(19) TZZ ¥_T

(11) EP 2 772 438 B1

(12) EUROPEAN PATENT SPECIFICATION

(45) Date of publication and mention (51) Int Cl.: of the grant of the patent: B64D 41/00 (2006.01) 20.01.2016 Bulletin 2016/03

(21) Application number: 14154763.8

(22) Date of filing: 11.02.2014

(54) Auxiliary power units (APUs) and methods and sy stems for activation and deactivation of a load compressor therein Hilfskraftquellen (APUs) und Verfahren und Systeme zur Aktivierung und Deaktivierung eines Lastverdichters darin Unités de puissance auxiliaire (APU) et procédés et systèmes pour l’activation et la désactivation d’un compresseur de charge dans celles-ci

(84) Designated Contracting States: (72) Inventors: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB • Jan, David K. GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO Morristown, NJ New Jersey 07962-2245 (US) PL PT RO RS SE SI SK SM TR • Zollars, Christopher Morristown, NJ New Jersey 07962-2245 (US) (30) Priority: 28.02.2013 US 201313781239 (74) Representative: Houghton, Mark Phillip (43) Date of publication of application: Patent Outsourcing Limited 03.09.2014 Bulletin 2014/36 1 King Street Bakewell, Derbyshire DE45 1DZ (GB) (73) Proprietor: Honeywell International Inc. Morris Plains, NJ 07950 (US) (56) References cited: EP-A2- 2 347 956 GB-A- 2 076 897 US-A- 4 091 613

Note: Within nine months of the publication of the mention of the grant of the European patent in the European Patent Bulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with the Implementing Regulations. Notice of opposition shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). EP 2 772 438 B1

Printed by Jouve, 75001 PARIS (FR) 1 EP 2 772 438 B1 2

Description position. [0004] In a conventional operating APU, the activated TECHNICAL FIELD load compressor is engaged with the operating APU en- gine and the deactivated load compressor is disengaged [0001] The present invention generally relates to aux- 5 from the operating APU engine. The load compressor iliary power units ("APU"s), and more particularly relates may be engaged with and disengaged from the operating to methods and systems for activation and deactivation APU engine via one or more friction clutches. Unfortu- of a load compressor therein. nately, friction clutches that have been used to engage the load compressor with the operating APU engine and BACKGROUND 10 disengage the load compressor therefrom tend to be heavy and have less than ideal reliability in APUs due to [0002] An operating aircraft auxiliary power unit (APU) high rotational speeds. High rotational speeds impose provides energy for functions other than propulsion. An high inertial loading, leading to excessive temperatures APU generally consists of a gas turbine engine (herein- and accelerated wear and failure of the friction clutch after referred to as an "APU engine), a generator, and a 15 components, leading to clutch failures. In addition, oil- load compressor (LC). Before the main propulsion en- cooled friction clutches impose oil cooling system pen- gines are started, the APU engine is started, generally alties. Dynamic disconnect clutches can also be used for by a battery or hydraulic accumulator and fuel. The op- disengaging the load compressor in the operating APU, eratingAPU provides auxiliary electrical powerand pneu- but can only disengage at speed and cannot re-engage matic power to the aircraft while the main propulsion en- 20 until the APU is shut down, thereby limiting operational gines are shut down, such as during aircraft ground op- flexibility. A relevant disclosure of an APU can be found erations and provides backup electrical and pneumatic in EP 2 347 956. power for in-flight operations. The operating APU sup- [0005] Accordingly, it is desirable to provide auxiliary plies the electrical power via the generator which is driven power units and methods and systems for activation and by the operating APU engine. The activated load com- 25 deactivation of a load compressor therein. In addition, it pressor in the operating APU supplies the pneumatic is also desirable to provide auxiliary power units in which power for various aircraft systems and functions. These the load compressor therein may be selectively engaged systems and functions may vary, and may include the with and disengaged to the operating APU engine without aircraft environmental control system (ECS), the cabin a friction clutch, thereby resulting in a more lightweight pressure control system, and/or main propulsion engine 30 and less complex APU, lower inertial loading and greater start (MES) air. APU reliability. It is also desirable to provide methods [0003] APU efficiency is generally reported in terms of and systems to selectively disengage the load compres- specific fuel consumption (SFC), the mass of fuel con- sor from the operating APU engine when pneumatic pow- sumed per unit of energy output. Continued operation of er is not needed, thereby improving aircraft fuel economy the load compressor when pneumatic power is not need- 35 and reducing undesirable air emissions and to selectively ed (but the APU is still operating, albeit in "generator- engage with the operating APU engine when pneumatic only mode" to provide electrical power) results in a par- power is needed, thereby maintaining operational flexi- asitic loss of fuel as well as undesirable air emissions. bility. Furthermore, other desirable features and charac- Therefore, it is beneficial to be able to deactivate the load teristics of the present invention will become apparent compressor in the operating APU when pneumatic power 40 from the subsequent detailed description of the invention is not needed, but to be able to (re)activate the load com- and the appended claims, taken in conjunction with the pressor in the operating APU when pneumatic power accompanying drawings and this background of the in- (auxiliary air) is needed. In a typical aircraft, for example, vention. an APU Master Switch is turned to the "Start" position to initiate the APU start and is released to the "Run" position, 45 BRIEF SUMMARY which is the normal operating mode for an "operating APU". When the APU Master Switch is turned to the "Off" [0006] The present invention in its various aspects is position, the auxiliary air is automatically shut off and the as set out in the appended claims. Auxiliary power units APU shuts down. When the APU Master Switch is in the are provided. In accordance with one exemplary embod- "Run" position and an APU Air switch is turned "ON", the 50 iment, the auxiliary power unit includes a load compres- load compressor may be activated to provide com- sor having an impeller, an APU engine, a coupling mem- pressed air (hereinafter "load compressor" or "LC" air) to ber, pre-spinning means, and an APU controller. APU the various aircraft systems and functions. When the engine is adapted to be mechanically engaged to load APU Air switch is turned "Off", the APU air shutoff valve compressor to drive load compressor to provide pneu- closes to isolate the APU from the aircraft pneumatic sys- 55 matic power and to be disengaged when the need for tem, and the load compressor is deactivated to standby pneumatic power ceases. Coupling member couples mode. The APU Master switch turned to the "Off" position load compressor and APU engine and is configured to will shut down the APU regardless of the APU AIR switch be controllably moved between an engaged position in

2 3 EP 2 772 438 B1 4 which the APU engine is mechanically engaged with the preceding background. load compressor, and a disengaged position, in which the APU engine is disengaged from the load compressor. BRIEF DESCRIPTION OF THE DRAWINGS APU controller is operably coupled to load compressor, APU engine, coupling member, and pre-spinning means 5 [0010] The present invention will hereinafter be de- and adapted to receive and be responsive to rotational scribed in conjunction with the following drawing figures, speed signals for controlling movement of coupling mem- whereinlike numerals denote likeelements, andwherein: ber between engaged and disengaged positions. [0007] Methods are provided for activation and deac- FIG. 1 is a simplified schematic diagram of an ex- tivation of a load compressor in an operating auxiliary 10 emplary APU in a system for performing the method power unit (APU) in accordance with yet another exem- of FIG. 4, the encircled region illustrating a load com- plary embodiment of the present invention. The method pressor coupled to a gearbox via a coupler, accord- comprises selectively engaging a load compressor with ing to exemplary embodiments; an APU engine and selectively disengaging the load compressor from the operating APU engine to deactivate 15 FIG. 2A is a sectional view of the load compressor the load compressor. The step of selectively engaging a engaged with the APU engine (more specifically, the load compressor comprises pre-spinning an impeller of load compressor input shaft is engaged with the the load compressor to a rotational speed setpoint with gearbox output shaft via the coupler comprising a compressor discharge bleed air; and mechanically en- clutchless coupling member and a coupling member gaging the load compressor with the operating APU en- 20 actuator) of the exemplary APU of FIG. 1, according gine when a rotational speed of the impeller reaches the to exemplary embodiments; rotational speed setpoint. [0008] Systems are provided for activation and deac- FIG. 2B is a sectional view similar to FIG. 2A, illus- tivation of a load compressor in an operating auxiliary trating the load compressor disengaged from the op- power unit (APU) in accordance with yet another exem- 25 erating APU engine (more specifically, the load com- plary embodiment of the present invention. The system pressor input shaft is disengaged from the gearbox comprises a load compressor in fluid flow communication output shaft), according to exemplary embodiments; with a source of compressor discharge bleed air and adapted to be mechanically engaged with an operating FIG. 3A is a sectional view of the load compressor APU engine when the demand for load compressor (LC) 30 impeller, illustrating tangential impingement of com- air exists and disengaged therefrom when demand there- pressor discharge bleed air through a plurality of in- for ceases. The system further comprises a coupling jection ports; member coupled between the load compressor and the APU engine and configured to be controllably moved be- FIG. 3B is a sectional view of a vaned cascade of tween an engagedposition, in which theload compressor 35 the load compressor impeller (not shown in FIG. 3B); is mechanically engaged with the APU engine, and a disengaged position, in which the APU engine is disen- FIG. 4 is a flow diagram of a method for activation gaged from the load compressor. A bleed control circuit and deactivation of a load compressor in the exem- supplies compressor discharge bleed air to an impeller plary (operating) APU of FIG. 1, according to exem- of the load compressor to pre-spin the impeller to a ro- 40 plary embodiments of the present invention; and tational speed setpoint. An APU controller is operably coupled to the load compressor, the bleed control circuit, FIGS. 5A and 5B are sectional views of the load com- a coupling member actuator, and the APU engine and pressor engaged with (FIG. 5A) and disengaged adapted to receive a first speed signal representative of from (FIG. 5B) the operating APU engine of the ex- a rotational speed of the impeller of the load compressor 45 emplary APU of FIG. 1 (more specifically, the load and a second speed signal representative of a rotational compressor input shaft is illustrated as engaged with speed of the APU engine and configured, in response and disengaged from the gearbox output shaft via thereto, to selectively (i) cause the compressor discharge the coupler comprising a friction clutch and actuator), bleed air to pre-spin the impeller; and (ii) move the cou- according to alternative exemplary embodiments. pling member between the engaged and disengaged po- 50 sitions, the coupling member actuator moving the cou- DETAILED DESCRIPTION pling member to the engaged position when the impeller rotational speed matches the rotational speed setpoint. [0011] The following detailed description is merely ex- [0009] Furthermore, other desirable features and char- emplary in nature and is not intended to limit the invention acteristics of the auxiliary power units and the methods 55 orthe applicationand usesof theinvention. As used here- and systems will become apparent from the subsequent in, the word "exemplary" means "serving as an example, detailed description and the appended claims, taken in instance, or illustration." Thus, any embodiment de- conjunction with the accompanying drawings and the scribed herein as "exemplary" is not necessarily to be

