Title of Invention

TWO-DISPLACEMENT SETTING VARIABLE DISPLACEMENT PUMP USED AS ENGINE OVER-THRUST PROTECTION WITH FUEL SYSTEM THERMAL BENEFIT

Abstract A fuel delivery system (10) comprises a variable displacement pump (20) for pressurizing fuel. The variable displacement pump has a distinct first pump displacement setting for a first desired mass flow of fuel and a distinct second pump displacement setting for a second desired mass flow of fuel. The variable displacement pump operates in only one of the first and second pump displacement settings. A fuel control (22) with a metering valve downstream of the variable displacement pump selectively regulates fuel delivery.
Full Text

TWO-DISPLACEMENT SETTING VARIABLE
DISPLACEMENT PUMP USED AS ENGINE OVER-THRUST
PROTECTION WITH FUEL SYSTEM THERMAL BENEFIT
Cross Reference to Related Applications
[0001] This application claims priority from U.S. Provisional Patent Application Serial
No. 60/557,429 filed March 29, 2004 and is incorporated herein by reference.
Background of the Invention
[0002] The present invention relates to a fuel delivery system. It finds particular
application in conjunction with modern jet aircraft turbine engines, finding particular
application during a control system failure, and will be described with particular
reference thereto. However, it is to be appreciated that the present exemplary
embodiment is also amenable to other applications.
[0003] Known fuel delivery systems have proven effective to date to provide desired
fuel flow in a wide array of circumstances. Modern jet aircraft engines are now
required to prevent even rare occurrences of uncontrolled engine over-thrust during
control system failures. Cases of gross over-thrusting engines have resulted in
several instances of loss of aircraft control due to substantial asymmetric thrust. As
such, the Federal Aviation Administration (FAA) is considering new airworthiness
regulations that dictate control system design that will prevent engine over-thrust
conditions.
[0004] Engine over-thrust conditions are generally caused by a major foss of control
functions that result in full fuel pump flow being delivered to an engine combustor.
Many schemes are being considered that will bypass the pump delivered flow away
from the engine combustor as to control flow delivered to the combustor, and thus
engine thrust. These systems require additional hardware features that are
independent of the normal control means.
[0005] In addition, as jet aircraft engines become more fuel efficient, modern
engines have an ever increasingly difficult task of managing fuel system heat.
Reduced windmill speeds add to the heat iranagement task by forcing the engine

fuel pump to be of a larger capacity, and therefore generate a larger quantity of heat to be dissipated.
[0006] Accordingly, there is a need for an improved fuel delivery system which provides over-thrust protection with improved fuel system thermal benefit.
Brief Description of the Invention
[0007] A new and improved fuel delivery system for a jet aircraft turbine engine is provided.
[0008] According to one aspect of the invention, the fuel delivery system comprises a system that has only two distinct pump displacement settings. The fuel delivery system preferably employs a variable displacement pump for pressurizing fuel. The variable displacement pump has a distinct first pump displacement setting for a first desired mass flow of fuel and a distinct second pump displacement setting fora second desired mass flow of fuel. The variable displacement pump operates in only one of the first and second pump displacement settings. A metering valve downstream of the variable displacement pump selectively regulates fuel delivery. [0009] In the first position, the variable displacement pump is positioned to deliver a first predetermined, high mass flow, fuel displacement setting as would be required for a large amount of flow such as starting and takeoff. The pump is operative in a second predetermined, low mass flow, fuel displacement setting where reduced flow requirements are needed such as high altitude cruising or descent. A metering valve downstream of the variable displacement pump selectively regulates fuel delivery. A controller selectively positions the pump in only one of the first and second fuel displacement settings. Positioning the pump to operate in the second fuel displacement setting in the event of failure of the controller prevents engine over-thrust. The two-displacement pumping scheme provides a means of preventing engine over-thrust where in the event of major control system failure, the pump is positioned in the second of low flow displacement setting so that the pump will not produce an,amount of flow that will enable the engine to accelerate to full power.
[0010] According to yet another aspect of the invention, a method of delivering fuel for an associated jet aircraft turbine engine is provided. Fuel is pressurized with a variable displacement pump. The pump has first and second fixed displacement

settings for first and second predetermined mass flows of fuel and is set to only one of
the first and second displacement settings. The fuel is metered through a metering
valve for supply to fuel nozzles of the engine.
[0011] A benefit of the present invention is the ability to prevent engine over-thrust
through the use of a variable displacement pump.
[0012] Another benefit of the present invention is the ability to minimize pump
heating during a low flow displacement setting since the pump will contribute less heat
to the fuel system, and permit fuel system heating to avoid fuel system icing at cold
operating conditions by commanding the pump to its high flow displacement setting
under substantially all conditions, regardless of system flow needs.
[0013] Still other benefits and aspects of the invention will become apparent from a
reading and understanding of the detailed description of the preferred embodiments
hereinbelow.
Brief Description of the Drawings
[0014] The present invention may take physical form in certain parts and
arrangements of parts, preferred embodiments of which will be described in detail in this
specification and illustrated in the accompanying drawings which form a part of the
invention.
[0015] FIGURE 1 is a simplified schematic of the fuel delivery system according to
one embodiment of the present invention.
[0016] FIGURE 2 is across-sectional view of a preferred variable flow pump in a first
displacement setting used in the fuel delivery system of FIGURE 1.
[0017] FIGURE 3 is a cross-sectional view of the variable flow pump in a second
displacement setting.
[0018] FIGURE 4 is a graphical representation of speed versus fuel flow of the
variable displacement pump operative in either the first or second displacement
settings.
Detailed Description of the Invention
[0019] It should, of course, be understood that the description and drawings herein
are merely illustrative and that various modifications and changes can be made in the

