Patent Publication Number: US-8522652-B2

Title: Spring for a ratchet wrench

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a spring for a ratchet wrench and, more particularly, to a spring that provides enhanced movement stability and that reduces the costs of a ratchet wrench using the spring. 
       FIG. 5  shows a conventional ratchet wrench including a body  1 ′, a ratchet wheel  2 ′, a pawl  3 ′, a pressing member  4 ′, a spring  5 ′, and a switch  6 ′. The body  1 ′ includes a compartment  11 ′ receiving the ratchet wheel  2 ′ and the pawl  3 ′. The ratchet wheel  2 ′ is rotatable relative to the body  1 ′ and includes a plurality of teeth  21 ′ on an outer periphery thereof. A coupling portion  22 ′ is provided on a central portion of the ratchet wheel  2 ′ for coupling with a tool such as a socket. The pawl  3 ′ is pivotably mounted to the body  1 ′ and includes a first side having a toothed section  31 ′ for engagement with the teeth  21 ′ of the ratchet wheel  2 ′ and a second side having a pressing face  32 ′. The pressing member  4 ′ is made of a rigid material and presses against the pressing face  32 ′. The spring  5 ′ is a compression spring and includes a first end pressing against the pressing member  4 ′ and a second end engaged with the switch  6 ′. The switch  6 ′ is pivotably mounted to the body  1 ′ and can be pivoted to move the spring  5 ′ and the pressing member  4 ′. The pressing member  4 ′ presses against the pressing face  32 ′ of the pawl  3 ′ and causes pivotal movement of the pawl  3 ′ between first and second positions. The toothed portion  31 ′ is engaged with the teeth  21 ′ of the ratchet wheel  2 ′ so that the ratchet wheel  2 ′ can only rotate in a first direction when the pawl  3 ′ is in the first position and that the ratchet wheel  2 ′ can only rotate in a second direction reverse to the first direction when the pawl  3 ′ is in the second position. 
     However, positioning of the pressing member  4 ′ on the first end of the spring  5 ′ is not reliable. Namely, the pressing member  4 ′ is liable to fall from the spring  5 ′. Furthermore, actuation of the pawl  3 ′ requires transmission of the spring  5 ′ and the pressing member  4 ′ such that the switching movement is not smooth due to a shift in the contact position between the pressing member  4 ′ and the spring  5 ′. 
     BRIEF SUMMARY OF THE INVENTION 
     An objective of the present invention is to provide a ratchet wrench having enhanced movement stability and reduced costs. 
     A ratchet wrench according to the present invention includes a body, a ratchet wheel, a pawl, a pressing member, and a spring. The ratchet wheel is received in a compartment of the body and rotatable relative to the body. The ratchet wheel includes a plurality of teeth on an outer periphery thereof. The pawl is received in the compartment and movable relative to the body. The pawl includes a first side having a toothed section for engagement with the plurality of teeth of the ratchet wheel and a second side having a pressing face. The switch is pivotably mounted to the body and operatively connected to a first end of the spring. The switch is operable to cause a second end of the spring to press against the pressing face of the pawl, causing pivotal movement of the pawl between first and second positions. The toothed portion is engaged with the plurality of teeth of the ratchet wheel so that the ratchet wheel can only rotate in a first direction when the pawl is in the first position and that the ratchet wheel can only rotate in a second direction reverse to the first direction when the pawl is in the second position. The spring is a helical compression spring including the first and second ends and an intermediate section between the first and second ends. Each of the first and second ends and the intermediate section includes a plurality of adjoining turns. The plurality of adjoining turns of the intermediate section is spaced from each other and forms a compressible portion. The plurality of adjoining turns of the second end of the spring abuts against each other and has no gaps therebetween. 
     Preferably, the plurality of adjoining turns of the first end of the spring abuts against each other and has no gaps therebetween. 
     The present invention will become clearer in light of the following detailed description of illustrative embodiments of this invention described in connection with the drawings. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an exploded perspective view of a ratchet wrench according to the present invention. 