3 5 EP 2 772 438 B1 6 construed as preferred or advantageous over other em- pressed air to the combustor 20. It will be appreciated bodiments. All of the embodiments described herein are that thegas generator compressor 18 maybe implement- exemplary embodiments provided to enable persons ed using any one of numerous types of compressors now skilled in the art to make or use the invention and not to known or developed in the future. For example, the gas limit the scope of the invention which is defined by the 5 generator compressor 18 may be a single-stage or multi- claims. Furthermore, there is no intention to be bound by stage centrifugal compressor. The combustor 20 re- any expressed or implied theory presented in the pre- ceives the compressed air from the gas generator com- ceding technical field, background, brief summary, or the pressor 18, and also receives a flow of fuel from a non- following detailed description. illustrated fuel source via a fuel metering valve (not [0012] Various embodiments are directed to auxiliary 10 shown). The fuel and compressed air are mixed within power units (APUs) and systems and methods for acti- the combustor 20, and are ignited to produce relatively vation and deactivation of a load compressor therein. The high-energy combustion gas. The combustor 20 may be load compressor is adapted to be selectively engaged implemented as any one of numerous types of combus- with an APU engine in the operating APU when the load tors now known or developed in the future. Non-limiting compressor is activated because of a demand for pneu- 15 examples of presently known combustors include vari- matic power and selectively disengaged therefrom when ous can-type combustors, various reverse-flow combus- the load compressor is deactivated because the demand tors, various through-flow combustors, and various slin- for pneumatic power ceases. Engagement of the load ger combustors. No matter the particular combustor con- compressor with the operating APU engine results in the figuration used, the relatively high-energy combustion operating APU engine driving the load compressor to 20 gas that is generated in the combustor is supplied to the supply pneumatic power for various aircraft systems and gas generator turbine 22. As the high-energy combustion functions. As noted above, these systems and functions gas expands through the gas generator turbine 22, it im- may vary, and may include the aircraft environmental pinges on the turbine blades (not shown), causing the control system (ECS), the cabin pressure control system, gas generator turbine 22 to rotate. It will be appreciated and/or main propulsion engine start (MES) air. Selective 25 that the gas generator turbine 22 may be implemented disengagement of the load compressor from the operat- using any one of numerous types of turbines now known ing APU engine when demand for pneumatic power or developed in the future including, for example, a vaned ceases improves aircraft fuel economy, reduces unde- radial turbine, a vaneless radial turbine, and a vaned axial sirable air emissions, and improves APU performance. turbine. No matter the particular type of gas generator The deactivated load compressor is in "standby mode", 30 turbine that is used, the gas generator turbine includes enabling the load compressor to be reactivated quickly a rotatable output shaft 24 that drives the gas generator when the need for pneumatic power exists. When the compressor 18 and the load compressor 14. More spe- load compressor is disengaged from the operating APU cifically, the load compressor may be directly driven by engine, the operating APU provides electrical power only the rotatable output shaft 24 of the APU engine or indi- (i.e., the APU is in generator-only mode). While the var- 35 rectly driven as illustrated, by the gearbox output shaft ious embodiments are described for an aircraft APU, it 25 (FIGS. 1, 2A and 2B, and 5A and B)) (sometimes is to be understood that principles of the inventive subject referred to as a "gearbox-driven load compressor") as matter may be applied to APUs other than aircraft APUs. hereinafter described, both arrangements referred to [0013] Referring now specifically to FIGS. 1 through generally herein as the operating APU engine driving the 5B, according to exemplary embodiments, a simplified 40 load compressor. schematic diagram of an exemplary auxiliary power unit [0014] In the exemplary APU illustrated schematically (APU) 10 in a system for activating and deactivating a in FIGS. 1, 2A through 2B, and 5A through 5B, the gear- load compressor (LC) 14 therein is illustrated. The illus- box 16 couples the APU engine 12 to the combination trated APU 10 comprises an APU engine 12, the load starter/generator 26, that is used for APU starting and compressor (LC) 14, a gearbox 16, and a combination 45 electrical power generation to reduce APU complexity. starter/generator 26. The APU engine 12 comprises a In other non-illustrated APU configurations, the gearbox gas generator compressor 18, a combustor 20, and a 16 may couple the APU engine to a generator, transfer- gas generator turbine 22. The combustor 20 is positioned ring power from the output shaft 24 of the APU engine downstream from the gas generator compressor 18 and to the generator that provides electrical power to the air- the gas generator turbine 22 is coupled coaxially with 50 craft. Within the gearbox 16, power may also be trans- compressor downstream from combustor. The gas gen- ferred to engine accessories (not shown) such as the fuel erator turbine 22 is in flow communication with the com- control unit, the lubrication module, and cooling fan. In bustor 20. The APU engine 12 is the gas generator por- addition, the APU may further include a starter motor (not tion of the engine and produces all the shaft power for shown) connected through the gear train to perform the the APU 10. During operation of the APU engine 12, as 55 APU starting function. is known in the art, the gas generator compressor 18 [0015] The gearbox 16 also couples the APU engine draws ambient air into an inlet thereof (not shown), com- 12 to the load compressor 14 to drive the load compres- presses the air, and supplies a majority of the com- sor to provide pneumatic power. More specifically, as

