Electric motor driven auxiliary oil system for geared gas turbine engine

A gas turbine engine includes a fan drive turbine, a fan rotor, and a gear reduction driven by the fan drive turbine and, in turn, to drive the fan rotor. A main oil supply system supplies oil to components within the gear reduction, and an auxiliary oil supply system. The auxiliary oil supply system includes a rotation sensor for sensing rotation of a component that will rotate with the fan rotor, a control, an auxiliary oil pump, and a main supply sensor for sensing operation of the main oil supply system. The control is programmed to supply oil from the auxiliary oil pump to the gear reduction when the rotation sensor senses the component is rotating. A determination is made that inadequate oil is being supplied from the main oil supply system based upon information from the main supply sensor.

BACKGROUND OF THE INVENTION

This application relates to an auxiliary oil system to supplement a main oil supply system on a gas turbine engine with a gear drive for a fan.

Gas turbine engines are known and, typically, include a fan delivering air into a bypass duct as propulsion air and also delivering air into a core engine. The core engine flow passes into a compressor where it is compressed and then delivered into a combustion section. The compressed air is mixed with fuel and ignited in the combustion section and products of this combustion pass downstream over turbine rotors driving them to rotate.

Historically, a turbine rotor drove the fan rotor at a single speed. This led to compromise in the desired speed for both the fan rotor and the turbine rotor. The fan rotor could not rotate unduly fast and, thus, the turbine rotor typically rotated slower than would be desired.

More recently, it has been proposed to include a gear reduction between a fan drive turbine and the fan rotor. This has allowed the fan to rotate at slower speeds and results in many efficiencies.

However, the gear reduction requires adequate lubrication and must be lubricated even under extreme flight conditions.

SUMMARY OF THE INVENTION

In a featured embodiment, a gas turbine engine includes a fan drive turbine, a fan rotor, and a gear reduction driven by the fan drive turbine and, in turn, to drive the fan rotor. A main oil supply system supplies oil to components within the gear reduction, and an auxiliary oil supply system. The auxiliary oil supply system includes a rotation sensor for sensing rotation of a component that will rotate with the fan rotor, a control, an auxiliary oil pump, and a main supply sensor for sensing operation of the main oil supply system. The control is programmed to supply oil from the auxiliary oil pump to the gear reduction when the rotation sensor senses the component is rotating. A determination is made that inadequate oil is being supplied from the main oil supply system based upon information from the main supply sensor.

In another embodiment according to the previous embodiment, the control controls an electric motor for the auxiliary oil pump.

In another embodiment according to any of the previous embodiments, the main supply sensor senses a pressure of the main oil supply system.

In another embodiment according to any of the previous embodiments, the rotation sensor is an optical sensor.

In another embodiment according to any of the previous embodiments, the main supply sensor senses a pressure of the main oil supply system.

In another embodiment according to any of the previous embodiments, the rotation sensor is an optical sensor.

In another embodiment according to any of the previous embodiments, the rotation sensor is an optical sensor.

In another embodiment according to any of the previous embodiments, the gear reduction includes a sun gear connected to the fan drive turbine to drive intermediate gears that engage a ring gear.

In another embodiment according to any of the previous embodiments, the sun gear, the intermediate gears and the ring gear are enclosed in a bearing compartment, to capture oil removed via a scavenge line connected to a main pump scavenge stage.

In another embodiment according to any of the previous embodiments, the gear reduction is surrounded by an oil gutter to scavenge oil and direct it to an auxiliary oil tank.

In another embodiment according to any of the previous embodiments, the auxiliary oil tank has an overflow conduit that allows excess oil to fall to the bottom of the bearing compartment.

In another embodiment according to any of the previous embodiments, the auxiliary oil tank has a tube with holes at a vertically higher location thereon, such that oil may be drawn from the auxiliary oil tank when it is full or under negative gravity conditions.

In another embodiment according to any of the previous embodiments, the auxiliary pump draws oil from a bottom of an oil sump and the bottom of the oil sump is at lower elevation than a line leading from the oil sump to the main pump scavenge stage.

In another embodiment according to any of the previous embodiments, the auxiliary pump also draws oil from the auxiliary oil tank.

