Transmission, a ring gear thereof, and a method of operating the same

A method of operating a transmission defining a sun gear that is coupled coaxially, via at least one planetary gear supported by a carrier, to a ring gear for rotation around an axis, the transmission configured to receive an input to supply an output in response to arresting of rotation of the ring gear around the axis, the method comprising:

• engaging a pawl with a plurality of tooth surfaces of the ring gear distributed around the axis to not obstruct, by the pawl, ratcheting of the pawl on the ring gear in a first angular direction and to prevent rotation of the ring gear in a second angular direction by the pawl, the first and second angular directions being opposite to each other and lateral to the axis;
• engaging an opposing pawl with a plurality of opposing tooth surfaces of the ring gear distributed around the axis to not obstruct, by the opposing pawl, ratcheting of the opposing pawl on the ring gear in the second angular direction and to prevent rotation of the ring gear in the first angular direction by the opposing pawl;
• and
• while the pawl is ratcheting on the ring gear, supporting the pawl using a plurality of protrusions axially co-located with the plurality of tooth surfaces, each protrusion of the plurality of protrusions extending radially in-between a corresponding tooth surface of the plurality of tooth surfaces and a corresponding opposing tooth surface of the plurality of opposing tooth surfaces.

A transmission configured to receive an input so as to supply an output via an input-output path, comprising:

• a sun shaft defining a plurality of sun gears integrally coupled to each other for common rotation around an axis;
• a plurality of planetary gears engaged with the plurality of sun gears;
• a carrier supporting the plurality of planetary gears so as to rotate around the axis in common with the plurality of planetary gears;
• a plurality of bi-directional ratchets defining a plurality of ring gears, each of the plurality of bi-directional ratchets including
• a corresponding ring gear of the plurality of ring gears coupled to a corresponding sun gear of the plurality of sun gears via a corresponding planetary gear of the plurality of planetary gears for rotation around the axis, the corresponding ring gear defining
• a corresponding plurality of tooth surfaces distributed around the axis for ratcheting, and
• a corresponding plurality of opposing tooth surfaces distributed around the axis for ratcheting,
• a corresponding pawl configured to be actuatable to engage with the corresponding plurality of tooth surfaces to allow ratcheting rotation of the corresponding ring gear in a first angular direction while preventing rotation of the corresponding ring gear in a second angular direction opposite to the first angular direction, and
• a corresponding opposing pawl configured to be actuatable to engage with the corresponding plurality of opposing tooth surfaces to allow ratcheting rotation of the corresponding ring gear in the second angular direction while preventing rotation of the corresponding ring gear in the first angular direction;
• and
• an actuator coupled to the plurality of bi-directional ratchets to actuate the plurality of bi-directional ratchets to change a gear ratio between the input and the output by causing a pawl of the plurality of bi-directional ratchets and an opposing pawl of the plurality of bi-directional ratchets to hold stationary a ring gear of the bi-directional ratchets while allowing ring gears of the bi-directional ratchets other than the ring gear to rotate without ratcheting so as to establish the input-output path between the carrier and a sun gear of the sun shaft coupled to the ring gear, wherein:
• the ring gear defines a tooth surface and an opposing tooth surface spaced apart from, axially co-located with, and facing the tooth surface;
• and
• the ring gear further comprises a protrusion extending radially in-between the tooth surface and the opposing tooth surface to support the pawl and the opposing pawl, the protrusion tapering from a radially-inner end adjacent to the tooth surface and an opposing radially-inner end adjacent to the opposing tooth surface.