Self-Tightening Rotary Tool Holding System

Abstract

A tool holding system for a rotary power tool is configured to clamp around a working tool when the working tool is inserted in the tool holding system. The tool holding system includes a sleeve having a frustroconical inner surface portion, a collet having frustoconical outer surface portion complementary to the inner surface portion, a spring mount operably connected to a motor for rotation by the motor, and a spring. The spring includes a first end portion operably connected to the collet to bias the collet toward a first position whereat the outer surface portion engages the inner surface portion, and a second end portion rotationally fixed with respect to the spring mount.

What is claimed is: 
     
         1 . A rotary power tool comprising:
 a sleeve including a frustroconical inner surface portion;   a collet including frustoconical outer surface portion complementary to the inner surface portion;   a spring mount operably connected to a motor for rotation by the motor; and   a spring including a first end portion operably connected to the collet to bias the collet toward a first position whereat the outer surface portion engages the inner surface portion, and a second end portion rotationally fixed with respect to the spring mount.   
     
     
         2 . The rotary power tool of  claim 1  wherein:
 the rotary power tool is configured such that the motor rotates the spring mount in a counter-clockwise direction; 
 the spring is a left-hand wound spring; 
 the spring defines an inner diameter sized to receive a shank of a working tool therein; and 
 the inner diameter is aligned with an opening defined by the inner surface portion. 
 
     
     
         3 . The rotary power tool of  claim 1  further comprising:
 a one-way clutch rotationally fixed with respect to the spring mount and including an inner bore sized to receive a shank of a working tool. 
 
     
     
         4 . The rotary power tool of  claim 3  wherein the one-way clutch comprises:
 a hollow cylindrical member (i) rotationally fixed with respect to the output shaft of the power tool, (ii) defining a shank receiving opening extending longitudinally through the hollow cylindrical member and configured to receive the shank of the working tool, and (iii) including a plurality of indentations defined in an inner surface of the hollow cylindrical member; 
 a plurality of rolling members; and 
 a plurality of biasing members, each respective biasing member of the plurality of biasing members braced in a respective indentation of the plurality of indentations and configured to exert a biasing force urging a respective rolling member of the plurality of rolling members toward the shank receiving opening, such that rotation of the output shaft and the hollow cylindrical member in a first rotational direction causes each of the plurality of rolling members to be wedged between a surface of the respective indentation and the shank to clamp the shank in the hollow cylindrical member. 
 
     
     
         5 . A tool holding system comprising:
 a first cage member including a first plurality of elongated slots, each of the first plurality of elongated slots having a first end portion which opens to a first shank receiving opening defined by the first cage member, and a second end portion which does not open to the first shank receiving opening;   a plurality of roller members, each roller member of the plurality of roller members movably positioned in a respective one of the first plurality of elongated slots; and   a roller carriage including a carriage opening aligned with the first shank receiving opening, and a plurality of generally cylindrical passages, each of the plurality of generally cylindrical passages (i) substantially parallel to the central axis, (ii) receiving a portion of a respective one of the plurality of roller members, and (iii) configured to prevent the respective roller member from moving circumferentially relative to the roller carriage while permitting the respective roller member to move radially relative to the roller carriage within a predetermined range.   
     
     
         6 . The tool holding system of  claim 6  wherein the roller carriage is rotationally biased such that each of the plurality of roller members is biased toward the first end portion of the respective first plurality of elongated slots. 
     
     
         7 . The tool holding system of  claim 5  further comprising:
 a second cage member including a second plurality of elongated slots, each of the second plurality of elongated slots having a third end portion which opens to a second shank receiving opening defined by the second cage member, and a fourth end portion which does not open to the second shank receiving opening, wherein each of the second plurality of elongated slots is generally aligned axially with a respective one of the first plurality of elongated slots. 
 
     
     
         8 . A rotary power tool comprising:
 a first one-way clutch rotationally fixed with respect to an output shaft of a rotary power tool and defining a first shank receiving opening; and   an alignment assembly including a second shank receiving opening aligned with the first tool receiving opening, the alignment assembly configured to align a shank of a working tool received within the first shank receiving opening and the second shank receiving opening, and to generate a damping force on the received shank.   
     
     
         9 . The rotary power tool of  claim 8 , wherein the alignment assembly comprises:
 a sleeve including a frustroconical inner surface portion;   a collet including frustoconical outer surface portion complementary to the inner surface portion; and   a spring including a first end portion operably connected to the collet to bias the collet toward a first position whereat the outer surface portion engages the inner surface portion.   
     
