Patent ID: 9555525
Date: 2017-01-31
CPC Classifications: B25B

Claim:
1. A method for providing rotation speed control for impact type fastening tools comprising a presetting step and dynamic control step wherein the presetting step comprises setting a one of a plurality of working positions wherein the one of the plurality of working positions is set by a user operating a working position means, wherein each working position has a corresponding PWM signal, wherein different PWM signals have different duty cycles with one PWM signal having a maximum duty cycle being a maximum driving signal, and wherein each PWM signal is used to drive an electronic switch; using a main controller to identify the one of the plurality of positions set via use of the working position means; using the electronic switch to control a motor to rotate or stop, using a trigger switch to control a magnitude of current of the motor, and using a criterion pre-stored in the main controller for judging when to end efficient driving; and wherein, after the trigger switch energizes the motor, the dynamic control step comprises: (1) using the main controller to drive the electronic switch with a signal having a predetermined duty cycle to thereby drive the motor into rotation and, when a working position other than the maximum working position is selected, the duty cycle being a signal that is greater than a duty cycle of the driving signal of the selected working position; concurrently placing the main controller into a feedback signal detection state; and using a feedback means to collect actual physical quantities constituting a trigger and converting them into a feedback signal that can be received and processed by the main controller, and then proceeding to step (2); (2) using the main controller to judge the feedback signal received by it and when the feedback signal accords with the pre-stored criterion, proceeding to step (3) or, when the feedback signal does not accord with the pre-stored criterion, continuing to execute step (1); and (3) using a working position set in real time by the user by the main controller to cause the main controller to shift to use of a PWM signal corresponding to the working position to drive the electronic switch and thereby drive the motor until the trigger switch shuts off the power supply.