US20090078508A1

Movatterモバイル変換

Info

Publication number: US20090078508A1
Application number: US11/858,738
Authority: US
Inventors: Jim E. Delaloye
Original assignee: Honeywell International Inc
Current assignee: Honeywell International Inc
Priority date: 2007-09-20
Filing date: 2007-09-20
Publication date: 2009-03-26
Also published as: EP2039891A2; EP2039891A3

Abstract

A system and method for controlling lubricant displacement from a lubrication system and a rotating machine includes supplying a gaseous fluid to the lubrication supply system to displace the lubricant. The gaseous fluid is preferentially directed through a first section of the lubrication supply system and to the rotating machine, and is at least inhibited from flowing through a second section of the lubrication supply system. As a result, the gaseous fluid displaces the lubricant in the rotating machine and in the first section of the lubrication supply system, while the second section of the lubrication supply system remains at least substantially full of lubricant.

Description

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with Government support under Contract No. N00019-02-C-3002, awarded by the U.S. Navy. The Government has certain rights in this invention.

TECHNICAL FIELD

The present invention relates to rotating machine lubrication and, more particularly, to a system and method for controlling lubricant removal from the rotating machine and the machine lubrication supply system during shutdown of the machine.

BACKGROUND

Many aircraft gas turbine engines are supplied with lubricant from a pump driven lubrication supply system. In particular, the lubrication supply pump, which may be part of a pump assembly having a plurality of supply pumps on a common, engine-driven or electric motor driven shaft, draws lubricant from a lubricant reservoir, and increases the pressure of the lubricant. The lubricant is then delivered, via an appropriate piping circuit, to the engine. The lubricant is directed, via appropriate flow circuits within the engine, to the various components that may need lubrication, and is collected in one or more recovery sumps in the engine. One or more of the pump assembly pumps then draws the lubricant that collects in the recovery sumps and returns the lubricant back to the reservoir.

When an aircraft gas turbine engine is shutdown, the lubricant is typically removed and returned to the reservoir to reduce the viscous drag due to residual lubricant on rolling and sliding lubricated surfaces during a subsequent startup. In many instances this is accomplished by actuating a valve that, when appropriately positioned, allows the supply pumps to draw air, rather than lubricant, into the system. The supply pumps direct the air into the supply system and engine, displacing the lubricant therefrom, and directing the displaced lubricant back to the lubricant reservoir.

Although the above-described systems and methods are generally safe, reliable, and robust, theses systems and methods do suffer certain drawbacks. For example, during a subsequent cold engine and lubrication system startup, after the lubricant has been removed from the lubrication system and engine, the lubrication system and engine are first refilled with lubricant before lubricant pressure rises sufficiently to force lubricant into some engine components. Because lubricant is removed from the entire lubrication system during the engine shutdown sequence, the subsequent startup can use an undesired amount of power and take an undesired amount of time to raise lubricant pressure sufficiently high.

Hence, there is a need for lubricant supply system and method that can remove lubricant from a rotating machine during shutdown of the machine and supply system, while decreasing the amount of power and time needed to raise lubricant pressure during a subsequent startup of the supply system and machine. The present invention addresses at least this need.

BRIEF SUMMARY

In one embodiment, and by way of example only, an aircraft lubrication supply system includes a motor, a pump, a fluid supply line, a fluid bypass line, and a controller. The motor is coupled to be selectively energized from a power bus and is operable, upon being energized, to rotate at a rotational speed and supply a drive force. The pump has at least a fluid inlet and a fluid outlet, is coupled to receive the drive force from the motor and is configured, in response thereto, to draw fluid into the fluid inlet from either a lubricant source or a gaseous fluid source, and to discharge the fluid via the fluid outlet. The fluid supply line is coupled to the fluid outlet and is configured to supply the fluid discharged from the fluid outlet to a rotating machine. The fluid bypass line has an inlet and an outlet. The fluid bypass line inlet is coupled to the fluid supply line at a first location, and the fluid bypass line outlet is coupled to the fluid supply line at a second location that is downstream of the first location. The bypass control valve is disposed between the fluid bypass line inlet and the fluid bypass line outlet, and is operable to control fluid flow at least through the fluid bypass line. The controller is configured to couple to the power bus and to receive a machine de-lube signal that indicates the rotating machine is being de-lubricated. The controller is operable, upon receipt of the machine de-lube signal, to controllably energize the motor from the power bus to thereby displace at least a substantial volume of lubricant in the fluid supply line and the rotating machine with fluid from the gaseous fluid source, and to cause the bypass control valve to move to a position that results in the fluid bypass line remaining at least substantially full of lubricant when the at least substantial volume of lubricant is displaced from the fluid supply line and the rotating machine.

