Drive mechanism and power tool

Abstract

A drive mechanism for a power tool, a power tool and a reciprocating saw. The power tool includes a housing, a motor supported by the housing and including a drive shaft, an output member supported by the housing and adapted to support a tool element, and a drive mechanism. The drive mechanism includes a drive assembly driven by the drive shaft for rotation about an axis, the drive assembly including a gear, a hub selectively driven by the gear for rotation about the axis, and structure positioned between the gear and the hub, the structure selectively transmitting drive force between the gear and the hub and selectively allows relative movement between the gear and the hub. The drive mechanism may also include a drive arm drivingly connected between the drive assembly and the output member of a tool, and the drive arm may be configured to absorb an impact.

1 . A drive mechanism for a power tool, the power tool including a motor including a drive shaft and an output member adapted to support a tool element, the drive mechanism comprising: 
 a gear driven by the drive shaft for rotation about an axis;    a hub selectively driven by the gear for rotation about the axis, the hub being movable relative to the gear, the hub including a drive member offset from the axis;    a drive arm connecting the drive member to the output member to convert rotation of the hub to reciprocation of the output member; and    an elastic member positioned between the gear and the hub member to selectively transmit drive force from the gear to the hub, the elastic member being compressible to selectively allow relative movement between the gear and the hub, the elastic member including a first elastic element and a second elastic element.    
   
   
       2 . The drive mechanism of  claim 1 , wherein the first elastic element is formed of an elastomeric material.  
   
   
       3 . The drive mechanism of  claim 1 , wherein the second elastic element includes a compression spring.  
   
   
       4 . The drive mechanism of  claim 1 , wherein the first elastic element is integrally formed with the second elastic element.  
   
   
       5 . The drive mechanism of  claim 1 , wherein the power tool is a reciprocating saw, wherein the output member is a spindle, wherein the tool element is a saw blade operable to cut a workpiece, and wherein together the first and second elastic elements absorb an impact resulting from a blade lock-up.  
   
   
       6 . The drive mechanism of  claim 1 , wherein the gear defines a pocket and includes a gear protrusion in the pocket, and wherein a portion of the hub is supported in the pocket and includes a hub protrusion, the gear protrusion drivingly engaging the hub protrusion.  
   
   
       7 . The drive mechanism of  claim 6 , wherein at least a portion of the elastic member is positioned between the gear protrusion and the hub protrusion.  
   
   
       8 . The drive mechanism of  claim 6 , wherein the elastic member includes a body, the first elastic element extending radially outwardly from the body between the gear protrusion and the hub protrusion.  
   
   
       9 . The drive mechanism of  claim 8 , wherein the second elastic member is positioned adjacent to the first elastic member and between the gear protrusion and the hub protrusion.  
   
   
       10 . The drive mechanism of  claim 6 , wherein the hub defines an aperture extending axially through the hub and providing access to the elastic member.  
   
   
       11 . The drive mechanism of  claim 1 , wherein the first elastic member is compressible to absorb an impact within a first range, and wherein the second elastic member is compressible to absorb an impact within a second range.  
   
   
       12 . A drive mechanism for a power tool, the power tool including a motor including a drive shaft and an output member adapted to support a tool element, the drive mechanism comprising: 
 a gear driven by the drive shaft for rotation about an axis;    a hub selectively driven by the gear for rotation about the axis, the hub being movable relative to the gear, the hub including a drive member offset from the axis and connected to the output member to drivingly connect the hub to the output member and to convert rotation of the hub to reciprocation of the output member; and    an elastic member positioned between the gear and the hub to selectively transmit drive force from the gear to the hub, the elastic member including a first elastic element and a second elastic element, the first elastic element being compressible to absorb an impact within a first range and the second elastic element being compressible to absorb an impact within a second range.    
   
   
       13 . The drive mechanism of  claim 12 , wherein the elastic member is compressible to selectively allow relative movement between the gear and the hub.  
   
   
       14 . The drive mechanism of  claim 12 , wherein the first elastic element is formed of an elastomeric material.  
   
   
       15 . The drive mechanism of  claim 12 , wherein the second elastic element is a compression spring.  
   
