The present invention relates to switching element protection of a BLDC motor, such as used with a power tool. The present invention checks each switching element of a power stage individually for a short circuit when a trigger of the tool is actuated. Each switching element is turned ON for a period of time (such as 1-5 microseconds, for example), current flowing through the half-bridge or the full power stage is measured, and that switching element is turned OFF. When the current is greater than or equal to a threshold (such as 5 A, for example), the controller stops and indicates a fault condition. By testing each switching element in order, the controller is able to determine whether the shorted switching element is the opposite one in the half-bridge being tested.

The present invention relates to a method of commutation control of a BLDC motor. The method uses a controller to control the BLDC motor using a modified six-step commutation. The method adds six intermediate steps that overlap the six-step commutation. Each of the six steps overlap with preceding and following steps, resulting in six additional intermediate steps in which all three phases are active. By doubling the number of steps, current and torque will vary less over time compared with current solutions without increasing the size or changing the design of the motor.

Overcurrent protection of an electrically powered, motorized device, such as a power tool, wherein the tool includes a tool housing, an output assembly, a trigger, an electrical safety device, a motor, an indicator, a controller, and a power source. The electrical safety device, for example a fuse, is disposed in series with a power connection from the power source to the controller. The controller measures current passing through the electrical safety device in time intervals when the trigger is actuated. The controller determines accumulated thermal energy passing through the electrical safety device, and compares the accumulated thermal energy to a threshold. If the accumulated thermal energy exceeds the threshold, the controller ceases or discontinues to allow power to be provided to the motor from the power source, thereby shutting off the motor. The controller may also activate the indicator to indicate a fault to the user.

A power tool comprises a housing defining a grip portion, a motor having a motor drive shaft, a drive assembly including a crankshaft configured to receive torque from the motor drive shaft, an output assembly having an output member configured to receive torque from the crankshaft, a bearing rotatably supporting the crankshaft, a retainer configured to prevent translation of the bearing along the crankshaft past the retainer, and a transducer assembly disposed between the grip portion and the output member to measure the amount of torque applied through the output member.

A wrench including a tool head including a tool output member. The wrench also includes a motor configured to selectively drive the output member and a battery assembly. The battery assembly includes a battery cell and the battery cell provides power to the motor. A support tube surrounds at least a portion of the motor and a portion of the battery assembly. A handle surrounds the support tube.

Disclosed are devices, systems and methods for improving medical instruments and related tools, such as a ratcheting module that can be attached to various surgical instruments used during surgery.

An electric ratchet wrench includes a body and a driving member rotatably mounted in the body and is rotatable about an axis. A ring gear is rotatably mounted to and moveable relative to the driving member, and the ring gear is rotatable relative to the driving member about a center axis of the ring gear. A power device is received in the body. A transmission shaft is rotatably mounted to the body. The transmission shaft has a end connected to the power device, and another end configured to switch between a meshing state meshed with the ring gear and a disengagement state disengaging from the ring gear. An elastic device biases the ring gear causing the center axis of the ring gear being inclined relative to the axis in the disengagement state and being parallel with the axis in the meshing state.

A ratchet wrench with electric assistance includes a wrench body, a ratchet device, a pawl device, and a switch device. The switch device is configured for optionally gearing the pawl device with the ratchet device, so that the ratchet wrench is operated in a clockwise or counterclockwise direction. During the directional changing process, the switch device optionally engages the first gear and the second gear with the transmission gear of the power device, such that the power device transmits the power to the ratchet device for controlling the clockwise or counterclockwise rotation of the ratchet device, realizing the ratchet wrench with an electric assistance function.

A powered ratchet tool including a housing and a drive mechanism for driving an output member. The drive mechanism includes a yoke through which the output member extends. The ratchet tool further comprises a first selective pawl, a second selective pawl, and a non-selective pawl in the yoke that are biased toward an outer toothed surface of the output member and blocking member. The outer toothed surface includes first and second selectively-toothed sections. When the first selectively-toothed section and second selectively-toothed sections are rotationally aligned with the with the first selective pawl and the second selective pawl, the first and second selective pawls are incapable of transferring torque to the output member. The blocking member moves between an operating position, wherein the non-selective pawl is engaged with the outer toothed surface, and a home position, wherein the blocking member inhibits the non-selective pawl from engaging with the outer toothed surface.

An electric ratchet wrench as one example of the ratchet wrench includes an electric motor, a holder that rotatably holds a socket via a one-way clutch mechanism, and a spindle configured to convert a driving force from the motor into a reciprocating rotation motion of the holder. A space is provided between the socket and the holder. The space includes large interval portions and small interval portions. The small interval portions are adjacent to the large interval portions in a rotation direction (lock direction) of the socket and have distances smaller than distances of the large interval portions. Additionally, the one-way clutch mechanism includes columnar locking pins disposed between the spaces and have a diameter with a size equal to or less than the distances of the large interval portions and exceeding the distances of the small interval portions.