Impact Screwdriver

摘要

An impact screwdriver having a housing is disclosed comprising an impact mechanism including a hammer interacting with an anvil for driving a tool, wherein the hammer is arranged on a drive shaft so as to be axially movable and preloaded in the axial direction, and wherein the hammer is driven by the drive shaft via a driver and is preloaded counter to the force of a spring element in order to trip and to transmit a rotary impulse to the anvil when a particular rotation angle is exceeded, wherein the hammer and the anvil are mounted in a manner electrically insulated from one another and are connected to a voltage source, and wherein a sensor is provided for monitoring a current flow between the hammer and anvil during contact thereof for determining a contact duration between the hammer and the anvil.

主权项

1. An impact screwdriver comprising:
a housing; an impact mechanism received within said housing, wherein said impact mechanism comprises: an output shaft coupled to a tool receptacle; an anvil coupled to said output shaft; a drive shaft for driving said impact mechanism; a hammer arranged on said drive shaft axially movable electrically insulated from said anvil; a spring element arranged for preloading said hammer in an axial direction towards said anvil; a driver for driving said hammer towards said anvil; a speed sensor arranged for sensing a rotational speed of said drive shaft; and an electrical sensor being arranged for monitoring a current flow between said hammer and said anvil during contact between said hammer and said anvil for determining a duration of said contact; a voltage source being coupled to said hammer and said anvil; and a controller being coupled to said speed sensor and to said electrical sensor for measuring the rotational speed of said drive shaft and for determining an integrated contact duration between said hammer and said anvil for calculating a tightening torque of a screw connection to be tightened based on the rotational speed of said drive shaft and on the integrated contact duration between said hammer and said anvil; wherein said hammer is driven by said drive shaft via said driver and is preloaded counter to the force of said spring element for tripping against said anvil and for transmitting a rotary impulse onto said anvil, when a particular angle of rotation is exceeded; and wherein said controller is configured for switching off said impact mechanism upon reaching a predetermined tightening torque.