Abstract:
A spindle lock assembly ( 410, 710 ) for a power tool ( 10 ) includes a first rotatable part ( 904, 704 ) fixedly connected to an output member ( 404 ) of a power tool transmission ( 16 ), and a second rotatable part ( 426, 726 ) fixedly connected to the power tool output spindle ( 430 ) and operatively engaging the first rotatable part. A lock ring ( 908, 708 ) surrounds the first and second rotatable parts. The lock ring being is retained in the housing in a substantially stationary manner with a dampener ( 954, 754 ) disposed between the lock ring and the power tool housing ( 772 ) and to dampen movements of the lock ring relative to the housing in a rotational direction. The spindle lock assembly transmits rotary motion from the transmission output member to the output spindle when the rotary output member is being driven by the motor and inhibits transmittal of rotary motion from the output spindle to the transmission output member when the output spindle is driven by an external force.

Description:
RELATED APPLICATION 
       [0001]    This application claims priority, under 35 U.S.C. §120, as a continuation of PCT Application No. PCT/CN2013/090154, filed Dec. 20, 2013, which is incorporated by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    This application relates to a spindle lock assembly for a power tool, such as a power drill or driver. 
       BACKGROUND 
       [0003]    A spindle lock may be incorporated into a power tool, such as a drill or driver. A spindle lock may be configured to transmit rotary motion from a rotatable output member of a transmission to an output spindle of the power tool when the input member of the transmission is being driven by the motor, and may be configured to prevent or inhibit transmission of rotary motion from the output spindle to the transmission when the output spindle is being driven by an external force (also known as back-driving the transmission). Examples of spindle locks are illustrated in U.S. Pat. Nos. 7,980,324 and 8,205,685, which are incorporated by reference in their entirety. 
         [0004]    When the motor is turned on, the motor drives the transmission, which transmits rotary motion through the spindle lock to the output spindle. When the motor is turned off, the motor and transmission decelerate. At the same time, the output spindle still has a great deal of momentum and continues to attempt to rotate relative to the transmission. When the output spindle attempts to rotate, the spindle lock engages to prevent back-driving of the transmission. However, if the motor and transmission rapidly decelerate (e.g., by braking the motor instead of allowing it to coast to a stop), the spindle lock may rapidly engage. This can cause undesirable noise and wear on the spindle lock components. This can also cause rapid deceleration of a tool holder or chuck that is attached to the output spindle, which may result in the tool holder or chuck loosening its grip on an accessory. 
       SUMMARY 
       [0005]    In an aspect, a power tool includes a housing assembly, a motor received in the housing assembly, an output spindle, and a transmission configured to transmit rotary power between the motor and the output spindle. The transmission includes a rotatable output member. A spindle lock assembly is configured to transmit rotary motion from the rotatable output member to the output spindle when the rotary output member is being driven by the motor and configured to inhibit transmittal of rotary motion from the output spindle to the rotary output member when the output spindle is being driven by an external force. The spindle lock assembly includes a first rotatable part fixedly connected to the output member, a second rotatable part fixedly connected to the output member and operatively engaging with the first rotatable part, and a lock ring surrounding the first rotatable part and the second rotatable part. The lock ring is retained to the housing in a substantially stationary manner with at least one dampener disposed between the lock ring and the housing and configured to dampen movements of the lock ring relative to the housing in a rotational direction. 
