Automatic Shut-Off Valve For The Oil Circuit In An Airplane Engine

Abstract

The present invention concerns a lubrication system in a closed circuit provided with a valve comprising a first position and a second position, as well as an IN inlet, a first BP outlet and a second M outlet, said IN inlet being connected to the outlet of the feed pump, the first BP outlet being connected to the bypass circuit and the second M outlet being connected to the feed circuit. In the first position of the valve, the flow entering via the IN inlet is diverted to the first BP outlet and in the second position, the incoming flow is diverted to the second M outlet, said valve switching from the first position to the second position and vice versa, when the incoming flow rate exceeds a predetermined threshold upwards and downwards respectively.

Description

SUBJECT OF THE INVENTION[0001]The present invention concerns an automatic shut-off and isolation valve for the oil circuit in an aircraft engine, in particular in a turbojet or a turboprop.STATE OF THE ART[0002]With certain turbojets, when the aircraft is stopping, it is interesting to stop or reduce the oil supply to the bearing housings before the aircraft has completely stopped, so as to permit a complete drainage of these housings, whilst the rotation is ceasing. In fact, in these aircraft, the oil is supplied to the housings by a pump, the feed pump, and collected at the bottom of these housings by another pump, the collection pump. Both pumps being of a volumetric type and driven by the main shaft of the engine or HP shaft, they continue to work until this shaft comes to a complete stop.[0003]In certain cases, an imbalance may occur between the oil supplied by the feed pump and the collection pump or pumps, which may cause an excess of oil to appear in the housing and cause le...

AI Technical Summary

Problems solved by technology

In certain cases, an imbalance may occur between the oil supplied by the feed pump and the collection pump or pumps, which may cause an excess of oil to appear in the housing and cause leaks

This imbalance may also lead to the stagnation of oil in the housings during stopping phases of the engine and may cause the coking of the stagnant oil, especially in engines with one or several housings which are particularly hot or particularly sensitive to the phenomenon known as “soak back”, of the temporary heating of the mechanical parts when the engine is stopped.

Moreover the control of such devices to get a cut-off at a significant speed during stopping, so as to ensure a good drainage, might lead to make the re-ignition of the pump impossible on restart.

Certain “anti-siphon” devices do not show this disadvantage, but then they are based on a more or less complex control system, which often consumes oil, and which is useless in many engines.

None of these systems allows to efficiently prevent the stagnation of oil in the housings during the stopping phases of the engine.

In particular, none of these systems describes a device that would prevent the phenomenon of coking of the stagnant oil.

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