Torque-based transition between operating gears
A surgical tool configured to receive rotary inputs from a robotic surgical system. The surgical tool comprises a distal end effector comprising jaws for clamping tissue therebetween, an intermediate shaft portion coupled to the distal end effector, and a proximal housing coupled to the intermediate shaft portion. The proximal housing comprises an arrangement of rotary drives comprising a first rotary drive. The first rotary drive comprises an input shaft configured to receive a rotary input from the robotic surgical system, a transition nut slidably positioned on the input shaft, and an output gear. The first rotary drive further comprises a high-speed gear configured to selectively drive the output gear, a high-torque gear configured to selectively drive the output gear, and a spring arrangement configured to bias the transition nut along the input shaft from a high-speed operating state to a high-torque operating state upon obtaining a threshold torque.
1. A surgical tool configured to receive rotary inputs from a robotic surgical system, the surgical tool comprising:
a distal end effector comprising jaws for clamping tissue therebetween;
an intermediate shaft portion coupled to the distal end effector; and
a proximal housing coupled to the intermediate shaft portion, the proximal housing comprising an arrangement of rotary drives comprising a first rotary drive, the first rotary drive comprising:
an input shaft configured to receive a rotary input from the robotic surgical system to effect rotation of the input shaft about a rotation axis;
a transition nut rotatably driven by the input shaft about the rotation axis, wherein the transition nut is slidably positioned on the input shaft;
an output gear;
a high-speed gear configured to selectively drive the output gear;
a high-torque gear configured to selectively drive the output gear; and
a spring configured to apply a spring force to bias the transition nut along the input shaft toward a high-speed operating state, in which the transition nut is in driving engagement with the high-speed gear, wherein the application of a threshold torque to the transition nut is configured to overcome the spring force to move the transition nut toward a high-torque operating state, in which the transition nut is in driving engagement with the high-torque gear.
2. The surgical tool of claim 1 , wherein the transition nut comprises:
a perimeter;
a first end; and
an array of sloping teeth around the perimeter extending to the first end.
3. The surgical tool of claim 2 , wherein the high-torque gear comprises an array of complementary sloping receptacles configured to receive the array of sloping teeth when the transition nut is in the high-torque operating state.
4. The surgical tool of claim 3 , wherein the transition nut further comprises:
a second end; and
a first array of teeth around the perimeter extending to the second end.
5. The surgical tool of claim 4 , further comprising a grasping gear drivingly engaged with the high-speed gear, wherein the grasping gear comprises a second array of teeth configured to receive the first array of teeth when the transition nut is in the high-speed operating state.
6. The surgical tool of claim 5 , wherein the spring is configured to bias the first array of teeth toward the second array of teeth.
7. The surgical tool of claim 6 , further comprising a second spring configured to bias the first end of the transition nut away from the second end of the transition nut.
8. The surgical tool of claim 1 , further comprising an output shaft drivingly coupled to the output gear, wherein the output shaft is configured to drive a rotary drive screw to effect a closure of the jaws.
9. The surgical tool of claim 1 , wherein the first rotary drive further comprises a gear train comprising the high-speed gear, and wherein the gear train comprises a speed ratio greater than one.
10. A surgical tool for a robotic surgical system, the surgical tool comprising:
a distal end effector comprising jaws for clamping tissue therebetween;
an intermediate shaft portion coupled to the distal end effector; and
a proximal housing coupled to the intermediate shaft portion, the proximal housing comprising:
an input shaft configured to receive a rotary input from the robotic surgical system to effect rotation of the input shaft about a rotation axis;
a transition nut slidably positioned on the input shaft along an axis;
an output gear;
a first rotary drive configured to selectively drive the output gear;
a second rotary drive configured to selectively drive the output gear; and
a spring axially aligned with the rotation axis and configured to bias the transition nut along the input shaft to couple the input shaft with either the first rotary drive or the second rotary drive based on a threshold torque applied to the transition nut.
11. The surgical tool of claim 10 , wherein the transition nut rotates with the input shaft.
12. The surgical tool of claim 11 , wherein the spring is configured to apply a spring force to bias the transition nut toward the second rotary drive, wherein the application of the threshold torque to the transition nut is configured to overcome the spring force to move the transition nut out of engagement with the second rotary drive.
13. The surgical tool of claim 12 , wherein the transition nut comprises:
a perimeter;
a first end;
an array of sloping teeth around the perimeter extending to the first end;
a second end;
a first array of teeth around the perimeter extending to the second end; and
a second spring configured to bias the first end away from the second end.
14. The surgical tool of claim 13 , wherein the first rotary drive comprises a high-torque gear comprising complementary sloping receptacles configured to receive the array of sloping teeth when the input shaft is engaged with the first rotary drive, and wherein the surgical tool is in a high-torque operating state when the first rotary drive is engaged with the input shaft.
15. The surgical tool of claim 13 , wherein the second rotary drive comprises a high-speed gear and a grasping gear drivingly engaged with the high-speed gear, wherein the grasping gear comprises a second array of teeth configured to receive the first array of teeth when the input shaft is engaged with the second rotary drive, and wherein the surgical tool is in a high-speed operating state when the second rotary drive is engaged with the input shaft.
16. The surgical tool of claim 15 , wherein the second rotary drive further comprises a gear train comprising the high-speed gear, and wherein the gear train comprises a speed ratio greater than one.
17. The surgical tool of claim 10 , further comprising an output shaft drivingly coupled to the output gear, wherein the output shaft is configured to drive a rotary drive screw to effect a closure of the jaws.
18. A rotary drive system for rotating a drive screw in a robotic surgical tool, the rotary drive system comprising:
an input shaft configured to receive a rotary input from a robotic surgical system to effect rotation of the input shaft about a rotation axis;
a transition nut slidably positioned on the input shaft;
an output gear drivingly coupled to an output shaft;
a first rotary drive configured to selectively drive the output gear in a first operating state;
a second rotary drive configured to selectively drive the output gear in a second operating state; and
a spring configured to apply a spring force along the rotation axis to bias the transition nut along the input shaft into engagement with the first rotary drive, wherein the application of a threshold torque to the transition nut is configured to overcome the spring force to move the transition nut into engagement with the second rotary drive.
19. The rotary drive system of claim 18 , wherein the first rotary drive comprises a high-torque gear that comprises complementary sloping receptacles configured to receive an array of sloping teeth on the transition nut when the input shaft is engaged with the first rotary drive.
20. The rotary drive system of claim 19 , wherein the second rotary drive comprises a high-speed gear and a grasping gear drivingly engaged with the high-speed gear, wherein the grasping gear comprises an array of teeth configured to engage the transition nut when the input shaft is engaged with the second rotary drive.