Patent ID: 8336752

Claim:
A surgical instrument for driving an end effector comprising: a handle having an elongate tubular member extending from the distal end of the handle; a driver movable within the elongate tubular member and operable on the end effector; an energy storage mechanism comprising a spring having an energized position and a cylinder having an interior space, the spring being at least partially positioned within the handle and operable on the driver to advance the driver within the elongate tubular member to drive the end effector; a piston connected to the spring and dividing the interior space of the cylinder into a first side and a second side, an incompressible hydraulic fluid being disposed in the first side of the cylinder and arranged in relation to the piston and spring so that the spring biases the piston against the hydraulic fluid when the spring is in the energized position; and an actuation mechanism comprising a valve, the valve for opening and closing a passage communicating the first side of the cylinder with the second side of the cylinder to control movement of the driver.