In another exemplary embodiment, a method of removing lubricant from a lubrication supply system and a rotating machine supplied with lubricant by the lubrication supply system includes supplying a gaseous fluid to the lubrication supply system to displace the lubricant. The gaseous fluid is preferentially directed through a first section of the lubrication supply system and to the rotating machine, and is at least inhibited from flowing through a second section of the lubrication supply system. As a result, the gaseous fluid displaces the lubricant in the rotating machine and in the first section of the lubrication supply system, while the second section of the lubrication supply system remains at least substantially full of lubricant.

Other independent features and advantages of the preferred lubrication supply system and method will become apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1, which is the sole FIGURE, is a schematic diagram of an aircraft lubrication supply system according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The following detailed description is merely exemplary in nature and is not intended to limit the invention or its application and uses. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description. In this regard, although the system is depicted and described as supplying lubricant to a turbomachine, it will be appreciated that the invention is not so limited, and that the system and method described herein may be used to supply lubricant to any one of numerous airframe mounted rotating machines.

With reference now toFIG. 1, a schematic diagram of an exemplary aircraftlubrication supply system100 is depicted, and includes areservoir102, apump assembly104, amotor106, and acontroller108. Thereservoir102 is used to store a supply oflubricant112 such as, for example, oil or other suitable hydraulic fluid. Alevel sensor114 and atemperature sensor116 are installed within, or on, thereservoir102. Thelevel sensor114 senses the level of lubricant in thereservoir102 and supplies a level signal representative of the sensed level to thecontroller108. Thetemperature sensor116 senses the temperature of the lubricant in thereservoir102 and supplies a temperature signal representative of the sensed temperature to thecontroller108. It will be appreciated that thelevel sensor114 and thetemperature sensor116 may be implemented using any one of numerous types of level and temperature sensors, respectively, that are known now or that may be developed in the future.

Thepump assembly104, at least in n the depicted embodiment, includes a plurality ofsupply pumps118 and a plurality ofreturn pumps122. Thesupply pumps118 each include afluid inlet117 and afluid outlet119. Thesupply pumps118, when driven, draw fluid from one of two fluid sources, and discharge the fluid, at an increased pressure, into afluid supply conduit124. The fluid supply conduit124, among other potential functions, supplies the lubricant to one or more rotating machines. Although one or more various types of machines could be supplied with the lubricant, in the depicted embodiment the lubricant is supplied to a rotating turbomachine. It will be appreciated that each of the

pumps

118,122 that comprise thepump assembly104 could be implemented as any one of numerous types of centrifugal or positive displacement type pumps, but in the preferred embodiment each

pump

118,122 is implemented as a positive displacement pump.

The two fluid sources from which thesupply pumps118 may draw fluid include thereservoir102 and agaseous fluid source126. Thegaseous fluid source126 may be configured as any one of numerous sources of gaseous fluid, but in the depicted embodiment it is configured as an air source. Preferably, the surrounding environment acts as a suitable air source. If not, however, a dedicated source of a suitable gas may be used. The specific source from whence thesupply pumps118 draw fluid may be controlled by, for example, ade-lube control valve128. It will be appreciated that the de-lubecontrol valve128 may be implemented using any one of numerous types of valves to. In the depicted embodiment, however, thede-lube control valve128 is implemented as a solenoid-operated valve.