     
         10 . The rotary power tool of  claim 9  wherein the first one-way clutch comprises:
 a hollow cylindrical member (i) rotationally fixed with respect to the output shaft of the power tool, (ii) defining a shank receiving opening extending longitudinally through the hollow cylindrical member and configured to receive the shank of the working tool, and (iii) including a plurality of indentations defined in an inner surface of the hollow cylindrical member; 
 a plurality of rolling members; and 
 a plurality of biasing members, each respective biasing member of the plurality of biasing braced in a respective indentation of the plurality of indentations and configured to exert a biasing force urging a respective rolling member of the plurality of rolling members toward the shank receiving opening, such that rotation of the output shaft and the hollow cylindrical member in a first rotational direction causes each of the plurality of rolling members to be wedged between a surface of the respective indentation and the shank to clamp the working tool in the hollow cylindrical member. 
 
     
     
         11 . The rotary power tool of  claim 8 , wherein the alignment assembly comprises:
 a rubber alignment ring.   
     
     
         12 . The rotary power tool of  claim 9  further comprising:
 a second one-way clutch rotationally fixed with respect to the output shaft of the rotary power tool and defining a third shank receiving opening aligned with the first shank receiving opening, wherein the first one-way clutch is configured to clamp the shank when the output shaft rotates in a first direction, and the second one-way clutch is configured to clamp the shank when the output shaft rotates in a second direction opposite to the first direction. 
 
     
     
         13 . The rotary power tool of  claim 12  wherein the second one-way clutch comprises:
 a hollow cylindrical member (i) rotationally fixed with respect to the output shaft of the power tool, (ii) defining a shank receiving opening extending longitudinally through the hollow cylindrical member and configured to receive the shank of the working tool, and (iii) including a plurality of indentations defined in an inner surface of the hollow cylindrical member; 
 a plurality of rolling members; and 
 a plurality of biasing members, each respective biasing member of the plurality of biasing braced in a respective indentation of the plurality of indentations and configured to exert a biasing force urging a respective rolling member of the plurality of rolling members toward the shank receiving opening, such that rotation of the output shaft and the hollow cylindrical member in a first rotational direction causes each of the plurality of rolling members to be wedged between a surface of the respective indentation and the shank to clamp the working tool in the hollow cylindrical member. 
 
     
     
         14 . A rotary power tool comprising:
 a first collar rotationally fixed with respect to an output shaft of a power tool and including a first shank receiving opening having a longitudinal axis;   a second collar movable with respect to the output shaft and including at least one inclined outer surface; and   at least one lever pivotably connected to the first collar and including a first end portion configured to engage the at least one inclined outer surface, and a cam located at a second end portion, the cam extending into the first shank receiving opening such that upon rotation of the output shaft in a first rotational direction, the at least one inclined outer surface is forced against the first end portion thereby forcing the cam toward the axis.   
     
     
         15 . The rotary power tool of  claim 14  wherein:
 the at least one lever comprises a plurality of levers; 
 the at least one inclined outer surface comprises a plurality of cam regions, each cam region associated with a respective one of the plurality of levers, each of the cam regions extending from a first radial location to a second radial location radially outward from the first radial location. 
 
     
     
         16 . The rotary power tool of  claim 15  wherein:
 each of the plurality of levers includes a beveled side surface in opposition to the associated cam region. 
 
     
     
         17 . The rotary power tool of  claim 16  further comprising:
 a biasing member configured to rotationally bias the second collar such that the cam regions are biased toward the associated opposing beveled side surface. 
 
     
     
         18 . The rotary power tool of  claim 14 , further comprising a third collar, wherein:
 the third collar is rotatable about the longitudinal axis with respect to the output shaft;   the second collar is rotatably fixed about the longitudinal axis with respect to the output shaft;   the third collar includes at least one first cam region; and   the second collar includes at least one second cam region, the at least one second cam region in opposition to the at least one first cam region, such that rotation of the third collar about the longitudinal axis in a first direction forces the at least one first cam region against the at least one second cam region, thereby biasing the third collar along the longitudinal axis.   
     
     
         19 . The rotary power tool of  claim 18 , further comprising:
 a biasing member configured to rotationally bias the third collar in the first direction.   
     
     
         20 . The rotary power tool of  claim 19 , wherein:
 the at least one first cam region comprises a threaded portion of the third collar; and   the at least one second cam region comprises a threaded portion of the second collar.