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Emergency device for relighting a windmilling turbojet

Imported: 24 Feb '17 | Published: 06 Jan '04

Michel Franchet, Guy Hebraud

USPTO - Utility Patents

Abstract

An emergency device for relighting a windmilling turbojet, the jet comprising a fan driven by a low-pressure turbine via a first shaft and a compressor driven by a high-pressure turbine via a second shaft disposed coaxially around the first shaft, a differential interconnecting said first and second shafts while compensating for their different speeds of rotation in normal operation or the turbojet, and a braking system connected to the differential so as to enable it to be slowed down or blocked when the turbojet shuts down, thereby enabling the first shaft to entrain the second shaft so that it reaches a speed that favors relighting of the turbojet.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the present invention appear from the description given below, with reference to the accompanying drawings which show an embodiment that has no limiting character. In the figures:

FIG. 1 is a fragmentary diagrammatic view of a turbojet including a first embodiment of a relighting device of the invention;

FIG. 2 is a diagrammatic view of the FIG. 1 differential in a co-rotating shaft configuration;

FIG. 3 is a section view on III—III of FIG. 2;

FIG. 4 is a diagrammatic view of the FIG. 1 differential in a contra-rotating shaft configuration; and

FIG. 5 is a fragmentary diagrammatic view of a turbojet including a second embodiment of a lighting device of the invention.

Claims

1. An emergency device for relighting a windmilling turbojet, the jet comprising a fan driven by a low-pressure turbine via a first shaft and a compressor driven by a high-pressure turbine via a second shaft disposed coaxially around the first shaft, said device comprising a differential interconnecting said first and second shafts while compensating for their different speeds of rotation in normal operation of the turbojet, and a braking system connected to the differential so as to enable it to be slowed down or blocked when the turbojet shuts down, thereby enabling the first shaft to drive the second shaft so that it reaches a speed that favors relighting of the turbojet.

2. A device according to claim 1, wherein the differential comprises at least one planet-carrying annular gear rotating about the first and second shafts and coupled in rotation with a rotary portion of the braking system.

3. A device according to claim 1, wherein the differential acts as a multiplier from the first shaft to the second shaft when it is slowed down or blocked by the braking system.

4. A device according to claim 1, wherein the first and second shafts are co-rotating shafts.

5. A device according to claim 1, wherein the first and second shafts are contra-rotating shafts.

6. A device according to claim 1, wherein the braking system includes at least one disk brake.

7. A device according to claim 1, wherein the braking system includes a retarder.

8. A device according to claim 1, wherein the differential is placed together with the braking system outside an intermediate casing.

9. A device according to claim 1, further comprising an electronic computer enabling the braking system to be controlled and calculating the braking pressure that is required to adapt the transfer of energy from the first shaft to the second shaft.