Abstract:
A screwdriver includes a handle, a first body having an end securely mounted in the handle, a second body rotatably mounted in the first body, a ratcheting mechanism slidably mounted in a receiving section in the other end of the first body, and a switch member pivotally mounted to the other end of the first body. The switch member is pivotable between a first position and a second position to control engagement/disengagement of the ratcheting mechanism with/from teeth of the second body and to control relative rotation between the first body and the second body. A reinforcing member is provided in the receiving section to withstand high-torque operation.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a high-torque screwdriver. In particular, the present invention relates to reversible high-torque screwdriver.  
       BACKGROUND OF THE INVENTION  
       [0002]     Taiwan Utility Model Publication No. 354932 discloses a reversible high-torque screwdriver comprising a handle, a mounting seat fixed to an end of the handle, a gear wheel mounted in a longitudinal blind hole defined in the mounting seat, and a bit mounted to a square coupling hole defined in a side of the gear wheel. A pawl is received in a groove in the mounting seat and includes a first toothed section and a second toothed section for selective engagement with teeth on an outer periphery of the gear wheel. The pawl can be moved by a switch member that comprises a disc to which an elastic element is mounted. The first toothed sections of the pawl is disengaged from the gear wheel and the second toothed section is engaged with the gear wheel to allow the screwdriver to drive a fastener or the like in a first direction and to turn freely in a second direction opposite to the first direction. The position of the pawl can be switched by the switch member such that the first toothed section of the pawl is engaged with the gear wheel and that the second toothed section of the pawl is disengaged from the gear wheel to allow the screwdriver to drive the fastener in the second direction and to turn freely in the first direction.  
         [0003]     The mounting seat has a complicated shape and a small size and is thus difficult to processing. To solve this problem, the mounting seat is generally formed of zinc alloy by injection molding. The wall delimiting the groove of the mounting seat could only bear low torque imparted by the pawl, as zinc alloy is not strong. When high torque is applied to the screwdriver, the pawl made of rigid material would cause deform or fracture of the wall delimiting the groove of the mounting seat, resulting in malfunction of the screwdriver. Namely, the screwdriver in fact could not provide high-torque operation. Similar problems exist in Taiwan Utility Model Publication Nos. 527993 and M241178.  
       SUMMARY OF THE INVENTION  
       [0004]     In accordance with an aspect of the present invention, a screwdriver comprises a handle, a first body, a second body, a ratcheting mechanism, and a switch member. The first body comprises a first end securely mounted in the handle and a second end. The second end of the first body includes a receiving section and an axial hole in communication with the receiving section, the receiving section including a peripheral wall. The second body is rotatably mounted in the axial hole of the first body. A plurality of teeth are formed on an outer periphery of the second body.  
         [0005]     The ratcheting mechanism is slidably mounted in the receiving section for releasably engaging with the teeth of the second body. The switch member is pivotally mounted to the second end of the first body. The switch member is pivotable between a first position and a second position to control engagement/disengagement of the ratcheting mechanism with/from the teeth of the second body and to control relative rotation between the first body and the second body.  
         [0006]     At least one reinforcing member is mounted to the peripheral wall of the receiving section. The ratcheting mechanism presses against the at least one reinforcing member when the switch member is in one of the first position and the second position.  
         [0007]     In an example of the invention, the peripheral wall of the receiving section comprises two wall portions. The ratcheting mechanism comprises two pawls slidably mounted in the receiving section. Each pawl comprises a plurality of teeth on a side thereof for releasably engaging with the teeth of the second body. Each pawl further comprises a pressing face for releasably pressing against an associated one of the wall portions of the receiving section. An elastic element is mounted between the pawls.  
         [0008]     When the switch member is in the first position, the teeth of one of the pawls are disengaged from the teeth of the second body whereas the teeth of the other pawl are engaged with the teeth of the second body, and the pressing face of the one of the pawls is disengaged from the associated one of the wall portions of the receiving section whereas the pressing face of the other pawl presses against the associated one of the wall portions of the receiving section, allowing clockwise driving rotation and counterclockwise free rotation of the screwdriver.  
         [0009]     When the switch member is in the second position, the teeth of the one of the pawls are engaged with the teeth of the second body whereas the teeth of the other pawl are disengaged from the teeth of the second body, and the pressing face of the one of the pawls presses against the associated one of the wall portions of the receiving section whereas the pressing face of the other pawl is disengaged from the associated one of the wall portions of the receiving section, allowing counterclockwise driving rotation and clockwise free rotation of the screwdriver.  
         [0010]     Preferably, the switch member is retainable in a third position between the first position and the second position. When the switch member is in the third position, the teeth of each pawl are engaged with the teeth of the second body, and the pressing face of each pawl presses against the associated one of the wall portions of the receiving section, allowing driving rotation of the screwdriver in either direction.  