structures disclosed without departing from the spirit of the invention. Like numerals refer to like parts throughout the several views.
[0020] As schematically illustrated in FIGURE 1, a fuel delivery system 10 of the present invention includes a high pressure variable displacement pump 20, a fuel control 22, a controller 24 and an engine such as a jet aircraft turbine engine 28. Generally, fuel is inlet to a centrifugal boost stage (not shown), initially pressurized and passed through a fuel/oil heat exchanger (not shown) and a filter (not shown) before being input to the pump 20. As shown in FIGURES 2 and 3, and also described in greater detail in co-pending US patent application Serial-No. 10/474,225 (publication 20040136853), filed October 3, 2003 based on PCT/US02/09298, filed March 27, 2002, the preferred, variable displacement pump 20 includes a rotor 40, which has multiple vanes 42 extending therefrom. A cam ring 44 surrounding the rotor and vanes is free to rotate relative to the vanes 42. Thus, substantial losses between the outer tips of the vanes and a stationary cam ring as used in a typical vane pump are not encountered with the present invention. The cam ring 44 is supported in a continuous fluid bearing 46 defined by the pumped fuel. A spacer ring 50 is received around the rotor 40. The spacer ring has a flat or planar cam rolling surface 52 and receives a pin 54. The pin cooperates with a cam sleeve 56 that is received around the rotor 40 to reposition the rotor and vanes to desired pumping positions.
[0021] First and second lobes or actuating surfaces 58, 60 are provided on the sleeve 56, typically at a location opposite the pin. The lobes cooperate with first and second actuator assemblies 64, 66 to define means for altering a position of the cam sleeve 56. The altering means selectively alter the stroke or displacement of the pump in a manner well known in the art. This variable displacement pump is preferred, although it will be understood that still other pumps may be used without departing from the scope and intent of the present invention.
[0022] In accordance with the present invention, the variable displacement pump 20 has a distinct, predetermined first pump displacement setting for a first desired mass flow of fuel (FIGURE 2) and a distinct, predetermined second pump displacement setting for a second desired mass flow of fuel (FIGURE 3). In use, the pump 20 operates in only one of the first and second pump displacement settings, the first pump

displacement setting being a high mass flow displacement setting and the second pump displacement setting being a low mass flow displacement setting. [0023] With reference to FIGURE 2, the actuating assemblies 64, 66 are actuated so that the cam sleeve 56 is positioned to vary the stroke of the pump 20. That is, the cam sleeve 56 is positioned so that a close clearance is defined between the cam sleeve and the spacer ring 50 along the left-hand quadrants of the pump as illustrated in FIGURE 2. In this position, the pump 20 is fixed in its first displacement setting, the high mass flow displacement setting. This flow setting is selected while operational (i.e., does not have to be set while inoperative) so that sufficient fuel flow is provided to the system where large flows are required during operation such as starting and takeoff. [0024] With reference to FIGURE 3, the positions of the actuating assemblies 64, 66 are altered when compared to.FIGURE 2. The cam sleeve 56 is moved to vary the stroke of the vane pump to a second displacement setting,, or the low mass flow displacement setting. This position is used during low flow conditions such as high altitude cruising or descent where flow requirements are reduced. [0025] Thus, as shown in FIGURES 2 and 3, the pump 20 includes a distinct first stop and a distinct second stop, the first and second stops defining first and second positions of pump stroke travel. The first and second positions of pump stroke travel, in turn, define the respective first and second displacement settings (i.e. the operational parameters for pump stroke.travel). These are the only two steady, commanded operational positions of the pump in accordance with the present invention. The pump either operates in a first or low flow condition or in a second or high flow position. It is recognized that the pump will transition through intermediate positions between the first and second displacement settings, however, the actuators and the pump control are operative so that the pump is commanded or directed to operate in these one of the two distinct positions only. That is, if the pump is at the first displacement position and commanded to. the second displacement position, the pump proceeds to the second position without stopping and operating steadily at any intermediate position. [0026] The pump 20 delivers a controllable amount of fuel flow in response to control signals. As shown in FIGURE 1, the output flow from the pump travels in a flow path through the fuel control 22 that includes a metering valve (not shown) where the fuel is directed to the turbine engine 28 and combusted to produce power. The fuel control 22