AsFIG. 1 also depicts, alubricant filter132 may also be disposed within thelubricant supply conduit124. Thelubricant filter132 removes any particulate or other debris that may be present in lubricant before it is supplied to the rotating machine. Afilter bypass valve134, and appropriate bypass piping136, are disposed in parallel with thelubricant filter132. Thebypass valve134 is configured such that it is normally in a closed position, and moves to the open position when a predetermined differential pressure exists across it. Thus, if thelubricant filter132 becomes clogged and generates a sufficiently high differential pressure, thebypass valve134 will open to ensure a sufficient flow of lubricant to the rotating machine is maintained.

Thelubricant supply conduit132 also includes a pair of pressure sensors, a filterinlet pressure sensor138 and a filteroutlet pressure sensor142. The

pressure sensors

138,142 are each operable to sense lubricant pressure and to supply a pressure signal representative of the sensed pressure to thecontroller108. As the assigned nomenclature connotes, the filterinlet pressure sensor138 senses lubricant pressure at the inlet to thelubricant filter132, and the filteroutlet pressure sensor142 senses lubricant pressure at the outlet of thelubricant filter132. It will be appreciated that the depicted configuration is merely exemplary of a particular embodiment, and that thesystem100 could be implemented with more or less than this number of pressure sensors. For example, thesystem100 could be implemented with only the filterinlet pressure sensor138 or only the filteroutlet pressure sensor142, with a plurality of filterinlet pressures sensors138 and filteroutlet pressure sensors142, or with no pressure sensors.

The temperature of the lubricant that is supplied to the rotating machine is controlled, at least partially, via afluid bypass line144 and abypass control valve146. Thefluid bypass line144 includes aninlet148 and anoutlet152. The fluidbypass line inlet148 is coupled to thefluid supply line124 at a first location, and the fluidbypass line outlet152 is coupled to thefluid supply line124 at a second location downstream of the first location. Aheat exchanger154 is disposed in thefluid bypass line144. Fluid in thebypass line144 and fluid from asecond fluid system175 flow into and through theheat exchanger154. In theheat exchanger154, heat is transferred between the two fluids. Duringnormal system100 operation, heat is typically transferred from the fluid (e.g., lubricant) in thefluid bypass line144 to the fluid from thesecond fluid system175, thereby cooling the fluid in thefluid bypass line144. The cooled fluid then flows back into thefluid supply line124. The amount of fluid (if any) that flows into and through thefluid bypass line144 is controlled via thebypass control valve146, embodiments of which will now be briefly described.

Thebypass control valve146 is disposed in thefluid supply line124 between the fluidbypass line inlet148 and the fluidbypass line outlet152. Thebypass control valve146 is operable to control fluid flow at least through thefluid bypass line144. More specifically, in the depicted embodiment, thebypass control valve146 is movable between a closed position and an open position. When thebypass control valve146 is in the closed position, all of the fluid discharged from the supply pumps118 will flow into and through thefluid bypass line144. Conversely, when thebypass control valve146 is in the open position, most (if not all) of the fluid discharged from the supply pumps118 will flow through thebypass control valve146, and only a portion (if any) of the fluid will flow into and through thefluid bypass line144.

From the above discussion, it may thus be appreciated that during normal system operations thebypass control valve146 is preferably positioned to regulate the temperature of the lubricant supplied to the rotating machine. That is, if the lubricant discharged from the supply pumps118 is below a predetermined temperature, then thebypass control valve146 will be open and only a portion (if any) of the discharged lubricant discharged will flow into and through thefluid bypass line144. If, however, the lubricant discharged from the supply pumps118 reaches or exceeds a predetermined set temperature, then thebypass control valve146 will close and all of the fluid discharged from the supply pumps118 will flow into and through thefluid bypass line144, and be cooled in theheat exchanger154.