   
       16 . The drive mechanism of  claim 12 , wherein the first elastic element is integrally formed with the second elastic element.  
   
   
       17 . The drive mechanism of  claim 12 , wherein the power tool is a reciprocating saw, wherein the output member is a spindle, wherein the tool element is a saw blade operable to cut a workpiece, and wherein together the first and second elastic elements absorb an impact resulting from a blade lock-up.  
   
   
       18 . The drive mechanism of  claim 12 , wherein the gear defines a pocket and includes a gear protrusion in the pocket, and wherein a portion of the hub is supported in the pocket and includes a hub protrusion, the gear protrusion drivingly engaging the hub protrusion.  
   
   
       19 . The drive mechanism of  claim 18 , wherein at least a portion of the elastic member is positioned between the gear protrusion and the hub protrusion.  
   
   
       20 . The drive mechanism of  claim 18 , wherein the elastic member includes a body, the first elastic element extending radially outwardly from the body between the gear protrusion and the hub protrusion.  
   
   
       21 . The drive mechanism of  claim 20 , wherein the second elastic member is positioned adjacent to the first elastic member and between the gear protrusion and the hub protrusion.  
   
   
       22 . The drive mechanism of  claim 18 , wherein the hub defines an aperture extending axially through the hub and providing access to the elastic member.  
   
   
       23 . The drive mechanism of  claim 18 , wherein the elastic member includes a body, the first elastic member being integrally formed with the body, the first elastic member and the body supporting the second elastic member in the pocket between the gear protrusion and the hub protrusion.  
   
   
       24 . A drive mechanism for a power tool, the power tool including a motor including a drive shaft and an output member adapted to support a tool element, the drive mechanism comprising: 
 a gear driven by the drive shaft for rotation about an axis, the gear defining a pocket and including a gear protrusion in the pocket;    a hub selectively driven by the gear for rotation about the axis, the hub being movable relative to the gear, the hub including a hub protrusion extending into the pocket and including a drive member offset from the axis and connected to the output member to drivingly connect the hub to the output member;    a drive arm connecting the drive member to the output member to convert rotation of the hub to reciprocation of the output member; and    an elastic member positioned in the pocket to allow relative movement between the gear and the hub, the elastic member including 
 a body,  
 a first elastic element extending radially outwardly from the body between the hub protrusion and the gear protrusion, and  
 a second elastic element integrally formed with the first elastic element.  
   
   
   
       25 . The drive mechanism of  claim 24 , wherein the first elastic member is compressible to absorb an impact within a first range, and wherein the second elastic member is compressible to absorb an impact within a second range.  
   
   
       26 . The drive mechanism of  claim 24 , wherein the first elastic element is formed of an elastomeric material.  
   
   
       27 . The drive mechanism of  claim 24 , wherein the second elastic element is a compression spring.  
   
   
       28 . The drive mechanism of  claim 24 , wherein the power tool is a reciprocating saw, wherein the output member is a spindle, wherein the tool element is a saw blade operable to cut a workpiece, and wherein together the first and second elastic elements absorb an impact resulting from a blade lock-up.  
   
   
       29 . A power tool comprising: 
 a housing;    an output member adapted to support a tool element;    a motor supported by the housing and including a drive shaft; and    a drive mechanism supported by the housing to drivingly connect the drive shaft and the output member, the drive mechanism including 
 a gear driven by the drive shaft for rotation about an axis,  
 a hub selectively driven by the gear for rotation about the axis, the hub being movable relative to the gear, the hub including a drive member offset from the axis to drivingly connect the hub to the output member, and  
 an elastic member positioned between the gear and the hub member to selectively transmit drive force from the gear to the hub, the elastic member being compressible to selectively allow relative movement between the gear and the hub, the elastic member including a first elastic element and a second elastic element.  
   
   
   
       30 . The power tool of  claim 29 , further comprising a drive arm connecting the drive member to the output member to convert rotation of the hub to reciprocation of the output member.  
   
   
       31 . The power tool of  claim 29 , wherein the power tool is a reciprocating saw, wherein the output member is a spindle, wherein the tool element is a saw blade operable to cut a workpiece, and wherein together the first and second elastic elements absorb an impact resulting from a blade lock-up.  
   
