Surgical instrument with variable clamping force

An ultrasonic surgical instrument, comprising:

• (a) a shaft assembly including an acoustic waveguide;
• (b) an end effector distally extending from the shaft assembly, including:
• (i) an ultrasonic blade in acoustic communication with the acoustic waveguide, and
• (ii) a clamp arm movably secured relative to the ultrasonic blade and configured to move from an open position toward a closed position, wherein the clamp arm is further configured to compress tissue against the ultrasonic blade with a clamp force while moving the clamp arm toward the closed position;
• (c) a drive member operatively connected to the clamp arm and configured to selectively actuate from a first position toward a second position to thereby respectively direct the clamp arm from the open position toward the closed position;
• and
• (d) a force limiter operatively connected between the drive member and the clamp arm, wherein the force limiter is configured to transfer movement from the drive member toward the clamp arm and limit force transferred therethrough to a first adjusted clamp force or a second adjusted clamp force for restricting the clamp force at the clamp arm respectively according to the first or second adjusted clamp force, wherein the force limiter is configured to be selectable between the first adjusted clamp force and the second adjusted clamp force by an operator.

An ultrasonic surgical instrument, comprising:

• (a) a body;
• (b) a shaft assembly distally extending from the body and including an acoustic waveguide;
• (c) an end effector distally extending from the shaft assembly, including:
• (i) an ultrasonic blade in acoustic communication with the acoustic waveguide, and
• (ii) a clamp arm movably secured relative to the ultrasonic blade and configured to move from an open position toward a closed position, wherein the clamp arm is further configured to compress tissue against the ultrasonic blade with a clamp force while moving the clamp arm toward the closed position;
• (d) a trigger operatively connected to the clamp arm and configured to selectively actuate to thereby respectively direct the clamp arm from the open position toward the closed position;
• and
• (e) a spring stack operatively connected between the trigger and the clamp arm, wherein the spring stack is configured to transfer movement from the trigger toward the clamp arm and limit force transferred therethrough for restricting the clamp force at the clamp arm.

A method of limiting a clamp force of an ultrasonic surgical instrument, the ultrasonic surgical instrument including (a) a shaft assembly including an acoustic waveguide;

• (b) an end effector distally extending from the shaft assembly, including:
• (i) an ultrasonic blade in acoustic communication with the acoustic waveguide, and (ii) a clamp arm movably secured relative to the ultrasonic blade and configured to move from an open position toward a closed position, wherein the clamp arm is further configured to compress tissue against the ultrasonic blade with the clamp force while moving the clamp arm toward the closed position;
• (c) a drive member operatively connected to the clamp arm and configured to selectively actuate from a first position toward a second position to thereby respectively direct the clamp arm from the open position toward the closed position;
• and (d) a force limiter operatively connected between the drive member and the clamp arm, wherein the force limiter is configured to transfer movement from the drive member toward the clamp arm and limit force transferred therethrough to a first adjusted clamp force or a second adjusted clamp force for restricting the clamp force at the clamp arm respectively according to the first or second adjusted clamp force, wherein the force limiter is configured to be selectable between the first adjusted clamp force and the second adjusted clamp force by an operator, the method comprising:
• (a) selectively moving at least a portion of the force limiter to thereby adjust the clamp force from the first adjusted clamp force to the second adjusted clamp force and limit the clamp force applied via the clamp arm to the second adjusted clamp force.