Abstract:
This invention relates to a fastener driving device including a variable ratio gear mechanism that enables the ratio of the rotation of the handle to the rotation of a driving bit extending from the handle to be varied to allow the bit to rotate at different speeds from the handle. The device includes a gear mechanism disposed within a housing for the device that includes a locking member and a biasing member. The biasing member urges the locking member into engagement with the gear mechanism to lock the gear mechanism in a configuration for a 1:1 gear ratio. A selector switch is secured to the device over the gear mechanism and is operable to move the locking member into and out of engagement with the planetary gears against the bias of the biasing member to provide an increased gear ratio for the gear mechanism when desired.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to a device for driving or removing fasteners from a substrate, such as a screwdriver, that includes a ratcheting mechanism to assist in driving the fastener. 
       BACKGROUND OF THE INVENTION 
       [0002]    In the past a variety of different types of devices have been developed to drive fasteners into a substrate for various purposes. The type of device most often utilized to drive the fastener is a screwdriver or similar device that translates the rotation of the screwdriver by the individual into rotation of the fastener to urge the fastener into the desired substrate. 
         [0003]    On many occasions, the particular location where the fastener need to be located or the type of substrate into which the fastener is to be driven creates a certain amount of difficulty in driving the fastener into the substrate. To provide some assistance in driving the fasteners in these more difficult situations, many of these devices are constructed with a ratcheting mechanism. The ratcheting mechanism allows the individual to restrict the rotation of the driver to a single direction, which eases the difficulty of driving the fastener. 
         [0004]    Nevertheless, the devices, whether including a ratcheting mechanism or not, produces only a one to one ratio between the rotation of the device by the individual and the corresponding rotation of the fastener. As a result, it normally takes a significant amount of time to completely drive the fastener into the substrate. 
         [0005]    In an attempt to increase the speed of driving a fastener into a substrate, certain prior art devices have been developed that can alter the ratio of the rotation of the handle of the device with respect to the driving bit of the device, to thereby increase the speed of driving the fastener into the substrate. One device of this type is disclosed in Murphy U.S. Pat. No. 6,899,653, which discloses a fastener with a gear assembly. In this device, the fastener includes a plate having a number of openings formed therein. The plate is connected to a sun gear which engages a number of planetary gears positioned between the sun gear and a ring gear disposed on the exterior of the device. When engaged with and allowed to rotate freely with the planetary gears and the ring gear, the sun gear rotates at a speed faster than the rotation of the handle, at a ratio of approximately four rotations of the sun gear for each revolution of the handle. Further because the driving bit for the device is fixed to the sun gear, the bit also rotates at the 4:1 ratio to drive the fastener engaged with the bit into the substrate at a speed greater than the rotation of the device handle by the individual. 
         [0006]    The device also includes a switch located on the exterior of the device, and that is slidably movable with respect to the device. The switch includes a pin that can be selectively engaged and disengaged with one of the openings in the plate to which the sun gear is attached. Thus, when the pin is engaged with the plate, the pin prevents the plate and the sun gear from rotating separately from one another, so that the sun gear, as well as the bit connected thereto, and the handle rotate in a 1:1 ratio. 
         [0007]    However, while providing a design that enables the device to be operated at different gear ratios to increase the speed of the driving bit as desired, the device requires a separate switching mechanism to transition the device between the different gear ratios. This requires a separate mechanism to be formed on the device and significantly complicates the construction and operation of the device. In addition, the switch mechanism relies solely on the frictional engagement of the pin with the plate to main the lock between the plate and the pin, such that the switch mechanism can be inadvertently disengaged in a relatively easy manner. 
         [0008]    Accordingly, the prior art does not satisfy the needs and solutions required for devices of this type, such that it is desirable to develop a fastener-driving device that provides a simple construction and mechanism for altering the speed of rotation of the driving shaft relative to the handle. 
       SUMMARY OF THE INVENTION 
       [0009]    It is one object of the present invention to provide a fastener driving device including a variable ratio gear mechanism that enables the ratio of the rotation of the handle to the rotation of a driving bit extending from the handle to be varied to allow the bit to rotate at different speeds from the handle. The device includes a gear mechanism disposed within a housing for the device that includes a sun gear attached to a shaft extending through the housing and to which a driving bit can be connected. A number of planetary gears are disposed around the sun gear and operably engage the sun gear and the shaft with a ring gear secured to the housing. The planetary gears are disposed on a cover that is connected to a handle for the device, such that the rotation of the handle causes the planetary gears to rotate relative to the sun gear. 
