Patent ID: 9555527
Date: 2017-01-31
CPC Classifications: B25B,B25F

Claim:
1. A method for controlling torque output of a DC electric tool, comprising: presetting on the DC electric tool a plurality of torque levels and a plurality of voltage ranges corresponding to the plurality of torque levels; detecting a current output voltage of a battery used to power the DC electric tool and determining one of the plurality of voltage ranges in which the current output voltage of the battery is located; determining whether the one of the plurality of voltage ranges in which the current output voltage of the battery is located matches a selected one of the plurality of torque levels; when it is determined that the one of the plurality of voltage ranges in which the current output voltage of the battery is located does not match a selected one of the plurality of torque levels providing a warning that a torque output of the DC electric tool cannot reach the selected one of the plurality of torque levels and further calculating and displaying a highest one of the plurality of torque levels which the current output voltage of the battery is capable of providing; and when it is determined that the one of the plurality of voltage ranges in which the current output voltage of the battery is located does match a selected one of the plurality of torque levels, calculating a current actual torque output value and keeping a PWM value constant for maintaining the current actual torque output value when the current actual torque output value conforms to the one of the plurality of selected torque levels or increasing the PWM value for compensation when the current actual torque output value does not conform to the selected one of the plurality of torque levels so that the current actual torque output value is capable of reaching the preset value corresponding to the selected one of the plurality torque levels.