Patent Publication Number: US-6209423-B1

Title: Ratchet spanner

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a ratchet spanner, more particularly to a ratchet spanner which includes components that can be easily assembled during the manufacturing process thereof and which requires little operating space to operate the same. 
     2. Description of the Related Art 
     Referring to FIGS. 1 and 2, a conventional ratchet spanner is shown to include a spanner body  1  and a ratchet mechanism. The spanner body  1  has an annular head portion  101  defining a ratchet accommodating chamber  102  with a lower end opening. The ratchet mechanism includes a ratchet wheel  105  disposed rotatably in a front section  103  of the chamber  102  via the lower end opening such that a tool mounting shank  105 ″ of the ratchet wheel  105  projects outwardly of the chamber  102 . Two spring-biased pawls  107  and a pawl actuator  106  are disposed in a rear section  104  of the chamber  102  and are operably connected to the ratchet wheel  105 . The pawl actuator  106  can be manually operated in either one of two directions in order to engage a selected one of the pawls  107  with the ratchet wheel  105  such that the conventional ratchet spanner is turnable in only a single direction when in operation. 
     Some of the drawbacks of the aforementioned conventional ratchet spanner are as follows: 
     It is somewhat difficult to assemble the components of the aforesaid ratchet spanner. During assembly, after the ratchet wheel  105 , the spring-biased pawls  107  and the pawl actuator  106  are mounted in the chamber  102 , a cover shield  109  is mounted on the spanner body  1  by the use of screws  109 ′ to prevent downward removal of the ratchet wheel  105  from the head portion  101  of the spanner body  1 . As such, a relatively long assembly time is incurred. 
     In addition, because the ratchet wheel  105  has a relatively small number of teeth  105 ′ with great pitches, in order to ensure engagement between a rectangular end  107 ′ of the pawls  107  and the teeth  105  ′ of the ratchet wheel  105 , a large amount of operating space is needed for turning of the spanner body  1 . 
     Referring to FIGS. 3 and 4, another conventional ratchet spanner is shown to include a spanner body  2  and a ratchet mechanism. The spanner body  2  includes an annular head portion  201  which has a peripheral wall  201 A with top and bottom ends and an opening  202  formed through the top and bottom ends, and top and bottom flanges that extend radially and inwardly from the top and bottom ends. The ratchet mechanism includes a ratchet wheel  205  that is disposed rotatably within the opening  202  in the head portion  201  and that defines a tool accommodating cavity at the central portion thereof, a pawl unit  206  disposed within the opening  202 , and a spring unit  207  that is disposed within a retention bore  204  formed in the peripheral wall  201 A and that biases the pawl unit  206  to engage teeth  205  ′ of the ratchet wheel  205 . 
     Because the ratchet wheel  205  is provided with densely located fine profile teeth  205  ′, only a small amount of operating space is required to operate the aforesaid conventional spanner. However, during the manufacture of the ratchet wheel  205 , high precision and great skill are needed to produce such type of fine profile teeth  205 ′. A high manufacturing cost is thus incurred. 
     During mass production, a curved recess  203  is firstly formed in the peripheral wall  201 A. The retention bore  204  is then formed by a milling unit and a drilling unit. Since only a small-diameter cutting tool can be used in order to form the retention bore  204  with a relative depth, the cutting tool easily breaks under high speeds of rotation, thereby inconveniencing the operator. 
     SUMMARY OF THE INVENTION 
     Therefore, the object of this invention is to provide a ratchet spanner which includes components that are easily manufactured and assembled during the manufacturing process and which requires a relatively small amount of space to operate the same. 
