초록 ▼

A starting system and method for a gas turbine engine applies a change in conventional starter generator torque profiles near the conclusion of the start cycle after the engine self sustaining speed and just prior to starter generator cut-out. By decreasing the applied torque to zero prior to transi

A starting system and method for a gas turbine engine applies a change in conventional starter generator torque profiles near the conclusion of the start cycle after the engine self sustaining speed and just prior to starter generator cut-out. By decreasing the applied torque to zero prior to transition from a start mode to a generator mode, both the mechanical and electrical transients are greatly decreased.

대표청구항 ▼

What is claimed is: 1. A method of operating a starter generator system comprising the steps of: (1) operating a starter motor to generate an output torque; (2) spooling up an engine with the output torque from the starter motor; (3) reducing the output torque from a constant power region in which

What is claimed is: 1. A method of operating a starter generator system comprising the steps of: (1) operating a starter motor to generate an output torque; (2) spooling up an engine with the output torque from the starter motor; (3) reducing the output torque from a constant power region in which the output torque is decreased in response to an increase in engine speed so as to maintain a generally constant power output, then reducing the output torque according to a ramp function having a slope steeper than that within the constant power region to approximately zero in response to transitioning the starter motor from a start mode in which the starter motor drives the engine to a generator mode in which the starter motor is driven by the engine. 2. A method as recited in claim 1, wherein the engine achieves a self-sustaining speed during said step (3). 3. A method as recited in claim 2, wherein the self-sustaining speed is an engine speed in which the engine achieves an approximately zero drag torque. 4. A method as recited in claim 1, further comprising the step of: (4) operating the starter motor as a generator after the engine lights off. 5. A method as recited in claim 1, wherein said step (3) includes: (a) reducing the output torque from a speed which relates to a predetermined engine operating speed to zero commensurate with transition from the start mode to the generator mode, the reduction represented as a ramp function in a starter generator torque profile curve. 6. A method of starting a gas turbine engine comprising the steps of: (1) operating a starter motor within a constant torque region to generate an output torque; (2) spooling up an engine with the output torque from the starter motor in response to said step (1); (3) operating the starter motor within a constant power region in which the output torque is decreased in response to an increase in engine speed so as to maintain a generally constant power output; (4) lighting off the gas turbine engine during said step (3); (5) reducing the output torque after said step (4) according to a ramp function having a slope steeper than that during said step (3) to approximately zero in response to transitioning the starter motor from a start mode in which the starter motor drives the engine to a generator mode in which the starter motor is driven by the engine. 7. A method as recited in claim 6, wherein said step (5) includes: (a) reducing the output torque from a speed which relates to a predetermined engine operating speed to zero commensurate with transition from the start mode to the generator mode, the reduction represented as a ramp function in a starter generator torque profile curve. 8. A method as recited in claim 6, wherein said step (5) includes: (a) reducing the output torque according to the algorithm until a speed n2 where T=Torque; K=Constant; n=speed; n1=speed at which the linear ramp function begins at the transition between the start mode and the generator mode; n2=speed at which the linear ramp function reaches zero torque. 9. A method of starting a gas turbine engine comprising the steps of: (1) operating a starter motor within a constant torque region to generate an output torque; (2) spooling up an engine with the output torque from the starter motor in response to said step (1); (3) operating the starter motor within a constant power region in which the output torque is decreased in response to an increase in engine speed so as to maintain a generally constant power output; (4) lighting off the gas turbine engine; (5) reducing the output torque to approximately zero in response to the gas turbine engine reaching a self-sustaining speed in which the engine achieves an approximately zero drag torque including reducing the output torque according to the algorithm until a speed n2 where T=Torque; K=Constant; n=speed; n1=speed at which the linear ramp function begins at the transition between the start mode and the generator mode; n2=speed at which the linear ramp function reaches zero torque. 10. A method as recited in claim 9, further comprising the step of: (6) operating the starter motor as a generator after the engine achieves the predetermined speed. 11. A method as recited in claim 9, wherein said step (5) includes: (a) reducing the output torque from a speed which relates to a predetermined engine operating speed to zero in response to transitioning the starter motor from a start mode in which the starter motor drives the engine to a generator mode in which the starter motor is driven by the engine. 12. A method of operating a starter generator system comprising the steps of: (1) operating a starter motor to generate an output torque; (2) spooling up an engine with the output torque from the starter motor; (3) reducing the output torque to approximately zero in response to transitioning the starter motor from a start mode in which the starter motor drives the engine to a generator mode in which the starter motor is driven by the engine including reducing the output torque according to a linear ramp function algorithm until a speed n1 where T=Torque; K=Constant; and n=speed, where n1=speed at which the linear ramp function begins at the transition between the start mode and the generator mode; and reducing the output torque according to the algorithm until a speed n2 where n2=speed at which the linear ramp function reaches zero torque. 13. A method of starting a gas turbine engine comprising the steps of: (1) operating a starter motor within a constant torque region to generate an output torque; (2) spooling up an engine with the output torque from the starter motor in response to said step (1); (3) operating the starter motor within a constant power region in which the output torque is decreased in response to an increase in engine speed so as to maintain a generally constant power output; (4) lighting off the gas turbine engine; (5) reducing the output torque to approximately zero in response to transitioning the starter motor from a start mode in which the starter motor drives the engine to a generator mode in which the starter motor is driven by the engine including reducing the output torque according to a linear ramp function algorithm until a speed n1 where T=Torque; K=Constant; and n=speed, where n1=speed at which the linear ramp function begins at the transition between the start mode and the generator mode. 14. A method of starting a gas turbine engine comprising the steps of: (1) operating a starter motor within a constant torque region to generate an output torque; (2) spooling up an engine with the output torque from the starter motor in response to said step (1); (3) operating the starter motor within a constant power region in which the output torque is decreased in response to an increase in engine speed so as to maintain a generally constant power output; (4) lighting off the gas turbine engine; (5) reducing the output torque to approximately zero in response to transitioning the starter motor from a start mode in which the starter motor drives the engine to a generator mode in which the starter motor is driven by the engine including reducing the output torque according to the algorithm until a speed n2 where T=Torque; K=Constant; n=speed; n1=speed at which the linear ramp function begins at the transition between the start mode and the generator mode; n2=speed at which the linear ramp function reaches zero torque.