A power tool includes a housing, a motor positioned within the housing, an impulse assembly coupled to the motor to receive torque therefrom, the impulse assembly including a cylinder at least partially forming a chamber containing a hydraulic fluid, an anvil positioned at least partially within the chamber, and a hammer positioned at least partially within the chamber and engageable with the anvil for transferring rotational impacts to the anvil, the hammer including a through hole, and a valve configured to control flow of the hydraulic fluid through the through hole.

A power tool includes an electrostatic clutch assembly disposed between a motor and an end effector. A control circuit causes a first voltage to be applied to a first electrode of the electrostatic clutch assembly and a second voltage to be applied to a second electrode of the electrostatic clutch assembly, the first voltage being different from the second voltage, generating a first attractive force between the first and second electrodes, causing a shaft and a clutch housing to be coupled to each other when a torque on one of the shaft or the clutch housing is less than or equal to a first threshold value, and allowing the one of the shaft or the clutch housing to rotationally slip relative to the other of the shaft or the clutch housing when the torque on the one of the shaft or the clutch housing exceeds the first threshold value.

A power tool includes a housing, a motor positioned within the housing, an impulse assembly coupled to the motor to receive torque therefrom, the impulse assembly including a chamber containing a hydraulic fluid, an anvil positioned at least partially within the chamber, and a hammer configured to reciprocate within the chamber. The hammer is configured to displace the hydraulic fluid during reciprocation of the hammer such that the hydraulic fluid flows in the first direction when the hammer moves away from the anvil, and the hydraulic fluid flows in the second direction when the hammer moves toward the anvil. Flow resistance on the hydraulic fluid is different in the first direction and the second direction.

A power tool includes an electrostatic clutch assembly disposed between a motor and an end effector. A control circuit causes a first voltage to be applied to a first electrode of the electrostatic clutch assembly and a second voltage to be applied to a second electrode of the electrostatic clutch assembly, the first voltage being different from the second voltage, generating a first attractive force between the first and second electrodes, causing a shaft and a clutch housing to be coupled to each other when a torque on one of the shaft or the clutch housing is less than or equal to a first threshold value, and allowing the one of the shaft or the clutch housing to rotationally slip relative to the other of the shaft or the clutch housing when the torque on the one of the shaft or the clutch housing exceeds the first threshold value.

A power tool includes an electrostatic clutch assembly disposed between a motor and an end effector. A control circuit causes a first voltage to be applied to a first electrode of the electrostatic clutch assembly and a second voltage to be applied to a second electrode of the electrostatic clutch assembly, the first voltage being different from the second voltage, generating a first attractive force between the first and second electrodes, causing a shaft and a clutch housing to be coupled to each other when a torque on one of the shaft or the clutch housing is less than or equal to a first threshold value, and allowing the one of the shaft or the clutch housing to rotationally slip relative to the other of the shaft or the clutch housing when the torque on the one of the shaft or the clutch housing exceeds the first threshold value.

A power tool and method of controlling a motor of the power tool based on a determination of torque is provided. The method of determining torque uses the energy output by the drive mechanism and the angle of rotation of the output shaft to estimate torque. The energy is determined by subtracting efficiency losses (or gains) from a nominal energy of the drive mechanism in order to improve the torque estimation.