Nanjing Chervon Industry Co., Ltd.

Guang Li

Yanqing Xu

Yongkang Wu

Yang Li

Hongtao Ke

Shuai Chen

Longxiang Liu

Zhiwei Feng

Aihua Xie

Shuang Li

A power tool includes a motor, a switch, a driver circuit, an operating element, and a controller. The motor includes a multi-phase winding. The driver circuit has multiple power elements and is configured to change a rotational state of the motor. The operating element has a first operating state and a second operating state, where a strength of an effective magnetic field of the multi-phase winding when the operating element is in the first operating state is less than a strength of an effective magnetic field of the multi-phase winding when the operating element is in the second operating state. The controller is configured to control conduction manners of the multiple power elements in the driver circuit according to an operating state of the operating element, so as to adjust the strength of the effective magnetic field of the multi-phase winding and change the rotational state of the motor.

Power tool

An impact tool includes an output shaft for outputting torque, where the tightening torque of the output shaft to a workpiece is greater than or equal to 700 foot-pounds; and an impact assembly that provides an impact force to the output shaft. A main shaft ball groove includes a first ball groove that extends spirally about a main shaft axis and is concave on an outer surface and a second ball groove that extends spirally about the main shaft axis and is concave on the outer surface. An impact ball groove includes a third ball groove that mates with the first ball groove to accommodate the rolling ball and a fourth ball groove that mates with the second ball groove to accommodate the rolling ball. The included angle α between the first ball groove and the second ball groove is less than the included angle β between the third ball groove and the fourth ball groove.

Impact tool

A power tool includes a motor, a speed regulation mechanism, a driver circuit, and a control module. The motor includes a stator winding and a rotor. The speed regulation mechanism is at least used for setting a target rotational speed of the motor. The driver circuit is used for delivering electrical energy provided by a power supply device from a direct current bus to the motor, where the driver circuit includes multiple electronic switches connected between the power supply device and the motor. The control module is configured to calculate a voltage vector according to a measured rotational speed of the motor, a phase current of the stator winding, and the target rotational speed and overmodulate the voltage vector to output a pulse-width modulation (PWM) signal to the driver circuit. A per-unit value of an amplitude of the voltage vector ranges from 0 to 1.15.

A power tool includes a housing, an electric motor, a driver circuit, a speed detection device, and a control device. The driver circuit is electrically connected to the electric motor to drive the electric motor to operate. The speed detection device is configured to acquire a rotational speed of the electric motor. The control device is connected to the speed detection device and the driver circuit and outputs a control signal to the driver circuit to control rotation of the electric motor. The control device is configured to acquire the rotational speed of the electric motor when the electric motor is in a start-up stage, obtain a rotational speed variation of the electric motor within a preset time based on the rotational speed of the electric motor, and turn off the electric motor when the rotational speed variation is less than a rotational speed variation threshold.

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Nanjing, China

Guang Li