         [0010]    The cover also encloses a locking member and a biasing member between the cover and the handle. The biasing member urges the locking member into engagement with the sun gear to lock the sun gear and the planetary gears to one another. A selector switch is secured to the device over the gear mechanism and is operable to move the locking member into and out of engagement with the planetary gears against the bias of the biasing member. 
         [0011]    According to another object of the present invention, the selector switch is continually biased into engagement with the planetary gears by the biasing member to avoid any inadvertent disengagement of the switch and consequent alteration of the gear ratio at which the device is operating. 
         [0012]    Numerous additional objects, aspects and advantages of the present invention will be made apparent from the following detailed description taken together with the drawing figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The drawings illustrate the best mode of practicing the present invention. 
           [0014]    In the drawings: 
           [0015]      FIG. 1  is a side pan view of a first embodiment of the driving device constructed according to the present invention in a locked position; 
           [0016]      FIG. 2  is a cross-sectional view of the driving device of  FIG. 1 ; 
           [0017]      FIG. 3  is a cross-sectional view along line  3 - 3  of  FIG. 1 ; 
           [0018]      FIGS. 4A-4C  are isometric exploded views of the device of  FIG. 1 ; 
           [0019]      FIG. 5  is a partially broken away isometric view of the gear mechanism of the device of  FIG. 1 ; 
           [0020]      FIG. 6  is a side pan view of the driving device of  FIG. 1  in an unlocked position; 
           [0021]      FIG. 7  is a cross-sectional view of the driving device of  FIG. 6 ; 
           [0022]      FIG. 8  is a cross-sectional view of a second embodiment of the driving device constructed according to the present invention; and 
           [0023]      FIG. 9  is a partially broken away isometric view of the gear mechanism of the device of  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    With reference now to the drawing figures in which like reference numbers represent like features throughout the application, a tool or device constructed according to the present invention is indicated at  10  in  FIG. 1 . The device  10  includes a housing  12  having a first end  14  and a second end  16 . The shape of the housing  12  can be made to have any desired and ergonomic configuration, and can be made of any suitable material, with a material that is both impervious to fluids and able to be sterilized in any conventional manner being especially preferred. Additionally, the material forming the housing  12  can be selected from a material having the desired properties that can be molded around the other components used in the formation of the device  10 . 
         [0025]    Referring now to  FIGS. 1-4C , the housing  12  includes a central passage  18  extending therethrough that includes a first expanded section  20  at the first end  14  and a second expanded section  22  at the second end  16 . Within the first expanded section  20  is disposed a suitable ratcheting mechanism  24 , such as that disclosed in co-pending and co-owned U.S. patent application Ser. No. 12/241,696, the entirety of which is expressly incorporated by reference herein in its entirety. The ratcheting mechanism  24  is held in the first expanded section  20  in any suitable manner to maintain fluid-impervious and sterilizable construction of the device  10 . The mechanism  24  is also capable of releasably receiving and engaging a driving member (not shown) therein that is used to directly engage a fastener (not shown) to enable the device  10  to drive the fastener into the desired substrate (not shown). The ratcheting mechanism  24  is preferably operable to restrict the rotation of the driving member to one direction, or to hold the driving member stationary when the device  10  is in use. 
         [0026]    A shaft  26  is disposed within and extends through the central passage  18  between the expanded sections  20  and  22 . The shaft  26  is held within the passage  18  by a number of bearings  27  that allow the shaft  26  to rotate freely in the passage  18 . The shaft  26  is also operably connected at one end to the ratcheting mechanism  24 , such that the rotation of the shaft  26  is controlled by the operation of the ratcheting mechanism  24 . Opposite the ratcheting mechanism  24 , the shaft  26  is affixed to a handle  28  that can be grasped and turned by an individual in order to operate the device  10 . The handle  28  can have any desired shape and configuration to maintain the fluid-proof and sterilizable structure, but in a preferred embodiment is formed of an interior component  30  formed of a rigid material and an outer resilient cover  32 . The interior component  30  enables the handle  28  to accommodate the stresses utilized in the operation of the device  10 , while the cover  32  provides a softer feel to the handle  28  when in use. The interior component  30  is not affixed to the shaft  26  opposite the ratcheting mechanism  24 , such that the turning motion applied to the handle  28  is not directly transmitted to the shaft  26  to turn the shaft  26  along with the handle  28 , but is directed to a gear mechanism  34  operably connecting the handle  28  and the shaft  26 . 
