Patent Publication Number: US-11376720-B2

Title: High strength wrench

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to a wrench, in particular, to a wrench having a relatively higher structural strength. 
     2. Description of Related Art 
       FIG. 1  shows a conventional ratchet wrench  10  having a head portion  12 , a shaft  14  and a handle  16 . The head portion includes a ratchet mechanism arranged thereon. During the use, the head portion is used to attach onto a nut, bolt or socket, and the operator can hold the handle and rotate the wrench  10  in order to rotate the nut, bolt or socket. 
     The lengths of the shaft  14  and the handle  16  of the conventional wrench  10  are about the same, and the moment arm formed by the shaft  14  and the handle  16  is not long. Consequently, the torque generated from the operating of the wrench is not great, and only a small torque can be provided. As a result, such wrench  10  is applicable to the rotation of fastening elements (nuts or bolts) of small sizes only, and it is not suitable to the rotation of fastening elements of large sizes. Furthermore, the shaft  14  of the conventional wrench has no strength reinforcement design such that the structural strength of the wrench is poor, and it cannot bear the operation of high torque. To overcome the drawbacks of the conventional wrench, the inventor designs and develops the present invention through extensive researches. 
     BRIEF SUMMARY OF THE INVENTION 
     An objective of the present invention is to provide a wrench in order to allow the wrench to have excellent structural strength such that it is able to bear operations of high torque. 
     The present invention provides a high strength wrench, comprising:
         a head portion, a shaft and a handle; the head portion connected to a front end of the shaft; the handle connected to a rear end of the shaft; a driving member arranged inside the head portion;   a length of the shaft configured to be multiple times of a length of the handle;   at least one slot extending along a longitudinal direction of the shaft and formed at a circumferential surface of the shaft; a cross section shape of the shaft having a structural profile of an outer side with a relatively greater thickness and an inner portion of a relatively smaller thickness.       

