US 12,220,834 B2
Chain saw
Jinbiao Zhao, Nanjing (CN); and Hongwei Wang, Nanjing (CN)
Assigned to Nanjing Chervon Industry Co., Ltd., Nanjing (CN)
Filed by Nanjing Chervon Industry Co., Ltd., Nanjing (CN)
Filed on May 24, 2021, as Appl. No. 17/328,565.
Application 17/328,565 is a continuation of application No. PCT/CN2019/121639, filed on Nov. 28, 2019.
Claims priority of application No. 201811433127.7 (CN), filed on Nov. 28, 2018; and application No. 201811433129.6 (CN), filed on Nov. 28, 2018.
Prior Publication US 2021/0276217 A1, Sep. 9, 2021
Int. Cl. B27B 17/08 (2006.01); B25F 5/00 (2006.01); B27B 17/02 (2006.01); H02P 3/22 (2006.01); H02P 6/24 (2006.01)
CPC B27B 17/083 (2013.01) [B25F 5/00 (2013.01); B27B 17/02 (2013.01); H02P 3/22 (2013.01); H02P 6/24 (2013.01)] 17 Claims
OG exemplary drawing
 
1. A chain saw, comprising:
a body;
a working part mounted to the body, the working part comprising a guide bar and a saw chain;
a brushless motor mounted within the body and coupled to the working part to drive the working part to work, the brushless motor having a driving mode and an emergency, braking mode, the brushless motor comprising a rotor;
a power supply device mountable to the body and electrically coupleable to the brushless motor to provide an electrical energy for the brushless motor;
a drive circuit connected to the power supply device and the brushless motor, the drive circuit providing an operating electrical current to the brushless motor in the driving mode to operate the working part, and the drive circuit providing a braking electrical current to the brushless motor in the braking mode to stop movement of the working part;
a controller connected to the drive circuit for controlling the drive circuit; and
a motion detection device coupled to at least one of the body or the working part for detecting a motion of the body or the working part in an at least one direction;
wherein the controller is configured to control the drive circuit to make the brushless motor enter the braking mode when an amount of the motion of the body or the working part in the at least one direction exceeds a predetermined threshold, and
wherein the controller is configured to control the drive circuit to make the brushless motor enter the braking mode when: (a) a value of an angular velocity at which the body or the working part rotates in the at least one direction is greater than a first predetermined angular velocity threshold and less than a second predetermined angular velocity threshold; and (b) a value of an angular displacement at which the body or the working part rotates in the at least one direction is greater than a predetermined angular displacement threshold.