Patent ID: 9186784
Filing Date: 2015-11-17
Classification: B25B

Abstract:
1. A power wrench with a torque sensing unit, comprising a housing, a motor, an output shaft, and a planetary reduction gearing connecting the motor to the output shaft and including a stationary ring gear supported in the housing, wherein the torque sensing unit comprises a torque transferring element arranged to transfer reaction torque from the ring gear to the housing and carrying a strain measuring sensor arranged to generate electric signals in response to the magnitude of the transferred reaction torque, wherein: the torque transferring element comprises an annular body with an outer diameter equal to the inner diameter of the ring gear and having at an outer periphery a number of teeth matching and engaging teeth of the ring gear to thereby rotationally lock the torque transferring element to the ring gear, and said torque transferring element comprises a single reaction arm extending radially from the annular body and arranged to engage an abutment on the housing.