Patent Publication Number: US-2004055423-A1

Title: Reversible ratcheting tool with a smaller head and improved driving torque

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
     [0001] This application is a continuation of U.S. application Ser. No. 10/219,135, filed Aug. 15, 2002 and still pending, which is a divisional application of U.S. application Ser. No. 09/523,625 filed Mar. 13, 2000, now U.S. Pat. No. 6,457,387. Both U.S. application Ser. No. 10/219,135 and U.S. Pat. No. 6,457,387 are hereby incorporated by reference in their entirety. 
    
    
     
       BACKGROUND OF THE INVENTION  
       [0002] 1. Field of the Invention  
       [0003] The present invention relates to a reversible ratcheting tool having a smaller head and improved driving torque for convenient use in a limited space.  
       [0004] 2. Description of the Related Art  
       [0005] A wide variety of ratcheting tools have heretofore been disclosed. Typical examples include: U.S. Pat. No. 1,957,462 to Kress issued on May 8, 1934; U.S. Pat. No. 4,328,720 to Shiel issued on May 11, 1982; U.S. Pat. No. 5,626,062 to Colvin issued on May 6, 1997; U.S. Pat. No. 4,762,033 to Chow issued on Aug. 9, 1988; U.S. Pat. No. 4,520,697 to Moetteli issued on Jun. 4, 1985; U.S. Pat. No. 3,337,014 to Sandrick issued on Aug. 22, 1967; and U.S. Pat. No. 5,144,869 to Chow issued on Sep. 8, 1992. Most of the above-mentioned conventional ratcheting tools fail to provide high torque operation, as the pawls merely engage with the ratchet wheel by at best three or five teeth. The head of the ratcheting tool has to be relatively large for accommodating those components and thus is difficult to be used in a limited space. In addition, the pawl is directly driven by the switch button or reverser plate or like element such that the pawl tends to be disengaged from the ratchet wheel or like element if the switch block is inadvertently impinged. Generally, a skilled user uses a combination wrench, a spanner with two open ends, or a ring spanner for tightening or loosening a fastener in a limited space. Yet, it is found that free rotation of the ratcheting tool during ratcheting is too large (larger than the theoretic value of 5°), as the pawl has a long travel.  
       [0006] U.S. Pat. No. 6,431,031 issued on Aug. 13, 2002 discloses a reversible ratcheting tool with a smaller head to solve the above problems.  
       [0007]FIG. 8 illustrates engagement between a gear wheel  80  and a pawl  81  of a conventional ratcheting tool. The pawl  81  has a plurality of teeth engaged with teeth  83  of the gear wheel  80  at faces  82  so as to provide high torque operation. The faces  82  have a center of curvature at “B”, which is coincident with the center of the gear wheel  80 . Referring to FIG. 9, when the handle (not shown) is rotated clockwise, the gear wheel  80  exerts a force F on each tooth on the pawl  81 . T he force F is imparted into a downward vertical force F1 and a leftward horizontal force F2. The leftward horizontal force F2 makes the pawl  81  bear against point A on a wall in a cavity in a web area of the handle. The downward vertical force F1 moves the pawl  81  away from the gear wheel  80 . As a result, the right portion of the pawl  81  is disengaged from the gear wheel  80 . The reactive force by the wall at point A is imparted into an upward vertical force FN1 and a rightward horizontal force FN2. The upward vertical force FN1 makes the pawl  81  move toward the gear wheel  80  and the rightward horizontal force FN2 moves the pawl  81  rightward. As a result, the pawl  81  and the gear wheel  80  have a firm engagement with each associated tooth of the gear wheel at point D.  
       [0008] Referring to FIG. 10, when the handle is further rotated clockwise, a higher torque is applied such that the magnitudes of the forces F1 and F2 increase. The right portion of the pawl teeth that is slightly disengaged from the gear wheel teeth  83  can still be in contact with the gear wheel teeth  83  when the gear wheel  80  is rotated. The right portion of the pawl  81  is moved downward farther. As a result, more teeth on the pawl  81  are disengaged from the gear wheel  80  (see the pawl teeth on the right side of point A). The forces FN1 and FN2 are also increased in magnitude, yet fewer pawl teeth have firm engagement with the gear wheel teeth. This problem is aggravated when the handle is further rotated clockwise. Accordingly, the gear wheel/pawl arrangement fails to provide the required high torque operation, as all of the pawl teeth have the same center of curvature. In addition, the pawl and the gear wheel will be damaged quickly.  
       [0009] The present invention is intended to provide an improved design in this regard to improve the driving torque for reliable high-torque operation.  