4 7 EP 2 772 438 B1 8 best illustrated in FIG. 1, the operating APU engine 12 numerous types of compressors now known or devel- drives the rotatable output shaft 24 that is connected by oped in the future. For example, the load compressor a coupling 35 for coupling a load compressor input shaft may be a single-stage or multi-stage centrifugal com- 27 on an opposite side of the gearbox from the APU en- pressor. While the load compressor is illustrated on the gine to the gearbox rotatable output shaft 25. As noted 5 forward side of the gearbox, it is to be understood that previously, the load compressor 14 may alternatively be the load compressor may alternatively be on the engine driven directly by rotatable output shaft 24 without the side of the gearbox. gearbox and gearbox rotatable output shaft 25 (not [0019] The load compressor 14 includes an impeller shown). 28 that includes a plurality of blades 30. Impeller extends [0016] Referring now specifically to FIGS. 2A and 2B, 10 aftward from a compressor inlet 34 and downstream of in an embodiment, the coupling 35 comprises a clutch- a plurality of inlet guide vanes (IGVs) 45 (a single IGV is less coupling member 29 and a coupling member actu- shown for ease of illustration), encompassing the blades ator 31, for purposes as hereinafter described. The cou- and includes an exit 36, a disk 38, and a rotating impeller pling member actuator 31 may be activated electrically shaft 40 extending therebetween. The plurality of inlet (such as by solenoid 33 in FIGS. 2A and 2B), pneumat- 15 guide vanes 45 are disposed adjacent or in the inlet 34 ically, hydraulically, or combinations thereof. The clutch- of the load compressor and are movable, via one or more less coupling member is exemplified by the splined inlet guide vane actuators (not shown), to a plurality of sleeve shown in FIGS. 2A and 2B but other clutchless positions. The inlet guide vane actuators, and thus the coupling members may be used to mechanically engage positions of the inlet guide vanes, are controlled via inlet and disengage the load compressor 14 from the operat- 20 guide vane control logic that is disposed within an APU ing APU engine. The clutchless coupling member does controller 32, as hereinafter described. Impeller 28 is not engage by friction. The illustrated splined sleeve com- bounded by a nonrotating shroud 42 defining its radially prises spline teeth 23 and may be moved via the coupling outer surface. The load compressor extends from the member actuator 31 (exemplified by a simplified repre- inlet 34 to the impeller exit 36 (referred to herein as "an sentation of a conventional fork shifter actuator) to en- 25 exducer 36") in a frusto-conical shape. A flowpath 44 is gage with similar splined teeth on the shaft ends of gear- defined between impeller disk 38 and shroud 42. A dif- box output shaft 25 and LC input shaft 27. fuser 52 is disposed between the impeller exducer 36 [0017] In another embodiment, as illustrated in FIGS. and a diffuser outlet 54. The diffuser is positioned radially 5A and 5B and hereinafter described, the coupling 35 outwardly from the impeller and includes a diffuser inlet comprises a friction clutch 129 and friction clutch actuator 30 and the diffuser outlet 54. Diffuser inlet is adjacent im- 131. Both the clutchless coupling member 29 and the peller exit 36 and inlets air to exit impeller serially into friction clutch 129 are "coupling members" as the term is diffuser 52. The diffuser 52 separates the impeller 28 used herein. The friction clutch comprises a friction clutch from air collection scroll 55. The air collection scroll 55 129 that transmits torque from the gearbox output shaft is in flow communication with diffuser 52 and extends 25 (or the APU engine output shaft 24 with a direct-driven 35 from diffuser outlet 54. Load compressor air (hereinafter load compressor (not shown)) to the LC impeller via a "LC air") exits from the air collection scroll 55 through a clutch plate 132. The clutch plate 132 may be splined via conduit 57 and through an LC air valve (not shown) to a spline 134 to a clutch drive housing 136 that is attached supply pneumatic power for the various aircraft systems to the LC input shaft 27. The clutch plate 132 has friction and functions, such as the ECS, cabin pressure control material (identified as "FM" in FIGS. 5A and 5B) on both 40 system, and/or MES. surfaces to improve slip performance. Two pressure [0020] Still referring to FIGS. 2A through 5B and re- plates, a forward pressure plate and an aft pressure plate turning again to FIG. 1, APU 10 further comprises the 138 and 140, which are part of the gearbox output shaft APU controller 32 that electronically controls the overall 25 straddle the clutch plate 132. Except as specifically operation of the APU as known in the art. The APU con- described below, the method 100 for activation and de- 45 troller 32 is operably coupled to the load compressor, the activation of a load compressor in the exemplary APU APU engine, and a bleed air circuit 37. In accordance 10 is the same, whether the clutchless coupling member with exemplary embodiments, as hereinafter described, 29 or friction clutch 129 couples the load compressor and the APU controller 32 is configured to receive speed sig- the operating APU engine. nals from one or more speed sensors (not shown) that [0018] Referring again to FIGS. 2A through 5B, the 50 represent the rotational speed of the impeller in the load load compressor 14 is generally a shaft-mounted centrif- compressor 14 (more specifically the load compressor ugal compressor that provides pneumatic power for the input shaft 27) and the rotational speed of the APU engine aircraft when the APU 10 is operating (e.g., an APU mas- output shaft 24 or gearbox output shaft 25. The APU con- ter switch (not shown) on the aircraft is in the "Run" po- troller 32, in response to the speed signals, activates the sition) and when the load compressor is activated (e.g., 55 coupling member actuator 31 or 131 as hereinafter de- the APU Air switch (not shown) on the aircraft is in the scribed to move the coupling member 29 or 129 between "ON" position). It should be appreciated that the load engaged and disengaged positions, as hereinafter de- compressor 14 may be implemented using any one of scribed. The APU controller 32 also implements suitable

5 9 EP 2 772 438 B1 10 control logic to control the position of a bleed air valve tominimize the load compressorpumping power, thereby 39 to supply compressor discharge bleed air B to pre- minimizing the required pre-spin bleed airflow. The LC spin the load compressor impeller 28, and inlet guide air valve (not shown) is open to permit delivery of LC air vane actuationlogic tocontrol the positionsof theplurality to various pneumatic loads, as hereinafter discussed. of inlet guide vanes 45, as hereinafter described. A de- 5 The load compressor impeller 28 is pre-spun by the com- tailed description of the various control logic used to con- pressor discharge bleed air portion B from zero speed trol the operation of the APU is not needed to fully de- (the load compressor in this case having been in standby scribe or enable the claimed invention, and will therefore mode) to the rotational speed setpoint to permit mechan- not be provided. ical engagement of the load compressor with the oper- [0021] Still referring to FIGS. 1 through 3B, and 5A10 ating APU engine (more specifically, engagement of the through 5B and referring now to FIG. 4, according to ex- load compressor input shaft 27 to either the APU engine emplary embodiments, a method 100 for activating and output shaft 24 (direct drive) or the gearbox output shaft deactivating a load compressor in an operating APU be- 25) as hereinafter described. More specifically, a portion gins by determining that there is a demand for pneumatic of the high pressure compressor discharge (P3) bleed power (step150). The APU controller32 (FIG. 1) receives 15 air B is taken from the P3 bleed air section as noted pre- a signal that the load compressor 14 should be activated viously, and transferred to the pre-spin inlet manifold 47 (such as when an APU Air switch (not shown) has been on the load compressor shroud 42 near the exducer 36. switched by aircraft personnel to the "ON" position) so The term "high pressure" as used herein refers to a pres- as to provide pneumatic power to the aircraft. The APU sure greater than about 50 psia. FIG. 3A illustrates the controller 32 responds by automatically activating the 20 high pressure compressor discharge bleed air portion B load compressor 14 as hereinafter described. injected tangentially through injection ports 51 (a single [0022] The load compressor is activated by first pre- injection port 51 is shown in FIGS. 2A and 2B and FIGS. spinning the impeller 28 of the load compressor 14 to a 5A and 5B for ease of illustration) or through the vaned rotational speed setpoint with a portion of the compressor cascade 53 (FIG. 3B) near the exducer, and impinges discharge bleed air B (step 200). The compressor dis- 25 on the impeller blade tips. Multiple injection ports (e.g., charge bleed air B or simply "bleed air" is supplied from greater than two) provide flow and torque balance. The a P3 bleed air section (downstream of the gas generator one or more injection points 51 are set at as high a radius compressor 18) of the operating APU engine 12. The on theimpeller as possible, but not higher thanthe limiting "P3" bleed air section is well known to one skilled in the radius. The limiting radius is defined as the point where art. As noted previously, a majority of the compressor 30 the impeller speed exceeds the injection tangential jet discharge air is mixed with fuel and burned in the com- velocity at 100% load compressor rotor RPM. The pre- bustor 20 to generate the gas that drives the gas gener- spin bleed air impinges on the impeller blades at the high ator turbine 22. A smaller portion of the compressor dis- radius. Pre-spinning of the impeller comprises contacting charge bleed air is directed through the bleed air circuit a circumferential surface of the impeller with the high 37 to pre-spin the load compressor impeller in accord- 35 pressure compressor discharge bleed air portion B from ance with exemplary embodiments. In accordance with the gas generator compressor 18, causing the load com- exemplary embodiments, the load compressor 14 in fluid pressor impeller to pre-spin at an impeller rotational flow communication with the gas generator compressor speed to eliminate (in the case of clutchless coupling 18, the source of the high pressure compressor dis- member 29) or minimize (in the case of friction clutch charge bleed air B. 40 129) the speed differential between output shaft 24 or 25 [0023] The bleed air circuit 37 has a bleed air circuit and LC impeller input shaft 27, as hereinafter described. inlet 41 and an outlet 43 (FIG. 1). The bleed air circuit [0024] Referring again to FIGS. 2A and 4, according inlet 41 is coupled to receive the compressor discharge to exemplary embodiments, method 100 for activating bleed air portion that is used to pre-spin the impeller, and and deactivating the load compressor in the operating the outlet 43 is coupled to supply the compressor dis- 45 APU continues by mechanically engaging the load com- charge bleed air portion to pre-spin the load compressor pressor with theoperating APU engine(more specifically, impeller. The bleed air circuit additionally includes the the load compressor input shaft 27 is coupled or engaged bleed air valve 39 operably disposed in the bleed air cir- with the output shaft 24 of the operating APU engine (di- cuit upstream of the load compressor 14. The bleed air rect drive) or the gearbox output shaft 25 (FIGS. 2A)) valve 39 is used to modulate or shut off and turn on the 50 when the LC impeller (more specifically the LC input shaft flow of compressor discharge bleed air B for selectively 27) rotational speed reaches the rotational speed set- directing the compressor discharge bleed air portion B point (step 250). As noted above, pneumatic power is into the load compressor 14 through the plurality of in- provided to the aircraft by the activated and engaged load jection ports 51 (FIG. 3A) or through a vaned cascade compressor. The combination of steps 200 and 250 se- 53 (FIG. 3B) near the LC impeller exducer 36. During the 55 lectively engage the load compressor with the operating pre-spinning step, the bleed air valve 39 and a pre-spin APU engine. The rotational speed setpoint is the rota- inlet manifold 47 are open and the plurality of inlet guide tional speed at which the impeller rotational speed match- vanes 45 to the load compressor are substantially closed es a predetermined percentage of the rotational speed

