Patent Publication Number: US-4546677-A

Title: Slip-on screwdriver ratchet

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     Ratchet screwdrivers, or other ratcheting mechanisms for fastener drivers such as screwdrivers, nut drivers, and the like, typically are constructed so that the ratcheting mechanism is built directly into the screwdriver, so that the two are sold together, or so that a specialized screwdriver is ncessary in order to cooperate with the ratching assembly. 
     According to one aspect of the present invention, a drive assembly for a screwdriver is provided that is extremely versatile. The drive assembly according to the invention may be used with a wide variety of conventional screwdrivers that are already on the market. This allows the individual who already has sets of screwdrivers, nut drivers, and the like to merely purchase the driver assembly, and to utilize the driver assembly with a wide variety of such conventional screwdrivers, nut drivers, or the like. The driving assembly according to the invention simply slips over a conventional existing handle of a screwdriver, and thereby quickly and easily changes the conventional screwdriver into a ratcheting screwdriver. 
     According to another aspect of the present invention, a particular ratchet means is provided, the ratchet means particularly adapted for use with a drive assembly according to the invention. The ratchet means includes a single, toothed ratchet wheel rotatable about an axis of rotation, and a plurality of pawls, each pawl having two toothed lobes. All the pawls are mounted about a common axis of rotation, which is generally parallel to the axis of rotation of the ratchet wheel. A selector knob, with a spring extending therefrom and engaging the pawls, determines which lobe of each pawl is to be biased into operative association with the toothed ratchet wheel, thereby to select a direction of ratcheting rotation. The teeth of adjacent pawls are displaced with respect to each other so as to minimize the amount of rotation between stops of the ratchet wheel for a given tooth spacing of the wheel. 
     It is the primary object of the present invention to provide for the simple, effective, and versatile ratcheting of a screwdriver or the like. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of an exemplary drive assembly according to the present invention, for use with a conventional screwdriver or the like; 
     FIG. 2 is a bottom view of the assembly of FIG. 1; 
     FIG. 3 is a top view of the assembly of FIG. 1 with the top cover removed; 
     FIG. 4 is a longitudinal cross-sectional view of the assembly of FIG. 1, with some parts shown in elevation; 
     FIG. 5 is a side view of an exemplary conventional screwdriver with which the assembly of FIGS. 1 through 4 is utilizable; 
     FIG. 6 is a top plan view of the handle of the screwdriver of FIG. 5; 
     FIG. 7 is a side view of the handle of another type of conventional screwdriver; 
     FIG. 8 is a top plan view of the handle of the screwdriver of FIG. 7; 
     FIG. 9 is an exploded view of interior components of the drive assembly of FIG. 1; 
     FIG. 10 is a side view of the socket adaptor and socket of FIG. 9 shown in an alternative position thereof; 
     FIG. 11 is a side view of another embodiment of a drive assembly according to the invention shown in operative association with the handle of a nut driver; and 
     FIG. 12 is a bottom view of the drive assembly of FIG. 11. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An exemplary drive assembly according to the present invention is shown generally by reference numeral 10 in FIGS. 1 through 4. The assembly 10 includes an outer housing 12, an insert 14 (see FIGS. 4, 9, and 10) received within the housing 12, and ratchet means, shown generally by reference numeral 16 in FIGS. 3 and 4. The drive assembly 10 comprises means for ready removable operative disposition in operative association with the handle of a conventional fastener driver, such as a screwdriver or a nut driver. For instance the assembly 10 is utilizable with a conventional screwdriver 18 illustrated in FIGS. 5 and 6, and including a driver shank 19 integral with a handle 20. 
     The insert 14 is received within the outer housing 12, and is rotatable with respect to the housing 12 and is dimensioned and shaped to cooperate with the handle 20 so that there is no relative rotation between the insert 14 and handle 20 when the handle 20 cooperates with the insert 14. The ratchet means 16 acts between the housing 12 and the insert 14 for effecting rotation of the insert 14 and the housing 12 together in one direction of rotation, but not the other. 
     Preferably the insert 14 comprises a socket having an open end 22 thereof adapted to receive the handle 20. The interior of the socket 14 has surface manifestations for cooperating with surface manifestations on the handle 20 so that the two rotate together. Typically cooperating peak and valley surface manifestations are provided in the socket and on the handle. For instance see the peaks 24 and valleys 25 for the socket 14 as illustrated in FIGS. 2 and 4, and the corresponding valleys 24&#39; and peaks 25&#39; of the handle 20. A particularly desirable configuration for the socket interior is generally the form of a Swiss Cross in cross-section, since many, many conventional screwdrivers on the market have a Swiss Cross configuration, as can be seen most clearly in FIG. 6. Note that the Swiss Cross configuration of the socket 14 allows it to effectively cooperate with screwdriver handles 20 having a wide variety of diameters, as exemplied by the dotted line circle segments in FIG. 6. 
