Patent Publication Number: US-6666112-B2

Title: Switching arrangement for a reversible ratchet type wrench

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a switching arrangement for a reversible ratchet-type wrench to provide reliable ratcheting and to allow easy assembly and manufacture. 
     2. Description of the Related Art 
     Several factors are considered in designing wrenches and spanners, including improving the torque-bearing capacity, providing as many teeth as possible for the drive member, and providing an easy-to-manufacture structure. U.S. Pat. No. 2,957,377 issued to Hare on Oct. 25, 1960 discloses a reversible ratchet type wrench comprising a body  10  having a handle  11  and a head  12 . A cap  39  and an annular wall  44  are provided to upper side and lower side of the head  12 , respectively. Yet, this increases the assembly time and the manufacture cost and adversely affects the appearance. A shifting lever  35  is retained in place by a spring  33  that is located in a cylindrical opening  34 . Nevertheless, formation of the cylindrical opening  34  that extends upward at an incline is relatively difficult. In addition, formation of the cavity  16  having converging straight sides  17 ,  18  which diverge in the direction of the periphery of rotatable member  14  requires expensive and accurate computer-numeric-control (CNC), which further results in an increase in the cost together with a low production rate. This is why such a reversible ratchet type wrench is hardly seen in the market. 
     FIGS. 13 and 14 illustrate another conventional ratchet type wrench comprising a handle  12 ′ and a head  11 ′. The head  11 ′ is machined to form four consecutive compartments for receiving the drive member  20 ′, the pawl  30 ′ and the shifting lever  40 ′, wherein three of the compartments can be formed by cutting, yet the remaining one must be machined by CNC. Further, the resultant head structure is relatively weak and thus has a poor torque-bearing capacity. In addition, the movement of the pawl  30 ′ for changing ratcheting direction is found unreliable, as it is achieved via transmission of the hook end  442 ′ of a spring  44 ′ attached to the shifting lever  40 ′. 
     FIG. 15 of the drawings illustrates a conventional wrench of the type having a handle B′ and a head in which a drive member A′ is rotatably received. A pawl D′ is slidably received in a transverse through-hole C′ in a web between the handle B′ and the head. However, an end of the pawl D′ extends beyond the transverse through-hole C′ and thus adversely affects operation of the wrench when used in a limited space. A two-pawl type wrench was proposed to solve this problem. As illustrated in FIGS. 16 through 18, the two-pawl type wrench includes a handle  1 ′ and a head  11 ′ extended from the handle  1 ′. A drive member  2 ′ is rotatably received in the head  11 ′, a receptacle  121 ′ is defined in a web  12 ′ between the handle  1 ′ and the head  11 ′, and a spring-biased switch member  4 ′ is mounted in a cavity  13 ′ in the web  12 ′. Two spaced pawls  3 ′ are received in the receptacle  121 ′ and are biased by two springs  6 ′, respectively. A threaded end cap  5 ′ is engaged with a threaded outer end of the receptacle  121 ′ to enclose the pawls  3 ′ and springs  6 ′. As illustrated in FIGS. 17 and 18, the switch member  4 ′ is turned to bias one of the pawls  3 ′ to engage its teeth  31 ′ with the drive member  2 ′ to thereby change the ratcheting direction of the wrench. However, it was found that the switch member  4 ′ cannot be reliably retained in place and thus tends to disengage from the cavity  13 ′. In addition, the pawl  3 ′ engaged with the drive member  2 ′ is not engaged with an inner longitudinal wall that defines the transverse through-hole and that faces the drive member  2 ′. As a result, the torque-bearing capacity of the wrench is poor. Furthermore, the outer pawl  3 ′ (FIGS. 17 and 18) tends to be stuck when the threaded end cap  5 ′ is mounted too close to the switch member  4 ′. To the contrary, if the threaded end cap  5 ′ is too far away from the switch member  4 ′, the pawl  3 ′ cannot be firmly engaged with the drive member  2 ′. Further, the threaded end cap  5 ′ tends to be disengaged from the drive member  2 ′, as the former is in threading engagement with the threaded outer end of the receptacle  121 ′. 
