through; the first hole, the second hole, the first opening, and the second opening are all located on a central plane that aligns with a central axis of the supporting shaft. 
     
     
         8 . The spring exerciser of  claim 1 , wherein the first handle is detachably connected to the end of the first end portion passing through the case, and the second handle or the fixing component is detachably connected to the end of the second end portion passing through case. 
     
     
         9 . The spring exerciser of  claim 8 , wherein the end of the first end portion passing through the case is provided with a first thread connecting portion, and the end of the second end portion passing through the case is provided with a second thread connecting portion; the first handle and the second handle are of the same structure, each includes an annular grip band, a grip sleeve wrapping around one end of the annular grip band, and a first thread connecting head; the first thread connecting head is provided at another end of the annular grip band and is detachably connected to the first thread connecting portion or the second thread connecting portion; the fixing component comprises a fixing band, a resting component arranged at one end of the fixing band, and a second thread connecting head arranged at another end of the fixing band; the second thread connecting head is detachably connected to the second thread connecting portion; an outer surface of the resting component is covered with a protective layer. 
     
     
         10 . The spring exerciser of  claim 1 , wherein the end of the first end portion and the end of the second end portion, both distal from the middle portion, pass through a left side and a right side of the case respectively; an upper side of the case is provided with a third thread connecting portion; the spring exerciser further comprises a third handle, and the third handle comprises a first grip and a second grip separated from each other, and also comprises a third thread connecting head detachably connected with the third thread connecting portion.