         [0027]    Between the handle  28  and the housing  12  is disposed a gear mechanism  34  that is disposed within the second expanded section  22  of the passage  18 . The mechanism  34  includes a support member  36  that is engaged with the handle  28 . The support member  36  includes an outer end  38  including an inwardly extending recess  40 . The recess  40  has a rim  42  that has a diameter greater than the outer diameter of the handle  28 , such that the handle  28  can be engaged with the support member  36  within the recess  38 . Preferably there is a sealing member  44  disposed in the recess  38  to be engaged with the handle  28  to provide a fluid-tight engagement of the handle  28  with the support member  36 . 
         [0028]    The support member  36  also includes a projection  46  extending outwardly from the recess  38 . The projection  46  is inserted into the handle  28  to further affix the handle  28  the housing  12 . The projection  46  also includes a central opening  48  located concentrically within the projection  46  that extends completely through the projection  46  and the support member  36 . The opening  48  is additionally disposed in concentric alignment with the passage  18  in the housing  12 , and has a sufficient diameter to enable the shaft  26  to extend through the opening  48  in order to be engaged within the handle  28 . 
         [0029]    Opposite the projection  46 , the support member  36  includes a number of attachment members  50 . The attachment members  50  extend outwardly from the support member  36  and each include a blind bore  52  therein. The attachment members  50  are disposed around the opening  48 , and taper inwardly towards the opening  48 . Each attachment member  50  includes a pair of flat side walls  54 , and are separated from one another by a flat section  56  of the support member  38 , for a purpose to be described. 
         [0030]    Between the projection  46  and the attachment members  50 , the support member  36  includes a radially outwardly extending flange  58 . The flange  58  includes a pair of flat sides  60  disposed opposite one another. The flange  58  serves as an engagement point for a number of biasing members  62  that are positioned on the flange  58  around the attachment members  50 . The biasing members  62  can have any desired form, but are preferably Belleville springs  64 . The biasing members  64  are retained against the flange  58  by a cover  66  secured to the support member  36 . Preferably, the cover  66  is circular in shape and includes an axially extending wall  68  extending outwardly therefrom. Within the wall  68  are located a number of slots  70 . Each slot  70  is preferably spaced equidistant from the remaining slots  70  around the perimeter of the wall  68 , and includes a pair of notches  72  and  74  spaced from one another by a spacing section  76 . The notch  74  is formed with a depth greater than the depth of the notch  72 , for a purpose to be described. 
         [0031]    The cover  66  also includes a central aperture  77  and a number of apertures  78  therein that are aligned with the bores  52  in the respective attachment members  50 . The cover  66  is affixed to the attachment members  50  over the biasing members  64  by screws  80  inserted through the apertures  78  and into engagement within the bores  52  in the attachment members  50 . The screws  80  are preferably formed with an end portion  82  on which threads  84  are located for engagement within the bore  52 , a smooth shaft  86  extending away from the end portion  82 , and a head  88  used to engage the end portion  82  within the bore  52 . The smooth shaft  86  is present to enable a planetary gear  90  to be mounted to each screw  80 . The planetary gear  90  is formed of any suitable material with a first width W 1 , and includes a central opening  92  and a number of teeth  94  disposed around the periphery of the gear  90 . The central opening  92  is dimensioned to have a diameter larger than that of the shaft  86  for the screw  80 , such that the shaft  86  can be inserted through the opening  92 , preferably with sufficient space for a bearing  96  to be positioned between the shaft  86  and the gear  90  within the opening  92 . 
         [0032]    Around the planetary gears  90  is located an annulus or ring gear  98 . The ring gear  98  is affixed to the housing  12  around the second expanded section  22  at the second end  16  of the housing  12 . The ring gear  98  includes a number of bores  100  through which suitable fasteners  102  are inserted to engage the ring gear  98  around the periphery of the second expanded section  22 . Additionally, the ring gear  98  is formed to have a width W 1  corresponding to the width of the planetary gears  90 , such that the ring gear  98  and planetary gears  90  are essentially coplanar with one another. The ring gear  98  further includes a number of teeth  104  disposed along the inner periphery of the ring gear  98  that are engaged by the aligned teeth  94  disposed on each of the planetary gears  90 , such that rotation of the planetary gears  90  causes the rotation of the ring gear  98 , and vice versa. 