Before proceeding further it is noted that thebypass control valve146 may be variously disposed and variously configured. For example, and as is depicted in phantom inFIG. 1, rather than being disposed in thesupply line124, thebypass control valve146 could be disposed in thefluid bypass line144. Moreover, thebypass control valve146 could be implemented using any one of numerous suitable devices, and be configured to move between the closed and open positions based on various sensed temperatures. For example, in the depicted embodiment thebypass control valve146 is implemented using a thermally actuated valve, such as a eutectic-based actuator operated valve, that moves a valve element between the closed and open position based on the temperature of the actuator. With this type of valve, the actuator temperature varies with fluid temperature at the outlet of thebypass control valve146 and, based on this temperature, controls the position of the valve element. In other embodiments, the fluid temperature at the inlet of thebypass control valve146 could be used. In addition, a fluid temperature sensor could be included to sense fluid temperature at one or more locations in thefluid supply line124 and the sensed temperature could be used to control an electric, hydraulic, or pneumatic actuator, or various other actuator types, to move thebypass control valve146 between the closed and open positions.

No matter the specific configuration of thebypass control valve146, it is noted that the lubricant that is ultimately supplied to the rotating machine flows to various components within the machine and is collected in one or more sumps in the rotating machine. The lubricant that is collected in the rotating machine sumps is then returned to thereservoir102 for reuse. To do so, a plurality of the above-mentioned return pumps122 draws used lubricant from the rotating machine sumps and discharges the used lubricant back into thereservoir102 for reuse. It will be appreciated that the configuration of thepump assembly104 described herein is merely exemplary, and that thepump assembly104 could be implemented using any one of numerous other configurations. For example, thepump assembly104 could be implemented with asingle supply pump118 and asingle return pump122, or with just one or more supply pumps118. No matter how many supply or return

pumps

118,122 are used to implement thepump assembly104, it is seen that each

pump

118,122 is mounted on a commonpump assembly shaft148 and is driven via a drive force supplied from themotor106.

Themotor106 is selectively energized from apower bus115 and, when energized, rotates at a speed controlled by thecontroller108 to thereby supply the drive force to thepump assembly104. In the depicted embodiment themotor106 is directly coupled to thepump shaft148 and thus rotates the pump shaft148 (and thus thepumps118,122) at the motor speed. It will be appreciated, however, that themotor106, if needed or desired, could be coupled to thepump shaft148 via one or more gear assemblies, which could be configured to either step up or step down the motor speed. It will additionally be appreciated that themotor106 could be implemented as any one of numerous types of AC or DC motors, but in a particular preferred embodiment themotor106 is implemented as a brushless DC motor.

As noted above, themotor106 is selectively energized from thepower bus115 under the control of thecontroller108. Thecontroller108 implements control logic via, for example, acentral processing unit152. The control logic that thecontroller108 implements during operation of the rotating machine may differ from the control logic implemented during a shutdown sequence of the rotating machine. For example, during operation of the rotating machine the control logic may implement a predefined schedule of lubricant supply pressure as a function of various conditions. More specifically, thecontroller108 may receive signals representative of various parameters. In response to these signals, the control logic in thecontroller108 may determine the scheduled lubricant supply pressure based on these parameters, and control themotor106 to rotate at least the supply pumps118 at a speed that will supply lubricant from thereservoir102 at the scheduled lubricant supply pressure. Conversely, during the shutdown sequence, the control logic may control the rotational speed of themotor106 in accordance with a schedule that will displace at least a substantial volume of the lubricant in the rotating machine with air from the gaseousfluid source126. Although thecontroller108 is depicted using a single function block, it is noted that thecontroller108 may be implemented as a single device or as two or more separate devices. For example, thecontroller108 may implement the functions of both a motor controller and an engine (or other rotating machine) controller, or thecontroller108 may be implemented separately, as a motor control unit and an engine control unit.

Regardless of the specific physical implementation of thecontroller108, and regardless of the specific control logic that is implemented in thecontroller108, when the shutdown sequence for the rotating machine is initiated, thesystem100 is configured to de-lube the rotating machine. In the depicted embodiment, when the shutdown sequence is initiated, a valve control signal is additionally supplied to thede-lube control valve128 that causes thede-lube control valve128 to move to a position that fluidly communicates thesupply pump inlets117 with the gaseousfluid source126. It will be appreciated that this valve control signal may be supplied from thecontroller108 or from another device. Preferably, however, the valve control signal is supplied from thecontroller108. When the shutdown sequence is initiated, a de-lube signal indicating that the rotating machine is being de-lubricated is additionally supplied to thecontroller108. The de-lube signal may be generated within thecontroller108 or it may be supplied to thecontroller108 from another device.