         [0011]     Preferably, the second end of the first body comprises a radial hole in communication with the axial hole. A positioning member and an elastic element are mounted in the radial hole. The switch member comprises two or three retaining grooves respectively corresponding to the two or three positions of the switch member. The positioning member is biased by the elastic element into one of the retaining grooves.  
         [0012]     Preferably, the second body comprises an axially extending coupling hole for releasably coupling with an end of a bit.  
         [0013]     Preferably, the second body comprises a groove defined in an end thereof, and a retainer is mounted in the groove for retaining the bit in place.  
         [0014]     Preferably, the screwdriver further comprises at least one washer mounted between in the handle and the first body for allowing smooth rotation of the bit.  
         [0015]     Preferably, the switch member comprises a longitudinal through-hole through which an end of the second body extends out of the switch member.  
         [0016]     In an example of the invention, the switch member comprises an end wall having an inner face. Two actuating pieces are formed on the inner face of the end wall of the switch member for selectively actuating the pawls when the switch member is moved to one of the first position and the second position.  
         [0017]     In another example of the invention, the switch member comprises an end wall and a peripheral wall. The end wall comprises a longitudinal through-hole through which an end of the second body extends out of the switch member. Two actuating pieces are formed on an inner face of the end wall of the switch member for selectively actuating the pawls when the switch member is moved to one of the first position and the second position.  
         [0018]     Preferably, the end face of the second end of the first body comprises a guide groove, and the inner face of the end wall of the switch member comprises a guide slidably received in the guide groove of the first body.  
         [0019]     Preferably, the reinforcing member is made of steel.  
         [0020]     Preferably, the second end of the first body comprises an annular groove in an outer periphery thereof. The switch member comprises an annular groove in an inner periphery thereof and a radial slot in communication with the annular groove. A C-clip is partially received in the annular groove of the first body and partially received the annular groove of the switch member, allowing the switch member to pivot relative to the first body. The C-clip comprises two ends extending into the radial slot and respectively engaging with two sidewalls delimiting the radial slot.  
         [0021]     In accordance with another aspect of the present invention, a reinforcing member is provided for a high-torque screwdriver. The reinforcing member is made of high-strength steel and mounted in a receiving section of a high-torque screwdriver. The reinforcing member is mounted between a ratcheting mechanism of the high-torque screwdriver and a peripheral wall of receiving section. The ratcheting mechanism presses against the reinforcing member such that the reinforcing member withstands the pressing force and friction force from the ratcheting mechanism when the high-strength screwdriver is turned.  
         [0022]     Other objectives, 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  
       [0023]      FIG. 1  is a perspective view of a reversible high-torque screwdriver in accordance with the present invention, wherein a bit is mounted to the screwdriver.  
         [0024]      FIG. 2  is an exploded perspective view of the reversible high-torque screwdriver in  FIG. 1 .  
         [0025]      FIG. 3  is a longitudinal cutaway view of the reversible high-torque screwdriver in  FIG. 2 .  
         [0026]      FIG. 4  is a sectional view of the reversible high-torque screwdriver in  FIG. 2 , wherein the screwdriver is in a state allowing clockwise driving rotation and counterclockwise free rotation.  
         [0027]      FIG. 5  is a sectional view similar to  FIG. 4 , wherein the screwdriver is in a state allowing driving rotation in either direction.  
         [0028]      FIG. 6  is a sectional view similar to  FIG. 4 , wherein the screwdriver is in a state allowing counterclockwise driving rotation and clockwise free rotation.  
         [0029]      FIG. 7  is a sectional view illustrating a modified embodiment of the reversible high-torque screwdriver in accordance with the present invention.  
         [0030]      FIG. 8  is a sectional view illustrating another modified embodiment of the reversible high-torque screwdriver in accordance with the present invention.  
         [0031]      FIG. 9  is a sectional view illustrating a further modified embodiment of the reversible high-torque screwdriver in accordance with the present invention.  
         [0032]      FIG. 10  is a sectional view illustrating still another modified embodiment of the reversible high-torque screwdriver in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0033]     Referring to  FIGS. 1 and 2 , a first embodiment of a reversible high-torque screwdriver in accordance with the present invention comprises a handle  10 , a first body  20 , a second body  30 , a ratcheting mechanism  90 , and a switch member  50 . The handle  10  includes a hole  11  in an end thereof.  
         [0034]     The first body  20  includes a first end  21  securely mounted in the hole  111  of the handle  10  and a second end  22  for rotatably holding the second body  30 . The first body  20  may be made of zinc alloy by injection molding for easy manufacturing purposes. As illustrated in  FIG. 3 , at least one washer  12  (two in this embodiment) is mounted between the first body  20  and the handle  10  for allowing smooth rotation of the bit  60 . In this embodiment, the washers  12  are received in a receptacle  14  defined in an end wall delimiting the hole  11  of the handle  10 .  