         [0006]    Implementations of this aspect may include one or more of the following features. The transmission may include a planetary gear transmission having a sun gear, a planet gear, a ring gear, and a carrier that carries the planet gear, where the output member includes the carrier. The first rotatable part may include a plurality of axial lugs extending from the carrier. The second rotatable part may include an anvil fixedly attached to the spindle. The spindle lock assembly may include a plurality of rollers, each roller disposed between adjacent ones of the lugs and between an outer surface of the anvil and an inner surface of the lock ring. The lock ring may include a radially outwardly extending projection received in a recess in the housing, with the dampener disposed between the projection and a sidewall of the recess. The dampener may include a first dampener disposed between the projection and a first sidewall of the recess to dampen movement of the lock ring in a clockwise rotational direction and a second dampener between the projection and a second sidewall of the recess to dampen movement of the lock ring in a counterclockwise rotational direction. The dampener may include an elastomeric plug and/or a spring. The dampener allows for rotational movement of the lock ring relative to the housing by up to approximately 20 degrees, e.g., approximately 2 degrees to approximately 15 degrees or approximately 3 degrees to approximately 17 degrees. 
         [0007]    In another aspect, a spindle lock assembly is disclosed for incorporation into a power tool that includes a housing assembly, a motor received in the housing assembly, an output spindle, and a transmission configured to transmit rotary power between the motor and the output spindle. The spindle lock assembly includes a first rotatable part fixedly connected to the transmission, and a second rotatable part fixedly connected to the output spindle and operatively engaging with the first rotatable part. A lock ring surrounds the first rotatable part and the second rotatable part. The lock ring being is retained in the housing in a substantially stationary manner with a dampener disposed between the lock ring and the housing and configured to dampen movements of the lock ring relative to the housing in a rotational direction. The spindle lock assembly is configured to transmit rotary motion from the rotatable output member to the output spindle when the rotary output member is being driven by the motor and is configured to inhibit transmittal of rotary motion from the output spindle to the rotary output member when the output spindle is being driven by an external force. 
         [0008]    Implementations of this aspect may include one or more of the following features. The transmission may include a planetary gear transmission having a sun gear, a planet gear, a ring gear, and a carrier that carries the planet gear. The first rotatable part may include a plurality of axial lugs extending from the carrier. The second rotatable part may include an anvil fixedly attached to the spindle. The spindle lock assembly may include a plurality of rollers, each roller disposed between adjacent ones of the lugs and between an outer surface of the anvil and an inner surface of the lock ring. The lock ring may include a radially outwardly extending projection received in a recess in the housing, with the dampener disposed between the projection and a sidewall of the recess. The dampener may include a first dampener disposed between the projection and a first sidewall of the recess to bias movement of the lock ring in a clockwise rotational direction and a second dampener between the projection and a second sidewall of the recess to dampen movement of the lock ring in a counterclockwise rotational direction. The dampener may include at least one of an elastomeric plug and/or a spring. The dampener allows for rotational movement of the lock ring relative to the housing by up to approximately 20 degrees, e.g., approximately 2 degrees to approximately 15 degrees or approximately 3 degrees to approximately 17 degrees. 
         [0009]    In another aspect, a power tool includes a housing assembly, a motor received in the housing assembly, an output spindle, and a transmission configured to transmit rotary power between the motor and the output spindle. The transmission includes a rotatable output carrier. A spindle lock assembly is configured to transmit rotary motion from the rotatable output member to the output spindle when the rotary output member is being driven by the motor and configured to inhibit transmittal of rotary motion from the output spindle to the rotary output member when the output spindle is being driven by an external force. The spindle lock assembly includes a plurality of axial lugs fixedly connected to the output carrier, an anvil fixedly connected to the output spindle and operatively engaging with the axial lugs. A lock ring surrounds the axial lugs and the anvil. A plurality of rollers is disposed between adjacent lugs and between an outer surface of the anvil and an inner surface of the lock ring. The lock ring is retained to the housing in a substantially stationary manner by a radially outwardly extending projection received in a recess of the housing. A first dampener is disposed between the projection and a first sidewall of the recess to dampen movement of the lock ring in a clockwise rotational direction and a second dampener disposed between the projection and a second sidewall of the recess to dampen movement of the lock ring in a counterclockwise rotational direction. 