   
       32 . The power tool of  claim 29 , wherein the first elastic element is formed of an elastomeric material.  
   
   
       33 . The power tool of  claim 29 , wherein the second elastic element includes a compression spring.  
   
   
       34 . The power tool of  claim 29 , wherein the first elastic element is integrally formed with the second elastic element.  
   
   
       35 . The power tool of  claim 29 , wherein the gear defines a pocket and includes a gear protrusion in the pocket, and wherein a portion of the hub is supported in the pocket and includes a hub protrusion, the gear protrusion drivingly engaging the hub protrusion.  
   
   
       36 . The power tool of  claim 35 , wherein at least a portion of the elastic member is positioned between the gear protrusion and the hub protrusion.  
   
   
       37 . The power tool of  claim 35 , wherein the elastic member includes a body, the first elastic element extending radially outwardly from the body between the gear protrusion and the hub protrusion.  
   
   
       38 . The power tool of  claim 37 , wherein the second elastic member is positioned adjacent to the first elastic member and between the gear protrusion and the hub protrusion.  
   
   
       39 . The power tool of  claim 37 , wherein the hub defines an aperture extending axially through the hub and providing access to the elastic member.  
   
   
       40 . The power tool of  claim 29 , wherein the first elastic member is compressible to absorb an impact within a first range, and wherein the second elastic member is compressible to absorb an impact within a second range.  
   
   
       41 . A reciprocating saw comprising: 
 a housing;    a motor supported by the housing, the motor including a drive shaft;    a spindle movably supported by the housing, the spindle having an end adapted to support a saw blade, the saw blade being operable to cut a workpiece; and    a drive mechanism including 
 a gear driven by the drive shaft for rotation about an axis,  
 a hub selectively driven by the gear for rotation about the axis, the hub being movable relative to the gear, the hub including a drive member offset from the axis and connected to the output member to drivingly connect the hub to the output member and to convert rotation of the hub to reciprocation of the output member, and  
 an elastic member positioned between the gear and the hub to selectively transmit drive force from the gear to the hub, the elastic member including a first elastic element and a second elastic element, the first elastic element being compressible to absorb an impact within a first range and the second elastic element being compressible to absorb an impact within a second range.  
   
   
   
       42 . The reciprocating saw of  claim 41 , wherein together the first and second elastic elements absorb an impact resulting from a blade lock-up.  
   
   
       43 . The reciprocating saw of  claim 41 , wherein the elastic member is compressible to selectively allow relative movement between the gear and the hub.  
   
   
       44 . The reciprocating saw of  claim 41 , wherein the first elastic element is formed of an elastomeric material.  
   
   
       45 . The reciprocating saw of  claim 41 , wherein the second elastic element is a compression spring.  
   
   
       46 . The reciprocating saw of  claim 41 , wherein the first elastic element is integrally formed with the second elastic element.  
   
   
       47 . The reciprocating saw of  claim 41 , wherein the gear defines a pocket and includes a gear protrusion in the pocket, and wherein a portion of the hub is supported in the pocket and includes a hub protrusion, the gear protrusion drivingly engaging the hub protrusion.  
   
   
       48 . The reciprocating saw of  claim 47 , wherein at least a portion of the elastic member is positioned between the gear protrusion and the hub protrusion.  
   
   
       49 . The reciprocating saw of  claim 47 , wherein the elastic member includes a body, the first elastic element extending radially outwardly from the body between the gear protrusion and the hub protrusion.  
   
   
       50 . The reciprocating saw of  claim 48 , wherein the second elastic member is positioned adjacent to the first elastic member and between the gear protrusion and the hub protrusion.  
   
   
       51 . The reciprocating saw of  claim 47 , wherein the hub defines an aperture extending axially through the hub and providing access to the elastic member.  
   
   
       52 . The reciprocating saw of  claim 47 , wherein the elastic member includes a body, the first elastic member being integrally formed with the body, the first elastic member and the body supporting the second elastic member in the pocket between the gear protrusion and the hub protrusion.  
   
   
       53 . The reciprocating saw of  claim 41 , further comprising a drive arm connecting the drive member to the output member to convert rotation of the hub to reciprocation of the output member.