Abstract:
The invention provides a ratchet tool that includes a tool head, a drive including a sun gear, a ratchet mechanism, and planet gears mounted to a carrier and meshed with the sun gear. The tool head has drive teeth meshed with the planet gears. The ratchet mechanism is mounted to the tool head and is operative to directly couple the tool head to the input when the tool head is rotated in a first direction and to uncouple the tool head from the input when the tool head is rotated in a second opposite direction. Rotation of the tool head in the second direction, while the user holds the carrier stationary, rotates the drive in the first direction.

Description:
[0001]    This Application claims the benefit of U.S. Provisional Application Ser. No. 61/493,631 filed Jun. 6, 2011. 
     
    
     TECHNICAL FIELD OF THE INVENTION  
       [0002]    The present invention relates to tools, and in particular to ratchet mechanism-type tools. 
       BACKGROUND OF THE INVENTION  
       [0003]    Ratchet mechanism-type tools, such as wrenches, are used to allow for the application of torque to an object, such as a nut or bolt head without the need for the removal and replacement of the wrench upon the nut or bolt head at the end of each rotational movement to apply a further rotational movement. The time necessary to either install or remove a nut or bolt is reduced with these types of wrenches. 
         [0004]    The ability of ratchet type wrenches to accomplish the above time savings is due to an associated lost motion. One direction of rotational movement of the wrench applies torque, while the opposite rotational movement is in effect lost motion, in which no torque is applied. Accordingly, upon the opposite rotational movement, there is no rotation of the nut or bolt. 
         [0005]    Because there is no rotation of the nut or bolt head accomplished when the wrench is rotated in the opposite direction, known ratchet wrenches are less effective in areas where the clearance between surrounding objects and the wrench handle allows only a restricted rotational swing of the handle. In such areas, with the rotation in the opposite direction not adding to the rotational movement of the nut or bolt head, more rotational back-and-forth rotation is necessary in order to install or remove a nut or bolt. 
         [0006]    The present inventor has recognized a need to provide a dual acting ratchet tool that can utilize limited rotation movement of the tool handle in both rotational directions to forcibly rotate an object in a single rotation direction. The present inventor has recognized a need to provide such a tool that is compact in design for use in tight areas with reduced clearance for rotational movement of the tool handle. The present inventor has recognized a need to provide such a tool that is of rugged construction and is cost effectively manufactured. 
       SUMMARY OF THE INVENTION  
       [0007]    The present invention provides a ratchet tool that is compact and effective and which allows for driving an output of the tool is a constant direction during both the drive stroke and the opposite return stroke. 
         [0008]    The invention provides a ratchet tool that includes a tool head, a drive including a sun gear, a ratchet mechanism, a carrier and planet gears. The tool head has a cavity with an drive axis and an inside circumference with drive teeth extending parallel to the drive axis around the inside circumference. The drive teeth can be provided on a separate inner gear fixed into the tool head. The drive includes a drive output to impart rotation to an object such as a nut or bolt head, and a drive input to receive torque for rotating the output. The sun gear of the drive has sun gear teeth extending parallel to the drive axis around an outer circumference of the sun gear. The ratchet mechanism is mounted to the tool head and is operative to directly couple the tool head to the input when the tool head is rotated in a first direction and to uncouple the tool head from the input when the tool head is rotated in a second opposite direction. The carrier has a carrier outside surface engageable by a user&#39;s finger. The carrier is rotationally mounted to the tool head to rotate about the drive axis. 
         [0009]    The plurality of planet gears are spaced-apart and rotationally mounted to the carrier. Each planet gear has planet gear teeth extending parallel to the tool drive axis. The planet gears fit meshed between the drive teeth and the sun gear teeth. Rotation of the tool head in the second direction, while the user holds the carrier outside surface stationary, rotates the drive in the first direction even though the ratchet has uncoupled the tool from the input. 
         [0010]    Accordingly, for example, if the ratchet is set to couple the tool head to the drive in the first direction being a clockwise tightening direction, a bolt head can be tightened when the tool head is rotated in the first direction by torque from the tool head through the ratchet mechanism and into the input. This is the customary operation of a ratchet wrench. The user is not holding the carrier stationary when rotating in this first direction. 
         [0011]    When the tool head is rotated in the return stroke, in the second, opposite direction, that is counterclockwise in this example, the ratchet uncouples the tool head from the input. If during this return stroke the user holds the carrier stationary, the planet gears will drive the sun gear to rotate in the opposite direction of the return stroke, in the first direction, that is clockwise in this example even though the ratchet has uncoupled the tool from the input. Thus, in this example, during rotation of the tool head in both the clockwise and counterclockwise directions, the output is driven in the clockwise direction. 
         [0012]    If the ratchet operation is reversed, for example for loosening a bolt head, the first direction is now counterclockwise and the opposite effect is realized, for both the initial stroke and the return stroke the output is driven counterclockwise. 
         [0013]    As an enhancement, the drive input comprises a cylinder coaxially connected to the sun gear, and wherein the ratchet mechanism comprises at least one pawl mounted to the cylinder and engageable to the drive teeth to prevent relative rotation between the cylinder and the tool head when the tool head is rotated in the first direction but to allow relative rotation between the tool head and the cylinder when the tool head is rotated in the second direction. 