       SUMMARY OF THE INVENTION  
       [0010] It is a primary object of the present invention to provide a reversible ratcheting tool with a small head while providing improved driving torque for convenient use in a limited space.  
       [0011] A ratcheting tool in accordance with the present invention comprises:  
       [0012] a handle;  
       [0013] a head extended from the handle and having a compartment therein;  
       [0014] a drive member including a first end extended beyond the compartment, a second end extended beyond the compartment, and a gear wheel formed between the first end and the second end, the gear wheel being rotatably mounted in the compartment and including an outer periphery with a plurality of first teeth;  
       [0015] a pawl mounted in the compartment and including a first side with a plurality of second teeth facing the first teeth of the gear wheel and a second side facing away from the gear wheel, the second teeth of the pawl including a first teeth portion having a first center of curvature and a second teeth portion having a second center of curvature located at a position different from the first center of curvature;  
       [0016] a ring mounted in the compartment and around the first end of the drive member, the ring being operably connected to the pawl such that the ring and the pawl are pivotable about a rotational axis of the gear wheel and that the pawl is movable in a radial direction relative to the ring;  
       [0017] a reversing plate mounted to the first end of the drive member and pivotable about the rotational axis of the gear wheel between a first position and a second position;  
       [0018] means for retaining the reversing plate in position; and  
       [0019] means for providing transmission between the reversing plate and the pawl for moving the pawl between a first ratcheting position and a second ratcheting position, wherein the first teeth portion of the pawl is engaged with the first teeth of the gear wheel for ratcheting in a first direction and the second teeth portion of the pawl is disengaged from the first teeth of the gear wheel when the pawl is in the first ratcheting position, and wherein the second teeth portion of the pawl is engaged with the first teeth of the gear wheel for ratcheting in a second direction opposite to the first direction and the first teeth portion of the pawl is disengaged from the first teeth of the gear wheel when the pawl is in the second ratcheting position.  
       [0020] The first center of curvature of the pawl is coincident with a center of the gear wheel when the pawl is in the first ratcheting position. The second center of curvature of the pawl is coincident with the center of the gear wheel when the pawl is in the second ratcheting position. Thus, the total number of pawl teeth actually and reliably engaged with the gear wheel in accordance with the present invention during ratcheting is greater than that in conventional designs, and such advantage is the result of the novel design in the first and second teeth portions of the pawl.  
       [0021] Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0022]FIG. 1 is a perspective view of a reversible ratcheting tool in accordance with the present invention.  
     [0023]FIG. 2 is an exploded perspective view of the reversible ratcheting tool in FIG. 1.  
     [0024]FIG. 2A is a schematic view, in an enlarged scale, illustrating a pawl of the reversible ratcheting tool in accordance with the present invention.  
     [0025]FIG. 2B is an enlarged perspective view illustrating a reversing plate of the reversible ratcheting tool in accordance with the present invention.  
     [0026]FIG. 2C is an enlarged perspective view illustrating a ring of the reversible ratcheting tool in accordance with the present invention.  
     [0027]FIG. 3 is a top sectional view, in an enlarged scale, of an end portion of the reversible ratcheting tool in FIG. 1, wherein the ratcheting tool is in a status allowing free rotation.  
     [0028]FIG. 3A is a schematic view, in an enlarged scale, illustrating engagement between a gear wheel and the pawl of the reversible ratcheting tool in accordance with the present invention, wherein the ratcheting tool is in a status allowing free rotation.  
     [0029]FIG. 4 is a sectional view similar to FIG. 3, wherein the reversible ratcheting tool is in a status allowing clockwise ratcheting.  
     [0030]FIG. 4A is a view similar to FIG. 3A, wherein the ratcheting tool is in a status allowing clockwise ratcheting.  
     [0031]FIG. 5 is a sectional view similar to FIG. 3, wherein the reversible ratcheting tool is in a status allowing counterclockwise ratcheting.  
     [0032]FIG. 5A is a view similar to FIG. 3A, wherein the ratcheting tool is in a status allowing counterclockwise ratcheting.  
     [0033]FIG. 6 is a sectional view taken along line  6 - 6  in FIG. 4.  
     [0034]FIG. 7 is a sectional view taken along line  7 - 7  in FIG. 4.  
     [0035]FIG. 8 is a schematic view illustrating engagement between a gear wheel and a pawl of a conventional ratcheting tool.  
     [0036]FIG. 9 is a view similar to FIG. 8, wherein a handle of the conventional ratcheting tool is rotated clockwise.  