     FIGS. 19 through 21 illustrate another conventional wrench having a substantially V-shape transverse through-hole  25 ′ in a web between a handle  20 ′ and a head  21 ′ thereof. The head  21 ′ includes a compartment in which a drive member  22 ′ is rotatably received. A spring-biased pawl  23 ′ is received in each limb of the V-shape transverse through-hole  25 ′. A switch member  30 ′ includes a stem  35 ′ pivotally received in a cavity  24 ′ in the web and a thumb-piece  32 ′ extending from the stem  35 ′ for manual operation, thereby switching the switch member  30 ′ between two positions corresponding to two opposite ratcheting direction of the wrench. The thumb piece  32 ′ of the switch member  30 ′ includes a downwardly facing receptacle  36 ′ (FIG. 21) for receiving a spring  37 ′ and a ball  38 ′ that is biased by the spring  37 ′ to be positioned in one of two positioning recesses  281 ′ (FIG. 20) in a sector-like recessed area  28 ′ (FIG. 19) of the web. The switch member  30 ′ may be retained in place reliably. However, a C-clip  33 ′ is required for mounting the switch member  30 ′ in place, which adversely affects the aesthetically pleasing effect. In addition, processing of the sector-like recessed area  28 ′ in the web and the V-shape transverse through-hole  25 ′ is difficult. Mounting of the switch member  30 ′ as well as the pawl  23 ′ and associated springs  26 ′ and threaded end caps  27 ′ are troublesome and time-consuming. The sector-like recessed area  28 ′ in the web results in an increase in the overall thickness of the wrench, which limits application of the wrench in limited spaces. The torque-bearing capacity was found poor, as only a portion of the pawl  23 ′ meshed with the drive member  22 ′ was supported by the inner wall of the V-shape transverse through-hole  25 ′, as shown in FIG.  20 . 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a reversible ratchet type wrench comprises: 
     a handle; 
     a head extended from the handle and including a hole, the handle comprising a transverse receptacle communicated with the hole, the transverse receptacle comprising an inner longitudinal wall that faces the hole of the head, the handle further comprising a cavity that communicates with the transverse receptacle; 
     a drive member rotatably mounted in the hole of the head, the drive member including a plurality of teeth formed on an outer periphery thereof; 
     two pawls mounted in the transverse receptacle in a spaced manner and each including a first side with a plurality of teeth for releasably engaging with the teeth of the drive member and a second side abutting against the inner longitudinal wall of the transverse receptacle; 
     a switch member including a turn-piece for manual operation, the switch member being rotatably mounted in the cavity of the handle and comprising an actuating portion for selectively moving one of the pawls to a position not engaging with the teeth of the drive member, the switch member further comprising two support portions for selectively supporting a portion of the other pawl that disengages from the inner longitudinal wall of the transverse receptacle, thereby supporting the other pawl that engages with the teeth of the drive member; and 
     means for biasing the teeth of the pawls to engage with the teeth of the drive member, respectively. 
     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 
     FIG. 1 is a perspective view of an end portion of a first embodiment of a wrench in accordance with the present invention. 
     FIG. 2 is an exploded perspective view of the wrench in FIG.  1 . 
     FIG. 3 is a sectional view of the wrench in FIG.  1 . 
     FIG. 4 is a sectional view taken along line  4 — 4  in FIG. 3, wherein the wrench is in a status allowing clockwise ratcheting. 
     FIG. 5 is a view similar to FIG. 4, wherein the wrench is in a status allowing counterclockwise ratcheting. 
     FIG. 6 is a sectional view illustrating a modified embodiment of the gear wheel of the wrench in FIG.  1 . 
     FIG. 7 is an exploded perspective view of another modified embodiment of the wrench in accordance with the present invention. 
     FIG. 8 is a sectional view, taken along line  8 — 8  in FIG. 10, of the wrench in FIG. 7, wherein the wrench is in a status allowing clockwise ratcheting. 
     FIG. 9 is a view similar to FIG. 8, wherein the wrench is in a status allowing counterclockwise ratcheting. 
     FIG. 10 is a sectional view of the wrench in FIG.  7 . 
     FIG. 11 is an exploded perspective view of a further modified embodiment of the wrench in accordance with the present invention. 
     FIG. 12 is an exploded perspective view of still another modified embodiment of the wrench in accordance with the present invention. 
     FIG. 13 is an exploded perspective view of a conventional ratchet type wrench. 
     FIG. 14 is a sectional view of a head portion of the conventional ratchet type wrench in FIG.  13 . 
     FIG. 15 is a top view, partly sectioned, of a portion of a conventional wrench. 