6 11 EP 2 772 438 B1 12 of the output shaft. In the case of the clutchless coupling tions may be regulated. As noted above, LC air may be member 29 and actuator 31 (FIG. 2A), the predetermined supplied to the various aircraft systems and functions percentage is 100%, i.e., the rotational speed setpoint is (also referred to herein as "pneumatic loads") via the LC the rotational speed at which the impeller rotational air valve (not shown) in the "open" position. For ease of speed matches (100%) the rotational speed of the output 5 illustration, the pneumatic loads are not illustrated, but shaft. In this case, pre-spinning the load compressor im- may include, for example, an environmental control sys- pellereliminates the rotationalspeed differential between tem (ECS), cabin pressure control system, and main en- the LC input shaft 27 and the output shaft 24 or 25 being gine starting (MES) air for one or more main propulsion driven by the APU engine, enabling mechanical engage- engines. ment of the load compressor with the operating APU en- 10 [0027] Referring again to FIGS. 2B and 4, the method gine, as hereinafter described. 100 for activating and deactivating a load compressor in [0025] The speed sensor (not shown) on the load com- an operating APU continues by selectively disengaging pressor 14 provides the triggering point for engagement. the load compressor from the operating APU engine The speed sensor monitors the LC impeller rotational when demand for pneumatic power ceases (step 300). speed and the rotational speed of the output shaft 24 or 15 The load compressor is disengaged from the operating 25. APU controller 32 is configured to receive a first speed APU engine upon load compressor deactivation. Deac- signal representative of the impeller rotational speed and tivation may be initiated by, for example, aircraft person- a second speed signal representative of the rotational nel switching the APU air switch to the "Off" position. As speed of the APU engine (more specifically, the rotational noted above, the engaged load compressor provides speed of the APU engine output shaft 24 or gearbox out- 20 pneumatic power (also known as auxiliary air) to the air- put shaft 25, depending on whether a direct driven or craft when the main propulsion engine(s) are not running. gearbox-driven compressor is used). The APU controller However, continued operation of the load compressor is further configured to automatically activate the cou- whenpneumatic power isnot needed results in a parasitic pling member actuator 31 based on a comparison of the loss of fuel and contributes to undesirable air emissions. first and second speed signals. The coupling actuator 31 25 Therefore, it is beneficial to be able to deactivate the load is automatically activated if the LC impeller rotational compressor and selectively disengage the load compres- speed matches (100%) the preset percentage of the ro- sor from the operating APU engine when the demand for tational speed of the output shaft. The activated actuator pneumatic power ceases, thereby improving aircraft fuel moves the clutchless coupling member 29 to an engaged economy and APU performance. As noted above, when position (as shown respectively in FIGS. 2A and 5A)30 the load compressor is disengaged from the operating thereby engaging the load compressor 14 with the oper- APU engine, the APU provides electrical power only (i.e., ating APU engine 12 such that the operating APU engine the APU is in generator-only mode). 12 (more specifically, the output shaft 24 or 25) may drive [0028] When a signal is received by the APU controller the load compressor 14 to supply compressed LC air to to deactivate the load compressor to standby mode (such the various aircraft systems and functions. Thus, clutch- 35 as when the APU air switch is set to the "off" position), less coupling members 29 may be controlled to selec- the APU controller automatically activates the actuator tively engage (and disengage as hereinafter described) 31 to move the clutchless coupling member 29 to a dis- the load compressor input shaft 27 with the rotatable out- engaged position (FIG. 2B) whereby the deactivated load put shaft 24 or 25 when the load compressor impeller is compressor and the operating APU engine are disen- pre-spun to match the preset percentage of the rotational 40 gaged. In the illustrated gearbox-driven load compressor speed of the output shaft 24 or 25. If a signal loss occurs of FIG. 2B, disengagement is via moving the splined in the load compressor speed sensor, the actuation sleeve off the splined gearbox output shaft 25 to the rest- sourced power is disabled to prevent uncontrolled en- ing position on the splined LC input shaft 27. Disengage- gagement, i.e., the APU controller 32 will prevent the ment is accomplished by command from the APU con- clutchless coupling member 29 from engaging. 45 troller 32 (FIG. 1) to first apply a disengaging force via [0026] When the load compressor 14 is activated, as the actuator 31 and then to simultaneously command a known in the art, the load compressor draws ambient air momentary gas generator power reduction and substan- into the pre-spin inlet manifold via the plurality of inlet tial closing of the plurality of inlet guide vanes 45, causing guide vanes 45 in the "open" position, and compresses the torque acting through the splined drive couplings to the air. As the inlet guide vanes start to substantially50 go to zero. When the torque drops to a sufficiently low close, they change the gas entry angle to the impeller value before reaching zero, the actuator 31 will move the and reduce gas flow and load compressor capacity. As coupler to its resting position on the splined load com- is generally known, by selectively adjusting the position pressor input shaft 27. The disengaging force can be of the inlet guide vanes, the flow rate of air (both com- active or passive. As used herein, the term "active" pressor discharge bleed air and ambient air) entering the 55 means a double-acting solenoid 33 in the case of an elec- load compressor, and thus the flow rate of compressed trically driven actuator 31. The term "passive" as used air (hereinafter referred to as "load controller air" or "LC herein means a single-acting solenoid 33 with a spring air") supplied to the various aircraft systems and func- preload. The illustrated exemplary splined sleeve rests

