US 11,808,211 B2
Multi-speed transmission to control variable APU speed and constant generator output frequency
Jonathan C. Dell, Elgin, IL (US); David S. Behling, Belvidere, IL (US); and Glenn C. Lemmers, Jr., Loves Park, IL (US)
Assigned to HAMILTON SUNDSTRAND CORPORATION, Charlotte, NC (US)
Filed by Hamilton Sundstrand Corporation, Charlotte, NC (US)
Filed on Apr. 8, 2022, as Appl. No. 17/716,106.
Prior Publication US 2023/0323817 A1, Oct. 12, 2023
Int. Cl. F02C 7/32 (2006.01); F01D 15/10 (2006.01)
CPC F02C 7/32 (2013.01) [F01D 15/10 (2013.01); F05D 2220/50 (2013.01); F05D 2220/7642 (2013.01); F05D 2260/4023 (2013.01); F05D 2260/4031 (2013.01); F05D 2270/02 (2013.01)] 15 Claims
OG exemplary drawing
 
1. An aircraft power system comprising:
an auxiliary power unit (APU) configured to output a first APU rotational power during a first condition and a second APU rotational power during a second condition different from the first condition;
a transmission unit configured to receive the first APU rotational output power from the APU, the transmission unit configured to output a transmission rotational power based on the first APU rotational output power and to output the transmission rotational power based on the second APU rotational output power;
a drive shaft rotatably coupled between the APU and the transmission unit, wherein the APU drives the drive shaft to rotate at a first rotational speed so as to deliver the first APU rotational output power and to rotate at a second rotational speed so as to deliver the second APU rotational output power; and
a generator configured to receive the transmission rotational power and to produce an alternating current (AC) voltage having a target frequency based on the transmission rotational power, wherein the first condition is a first altitude range at which the APU drives the drive shaft at a first speed of about 21,630 rotations per minute (RPM) and the second condition is a second altitude range at which the APU drives the APU drive shaft at a second speed falling within a second speed range which ranges from about 24,030 RPM.