Rotational energy storage device and tools incorporating same

A rotational energy storage device comprising

• a shaft;
• a ring rotatably disposed about said shaft;
• at least one rolling element compressed between said shaft and said ring to form contact zones with each;
• a back-up ring disposed concentrically about said ring;
• and
• a cam geometry disposed on at least one member selected from the group consisting of said ring, said shaft, said at least one rolling element, said back-up ring, and combinations thereof;
• said cam geometry comprised of a home position located between a high stiffness camming region and a low stiffness camming region, said high stiffness camming region being configured to provide a higher restoring torque on said at least one rolling element toward said home position than said low stiffness camming region and said home position being configured to provide position of minimum interference along said cam geometry between said ring, said at least one rolling element, and said shaft;
• such that upon applying a torque to said ring and thereby inducing rotation between said ring and said shaft in a first direction, said at least one rolling compression between said ring and said shaft in said low stiffness camming region to elastically deform said ring, said shaft, and said at least one rolling element and store potential energy therein,
• and upon applying a torque in an opposite direction and thereby inducing rotation of an equal magnitude to said rotation in said first direction between said ring and said shaft in a second direction, said at least one rolling element rolls between said ring and said shaft into said high stiffness camming region to elastically deform said ring and said shaft and said at least one rolling element and store potential energy therein in an amount greater than when said at least one rolling element rolls between said ring and said shaft into said low stiffness camming region.

A rotational energy storage device comprising:

• a shaft;
• a ring rotatably disposed about said shaft;
• and
• a plurality of rolling elements compressed between said shaft and said ring to form contact zones with each;
• a cam geometry disposed on at least one member selected from the group consisting of said ring, said shaft, and said plurality of rolling elements;
• said cam geometry comprised of a home position located between a high stiffness camming region an a low stiffness camming region, said high stiffness camming region being configured to provide a higher restoring torque on said plurality of rolling elements toward said home position than said low stiffness camming region and said home position being configured to provide a position of minimum interference along said cam geometry between said ring, said plurality of rolling elements, and said shaft;
• such that upon applying a torque to said ring and thereby inducing rotation between said ring and said shaft in a first direction, said plurality of rolling elements roll from the home position into a state of greater compression between said ring and said shaft in said low stiffness camming region to elastically deform said ring, said shaft, and said plurality of rolling elements and store potential energy therein;
• and upon applying a torque in an opposite direction and thereby inducing rotation of an equal magnitude to said rotation in said first direction between said ring and said shaft in a second direction, plurality of rolling elements roll between said ring and said shaft into said high stiffness camming region to elastically deform said ring and said shaft and said plurality of rolling elements and store potential energy therein in an amount greater than when said at least one rolling element rolls between said ring and said shaft into said low stiffness camming region.