Systems and methods for controlling aircraft main engine speeds by adjusting compressed air flow from an APU

Patent metadata

Field	Value
Publication number	US-9567906-B2
Application number	US-201314105844-A
Country	US
Kind code	B2
Filing date	Dec 13, 2013
Priority date	Dec 13, 2013
Publication date	Feb 14, 2017
Grant date	Feb 14, 2017

Abstract

An aircraft engine system includes a main engine having a main engine speed; a starter coupled to the main engine and configured to drive the main engine with compressed air; and an auxiliary power unit (APU) system coupled to the starter and configured to provide the compressed air to the starter. The APU system includes an APU with a compressor to generate the compressed air, and an APU electronic control unit (ECU) coupled to the APU, the APU ECU configured to receive the engine speed of the main engine and to control operation of the APU to modify an amount of the compressed air to the starter based on the main engine speed.

First claim

What is claimed is:

1. An aircraft engine system, comprising:
a main engine having a main engine speed;
a starter coupled to the main engine and configured to drive the main engine; and
an auxiliary power unit (APU) system coupled to the starter and configured to provide the compressed air to the starter, the APU system comprising
an APU with a compressor to generate the compressed air,
an APU electronic control unit (ECU) coupled to the APU, the APU ECU configured to receive the engine speed of the main engine and to control operation of the APU to modify an amount of the compressed air to the starter based on the main engine speed.

wherein the compressor of the APU includes inlet guide vanes, and wherein the APU ECU is configured to adjust a position of the inlet guide vanes based on the main engine speed,
wherein the APU further includes a surge control valve, and wherein the APU ECU is configured to adjust a position of the surge control valve based on the main engine speed,
wherein the APU ECU controls operation of the APU based on a main engine cold motoring command to produce the amount of the compressed air to the starter such that a predetermined engine speed is achieved, and
wherein, upon withdrawal of the main engine cold motoring command and receipt of an ignition command, the APU ECU is configured to adjust the position of the inlet guide vanes to a maximum position and the position of the surge control valve to a minimum position.

2. The aircraft engine system of claim 1 , further comprising a full authority digital engine controller (FADEC) coupled to the main engine and the APU ECU, wherein the FADEC is configured to determine the main engine speed and provide the main engine speed to the APU ECU.

3. The aircraft engine system of claim 2 , wherein the FADEC is configured to generate the main engine cold motoring command and to provide the main engine cold motoring command to the APU ECU.

4. The engine system of claim 3 , wherein the APU ECU is configured to control operation of the APU to maintain the predetermined engine speed until the main engine cold motoring command is withdrawn.

5. The engine system of claim 4 , wherein the FADEC is configured to generate the ignition command and to provide the ignition command to the APU ECU.

6. A method of operating an aircraft engine system, comprising the following steps:
receiving, at an auxiliary power unit (APU) electronic control unit (ECU), a main engine cold motoring command;
receiving, at the APU ECU, a main engine speed of a main engine;
controlling operation of an auxiliary power unit (APU) based on the main engine speed and the engine cold motoring command until a predetermined main engine speed of the main engine is achieved;
wherein the controlling including adjusting inlet guide vanes of the APU based on the main engine speed and the engine cold motoring command and adjusting a surge control valve of the APU based on the main engine speed and the engine cold motoring command;
providing, prior to achieving the predetermined main engine speed of the main engine, compressed air from a compressor of the APU to a starter that drives the main engine;
receiving, at the APU ECU, an ignition command, and
controlling, upon receipt of the ignition command, operation of the APU by adjusting the inlet guide vanes to a maximum position and the surge control valve to a minimum position until the ignition command is withdrawn.

7. The method of claim 6 , wherein the receiving step includes receiving the main engine speed from a full authority digital engine controller (FADEC).

8. The method of claim 7 , wherein the controlling step includes controlling operation of the APU at the predetermined main engine speed until the main engine cold motoring command is withdrawn.

9. The method of claim 7 , further comprising the step of
idling, upon withdrawal of the ignition command, operation of the APU.

10. An auxiliary power unit (APU) system to assist a main engine during a start operation, the APU system comprising:
an APU compressor with inlet guide vanes, the APU compressor configured to receive ambient air through the inlet guide vanes and to compress the ambient air to generate compressed air; and
an APU electronic control unit (ECU) coupled to the inlet guide vanes and configured to adjust a position of the inlet guide vanes based on a main engine speed of the main engine; and
a surge control valve configured to remove bleed air from the compressed air, wherein the APU ECU is further configured to adjust a position of the surge control valve based on the main engine speed of the main engine,
wherein the APU ECU is further configured to adjust the position of the inlet guide vanes and the position of the surge control valve based on a main engine cold motoring command during the start operation, and
wherein the APU ECU is further configured to continue adjusting the position of the inlet guide vanes and the position of the surge control valve to achieve a predetermined main engine speed during the start operation.

11. The APU system of claim 10 , wherein the APU ECU is further configured to adjust the position of the inlet guide vanes and the position of the surge control valve based on an ignition command during the start operation.

Assignees

• Honeywell Int Inc

Inventors

• Nesdill Thomas
• Dwyer Michael
• Arenare John
• Lam Cecilia

Classifications

• F05D2260/85

  Starting · CPC title

• F02C7/057 Primary

  Control or regulation (conjointly with fuel supply control F02C9/50, with nozzle area control F02K1/16) · CPC title

• F05D2270/306

  Mass flow · CPC title

• F02C7/26

  Starting; Ignition · CPC title

• F02C9/20

  by throttling; by adjusting vanes · CPC title