Patent Description:
A typical aircraft engine has a lubrication system to meet the lubrication and cooling needs of various components of the engine. The lubrication system can deliver oil from an oil tank to the various components within the engine, recover the used oil from the components, and return the recovered used oil back to the oil tank for recirculation. The arrangement of the pumps of the lubrication system of an aircraft engine can be bulky and require complex and/or cumbersome plumbing. Improvement is desirable.

A prior art lubrication system, having the features of the preamble of claim <NUM>, is disclosed in <CIT>.

An aspect of the present invention provides a lubricant pump system for an aircraft engine in accordance with claim <NUM>.

In another aspect, the present invention provides a method of driving lubricant pumps of an aircraft engine in accordance with claim <NUM>.

In a further aspect, the present invention provides an aircraft engine in accordance with claim <NUM>.

In some embodiments of the above aircraft engine, the supply pump is one of a plurality of supply pumps drivingly connected to the source of motive power via the first drivetrain; and the scavenge pump is one of a plurality of scavenge pumps drivingly connected to the source of motive power via the second drivetrain.

In further embodiments of any of the above embodiments of the aircraft engine, the source of motive power includes a drive gear; the first drivetrain includes a first shaft drivingly connected to the drive gear via the frangible connection; and the second drivetrain includes a second shaft drivingly connected to the drive gear via the frangible connection.

In further embodiments of any of the above embodiments of the aircraft engine, the aircraft engine comprises a coupler drivingly connecting the first shaft and the second shaft together, wherein the coupler is drivingly connected to the drive gear via the frangible connection.

In further embodiments of any of the above embodiments of the aircraft engine, the drive gear is rotatable about an axis; the drive gear has a through central bore extending along the axis; the central bore has a first opening and a second opening axially opposite the first opening; the first drivetrain extends through the first opening of the central bore of the drive gear; and the second drivetrain extends through the second opening of the central bore of the drive gear.

The following disclosure describes lubrication systems of aircraft engines and methods of operating such lubrication systems. In some embodiments, the systems and methods described herein may promote safe utilization an efficient packaging (i.e., use of space) of lubricant pumps associated with an aircraft engine. In some embodiments, the systems and methods described herein may promote simplified plumbing by, for example, segregating lubricant supply lines of supply pumps from lubricant return lines of scavenge pumps. In some embodiments, the systems and methods described herein may be configured to, as a fail-safe, automatically stop one or more supply pumps in the event of a malfunction of one or more scavenge pumps. This may cause lubricant supply to a lubrication load from which the lubricant is no longer being recovered to be reduced or stopped. In some situations, this may potentially impede an escalation of the malfunction by stopping flammable lubricant from being supplied to a region of the aircraft engine potentially prone to cause ignition of the lubricant for example.

The terms "engaged", "connected" or "coupled" may include both direct engagement, connection or coupling (in which two elements contact each other) and indirect engagement, connection or coupling (in which at least one additional element is located between the two elements).

The term "substantially" as used herein may be applied to modify any quantitative representation which could permissibly vary without resulting in a change in the basic function to which it is related.

<FIG> shows a schematic representation of aircraft engine <NUM> (referred hereinafter as "engine <NUM>"). Engine <NUM> is illustrated as a turbofan gas turbine engine as an example. However, it is understood that the systems and methods described herein are also applicable to other types of aircraft engines such as turboshaft and turboprop gas turbine engines for fixed-wing and/or rotary wing aircraft applications for example. Engine <NUM> may suitable for use in (e.g., subsonic flight) aircraft applications. Engine <NUM> may include, in serial flow communication, fan <NUM> through which ambient air is propelled, multistage compressor <NUM> for pressurizing the air, combustor <NUM> in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and turbine section <NUM> for extracting energy from the combustion gases.

Engine <NUM> may include lubricant pump system <NUM> (referred hereinafter as "system <NUM>"), which may be part of a lubrication system of engine <NUM> for servicing one or more lubrication loads <NUM> (referred hereinafter in the singular) of engine <NUM>. Lubrication load <NUM> may include one or more bearings and/or gears that require lubrication and/or cooling. System <NUM> may include lubricant tank <NUM> and one or more supply pressure lubricant pumps <NUM> (referred hereinafter in as "supply pump(s) <NUM>") in fluid communication with lubricant tank <NUM>. Supply pump(s) <NUM> may be operatively connected to supply lubricant (e.g., lubricating fluid, oil) from lubricant tank <NUM> to lubrication load <NUM> of engine <NUM>.

System <NUM> may include one or more scavenge lubricant pumps <NUM> (referred hereinafter as "scavenge pump(s) <NUM>") that may drive (i.e., recover) used lubricant collected in one or more sumps of engine <NUM> back to lubricant tank <NUM> for recirculation. It is understood that some embodiments of system <NUM> may include additional components than those illustrated herein. Supply pump(s) <NUM> and scavenge pump(s) <NUM> may include gear type, gear-rotor type or other suitable type of pumps.

Supply pump(s) <NUM> and scavenge pump(s) <NUM> may be driven by any suitable source of motive power available such as electric motor(s), hydraulic motor(s), pneumatic motor(s) and/or one or more rotating/driven shafts of engine <NUM> being drivingly connected to supply pump(s) <NUM> and/or to scavenge pump(s) <NUM> via accessory gearbox <NUM> (referred hereinafter as "AGB <NUM>") for example. In some embodiments as shown in <FIG>, a single output (output pad) of AGB <NUM> may be used as a source of motive power (e.g., an input torque) to drive supply pump(s) <NUM> and scavenge pump(s) <NUM>.

In some embodiments of system <NUM>, supply pump(s) <NUM> and scavenge pump(s) <NUM> may be driven by AGB <NUM> via separate respective drivetrains 32A, 32B defining separate load paths. First drivetrain 32A and second drivetrain 32B may each include one or more shafts, gear(s), coupling(s), link(s), joint(s) and/or other components suitable for transferring (e.g., rotational) motive power. First drivetrain 32A may define a first load path receiving a first portion of the motive power from AGB <NUM> for driving supply pump(s) <NUM>, and second drivetrain 32B may define a second load path receiving a second portion of the motive power for driving scavenge pump(s) <NUM>. In other words, the motive power transferred to system <NUM> from AGB <NUM> may be divided (i.e., split) between the first load path defined by first drivetrain 32A and the second load path defined by second drivetrain 32B. The first load path defined by first drivetrain 32A, and the second load path defined by second drivetrain 32B may be separate from each other. The first portion of motive power transferred to the first load path may be different from the second portion of motive power transferred to the second load path. In other words, first drivetrain 32A and second drivetrain 32B may be configured as separate branches that drive different pumps (e.g., pump stacks) using different portions of the motive power input into system <NUM> from AGB <NUM> or otherwise.

The input motive power or input torque received at system <NUM> may be received via a suitable mechanical fuse <NUM> (referred hereinafter as "fuse <NUM>") operatively disposed between the source of motive power and both the first and second load paths defined by first drivetrain 32A and second drivetrain 32B. Both first drivetrain 32A and second drivetrain 32B may be drivingly connected to the source of motive power via a single common fuse <NUM> so that an obstruction in first drivetrain 32A or in second drivetrain 32B may cause fuse <NUM> to break and simultaneously cause first drivetrain 32A and second drivetrain 32B to become drivingly disconnected from the source of motive power. Consequently, in the event of a malfunction of scavenge pump(s) <NUM>, such as scavenge pump(s) <NUM> becoming seized or exhibiting an increased resistance to being driven via second drivetrain 32B, the breaking of fuse <NUM> would cause the driving of scavenge pump(s) <NUM> and of supply pump(s) <NUM> to cease. Similarly, in the event of a malfunction of supply pump(s) <NUM>, such as supply pump(s) <NUM> becoming seized or exhibiting an increased resistance to being driven via first drivetrain 32A, the breaking of fuse <NUM> would cause the driving of scavenge pump(s) <NUM> and of supply pump(s) <NUM> to cease.

Fuse <NUM> may include any suitable frangible connection(s) suitable for transmitting motive power during normal operation of scavenge pump(s) <NUM> and supply pump(s) <NUM>, and may be configured (e.g., designed, sized) to break/fail in the event of the motive power or torque being transferred exceeding a threshold indicative of a malfunction in first drivetrain 32A and/or in second drivetrain 32B. Fuse <NUM> may be of a type known as a "torque fuse". For example, fuse <NUM> may be sized to break/fail in the event of a malfunction of a single scavenge pump <NUM> or of a single supply pump <NUM>. Fuse <NUM> may be a mechanical sacrificial part designed to break in the event of a malfunction that increases the resistance to rotational movement transferred to first drivetrain 32A and/or to second drivetrain 32B. In various embodiments, fuse <NUM> may include a shear pin, a shear neck, and/or a (e.g., Woodruff) key for example.

<FIG> is a schematic representation of another exemplary lubricant pump system <NUM> (referred hereinafter as "system <NUM>") that may be part of a lubrication system of engine <NUM>. Aspects of system <NUM> may be combined with other systems described herein. System <NUM> may include components of system <NUM> described above and like elements have been identified using reference numerals that have been incremented by <NUM>.

Input torque T may be received from AGB <NUM> or other source of motive power and may be divided between the first load path defined by first drivetrain 132A and the second load path defined by second drivetrain 132B. Input torque T may be received and transferred to first drivetrain 132A and to second drivetrain 132B via fuse <NUM>. Input torque T may be split into first torque portion TA delivered to first drivetrain 132A, and second torque portion TB delivered to second drivetrain 132B. First drivetrain 132A may be used to drive one or more supply pumps 126A and optionally one or more scavenge pumps 128A. Second drivetrain 132B may be used to drive one or more scavenge pumps 128B and optionally one or more supply pumps 126B. In various embodiments, first drivetrain 132A may be used to drive supply pump(s) 126A exclusively, or may be used to drive a combination of supply pump(s) 126A and scavenge pump(s) 128A. Similarly, in various embodiments, second drivetrain 132B may be used to drive scavenge pump(s) 128B exclusively, or may be used to drive a combination of scavenge pump(s) 128B and supply pump(s) 126B. In some embodiments, the pumps driven by first drivetrain 132A may be arranged serially along the first load path. In some embodiments, the pumps driven by second drivetrain 132B may be arranged serially along the second load path.

In some embodiments, input torque T may be transferred to first drivetrain 132A and second drivetrain 132B via coupler <NUM>. Coupler <NUM> may include any suitable structure suitable to transfer motive power (e.g., input torque T) to both first drivetrain 132A and second drivetrain 132B. In other words, coupler <NUM> may serve to drivingly couple first drivetrain 132A and second drivetrain 132B to input torque T. In some embodiments, coupler <NUM> may include a suitable torque splitter capable of dividing input torque T into first torque portion TA delivered to first drivetrain 132A and second torque portion TB delivered to second drivetrain 132B. In some embodiments, coupler <NUM> may include a torque dividing gearbox having an input and two outputs for respectively driving first drivetrain 132A and second drivetrain 132B. In various embodiments, first torque portion TA delivered to first drivetrain 132A and second torque portion TB delivered to second drivetrain 132B may be substantially equal or may be different depending on the configuration of coupler <NUM> and on the number and type(s) of pumps that are driven by each of first drivetrain 132A and second drivetrain 132B. In some embodiments, coupler <NUM> may be configured as coupler <NUM> shown in <FIG> and described below.

Even though system <NUM> of <FIG> only shows two drivetrains respectively driving two pump stacks, it is understood that system <NUM> could include one or more additional drivetrains that are used to drive one or more additional pump stacks via fuse <NUM> using input torque T. In other words, input torque T and fuse <NUM> could be used to drive two or more drivetrains each driving one or more lubricant (e.g., supply and/or scavenge) pumps.

<FIG> is a schematic representation of another exemplary lubricant pump system <NUM> (referred hereinafter as "system <NUM>") that may be part of a lubrication system of engine <NUM>. Aspects of system <NUM> may be combined with other systems described herein. System <NUM> may include components of systems <NUM> and <NUM> described above. Like elements from system <NUM> have been identified using reference numerals that have been incremented by <NUM>.

In some embodiments of system <NUM>, the source of motive power may include drive gear <NUM>, which may include an external toothed face receiving input torque T. Input torque T may be delivered to drive gear <NUM> from AGB <NUM> (shown in <FIG>) or from another source of motive power and may be divided between the first load path defined by first drivetrain 232A and the second load path defined by second drivetrain 232B.

Input torque T may be transferred from drive gear <NUM> to first drivetrain 232A and to second drivetrain 232B via fuse <NUM>. Input torque T may be split into first torque portion TA delivered to first drivetrain 232A and second torque portion TB delivered to second drivetrain 232B. First drivetrain 132A may be used to drive one or more supply pumps 226A and/or one or more scavenge pumps 228A. Second drivetrain 232B may be used to drive one or more scavenge pumps 228B and/or one or more supply pumps 226B.

Drive gear <NUM> may be rotatable about rotation axis RA. Drive gear <NUM> may be rotatably supported by a suitable structure of engine <NUM> via one or more bearings <NUM>. In some embodiments, input torque T may be transferred to first drivetrain 232A and to second drivetrain 232B via coupler <NUM>. Drive gear <NUM> may have a through central bore <NUM> extending along rotation axis RA. Central bore <NUM> may have first opening 244A, and second opening 244B axially opposite first opening 244A. The first load path defined by first drivetrain 232A may extend through first opening 244A of central bore <NUM> of drive gear <NUM>. For example, first shaft 246A of first drivetrain 232A may extend into central bore <NUM> via first opening 244A and may be drivingly connected to coupler <NUM>. Similarly, the second load path defined by second drivetrain 232B may extend through second opening 244B of central bore <NUM> of drive gear <NUM>. For example, second shaft 246B of second drivetrain 232B may extend into central bore <NUM> via second opening 244B and may be drivingly connected to coupler <NUM>.

