Patent ID: 7251942

Claim:
An auxiliary power unit, comprising: a combustor; a turbine having an output shaft, the turbine in fluid communication with at least a portion of the combustor; a compressor coupled to the turbine output shaft; a starter-generator unit having at least a rotor mounted on a rotor shaft; and a quill shaft assembly directly coupled between the turbine output shaft and the starter-generator unit rotor shaft, the quill shaft assembly comprising: a hollow quill shaft having at least a first end, a second end, an inner surface, and an outer surface, the hollow quill shaft surrounding at least portions of the turbine output shaft and the starter-generator unit rotor shaft, a first set of splines formed on the quill shaft outer surface at least proximate the quill shaft first end, a second set of splines formed on the quill shaft outer surface at least proximate the quill shaft second end, a turbine shaft coupling coupled to, and surrounding a portion of, the turbine output shaft, the turbine shaft coupling including at least a first end, a second end, and an inner surface, a third set of splines formed on the turbine shaft coupling inner surface and engaging the first set of splines, a rotor shaft coupling coupled to, and surrounding at least a portion of, the starter-generator unit rotor shaft, the rotor shaft coupling including at least a first end, a second end, and an inner surface, and a fourth set of splines formed on the rotor shaft coupling inner surface and engaging the second set of splines.