         [0033]    The planetary gears  90  are secured to the cover  66  opposite the support member  36 , such that the gears  90  do not interfere with the operation of the biasing members  64 , and around a space  104  formed in the center of the over  66 . The space  104  allows for the shaft  26  to extend therethrough, and has a diameter large enough to accommodate a sun gear  106  therein. The sun gear  106  is formed as a hollow sheath  108  disposed around the shaft  26  that includes a central part  110 , from which extend a number of teeth  112 , and a pair of end parts  114  that extend axially from each end of the central part  110 . The sheath  108  is affixed to the shaft  26 , such that the sheath  108  rotates in conjunction with the shaft  26 . Further, the end parts  114  each support a bearing  116  thereon that engages the interior of the passage  18  to hold the sun gear  106  securely within the device  10 , while also allowing the gear  106  and shaft  26  to rotate freely therein. Also, the teeth  112  on the central part  110  contact and engage the teeth  94  on the planetary gears  90 , such that rotation of the sun gear  106  will cause consequent rotation of the planetary gears  90 , or vice versa. 
         [0034]    Additionally, the central part  102  has a second width W 2 , which is greater than the width W 1  of the planetary gears  90  and the ring gear  98 , such that the teeth  112  on the central part  110  axially extend beyond the teeth  94  on the planetary gears  90  in both axial directions. The portion of the teeth  112  that extend through the space  104  in the center of the cover  66  can be selectively contacted by a switch  118  to control the gear ratio achieved by the sun gear  106 , planetary gears  90  and ring gear  98 . 
         [0035]    The switch  118  includes a ring  120  slidably mounted to the exterior of the support member  36 . The ring  120  includes an enlarged section  122 , positioned adjacent the handle  28 , and a reduced section  124 , disposed around the wall  68  of the cover  66  and the ring gear  98 , that are joined to or integrally formed with one another to form the ring  120 . The enlarged section  122  includes a radially inwardly extending rim  126  that is slidably positioned around the support member  36  between the rim  42  and the flange  58  to operably connect the ring  122  to the support member  36 . 
         [0036]    Looking now at  FIGS. 2 ,  4 B,  4 C, and  5 - 7 , opposite the rim  126 , the reduced section  124  of the ring  120  includes a number of openings  128  extending radially therethrough. The openings  128  receive suitable fasteners  130  therein which operate to connect the reduced section  124  of the ring  120  to a locking member  132 . The locking member  132  is formed of any suitable, and preferably rigid material, and is shaped to have a fan blade-like shape, with a number of, e.g., preferably three, sections  134  extending radially outwardly from a central hub  136 . Each of the sections  134  is dimensioned to be positionable within the flat sections  56  of the support member  36  formed between the attachment members  50 , and preferably have an area less than the area of the flat sections  56  to allow some movement of the sections  134  with respect to the flat sections  56 . The sections  134  also each include a bore  138  at their outer ends within which the fastener  130  is inserted to engage the ring  120  with the locking member  132 . In one embodiment the bore  138  is disposed in an off-center position within the section  134 . Each of the fasteners  130  is inserted through a slot  70  in the wall  68 , which enables the fastener  130  to function as a stop for the movement of the locking member  132  with respect to the wall  68  and the cover  66 . 
         [0037]    The locking member  132  is also continuously engaged by the biasing members  64 , such that the biasing members  64  urge the locking member  132  away from the support member  36  and towards the cover  66 . Also, due to the positioning of the fasteners  130  within the slots  70 , the biasing members  64  press the fasteners  130  against the inner end of one or the notches  72  or  74  formed in the slot  70 , to maintain the fasteners  130 , and consequently the locking member  132 , at the particular location within the slot  70 . 