     FIG. 16 is an exploded view of a portion of another conventional wrench. 
     FIG. 17 is a top view, partly sectioned, of the portion of the conventional wrench in FIG.  16 . 
     FIG. 18 is a view similar to FIG. 17, wherein the switch member of the wrench is in a position for ratcheting in a reverse direction. 
     FIG. 19 is an exploded perspective view of a further conventional wrench. 
     FIG. 20 is a top view, partly sectioned, of a portion of the conventional wrench in FIG.  19 . 
     FIG. 21 is a side view, partly sectioned, of the portion of the conventional wrench in FIG.  19 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIGS. 1 through 12 and initially to FIGS. 1 through 4, a ratchet type wrench  10  in accordance with the present invention generally includes a handle  12  and a head  11  having a hole  13 . An inner periphery defining the hole  13  of the head  11  includes an annular groove  132  in an upper portion thereof and an annular ledge  131  on a lower portion thereof. A transverse receptacle  14  extending transversely to the inner periphery of the hole  13  (FIG. 4) is defined in the handle  12  and includes an intermediate portion communicated with the hole  13 . The transverse receptacle  14  extends from one lateral side  19   b  of the handle  12  toward the other lateral side  19   a  of the handle  12  but spaced from the other lateral side  19   a , thereby defining an opening  141  in the lateral side  19   b . The transverse receptacle  14  includes an inner wall  142  (FIG. 4) that extends longitudinally of the transverse receptacle  14  and that faces the hole  13 , which will be described later. A cavity  15  is defined in the handle  12  and communicated with the transverse receptacle  14 . The cavity  15  communicated with the transverse receptacle  14  has a first end communicated with outside and a second end located in the handle  12 , thereby leaving a bridge  16  on the handle  12  for connecting with the head  11 . Namely, the cavity  15  extends from an upper side of the handle  12  toward a bottom side of the handle  12  but spaced from the bottom side of the handle  12 , best shown in FIG.  3 . The cavity  15  is preferably cylindrical. The bridge  16  increases the strength of the head  11  and the handle  12 , thereby providing a higher torque-bearing capacity. 
     A drive member (in the form of a gear wheel  20  in this embodiment) is mounted in the head  11  and includes an inner periphery  24  for driving a fastener (not shown) and an outer periphery  25 . The outer periphery  25  includes a recessed upper end portion  22 , a recessed lower end portion  23 , and a middle portion with a plurality of recessed teeth  21 . A retainer  60 , preferably a ring, is mounted around the recessed upper end portion  22  and includes an annular groove  61 . A C-clip  30  is engaged in the annular groove  61  of the retainer  60  and in the annular groove  132  of the hole  13 , thereby rotatably retaining the gear wheel  20  in the head  11  of the wrench  10 , best shown in FIG.  3 . As illustrated in FIG. 3, the recessed lower end portion  23  abuts against and is thus supported by the annular ledge  131  of the head  11 . 
     Two pawls  41  and  42  are mounted in the transverse receptacle  14  in a spaced manner and each include ratchet teeth  411 ,  421  on a side thereof for engaging with teeth  21  of the gear wheel  20 . The ratchet teeth  411 ,  421  are preferably arranged along a concave face so as to be in intimate contact with the teeth  21  of the gear wheel  20 . The other side  412 ,  422  of each pawl  41 ,  42  presses against the inner longitudinal wall  142 , best shown in FIG.  4 . The inner pawl  41  further includes an end  413  to which an end of an elastic element (e.g., a spring  43 ) is attached, the other end of the spring  43  being attached to an end wall defining the transverse receptacle  14 . The outer pawl  42  includes an outer end  423  to which an elastic element (e.g., a spring  44 ) is attached. An end cap  45  is securely mounted in the opening  141  of the transverse receptacle  14 , and the other end of the spring  44  is attached to an inner side of the end cap  45  such as being received in bore  451  formed in end cap  45 . Thus, the respective pawl  41 ,  42  is biased by the respective spring  43 ,  44  toward the gear wheel  20 . 
     Still referring to FIGS. 1 through 3, a switch member  50  is rotatably mounted in the cavity  15 . In this embodiment, the switch member  50  includes a turn-piece  51  on a top thereof, the turn-piece  51  being preferably located outside the cavity  15  for manual operation. The switch member  50  comprises an actuating portion  54  for selective engagement with an end  414 ,  424  of the respective pawl  41 ,  42 . The switch member  50  further comprises two support portions  52  and  53  each for supporting a portion of the second side  412 ,  422  of the respective pawl  41 ,  42 , best shown in FIG.  4 . It is noted that the switch member  50  includes a bottom  56  that is located below the pawls  41  and  42  after assembly, thereby preventing disengagement of the switch member  50 . 