         [0010]    Advantages may include one or more of the following. The damped rotational movement of the lock ring will reduce the noise associated with the spindle lock assembly when it is engaged to prevent back-driving of the transmission. The damped rotational movement of the lock ring will also reduce peak deceleration of the output spindle and the attached chuck due to excess momentum in the output spindle when the motor is depowered and/or braked. This will reduce instances of damage to the spindle lock assembly components and reduce instances of the chuck unlocking during deceleration. These and other advantages and features will be apparent from the description, the drawings, and the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present teachings. 
           [0012]      FIG. 1  is a side view of a power tool constructed in accordance with the present teachings. 
           [0013]      FIG. 2  is an exploded perspective view of a portion of the power tool of  FIG. 1 . 
           [0014]      FIG. 3  is a more detailed exploded perspective view of a portion of the power tool of  FIG. 1 . 
           [0015]      FIG. 4  is a perspective view of a first embodiment of a spindle lock assembly in accordance with the present teachings. 
           [0016]      FIG. 5  is an exploded view of the spindle lock assembly of  FIG. 4 . 
           [0017]      FIG. 6  is a front view of the spindle lock assembly of  FIG. 4 . 
           [0018]      FIG. 7  is a front view of a second embodiment of a spindle lock assembly in accordance with the present teachings. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    The following description merely exemplary in nature and is not intended to limit the present teachings, its application, or uses. It should be understood that throughout the drawings corresponding reference numerals indicate like or corresponding parts and features. 
         [0020]    With reference to  FIGS. 1 and 2 , a power tool constructed in accordance with the present teachings is generally indicated by reference numeral  10 . Various aspects of the present teachings may include either a cord or a cordless (battery operated) device, such as a portable screwdriver or a drill (e.g., drill, hammer drill and/or driver). In  FIG. 1 , the power tool  10  is illustrated as a cordless drill having a housing  12 , a motor assembly  14 , a multi-speed transmission assembly  16 , a clutch mechanism  18 , an output spindle assembly  20  (including a hammer mechanism  19 , an output spindle housing  772 , and an output spindle  430 ) contained within a spindle housing  21 , a chuck  22 , a trigger assembly  24 , a battery pack  26  and a holder  28 . It will be appreciated that a detailed discussion of several of the components of the power tool  10 , such as the hammer mechanism  19 , the chuck  22 , the trigger assembly  24  and the battery pack  26 , are outside the scope of the present disclosure. Reference, however, may be made to U.S. Pat. Nos. 6,676,557, 6,857,983, 7,220,211, 7,537,064, 6,984,188, 7,101,300, 6,502,648, and 7,314,097, which are incorporated by reference in their entirety, for an understanding of the operation and/or features that may be included in combination or individually with the power tool  10 . 
         [0021]    With reference to  FIG. 2 , the housing  12  may include an end cap assembly  30  and a handle shell assembly  32  that may include a pair of mating handle shells  34 . In one aspect, one mating handle shell may be referred to as the assembly side, while the other side may be referred to as the cover side. The handle shell assembly  32  may include a handle portion  36  and a drive train or a body portion  38 . The trigger assembly  24  and the battery pack  26  may be mechanically coupled to the handle portion  36  and may be electrically coupled to the motor assembly  14 . The body portion  38  may include a motor cavity  40  and a transmission cavity  42 . The motor assembly  14  may be housed in the motor cavity  40  and may include a rotatable output shaft  44 , which may extend into the transmission cavity  42 . A motor pinion  46  having a plurality of gear teeth  48  may be coupled for rotation with the output shaft  44 , as illustrated in  FIG. 3 . The trigger assembly  24  and the battery pack  26  may cooperate to selectively provide electrical power to the motor assembly  14  in a suitable manner to selectively control the speed and/or direction at which output shaft  44  may rotate. 