     For enhanced versatility, preferably the insert 14 includes, in addition to the open end 22 thereof, a second, closed end 27 (see FIGS. 4, 9, and 10) opposite the open end 22. The closed end 27 has--extending outwardly therefrom, concentric with the open end 22 and generally along the dimension of elongation A (see FIGS. 9 and 10) of the insert 14--a drive projection 28. The drive projection 28 has a polygonal cross-section (e.g. a square cross-section--see FIG. 3), and is adapted to cooperate with a wide variety of conventional fastener drivers that the open socket end 22 of the insert does not cooperate with. For instance the drive projection 28 may cooperate with the handle 30 (see FIGS. 7 and 8) of another conventional screwdriver or nut driver, the handle 30 having means defining a polygon-cross-section opening 31 in the end thereof. The drive projection 28 fits in the opening 31 to effect driving of the handle 30. Of course the handle 30 can be associated with any conventional fastener driver, nut or bolt receiving socket, or the like. 
     In order to faciliate changeover of the insert 14 from a first position thereof (FIGS. 4 and 9) wherein the open end 22 faces outwardly from the bottom of the housing 12, to a second position wherein the drive projection 28 extends outwardly from the bottom of the housing 12, the locking lever means 33 and the socket adaptor 34 are provided. One or more grooves 35 (see FIGS. 4, 9, and 10) are provided in a circumferentially continous manner around the exterior surface of the cylindrical insert 14, each groove adapted for cooperation with the locking lever means comprising a locking lever 36 pivoted about a pivot pin 37 with a coil spring 38 or the like spring biasing a locking projection 39 of the lever 36 into operative association with the groove 35. The locking lever means 33 allows relative rotation between the insert 14 and the housing 12 but does not allow removal of the insert 14 from the housing 12 unless the lever 36 is pivoted in a counter-clockwise direction (in FIG. 4) about the pivot pin 37 so that the locking projection 39 is not within the groove 35. 
     The socket adaptor 34 provides cooperation between the insert 14 and the ratchet means 16. The socket adaptor 34 has two different surface manifestations associated therewith for cooperation with the insert 14 so as to provide connection of the insert 14 to the ratchet means 16 irrespective of which of the two positions (the FIG. 9 or the FIG. 10 position) in which the insert is disposed. As seen most clearly in FIGS. 3, 4, and 9, the first surface manifestation of the adaptor 34 preferably comprises a concentric bore 41 which has substantially the same cross-sectional shape and dimensions as the drive projection 28. The second surface manifestation of the socket adaptor 34 preferably comprises the castellated edge 42 thereof which is most remote from the ratchet means 16, and is adapted to cooperate with a corresponding castellated edge 43 formed on the first, open, end of the insert 14. Cooperation between the castellated edges 42, 43 is illustrated in FIG. 10. 
     The housing 12 preferably has an out-of-round configuration, which is adapted to facilitate grasping by a human hand, and maximum torque application. The shape thereof is clearly visible from FIGS. 1 through 3. In addition to having a central bore adapted to receive the insert 14 from the socket adaptor 34, an open top portion (see FIGS. 3 and 4) of the housing is also provided for receipt of the ratchet means 16. Preferably a removable cover 45 covers the open top of the housing 12. 
     A wide variety of ratchet means 16 may be utilized with the assembly 10. For instance conventional slanted toothed wheels and cooperating pawls (such as shown in U.S. Pat. No. 4,285,375), or conventional roller ratchets, may be provided. One particularly suitable ratchet assembly for use according to the invention is illustrated in FIGS. 3, 4, and 9. 
     The illustrated ratchet assembly 16 comprises a conventional straight-toothed ratchet wheel 50, made of hard plastic, or other suitable material, and mounted for rotation about an axis B--B, concentric with the insert 14 and adaptor 34. The adaptor 34 is received within an interior bore 51 of the ratchet wheel 50, and suitable means are provided for holding the adaptor 34 and wheel 50 for rotation together. Such means may take the form of a pin 52 (see FIG. 9) passing through aligned openings 53, 54 in the wheel 50 and adaptor 34, respectively. Alternatively, the bore 51 and the exterior surface of the adaptor 34 could both be out-of-round (e.g. square). 
     The ratchet means 16, as illustrated in FIGS. 3 and 4, also preferably comprises pawl means, preferably a plurality of two-lobed pawls 56, 57. The pawls 56, 57 are mounted for rotation about a common axis of rotation, defined by pivot pin 59 which is generally parallel to the axis B--B. The lobes 60, 61 of each of the pawls 56, 57 has teeth 62, 63, respectively (see FIG. 3) formed thereon for cooperation with the teeth of the wheel 50. The teeth 62, 63 are shaped and dimensioned, and/or the pawls 56, 57 are mounted in a particular relationship with respect to the wheel 50, to allow a ratcheting action. 