     [0037]FIG. 10 is a view similar to FIG. 9, wherein the handle is further rotated clockwise. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0038] Referring to FIGS. 1, 2, and  6 , a ratcheting tool in accordance with the present invention is designated by  10  and has a handle  11  and a head  12  extended from the handle  11 . The head  12  is substantially circular and has a minimized volume. The head  12  includes a compartment  13  consisting of a relatively larger first compartment section  131  and a relatively smaller second compartment section  132 . A top face (not labeled) of the head  12  includes an opening  14  consisting of a circular opening section  141  that is concentric with the first compartment section  131  and a rectangular opening section  142 . The top face of the head  12  further includes a hole  16  adjacent to the opening section  142 . Defined in a lower end of the head  12  is a circular hole  15  that is concentric with the first compartment section  131  and has a diameter the same as that of the first compartment section  131 . The lower end of the head  12  is formed with a ledge  18  (FIG. 6) that defines a portion of the second compartment section  132 .  
     [0039] Rotatably mounted in the head  12  is a drive member  20  having an upper end  22 , a drive column  23  on a lower end thereof, and a gear wheel  21  formed in an intermediate portion thereof. The gear wheel  21  is rotatably received in the first compartment  131  of the head  12  and includes teeth  211  formed on an outer periphery thereof. The upper end  22  of the drive member  20  includes an engaging groove  221 , and an annular groove  222  is defined in a side of the gear wheel  21 . The drive column  23  includes a hole  231  for receiving a ball  232 . The drive member  20  further includes a central through-hole  24  with a shoulder portion  241 , which will be described later.  
     [0040] Still referring to FIGS. 1, 2, and  6 , a pushpin  25  is mounted in the through-hole  24  of the drive member  20  and includes an enlarged upper end  251  for manual pressing. A lower end of the pushpin  25  includes a stepped groove  252  for receiving a portion of the ball  232  when the pushpin  25  is pushed, thereby allowing disengagement of the drive column  23  from a socket (not shown). An elastic member  253  is mounted around the pushpin  25  and attached between the shoulder portion  241  of the through-hole  24  and the enlarged end  251  of the pushpin  25 . The elastic member  253  biases the pushpin  25  upward for moving the ball  232  outward to an engaging position for engaging with a socket, which is conventional and therefore not further described. The ball  232  in the engaging position is engaged with the stepped groove  252  to thereby prevent disengagement of the pushpin  25 .  
     [0041] A pawl  30  is mounted in the second compartment section  132  and includes a side facing the gear wheel teeth  211 . Referring to FIG. 2A, the side of the pawl  30  has a plurality of teeth (ten teeth in this embodiment) for engaging with the gear wheel teeth  211 , thereby providing reliable mesh therebetween. The pawl  30  includes a recess  33  on a top thereof. Of more importance, as illustrated in FIG. 2A, the teeth on the side of the pawl  30  includes a first teeth portion  31  having a center of curvature at “E” and a second teeth portion  32  having a center of curvature at “F”. Namely, the centers of curvatures for the teeth portions  31  and  32  are located at different positions “E” and “F”, the purpose of which will be described later. The first teeth portion  31  and the second teeth portion  32  may be arranged in a continuous or noncontinuous manner. The side of the pawl  30  also includes first and second faces  34 ,  35  extending outwardly on opposite sides of the plurality of teeth and interconnected to the other side of the pawl.  
     [0042] Still referring to FIGS. 1, 2, and  6 , a ring  40  is pivotally mounted around the upper end  22  of the drive member  20 . As illustrated in FIG. 2C, a tip piece  41  projects outward from the ring  40  and is engaged in the recess  33  of the pawl  30  to move therewith. A notch  42  is defined in an inner periphery of the ring  40  and aligned with the annular groove  222  of the drive member  20 . The notch  42  of the ring  40  further includes an enlarged section  43 , which will be described later.  
     [0043] A reversing plate  50  is mounted around the upper end  22  of the drive member  20  and includes a hole  51  and a thumb piece  52 . As illustrated in FIG. 6, the enlarged upper end  251  of the pushpin  25  extends through the circular opening section  141  of the head  12  and beyond the hole  51  of the reversing plate  50  for manual operation. Referring to FIG. 2B, a positioning piece  511  projects radially inward from an inner periphery of the hole  51  of the reversing plate  50  in a portion adjacent to the thumb piece  52 . The inner periphery of the hole  51  of the reversing plate  50  further includes a cavity  512  facing the positioning piece  511 . A C-clip  53  is mounted around a portion of the engaging groove  221  of the upper end  22  of the drive member  20 , thereby retaining the upper end  22  of the drive member  20  to the top face of the head  12 . The C-clip  53  is partially accommodated in the cavity  512  of the reversing plate  50 . In addition, the positioning piece  511  is extended into the remaining portion of the engaging groove  221  of the drive member  20 . Thus, the reversing plate  50  is pivotally mounted to the upper end  22  of the drive member  20 . The thumb piece  52  of the reversing plate  50  further includes two through-holes  521  and  522 . An arcuate groove  523  is defined in an underside of the thumb piece  52  and communicated with the through-hole  521 . The thumb piece  52  includes a receptacle  524  that is communicated with the arcuate groove  523 . A retainer block  54  is formed on a bottom of the reversing plate  50  and projects downward from a position between the through-hole  522  and the hole  51 . The retainer block  54  includes a lower end  541  that is pivotally movable in the enlarged section  43  of the ring  40 , which will be described later.  
