Turboshaft engine comprising a controlled mechanical coupling device, helicopter equipped with such a turboshaft engine, and method for optimising the zero-power super-idle speed of such a helicopter

Patent metadata

Field	Value
Publication number	US-10415482-B2
Application number	US-201515128375-A
Country	US
Kind code	B2
Filing date	Mar 20, 2015
Priority date	Mar 27, 2014
Publication date	Sep 17, 2019
Grant date	Sep 17, 2019

Abstract

The invention relates to a turboshaft engine comprising a gas generator ( 5 ) that is capable of being rotated, and a free turbine ( 6 ) that is rotated by the gases of said gas generator, characterized in that it comprises a device ( 40 ) for controlled mechanical coupling of said gas generator ( 5 ) and said free turbine ( 6 ) that is capable of connecting said gas generator ( 5 ) and said free turbine ( 6 ) mechanically and on demand as soon as the rotational speed of said gas generator ( 5 ) reaches a predetermined threshold speed.

First claim

The invention claimed is:

1. A turboshaft engine comprising
a gas generator that is capable of being rotated,
a free turbine that is rotated by gases of said gas generator, and
a device for controlled mechanical coupling of said gas generator and said free turbine, which device is capable of connecting said gas generator and said free turbine mechanically and on demand as soon as a rotational speed of said gas generator reaches a predetermined threshold speed, wherein said device for controlled mechanical coupling of said gas generator and said free turbine is capable of connecting said gas generator and said free turbine mechanically and on demand as soon as said rotational speed of said gas generator is less than said predetermined threshold speed, and of separating said gas generator and said free turbine on demand as soon as said rotational speed of said gas generator is greater than said predetermined threshold speed, and wherein the turboshaft engine further comprises a device for spontaneously mechanically coupling said gas generator and said free turbine, which device is capable of mechanically and spontaneously connecting said gas generator and said free turbine as soon as a ratio of the rotational speed of said gas generator to the rotational speed of said free turbine reaches a predetermined threshold value.

2. The turboshaft engine according to claim 1 , wherein said predetermined threshold speed depends on a nominal speed of said gas generator.

3. The turboshaft engine according to claim 2 , wherein said predetermined threshold speed is selected within a range of [20%.N1, 60%.N1], where N1 is said nominal speed of said gas generator.

4. The turboshaft engine according to claim 1 , wherein said device for controlled mechanical coupling of said gas generator and said free turbine comprises:
means for reading information that is representative of said rotational speed of said gas generator,
means for reversible mechanical coupling between a shaft that is mechanically connected to said gas generator and a shaft that is mechanically connected to said free turbine,
wherein said means for reversible mechanical coupling is controlled on the basis of said information that is representative of said rotational speed of said gas generator, and on the basis of said predetermined threshold speed.

5. The turboshaft engine according to claim 4 , wherein said means for reversible mechanical coupling are selected from a group comprising at least one friction clutch, a pawl, and a pawl provided with a synchronizer.

6. The turboshaft engine according to claim 4 , wherein said means for reversible mechanical coupling are designed to allow temporary sliding, during a preliminary coupling phase, between the shaft that is mechanically connected to said gas generator and the shaft hat is mechanically connected to said free turbine.

7. The turboshaft engine according to claim 1 , wherein said device for spontaneously mechanically coupling said gas generator and said free turbine is capable of mechanically and spontaneously connecting said gas generator and said free turbine as soon as the ratio of the speeds is less than said predetermined threshold value, and of spontaneously separating said gas generator and said free turbine as soon as said ratio is greater than said predetermined threshold value.

8. The turboshaft engine according to claim 1 , wherein said device for spontaneously mechanically coupling said gas generator and said free turbine comprises at least one free wheel which connects a first shaft which, together with said gas generator, has a reduction ratio K1, and a second shaft which, together with the free turbine, has a reduction ratio K2, said free wheel being arranged such that said free turbine spontaneously drives said gas generator, by means of said first and second shafts and said free wheel, as soon as said ratio of the speeds is less than a ratio K2/K1.

9. The turboshaft engine according to claim 8 , wherein it comprises a starter-generator that is rigidly connected to an intermediate shaft, and in that said spontaneous mechanical coupling device comprises two free wheels which connect said intermediate shaft to said first shaft, which, together with said gas generator, has the reduction ratio K1, and to said second shaft, respectively, which second shaft, together with the free turbine, has the reduction ratio K2, said wheels being arranged such that said free turbine spontaneously drives said gas generator by means of said shafts and said two free wheels when said ratio of the speeds is less than the ratio K2/K1.

10. A twin-engine helicopter, wherein the twin engine helicopter comprises at least one turboshaft engine according to claim 1 .

11. A method for optimising a zero-power super-idling mode of a twin-engine helicopter comprising at least one turboshaft engine comprising a gas generator that is capable of being rotated and a free turbine that is rotated by gases of said gas generator, wherein the method comprises a step of controlled mechanical coupling of said gas generator and said free turbine as soon as a rotational speed of said gas generator reaches a predetermined threshold speed, and a step of spontaneously mechanically coupling said gas generator and the free turbine as soon as a ratio of the rotational speed of said gas generator to the rotational speed of said free turbine reaches a predetermined threshold value.

Assignees

• Safran Helicopter Engines

Inventors

• Marconi Patrick
• Thiriet Romain
• Serghine Camel

Classifications

• F02C3/113 Primary

  with variable power transmission between rotors · CPC title

• F02C3/10 Primary

  with another turbine driving an output shaft but not driving the compressor · CPC title

• F05D2220/329

  in helicopters · CPC title

• F02C3/04

  having a turbine driving a compressor (power transmission arrangements F02C7/36; control of working fluid flow F02C9/16) · CPC title

• F05D2260/40

  Transmission of power · CPC title