Actuation mechanism for use with an ultrasonic surgical instrument

Abstract

An ultrasonic clamp coagulator assembly that is configured to permit selective cutting, coagulation and clamping of tissue during surgical procedures. An elongated portion of the instrument can be configured for endoscopic applications and has an outside diameter of less than 6 mm. The construction includes a clamping mechanism, including a clamp arm pivotally mounted at the distal portion of the instrument, which is specifically configured to create a desired level of tissue clamping forces, exceeding 4 pounds when the trigger is fully closed. The clamping mechanism includes a force-limiting mechanism that effectively smooths out abusive tissue forces.

1 - 13 . (canceled) 
     
     
         14 . An ultrasonic surgical instrument, comprising:
 an end effector, comprising:
 an ultrasonic blade; and 
 a clamp arm pivotable relative to the ultrasonic blade between an open position and a closed position; 
   a shaft assembly extending proximally from the end effector, wherein the shaft assembly comprises:
 an outer tube; and 
 an inner tube movable relative to the outer tube, wherein the inner tube is operably coupled to the clamp arm, wherein movement of the inner tube is configured to pivot the clamp arm between the open position and the closed position, and wherein the inner tube is configured to apply a closure force to the clamp arm; 
   an ultrasonic waveguide extending proximally from the ultrasonic blade through the shaft assembly;   a housing extending proximally from the shaft assembly, wherein the housing comprises a trigger, and wherein the inner tube is moveable relative to the outer tube based on movement of the trigger; and   a force limiting mechanism operably coupled to the trigger and the inner tube, wherein the force limiting mechanism is configured to limit the closure force the inner tube can apply to the clamp arm.   
     
     
         15 . The ultrasonic surgical instrument of  claim 14 , wherein proximal movement of the inner tube pivots the clamp arm towards the closed position. 
     
     
         16 . The ultrasonic surgical instrument of  claim 14 , wherein distal movement of the inner tube pivots the clamp arm towards the open position. 
     
     
         17 . The ultrasonic surgical instrument of  claim 14 , wherein the trigger is moveable relative to the housing between a first position, a second position, and a third position, and wherein the force limiting mechanism is configured to exclusively limit the closure force the inner tube can apply to the clamp arm based on movement of the trigger between the second position to the third position. 
     
     
         18 . The ultrasonic surgical instrument of  claim 14 , wherein the force limiting mechanism comprises a proximal spring and a distal spring. 
     
     
         19 . The ultrasonic surgical instrument of  claim 18 , wherein the distal spring is operably coupled to the inner tube, wherein the distal spring is configured to provide the closure force to the inner tube, and wherein the proximal spring is configured to limit the closure force the distal spring can provide to the inner tube. 
     
     
         20 . The ultrasonic surgical instrument of  claim 18 , wherein the distal spring is preloaded at less than 10 pounds. 
     
     
         21 . The ultrasonic surgical instrument of  claim 20 , wherein the proximal spring is preloaded at about 12.5 pounds. 
     
     
         22 . An ultrasonic surgical system, comprising:
 an ultrasonic transducer; and   a surgical instrument, comprising:
 an end effector, comprising:
 an ultrasonic blade; and 
 a clamp arm movable relative to the ultrasonic blade between an open position and a closed position; 
 
 a shaft assembly extending proximally from the end effector, wherein the shaft assembly comprises:
 an outer tube; and 
 an inner tube movable relative to the outer tube, wherein the inner tube is operably coupled to the clamp arm, wherein the clamp arm is configured to move between the open position and the closed position based on movement of the inner tube, and wherein the inner tube is configured to apply a closure force to the clamp arm; 
 
 an ultrasonic waveguide extending proximally from the ultrasonic blade through the shaft assembly, wherein the ultrasonic waveguide operably coupled to the ultrasonic transducer; 
 a housing extending proximally from the shaft assembly, wherein the housing comprises an actuator, wherein the actuator is movable between an unactuated position and an actuated position, and wherein inner tube is configured to apply the closure force to the clamp arm based on movement of the actuator; and 
 a force limiting system operably coupled to the actuator and the inner tube, wherein the force limiting system is configured to limit the closure force the inner tube can provide to the clamp arm based on movement of the actuator between the unactuated position and the actuated position. 
   
     
     
         23 . The ultrasonic surgical system of  claim 22 , wherein proximal movement of the inner tube moves the clamp arm towards the closed position. 
     
     
         24 . The ultrasonic surgical system of  claim 22 , wherein distal movement of the inner tube moves the clamp arm towards the open position. 
     
     
         25 . The ultrasonic surgical system of  claim 22 , wherein the actuator is moveable relative to the housing between the unactuated position, the actuated position, and an intermediate position between the unactuated position and the actuated position, and wherein the force limiting system is configured to exclusively limit the closure force the inner tube can apply to the clamp arm based on movement of the actuator between the intermediate position to the actuated position. 
     
     
         26 . The ultrasonic surgical system of  claim 22 , wherein the force limiting system comprises a proximal spring and a distal spring. 
     
     
         27 . The ultrasonic surgical system of  claim 26 , wherein the distal spring is operably coupled to the inner tube, wherein the inner tube is configured to provide the closure force to the inner tube, and wherein the proximal spring is configured to limit the closure force the distal spring can provide to the inner tube. 
     
     
         28 . The ultrasonic surgical system of  claim 26 , wherein the distal spring is preloaded at less than 10 pounds. 
     
     
         29 . The ultrasonic surgical system of  claim 26 , wherein the proximal spring is preloaded at about 12.5 pounds. 
     
     
         30 . A surgical instrument, comprising:
 an end effector comprising
 an ultrasonic blade; and 
 a clamp arm pivotable relative to the ultrasonic blade between an open position and a closed position; 
   an actuation member operably coupled to the clamp arm, wherein the clamp arm is moveable between the open position and the closed position based on axial movement of the actuation member, and wherein the actuation member is configured to apply a closure force to the clamp arm; and   a force control system comprising a distal spring and a proximal spring, wherein the distal spring is configured to provide the closure force to the actuation member, and wherein the proximal spring is configured to limit the closure force the distal spring can provide to the actuation member.   
     
     
         31 . The surgical instrument of  claim 30 , further comprising an actuator operably coupled to the force control system, wherein the actuator is movable between an unactuated position, an intermediate position, and an actuated position, and wherein the proximal spring is configured to exclusively limit the closure force the distal spring can provide to the actuation member based on movement of the actuator between the intermediate position and the actuated position. 
     
     
         32 . The surgical instrument of  claim 30 , wherein the distal spring is preloaded at less than 10 pounds. 
     
     
         33 . The surgical instrument of  claim 30 , wherein the proximal spring is preloaded at about 12.5 pounds.