         [0014]    As an exemplary embodiment, the drive output comprises a socket drive. 
         [0015]    As an enhancement, the drive output, the sun gear and the cylinder are all formed together as a unitary part. 
         [0016]    As an exemplary embodiment, the carrier comprises a round disk. 
         [0017]    As an exemplary embodiment, the tool head comprises an outer body and an inner gear fixedly mounted into the outer body, the inner gear providing the drive teeth. 
         [0018]    As an exemplary embodiment, the inner gear has outer threads and the outer body has inner threads and the inner gear is threaded into the outer body. 
         [0019]    As an enhancement, the ratchet mechanism is reversible such that the first direction is either clockwise or counterclockwise. 
         [0020]    As an enhancement, the drive input comprises a cylinder coaxially connected to the sun gear. The ratchet mechanism comprises a selector having a finger-engageable operator connected to a selector shaft that is elongated parallel to the drive axis. A spring tube extends transversely through the selector shaft, and a spring residing inside the spring tube. Pins extend from opposite ends of the spring to be urged away from each other by the spring. Two pawls are each pressed by a pin away from each other. The cylinder has an axial bore to receive the selector shaft and a diametric bore to receive the tube, and the pawls are mounted to the cylinder to extend between the drive teeth and an outside circumference of the cylinder on opposite sides of the cylinder. The pawls are engageable to the drive teeth to prevent relative rotation between the cylinder and the tool head when the tool head is rotated in the first direction but to allow relative rotation between the tool head and the cylinder when the tool head is rotated in the second direction. 
         [0021]    The diametric bore can be oversized or outwardly fan shaped to allow room for rotation of the spring tube about the drive axis within the cylinder. The rotation of the spring tube causes each pin to pivot a respective pawl to a degree that reverses operation of the ratchet mechanism from the first direction being clockwise to the first direction being counterclockwise. 
         [0022]    Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]      FIG. 1  is a side view of a ratchet tool of the present invention; 
           [0024]      FIG. 2  is a rear view of the ratchet tool of  FIG. 1 ; 
           [0025]      FIG. 3  is a front view of the ratchet tool of  FIG. 1 ; 
           [0026]      FIG. 4  is a fragmentary, exploded perspective view of the ratchet tool of  FIG. 1 ; 
           [0027]      FIG. 5  is a fragmentary exploded plan view of the ratchet tool in  FIG. 1 ; 
           [0028]      FIG. 6  is a fragmentary sectional view taken generally along lines  6 - 6  of  FIG. 2 ; and 
           [0029]      FIG. 7  is a fragmentary sectional view taken generally along lines  7 - 7  of  FIG. 6 . 
       
    
    
     DESCRIPTION  
       [0030]    While this invention is susceptible of embodiment in many different forms, there are shown in the drawings, and will be described herein in detail, specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated. 
         [0031]      FIGS. 1-7  illustrate an embodiment of a ratchet tool  8  of the present invention. The tool  8  includes a handle  10 , which can be of a one-piece construction and which includes a tool head  10   a  which also serves as a frame. A carrier disk  12  having a round circumference is located adjacent to a tool head  10   a.  An output drive  14  extends from the tool head  13 . A selector switch  16  having a turning handle  16   a  allows for reversing tool ratchet direction. For purpose of description the tool has a drive axis A, shown in  FIGS. 1 and 6 . 
         [0032]      FIGS. 4-7  illustrates internal parts in more detail. A snap ring  18  and a carrier retainer  20  maintain the tool in an assembled state. Three planet gears  22  having planet gear teeth  22   a  that are elongated in a direction parallel to the drive axis A, are spaced apart and are rotatably mounted on pins  24  or bolts to the carrier  12 . The output drive  14  includes a sun gear  62 , a drive shaft  60  and a base cylinder  63 . The output drive  14  can be of a one-piece unitary construction. 
         [0033]    The selector switch  16  holds a ratchet assembly that includes pawls  28   a,    28   b,  pins  30   a,    30   b,  a spring  32  and a spring tube  34 . When assembled, the pins  30   a,    30   b  are partially inserted into opposite ends of the spring tube  34  with the spring within the spring tube urging the pins  30   a,    30   b  outwardly in opposite directions. 
         [0034]    The switch  16  includes a round head  16   b  upon which extends the handle  16   a.  Extending from the round head  16   b  on an opposite side from the handle  16   a  is a selector shaft  17 . The selector shaft  17  fits with close clearance into a bore  66  in the cylinder  63 . A cross-bore  58  through the selector shaft  17  holds the spring tube  34 . The parts  28   a - 34  fit into the cylinder  63  within an oppositely flared, expanding outwardly, through-passage  67  formed into the cylinder  63  that is open through the bore  66 . The spring tube  34  being captured in the passage  67  and in the cross-bore  58  secures the switch  16  to the cylinder  63 . By rotating the handle  16   a,  the selector shaft  17  rotates within the bore  66  and the spring tube  34  rotates therewith through the through-passage  67 . The spring  32  and the pins  30   a,    30   b  move with the rotating spring tube  34 . 
