Method for accelerating a gas turbine engine

• US 5,127,220 A
• Filed: 02/28/1991
• Issued: 07/07/1992
• Est. Priority Date: 02/28/1991
• Status: Expired due to Fees

• Current Assignee: Alliedsignal Inc.
• Original Assignee: Alliedsignal Inc.
• Inventors: Carlson, Todd S., Jesrai, Tariq
• Primary Examiner(s): Casaregola, Louis J.
• Application Number:
  US07/662,527
• Time in Patent Office: 495 Days
• Field of Search: 60/39.02, 60/39.091, 60/39.141, 60/39.142, 74/7 R, 74/7 C
• US Class Current: 60/778
• CPC Class Codes: F02C 7/26 Starting; Ignition
• CPC Class Codes: F02C 7/277 the starter being a separate turbine

Abstract

A method for accelerating a gas turbine engine (10) with an air turbine starter (14) employs sensor data (48, 50) indicative of both starter speed and engine speed to enable speed-synchronized engagement of the starter output shaft (16) with an engine input shaft (18), thereby minimizing clutch damage and engine restart time.

Claims

1. A method for accelerating a gas turbine engine with an air turbine starter, wherein the starter has an output shaft that is selectively engageable in driving relation with an input shaft which is engaged with the engine, and wherein the starter is adapted to receive and be driven by pressurized air delivered to an inlet of the starter via a flow control valve, comprising the steps of:

(a) sensing the rotational speed, "F₁ ", of the output shaft;

(b) sensing the rotational speed, "F₂ ", of the input shaft; and

(c) selectively responding to the sensed rotational speeds when F₂ is initially greater than F₁ but less than a predetermined speed by;

(1) first, increasing mass flow of the air to the starter inlet whereby the starter is accelerated until F₁ exceeds F₂ ;

(2) second, decreasing mass flow of the air to the starter inlet whereby the starter is decelerated until F₁ is substantially equal to F₂ ;

(3) third, engaging the output shaft in driving relation with the input shaft when F₁ is substantially equal to F₂ ; and

(4) fourth, again increasing mass flow of the air to the starter inlet whereby the engine is accelerated until F₂ is substantially equal to the predetermined speed.

2. A method as recited in Claim 1 comprising the further step of:

(5) fifth, disengaging the output shaft from driving relation with the input shaft when F₂ is substantially equal to the predetermined speed.

3. A method for accelerating a gas turbine engine with an air, turbine starter, wherein the starter has an output shaft that is selectively engageable in driving relation with an input shaft which is engaged with the engine, and wherein the starter is adapted to receive and be driven by pressurized air delivered to an inlet of the starter via a flow control valve, comprising the steps of:

(a) sensing the rotational speed of the output shaft;

(b) sensing the rotational speed of the input shaft; and

(c) selectively responding to the sensed rotational speeds when the speed of the input shaft is greater than the speed of the output shaft but less than a predetermined speed by;

(1) increasing mass flow of the air to the inlet whereby the starter is accelerated to a speed at which the speed of the output shaft is substantially the same as the speed of the input shaft; and

(2) engaging the output shaft in driving relation with the input shaft when the speeds of the shafts are substantially the same.

4. A method as recited in claim 3 wherein the increasing and engaging steps are implemented in the order recited.

5. A method as recited in claim 4 wherein the mass flow is increased until the speed of the output shaft exceeds the speed of the input shaft, and further comprising the step of:

(3) decreasing the mass flow when the speed of the output shaft exceeds the speed of the output shaft exceeds the speed of the input shaft whereby the starter is decelerated to a speed at which the speeds of the input and output shafts are substantially the same.

6. A method as recited in claim 5 comprising the further step, implemented after the recited increasing, decreasing, and engaging steps are implemented, of again increasing the mass flow whereby the starter is accelerated until the speed of the input shaft is substantially the same as the predetermined speed.