Patent Publication Number: US-11655672-B2

Title: Device for restricting torsion spring of scrolling device of window curtain from reversely expanding

Description:
BACKGROUND OF THE INVENTION 
     1. Fields of the Invention 
     The present invention relates to a scrolling device of a window curtain, and more particularly, to an adjustment device cooperating with the scrolling device to restrict the torsion spring of the scrolling device from reversely expanding. 
     2. Descriptions of Related Art 
     The conventional scrolling device in a rope-less window curtain includes a torsion spring which provides a force to be balanced with the curtain weight so as to easily operate the curtain. 
     The torsion spring is connected to a rotary axle, and the torque from the torsion spring makes the rotary axle be rotated. A weight is attached to the bottom rail of the window curtain, and when the weight and the force from the torsion spring reaches a balance status, the curtain can be operated without need of control ropes. 
     The torsion spring is mounted to a fixed shaft, and a sleeve is connected to one end of the fixed shaft. The combination of the torsion spring, the fixed shaft and the sleeve is received in a tube. When the curtain is pulled downward, the tube is rotated with the curtain to further twist the torsion spring which generate a torque to balance the weight of the bottom rail. When pushing the curtain upward to break the balance mentioned above, only the recovery force of the torsion spring wraps the curtain to the tube, until the user releases the curtain, the weight of the bottom rail and the torque reach a balance again to stop the curtain. 
     It is noted that the assembling of the torsion spring to the fixed shaft is difficult. This is because the torsion spring has a free end, so that the torsion spring has to be compressed first, and then presses a plate to the free end of the torsion spring. If the assembling steps are not completed within a short period of time, the torsion spring bounces back. The assembling steps have to be repeated again. 
     The present invention intends to provide an adjustment device that is connected to the scrolling device so as to restrict the torsion spring of the scrolling device from reversely expanding. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a window curtain and comprises a top rail, a bottom rail, a tube and a curtain. The tube is located in the top rail. Two plates are respectively connected to two ends of the top rail. The curtain is wrapped around the tube and connected to the bottom rail. A scrolling device is located in the tube and includes a torsion spring, a fixed shaft and a sleeve. The torsion spring is mounted to the sleeve, and the sleeve is connected to the fixed shaft and is secured to the inside of the tube. An adjustment unit is connected to the fixed shaft. The torsion spring is located between the sleeve and the adjustment unit. The adjustment unit includes a housing, a tubular part and a resilient member. The resilient member is mounted to the tubular part which is partially located in the housing. The resilient member is located within the housing and is biased between the housing and the tubular part so that the first end of the tubular part movably protrudes beyond the housing. The first end of the torsion spring is fixed to the tubular part so that the torsion spring is compressed or released by rotating the adjustment unit. One of the two plates includes a tongue that is inserted into the second end of the tubular part to maintain the first end of the tubular part to protrude beyond the housing. 
     Preferably, a bearing is located between the tube and each of the plates. 
     Preferably, the tubular part includes ratchets protruding from the second end thereof. The housing includes a pawl protruding from the inside thereof. The pawl is engaged with one of the ratchets to prevent the tubular part from rotating reversely. 
     Preferably, the tubular part includes a recess defined in the second end of the tubular part. The recess is a rectangular recess which is adapted to receive a tool inserted therein to rotate the tubular part to adjust the torsion spring when the tongue is removed. 
     The advantages of the present invention are that the adjustment unit maintain the torsion spring from reversely expanding so that the whole combination of the scrolling device and the adjustment unit can easily be installed in the tube. 
     The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view to show the window curtain using the adjustment unit of the present invention; 
         FIG.  2    is an exploded view of the window curtain of the present invention; 
         FIG.  3    shows the scrolling device and the adjustment unit of the present invention; 
         FIG.  4    is a cross sectional view to show the combination of the scrolling device and the adjustment unit are located in the tube, and a plate is to be connected to the second end of the tubular part; 
         FIG.  5    is a cross sectional view to show that the tubular part is moved toward the sleeve to compress the torsion spring, and 
         FIG.  6    shows that the curtain of the window curtain is pulled, and the operation of the scrolling device. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIGS.  1  to  6   , the window curtain  100  of the present invention comprises a top rail  10 , a bottom rail  20 , a tube  30  and a curtain  40 . The tube  30  is located in the top rail  10 . Two plates  11  are respectively connected to two ends of the top rail  10 . The curtain  40  includes the first end thereof wrapped to the tube  30 , and the second end of the curtain  40  is connected to the bottom rail  20 . A scrolling device  50  is located in the tube  30  so as to lift or lower the curtain  40 . The scrolling device  50  includes a torsion spring  51 , a fixed shaft  52  and a sleeve  53 . The torsion spring  51  is mounted to the sleeve  53 . The sleeve  53  is connected to the fixed shaft  52  and is secured to the inside of the tube  30 . The curtain  40  is stopped at a desired position by the force of the torsion spring  51 . 
     An adjustment unit  60  is connected to the fixed shaft  52 , and the torsion spring  51  is located between the sleeve  53  and the adjustment unit  60 . The adjustment unit  60  includes a housing  61 , a tubular part  62  and a resilient member  63 . The resilient member  63  is mounted to the tubular part  62  which is partially located in the housing  61 . The resilient member  63  is located within the housing  61  and biased between the housing  61  and the tubular part  62  so that the first end of the tubular part  62  movably protrudes beyond the housing  61  by the force from the resilient member  63 . The first end of the torsion spring  51  is fixed to the tubular part  62 . The torsion spring  51  is compressed or released by rotating the adjustment unit  60 . One of the two plates  11  includes a tongue  12  that is inserted into a recess  622  in the second end of the tubular part  62  to maintain the first end of the tubular part  62  to protrude beyond the housing  61 . The torsion spring  51  is re-stored an energy. The whole adjustment unit  60  is installed in the tube  30 . 
     As shown in  FIG.  2   , a bearing  70  is located between the tube  30  and each of the plates  11 , so that the tube  30  is rotated smoothly. 
     Specifically, as shown in  FIGS.  2  and  3   , the tubular part  62  includes ratchets  621  protruding from the second end thereof. The housing  61  includes a pawl  611  protruding from the inside thereof. The pawl  611  is engaged with one of the ratchets  621  to prevent the tubular part  62  from rotating reversely. Therefore, the torsion spring  51  is maintained with the pre-stored energy. 
     As shown in  FIG.  3   , the tubular part  62  includes the recess  622  defined in the second end of the tubular part  62 . In this embodiment, the recess  622  is a rectangular recess  622  so that a tool can be inserted into the recess  622  and rotates the tubular part  62  to adjust the torsion spring  51  when the tongue  12  is removed. 
     As shown in  FIGS.  4  to  6   , the adjustment unit  60  is located at one end of the torsion spring  51  and is able to adjust the torsion spring  51 . One of the two plates  11  is connected to the second end of the tubular part  62  so as to keep the torsion spring  51  in a compressed status, and the combination of the scrolling device  60  and the adjustment unit  60  is received in the tube  30  easily. The curtain  40  can be pulled downward or pushed upward, and is stopped at a desired position by the balance between the force of the torsion spring  51  and the weight of the bottom rail  20 . 
     While we have shown and described the embodiment in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.