7 13 EP 2 772 438 B1 14 on the splined load compressor input shaft when the load In addition, the pre-spinning step increases clutch life compressor is deactivated. and overall friction clutch reliability. [0029] Referring now specifically to FIGS. 5A and 5B, [0031] With the gearbox-driven load compressor (as in accordance with an alternative embodiment and as illustrated in FIGS. 5A and 5B), the friction clutch 129 noted previously, the coupling 35 (FIG. 1) may comprise 5 transmits torque from the gearbox output shaft 25 to the a friction clutch 129 and friction clutch actuator 131 which LC impeller via the clutch plate 132. The clutch plate 132 operate in a conventional manner, and therefore will not may be splined via the spline 134 to the clutch drive hous- be described in detail. While a gearbox-driven compres- ing 136 that is attached to the LC input shaft 27. The sor is illustrated in FIGS. 5A and 5B, it is to be understood clutch plate 132 friction material (identified as "FM" in that the load compressor may alternatively be directly 10 FIGS. 5A and 5B) on both surfaces improves slip per- driven by output shaft 24 as previously described. The formance. As noted previously, two pressure plates, a pre-spinning and mechanically engaging steps (200 and forward pressure plate and an aft pressure plate 138 and 250)to engage theload compressor tothe operatingAPU 140, which are part of the gearbox output shaft 25 strad- engine are generally the same as previously described, dle the clutch plate 132. When pneumatic power is need- with the exceptions as noted below. Pre-spinning the im- 15 ed (i.e., the load compressor is to be engaged), the APU peller of the load compressor to a preset percentage of controller 32 commands the actuator 131 to move the the rotational speed setpoint with a portion of the com- friction clutch (a "coupling member") between the en- pressor discharge bleed air B (step 200) according to gaged and disengaged position (more specifically, the exemplary embodiments reduces the wear, and increas- APU controller 32 commands the actuator 131 to move es clutch life and overall reliability of the otherwise failure- 20 a pressure plate carrier assembly 142 (shown attached prone friction clutch. The relative speed differential be- to aft pressure plate 140) of the friction clutch toward the tween the gearbox output shaft 25 and the LC drive shaft clutch plate 132). This movement clamps the clutch plate 27 is reduced (as opposed to eliminated when using the 132 between the forward and aft pressure plates 138 and clutchless coupling member) by pre-spinning the LC im- 140, resulting in clutch engagement and engagement of peller prior to friction clutch engagement. When pre-spin- 25 the load compressor with the operating APU engine ning the impeller and using a friction clutch, the rotational (more specifically engagement between the impeller in- speed setpoint for the pre-spun impeller may be from put shaft 27 and the gearbox output shaft 25). The acti- about 50% to about 90% of the rotational speed of the vated actuator moves the pressure plate carrier assem- output shaft 24 or 25 before engagement of the friction bly 142 to an engaged position (as shown in FIG. 5A) clutch. The pre-spinning step also minimizes the amount 30 thereby engaging the load compressor 14 with the oper- of bleed air usage in situations where the gas generator ating APU engine 12 such that the operating APU engine compressor has insufficient surge margin to accommo- 12 (more specifically, the output shaft) may drive the load date the relatively large bleed flow required to pre-spin compressor 14 to supply compressed LC air to the var- the impeller to the rotational speed setpoint. ious aircraft systems and functions. When the load com- [0030] Friction clutches without the pre-spinning step 35 pressor is disengaged (step 300) as illustrated in FIG. are failure prone when used to engage and disengage a 5B, the LC impeller and clutch plate are not rotating, while load compressor from an operating APU because, while the gearbox output shaft 25 and the pressure plates are sufficient pressure is maintained by the pressure plate rotating. There is a small gap between the clutch plate carrier assembly 142 to prevent slippage at steady state and the pressure plates such that no load is transmitted conditions, very high slip rates occur during transient40 to the load compressor impeller. clutch engagement, especially during initial contact be- [0032] Steps 200, 250, and 300 may be repeated as tween the friction material (FM) and the pressure plates. many times as necessary as the demand for APU pneu- The friction clutch undergoes transient slip between the matic power changes. While performance of steps 200 driving pressure plates attached to the gearbox output and 250 prior to step 300 has been described, it is to be shaft 25 and the driven clutch plate attached to the LC 45 understood that step 300 may alternatively be performed impeller. The LC impeller can accelerate quickly from prior to steps 200 and 250 depending upon whether the zero speed to 100% gearbox output shaft speed in a few load compressor is already activated or already deacti- seconds, resulting in high temperature rise and high wear vated. of the friction material. The transient loading can also [0033] It is to be appreciated that systems and methods result in high inertial forces and vibration, reducing clutch 50 have been provided for activation and deactivation of a life. The slip condition is most severe at initial clutch en- load compressor in an operating APU. The activated load gagement as the relative speed differential between the compressor is selectively engaged with the operating stationary clutch plate and the rotating pressure plates APU engine when pneumatic power is needed, thereby is 100%, resulting in high wear and reduced life of the maintaining operationalflexibility and engagement iswith friction clutch. By pre-spinning the impeller, a conven- 55 lower inertial loading thereby improving APU perform- tional friction clutch as known in the art may be used, but ance. The deactivated load compressor is selectively dis- the friction clutch may be smaller, lighter, and simpler engaged from the operating APU engine when pneumat- thanthe frictionclutch usedwhen no pre-spinning occurs. ic power is not needed, thereby improving aircraft fuel

8 15 EP 2 772 438 B1 16 economy and reducing undesirable air emissions. ond speed signals to activate the actuator to move [0034] While at least one exemplary embodiment has the coupling member (29) to the engaged position been presented in the foregoing detailed description of upon the rotational speed of the impeller (28) reach- the invention, it should be appreciated that a vast number ing the rotational speed setpoint. of variations exist. It should also be appreciated that the 5 exemplary embodiment or exemplary embodiments are 3. The auxiliary power unit of Claim 1, wherein the load only examples, and are not intended to limit the scope, compressor further comprises a plurality of inlet applicability, or configuration of the invention in any way. guide vanes (45) at an inlet thereof and movable Rather, the foregoing detailed description will provide between positions substantially opening and sub- those skilled in the art with a convenient road map for 10 stantially closing the inlet wherein , if the rotational implementing an exemplary embodiment of the inven- speed setpoint is reached, the APU controller (32) tion. It being understood that various changes may be is further responsive, to: made in the function and arrangement of elements de- scribed in an exemplary embodiment without departing modulate the plurality of inlet guide vanes (45) from the scope of the invention as set forth in the ap- 15 substantially open; and pended claims and their legal equivalents. open a load compressor bleed valve.

4. The auxiliary power unit of Claim 1, wherein the APU Claims engine comprises a gas generator compressor, a 20 combustor,and a gasgenerator turbine, and wherein 1. An auxiliary power unit (APU) comprising: the pre-spinning means comprises a bleed air circuit (37) adapted to supply compressor discharge bleed a load compressor (14) having an impeller (28); airto pre-spin the impeller(28) to the rotationalspeed an APU engine adapted to be mechanically en- setpoint, the gas generator compressor adapted to gaged to the load compressor (14) to drive the 25 provide the compressor discharge bleed air in the loadcompressor (14) to providepneumatic pow- bleed air circuit (37) causing the impeller (28) to pre- er and to be disengaged therefrom when the spin to the rotational speed setpoint, the rotational need for pneumatic power ceases; speed setpoint comprising the rotational speed at a coupling member (29) coupled between the which the impeller (28) rotational speed matches a load compressor and APU engine and config- 30 predetermined percentage of the rotational speed of ured to be controllably moved between an en- an APU engine output shaft or gearbox output shaft. gaged position, in which the APU engine is me- chanically engaged with the load compressor 5. The auxiliary power unit of Claim 4, wherein the cou- (14), and a disengaged position, in which the pling member (29) comprises one of a clutchess cou- APU engine is disengaged from the load com- 35 pling member (29) or a friction clutch, and if the cou- pressor (14); pling member (29) comprises a clutchless coupling characterised in further comprising; member (29), the predetermined percentage is pre-spinning means coupled to the load com- 100%. pressor (14) and configured to selectively pre- spin the impeller (28); and 40 6. A method (100) for activating and deactivating a load an APU controller (32) operably coupled to the compressor (14) in an operating auxiliary power unit load compressor (14), the APU engine, the cou- (APU) comprising an APU engine and a load com- pling member (29), and the pre-spinning means, pressor, the method comprising: the APU controller (32) adapted to receive rota- tional speed signals and configured, in response 45 selectively engaging the load compressor with thereto, to (i) selectively cause the pre-spinning the APU engine to activate the load compressor means to pre-spin the impeller (28) to a rotation- characterised by: al speed setpoint; and (ii) selectively move the coupling member (29) between the engaged pre-spinning an impeller (28) of the load and disengaged positions. 50 compressor to a rotational speed setpoint with compressor discharge bleed air (200); 2. The auxiliary power unit of Claim 1, wherein the APU and controller (32) receives the rotational speed signals mechanically engaging the load compres- comprising a first speed signal representative of a sor (14) with the APU engine when a rota- rotational speed of the impeller (28) of the load com- 55 tional speed of the impeller (28) reaches the pressor (14) and a second speed signal represent- rotational speed setpoint (250); and ative of a rotational speed of the APU engine, the APU controller (32) responsive to the first and sec- selectively disengaging the load compressor