     [0044] A retaining means  60  is mounted in the receptacle  524  of the thumb piece  52  and includes a substantially U-shape slide piece  61  and an elastic member  62 . The slide piece  61  includes a tapered push-face  611  consisting of two faces (not labeled) separated by a tip (not labeled, see FIG. 2). The elastic member  62  is received between two limbs (not labeled) of the U-shape slide piece  61 . In practice, an end face of the receptacle  524  is pressed to form a configuration for preventing disengagement of the elastic member  62  from the receptacle  524  yet allowing movement of the slider piece  61  relative to the elastic member  62 .  
     [0045] A pin  5211  is inserted through the through-hole  521  of the thumb piece  52  with a lower end of the pin  5211  extended through the arcuate groove  523  and into the hole  16  of the head  12 . Thus, the pin  5211  is retained in the hole  16 . As a result, the arcuate groove  523  is movable relative to the pin  5211  during pivotal movement of the reversing plate  50 . The push-face  611  of the slide piece  61  may retain the pin  5211  in place. In addition, as the pin  5211  is retained in place and the positioning piece  511  of the reversing plate  50  is engaged in the engaging groove  221  of the drive member  20 , the reversing plate  50  is securely yet pivotally engaged with the upper end  22  of the drive member  20 .  
     [0046] A transmission member  70  is provided to convert manual pivotal movement of the reversing plate  50  into pivotal movement of the pawl  30  about the rotational axis of the gear wheel  21 . In this embodiment, the transmission member  70  is in the form of a spring having a relatively small pitch. The transmission member  70  is extended in the through-hole  522  of the reversing plate  50 , the rectangular opening section  142  of the head  12  of the handle  11 , and the notch  42  of the ring  40  and then into the annular groove  222  of the drive member  20 .  
     [0047] When the reversing plate  50  is in a position shown in FIG. 4, a face (upper one in FIG. 4) of the push-face  611  of the slide piece  61  bears against the pin  5211  under the action of the elastic member  62 . The other side of the pawl  30  facing away from the teeth  31  bears against a wall portion defining the second compartment section  132 . Thus, the teeth  31  of the pawl  30  is forced to engage with the teeth  211  of the gear wheel  21  of the drive member  20 , best shown in FIG. 6. The ratcheting tool is now in a status for driving a socket (not shown) or the like clockwise. The handle of the ratcheting tool may be moved counterclockwise without disengaging the drive member  20  from the socket. Thus, the ratcheting tool may be used in a relatively small space, as the head  12  of the ratcheting tool is relatively small due to the provision of the concentric design of the gear wheel  21  and the reversing plate  50 . As illustrated in FIG. 7, the through-hole  522  of the thumb piece  52  is slightly offset from the notch  42  of the ring  40 . The transmission member  70  is thus in a zigzag status to provide excellent resiliency in the transverse direction for providing the required transmission.  
     [0048] Referring to FIG. 4A, the pawl  30  bears against a point “G” of a left wall portion defining the second compartment section  132 . It is noted that the center of curvature E of the first teeth portion  31  of the pawl  30  is coincident with a center of the gear wheel  21 . Thus, all teeth of the first teeth portion  31  are completely engaged with the gear wheel teeth  211  and the second teeth portion  32  is disengaged from the gear wheel teeth  211 , as the center of curvature F of the second teeth portion  32  of the pawl  30  is at a different location. When the handle  11  of the ratcheting tool  10  is rotated clockwise, no force is applied to the second teeth portion  32  of the pawl  30  and there is no reactive force accordingly. Thus, it is the first teeth portion  31  of the pawl  30  that reliably engages with the gear wheel teeth  211  during the clockwise rotation of the handle  11 , thereby providing reliable high-torque operation. It is noted that force transmitted from the gear wheel  21  is uniformly distributed to all of the teeth of the first teeth portion  31 . The total number of pawl teeth actually and reliably engaged with the gear wheel in accordance with the present invention is greater than that in conventional design.  