         [0022]    With additional reference to  FIG. 3 , the transmission assembly  16  may be housed in the transmission cavity  42  and may include a speed selector mechanism  60 . The motor pinion  46  may couple the transmission assembly  16  to the output shaft  44  of the motor  14  to transmit a relatively high speed but relatively low torque drive input to the transmission assembly  16 . The transmission assembly  16  may include a plurality of reduction elements or reduction gearsets that may be selectively engaged (and disengaged) by the speed selector mechanism  60  to provide a plurality of user-selectable speed ratios. Each of the speed ratios may multiply the speed and the torque of the drive input in a predetermined manner, permitting the output speed and the torque of the transmission assembly  16  to be varied in a desired manner between a relatively low speed but high torque output and a relatively high speed but low torque output. The output from the transmission assembly  16  may be transmitted to the output spindle assembly  20  via a spindle lock assembly  410 , as described in greater detail below. The chuck  22  may be incorporated in or coupled for rotation with the output spindle assembly  20  to permit torque to be transmitted to, for example, a tool bit (not shown). The clutch mechanism  18  may be coupled to the transmission assembly  16  and may be operable for limiting the magnitude of the torque associated with the drive input to a predetermined and selectable torque limit. 
         [0023]    The transmission assembly  16  may be a three-stage, three-speed transmission that may include a transmission sleeve  200 , a reduction gearset assembly  202  and the speed selector mechanism  60 . The reduction gearset assembly  202  may include a first reduction gear set  302 , a second reduction gear set  304  and a third reduction gear set  306 . The first, second and third reduction gear sets  302 ,  304  and  306  may be operable in an active mode, and the second and third reduction gear sets  304  and  306  may also be operable in an inactive mode, depending on the position of the speed selector mechanism  60 . The first reduction gear set  302  may include the motor pinion  46  (which functions as a first sun gear), a first reduction element or the first ring gear  310 , a first set of planet gears  312  and a first planet or reduction carrier  314 . The first ring gear  310  may be an annular structure, having a plurality of gear teeth  310  a formed along its interior diameter. The first reduction carrier  314  may be formed in the shape of a flat cylinder, having plurality of pins  322  that extend from its rearward face  324  (i.e., toward the motor pinion  46 ), each carrying one of the planet gears  312 . A plurality of gear teeth  314  a may be formed into the outer periphery of the first reduction carrier  314 . 
         [0024]    The second reduction gear set  304  may be disposed within the portion of the hollow cavity  206  defined by the first housing portion  227  and may include a second sun gear  358 , a second reduction element or ring gear  360 , a second set of planet gears  362  and a second planet or reduction carrier  364 . The second sun gear  358  may be fixed for rotation with the first reduction carrier  314 . The second sun gear  358  may include a plurality of gear teeth  358  that may extend forwardly (i.e., away from the motor pinion  46 ) of the forward face  328  of the first reduction carrier  314 . The second ring gear  360  may be an annular structure, having a plurality of gear teeth  360  a formed along an interior surface associated with its inner diameter. The second reduction gearset  304  may include the second reduction carrier  364  having a plurality of pins  366  holding the second set of planet gears  362 . 
         [0025]    The third reduction gear set  306  may be disposed within the portion of the hollow cavity  206  defined by the second housing portion  229  and may include a third sun gear  398 , a third reduction element or ring gear  400 , a third set of planet gears  402  and a third planet or reduction carrier  404 . The third sun gear  398  may be fixed for rotation with the second reduction carrier  364  and may include a plurality of gear teeth  398  that may be meshingly engaged to the third set of planet gears  402 . The third planet carrier  404  may be generally similar to the first planet carrier  314  and may be employed to journal the third set of planet gears  402 . The third ring gear  400  may be an annular structure having a plurality of gear teeth  400  a formed along its inner periphery associated with an interior diameter. 