     The direction of ratcheting rotation will be determined by which of the lobes 60, 61 of the pawls 56, etc., is in operative engagement with the wheel 50. Selector means are desirably provided for selecting whether the lobe 60 of each pawl is in engagement with the wheel 50, or the the lobe 61, to thereby determine the direction of ratcheting rotation. The selector means, most clearly illustrated in FIGS. 1 and 4, preferably comprises a selector knob 65 mounted for sliding movement within a groove 66 formed in the side of the housing 12, with a spring means, such as a U-shaped spring steel leaf spring 67, extending therefrom and into biasing engagement with each of the pawls 56, 57. The juxtaposition of the spring 67 with respect to the pawls 56, 57 is seen in FIG. 4. By reciprocating the knob 65 in the dimension C, the engagement of the spring 67 on each of the pawls--e.g. pawl 56--with respect to the pivot pin 59 will change, so that the lobe 60 will be biased into operative engagement with the wheel 50 in one position (as seen in FIG. 3), and the lobe 61 biased into engagement in the other position. 
     The teeth 62, 63 of the adjacent pawls 56, 57 are offset slightly with respect to each other around the circumference of the wheel 50, and the pawls 56, 57 are spaced from each other in a dimension parallel to the axis B--B. The slight off-set of the teeth 62, 63 of adjacent pawls 56, 57 reduces (i.e. minimizes) the amount of rotation between stops of the wheel 50. Such an arrangement is more desirable than providing smaller teeth and/or teeth spacings for the ratchet wheel 50. Such pawl teeth offset is schematically illustrated in FIG. 4 wherein the lobes 60, 60&#39; of the adjacent pawls 56, 57 have slightly different lengths. 
     In FIGS. 11 and 12, another embodiment of the drive assembly according to the present invention is illustrated. This drive assembly is generally referenced by the reference numeral 110, and includes a housing 112 and an interior socket 114. In this embodiment the socket 114 is not nearly as elongated in the dimension A as that in the FIGS. 1 through 4, 9, and 10 embodiment. Ratchet means are also disposed between the socket 114 and the housing 112 in the FIGS. 11 and 12 embodiment, but such ratchet means are conventional and not illustrated. 
     The housing 112 of the drive assembly 110 includes a first portion 70 in the shape of a truncated cone, and includes a second portion 71, most remote from the open end 122 of the socket 114, that is substantially cylindrical. The diameter of the cylindrical portion 71 is much greater than the largest cross-sectional dimension of the handle 120 of a conventional nut driver, or the like, adapted to cooperate therewith, and is dimensioned so as to substantially fill the palm of a human hand. This allows the amount of torque to be applied by the device 110 to the tool 118 to be increased. 
     In a typical manner of utilization of the embodiment of FIGS. 1 through 4, 9, and 10, the insert 14 is received within the housing 12 so that the open end 22 thereof faces outwardly of the housing, and with the locking means 33 holding the insert 14 in place in the housing 12. The operator then merely passes the insert 14 over the handle 20 of a screwdriver, the cooperating surface manifestations 24, 25 of the interior of the insert 14 and the surface manifestations 24&#39;, 25&#39; of the handle 20 insuring that rotation of the insert 14 will be translated into rotation of the handle 20. Then the operator selects the desired direction of ratcheting rotation by moving the selector knob 65 to one of two positions, the operator grasps the housing 12, and starts rotating. Rotation of the housing 12 in one direction (e.g. clockwise in FIG. 3) causes the pawls 56, 57 to engage the ratchet wheel 50 so that the ratchet wheel 50, adaptor 34, insert 14, and handle 20 all rotate in that direction, while rotation of the housing 12 in the opposite direction (e.g. counter-clockwise in FIG. 3) allows the pawls 56, 57 to move out of engagement with the teeth of the wheel 50 so that relative rotation between the housing 12, wheel 50, and socket adaptor 34 on the one hand, and the insert 14 and handle 20 on the other hand, takes place. 
     When it is desired to use the assembly 10 with a driver handle such as illustrated in FIGS. 7 and 8, the operator merely pivots the lever 36 against the bias of spring 38 to remove the locking projection 39 from the groove 35, pulls the insert 14 out of the housing 12, turns the insert 180° about an axis perpendicular to the dimension of elongation A thereof, and reinserts the insert 14 into the housing 12. In this position, the castellated edge 43 of the insert 14 (see FIG. 10) moves into engagement with the castellated edge 42 of the adaptor 34, and the locking lever 39 automatically moves into engagement with a groove 35, with the drive projection 28 extending outwardly from the bottom of the housing 12. The drive projection 28 is then inserted in the opening 31 in the handle 30, and ratcheting action is repeated as described above. 
     It will thus be seen that according to the present invention the simple, effective, and versatile ratcheting of conventional screwdrivers or the like may be provided. While the invention has been herein shown and described in what is presently conceived to be the most practical and preferred embodiment thereof, it will be apparent to those of ordinary skill in the art that many modifications may be made thereof within the scope of the invention, which scope is to be accorded the broadest interpretation of the appended claims so as to encompass all equivalent structures and devices.