         [0035]    The sun gear  62  is formed into or cut into the output drive  14 . The sun gear  62  has sun gear teeth  62  that are elongated in a direction parallel to the drive axis A, which mesh with the planetary gear teeth  22   a  of the planetary gears  22 . 
         [0036]    The output shaft  60  fits through parts  18 ,  20  and  12 . The retainer  20  holds the carrier  12  in place. The pins  24  holds planet gears  22  to the carrier via holes  72  which can be threaded to accept threaded pins. 
         [0037]    Within the ratchet mechanism frame, or in this case the tool head  10   a,  a cylindrical cavity  52  of limited depth has internal threads  52   a  to receive the external threads  52   b  of the inner gear  26 . When the inner gear  26  is fully screwed into the cylindrical bore  52  of the tool head  10   a,  a key (not shown) may be inserted firmly secure the two parts together. The inner circumference of the inner gear  26  is machined to have teeth  54  that are elongated in a direction parallel to the drive axis A, to mesh with the planetary gears  22  and the pawls  28   a,    28   b.    
         [0038]    The base cylinder  63  has machined semi-cylindrical seats  64 , located on diametrically opposite sides of the cylinder  63 , which house the ratchet pawls  28   a,    28   b.    
         [0039]    The selector switch head  16   b  has an outer circumference  56  which matches an inner circumference  50  of an opening  51  in the back of the tool head  10   a,  the opening  51  acting as a bearing journal for the switch  16 . 
         [0040]    The carrier disk  12  is thin with a round circumference. An outer edge  12   a  of the carrier disk  12  may be knurled for greater grip. The carrier disk  12  includes an inner round opening  70  for passing the output drive shaft  60  therethrough. 
         [0041]    The carrier disk  12 , including the attached planet gears  22  is held into the tool head  10   a  by the carrier retainer  20 . The retainer has a compound opening  68  with a large section  68   a  and a smaller diameter section  68   b.  The larger opening  68   a  allows for the positioning of the retainer  20  into a slot  12   d  formed into the carrier  12 , wherein the smaller diameter opening section  68   b  will be effectively captured into the slot  12   d  once the retainer  20  is fit onto and then shifted on the carrier  12 . The snap ring  18  surrounds the carrier  12  and snaps into an annular slot  10   c  in the tool head  10   a.  The snap ring  18  abuts the retainer  20  to prevent the retainer  20  and thus the carrier  12  from pulling out of the tool head  10   a.    
         [0042]      FIG. 7  illustrates one type of ratchet pawl arrangement. Only one pawl  28   a  is illustrated with the understanding that the opposite pawl  28   b  is configured rotationally symmetrical about the drive axis A and would operate with in similar fashion in tandem with the first pawl  28   a.  Other types of pawl arrangements are encompassed by the invention including those described in U.S. Pat. Nos. 4,807,500; 4,147,076; 3,467,231; 5,603,393 and 5,537,899; herein incorporated by reference. 
         [0043]    As shown in  FIG. 7 , the pawl  28   a  has a semi-cylindrical outer circumference that fits closely into the semi-cylindrical seat  64 . The pawl  28   a  is captured between the seat  64  and the teeth  54  of the inner gear  26 . When urged by the pin  30   a,  the pawl  28   a  can smoothly rotate within and be guided by the seat  64 . The spring  32  retained in the spring tube  34  urges the pin  30   a  against a right side ( FIG. 7 ) of a slot  28   c  formed on a back side of the pawl  28   a.  This rotates the pawl  28   a  clockwise about a pawl axis  28   d  that is parallel to the drive axis A. An end tooth  28   e  is positioned to engage teeth  54  of the gear  26  while an opposite end tooth  28   f  is drawn away from the teeth  54 . The tooth  28   e  allows the cylinder  63  to relatively rotate with respect to the gear  26  in the cylinder direction R but not in the cylinder direction Q. The left face ( FIG. 7 ) of the tooth  28   e  slips over the teeth  54  when the cylinder relatively rotates in the cylinder direction R but the right face ( FIG. 7 ) of the tooth  28   e  prevents relative rotation between the cylinder  63  and the gear  26  in the cylinder direction Q. When the selector shaft  17  is rotated clockwise in  FIG. 7 , the spring tube is rotated clockwise and the pin  30   a  presses a left side of the slot  28   c  and the pawl  28   a  is rotated counterclockwise about the pawl axis  28   d  until the tooth  28   f  engages the teeth  54  and the tooth  28   e  is drawn away from the teeth  54 . Now, the tooth  28   f  allows the cylinder  63  to relatively rotate with respect to the gear  26  in the cylinder direction Q but not in the cylinder direction R. The right face ( FIG. 7 ) of the tooth  28   f  slips over the teeth  54  when the cylinder relatively rotates in the cylinder direction Q but the left face ( FIG. 7 ) of the tooth  28   f  prevents relative rotation between the cylinder  63  and the gear  26  in the cylinder direction R. 
         [0044]    From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred.