Patent Description:
A speed reduction device, such as an epicyclical gear assembly, may be utilized to drive the fan section such that the fan section rotates at a speed different than the turbine section so as to increase the overall propulsive efficiency of the engine. In such engine architectures, a shaft driven by one of the turbine sections provides an input to the epicyclical gear assembly that drives the fan section at a reduced speed such that both the turbine section and the fan section can rotate at closer to optimal speeds.

The fan section includes a plurality of fan blades mounted to a hub supported by bearings for rotation about the engine axis. The hub is coupled to an output of the geared architecture. The bearings require lubricant that is supplied through lubricant passages. The geared architecture also requires lubricant. The structures required for communicating lubricant to the bearings and geared architecture can complicate assembly and require additional space.

Although geared architectures have improved propulsive efficiency, turbine engine manufacturers continue to seek further improvements to engine performance including improvements to thermal, transfer and propulsive efficiencies.

<CIT>discloses a prior art planetary gear system arrangement with an auxiliary oil system.

<CIT> discloses a prior art coupling system for a planetary gear train.

<CIT> discloses a prior art journal bearing arrangement.

According to the present invention, there is provided a gas turbine engine as set forth in claim <NUM>.

In an embodiment of the above, there is a lubricant recovery system for the planetary gear system which includes fluid passages that extend through the planetary gear system. A gutter is located radially outward from the planetary gear system for collecting lubricant. At least a portion of the gutter is rigidly attached to the ring gear.

In a further embodiment of any of the above, the ring gear includes a radially extending flange. At least a portion of the gutter is in direct contact with the radially extending flange on the ring gear.

In a further embodiment of any of the above, the gutter includes a forward portion and an aft portion. The forward portion of the gutter is located axially forward of the radially extending flange relative to an engine axis of the gas turbine engine. The aft portion is located axially aft of the radially extending flange relative to the engine axis.

In a further embodiment of any of the above, at least one of the intermediate gears is supported by a journal bearing and includes a pin that has a circumferentially extending slot in opposing axial ends for allowing the journal bearing to flex.

The fan section <NUM> drives air along a bypass flow path B in a bypass duct defined within a nacelle <NUM> while the compressor section <NUM> drives air along a core flow path C for compression and communication into the combustor section <NUM> then expansion through the turbine section <NUM>.

It should be understood that various bearing systems <NUM> at various locations may alternatively or additionally be provided and the location of bearing systems <NUM> may be varied as appropriate to the application.

Airflow through the core flow path C is compressed by the low pressure compressor <NUM> then the high pressure compressor <NUM>, mixed and burned with fuel in the combustor <NUM>, then expanded over the high pressure turbine <NUM> and low pressure turbine <NUM>.

The geared architecture <NUM> may be an epicycle gear train, such as a planetary gear system or other gear system, with a gear reduction ratio of greater than about <NUM>:<NUM>.

The fan section <NUM> of the engine <NUM> is designed for a particular flight condition -- typically cruise at about <NUM> Mach and about <NUM>,<NUM> feet (<NUM>,<NUM>). The flight condition of <NUM> Mach and <NUM>,<NUM> ft (<NUM>,<NUM>), with the engine at its best fuel consumption - also known as "bucket cruise Thrust Specific Fuel Consumption ('TSFC')" - is the industry standard parameter of lbm of fuel being burned divided by lbf of thrust the engine produces at that minimum point. In one example, the engine bypass ratio is determined at the TSFC conditions. "Low corrected fan tip speed" is the actual fan tip speed in ft/sec divided by an industry standard temperature correction of [(Tram °R) / (<NUM> °R)]<NUM> (wherein °R = K x <NUM>/<NUM>). The "Low corrected fan tip speed" as disclosed herein according to one non-limiting embodiment is less than about <NUM> ft/second (<NUM>/s).

The example gas turbine engine includes the fan <NUM> that comprises in one non-limiting embodiment less than about twenty-six (<NUM>) fan blades. In another non-limiting embodiment, the fan section <NUM> includes less than about twenty (<NUM>) fan blades. Moreover, in one disclosed embodiment the low pressure turbine <NUM> includes no more than about six (<NUM>) turbine rotors schematically indicated at <NUM>. In another non-limiting example embodiment the low pressure turbine <NUM> includes about three (<NUM>) turbine rotors. A ratio between the number of fan blades <NUM> and the number of low pressure turbine rotors is between about <NUM> and about <NUM>. The example low pressure turbine <NUM> provides the driving power to rotate the fan section <NUM> and therefore the relationship between the number of turbine rotors <NUM> in the low pressure turbine <NUM> and the number of blades <NUM> in the fan section <NUM> disclose an example gas turbine engine <NUM> with increased power transfer efficiency.

As shown in <FIG>, the gas turbine engine <NUM> includes a lubrication system <NUM> that supplies lubricant to the geared architecture <NUM>, a lubrication recovery system <NUM> to recover lubricant from the lubrication system <NUM>, and a support assembly <NUM> for supporting the geared architecture <NUM>.

The geared architecture <NUM> is located intermediate the fan <NUM> and the compressor section <NUM>. The geared architecture <NUM> is driven by a drive shaft flexible coupling 70a attached to the inner shaft <NUM> which is driven by the low pressure turbine <NUM>. The drive shaft flexible coupling 70a engages a sun gear <NUM> located radially inward from a plurality of intermediate gears <NUM> that are in engagement with the sun gear <NUM>. A forward end of the drive shaft flexible coupling 70a is joined to the sun gear <NUM> by a spline <NUM> to transfer rotatory motion from the inner shaft <NUM> to the sun gear <NUM>.

The intermediate gears <NUM> are supported by a carrier <NUM> that is attached to a fan drive shaft <NUM> through a torque shaft to rotate the fan <NUM>. Each of the intermediate gears <NUM> are supported by journal bearing assemblies <NUM>. The journal bearing assemblies <NUM> extend between and are mounted to opposite axial sides of the carrier <NUM>. A ring gear <NUM> is located radially outward of the intermediate gears <NUM>. The ring gear <NUM> engages the intermediate gears <NUM> on a radially inner side and is fixed to the engine static structure <NUM> on a radially outer side. In one embodiment, the sun gear <NUM>, the intermediate gears <NUM>, and the ring gear <NUM> are herringbone gears.

The ring gear <NUM> is attached to the engine static structure <NUM> with a ring gear flexible coupling 70b. The ring gear flexible couplings 70a, 70b allow movement of the ring gear <NUM> until the geared architecture <NUM> contacts a stop <NUM> on the engine static structure <NUM>.

The flexible couplings 70a, 70b each include a rigid spindle <NUM> and at least one flexible section <NUM> that forms an undulation. In the illustrated embodiment, each of the flexible couplings 70a, 70b include two flexible sections <NUM>. The flexible sections <NUM> extend radially outward from the rigid spindle <NUM> to form a ring with a diameter larger than a diameter of the rigid spindle <NUM>. The drive shaft flexible coupling 70a accommodates misalignment between the sun gear <NUM> and the inner shaft <NUM> and the ring gear flexible coupling 70b accommodates misalignment between the ring gear <NUM> and the engine static structure <NUM>. In this disclosure, axial or axially or radial or radially is in relation to the axis A of the gas turbine engine <NUM> unless stated otherwise.

<FIG> illustrates an enlarged view of a portion of the geared architecture <NUM> showing the intermediate gear <NUM> supported on the journal bearing assembly <NUM>. The journal bearing assembly <NUM> includes a pin <NUM> that extends through the intermediate gear <NUM> and is supported on opposing ends by the carrier <NUM>. The pin <NUM> includes an axially extending internal passages <NUM> and at least one radially extending internal passage <NUM>. The internal passages <NUM>, <NUM> supply lubricant from the lubrication system <NUM> to an interface between the pin <NUM> and a gear portion <NUM> of the intermediate gear <NUM>. The pin <NUM> includes a cylindrical portion <NUM> that extends axially between the opposing faces of the carrier <NUM> at least partially defining the axially extending internal passage <NUM>. A radially extending portion <NUM> extends radially outward from a central axial portion of the cylindrical portion <NUM>. A pair of winged portions <NUM> extend in opposing axial directions from the radially extending portion <NUM> and define circumferentially extending slots <NUM> between the winged portions <NUM> and the cylindrical portion <NUM>. A radially outer surface of the radially extending portion <NUM> and the pair of winged portions <NUM> form the bearing surface <NUM> facing the gear portion <NUM> of the intermediate gear <NUM>.

The combination of the pin <NUM> and the carrier <NUM> function to maintain the bearing surface <NUM> as linear as possible to reduce variation in contact between the bearing surface <NUM> and the gear portion <NUM> of the intermediate gear <NUM>. Because the winged portions <NUM> include a reduced thickness adjacent the slot <NUM>, the winged portions <NUM> are able to deflect radially inward in response to loading in the radially inward direction on the bearing surface <NUM>.

The lubrication system <NUM> provides lubricant to the bearing surface <NUM> through a series of passages. As shown in <FIG>, the lubrication system <NUM> provides lubricant to a lubricant inlet tube <NUM>. From the lubricant inlet tube <NUM>, lubricant travels into a feeder tube <NUM> to a transfer bearing assembly <NUM>. The feeder tube <NUM> extends through a spring spacer <NUM> that defines a spacing between a first bearing assembly <NUM> and the second bearing assembly <NUM> and provides a preload on the bearings assemblies <NUM>, <NUM>.

The feeder tube <NUM> includes a seal head portion <NUM> that fits within the transfer bearing assembly <NUM>. The transfer bearing assembly <NUM> includes openings that correspond with passages <NUM> through the torque shaft <NUM>. The passages <NUM> communicate lubricant supplied from the lubrication system <NUM> through the feeder tube <NUM> to an intermediate lubricant passage <NUM>. As appreciated, in this example, a single lubricant passage <NUM> is shown. However, a plurality of lubricant passages <NUM> may be utilized to communicate lubricant to different parts of the geared architecture <NUM>.

In this example, a lubricant manifold <NUM> is attached to the torque shaft <NUM> and rotates with the torque shaft <NUM> about the axis A. Lubricant provided through the feeder tube <NUM> passes through passages <NUM> within the torque shaft <NUM> to the intermediate lubricant passage <NUM>. From the intermediate lubricant passage <NUM>, lubricant is passed through a conduit <NUM> to passages <NUM> defined within the carrier <NUM>. The passages <NUM> direct the lubricant into the axially extending internal passage <NUM> in the journal bearing assembly <NUM>.

Once the lubricant enters the axially extending internal passage <NUM>, the lubricant will then be directed toward the radially extending passages <NUM>. The radially extending passages <NUM> direct the lubricant to the bearing surface <NUM> to provide lubricant between the pin <NUM> and the gear portion <NUM> of the intermediate gear <NUM>. The lubricant can then travel radially outward from the pin <NUM> to lubricate the interface between the intermediate gear <NUM> and the ring gear <NUM>. The lubricant is then recovered with the lubrication recovery system <NUM>. In one embodiment, the intermediate gears and the ring gear <NUM> include radially extending fluid passages to aid in transferring the lubricant through the geared architecture <NUM>.

Once the lubricant passes radially outward of the ring gear <NUM>, the lubricant collects on a forward gutter portion <NUM> and an aft gutter portion <NUM>. The gutter portions <NUM>, <NUM> are located radially outward from the ring gear <NUM> and are axially aligned with the geared architecture <NUM>. In the illustrated embodiment, the gutter portions <NUM>, <NUM> are U-shaped. The forward gutter portion <NUM> attaches directly to a radially extending flange <NUM> on the ring gear <NUM> on an axially forward side of the flange <NUM>. The aft gutter portion <NUM> attaches to an axially downstream side of the flange <NUM>. In the illustrated embodiment, the ring gear flexible coupling 70b attaches directly to the downstream side of the flange <NUM> and the aft gutter portion <NUM> directly contacts the ring gear flexible coupling 70b. In another embodiment, the aft gutter portion <NUM> and the flexible coupling 70b could be formed as single piece without a discontinuity separating the ring gear flexible coupling 70b from the aft gutter portion <NUM>.

A gutter sump passage <NUM> is located in at least one of the gutter portions <NUM>, <NUM> to allow the lubricant to travel radially outward through the gutter portions <NUM>, <NUM>. In the illustrated embodiment, the gutter sump passage <NUM> is located in the aft gutter portion <NUM>. However, the gutter sump passage <NUM> could be located on the forward gutter portion <NUM>. The gutter sump passage <NUM> directs the lubricant to a sump <NUM> to allow the lubricant to be reused in the gas turbine engine <NUM>.

Claim 1:
A gas turbine engine (<NUM>) comprising:
a planetary gear system (<NUM>) including a sun gear (<NUM>), intermediate gears (<NUM>), and a ring gear (<NUM>);
a carrier (<NUM>) attached to a fan drive shaft (<NUM>) through a torque shaft (<NUM>) to rotate a fan (<NUM>), wherein the intermediate gears (<NUM>) are supported by the carrier (<NUM>);
a ring gear flexible coupling (70b) connecting the ring gear (<NUM>) to an engine static structure (<NUM>); and
a sun gear flexible coupling (70a) connecting the sun gear (<NUM>) to a drive shaft (<NUM>);
wherein the ring gear flexible coupling (70b) and the sun gear flexible coupling (70a) define a lateral and transverse stiffness and a stop (<NUM>) on the engine static structure (<NUM>) limits movement of the planetary gear system (<NUM>),
characterized in that:
the gas turbine engine (<NUM>) includes a bypass ratio of greater than <NUM>; and
a lubricant manifold (<NUM>) is attached to the torque shaft (<NUM>) and rotates with the torque shaft (<NUM>) about an axis (A) of the engine (<NUM>), a feeder tube (<NUM>) is configured to provide lubricant through passages (<NUM>) within the torque shaft (<NUM>) to an intermediate lubricant passage (<NUM>), the intermediate lubricant passage configured to pass lubricant through a conduit (<NUM>) to passages (<NUM>) defined within the carrier (<NUM>).