Gear shaft for accommodating thermal expansion and transmission system incorporating the same
AssigneeTextron Innovations Inc.
InventorRyan Thomas Ehinger
Life of this patent
Estimating the term…
Abstract
A gear shaft allows a ceramic bearing to be used in environments where gear steel is desirable for driving a gear. The gear shaft includes a gear region and a bearing region. A bearing can be disposed about the bearing region of the gear shaft. A gear can be disposed about the gear region of the gear shaft. The bearing includes a ceramic material. The gear region of the gear shaft includes gear steel, whereas the bearing region of the gear shaft includes a bearing-region material that has a coefficient of thermal expansion (CTE) that is close to the CTE of the ceramic material.
Claims18
A gear assembly comprising:
- a gear shaft having a gear region and a bearing region;
- a first bearing disposed about the bearing region of the gear shaft;
- and
- a gear disposed about the gear region of the gear shaft,
- wherein the first bearing includes a ceramic material,
- wherein the bearing region of the gear shaft includes a bearing-region material other than the ceramic material that has a coefficient of thermal expansion (CTE) that is within 3.5×10−6 K−1 of the CTE of the ceramic material;
- and
- wherein the first bearing assembly includes an inner race formed of the ceramic material, the inner race extending about the gear shaft, an outer race extending about the inner race, and a plurality of rollers disposed between the first race and the second race.
A gear shaft for rotatably driving a gear while being rotatably supported by a bearing formed of a ceramic material, the gear shaft comprising:
- a gear region for supporting the gear;
- and
- a bearing region for supporting the bearing, the bearing region being fixed to the gear region;
- wherein the bearing region includes a bearing-region material other than the ceramic material that has a coefficient of thermal expansion (CTE) that is within 3.5×10−6K−1 of the CTE of the ceramic material;
- and
- wherein the gear shaft defines a first cylindrical internal chamber and a second cylindrical internal chamber interposed by an internal support structure.
An aircraft comprising:
- a rotor assembly comprising a rotor shaft;
- and
- a transmission for driving the rotor shaft, the transmission comprising a gear assembly, the gear assembly comprising:
- a gear shaft having a gear region and a bearing region;
- a first bearing disposed about the bearing region of the gear shaft;
- and
- a gear disposed about the gear region of the gear shaft,
- wherein the first bearing includes a ceramic material, and
- wherein the bearing region of the gear shaft includes a bearing-region material that has a coefficient of thermal expansion (CTE) that is within 3.5×10−6 K−1 of the CTE of the ceramic material.
Dependencies are inferred from the claim text.