9 17 EP 2 772 438 B1 18

(14) from the operating APU engine to deacti- activating the actuator to move the clutchless vate the load compressor (300). coupling member (29) to the engaged position when the speed signal value of the impeller (28) 7. The method of Claim 6, wherein the APU engine matches the APU engine speed signal value comprises a gas generator compressor, the step 5 such that the operating APU engine is engaged (200 and 250) of selectively engaging the load com- with and drives the load compressor to provide pressorwith the APU enginefurther comprises open- pneumatic power. ing a bleed air valve (39) disposed between the gas generator compressor and the load compressor and 13. A system for activating and deactivating a load com- a pre-spin inlet manifold such that compressor dis- 10 pressor (14) in an operating auxiliary power unit charge bleed air flows into the impeller (28). (APU) including an APU engine, the system com- prising: 8. The method of Claim 6, wherein the step (200) of pre-spinning the impeller (28) to the rotational speed the load compressor in fluid flow communication setpoint comprises contacting a circumferential sur- 15 with a source of compressor discharge bleed air face of the load compressor impeller (28) with high and adapted to be mechanically engaged with pressure compressor discharge bleed air. the APU engine when the demand for load com- pressor (14) exists and disengaged therefrom 9. The method of Claim 6, wherein a coupling member when demand therefor ceases; (29) is coupled between the load compressor and 20 a coupling member (29) coupled between the APU engine, the coupling member (29) comprising load compressor and the APU engine and con- one of a clutchess coupling member (29) or a friction figured to be controllably moved between an en- clutch, and the step (250) of mechanically engaging gaged position, in which the load compressor is the load compressor with the operating APU engine mechanically engaged with the APU engine, comprises activating an actuator to move the cou- 25 and a disengaged position, in which the APU pling member (29) to an engaged position. engine is disengaged from the load compressor (14); 10. The method of Claim 9, wherein the step (200) of characterised by further comprising; pre-spinning the impeller (28) to the rotational speed a bleed control circuit for supplying the compres- setpoint comprises pre-spinning the impeller (28) to 30 sor discharge bleed air to an impeller (28) of the a rotational speed that is 100% of the rotational load compressor to pre-spin the impeller (28) to speed of the APU engine when the coupling member a rotational speed setpoint; (29) comprises the clutchless coupling member (29). an APU controller (32) operably coupled to the load compressor (14), the bleed control circuit, 11. The method of Claim 7, wherein the step (300) of 35 a coupling member (29) actuator, and the APU selectively disengaging the load compressor from engine and adapted to receive a first speed sig- the operating APU engine comprises: nal representative of a rotational speed of the impeller (28) of the load compressor and a sec- modulating a plurality of inlet guide vanes (45) ond speed signal representative of a rotational substantially closed to discontinue the flow of 40 speed of the APU engine and configured, in re- compressor discharge bleed air into the impeller sponse thereto, to selectively (i) cause the com- (28); and pressor discharge bleed air to pre-spin the im- providing a momentary gas generator power re- peller (28); and (ii) move the coupling member duction. (29) between the engaged and disengaged po- 45 sitions, the coupling member (29) actuator mov- 12. The method of Claim 9, wherein the step (200 and ing the coupling member (29) to the engaged 250) of mechanically engaging the load compressor position when the impeller (28) rotational speed with the APU engine when a rotational speed of the matches the rotational speed setpoint. impeller (28) reaches the rotational speed setpoint comprises: 50 14. The system of Claim 13, wherein the bleed air circuit (37) has a bleed air circuit (37) inlet and an outlet, determining a speed signal value of the impeller the bleed air circuit (37) inlet adapted to receive the (28); compressor discharge bleed air and the outlet adapt- determining a speed signal value of the APU ed to supply the compressor discharge bleed air to engine; 55 pre-spin the impeller (28), the bleed air circuit (37) comparing the speed signal value of the impeller including a bleed control valve operably disposed in (28) against the speed signal value of the APU the bleed air circuit (37) upstream of the load com- engine; and pressor for modulating or shutting off and turning on

10 19 EP 2 772 438 B1 20

the flow of compressor discharge bleed air to the dichter ferner eine Mehrzahl von Einlass-Leitschau- load compressor (14). feln (45) an einem Einlass davon umfasst und zwi- schen Positionen beweglich ist, die im Wesentlichen 15. The system of Claim 13, wherein the APU controller den Einlass öffnen und schließen, wobei, wenn der (32) is configured to activate the coupling member 5 Drehzahl-Sollwert erreicht wird, die APU-Steuerung (29) actuator based on a comparison of the first and (32) ferner reagiert, um: second speed signals, the coupling member (29) ac- tuator activated if the rotational speed setpoint is die Mehrzahl von Einlassleitschaufeln (45) im reached. Wesentlichen zu offen zu stellen; und 10 ein Lastverdichter-Entlüftungsventil zu öffnen.

Patentansprüche 4. Hilfskraftquelle nach Anspruch 1, wobei der APU- Motor einen Gaserzeugerverdichter, einen Brenner 1. Hilfskraftquelle (APU), umfassend: einen Lastver- und eine Gaserzeugerturbine umfasst, wobei das dichter (14) mit einem Laufrad (28); 15 Vorspinnmittel einen Entlüftungsluftkreislauf (37) einen APU-Motor, der zum mechanischen Einrü- umfasst, der zum Zuführen von Verdichterablass- cken mit dem Lastverdichter (14) zum Antreiben des Entlüftungsluft zum Vorspinnen des Laufrads (28) Lastverdichters (14) zum Bereitstellen von pneuma- zum Drehzahl-Sollwert ausgelegt ist, wobei der tischer Leistung und zum Ausrücken davon, wenn Gaserzeugerverdichter zum Bereitstellen der Ver- der Bedarf an einer pneumatischen Leistung endet, 20 dichterauslass-Entlüftungsluft in den Entlüftungs- ausgelegt ist; luftkreislauf (37) ausgelegt ist, wodurch das Laufrad ein Kopplungselement (29), das zwischen dem Last- (28) zum Drehzahl-Sollwert vorspinnt, wobei der verdichter und APU-Motor gekoppelt ist und gesteu- Drehzahlsollwert die Drehzahl umfasst, bei der die ert zwischen einer Einrückposition, bei der der APU- Drehzahl des Laufrads (28) einem vorbestimmten Motor mechanisch in den Lastverdichter (14) ein- 25 Prozentsatz der Drehzahl der APU-Motors-Aus- rückt, und einer Ausrückposition, bei der der APU- gangswelle oder Getriebeausgangswelle entspricht. Motor aus dem Lastverdichter (14) ausgerückt wird, beweglich ist; gekennzeichnet dadurch, dass sie 5. Hilfskraftquelle nach Anspruch 4, wobei das Kopp- ferner umfasst: lungselement (29) entweder ein Kopplungselement 30 ohne Kupplungsscheibe (29) oder eine Reibungs- Vorspinnmittel, die mit dem Lastverdichter (14) kupplung umfasst, und der Prozentsatz, wenn das gekoppelt sind und zum selektiven Vorspinnen Kopplungselement (29) ein Kopplungselement (29) des Laufrads (28) konfiguriert sind; und ohne Kupplungsscheibe umfasst, 100 % beträgt. eine APU-Steuerung (32),die betriebswirksam mit dem Lastverdichter (14), dem APU-Motor, 35 6. Verfahren (100) zum Ein- und Ausschalten eines dem Kopplungselement (29) und dem Vorspinn- Lastverdichters (14) in einer betriebenen Hilfskraft- mittel verbunden ist, wobei die APU-Steuerung quelle (APU), die einen APU-Motor und einen Last- (32) zum Aufnehmen von Drehzahlsignalen verdichter umfasst, wobei das Verfahren umfasst: ausgelegt ist und als Reaktion darauf konfigu- riert ist, um (i) das Vorspinnmittel selektiv zum 40 selektives Einrücken des Lastverdichters in den Vorspinnen des Laufrads (28) bis zu einem APU-Motor, um den Lastverdichter einzuschal- Drehzahl-Sollwert zu veranlassen; und (ii) das ten, gekennzeichnet durch: Kopplungselement (29) selektiv zwischen Ein- rück- und Ausrückposition zu bewegen. Vorspinnen eines Laufrads (28) des Last- 45 verdichters zu einem Drehzahl-Sollwert mit 2. Hilfskraftquelle nach Anspruch 1, wobei die APU- einer Verdichterauslass-Entlüftungsluft Steuerung (32) die Drehzahlsignale empfängt, die (200); und ein erstes Drehzahlsignal umfassen, das für eine mechanisches Einrücken des Lastverdich- Drehzahl des Laufrads (28) des Lastverdichters (14) ters (14) in den APU-Motor, wenn eine steht, und ein zweites Drehzahlsignal, das für eine 50 Drehzahl des Laufrads (28) den Drehzahl- Drehzahl des APU-Motors steht, wobei die APU- Sollwert (250) erreicht; und Steuerung (32) auf das erste und das zweite Dreh- selektives Ausrücken des Lastverdichters zahlsignal reagiert, um das Stellglied zu aktivieren, (14) aus dem APU-Motor, um den Lastver- um das Kopplungselement (29) zu der Einrückposi- dichter (300) auszuschalten. tion zu bewegen, wenn die Drehzahl des Laufrads 55 (28) den Drehzahl-Sollwert erreicht. 7. Verfahren nach Anspruch 6, wobei der APU-Motor einen Gaserzeugerverdichter umfasst, wobei der 3. Hilfskraftquelle nach Anspruch 1, wobei der Lastver- Schritt (200 und 250) des selektiven Einrückens des

