Patent Publication Number: US-11396093-B2

Title: Puller structure

Description:
This application is being filed as a Continuation-in-Part of U.S. patent application Ser. No. 16/165,080, filed Oct. 19, 2018, currently pending. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to hand tools and more particularly to the structure of a puller. 
     2. Description of Related Art 
     Conventional pullers can be divided into two structural configurations as shown respectively in  FIG. 6  and  FIG. 7 . In either configuration, a plurality of gripping arms are configured to be fastened securely to a workpiece (e.g., a bearing) so that a shaft can be pushed into or pulled out of the workpiece via the spiral action of a threaded rod. Whether a conventional puller can work properly and achieve the intended effect, therefore, depends on whether its gripping arms can be securely fastened to a workpiece. In particular, the larger a workpiece is, the greater the gripping distance formed between the gripping arms must be in order to fasten the gripping arms securely to the workpiece. 
     Referring to the conventional puller in  FIG. 6 , each gripping arm  71  is pivotally connected at the top end to a connecting arm  72  of a fixed length and is also connected to a driving arm  73 . The driving arms  73  can push the gripping arms  71  outward respectively to form the desired gripping distance. The greatest distance to which the gripping arms  71  can be pushed outward with respect to each other is referred to as the span of the gripping arms  71 . When this puller is used on a relatively large workpiece  74  whose size is smaller than the span of the gripping arms  71  but larger than the maximum effective gripping distance between the gripping arms  71  as shown in  FIG. 6 , the gripping arms  71 , which are pivotally connected to the connecting arm  72  at fixed positions and hence do not allow the gripping distance to be further increased, cannot grip the workpiece  74  securely. 
     Referring to the conventional puller in  FIG. 7 , each gripping arm  81  is slidably connected at the top end to a connecting arm  82  of a fixed length, and the gripping distance between the gripping arms  81  is equal to the span of the gripping arms  81 ; that is to say, the distance between the gripping arms  81  dictates the size of a workpiece  83  that can be securely gripped by the gripping arms  81 . This type of pullers, however, generally have a relatively long connecting arm  82  that results in bulkiness and consequently inconvenience in storage. 
     Referring to the conventional puller in  FIG. 8 , a gripping arm  91  is pivotally connected at a fixed position (pivot joint  94 ) of the connecting arm  92  and the driving arms  93 , therefore the gripping arm  91  is not slidable relative to the connecting arm  92  and the driving arms  93 . The connecting arm  92  and the driving arms  93  both are swayable and are extended along the same direction so that the connecting arm  92  and the driving arms  93  cannot remain a permanently extend direction. Eventually, a distance between the two pivot joints  94  cannot be enlarged, hence the force receive points are all distributed on an upper half section of the gripping arm  91 . 
     BRIEF SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide a puller structure that has a greater span and can be opened wider than its prior art counterparts in order to be fixed on relatively large workpieces and have wider application than the conventional pullers. 
     To achieve the above objective, the present invention provides a puller structure that includes a threaded rod, a connecting member, a fixing base, and a driven base. The fixing base is provided with a threaded hole while the driven base is provided with a through hole. The top end of the connecting member is provided with a wing nut. The threaded rod extends downward through and is threadedly connected with the wing nut and the threaded hole of the fixing base and then extends through the through hole of the driven base. A plurality of extension arms extend downward from the connecting member and are arranged at intervals and fixedly connected to the driven base. A plurality of first fixing arms extend outward from the fixing base. A plurality of second fixing arms extend outward from the driven base. The first fixing arms extend through the gaps between the extension arms respectively and correspond in position to the second fixing arms vertically and respectively. In addition, each first fixing arm and the corresponding second fixing arm are connected with a gripping arm. The first fixing arms extend permanently and obliquely upward from the fixing base while the second fixing arms extend permanently in a curved manner from the driven base, therefore one end of the second fixing arm is connected to the driven base, the other end of the second fixing arm extends permanently downward. Each first fixing arm has a shorter length than the corresponding second fixing arm. Each first fixing arm is provided with a first groove that extends in the same direction as the first fixing arm, and each second fixing arm is provided with a second groove that extends in the same direction as the second fixing arm. Each gripping arm is slidably provided in the corresponding first groove and the corresponding second groove via a first protruding block and a second protruding block respectively. 
