Power tool with torque clutch

Abstract

A power tool with a multi-speed transmission and a switch mechanism for shifting the transmission between a plurality of different speed ratios. The switch mechanism includes a single switch member that is slidably mounted on the housing. The power tool further comprises a clutch having a clutch profile that is coupled to a ring gear of the transmission. In some examples, the power tool further comprises a clutch that is configured to interact with a first stage of the transmission.

1 . A power tool comprising:
 a housing;   a motor received in the housing and having an output shaft;   an output spindle;   a transmission having a plurality of planetary transmission stages comprising a first planetary transmission stage, at least one intermediate stage and an output stage, the first planetary stage receiving rotary power directly from the output shaft of the motor, the first planetary stage having a ring gear and outputting rotary power to the at least one intermediate stage, the at least one intermediate stage outputting power to the output stage, the output stage having an output member that is coupled to output spindle, the transmission being operable in at least three different speed ratios;   a clutch assembly that comprises a clutch profile and an engagement assembly, the clutch profile being coupled to the ring gear, the engagement assembly including a follower and an adjustment collar, the adjustment collar being movable to change a magnitude of a biasing force exerted by the follower member onto the clutch profile, the follower assembly cooperating with the clutch profile to permit continuous rotation of the ring gear of the first planetary transmission stage relative to the housing when the magnitude of the intermediate output torque exceeds a selected maximum torque to thereby limit rotary power that is output through the output member to a selected maximum tool torque, the follower assembly also cooperating with the clutch profile to inhibit rotation of the first ring gear relative to the housing when the magnitude of the intermediate torque does not exceed the selected clutch torque; and   a switch mechanism for shifting the transmission between the at least three different speed ratios, the switch mechanism comprising a single switch member that is slidably mounted on the housing for movement between a first switch position, a second switch position and a third switch position, wherein the transmission operates in a first speed ratio when the switch member is in the first position, the transmission operates in a second speed ratio when the switch member is in the second position and the transmission operates in a third speed ratio when the switch member is in the third position.   
     
     
         2 . The power tool of  claim 1 , wherein the switch member is rotatably mounted on the housing. 
     
     
         3 . The power tool of  claim 2 , wherein the switch member is rotatably about an axis that is coincident with a rotational axis of the output spindle and the output shaft. 
     
     
         4 . The power tool of  claim 1 , wherein the clutch profile faces the at least one intermediate stage. 
     
     
         5 . The power tool of  claim 1 , wherein the ring gear has opposite axial ends and wherein the clutch profile is located on the ring gear between the opposite axial ends of the ring gear. 
     
     
         6 . The power tool of  claim 5 , wherein the clutch profile is defined by an annular member that is received onto an annular flange formed about the ring gear. 
     
     
         7 . The power tool of  claim 6 , wherein a cushioning member is disposed between the annular member and the annular flange. 
     
     
         8 . The power tool of  claim 1 , wherein the switch mechanism further comprises a cam and a pair of followers, the cam being mounted to the single switch member for rotation therewith, the cam defining a first set of cam tracks and a second set of cam tracks, each of the followers being coupled to a corresponding movable element in the transmission, the first and second cam tracks being configured to coordinate movement of the followers in a predetermined manner as the single switch member is moved between the first, second and third switch positions. 
     
     
         9 . A power tool comprising:
 a housing;   a motor received in the housing and having an output shaft;   an output spindle;   a transmission having a plurality of planetary transmission stages comprising a first planetary transmission stage and an output stage, the first planetary stage receiving rotary power directly from the output shaft of the motor, the output stage having an output member that is coupled to output spindle, the transmission being operable in a plurality of different speed ratios;   a clutch assembly that comprises a clutch profile and an engagement assembly, the clutch profile being coupled to the ring gear, the engagement assembly including a follower and an adjustment collar, the adjustment collar being movable to change a magnitude of a biasing force exerted by the follower member onto the clutch profile, the follower assembly cooperating with the clutch profile to permit continuous rotation of the ring gear of the first planetary transmission stage relative to the housing when the magnitude of the intermediate output torque exceeds a selected maximum torque to thereby limit rotary power that is output through the output member to a selected maximum tool torque, the follower assembly also cooperating with the clutch profile to inhibit rotation of the first ring gear relative to the housing when the magnitude of the intermediate torque does not exceed the selected clutch torque; and   a switch mechanism for shifting the transmission between the different speed ratios, the switch mechanism comprising a single switch member that is slidably mounted on the housing.   
     
     
         10 . The power tool of  claim 9 , wherein the switch member is rotatably mounted on the housing. 
     
     
         11 . The power tool of  claim 10 , wherein the switch member is rotatably about an axis that is coincident with a rotational axis of the output spindle and the output shaft. 
     
     
         12 . The power tool of  claim 9 , wherein the clutch profile faces toward the output stage. 
     
     
         13 . The power tool of  claim 9 , wherein the ring gear has opposite axial ends and wherein the clutch profile is located on the ring gear between the opposite axial ends of the ring gear. 
     
     
         14 . The power tool of  claim 13 , wherein the clutch profile is defined by an annular member that is received onto an annular flange formed about the ring gear. 
     
     
         15 . The power tool of  claim 14 , wherein a cushioning member is disposed between the annular member and the annular flange. 
     
     
         16 . The power tool of  claim 9 , wherein the switch mechanism further comprises a cam and a follower, the cam being mounted to the single switch member for rotation therewith, the cam defining a set of cam tracks, the follower being coupled to a movable element in the transmission, the set of cam tracks being configured to coordinate movement of the follower in a predetermined manner as the single switch member is moved on the housing. 
     
     
         17 . The power tool of  claim 9 , wherein the transmission is operable in at least three different speed ratios. 
     
     
         18 . A power tool comprising:
 a housing defining a motor cavity and a handle, the motor cavity defining a longitudinal axis of the power tool, the housing having first and second axial ends, the handle being disposed between the first and second ends such that the handle is axially offset from the first end and axially offset from the second end;   a motor received in the motor cavity and having an output shaft;   a planetary transmission having a plurality of stages including a first stage, at least one intermediate stage and an output stage, the first planetary stage receiving rotary power directly from the output shaft of the motor, the first planetary stage outputting rotary power to the at least one intermediate stage, the at least one intermediate stage outputting power to the output stage, the output stage having an output member that is coupled to output spindle, the transmission being operable in at least three different speed ratios, wherein one of the plurality of stages has a ring gear;   a clutch assembly that comprises a clutch profile and an engagement assembly, the clutch profile being coupled to the ring gear, the engagement assembly including a follower and an adjustment collar, the adjustment collar being movable to change a magnitude of a biasing force exerted by the follower member onto the clutch profile; and   a switch mechanism for shifting the transmission between the at least three different speed ratios, the switch mechanism comprising a single switch member that is slidably mounted on the housing for movement between a first switch position, a second switch position and a third switch position, wherein the transmission operates in a first speed ratio when the switch member is in the first position, the transmission operates in a second speed ratio when the switch member is in the second position and the transmission operates in a third speed ratio when the switch member is in the third position.   
     
     
         19 . The power tool of  claim 18 , wherein the ring gear is in the first planetary stage. 
     
     
         20 . The power tool of  claim 18 , wherein the switch mechanism further comprises a cam and a follower, the cam being mounted to the single switch member for rotation therewith, the cam defining a set of cam tracks, the follower being coupled to a movable element in the transmission, the set of cam tracks being configured to coordinate movement of the follower in a predetermined manner as the single switch member is moved on the housing.