11 21 EP 2 772 438 B1 22

Lastverdichters mit dem APU-Motor ferner das Öff- Einschalten des Stellglieds zum Bewegen des nen eines Entlüftungsventils (39), das zwischen dem Kopplungselements (29) ohne Kupplungsschei- Gaserzeugerverdichter und dem Lastverdichter an- be zu der eingerückten Position, wenn der Dreh- geordnet ist, und ein Vorspinnen des Einlasskrüm- zahlsignalwert des Laufrads (28) mit dem APU- mers umfasst, sodass Verdichterablass-Entlüf-5 Motor-Drehzahlsignalwert übereinstimmt, so- tungsluft in das Laufrad (28) strömt. dass der betriebene APU-Motor mit dem Last- verdichter eingerückt ist und diesen antreibt, um 8. Verfahren nach Anspruch 6, wobei der Schritt (200) eine pneumatische Leistung bereitzustellen. des Vorspinnens des Laufrads (28) auf den Dreh- zahl-Sollwert das Inkontaktbringen einer Umfangs- 10 13. System zum Ein- und Ausschalten eines Lastver- fläche des Lastverdichter-Laufrads (28) mit einer dichters (14) in einer betriebenen Hilfskraftquelle Hochdruck-Verdichterablass-Entlüftungsluft um- (APU), die einen APU-Motor aufweist, wobei das fasst. System umfasst:

9. Verfahren nach Anspruch 6, wobei ein Kopplungs- 15 den Lastverdichter in Fluidströmungsverbin- element (29) zwischen dem Lastverdichter und dem dung mit einer Quelle der Verdichterauslass- APU-Motor gekoppelt ist, wobei das Kopplungsele- Entlüftungsluft, der zum mechanischen Einrü- ment (29) ein Kopplungselement (29) ohne Kupp- cken in den APU-Motor ausgelegt ist, wenn ein lungsscheibe oder eine Reibungskupplung aufweist, Bedarf an dem Lastverdichter (14) besteht, und und wobei der Schritt (250) des mechanischen Ein- 20 davon ausgerückt wird, wenn der Bedarf daran rückens des Lastverdichters mit dem betriebenen endet; APU-Motor das Einschalten eines Stellglieds zum ein Kopplungselement (29), das zwischen dem Bewegen des Kopplungselements (29) zu der Ein- Lastverdichter undAPU-Motor gekoppelt ist und rückposition umfasst. gesteuert zwischen einer Einrückposition, bei 25 der der Lastverdichter mechanisch in den APU- 10. Verfahren nach Anspruch 9, wobei der Schritt (200) Motor einrückt, und einer Ausrückposition, bei des Vorspinnens des Laufrads (28) zum Drehzahl- der der APU-Motor aus dem Lastverdichter (14) Sollwert das Vorspinnen des Laufrads (28) zu einer ausgerückt ist, beweglich ist; Drehzahl umfasst, die 100 % der Drehzahl des APU- gekennzeichnet dadurch, dass es ferner um- Motors entspricht, wenn das Kopplungselement (29) 30 fasst: das Kopplungselement (29) ohne Kupplungsschei- be umfasst. einen Entlüftungssteuerkreislauf zum Zu- führen der Verdichterablass-Entlüftungsluft 11. Verfahren nach Anspruch 7, wobei der Schritt (300) zum einem Laufrad (28) des Lastverdich- des selektiven Ausrückens des Lastverdichters aus 35 ters zum Vorspinnen des Laufrads (28) zu dem betriebenen APU-Motor umfasst: einem Drehzahl-Sollwert; eine APU-Steuerung (32), die betriebswirk- Aussteuern einer Mehrzahl von Einlass-Leit- sam mit dem Lastverdichter (14), dem Ent- schaufeln (45), die im Wesentlichen geschlos- lüftungssteuerkreis, einem Kopplungsele- sen sind, um die Strömung von Verdichterab- 40 ment-Stellglied (29) und dem APU-Motor lass-Entlüftungsluft in das Laufrad (28) zu un- gekoppelt ist und zum Aufnehmen eines terbrechen; und ersten Drehzahlsignals, das für eine Dreh- Bereitstellen einer momentanen Gaserzeuger- zahl des Laufrads (28) des Lastverdichters Leistungsreduzierung. steht, und eines zweiten Drehzahlsignals, 45 das für eine Drehzahl des APU-Motors 12. Verfahren nach Anspruch 9, wobei der Schritt (200 steht, ausgelegt ist und konfiguriert ist, um und 250) des mechanischen Einrückens des Last- als Reaktion darauf verdichters in den APU-Motor, wenn eine Drehzahl des Laufrads (28) den Drehzahl-Sollwert erreicht, (i) selektiv zu veranlassen, dass Ver- umfasst: 50 dichterablass-Entlüftungsluft das Lauf- rad (28) vorspinnt; und Bestimmen eines Drehzahl-Signalwerts des (ii) das Kopplungselement (29) zwi- Laufrades (28) ; schen der Einrück- und der Ausrückpo- Bestimmen eines Drehzahl-Signalwerts des sition zu bewegen, wobei das Kopp- APU-Motors; 55 lungselement-Stellglied (29) das Kopp- Vergleichen des Drehzahl-Signalwerts des lungselement (29) zu der Einrückposi- Laufrades (28) mit dem Drehzahlsignalwert des tion bewegt, wenn die Laufrad-Dreh- APU-Motors; und zahl (28) mit dem Drehzahl-Sollwert

12 23 EP 2 772 438 B1 24

übereinstimmt. (32) étant prévu pour recevoir des signaux de vitesse de rotation et étant configuré, en 14. System nach Anspruch 13, wobei der Entlüftungs- réponse à ceux-ci, pour (i) amener de ma- luftkreislauf (37) einen Entlüftungsluftkreislauf-Ein- nière sélective le moyen de pré-rotation à lass und -Auslass aufweist, wobei der Einlass des 5 effectuer la pré-rotation du rotor (28) à une Entlüftungsluftkreislaufs (37) zum Aufnehmen der vitesse de rotation de consigne ; et (ii) dé- Verdichterablass-Entlüftungsluft ausgelegt ist und placer de manière sélective l’organe d’ac- der Auslass zum Zuführen der Verdichterablass- couplement (29) entre les positions enga- Entlüftungsluft zum Vorspinnen des Laufrads (28) gée et désengagée. ausgelegt ist, wobei der Entlüftungsluftkreislauf (37) 10 ein Entlüftungsventil aufweist, das betriebswirksam 2. Unité de puissance auxiliaire selon la revendication in dem Entlüftungsluftkreislauf (37) stromaufwärts 1, dans laquelle le dispositif de commande d’UPA des Lastverdichters angeordnet ist, um die Strö- (32) reçoit les signaux de vitesse de rotation com- mung von Verdichterablass-Entlüftungsluft zum prenant un premier signal de vitesse représentatif Lastverdichter (14) einzustellen oder auszuschalten 15 d’une vitesse de rotation du rotor (28) du compres- oder einzuschalten. seur de charge (14) et un deuxième signal de vitesse représentatif d’une vitesse de rotation du moteur 15. System nach Anspruch 13, wobei die APU-Steue- d’UPA, le dispositif de commande d’UPA (32) réa- rung (32) zum Betätigen des Kupplungselement- gissant au premier et au deuxième signal de vitesse Stellglieds (29) basierend auf einem Vergleich des 20 pour activer l’actionneur de manière à déplacer l’or- ersten und des zweiten Drehzahlsignals konfiguriert gane d’accouplement (29) dans la position engagée ist, wobei das Kopplungselement-Stellglied (29) ein- lorsque la vitesse de rotation du rotor (28) atteint la geschaltet wird, wenn der Drehzahlsollwert erreicht vitesse de rotation de consigne. wird. 25 3. Unité de puissance auxiliaire selon la revendication 1, dans laquelle le compresseur de charge com- Revendications prend en outre une pluralité d’ailettes de guidage d’entrée (45) au niveau d’une entrée de celui-ci, les- 1. Unité de puissance auxiliaire (UPA) comprenant : quels peuvent être déplacées entre des positions 30 ouvrant et fermant substantiellement l’entrée, le dis- un compresseur de charge (14) muni d’un rotor positif de commande de l’UPA (32) réagissant en (28) ; outre, si la vitesse de rotation de consigne est attein- un moteur d’UPA prévu pour être mis en prise te, de manière à : mécaniquementau compresseur de charge (14) pour entraîner le compresseur de charge (14) 35 moduler la pluralité d’ailettes de guidage d’en- pour fournir de la puissance pneumatique et trée (45) substantiellement en position ouverte ; pour être désengagé de celui-ci lorsqu’il n’y a et plus besoin de puissance pneumatique ; ouvrir une vanne de purge du compresseur de un organe d’accouplement (29) accouplé entre charge. le compresseur de charge et le moteur d’UPA 40 et configuré pour être déplacé de manière com- 4. Unité de puissance auxiliaire selon la revendication mandable entre une position engagée, dans la- 1, dans laquelle le moteur d’UPA comprend un com- quelle le moteur d’UPA est en prise mécanique- presseur de générateur de gaz, un brûleur, et une ment avec le compresseur de charge (14), et turbine de générateur de gaz, et dans laquelle le une position désengagée, dans laquelle le mo- 45 moyen de pré-rotation comprend un circuit d’air de teur d’UPA est désengagé du compresseur de purge (37) prévu pour fournir de l’air de purge de charge (14) ; décharge du compresseur de manière à effectuer la caractérisée en ce qu’ elle comprend en outre : pré-rotation du rotor (28) à la vitesse de rotation de consigne, le compresseur de générateur de gaz un moyen de pré-rotation accouplé au com- 50 étant prévu pour fournir de l’air de purge de décharge presseur de charge (14) et configuré pour du compresseur dans le circuit d’air de purge (37) effectuer la pré-rotation sélective du rotor pour provoquer la pré-rotation du rotor (28) à la vi- (28) ; et tesse de rotation de consigne, la vitesse de rotation un dispositif de commande d’UPA (32) ac- de consigne comprenant la vitesse de rotation à la- couplé fonctionnellement au compresseur 55 quelle la vitesse de rotation du rotor (28) correspond de charge (14), au moteur d’UPA, à l’organe à un pourcentage prédéterminé de la vitesse de ro- d’accouplement (29) et au moyen de pré- tation d’un arbre de sortie du moteur d’UPA ou d’un rotation, le dispositif de commande d’UPA arbre de sortie de boîte de vitesses.

