AUTOMATIC TRANSMISSION FOR POWER TOOLS

摘要

An automatic gearshift device for a power tool includes a speed reduction mechanism that decelerates and transmits a rotary power of a motor, a ring gear that slides and moves to switch a speed reduction ratio, a cam member that moves the ring gear, a rotation body rotated in cooperation with the cam member, a position detector that detects the position of the ring gear, and a controller that controls the driving of the gearshift motor based on the value generated by the position detector. An adjustment gear forming the rotation body includes a slot used as a positioning mark at a predetermined location in the rotating direction. When the slot of the adjustment gear is aligned with a predetermined device side positioning reference, the rotation body is positioned in an initial position in a relative positional relationship with the ring gear.

主权项

1. An automatic gearshift device for a power tool comprising:
a speed reduction mechanism including a gear member, wherein the speed reduction mechanism decelerates and transmits a rotary power of a driving source; a switching member that slides and moves to an engagement position where the switching member engages with the gear member of the speed reduction mechanism to switch a speed reduction ratio of the speed reduction mechanism; a gearshift motor; a cam member driven and rotated by the gearshift motor to move the switching member to the engagement position; a rotation body rotated in cooperation with the cam member when driven by the gearshift motor, wherein the rotation body includes a positioning mark set at a predetermined position in a rotating direction of the rotation body, and the rotation body is positioned in an initial position in a predetermined relative positional relationship with the switching member; a position detector that detects movement of the switching member to the engagement position and generates a value indicating that the switching member has moved to the engagement position when the rotation body is rotated from the initial position by a predetermined rotation angle; and a controller that controls the driving of the gearshift motor based on the value generated by the position detector, wherein the rotation body is located at the initial position when the positioning mark is aligned with a predetermined device side positioning reference.