         FIG. 2  shows a perspective view of a spring of the ratchet wrench of  FIG. 1 . 
         FIG. 3  shows a partial, cross sectional view of the ratchet wrench of  FIG. 1 . 
         FIG. 4  shows a cross sectional view similar to  FIG. 3 , with a pawl moved to another position upon operation of a switch. 
         FIG. 5  shows a partial, cross sectional view of a conventional ratchet wrench. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIGS. 1-3 , a ratchet wrench according to the present invention includes a body  1 , a ratchet wheel  2 , a pawl  3 , a pressing member  4 , and a spring  5 . The body  1  includes a compartment  11  receiving the ratchet wheel  2  and the pawl  3 . The body  1  further includes a push pin  12  and a positioning device  13  in the form including a retainer cap  131  and a C-ring  132 . The push pin  12  and the positioning device  13  are conventional. The ratchet wheel  2  is received in the compartment  11  and rotatable relative to the body  1 . The ratchet wheel  2  includes a plurality of teeth  21  on an outer periphery thereof. A coupling portion  22  is provided on a side of the ratchet wheel  2  for coupling with a tool such as a socket. Disengagement of the socket from the coupling portion  22  can be controlled by operating the push pin  12 , which is conventional. The pawl  3  is received in the compartment  11  and movable relative to the body  1 . The pawl  3  includes a first side having a toothed section  31  for engagement with the teeth  21  of the ratchet wheel  2  and a second side having a pressing face  32 . The switch  4  is pivotably mounted to the body  1  and includes a receptacle  41  receiving the spring  5 . 
     With reference to  FIGS. 2-4 , the spring  5  is a helical compression spring and includes two ends  51  and  52  and an intermediate section  53  between the ends  51  and  52 . Each of the ends  51  and  52  and the intermediate section  53  includes a plurality of adjoining turns  511 ,  521 , and  531 . The adjoining turns  531  of the intermediate section  53  are spaced from each other (see gaps  532  between adjacent turns  531 ) and form a compressible portion a. The adjoining turns  511 ,  521  of each end  51 ,  52  of the spring  5  abut against each other and have no gaps therebetween. Thus, each end  51 ,  52  is not easy to deform. Furthermore, the spring  5  can be mounted without considering the direction of the spring  5 . Namely, either end  51 ,  52  can press against the pawl  3  to provide sufficient pressing strength, providing enhanced assembling convenience. In the form shown, the end  51  of the spring  5  presses against the pawl  3 . However, the spring  5  can be mounted in a reverse direction to press against the pawl  3  by the other end  52 . 
     The switch  4  and can be pivoted to move the spring  5  that presses against the pressing face  32  of the pawl  3  and causes pivotal movement of the pawl  3  between first and second positions. The toothed portion  31  is engaged with the teeth  21  of the ratchet wheel  2  so that the ratchet wheel  2  can only rotate in a first direction when the pawl  3  is in the first position and that the ratchet wheel  2  can only rotate in a second direction reverse to the first direction when the pawl  3  is in the second position. 
     After assembly, since deformation of the end  51  of the spring  5  is not easy, the pawl  3  can be moved by the spring  5  when the switch  4  is pivoted for changing the operative direction of the ratchet wrench. The compressible intermediate section  53  of the spring  5  assures reliable engagement between the pawl  3  and the ratchet wheel  2  while the pawl  3  and/or the ratchet wheel  2  are moved. The pressing member required in the conventional design is not used. Thus, the costs are reduced, and the assembling inconvenience is mitigated. Furthermore, the operational stability is enhanced due to direct pressing against the pawl  3  by the spring  5 . 
     It can be appreciated that only one of the ends  51  and  52  of the spring  5  having adjoining turns  511 ,  521  is sufficient to achieve the above advantages. Furthermore, the ratchet wheel  2 , the pawl  3 , and the switch  4  can be of other shapes and structures different from those shown in the drawings. 
     Although specific embodiments have been illustrated and described, numerous modifications and variations are still possible without departing from the essence of the invention. The scope of the invention is limited by the accompanying claims.