No matter the specific source of the de-lube signal, thecontroller108, in response to the de-lube signal, controllably energizes themotor106 from thepower bus115. Because thesupply pump inlets117 are in fluid communication with the gaseousfluid source126, air is discharged from the supply pumps118 into thesupply line124. As alluded to above, the control logic implemented by thecontroller108 during the shutdown sequence controls the rotational speed of themotor106 in accordance with a schedule that will displace at least a substantial volume of the lubricant in the rotating machine with air from the gaseousfluid source126.

In addition to the above, thecontroller108 is also responsive to the de-lube signal to cause thebypass control valve146 to move to a position that results in thefluid bypass line144 remaining at least substantially full of lubricant when the lubricant is displaced from thefluid supply line124 and the rotating machine. The manner in which thecontroller108 implements this functionality may vary, but in the depicted embodiment thecontroller108 supplies one or more signals that results in thebypass control valve146 moving to the open position. With thebypass control valve146 in the open position, the air being discharged by the pump will preferentially flow through thefluid supply line124 and into and through the rotating machine, rather than through thefluid bypass line144. This will result in the lubricant being displaced from thefluid supply line124 and the rotating machine, yet thefluid bypass line144 will remain full, or at least substantially full, of lubricant.

As was just noted, thecontroller108 may cause thebypass control valve146 to open in accordance with any one of numerous implementations. In one particular embodiment, thecontroller108 supplies one or more signals that directly or indirectly results in an increased flow rate of the fluid from thesecond fluid system175 through theheat exchanger154. Because the flow rate of this fluid through theheat exchanger154 increases, the amount of heat transfer from the lubricant to the fluid also increases, thereby cooling the lubricant in thefluid bypass line144. The increase in flow rate of the fluid from thesecond fluid system175 through theheat exchanger154 is sufficient to maintain lubricant temperature at the outlet of thebypass control valve146 at or below the temperature at which thebypass control valve146 will open.

It will be appreciated that in other embodiments, such as when thebypass control valve146 is disposed in thefluid bypass line144, thecontroller108 will supply one or more signals that directly or indirectly cause thebypass control valve146 to remain closed. It will additionally be appreciated that for those embodiments in which thebypass control valve146 is implemented with an electric, hydraulic, or pneumatic actuator, the controller could supply suitable signals directly to the actuator that appropriately position thebypass control valve146 to either prevent or inhibit air flow through thefluid bypass line144 during the de-lubrication portion of the machine shutdown sequence.

The above-described process results in a portion of thelubrication supply system100 remaining full, or at least substantially full, of lubricant following the shutdown of the rotating machine. Hence, the lubricant fill volume during a subsequent start sequence of the rotating machine will be reduced relative to a system that is fully purged of its lubricant, and the lubricant pressure in thesystem100 will rise relatively quicker. As a result, the electrical power drawn by themotor106 during the start sequence is significantly reduced relative to a system that was fully purged of its lubricant.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt to a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. An aircraft lubrication supply system, comprising:

a motor coupled to be selectively energized from a power bus and operable, upon being energized, to rotate at a rotational speed and supply a drive force;

a pump having at least a fluid inlet and a fluid outlet, the pump coupled to receive the drive force from the motor and configured, in response thereto, to draw fluid into the fluid inlet from either a lubricant source or a gaseous fluid source, and to discharge the fluid via the fluid outlet;

a fluid supply line coupled to the fluid outlet and configured to supply the fluid discharged from the fluid outlet to a rotating machine;

a fluid bypass line having an inlet and an outlet, the fluid bypass line inlet coupled to the fluid supply line at a first location, the fluid bypass line outlet coupled to the fluid supply line at a second location that is downstream of the first location;

a bypass control valve disposed between the fluid bypass line inlet and the fluid bypass line outlet, the bypass control valve operable to control fluid flow at least through the fluid bypass line; and

a controller configured to couple to the power bus and to receive a machine de-lube signal, the machine de-lube signal indicating that the rotating machine is being de-lubricated, the controller operable, upon receipt of the machine de-lube signal, to:

(i) controllably energize the motor from the power bus to thereby displace at least a substantial volume of lubricant in the fluid supply line and the rotating machine with fluid from the gaseous fluid source, and

(ii) cause the bypass control valve to move to a position that results in the fluid bypass line remaining at least substantially full of lubricant when the at least substantial volume of lubricant is displaced from the fluid supply line and the rotating machine.