     The ratchet type wrench in FIG. 4 is in a status allowing clockwise ratcheting (free rotation in counterclockwise direction), in which the actuating portion  54  of the switch member  50  presses against the end  424  of the pawl  42 , thereby disengaging the pawl  42  from the gear wheel  20 . The other pawl  41  is biased by the spring  43  toward the gear wheel  20 . The teeth  411  of the pawl  41  are in intimate contact with the gear wheel  20  and the leading portion (not labeled) of the second side  412  of the pawl  41  that leaves the inner longitudinal wall  142  of the transverse receptacle  14  is supported by the support portion  52  of the switch member  50 . A higher torque is provided, as the drive member  20  is firmly engaged with and in intimate contact with the teeth  411  of the pawl  41 . In addition, the force transmitted to the pawl  41  from the drive member  20  is distributed to the inner longitudinal wall  142  of the transverse receptacle  14  having a relatively large area. As a result, the wrench in accordance with the present invention may bear higher torque. 
     When a change in the ratcheting direction is required, the user may switch the turn-piece  51  and thus move the actuating portion  54  of the switch member  50  to press against the pawl  41 . Thus, the ratchet-type wrench is in a status allowing counterclockwise ratcheting and free rotation in the clockwise direction. As illustrated in FIG. 5, the actuating portion  54  of the switch member  50  presses against the end  414  of the pawl  41 , thereby disengaging the pawl  41  from the gear wheel  20 . The pawl  42  is biased by the spring  44  toward the gear wheel  20 . The teeth  421  of the pawl  42  are in intimate contact with the gear wheel  20  and the leading portion (not labeled) of the second side  422  of the pawl  42  that leaves the inner longitudinal wall  142  of the transverse receptacle  14  is supported by the support portion  53  of the switch member  50 . A higher torque is provided, as the drive member  20  is firmly engaged with and in intimate contact with the teeth  421  of the pawl  42 . In addition, the force transmitted to the pawl  42  from the drive member  20  is distributed to the inner longitudinal wall  142  of the transverse receptacle  14  having a relatively large area. As a result, the wrench in accordance with the present invention may bear higher torque. 
     FIG. 6 is a modified embodiment of the wrench in accordance with the present invention, wherein the gear wheel  20  in the above embodiment is replaced by a drive member of the type having a drive column  26 . 
     FIGS. 7 through 10 illustrates another modified embodiment in accordance with the present invention, wherein the cavity  15  includes a first positioning recess  151  and a second positioning recess  152  that can be processed from the upper side of the handle  12  by means of a conventional drilling or milling machine, which is very easy to manufacture. In addition, the switch member  50  comprises a receptacle  55  for receiving a positioning means  200  comprising a spring  201  and a ball  202 . The ball  202  is biased by the spring  201  to be selectively engaged in a respective positioning recess  151 ,  152  according to the ratcheting direction of the wrench. More particularly, the switch member  50  can be reliably retained in place during ratcheting operation by means of provision of the positioning recesses  151  and  152  and the positioning means  200 . 
     FIG. 11 is an exploded perspective of a further modified embodiment that is modified from the embodiment shown in FIGS. 7 through 10. In this embodiment, the ball is replaced by a pin  204  having a dome  205 . FIG. 12 is an exploded perspective of still another modified embodiment that is modified from the embodiment shown in FIGS. 7 through 10. In this embodiment, the ball is replaced by a sheet-like positioning member  203  having an arcuate end  206 . 
     According to the above description, it is appreciated that the torque-bearing capacity of the wrench in accordance with the present invention is greater than conventional designs. In addition, the wrench in accordance with the present invention can be assembled easily. It is noted that the switch member  50  can be assembled without the need of any C-clip or other fasteners. Disengagement of the switch member  50  is prevented by provision of the bottom  56  of the switch member  50  that is located below the pawls  41  and  42 . Further, the positioning notches  151  and  152  of the cavity  15  can be formed by means of punching along a vertical direction and then trimming the burs, which is much simpler than formation of an angled-cavity in conventional designs. 
     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.