     [0049] When the reversing plate  50  is moved to a position shown in FIG. 3, the tip of the push-face  611  of the slide piece  61  bears against the pin  5211  under the action of the elastic member  62 . The ring  40  is also pivoted via transmission of the transmission member  70 . The pawl  30  is moved away from the gear wheel  21 , as the tip piece  41  of the ring  40  is engaged in the recess  33  on the top face of the pawl  30 . Thus, the pawl  30  is moved to a middle portion of the second compartment section  132  and thus disengaged from the teeth  211  of the gear wheel  21 . As a result, the ratcheting tool is incapable of driving the socket. Referring to FIG. 3A, only one or two of each pawl teeth portion  31 ,  32  are engaged with the gear wheel teeth  211 , the remaining pawl teeth are disengaged from the gear wheel teeth  211 .  
     [0050] When the reversing plate  50  is moved to a position shown in FIG. 5 by manually pushing the thumb piece  52 , the slide piece  61  is moved away from the gear wheel  21  and compresses the elastic member  62 . Thus, the pin  5211  may slide over the push-face  611  of the slide piece  61  to the other face of the push-face  611 . The other side of the pawl  30  facing away from the teeth portions  31  and  32  bears against another portion defining the second compartment section  132 . Thus, the teeth of the pawl  30  are forced to reengage with the teeth  211  of the gear wheel  21  of the drive member  20  (see FIG. 6). The ratcheting tool is now in a status for driving the socket counterclockwise. It is appreciated that the pawl  30  is pivoted during pivotal movement of the thumb piece  52  via transmission of the transmission member  70  and the ring  40  that engages with the pawl  30 .  
     [0051] Referring to FIG. 5A, the pawl  30  bears against a point “H” of a right wall portion defining the second compartment section  132 . Now the center of curvature F of the second teeth portion  32  of the pawl  30  is coincident with the center of the gear wheel  21 . Thus, all teeth of the second teeth portion  32  are completely engaged with the gear wheel teeth  211  and the first teeth portion  31  is disengaged from the gear wheel teeth  211 , as the center of curvature E of the first teeth portion  31  of the pawl  30  is at a different location. When the handle  11  of the ratcheting tool  10  is rotated counterclockwise, no force is applied to the first teeth portion  31  of the pawl  30  and there is no reactive force accordingly. Thus, it is the second teeth portion  32  of the pawl  30  that reliably engages with the gear wheel teeth  211  during the clockwise rotation of the handle  11 , thereby providing reliable high-torque operation. It is noted that force transmitted from the gear wheel  21  is uniformly distributed to all of the teeth of the second teeth portion  32 . The total number of pawl teeth actually and reliably engaged with the gear wheel in accordance with the present invention is greater than that in conventional design.  
     [0052] Referring to FIG. 6, it is noted that the retainer block  54  of the reversing plate  50  is in contact with a portion of the transmission member  70  to prevent disengagement and over-distortion of the transmission member  70 . The lower portion  541  of the retainer block  54  is pivotally received in the enlarged section  43  of the notch  42  such that the retainer block  54  can be pivoted when the reversing plate  50  is pivoted.  
     [0053] It is appreciated that the pawl  30  engages with the gear wheel  21  by ten (10) teeth and thus may bear higher torque during ratcheting. It is noted that the push-face  611  of the slide piece  61 , under the action of the elastic member  62 , retains the ring  40  as well as the pawl  30  in place to provide reliable ratcheting. Yet, the tip piece  41  of the ring  40  and the recess  33  of the pawl  30  are configured to allow the pawl  30  to be moved away from the gear wheel  21  in a radial direction during non-driving rotation of the handle. Accordingly, the user must apply a relatively larger force to switch the reversing plate  50 , yet this also prevents inadvertent impingement to the thumb piece  52  that may cause undesired movement of the pawl  30 .  
     [0054] According to the above description, it is appreciated that the ratcheting tool in accordance with the present invention may bear much higher torque and has minimized head size that is very useful when operating in a limited space. In addition, the ratcheting direction can be changed by easy operation of the reversing plate. The arrangement for achieving the ratcheting direction switching is simple yet requires a relatively larger force to prevent inadvertent switching. Of more importance, the total number of pawl teeth actually and reliably engaged with the gear wheel in accordance with the present invention during ratcheting is greater than that in conventional design, and such advantage is the result of the novel design in the first and second teeth portions  31  and  32  of the pawl  30 .  
     [0055] Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.