Coupler <NUM> may be disposed inside central bore <NUM> of drive gear <NUM>. In some embodiments, an axial position of coupler <NUM> relative to rotation axis RA may axially overlap an axial position of one or more bearings <NUM>. In some embodiments, coupler <NUM> may have an annular (e.g., sleeve) configuration. For example, a radially-outer portion of coupler <NUM> may be drivingly connected with a radially-inner portion of drive gear <NUM> via fuse <NUM>. In some embodiments, fuse <NUM> may define a frangible connection establishing torque transfer between coupler <NUM> and drive gear <NUM>. In some embodiments, fuse <NUM> may include a Woodruff or other type of key that is engaged with both coupler <NUM> and with drive gear <NUM>. Other types of frangible connections may be suitable.

Coupler <NUM> may be drivingly connected to both first shaft 246A and second shaft 246B. First shaft 246A of first drivetrain 232A may be drivingly connected to a first radially-inner portion of coupler <NUM>. Second shaft 246B of second drivetrain 232B may be drivingly connected to a second radially-inner portion of coupler <NUM>. The first and second radially-inner portions of coupler <NUM> may be axially-opposite radially-inner portions of coupler <NUM>. In some embodiments, first shaft 246A and second shaft 246B may be drivingly connected to coupler <NUM> via one or more splined or other type of connections. The arrangement shown in <FIG> may result in the first load path defined by first drivetrain 232A, and the second load path defined by second drivetrain 232B being drivingly connected to drive gear <NUM> (and input torque) via the same fuse <NUM>.

In some embodiments of system <NUM>, first shaft 246A and second shaft 246B may be drivingly connected via coupler <NUM> for common rotation. In some embodiments of system <NUM>, first shaft 246A and second shaft 246B may be drivingly connected for common rotation with drive gear <NUM>. In some embodiments of system <NUM>, first shaft 246A, second shaft 246B, coupler <NUM>, fuse <NUM> and drive gear <NUM> may be drivingly connected for common rotation. In some embodiments, first shaft 246A may be coaxial with second shaft 246B. In some embodiments, first shaft 246A and second shaft 246B may be coaxial with drive gear <NUM>.

<FIG> is a flow diagram of a method <NUM> of driving lubricant pumps of engine <NUM> or of another aircraft engine. Aspects of method <NUM> may be combined with other aspects or actions disclosed herein. Aspects of systems <NUM>, <NUM> and <NUM> may be incorporated into method <NUM>. In various embodiments, method <NUM> may include:.

In some embodiments of method <NUM>, the first lubricant pump may be supply pump <NUM> and the second lubricant pump may be scavenge pump <NUM>.

Input torque T may be received via fuse <NUM>. Ceasing to drive the first lubricant pump and the second lubricant pump using input torque T may include causing fuse <NUM> to break.

A malfunction of the second lubricant pump includes seizing of the second pump. Ceasing to drive the first lubricant pump and the second lubricant pump using input torque T may include disconnecting the first load path and the second load path from input torque T.

In some embodiments, method <NUM> may include substantially simultaneously disconnecting the first load path and the second load path from input torque T when the malfunction of the second (or first) lubricant pump occurs.

The embodiments described in this document provide non-limiting examples of possible implementations of the present invention.

Claim 1:
A lubricant pump system (<NUM>; <NUM>; <NUM>) for an aircraft engine (<NUM>), the lubricant pump system (<NUM>; <NUM>; <NUM>) comprising:
a source of motive power (<NUM>; <NUM>);
a first lubricant pump (<NUM>; 126A, 128A; 226A, 228A) drivingly connected to the source of motive power (<NUM>; <NUM>) via a first load path (32A; 132A; 232A) receiving a first portion of the motive power;
a second lubricant pump (<NUM>; 128B, 126B; 228B, 226B) drivingly connected to the source of motive power (<NUM>; <NUM>) via a second load path (32B; 132B; 232B) receiving a second portion of the motive power, the second load path (32B; 132B; 232B) being separate from the first load path (32A; 132A; 232A); and
a mechanical fuse (<NUM>; <NUM>; <NUM>) operatively disposed between the source of motive power (<NUM>; <NUM>) and the first load path (32A; 123A; 232A), the mechanical fuse (<NUM>; <NUM>; <NUM>) also being operatively disposed between the source of motive power (<NUM>) and the second load path (32B; 132B; 232B),
characterised in that:
the source of motive power (<NUM>; <NUM>) includes a drive gear (<NUM>), the first load path (232A) includes a first shaft (246A) drivingly connected to the drive gear (<NUM>) via the mechanical fuse (<NUM>), and the second load path (232B) includes a second shaft (246B) drivingly connected to the drive gear (<NUM>) via the mechanical fuse (<NUM>); and
the lubricant pump system comprises a coupler (<NUM>) drivingly interconnecting the first shaft (246A) and the second shaft (246B) together, the coupler (<NUM>) being drivingly connected to the drive gear (<NUM>) via the mechanical fuse (<NUM>).