Motorized surgical cutting and fastening instrument having a magnetic drive train torque limiting device

1. A surgical cutting and fastening instrument comprising:

an end effector comprising:

a cutting instrument for cutting tissue clamped in the end effector; and

fastening means for fastening the tissue cut by the cutting instrument;

a shaft connected to the end effector, the shaft comprising a drive train for powering the end effector;

an electric, DC motor connected to the drive train for powering the drive train; and

a torque-limiting device connected between to an output pole of the motor and an input pole of the drive train.

2. The surgical cutting and fastening instrument of claim 1 further comprising a handle connected to the shaft, wherein the motor is located in the handle.

3. The surgical cutting and fastening instrument of claim 1 , wherein the torque-limiting device comprises a clutch.

4. The surgical cutting and fastening instrument of claim 3 , wherein the clutch comprises an electromagnetic clutch.

5. The surgical cutting and fastening instrument of claim 4 , wherein the electromagnetic clutch comprises:

a horseshoe-shaped stator having a first magnetic disk at a first end of the stator and a second magnetic disk at a second end of the stator, wherein the first magnetic disk is connected to the output pole of the motor and the second magnetic disk is connected to the input pole of the drive train; and

a coil, such that when the coil conducts a current, the electromagnetic flux from the coil actuates the clutch.

6. The surgical cutting and fastening instrument of claim 5 , wherein:

when the coil conducts the current, the two magnetic disks are attracted to each other so that they come in contact; and

when the coil is not conducting the current, the two magnetic disks are not in contact.

7. The surgical cutting and fastening instrument 6 , wherein the coil is wrapped around the stator.

8. The surgical cutting and fastening instrument of claim 3 , wherein the clutch comprises a permanent magnet.

9. The surgical cutting and fastening instrument of claim 8 , wherein the clutch comprises a horseshoe-shaped stator having a first disk at a first end of the stator and a second disk at a second end of the stator, wherein the first disk is connected to the output pole of the motor and the second disk is connected to the input pole of the drive train, and wherein the permanent magnet is connected to the output pole of the motor and attracts the input pole of the drive train such that the magnetic disks are in contact.

10. The surgical cutting and fastening instrument of claim 1 , wherein the end effector comprises:

upper and lower opposing jaws for clamping the tissue in the end effector; and

wherein the cutting instrument comprises a knife that transverses for transversing a longitudinal channel of the lower jaw.

11. The surgical cutting and fastening instrument of claim 10 , wherein the fastening means comprises at least one RF electrode.

12. The surgical cutting and fastening instrument of claim 1 , wherein the torque-limiting device comprises a permanent magnet, horseshoe-shaped stator having a first disk at a first end of the stator and a second disk at a second end of the stator, wherein the first disk is connected to the output pole of the motor and the second disk is connected to the input pole of the drive train.

13. The surgical cutting and fastening instrument of claim 1 , wherein the instrument is a linear endocutter.

14. The surgical cutting and fastening instrument of claim 1 , wherein the instrument is a circular cutting and stapling device.

15. The surgical cutting and fastening instrument of claim 1 , wherein the fastening means comprises a staple cartridge.