2. The system ofclaim 1, wherein the bypass control valve is disposed in the supply line between the first location and the second location.

3. The system ofclaim 1, wherein the bypass control valve is disposed in the fluid bypass line between the bypass inlet and the fluid bypass line outlet.

4. The system ofclaim 1, wherein the bypass control valve is responsive to fluid temperature to thereby control fluid flow at least through the fluid bypass line.

5. The system ofclaim 1, further comprising:

a heat exchanger coupled to receive fluid flowing in the fluid bypass line and a second fluid flowing in a second fluid system at a flow rate, the heat exchanger configured to allow heat transfer between the fluid flowing in the bypass line and the second fluid.

6. The system ofclaim 5, wherein the controller, upon receipt of the machine de-lube signal, causes the flow rate of the second fluid to the heat exchanger to vary.

7. The system ofclaim 6, wherein the controller, upon receipt of the machine de-lube signal, causes the flow rate of the second fluid to the heat exchanger to increase.

8. The system ofclaim 1, further comprising:

a de-lube control valve in fluid communication with the pump fluid inlet, the de-lube control valve movable between at least a first position, in which the pump fluid inlet is in fluid communication with the gaseous fluid source, and a second position, in which the pump fluid inlet is not in fluid communication with the gaseous fluid source.

9. The system ofclaim 8, wherein the de-lube control valve is coupled to receive one or more de-lube valve control signals and is operable, in response thereto, to move to either the first or the second position.

10. The system ofclaim 9, wherein the controller is further operable, in response to the de-lube signal, to supply a valve control signal that causes the de-lube control valve to move to the second position.

11. An aircraft lubrication supply system, comprising:

a bypass control valve disposed in the fluid supply line between the first location and the second location, the bypass control valve responsive to fluid temperature to control fluid flow through the fluid bypass line; and

12. The system ofclaim 11, further comprising:

13. The system ofclaim 12, wherein the controller, upon receipt of the machine de-lube signal, causes the flow rate of the second fluid to the heat exchanger to vary.

14. The system ofclaim 6, wherein the controller, upon receipt of the machine de-lube signal, causes the flow rate of the second fluid to the heat exchanger to increase.

15. The system ofclaim 1, further comprising:

16. A method of removing lubricant from a lubrication supply system and a rotating machine supplied with lubricant by the lubrication supply system, the method comprising the steps of:

supplying a gaseous fluid to the lubrication supply system to displace the lubricant;

preferentially directing the gaseous fluid through a first section of the lubrication supply system and to the rotating machine, and at least inhibiting the gaseous fluid from flowing through a second section of the lubrication supply system,

whereby the gaseous fluid displaces the lubricant in the rotating machine and in the first section of the lubrication supply system, and the second section of the lubrication supply system remains at least substantially full of lubricant.

17. The method ofclaim 16, wherein the lubrication supply system includes a control valve that, based on its position, selectively at least inhibits fluid flow through the second section of the lubrication supply system, and wherein the method further comprises:

positioning the control valve to a position that at least inhibits fluid flow through the second section of the lubrication supply system.

18. The method ofclaim 16, wherein:

the control valve is disposed in the first section of the lubrication supply system; and

the step of position the control valve comprises positioning the control valve to an open position.

19. The method ofclaim 16, wherein

the control valve is disposed in the second section of the lubrication supply system; and

the step of position the control valve comprises positioning the control valve to a closed position.

20. The method ofclaim 16, further comprising:

disposing a heat exchanger in the second section of the lubrication supply system;

flowing fluid in the second section of the lubrication system and a second fluid from a second fluid system through the heat exchanger; and

increasing the flow of the second fluid through the heat exchanger.