Control module for flywheel operated hand tool

Abstract

A control module advantageously reduces cost and enhances reliability, design flexibility, ease of assembly, and performance of a flywheel operated hand tool. The control module includes a thin film printed circuit with non-contact speed sensing of a flywheel to more accurately set the target speed and control transfer kinetic energy thereof to a fastener, achieving a desired depth regardless of variations in component performance and battery voltage. The printed circuit also includes long service life thin film switches for responding to trigger and safety inputs. Furthermore, the control module responds to a user speed selection and to preset speed selection ranges to reconfigure the controls as appropriate to constraints of a fastener drive assembly and to user preferences.

What is claimed is:  
     
         1 . A control module for an electrically power hand tool having a rotary member; comprising: 
 a speed adjustment circuit;    a speed sensor operable to sense a rotary speed of the rotary member; and    a controller responsive to the speed adjustment circuit to set a speed target and operably configured to command the rotary member in response to a comparison of the sensed rotary speed and the speed target.    
     
     
         2 . The control module of  claim 1 , wherein the speed sensor comprises a noncontact transducer.  
     
     
         3 . The control module of  claim 1 , wherein the rotary member includes magnetic poles, the speed sensor comprises an inductive pickup operable to sense the magnetic poles on the rotary member.  
     
     
         4 . The control module of  claim 1 , further comprising: 
 a mechanical control for receiving a user input for operating the hand tool; and a thin film switch in physical communication with the mechanical control and in electrical communication with the controller.    
     
     
         5 . A method of controlling a electrically powered rotary member of a hand tool, comprising: 
 in respone to receiving a user command, accelerating the rotary member;    sensing a rotary speed of the rotary member;    decelerating the rotary member in response the rotary speed of the rotary member exceeding a speed target.    
     
     
         6 . The method of  claim 5 , wherein the hand tool comprises a fastener driving tool having a safety switch and a trigger switch, the receiving a user command comprises: 
 receiving a safety signal from the safety switch indicating a nose assembly of the tool is against a workpiece;    accessing a safety time-out value;    timing a duration of depression of the safety signal;    activating the tool to drive a fastener in response to receiving a trigger signal from the trigger switch before the timed duration of the safety signal exceeds the safety time-out value.    
     
     
         7 . A portable hand tool, comprising: 
 an electric motor;    a rotary member turned by the electric motor;    a speed adjustment circuit;    a speed sensor operable to sense a rotary speed of the rotary member; and    a controller responsive to the speed adjustment circuit to set a speed target and operably configured to command electric motor to turn the rotary member in response to a comparison of the sensed rotary speed and the speed target.    
     
     
         8 . An electric powered hand tool, comprising: 
 an electric motive device;    at least one mechanical control positioned by a user;    a controller operably configured to command the electric motive device in response to an electrical command; and    a thin film switch in mechanical communication with the mechanical control and in electrical communication with the controller and operable to provide an electrical command in response to positioning of the mechanical control.