         [0038]    Looking now at  FIGS. 2 ,  3  and  7 , the hub  136  of the locking member  132  also defines an opening  140  therein through which the shaft  26  can extend. The opening  140  also includes a number of teeth  142  disposed along the periphery of the opening  140  that are selectively engageable with the teeth  112  on the sun gear  106 . When the fasteners  130  are disposed in the deeper notch  74  ( FIG. 2 ), the teeth  142  in the opening  140  are positioned in engagement with the teeth  122  on the sun gear  106 . In this position, due to the engagement of handle  28  with the shaft  26  via the support member  36 , cover  66  and the locking member  132 , when rotating the handle  28  while grasping the housing  12 , the rotation of the shaft  26  is in a 1:1 ratio with the rotation of the handle  28 . Conversely, when the fasteners  130  are disposed within the notch  72  in each slot  70  ( FIG. 7 ), the opening  140  and teeth  142  are spaced from the teeth  112  on the sun gear  106 . Therefore, when the handle  28  is rotated to turn the shaft  26  while holding the housing  12  stationary, the rotation of the handle  28  is transmitted through the support member  36  to the cover  66 , which in turn rotates the planetary gears  90  due to their movement along the ring gear  98 . The rotation of the planetary gears  90  it directly transmitted to the sun gear  106 , which provides 2:1 gear ratio to rotate the shaft two revolutions for every single revolution of the handle  28 . 
         [0039]    In either position, the switch  118  maintained in the selected position during operation of the device  10  due to the force exerted by the biasing members  64  on the locking member  132  and the depth of the notches  72  and  74 , which keeps the fasteners  130  disposed within the selected notch  72  or  74 . When it I desired to change the gear ratio for the device  10 , the switch  118  is grasped and urged towards the handle  28  against the bias of the biasing members  64 . Once the fasteners  130  have been moved out of the notch  72  or  74  in which they were located, the switch  118  can be rotated with respect to the cover  66  and support member  36  to position the fasteners  130  in alignment with the other notch  72  or  74  corresponding to the desired gear ratio. At that point, the switch  118 can be released and the biasing members  64  will urge the fasteners  130  into the desired notch  72  or  74  to reengage the switch  118  with the cover  66 . Further, the depth of the notches  72  and  74  are formed to enable the locking member  132  to be positioned out of engagement with the sun gear in notch  72 , and in engagement in notch  74 . 
         [0040]    Preferably, the reduced section  124  of the ring  120  also includes indicia  144  thereon to assist in properly positioning the switch  118  in the location for the desired gear ratio. Further, both the support member  36  and the ring gear  98  can have printed indicia  146  on the exterior thereof indicating the gear ratio at which the device  10  is currently operating. This indicia  146  becomes exposed on the particular part of the device  10  when the switch  118  is moved into engagement with the notch  72  or  74  on the cover  66  corresponding to that gear ratio. 
         [0041]    In a second embodiment of the device  200  shown in  FIGS. 8 and 9 , the device  200  includes the ratcheting mechanism  202  positioned on the same end of the housing  204  as the gear mechanism  206 . In this embodiment, the housing  204  is formed of a front portion  208  and a rear portion  210  connected to one another via the shaft  212 . The shaft  212  is connected to the ratcheting mechanism  202  that is disposed a part of the passage  214  formed in the front portion  208 , and extends rearwardly from the mechanism  202  into the rear portion  210 . The passage  214  in the rear portion  210  is formed within a generally rigid inner member  216 , around which is formed a softer material member  218 . The shaft  212  is engaged within the passage  214  by a number of bearings  220  to allow the shaft  212  to rotate without interference from the housing  204 , and is covered opposite the ratcheting mechanism  202  by and end cap  222 . 
         [0042]    In this construction for the device  200 , the support member  36  of the first embodiment is replaced by the inner member  216  of the housing  204 , from which the various attachment members  224  extend. Thus, the cover  226 , and planetary gears  228  are connected directly to the inner member  216 , with the locking member  230  and switch  232  being connected to the cover  226  using the slots (not shown) and the notches (not shown) in the same manner as described above. Additionally, the biasing members  234  are also disposed between the inner member  16  and the locking member  230  to bias the locking member  230  into engagement with the slots in the cover  226 , regardless of the selected gear ratio, in the same manner as described previously. The ring gear  236  is affixed to the front portion  208  and is positioned around and in engagement with the planetary gears  228  in the assembled device  200 . 
         [0043]    In the device  200 , the switch  232  can be moved with regard to the cover  226  as described previously to shift the position of the locking member  230  and cause the rotation of the sun gear  238  on the shaft  212  at the desired ratio 
         [0044]    Various other alternatives are contemplated is being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter regarded as the invention.