In another embodiment according to any of the previous embodiments, the auxiliary oil system is operable to supply lubricant for at least 30 seconds at high power operation of the associated engine should the main oil supply system fail.

In another embodiment according to any of the previous embodiments, the auxiliary oil system being operable to allow the engine to operate under windmill conditions in the air for 90 minutes or longer.

In another embodiment according to any of the previous embodiments, the auxiliary oil system being operable to operate indefinitely on the ground when windmilling with wind speeds below 85 mph or less.

In another embodiment according to any of the previous embodiments, the auxiliary oil system being operable to fly with the engine in an aircraft under negative gravity conditions for at least 20 seconds.

In another embodiment according to any of the previous embodiments, the auxiliary oil system being operable to operate indefinitely on the ground when windmilling with wind speeds below 85 mph or less.

In another embodiment according to any of the previous embodiments, the auxiliary oil system being operable to fly with the engine in an aircraft under negative gravity conditions for at least 20 seconds.

DETAILED DESCRIPTION

FIG.2shows an oil supply system99for the gear reduction such as gear reduction48in the gas turbine engine20ofFIG.1. The gear reduction48includes a sun gear100which is driven by a fan drive turbine (such as turbine46ofFIG.1) and engages a plurality of intermediate gears102. In some embodiments, the intermediate gears102may be planet gears of a planetary epicyclic gear system. In other embodiments, the intermediate gears102may be star gears of a star epicyclic gear system. In some embodiments, the intermediate gears102, in turn, drive a ring gear103which drives a fan drive shaft to, in turn, rotate a fan (such as fan rotor42). Other gear arrangements would come within the scope of this application and the above is merely one example for a gear reduction which may be utilized to drive a fan rotor. For example, in other embodiments, a gear carrier (not shown) driven by intermediate gears may drive the fan shaft.

Oil supply104is shown schematically delivering oil to the planet gears102. It should be understood the oil is supplied to other components such as journal pins, bearings, etc. associated with the gear architecture illustrated inFIG.2.

A main oil supply system delivers oil to the gear architecture48. The main oil supply system may include any of a line106, a main oil supply pump108, a lubrication system110that includes filters, an oil tank142, and a line144. Oil is supplied from the line106delivered from the main oil supply pump108. A pressure stage of the main oil supply pump108receives oil from the oil tank142. The oil in the oil tank142feeds the main pump108, directs the oil through the line144, and is then conditioned in the lubrication system110that may contain filters to clean the oil and heat exchangers to cool the oil, as known. The oil then passes back to the gear architecture48through the line106.

A bearing compartment112surrounds the gear reduction48. The bearing compartment112has oil removed via a scavenge line180, which returns the oil to a scavenge side109of the main pump108, which, in turn, delivers the oil back to the oil tank142.

The gear architecture is surrounded by an oil gutter114, shown schematically, that scavenges oil from the gear architecture and directs it to an auxiliary tank116. When tank116is full, an overflow conduit117allows excess oil to fall to the bottom of the bearing compartment112. The gutter114is at least 70% efficient. This means that up to 30% of the oil falls out of the gutter and is scavenged by the scavenge side109of the main pump108through line180. The 70% that is captured in the gutter is directed into the tank116.

The detail of the oil supply104, the gutter114and the gears generally may be as shown in U.S. Patent Application 2008/0116010, now U.S. Pat. No. 8,215,454, issued Jul. 10, 2012. The details of those features are incorporated herein by reference.

An auxiliary oil pump124is shown, which will supply oil to the gear reduction84if the main oil supply system is not functioning, for whatever reason, or if the fan is being driven by windmill conditions. As described below, under many flight conditions, the main oil supply system may not be able to supply oil.

Thus, the auxiliary pump124is provided with an electric motor191. A power supply192is shown schematically as a battery, however, any source of electrical power on the engine or the associated aircraft may be utilized. A motion sensor190senses rotation of a fan, the low spool shaft, or a portion of the gear reduction. If rotation is sensed in either direction, then a determination is made that operation of the auxiliary oil pump124may become necessary. The motor191, motion sensor190, and power supply192all communicate with a control194. Control194also receives a pressure indicative of the operating status of the main oil supply pump108.