     In one embodiment, the first groove of each first fixing arm is upwardly concavely provided in the bottom side of the first fixing arm, and each first fixing arm has two lateral sides each formed with a first slide slot. Two first protruding blocks are provided respectively on two lateral portions of each gripping arm that face the first slide slots of the corresponding first fixing arm, and extend through the first slide slots of the corresponding first fixing arm respectively. The second groove of each second fixing arm penetrates the second fixing arm vertically, and each second fixing arm has two lateral sides each formed with a second slide slot. Two second protruding blocks are provided respectively on two lateral portions of each gripping arm that face the second slide slots of the corresponding second fixing arm, and extend through the second slide slots of the corresponding second fixing arm respectively. 
     Preferably, a plurality of first positioning recesses are provided along the bottom edge of each first slide slot in a wavy configuration, and a plurality of second positioning recesses are provided along the bottom edge of each second slide slot in a wavy configuration. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a perspective view of the puller structure according to the first embodiment of the present invention; 
         FIG. 2  is an exploded perspective view of the puller structure in  FIG. 1 ; 
         FIG. 3  and  FIG. 4  show certain states of use of the puller structure in  FIG. 1 ; 
         FIG. 5  is a perspective view of the puller structure according to the second embodiment of the present invention; 
         FIG. 6  schematically shows a conventional puller structure; 
         FIG. 7  schematically shows another conventional puller structure; and 
         FIG. 8  schematically shows another conventional puller structure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1  and  FIG. 2 , the puller structure according to the first embodiment of the present invention includes a threaded rod  1 , a connecting member  2 , a fixing base  3 , and a driven base  4 . The connecting member  2  is provided with a wing nut  21  at the top end. The fixing base  3  lies under the connecting member  2 , and the driven base  4  lies under the fixing base  3 . Three extension arms  22  extend downward from the connecting member  2  and are arranged at intervals and fixedly connected to the driven base  4 . The fixing base  3  is provided with a threaded hole  31 . The driven base  4  is provided with a through hole  41 . The threaded rod  1  is threadedly connected to the wing nut  21 , then extends downward to be threadedly connected to the fixing base  3  via the threaded hole  31 , and extends further downward through the through hole  41  of the driven base  4 . 
     The fixing base  3  is provided with three first fixing arms  32  that extend outward. The first fixing arms  32  extend through the gaps between the extension arms  22  respectively. More specifically, each first fixing arm  32  extends permanently and obliquely upward from the fixing base  3 . The driven base  4  is provided with three second fixing arms  42  that extend outward. More specifically, each second fixing arm  42  extends permanently from the driven base  4  in a curved manner, therefore one end of the second fixing arm  42  is connected to the driven base  4 , the other end of the second fixing arm  42  extends permanently downward. The positions of the first fixing arms  32  correspond vertically and respectively to those of the second fixing arms  42 . The length of each first fixing arm  32  is shorter than that of the corresponding second fixing arm  42 . 
     Each first fixing arm  32  is provided with a first groove  33  that extends in the same direction as the first fixing arm. In this embodiment, each first groove  33  is upwardly concavely provided in the bottom side of the corresponding first fixing arm  32 , and the two lateral sides of each first fixing arm  32  are each formed with a first slide slot  34 . Each second fixing arm  42 , on the other hand, is provided with a second groove  43  that extends in the same direction as the second fixing arm. In this embodiment, each second groove  43  penetrates the corresponding second fixing arm  42  vertically, and the two lateral sides of each second fixing arm  42  are each formed with a second slide slot  44 . 