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5. Unité de puissance auxiliaire selon la revendication du compresseur de charge avec le moteur d’UPA en 4, dans laquelle l’organe d’accouplement (29) com- fonctionnement comprend l’activation d’un action- prend un organe d’accouplement sans embrayage neur pour déplacer l’organe d’accouplement (29) (29) ou un embrayage à friction, et si l’organe d’ac- dans une position engagée. couplement (29) comprend un organe d’accouple- 5 ment sans embrayage (29), le pourcentage prédé- 10. Procédé selon la revendication 9, dans lequel l’étape terminé est de 100 %. (200) d’entraînement en pré-rotation du rotor (28) à la vitesse de rotation de consigne comprend l’entraî- 6. Procédé (100) pour activer et désactiver un com- nement en pré-rotation du rotor (28) à une vitesse presseur de charge (14) dans une unité de puissan- 10 de rotation qui représente 100 % de la vitesse de ce auxiliaire (UPA) en fonctionnement comprenant rotation du moteur d’UPA lorsque l’organe d’accou- un moteur d’UPA et un compresseur de charge, le plement (29) comprend l’organe d’accouplement procédé comprenant : sans embrayage (29).

l’engagement sélectif du compresseur de char- 15 11. Procédé selon la revendication 7, dans lequel l’étape ge avec le moteur d’UPA pour activer le com- (300) de désengagement sélectif du compresseur presseur de charge, caractérisé par : de charge du moteur d’UPA en fonctionnement comprend : l’entraînement en pré-rotation d’un rotor (28) du compresseur de charge jusqu’à une 20 moduler une pluralité d’ailettes de guidage d’en- vitesse de rotation de consigne avec l’air de trée (45) substantiellement en position fermée purge de décharge du compresseur (200) ; pour interrompre l’écoulement d’air de purge de et décharge du compresseur dans le rotor (28) ; et l’engagement mécanique du compresseur fournir une réduction de puissance temporaire de charge (14) avec le moteur d’UPA lors- 25 du générateur de gaz. qu’une vitesse de rotation du rotor (28) at- teint la vitesse de rotation de consigne 12. Procédé selon la revendication 9, dans lequel l’étape (250) ; et (200 et 250) d’engagement mécanique du compres- le désengagement sélectif du compresseur seur de charge avec le moteur d’UPA lorsqu’une vi- de charge (14) du moteur d’UPA en fonc- 30 tesse de rotation du rotor (28) atteint la vitesse de tionnement pour désactiver le compresseur rotation de consigne comprend : de charge (300). la détermination d’une valeur de signal de vites- 7. Procédé selon la revendication 6, dans lequel le mo- se du rotor (28) ; teur d’UPA comprend un compresseur de généra- 35 la détermination d’une valeur de signal de vites- teur degaz, l’étape (200 et250) consistant àengager se du moteur d’UPA ; de manière sélective le compresseur de charge avec la comparaison de la valeur de signal de vitesse le moteur d’UPA comprend en outre l’ouverture du rotor (28) avec la valeur de signal de vitesse d’une vanne d’air de purge (39) disposée entre le du moteur d’UPA ; et compresseur de générateur de gaz et le compres- 40 l’activation de l’actionneur pour déplacer l’orga- seur de charge et d’un collecteur d’entrée de pré- ne d’accouplement sans embrayage (29) dans rotation de telle sorte que l’air de purge de décharge la position engagée lorsque la valeur de signal du compresseur s’écoule dans le rotor (28). de vitesse du rotor (28) correspond à la valeur de signal de vitesse du moteur d’UPA de telle 8. Procédé selon la revendication 6, dans lequel l’étape 45 sorte que le moteur d’UPA en fonctionnement (200) d’entraînement en pré-rotation du rotor (28) soit en prise avec, et entraîne, le compresseur jusqu’à la vitesse de rotation de consigne comprend de charge pour fournir une puissance pneuma- la mise en contact d’une surface circonférentielle du tique. rotor (28) du compresseur de charge avec de l’air de purge de décharge du compresseur à haute pres- 50 13. Système pour activer et désactiver un compresseur sion. de charge (14) dans une unité de puissance auxi- liaire (UPA) en fonctionnement, comportant un mo- 9. Procédé selon la revendication 6, dans lequel un or- teur d’UPA, le système comprenant : gane d’accouplement (29) est accouplé entre le compresseur de charge et le moteur d’UPA, l’organe 55 le compresseur de charge en communication d’accouplement (29) comprenant un organe d’ac- d’écoulement fluidique avec une source d’air de couplement sans embrayage (29) ou un embrayage purge de décharge du compresseur et prévu à friction, et l’étape (250) d’engagement mécanique pour être engagé mécaniquement avec le mo-

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teur d’UPA lorsqu’il existe une demande de pour activer l’actionneur de l’organe d’accouplement compresseur de charge (14) et pour être désen- (29) sur la base d’une comparaison entre le premier gagé de celui-ci lorsqu’il n’y a pas de demande ; et le deuxième signal de vitesse, l’actionneur de l’or- un organe d’accouplement (29) accouplé entre gane d’accouplement (29) étant activé si la vitesse le compresseur de charge et le moteur d’UPA et 5 de rotation de consigne est atteinte. configuré pour être déplacé de manière com- mandable entre une position engagée dans la- quelle le compresseur de charge est en prise mécanique avec le moteur d’UPA, et une posi- tion désengagée dans laquelle le moteur d’UPA 10 est désengagé du compresseur de charge (14) ; caractérisé en ce qu’il comprend en outre :

un circuit de commande de purge pour four- nir l’air de purge de décharge du compres- 15 seur à un rotor (28) du compresseur de charge de manière à effectuer la pré-rota- tion du rotor (28) à une vitesse de rotation de consigne ; un dispositif de commande d’UPA (32) ac- 20 couplé fonctionnellement au compresseur de charge (14), au circuit de commande de purge, à un actionneur de l’organe d’accou- plement (29) et au moteur d’UPA et prévu pour recevoir un premier signal de vitesse 25 représentatifd’une vitesse de rotation du ro- tor (28) du compresseur de charge et un deuxième signal de vitesse représentatif d’une vitesse de rotation du moteur d’UPA et configuré, en réponse à ceux-ci, pour (i) 30 amener de manière sélective l’air de purge de décharge du compresseur à provoquer la pré-rotation du rotor (28) ; et (ii) déplacer l’organe d’accouplement (29) entre les po- sitions engagée et désengagée, l’action- 35 neur de l’organe d’accouplement (29) dé- plaçant l’organe d’accouplement (29) dans la position engagée lorsque la vitesse de rotation du rotor (28) correspond à la vitesse de rotation de consigne. 40

14. Système selon la revendication 13, dans lequel le circuit d’air de purge (37) présente une entrée et une sortie de circuit d’air de purge (37), l’entrée de circuit d’air de purge (37) étant prévue pour recevoir l’air 45 de purge de décharge du compresseur et la sortie étant prévue pour fournir l’air de purge de décharge du compresseur de manière à provoquer la pré-ro- tation du rotor (28), le circuit d’air de purge (37) com- portant une vanne de commande de purge disposée 50 fonctionnellement dans le circuit d’air de purge (37) en amont du compresseur de charge de manière à moduler ou à couper et mettre en route l’écoulement d’air de purge de décharge du compresseur vers le compresseur de charge (14). 55

15. Système selon la revendication 13, dans lequel le dispositif de commande d’UPA (32) est configuré

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REFERENCES CITED IN THE DESCRIPTION

This list of references cited by the applicant is for the reader’s convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description

• EP 2347956 A [0004]

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