         [0035]     The second end  22  of the first body  20  includes a receiving section  23  and an axial hole  24  in communication with the receiving section  23 . The second end  22  of the first body  20  further includes a radial hole  25  in communication with the axial hole  24 . A positioning means  26  is mounted in the radial hole  25 . In the illustrated embodiment, the positioning means  26  includes a positioning member  261  (a ball in this embodiment) and an elastic element  262  for biasing the ball  261 . An annular groove  29  is defined in an outer periphery of the second end  22  of the first body  20 . An extension hole  27  extends from the axial hole  24  to the first end  21  of the first body  20 . The extension hole  27  is aligned with the receptacle  14  of the handle  10  when the first body  20  is mounted in the hole  11  of the handle  10 . Further, a guide groove  221  is defined in an end face of the second end  22  of the first body  20 .  
         [0036]     The second body  30  is rotatably mounted in the axial hole  24  of the second end  22  of the first body  20  and includes a first end  31  and a second end  32 . The second body  30  further includes a coupling hole  33  that extends axially and that is aligned with the extension hole  27  of the first body  20 , best shown in  FIG. 3 . Defined in the first end  31  of the second body  30  is a groove  34  into which a retainer  35  (e.g., a clip) is mounted. A plurality of teeth  36  are formed on an outer periphery of the second end  32  of the second body  30 , which will be described later.  
         [0037]     The ratcheting mechanism  90  comprises two pawls  40  that are slidably mounted in the receiving section  23 . Each pawl  40  includes a plurality of teeth  41  on a side thereof that faces the second body  30 . Each pawl  40  further includes a pressing face  42 . Each pawl  40  further includes a peg  43  on an inner end thereof that is proximal to the other pawl  40 , with two ends of an elastic element  44  respectively attached to the pegs  43  for biasing the pawls  40  away from each other.  
         [0038]     The switch member  50  is pivotally mounted to the second end  22  of the first body  20 . The switch member  50  includes an end wall  55  and a peripheral wall  56 . A longitudinal through-hole  51  is defined in the end wall  55 . Further, two actuating pieces  52  are formed on an inner face of the end wall  55  of the switch member  50  and located in the receiving section  23  of the first body  20 . As illustrated in  FIG. 4 , the actuating pieces  52  are located on outer sides of the pawls  40 . The switch member  50  further includes three retaining grooves  53  in the peripheral wall  56 .  
         [0039]     Further, an annular groove  57  is defined in an inner periphery of the peripheral wall of the switch member  50 , and a radial slot  58  is defined in the peripheral wall and in communication with the annular groove  57 . A C-clip  80  is partially received in the annular groove  29  of the first body  20  and partially received in the annular groove  57  of the switch member  50 . Thus, the switch member  50  is reliably and pivotally connected to the second end  22  of the first body  20 . Two ends  81  of the C-clip  80  are extended into the radial slot  58  of the switch member  50  and respectively engaged with two sidewalls delimiting the radial slot  58 , preventing the C-clip  80  from wobbling or swaying during operation. A guide  59  is formed on the inner face of the end wall  55  of the switch member  50  and slidably received in the guide groove  221  of the first body  20 .  
         [0040]     When the switch member  50  is in a position shown in  FIG. 4 , the ball  261  of the positioning means  26  is retained in a first one (the right one) of the retaining grooves  53  of the switch member  50  under the action of the elastic element  262 . The left pawl  40  is moved by the associated actuating piece  53  of the switch member  50  whereas the right pawl  40  is not moved. The pressing face  42  of the left pawl  40  is disengaged from a wall portion of a peripheral wall of the receiving section  23  of the first body  20  whereas the pressing face  42  of the right pawl  40  presses against another wall portion of the peripheral wall of the receiving section  23  of the first body  20 . Further, the teeth  41  of the left pawl  40  are disengaged from the teeth  36  of the second body  30  whereas the teeth  41  of the right pawl  40  are engaged with the teeth  36  of the second body  30 . Thus, the reversible high-torque screwdriver is in a state allowing clockwise driving rotation for driving a screw or the like and counterclockwise free rotation in which the screw is not driven.  
         [0041]     When the switch member  50  is turned (counterclockwise in this example) to a position shown in  FIG. 5 , the ball  261  of the positioning means  26  is retained in a second one (the middle one) of the retaining grooves  53  of the switch member  50  under the action of the elastic element  262 . None of the pawls  40  is moved by the actuating pieces  53  of the switch member  50 . The pressing faces  42  of the pawls  40  press against the associated wall portions of the receiving section  23  of the first body  20 . Further, the teeth  41  of each pawl  40  are engaged with the teeth  36  of the second body  30 . Thus, the screwdriver is in a state allowing driving rotation in either direction.  
