Patent ID: 11872680
Assignee: BLACK & DECKER, INC.
Field: Machine tools (Mechanical engineering)
Classification: CPC B | IPC B

Claim 18:
19. An impact power tool comprising:
a housing;
a motor disposed in the housing and having a motor output shaft;
a transmission having an input member rotatably drivable by rotation of the motor output shaft and a transmission output shaft;
a rotary impact assembly including a cam shaft received partially or fully over the transmission output shaft, a hammer coupled to the cam shaft and able to move axially and rotatably relative to the cam shaft; an anvil rotatable about the axis, and a spring biasing the hammer toward the anvil;
a tool output shaft partially or fully received in the housing and rotatable by rotation of the anvil; and
a coupler removably coupling the cam shaft to the transmission output shaft,
wherein when torque on the tool output shaft is at or below a first threshold, the coupler non-rotatably couples the transmission output shaft to the cam shaft and the hammer continuously engages the anvil so that the transmission shaft, the cam shaft, the hammer and the anvil rotate together to transmit torque to the tool output shaft without impacts,
wherein when torque on the tool output shaft is above the first threshold, the coupler non-rotatably couples the transmission output shaft to the cam shaft and the hammer moves along the cam shaft away from the anvil at least a first distance and applies intermittent rotary impacts to the anvil and the tool output shaft, and
wherein when torque above a second threshold greater than the first threshold is applied to the output shaft, the hammer moves along the cam shaft away from the anvil by at least a second distance that is greater than the first distance and causes the coupler to decouple the transmission output shaft from the cam shaft, interrupting torque transmission to the tool output shaft.