     Each pair of first and second fixing arms  32 ,  42  that correspond in position to each other are connected with a gripping arm  5 . The bottom end of each gripping arm  5  is provided with a hook  51  to be hooked to a workpiece. Each gripping arm  5  extends through the second groove  43  of the corresponding second fixing arm  42  into the first groove  33  of the corresponding first fixing arm  32 . The two lateral portions of each gripping arm  5  that face the first slide slots  34  of the corresponding first fixing arm  32  respectively are each provided with a first protruding block  52 , and the two lateral portions of each gripping arm  5  that face the second slide slots  44  of the corresponding second fixing arm  42  respectively are each provided with a second protruding block  53 . The first protruding blocks  52  and the second protruding blocks  53  of each gripping arm  5  are provided in the corresponding first slide slots  34  and the corresponding second slide slots  44  respectively in a slidable manner so that the positions at which each gripping arm  5  is connected respectively to the corresponding first fixing arm  32  and the corresponding second fixing arm  42  can be changed. 
     The puller structure described above is used in the following manner. To begin with, referring to  FIG. 3 , the wing nut  21  is operated to adapt the puller structure to the size of the workpiece  6 A to be worked on. More specifically, the wing nut  21  is operated to move the connecting member  2 , in order for the connecting member  2  to move the driven base  4  and thereby adjust the second fixing arms  42  to appropriate positions. Then, with the first protruding blocks  52  and the second protruding blocks  53  of each gripping arm  5  sliding freely in the corresponding first slide slots  34  and the corresponding second slide slots  44  respectively, the gripping arms  5  are opened as wide as the workpiece  6 A and eventually fastened securely to the workpiece  6 A so that the threaded rod  1  can be rotated to pull out the shaft in the workpiece  6 A. 
     According to the above, the span of, and the gripping distance between, the gripping arms  5  can be adjusted by varying the positions at which each gripping arm  5  is connected respectively to the corresponding first fixing arm  32  and the corresponding second fixing arm  42 , and this allows the puller structure to adapt to workpieces of different sizes. When the puller structure is used on a workpiece  6 B (see  FIG. 4 ) wider than the workpiece  6 A in  FIG. 3 , the first protruding blocks  52  at the top end of each gripping arm  5  can be slid inward with respect to the corresponding first fixing arm  32  (i.e., the position at which each gripping arm  5  is connected to the corresponding first fixing arm  32  can be moved inward with respect to the corresponding first fixing arm  32 ), and the second protruding blocks  53  on the middle section of each gripping arm  5  can be slid outward with respect to the corresponding second fixing arm  42  (i.e., the position at which each gripping arm  5  is connected to the corresponding second fixing arm  42  can be moved outward with respect to the corresponding second fixing arm  42 ), in order to further increase the span of, and the gripping distance between, the gripping arms  5  and thereby adapt the puller structure to the workpiece  6 B. 
     Another advantage of the present invention is that, while the disclosed puller structure is applicable to relatively large workpieces, the space occupied by the puller structure is smaller than its prior art counterparts because the first fixing arms  32  are shorter than the second fixing arms  42 . 
       FIG. 5  shows the second embodiment of the present invention. This embodiment is structurally based on the first embodiment and demonstrates a structural variation of the first slide slots  34  and of the second slide slots  44 . In this embodiment, the bottom edge of each first slide slot  34  is provided with a plurality of first positioning recesses  341  that form a wavy shape, and the bottom edge of each second slide slot  44  is provided with a plurality of second positioning recesses  441  that also form a wavy shape. When the puller structure of this embodiment is used to pull out a shaft, the first protruding blocks  52  of each gripping arm  5  can be respectively engaged in particular ones of the first positioning recesses  341  of the corresponding first slide slots  34 , and the second protruding blocks  53  of each gripping arm Scan be respectively engaged in particular ones of the second positioning recesses  441  of the corresponding second slide slots  44 , thereby securing the gripping arms  5  in position. 
     Besides, referring to  FIG. 3  and  FIG. 4 , according to the first fixing arm  32  extends permanently and obliquely upward from the fixing base  3 , and one end of the second fixing arm  42  extends permanently downward, therefore a distance between the first protruding blocks  52  and the second protruding blocks  53  can be enlarged than the conventional structure. Eventually, the force receive points on the gripping arms  5  are evenly distributed, and a gripping width of the two gripping arms  5  can be expanded.