         [0026]    With additional reference to  FIGS. 4-6 , the spindle lock assembly  410  may include the third (output) stage planet carrier  404  of the transmission, an anvil  426 , a plurality of rollers or pins  902 , and a lock ring  908 . The anvil  426  is fixedly connected to the output spindle  430  by an opening  976  in the anvil having two flat sides  977  so that the anvil  426  and output spindle  430  will rotate together as a unit. The anvil further includes a plurality of alternating cam surfaces  978  and flat surfaces  979  on its periphery. The carrier  404  is fixedly connected to a plurality of lugs  904  that project axially forward from the carrier  404  and that rotate together with the carrier  404 . The lugs  904  each have a flat inner surface  905 , a flat outer surface  907  and curved end surfaces  909  connecting the flat inner surface  905  and flat outer surface. 
         [0027]    As shown in FIGS,  4  and  6 , the anvil  426  is received between the lugs  904  so that the anvil  426  and lugs  904  are operatively engaged with the flat inner surfaces  905  abutting the flat outer surfaces  979  of the anvil  426 . The lock ring  908  surrounds the anvil  426  and lugs Each of the plurality of pins  902  is freely received in a space or pocket  911  defined between adjacent lugs  904  and between a cam surface  978  of the anvil  426  and an inner surface  913  of the lock ring  908 . 
         [0028]    As shown in  FIG. 5 , the carrier  404  optionally includes a central opening  910  that receives an optional rearward projection  912  on the anvil  426 . In the illustrated embodiment, the central opening  910  and the rearward projection  912  each have a polygonal cross-section that mesh with one another to enable a small amount of rotational movement or play between the anvil  426  and carrier  404  (e.g, up to approximately 30 degrees of relative rotation). It should be understood that the shapes of the central opening  910  and rearward projection  912  may be different, e.g., circular, to enable greater, lesser, or unlimited relative rotation between the anvil and carrier. It should also be understood that the central opening  910  and rearward projection  912  may be omitted without departing from the scope of this disclosure. 
         [0029]    As shown in  FIG. 6 , the lock ring  908  is retained in the housing  778  in a substantially stationary manner by a plurality of projections  950  extending radially outward from the lock ring  908 . Each projection is received in a corresponding recess  952  in the housing  778 . Each recess  952  is slightly wider than the corresponding projection  950  so as to permit a small amount of rotational movement or play between the lock ring  950  and housing  772 . The small amount of rotational movement is damped by a plurality of dampeners  954 , each received between a sidewall  956  of the recess  952  and a sidewall  958  of the projection  950 . In the illustrated embodiment, the dampeners  954  are each composed of an elastomeric (e.g., rubber) plug. This arrangement enables a small amount of damped rotational movement of the lock ring  950  relative to the housing  772 . For example, the lock ring may be able to move by an angle a of less than approximately 20 degrees, e.g., between approximately 2 degrees and approximately 15 degrees. 
         [0030]    In operation, the lugs  904 , the cam surfaces  978  of the anvil  426 , and the interior surface  913  of the lock ring  908  work together so that when the output carrier  426  is driven by the motor and transmission, the lugs  904 , the rollers  902 , and the anvil  426  rotate freely within the lock ring  908 , while the lock ring  908  remains stationary, to enable transmission of torque from the output carrier  404  to the spindle  430 . When the output spindle  430  is driven by an external force (such as by manual input when the user is tightening or loosening the chuck, or by excess momentum of the output spindle  430  when the motor is braked), the spindle  430  and the anvil  426  rotate together to cause the rollers  902  to be pinched between the inner wall  913  of the lock ring  908 , the cam surface  978  of the anvil  426 , and the lugs  904  of the output carrier  404 , which prevents or inhibits back driving of the transmission. 
         [0031]    At the same time, the lock ring will be able to undergo a small, damped rotational movement due to compression of the dampers  954  in either the clockwise or counterclockwise direction. This damped rotational movement will reduce the noise associated with the spindle lock assembly when it is engaged to prevent back-driving of the transmission. This damped rotational movement will also reduce peak deceleration of the output spindle and the attached chuck due to excess momentum in the output spindle when the motor is depowered and/or braked. This will reduce instances of damage to the spindle lock assembly components and reduce instances of the chuck unlocking during deceleration. 