     Accordingly, the shaft is able to have a greater structural strength in order to allow the wrench to bear operations of high torque. 
     Preferably, a cross section of the slot is arc-shaped in order to prevent sharp edges at the walls of the slot and the condition of stress concentration. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The following provides description of preferred embodiments of the present invention along with the accompanied drawings as described below: 
         FIG. 1  is a perspective view of a conventional ratchet wrench. 
         FIG. 2  is a perspective view of the wrench according to the first preferred embodiment of the present invention; 
         FIG. 3  is a perspective view of a bottom view of  FIG. 2 . 
         FIG. 4  is a longitudinal cross sectional view of the wrench according to the first preferred embodiment of the present invention; 
         FIG. 5  is a cross sectional view of a shaft taken along the cross sectional line  5 - 5  shown in  FIG. 4 . 
         FIG. 6  is a perspective view of the wrench according to the second preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in  FIG. 2  and  FIG. 3 , according to a first preferred embodiment of the present invention, a wrench  20  made of a metal material is provided and comprises: a head portion  30 , a shaft  40  and a handle  50 . The rear end of the head portion  30  is arranged at the front end of the shaft  40 , and the handle  50  is arranged at the rear end of the shaft  40 . In this preferred embodiment, the shaft  40  and the handle  50  are connected to each other via an integral formation method. Alternatively, they can also be manufactured individually, followed by attaching them onto each other. The head portion  30  and the shaft  40  can be integrally formed as shown in this preferred embodiment. Alternatively, they can also be formed as shown in the wrench  20 ′ of  FIG. 6 , in which the rear end of the head portion  30 ′ and the front end of the shaft  40 ′ are pivotally attached onto each other via a pivotal shaft  41  in order to allow the head portion  30 ′ to rotate relative to the shaft  40 ′. 
     A driving member  32  is arranged inside the head portion  30  and is configured to attach with and drive a fastening element of nut or bolt etc. or a socket. The driving member  32  can be an insertion column or a polygonal fitting hole or other forms. In this embodiment, the driving member is a ratchet member having a ratchet  33 , as shown in  FIG. 4 . The ratchet  33  has an insertion column  34  in order to be attached with a socket. A direction switch button  35  arranged on the head portion can be used to control a rotational direction of the ratchet  33 . The driving member  32  is not the main creation subject matter of the present invention, details thereof is omitted hereafter. The driving member includes a center C, and in this embodiment, the center C of the driving member  32  is located at the center of the insertion column  34 . 
     The shaft  40  can be a solid or hollow structure, and it has a certain length, which can be multiple times of the length of the handle  50 . As shown in  FIG. 5 , the shaft  40  has a cross section of a circular shape; one or more than one slots  42  extended along the longitudinal direction of the shaft  40  and arranged at the circumferential surface of the shaft. In this embodiment, it has two slots  42  formed to recess inward at a top edge and a bottom edge of the shaft respectively. The length of the slot  42  is slightly shorter than the length of the shaft  40 . As shown in  FIG. 5 , with the configuration of the two slots  42 , the shaft  40  has a geometric cross sectional shape of an H shape such that the shaft has a structural profile of an outer side with a relatively greater thickness and an inner portion of a relatively smaller thickness. Such type of structural profile design is able to increase the structural strength of the shaft  40  of the wrench  20  and the stress of the shaft. In addition, the cross section of each slot  42  is arc-shaped such that the inner wall of the slot has no sharp edges to prevent the concentration of stress. 
     The handle  50  can be a solid or hollow structure and has a circular cross section for the operator to hold or grip. A protruding ring  52  with a cross section of a circular shape is arranged at an intersecting area between the shaft  40  and the handle  50 . The outer diameter of the protruding ring  52  is greater than the diameter of the shaft  40 , thereby increasing the structural strength of the wrench, especially the strength of the shaft. 
     The length of the shat  40  can be multiple times of the length of the handle  50 . A shown in  FIG. 4 , for the design of the present invention, the length of the shaft is configured to be no less than two times of the length of the handle. In practice, it can be three times or more greater. Preferably, the length S of the shaft  40  is 3.1 times to 3.8 times of the length L of the handle  50 . A length M from the center C of the driving member  32  to the rear end of the shaft  40  is three to five times of the length L of the handle  50 . Preferably, it is 3.7 times to 4.5 times. 
       FIG. 6  shows a second preferred embodiment of a wrench  20 ′ of the present invention. The same components are denoted by the reference numerals used in the first preferred embodiment, and for the structural characteristics of the components, please refer to the description of the first preferred embodiment; therefore, details thereof are omitted hereafter. 
     The wrench  20 ′, similarly, includes a head portion  30 ′, a shaft  40 ′ and a handle  50 . A pivotal portion  36  at the rear end of the head portion  30 ′ is pivotally connected with a pivotal portion  46  at the front end of the shaft  40 ′. The shaft  40 ′ and the handle  50  can be solid or hollow structures. Two slots  42  are formed to longitudinally extend along the shaft at the top edge and the bottom edge of the circumferential surface of the shaft. A driving member  32 ′ is arranged in the head portion  30 ′ and the driving member  32 ′ in this embodiment is also a ratchet member having a ratchet  33 ′. The ratchet  33 ′ includes a fitting hole  38  of a polygonal shape and used to attach and drive a fastening element or a socket. A direction switch push rod  39  is arranged in the head portion in order to control the rotational direction of the ratchet  33 ′. The driving member  32 ′ also includes a center C. In this embodiment, the center C of the driving member  32 ′ is located at the center of the fitting hole  38 . Similarly, the length of the shaft  40 ′ is no less than three times of the length of the handle  50 . Preferably, the length of the shaft  40 ′ is 3.1 times to 3.8 times of the length of the handle  50 . The length from the center C of the driving member  32 ′ to the rear end of the shaft  40 ′ is approximately four times of the length of the handle, and preferably, it is 3.7 times to 4.5 times thereof. 
     The length M from the center C of the driving member  32  ( 32 ′) of the present invention to the rear end of the shaft  40  ( 40 ′) and the length L of the handle  50  form the operating moment arm (i.e. M+L) of the wrench for rotating a fastening element or a socket. The length of the shaft  40  of the wrench  20  of the present invention has a length three times greater than the shaft of a conventional wrench  10  shown in  FIG. 1 , therefore, the operating moment arm (M+L) is far longer than the moment arm of the conventional wrench  10 . With the long operating moment arm, the present invention is able to achieve high torque for rotating fastening elements, and such torque is several times greater than the torque of the conventional wrench. 
     The structural design of the wrench  20  is able to bear operations of high torque, including: the arrangement of the two slots  42  is able to allow the cross section of the shaft has a specific geometric shape such that the shaft  40  is able to bear the load of high torque without bending or damage despite its long length. In addition, the cross section of the slot  42  adopts the design of a circular arc shape such that the inner wall of the slot has no sharp edges, thereby preventing the concentration of stress and reducing the condition of broken or damaged shaft of the wrench. Moreover, the two slots are able to reduce the weight of the wrench in order to achieve labor-saving effect for the operation. 
     The aforementioned embodiments are examples disclosed to illustrate the technical features of the present invention only such that they shall not be treated as limitations of the present invention. In addition, all equivalent structural designs of the present invention shall be considered to be within the scope of the present invention.