     Accordingly, a ratchet spanner of the present invention includes a spanner body, a stepped insert member, a vertical cylindrical ratchet wheel, a spring-biased pawl assembly, and a control element. The spanner body has a head portion and a handle, which has an end connected fixedly to the head portion. The head portion has a peripheral wall with a top end and a bottom end, a top flange that extends integrally and inwardly from the top end of the peripheral wall, and a bottom flange that extends integrally and inwardly from the bottom end of the peripheral wall. The top flange defines a top opening therein, and has a curved and slotted inner peripheral surface with an open-ended slot that extends circumferentially therealong. The bottom flange has a circular inner peripheral surface, which is formed with an inward flange that extends integrally, radially and inwardly from a bottom end of the circular inner peripheral surface and that defines a bottom opening therein. The insert member is inserted into the head portion of the spanner body between the top and bottom flanges. The insert member has a lower portion with a top surface, an upper portion that extends integrally and upwardly from the top surface of the lower portion, and a curved shoulder defined between the upper and lower portions. The upper portion of the insert member has a curved side surface, which is formed with an open-ended slot that extends circumferentially therealong and that cooperates with the open-ended slot in the head portion to form an annular slot unit. The upper portion of the insert member extends into the top opening in the head portion of the spanner body. The curved shoulder of the insert member abuts against the top flange of the head portion of the spanner body for preventing upward removal of the insert member from the head portion. The lower portion of the insert member has a side surface with two chamber units and abuts against the bottom flange for preventing downward removal of the insert member from the head portion of the spanner body. The ratchet wheel is disposed rotatably within the head portion of the spanner body. The ratchet wheel has a diameter-reduced bottom end that extends into the bottom opening in the head portion of the spanner body and that defines a circular shoulder, a toothed portion with a plurality of ratchet teeth, and a top end portion that is formed with an annular groove. The circular shoulder of the ratchet wheel abuts against the inward flange of the head portion of the spanner body for preventing downward removal of the ratchet wheel from the head portion of the spanner body. A C-shaped retaining ring is disposed in the head portion of the spanner body in such a manner that the ring engages the annular groove in the ratchet wheel, the open-ended slot in the head portion and the open-ended slot in the insert member for preventing removal of the ratchet wheel and the insert member from the head portion of the spanner body. The pawl assembly includes a first pawl unit and a second pawl unit, which are received respectively within the chamber units in the insert member and which are biased by a spring action to engage the toothed portion of the ratchet wheel. Engagement between the toothed portion of the ratchet wheel and the first pawl unit prevents rotation of the ratchet wheel within the head portion of the spanner body in a first direction. Engagement between the toothed portion of the ratchet wheel and the second pawl unit prevents rotation of the ratchet wheel within the head portion of the spanner body in a second direction that is opposite to the first direction. The control element is mounted operably on the insert member such that the control element presses selectively against one of the first and second pawl units against the spring action, thereby permitting rotation of the ratchet wheel within the head portion of the spanner body in a selected one of the first and second directions. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features and advantages of this invention will become more apparent in the following detailed description of the preferred embodiments of this invention, with reference to the accompanying drawings, in which: 
     FIG. 1 is a partly exploded perspective view of a conventional ratchet spanner; 
     FIG. 2 is a schematic top view of the conventional ratchet spanner, illustrating how a spring-biased pawl unit engages a ratchet wheel; 
     FIG. 3 shows a partly exploded fragmentary perspective view of another conventional ratchet spanner; 
     FIG. 4 is a fragmentary schematic view of the conventional ratchet spanner shown in FIG. 3, illustrating how a spring-biased pawl unit engages a ratchet wheel; 
     FIG. 5 is an exploded perspective view of the preferred embodiment of a ratchet spanner of the present invention; 
     FIG. 6 is a partly sectional schematic side view of the preferred embodiment; 
     FIG. 7 is a partly sectional schematic top view of the preferred embodiment, illustrating how a plurality of spring-biased pawl units and a pawl control element are disposed in an end portion of a spanner body; 
     FIG. 8 is a partly sectional schematic top view of the preferred embodiment, illustrating a first state where a ratchet wheel is turnable relative to a spanner body in a first direction; 
     FIG. 9 is a partly sectional schematic top view of the preferred embodiment, illustrating a second state where the ratchet wheel is turnable relative to the spanner body in a second direction; 
     FIG. 10 is a partly sectional schematic side view of a modified preferred embodiment; and 
     FIG. 11 is a partly sectional schematic top view of yet another modified preferred embodiment, illustrating a state where the ratchet wheel is turnable relative to the spanner body in only one direction. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIGS.  5 , 6  and  7 , the preferred embodiment of a ratchet spanner of the present invention is shown to include a spanner body  10 , a stepped insert member  20 , a vertical cylindrical ratchet wheel  60 , a C-shaped retaining ring  70 , a spring-biased pawl assembly, and a pawl control element  50 . 
