Tool holding mechanism for a motor driven surgical instrument

An apparatus for attaching a tool bit to a surgical instrument having a housing which contains a motor that drives a spindle, said apparatus comprising:

• a body having a first end portion for attaching to the spindle, a central portion with a cavity therein, and a second end portion having an aperture therethrough in communication with the cavity wherein the aperture is adapted to receive a shaft of the tool bit that extends into the cavity;
• a first lock pawl movably mounted in the cavity and having a first tab for entering a slot in the shaft when said first lock pawl is in a first position and retracted from the slot when said first lock pawl is in a second position;
• and
• an actuator which engages said first lock pawl to produce movement between the first and second positions further comprising a body rotational restrainer adapted to be fixedly connected to the housing;
• and
• wherein said first lock pawl has a second tab for engaging said restrainer when said first lock pawl is in the second position to prevent rotation of said body, and disengaging said restrainer when said first lock pawl is in the first position.

An apparatus for attaching a tool bit to a surgical instrument having a housing which contains a motor that drives a spindle, said apparatus comprising:

• a body having a first end portion for attaching to the spindle, a central portion with a cavity therein, and a second end portion having an aperture therethrough in communication with the cavity wherein the aperture is adapted to receive a shaft of the tool bit that extends into the cavity;
• a first lock pawl movably mounted in the cavity and having a first tab having a flat surface for entering a slot in the shaft when said first lock pawl is in a first position and retracted from the slot when said first lock pawl is in a second position;
• and
• an actuator which engages said first lock pawl to produce movement between the first and second positions further comprising a second lock pawl movably mounted in the cavity having a first tab for entering a slot in the shaft when said second lock pawl is in a first position and retracted from the slot when said second lock pawl is in a second position further comprising a restrainer connected to the housing;
• and wherein said first and second lock pawls have a second tab that engages said restrainer when said first and second lock pawls are in the second position to prevent rotation of said body, and disengage said restrainer in the first position of said first and second lock pawls.

An apparatus for attaching a tool bit to a surgical instrument having a housing which contains a motor that drives a spindle, said apparatus comprising:

• a body having a first end portion for attaching to the spindle, a central portion with a cavity therein, and a second end portion having an aperture therethrough in communication with the cavity wherein the aperture is adapted to receive a shaft of the tool bit that extends into the cavity;
• a first lock pawl movably mounted in the cavity and having a first tab having a flat surface for entering a slot in the shaft when said first lock pawl is in a first position and retracted from the slot when said first lock pawl is in a second position;
• and
• an actuator which engages said first lock pawl to produce movement between the first and second positions wherein said actuator comprises:
• a ring extending around said body and engaging said first lock pawl to produce movement between the first and second positions upon said ring being moved along said body;
• and
• a manually operable driver coupled to said housing for engaging said ring to move said ring along said body wherein said first lock pawl has a notch;
• and further comprising a ball located within the notch of said first pawl, wherein said ball when acted upon by centrifugal force due to rotation of said body urges said ring into a given position along said body.

An apparatus for attaching a tool bit to a surgical instrument having a housing which contains a motor that drives a spindle, said apparatus comprising:

• a body having a first end portion for attaching to the spindle, a central portion with a cavity therein, and a second end portion having an aperture therethrough in communication with the cavity wherein the aperture is adapted to receive a shaft of the tool bit that extends into the cavity;
• a first lock pawl movably mounted in the cavity and having a first tab having a flat surface for entering a slot in the shaft when said first lock pawl is in a first position and retracted from the slot when said first lock pawl is in a second position;
• and
• an actuator which engages said first lock pawl to produce movement between the first and second positions wherein said actuator comprises:
• a ring extending around said body and engaging said first lock pawl to produce movement between the first and second positions upon said ring being moved along said body;
• and
• a manually operable driver coupled to said housing for engaging said ring to move said ring along said body wherein said manually operable driver comprises a fork with two tines engaging said ring, and a handle attached to the fork.

A surgical instrument comprising:

• a housing;
• a motor within said housing;
• a restrainer fixedly connected to said housing;
• a body within said housing and having a first end portion connected to said motor for rotation about an axis, a central portion with a cavity therein, and a second end portion having a first aperture therethrough in communication with the cavity;
• a first lock pawl and a second lock pawl pivotally mounted in the cavity, and each respective lock pawl having a first tab projecting toward the axis of rotation and having a second tab projecting away from the axis of rotation, the second tab engaging the restrainer when the respective lock pawl is in a first position to prevent rotation of said body and disengaging said restrainer when the respective lock pawl is in a second position;
• a ring extending around said body and producing pivotal movement of said first and second lock pawls when said ring is moved along said body;
• a manually operable shift lever pivotally coupled to said housing and engaging said ring to produce movement of said ring along said body thereby pivoting said first and second lock pawls;
• and
• a tool bit with a shaft extending through the first aperture in the second end portion of said body and into the cavity, and the shaft having an axial stop;
• wherein the first tab of at least one of said first and second lock pawls engages the axial stop on the shaft of the tool bit when said first and second lock pawls are in the second position, and disengages the axial stop when said first and second lock pawls are in the first position.