Abstract:
A one-way clutch comprising a driver member, a driven member disposed radially outward of the driver member, a pawl cooperatively engaged with a receiving portion in the driver member, a recess in the driven member for receiving the pawl, a pawl guide engaged with the driven member, and the pawl engaged with the pawl guide, the pawl guide having a first portion and a second portion, the first portion urging the pawl radially outward to engage the recess for a driving condition and the second portion urging the pawl radially inward to disengage the recess for an overrun condition.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to a one-way clutch comprising a pawl guide engaged with a pawl having a first portion and a second portion, the first portion orienting the pawl radially outward into contact with a driven member recess for a driving condition and the second portion orienting the pawl radially inward out of contact with the recess for an overrun condition. 
       BACKGROUND OF THE INVENTION 
       [0002]    This invention relates to one-way clutches for rotating devices. Often rotating power transmission devices have the need for a one way clutch to allow free rotation in one direction and power transmission in the other rotating direction. It is common to incorporate a sprag type, roller type, or wrap-spring type one-way clutch in these devices. These common clutches can be complex, high precision, limited in capacity, require excessive space and can require precision mating components. 
         [0003]    Representative of the art is U.S. Pat. No. 7,000,749 which discloses a ratchet one-way clutch. including an inner race, an outer race provided coaxially with the inner race, a pawl member for transmitting torque between the inner race and the outer race, and a damper mechanism for absorbing shock at the time of engagement of the pawl member, a sliding plate is interposed between two members which constitute the damper mechanism and are rotatable relative to each other. 
         [0004]    What is needed is a one-way clutch comprising a pawl guide engaged with a pawl having a first portion and a second portion, the first portion orienting the pawl radially outward into contact with a driven member recess for a driving condition and the second portion orienting the pawl radially inward out of contact with the recess for an overrun condition. The present invention meets this need. 
       SUMMARY OF THE INVENTION 
       [0005]    The primary aspect of the invention is a one-way clutch comprising a pawl guide engaged with a pawl having a first portion and a second portion, the first portion orienting the pawl radially outward into contact with a driven member recess for a driving condition and the second portion orienting the pawl radially inward out of contact with the recess for an overrun condition. 
         [0006]    Other aspects of the invention will be pointed out or made obvious by the following description of the invention and the accompanying drawings. 
         [0007]    The invention comprises a one-way clutch comprising a driver member, a driven member disposed radially outward of the driver member, a pawl cooperatively engaged with a receiving portion in the driver member, a recess in the driven member for receiving the pawl, a pawl guide engaged with the driven member, and the pawl engaged with the pawl guide, the pawl guide having a first portion and a second portion, the first portion urging the pawl radially outward to engage the recess for a driving condition and the second portion urging the pawl radially inward to disengage the recess for an overrun condition. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The accompanying drawings, which are incorporated in and form a part of the specification, illustrate preferred embodiments of the present invention, and together with a description, serve to explain the principles of the invention. 
           [0009]      FIG. 1  is a front view of the device. 
           [0010]      FIG. 2  is an exploded view of the device. 
           [0011]      FIG. 3   a  is a detail of the device in the driving condition. 
           [0012]      FIG. 3   b  is a detail of the device in the overrun condition. 
           [0013]      FIG. 4  is a perspective detail of the device. 
           [0014]      FIG. 5  is a perspective view of an alternate embodiment. 
           [0015]      FIG. 6  is an exploded view of the device. 
           [0016]      FIG. 7  is a perspective view of an alternate embodiment. 
           [0017]      FIG. 8  is a perspective view of an alternate embodiment. 
           [0018]      FIG. 9  is an exploded view of an alternate embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0019]      FIG. 1  is a front view of the device. The inventive device consists of a driver member  10 , pawl  20 , pawl guide  30  and a driven member  40 . Driven member  40  is disposed radially outward of driver member  10 . Driver member  10  is oriented such that it is in contact with the pawl  20 . Pawl  20  is oriented such that it is in contact with driven member  40  and pawl guide  30 . Pawl  20  engages a recess  41  in driven member  40 . A plurality of recesses  41  are disposed about the inner perimeter of the driven member  40 . Pawl  20  comprises a pin  21  by which it engages pawl guide  30 . Pawl guide  30  engages a hub  42  of driven member  40 . Hub  42  is connectable to a driven shaft (not shown). 
         [0020]      FIG. 2  is an exploded view of the device. Driver member  10  comprises a recess  11  which cooperatively receives pawl  20 . Pawl guide  30  comprises a portion  31  which is configured to engage pin  21  of pawl  20 . Pawl guide  30  may comprise spring steel or other suitably rigid material. Recesses  41  are disposed about the entire inner perimeter of driven member  40 . Driver member  10  is cooperatively received in recess  44 . Recess  44  extends about the entire circumference of driven member  40 . Engaging driver member  10  within recess  44  allows pawl  20  to align with recesses  41 . Recesses  41  are inclined at an angle θ to a tangent to driven member  40 , see  FIG. 1 . Angle θ is in the range of greater than 0 degrees to approximately 30 degrees. 