     As illustrated, the spanner body  10  has a head portion  12  and a handle  11 , which has an end connected fixedly to the head portion  12 . The head portion  12  has aperipheral wall  120  with a top end  121  and a bottom end  122 , a top flange  123  that extends integrally and inwardly from the top end  121  of the peripheral wall  120 , and a bottom flange  124  that extends integrally and inwardly from the bottom end  122  of the peripheral wall  120 . The top flange  123  defines a top opening  1211  therein, and has a curved and slotted inner peripheral surface  1212  with an open-ended slot  132  that extends circumferentially therealong. The bottom flange  124  has a circular inner peripheral surface  1240 , which is formed with an inward flange  1241  that extends integrally, radially and inwardly from a bottom end of the circular inner peripheral surface  1240  and that defines a bottom opening  1245  therein. 
     The insert member  20  is inserted into the head portion  12  of the spanner body  10  between the top and bottom flanges  123 ,  124 . The insert member  20  has a lower portion  21  with a top surface  210 , an upper portion  22  that extends integrally and upwardly from the top surface  210  of the lower portion  21 , and a curved shoulder  211  defined between the upper and lower portions  22 , 21 . The upper portion  22  has a curved side surface  220 , which is formed with an open-ended slot  24  that extends circumferentially therealong and that cooperates with the open-ended slot  132  in the head portion  12  of the spanner body  10  to form an annular slot unit. The upper portion  22  extends into the top opening  1211  in the head portion  12  of the spanner body  10 . Under such a condition, the curved shoulder  211  of the insert member  20  abuts against the top flange  123  of the head portion  12  of the spanner body  10  for preventing upward removal of the insert member  20  from the head portion  12  of the spanner body. The lower portion  21  further has a side surface  215  that is formed with two chamber units  23  and that abuts against the bottom flange  124  of the head portion  12  for preventing downward removal of the insert member  20  from the head portion  12  of the spanner body  10 . 
     The cylindrical ratchet wheel  60  is disposed rotatably within the head portion  12  of the spanner body  10 , and has a diameter-reduced bottom end  61  that extends into the bottom opening  1245  in the head portion  12  and that defines a circular shoulder  610 , a toothed portion  62  with a plurality of ratchet teeth, and a top end portion  64 . The top end portion  64  of the ratchet wheel  60  is formed with an annular groove  640 . The circular shoulder  610  of the ratchet wheel  60  abuts against the inward flange  1241  of the head portion  12  for preventing downward removal of the ratchet wheel  60  from the head portion  12  of the spanner body  10 . 
     The C-shaped retaining ring  70  is disposed in the head portion  12  in such a manner that the retaining ring  70  engages the annular groove  640  in the ratchet wheel  60 , the open-ended slot  132  in the head portion  12  of the spanner body  10 , and the open-ended slot  24  in the insert member  20  for preventing removal of the ratchet wheel  60  and the insert member  20  from the head portion  12  of the spanner body  10 . 
     The pawl assembly  30  includes a first pawl unit  301  and a second pawl unit  302 , which are received respectively within the chamber units  23  in the insert member  20  and which are biased by spring units  40  to engage the toothed portion of the ratchet wheel  60 . Under such a condition, engagement between the toothed portion of the ratchet wheel  60  and the first pawl unit  301  prevents rotation of the ratchet wheel  60  within the head portion  12  of the spanner body  10  in a first direction. Engagement between the toothed portion of the ratchet wheel  60  and the second pawl unit  302  prevents rotation of the ratchet wheel  60  within the head portion  12  of the spanner body  10  in a second direction opposite to the first direction. 
     The control element  50  is mounted operably on the insert member  20  and presses selectively against one of the first and second pawl units  301 ,  302  against the action of the spring units  40 . Under this state, the ratchet wheel  60  within the head portion  12  is permitted to rotate in a selected one of the first and second directions. 
     The insert member  20  is further formed with a slide slot unit  25  that extends across the chamber units  23  and which receives slidably the control element  50  therein. The control element  50  can slide into a selected one of the chamber units  23  in the insert member  20  so as to press against a corresponding one of the first and second pawl units  301 ,  302 . Under such a condition, the ratchet wheel  60  is permitted to rotate within the head portion  12  of the spanner body  10  in the selected direction. Preferably, the control element  50  includes a slide piece  51  formed with two spaced stop grooves  511  which selectively engage the stops  32  of one of the first and second pawl units  301 ,  302 . Under this condition, the stop teeth  33  of the other one of the first and second pawl units  301 ,  302  engage the toothed portion of the ratchet wheel  60 , as best shown in FIGS. 8 and 9, such that the ratchet wheel  60  is permitted to rotate in the selected direction. Referring to FIG. 7, when the control element  50  is moved in the chamber units  23  so as to be at an intermediate position of the slot unit  25 , the stops  32  of an adjacent pair of the first and second pawl units  301 ,  302  respectively engage the stop grooves  511  of the control element  5 . Under this condition, the ratchet wheel  60  is prevented from rotation such that the ratchet spanner of the present invention serves as a conventional spanner. 
     In the preferred embodiment, the bottom flange  124  of the head portion  12  is formed with a curved rod hole  15  therethrough. In order to facilitate manual actuation of the control element  50 , the latter is provided with an actuation rod  52  that extends integrally from the slide piece  51  and through the rod hole  15  in the bottom flange  124  for actuation by the fingers of the operator. Preferably, the chamber units  23  include four chambers  230 . The first pawl unit  301  includes two first pawl members that are received within two of the four chambers  230 . The second pawl unit  302  includes two second pawl members that are received within another two of the four chambers  230 . The chambers  230  are arranged in a row along the slide slot unit  25 . The insert member  20  further includes three partitions  231 , each of which is disposed between an adjacent pair of the chambers  230 . Each of the partitions  231  has a notch  233  that forms a portion of the slide slot unit  25 . Preferably, the ratchet wheel  60  has an end surface that is formed integrally with a post  63  of a rectangular cross-section such that a socket (not shown) for turning of a workpiece can be mounted thereon. 
     Referring to FIG. 11, a second preferred embodiment is shown to be is similar to the first preferred embodiment in structure, except that the ratchet wheel  60  ′ has an end surface formed with a hexagonal hole  65  ′ for receiving an operating tool or hexagonal head of a bolt therein (not shown). 
     Referring to FIG. 10, a third preferred embodiment is shown to be similar to the first preferred embodiment in structure, except that the ratchet wheel  60 ″ is annular-shaped, and has a splined inner cavity  65 ″ for receiving an operating tool (not shown) therein. A magnetic piece  66  ′ is mounted fixedly in an innermost wall of the cavity  65 ″ for attracting with the operating tool so as to prevent untimely removal of the same. 
     The advantages that result from the use of the aforesaid ratchet spanner of this invention are as follows: 
     Since the pawl members  30  are constantly biased by spring units  40  in a radial direction with respect to the ratchet wheel  60 , engagement of the pawl members with the ratchet wheel  60  is ensured. The fine profile teeth on the ratchet wheel  60  further ensure that only little space is required when operating the ratchet spanner of the present invention. 
     The top and bottom flanges  123 ,  124  in the head portion  12  of the spanner body  10 , and the ratchet accommodating bore between the top and bottom flanges  123 ,  124  can be formed by a large-diameter milling tool, which does not easily break during the machining process. 
     With this invention thus explained, it is apparent that numerous modifications and variations can be made without departing from the scope and spirit of this invention. It is therefore intended that the invention be limited only as indicated in the appended claims.