US 11,987,378 B2
Auxiliary power unit adaptive cooldown cycle system and method
Robert Mallette, Phoenix, AZ (US); and Bradley Volkmann, Phoenix, AZ (US)
Assigned to HONEYWELL INTERNATIONAL INC., Charlotte, NC (US)
Filed by HONEYWELL INTERNATIONAL INC., Charlotte, NC (US)
Filed on Jan. 17, 2023, as Appl. No. 18/155,090.
Application 18/155,090 is a division of application No. 17/658,767, filed on Apr. 11, 2022, granted, now 11,572,192.
Application 17/658,767 is a division of application No. 16/244,336, filed on Jan. 10, 2019, granted, now 11,305,885, issued on Apr. 19, 2022.
Prior Publication US 2023/0211891 A1, Jul. 6, 2023
Int. Cl. F02C 7/14 (2006.01); B64D 33/02 (2006.01); B64D 33/08 (2006.01); B64D 41/00 (2006.01); F02C 9/28 (2006.01)
CPC B64D 41/00 (2013.01) [B64D 33/02 (2013.01); B64D 33/08 (2013.01); F02C 7/14 (2013.01); F02C 9/28 (2013.01); B64D 2033/0213 (2013.01); F05D 2220/50 (2013.01); F05D 2260/20 (2013.01); F05D 2270/303 (2013.01); F05D 2270/3032 (2013.01); F05D 2270/304 (2013.01)] 8 Claims
OG exemplary drawing
 
8. An auxiliary power unit (APU) system, comprising:
an APU configured to rotate at a rotational speed;
one or more sensors disposed within the APU, each of the one or more sensors configured to sense an operational parameter of the APU and supply a sensor signal representative of the operational parameter; and
an APU control unit in operable communication with the APU and coupled to receive the sensor signals from the one or more sensors, the APU control unit further coupled to receive a shutdown signal and operable, in response to the shutdown signal, to:
reduce the rotational speed of the APU to a predetermined cooldown speed magnitude that ensures combustor inlet temperature has reached a predetermined temperature value;
determine, based on one or more of the operational parameters of the APU, when a lean blowout of the APU is imminent; and
when a lean blowout is imminent, increase fuel flow to prevent the lean blowout.