         [0032]    Referring to  FIG. 7 , in an alternative embodiment, the spindle lock assembly  710  may include the third (output) stage planet carrier  404  of the transmission, an anvil  726 , a plurality of rollers or pins  702 , and a lock ring  708 . The anvil  726  is fixedly connected to the output spindle  430  by an opening  776  in the anvil having two flat sides so that the anvil  726  and output spindle  430  will rotate together as a unit. The anvil further includes a plurality of alternating flat surfaces  778  and concave outer surfaces  779  on its periphery. The carrier  404  is fixedly connected to a plurality of lugs  704  that project axially forward from the carrier  404  and that rotate together with the carrier  404 . The lugs  704  each have a convex inner surface  705 . 
         [0033]    The anvil  726  is received between the lugs  704  so that the anvil  726  and lugs  704  are operatively engaged with the convex inner surfaces  705  abutting the concave outer surfaces  779  of the anvil  726 . The lock ring  708  surrounds the anvil  726  and lugs  704 . Each of the plurality of pins  702  is freely received in a space or pocket  711  defined between adjacent lugs  704  and between a flat surface  778  of the anvil  726  and an inner surface  713  of the lock ring  708 . 
         [0034]    The lock ring  708  is retained in the housing  772  in a substantially stationary manner by a plurality of projections  750  extending radially outward from the lock ring  708 . Each projection is received in a corresponding recess  752  in the housing  772 . Each recess  752  is wider than the corresponding projection  750  so as to permit a small amount of rotational movement or play between the lock ring  750  and housing  772 . The small amount of rotational movement is damped by a plurality of dampeners  754 , each received between a sidewall  756  of the recess  752  and a sidewall  758  of the projection  750 . In the illustrated embodiment, the dampeners  754  are each a compression spring. This arrangement enables a small amount of damped rotational movement of the lock ring  750  relative to the housing  772 . For example, the lock ring may be able to move by an angle β of less than approximately 20 degrees, e.g., between approximately 3 degrees and approximately 17 degrees, and more particularly approximately 10 degrees. 
         [0035]    In operation, the lugs  704 , the flat surfaces  778  of the anvil  726 , and the interior surface  713  of the lock ring  708  work together so that when the output carrier  404  is driven by the motor and transmission, the lugs  704 , the rollers  702 , and the anvil  726  rotate freely within the lock ring  708 , while the lock ring  708  remains stationary, to enable transmission of torque from the output carrier  404  to the spindle  430 . When the output spindle  430  is driven by an external force (such as by manual input when the user is tightening or loosening the chuck, or by excess momentum of the output spindle  430  when the motor is braked), the spindle  430  and the anvil  726  rotate together to cause the rollers  702  to be pinched between the inner wall  713  of the lock ring  708 , the flat surface  778  of the anvil  726 , and the lugs  704  of the output carrier  404 , which prevents or inhibits back driving of the transmission. 
         [0036]    At the same time, the lock ring will be able to undergo a small, damped rotational movement due to compression of the spring dampers  754  in either the clockwise or counterclockwise direction. This damped rotational movement will reduce the noise associated with the spindle lock assembly when it is engaged to prevent back-driving of the transmission. This damped rotational movement will also reduce peak deceleration of the output spindle and the attached chuck due to excess momentum in the output spindle when the motor is depowered and/or braked. This will reduce instances of damage to the spindle lock assembly components and reduce instances of the chuck unlocking during deceleration. 
         [0037]    Numerous modifications may be made to the exemplary implementations described above. For example, other spindle lock assembly designs may have different configurations and geometries of the spindle lock components (e.g., number and geometry of rollers and number and geometry of lugs, lock ring, and anvil surfaces). In addition, other types of configurations of dampeners may be used on the lock ring to dampen rotational movement and to soften output spindle deceleration. These and other implementations are within the scope of the following claims.