Control194may be part of the engine FADEC or may be a standalone controller. In general, the control is programmed such that if rotation is sensed by sensor190and the pressure in line144, measured through sensor140is indicative of the main oil pump108not providing adequate lubricant flow, then oil is supplied from the auxiliary pump124, as described below.

An inadequate lubricant flow may be described as oil flow that may result in degradation or loss of function of the gears in the gear reduction or the associated bearings that support the gears. As an example, if control194“sees” a pressure 50% below normal from sensor140during normal flight, then a determination might be made that inadequate oil is being provided by the main oil supply system. Of course other limits may be set aside from 50%. In an alternative example, if the control194sees zero pressure at sensor140on ground with rotation sensed by sensor190, then a determination might be made that the auxiliary oil supply system should supply oil to the gear reduction and the associated bearings. Sensors other than a pressure sensor may be utilized to sense the operation of the main oil supply system.

The term “determination” should be interpreted broadly. As an example, the sensor140could be a pressure responsive switch that sends an activation signal to the control should the pressure drop below a minimum. The control, upon receiving such a signal, is programmed to actuate the auxiliary oil supply system.

Broadly, all of these examples are “information” from the sensor supplied to the control.

The pump124draws oil from a sump126at a bottom of the compartment112through a line128. The sump126is at a lower elevation than the main scavenge line180and also draws oil from the tank116through the line122. Sump126will trap any residual oil in the bearing compartment112.

There are challenges with the auxiliary pump with regard to negative gravity conditions. Further, if there is a break in the main oil supply system or windmilling of the engine when the engine is otherwise shut down, it is desirable for the engine to be able to maintain operation for at least 30 seconds at power without damage if the main oil supply (108/106, etc.) ruptures or otherwise fails. This will provide a pilot time to shut the engine down.

It is also desirable to allow the engine to windmill in the air for 90 minutes or more without damage if it is shut down for other reasons than oil system failure. It is also desirable to allow the engine to windmill indefinitely, and at least twenty-four hours, on the ground with wind speeds above 10 mph and below about 85 mph. As known, windmilling refers to a condition where the engine is shut down, however, air being forced into the fan rotates the fan, in turn, causing components to rotate.

Also, it is desirable to allow an aircraft to fly under negative gravity conditions for at least 20 seconds.

All of these raise challenges with regard to operating the engine and supplying oil to the gear components.

The arrangement of the components, as described above, allow these conditions to be met.

The auxiliary pump124draws oil from the sump126. Pump124also draws oil from a line122. The tank116has a tube118with holes120, the tank116positioned at a vertically higher location relative to the auxiliary pomp124. The holes120are configured such that oil is only drawn from the tank116to the line122when it is full or under negative gravity conditions. Otherwise, oil is drained from the tank116by overflow through the conduit117.

Should the control determine that the pressure at line144, measured by sensor140is indicative of the main oil supply pump108not providing adequate lubricant, and the motion sensor190senses rotation of the engine, the valve132is opened to deliver oil from the auxiliary oil pump124to line200and then to line106, and feed the gear reduction to ensure that the conditions as described in this application are met. Line200is equipped with a one way check valve210, such that oil will only flow from line200to line106. In the event of rupture or malfunction of tank142, pump108or lubrication system110, oil will always be directed to the gear reduction and not spill out through a ruptured component.

In embodiments, the sensor190may be an optical sensor or any other rotation sensing system.

The conditions as described above are met in large part, since the auxiliary oil tank116, and the tube118, has the holes120only at the top, such that oil is only drawn from the tank116, through the line122when it is full, or under negative G conditions. Further, since the sump126is at a lower elevation than a main scavenge line180, the auxiliary pump124will always be supplied with oil, in both positive and negative G conditions. Further, the auxiliary pump124, in combination with the valve132, ensure that oil will be supplied in adequate amounts during the conditions set forth above.

Words such as “top” or “lower elevation” or anything relating to relative vertical positions should be understood to be taken relative to the positions the engine components will occupy when an aircraft associated with the gas turbine engine is on the ground.