Modified start sequence of a gas turbine engine

Patent metadata

Field	Value
Publication number	US-10040577-B2
Application number	US-201615042363-A
Country	US
Kind code	B2
Filing date	Feb 12, 2016
Priority date	Feb 12, 2016
Publication date	Aug 7, 2018
Grant date	Aug 7, 2018

Abstract

A system for starting a gas turbine engine of an aircraft is provided. The system includes a pneumatic starter motor, a discrete starter valve switchable between an on-state and an off-state, and a controller operable to perform a starting sequence for the gas turbine engine. The starting sequence includes alternating on and off commands to an electromechanical device coupled to the discrete starter valve to achieve a partially open position of the discrete starter valve to control a flow from a starter air supply to the pneumatic starter motor to drive rotation of a starting spool of the gas turbine engine below an engine idle speed.

First claim

The invention claimed is:

1. A system for starting a gas turbine engine of an aircraft, the system comprising:
a pneumatic starter motor;
a discrete starter valve switchable between an on-state and an off-state;
a controller operable to perform a starting sequence for the gas turbine engine, the starting sequence comprising alternating on and off commands to an electromechanical device coupled to the discrete starter valve to achieve a partially open position of the discrete starter valve to control a flow from a starter air supply to the pneumatic starter motor to drive rotation of a starting spool of the gas turbine engine below an engine idle speed;
an electronic engine control system comprising:
a memory for recording a current heat state of the gas turbine engine at shutdown and for recording a shutdown time of the gas turbine engine; and
a risk model for determining a time period (t motoring ) for motoring the gas turbine engine at a predetermined speed N target wherein the predetermined speed is less than a speed used to start the gas turbine engine and wherein t motoring is a function of the heat state recorded at engine shutdown and an elapsed time of an engine start request relative to the previous shutdown time.

2. The system as in claim 1 , wherein the electromechanical device has a cycle time defined between an off-command to an on-command to the off-command that is at most half of a movement time for the discrete starter valve to transition from fully closed to fully open.

3. The system as in claim 1 , wherein the electromechanical device is a solenoid that positions the discrete starter valve based on intermittently supplied electric power.

4. The system as in claim 1 , wherein the electromechanical device is an electric valve controlling muscle air to adjust the position of the discrete starter valve.

5. The system as in claim 1 , wherein the controller modulates the on and off commands to the electromechanical device to further open the discrete starter valve and increase a rotational speed of the starting spool.

6. The system as in claim 1 , wherein the time period (t motoring ) is calculated automatically during a start of the gas turbine engine.

7. The system as in claim 1 , wherein the controller modulates a duty cycle of the discrete starter valve via pulse width modulation.

8. The system as in claim 1 , wherein the predetermined speed N target is within a predetermined speed range N targetMin to N targetMax that is used regardless of the calculated time period t motoring .

Assignees

• United Technologies Corp

Inventors

• Teicholz Matthew D
• Sutliff Jeffrey W
• Greene Jr William H
• White Kenneth J
• Feulner Matthew R
• Virtue Jr John P
• Glahn Jorn A
• Hoover Philip D
• Pinedo Victor M
• Solomonides Jason B

Classifications

• F05D2270/71

  synthesized, i.e. parameter computed by a mathematical model · CPC title

• B64D27/16

  of jet type · CPC title

• F02C7/27

  Fluid drives (turbine starters F02C7/277) · CPC title

• F05D2260/85

  Starting · CPC title

• F05D2270/303

  Temperature · CPC title