         [0042]     When the switch member  50  is turned (counterclockwise in this example) to a position shown in  FIG. 6 , the ball  261  of the positioning means  26  is retained in a third one (the left one) of the retaining grooves  53  of the switch member  50  under the action of the elastic element  262 . The right pawl  40  is moved by the associated actuating piece  53  of the switch member  50  whereas the left pawl  40  is not moved. The pressing face  42  of the right pawl  40  is disengaged from the associated wall portion of the receiving section  23  of the first body  20  whereas the pressing face  42  of the left pawl  40  presses against the associated wall portion of the receiving section  23  of the first body  20 . Further, the teeth  41  of the right pawl  40  are disengaged from the teeth  36  of the second body  30  whereas the teeth  41  of the left pawl  40  are engaged with the teeth  36  of the second body  30 . Thus, the screwdriver is in a state allowing counterclockwise driving rotation and clockwise free rotation.  
         [0043]     It is noted that the pawls  40  and the actuating pieces  52  of the switch member  50  are concentrically mounted about the longitudinal axis of the screwdriver. The overall size of the screwdriver is reduced and movement of the pawls  40  by turning the switch member  50  is easy and reliable.  
         [0044]     Referring to  FIG. 1 , when an end of a bit  60  is inserted into the coupling hole  33  of the second body  30 , the retainer  35  mounted in the first end  31  of the second body  30  securely clamps the end of the bit  60  by the resiliency of the retainer  35 . This arrangement allows easy replacement of bits. It is noted that the washers  12  allow smooth rotation of the bit  60  when the end of the bit  60  is inserted into the coupling hole  33  of the second body  30  and in contact with the upper washer  12 .  
         [0045]     A reinforcing member  70  is mounted in the receiving section  23 . In this embodiment, the reinforcing member  70  is substantially U-shaped and in contact with the peripheral wall of the receiving section  23 . The reinforcing member  70  is made of steel or other high-strength material to reinforce the receiving section  23 .  
         [0046]     When the screwdriver is turned for driving a screw (not shown) or the like, since the reinforcing member  70  is made of high-strength material, deformation would not occur to the reinforcing member  70  and the receiving section  23  when the pressing faces  42  of the pawls  40  press against the reinforcing member  70 . A high-torque reversible screwdriver is thus obtained without the risk of slipping or large play.  
         [0047]      FIGS. 7 through 10  illustrate modified embodiments of the invention, wherein different ratcheting mechanisms  90   a ,  90   b ,  90   c ,  90   d  are illustrated. In the embodiment shown in  FIG. 7 , the ratcheting mechanism  90   a  includes four pawls  40   a  each biased by an elastic element (not labeled). Two reinforcing members  70   a  are mounted in the receiving section  23   a  of the first body  20   a  and in contact with the peripheral wall of the receiving section  23   a . The pressing faces of the pawls  40   a  press against the associated reinforcing member(s)  70   a  when the pawls  40   a  are engaged with the second body  30   a . A high-torque reversible screwdriver is thus obtained without the risk of slipping or large play.  
         [0048]     In the embodiment shown in  FIG. 8 , the ratcheting mechanism  90   b  includes two pawls  40   b  each biased by an elastic element (not labeled). A reinforcing member  70   b  is mounted in the receiving section  23   b  of the first body  20   b  and in contact with the peripheral wall of the receiving section  23   b  of the first body  20   b . The pressing faces of the pawls  40   b  of the ratcheting mechanism  90   b  press against the reinforcing member  70   b  when the pawls  40   b  are engaged with the second body  30   b . A high-torque reversible screwdriver is thus obtained without the risk of slipping or large play.  
         [0049]     In the embodiment shown in  FIG. 9 , the ratcheting mechanism  90   c  includes four pawls  40   c  each biased by an elastic element (not labeled). Two reinforcing member  70   c  are mounted in the receiving section  23   c  of the first body  20   c  and in contact with the peripheral wall of the receiving section  23   c  of the first body  20   c . The pressing faces of the pawls  40   c  of the ratcheting mechanism  90   c  press against the associated reinforcing member(s)  70   c  when the pawls  40   c  are engaged with the second body  30   c . A high-torque reversible screwdriver is thus obtained without the risk of slipping or large play.  
         [0050]     In the embodiment shown in  FIG. 10 , the ratcheting mechanism  90   d  includes two pawls  40   d  biased by an elastic element (not labeled). Two reinforcing member  70   d  are mounted in the receiving section  23   d  of the first body  20   d  and in contact with the peripheral wall of the receiving section  23   d  of the first body  20   d . The pressing faces of the pawls  40   d  of the ratcheting mechanism  90   d  press against the associated reinforcing member(s)  70   d  when the pawls  40   d  are engaged with the second body  30   d . A high-torque reversible screwdriver is thus obtained without the risk of slipping or large play.  
         [0051]     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.