         [0021]      FIG. 3   a  is a detail of the device in the driving condition. Recess  11  of driver member  10  cooperatively receives the pawl  20 . Pawl  20  is engaged with recess  41  and pawl guide  30 . In the orientation shown in  FIG. 3   a , counter clockwise rotational power is transmitted from the driver member  10  to the pawl  20  to the driven member  40 . Pawl  20  rotates radially outward to engage recess  41  in the driving condition by operation of in  21  translating within portion  32 , see  FIG. 3   b . In the driving condition a driver portion (not shown) engages slot  110 . A driver portion engages the end  110   a  of slot  110  in a driving direction. Slot  110  extends about an outer circumference of driver member  10 . 
         [0022]      FIG. 3   b  is a detail of the device in the overrun condition. Pawl  20  is shown with the clutch in the disengaged position. Pawl  20  is fully disengaged from driven member  40  and recess  41 . This position occurs when the driven member  40  rotates faster than the driver member  10 , also known as overrun. As one can see, pawl  20  is fully disengaged from recess  41  thereby allowing driven member  40  to rotate freely past the driver member  10  in the counter clockwise direction D1, known as the overrun condition. 
         [0023]    As the overrun condition occurs pawl guide  30  rotates with driven member  40  because it is engaged with hub  42  in groove  43 , and therefore pawl guide  30  rotationally temporarily overtakes driver member  10 . In doing so, pin  21  of pawl  20  moves radially inward along guide  30  from portion  32  to portion  33 . Portion  32  has a larger radius from the center of the device compared to the radius to portion  33  thereby causing the radially inward movement. Pin  21  engages portion  32  in the driving condition. Pin  21  engages portion  33  in the overrun condition. Movement from portion  32  to portion  33  causes pawl  20  to pivot and thereby retract from recess  41  in the overrun condition. Further, engagement of pin  20  with recess  11  facilitates retraction of pawl  20  in the overrun condition. 
         [0024]    To reengage the pawl in the driving condition, pawl  20  and driver member  10  rotate relative to the driven member  40  and pawl guide  30  in direction D1. Pin  21  moves from portion  33  to portion  32  of pawl guide  30 . This movement forces pawl  20  to pivot radially outward thus engaging with a recess  41 . If the orientation is such that the pawl is not immediately in contact with a recess  41 , the driver member  10  and pawl  20  rotate CCW together (direction D1) until the pawl contacts with the driven member recess  41 , thus engaging the clutch assembly into the driving condition. 
         [0025]    Pawl  20  pivots through an angle β of approximately 30 degrees as it moves from the overrun condition to the driving condition and vice versa. 
         [0026]      FIG. 5  is a perspective view of an alternate embodiment. This alternate embodiment of the inventive device comprises a plurality of pawls  20  spaced radially around the device. Unless indicated otherwise, this alternate embodiment has the same pawls and features as described in this specification. Pawls  20  are shown in the overrun configuration in  FIG. 5 . 
         [0027]      FIG. 6  is an exploded view of the device. In the overrun condition projecting portion  12  progressively engages pawl surface  22 , thereby facilitating retraction of pawl  20  from recess  41  into receiving portion  11  during the overrun condition. 
         [0028]      FIG. 7  is a perspective view of an alternate embodiment. Unless noted otherwise the components and manner of operation of this alternate embodiment is unchanged from the embodiment in  FIGS. 1-6 . 
         [0029]    Driver member  100  is engaged. with driven member  400 . Driven member  400  can engage an output shaft (not shown). Pawl  200  is cooperatively received in recess  120 , see  FIG. 9 . Pawl  200  engages recess  410  in a driving condition. Pawl guide  300  retains and guides pin  210  and thereby pawl  200 . Pin  210  is guided by pawl guide  300  in a like manner as described for pawl guide  30 . Pawl  200  fully resides in recess  120  in the overrun condition so as not to engage a recess  410 . Pawl guide  300  engages groove  430  in driven member  400 . 
         [0030]    In the driving condition driver member  100  will rotate past the driven member  400  in direction “D”. Pawl. guide  300  is engaged with groove  430 , causing it to rotate with driven member  400 . As driver member  100  moves relative to driven member  400  in direction “D” pin  210  moves relative to pawl guide  300  in a radially inward direction along portion  330 , see  FIG. 8 , thereby causing pawl  200  to engage recess  410 . This in turn will drive driven member  400 . 
         [0031]      FIG. 8  is a perspective view of the alternate embodiment. In the overrun condition driver member  100  will move in direction “D2” relative to driven member  400 . In doing so pin  210  will move relative to pawl guide  300  in a radially outward direction along portion  330  to portion  320 , thereby causing pawl  200  to fully retract or disengage from recess  410  and thereby reengage recess  120 , which allows driven member  400  to overrun driver member  100 . 
         [0032]      FIG. 9  is an exploded view of alternate embodiment. Driver member  100  comprises a recess  121  which cooperatively receives portion  330 . This allows the overall thickness of the device in the axial direction to be kept to a minimum. Axial direction refers to the rotational axis of the device. 
         [0033]    Although a form of the invention has been described. herein, it will be obvious to those skilled in the art that variations may be made in the construction and relation of parts without departing from the spirit and scope of the invention described herein.