is downstream of the pump 20 for selectively regulating fuel delivery to the engine. A bypass 80 is provided at the fuel control 22 for returning bypass flow to the pump inlet. Bypass flow is the remaining portion of the variable displacement pump 20 output flow that is not used for combustion purposes. The bypass flow is generally returned through a bypass valve (not shown) to the inlet of the pump 20 after passing through another fuel/oil heat exchanger (not shown). In this system, metered flow is established by adjusting the position of the metering valve of the fuel control 22 to obtain the desired mass flow. The metering valve position of the fuel control 22 is set by the controller 24.
[0027] As noted above, prior art fuel control systems have been inadequate in controlling engine speed in the event of a control system failure. For example, incorporating a hydro-mechanical overspeed governor function to limit engine speed has been used as one solution in the event of a control system failure that would otherwise cause the engine to be uncontrollable. However, typical incorporation of the overspeed governor uses features of the fuel control which are responsible for normal flow regulation and may in fact be the cause for such an uncontrollable event. The present system of FIGURE 1 uses the variable displacement pump 20 to reduce the maximum flow and thereby limit delivered metered fuel flow to the engine 28 and thus prevent the occurrence of a gross over-thrust situation.
[0028] With continued reference to FIGURE 1, the controller 24 positions the pump 20 in one of the first pump displacement setting (FIGURE2) and the second pump displacement setting (FIGURE 3). The controller 24 can be a solenoid valve, for example, -which is responsive to an electronic control signal for actuating the pump 20 to only one of the first and second pump displacement settings. Thus, the solenoid valve is commanded by the controller 24 and positions the pump 20 to one of its first and second modes of operation. In the event of a control system failure that would otherwise cause the engine 28 to over-thrust, the controller 24 positions the pump 20 to operate in the second fuel displacement setting whereby pump flow to the engine is limited.
[0029] In operation, fuel is pressurized through the pump 20 that has first and second fixed displacement settings for first and second predetermined mass flows of fuel. The fuel is metered through a fuel control 22 having a metering valve for supply to

fuel nozzles of the engine 28. The pump 20 is set to only one of the first and second displacement settings (FIGURES 2 and 3).
[0030] With the above operation, fuel system temperature is advantageously controlled by operating the variable displacement pump 20 in either its fixed high mass flow displacement setting (and avoiding fuel system icing in cold operating conditions) or fixed low mass flow displacement setting (and thereby reducing excess heat). Fuel exiting the fuel control 22 is bypassed to recirculate a portion of fuel to the pump 20. [0031 ] In summary, the present system uses the variable displacement pump 20 with physical stops of pump stroke travel, thereby setting two distinct pump displacement settings. Under normal conditions requiring a large amount of pumped flow (such as starting and takeoff), the pump 20 is stroked to the high flow displacement setting (FIGURE 2) to provide the complete range of required engine operation. As flow requirements reduce (at conditions such as high altitude cruise or descent), the pump 20 is placed to its low flow displacement setting (FIGURE 1). With the low flow displacement setting, the pump 20 contributes less heat to the fuel system. A control means such as a solenoid valve commanded by the controller 24 positions the pump 20 to each displacement setting.
[0032] In addition to minimizing pump heating, the proposed system configuration permits fuel system heating to avoid fuel system icing at cold operating conditions. Fuel system heating is accomplished by commanding the pump 20 to its high flow displacement setting under all conditions, regardless of system flow needs. [0033] In addition to providing benefit to the thermal management aspect of the engine, the two-displacement pumping scheme of the pump 20 provides a means of preventing engine over-thrust. In the event of major control system failure that results in full pump flow being delivered to the engine 28, the pump 20 would be set to the low flow displacement setting. At this low flow setting, the pump 20 will not produce an amount of flow that will enable the engine 28 to accelerate to full power. Engine speed (and thus thrust level) will equilibrate at a level depending on the displacement chosen for the low flow setting. In this way, engine over-thrust protection is provided without adding control hardware to the fuel deli\ ery system.
[0034] It will be appreciated that other types of pumps may.be used, namely any type of pump that could be set up into two displacement modes, it could even be a two

stage gear pump, one of which bypasses flow directly and the other stage doing the pumping. However, the illustrated and described variable pump is preferred. [0035] Moreover, although other solutions have been considered, these alternative solutions add additional components to the system, thereby adding to the cost, complexity, and/or the potential that other components could fail. [0036] In one example as shown in FIGURE 4, the first position is 100% flow capacity while the second position is approximately 33% of the pump flow capacity. However, these values are illustrative only and are not to be construed as requirements to achieve the benefits and advantages described above.
[0037] The present invention has been described with reference to. the preferred embodiment. Obviously, modifications and alterations will occur to others upon reading and. understanding the preceding detailed description. It is intended that the exemplary embodiment be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

AMENDED CLAIMS
[received by the International Bureau 10 Jan 2006 (10.01.06);
original claims 1, 5, 9 and 15 amended; claim 6 cancelled and rest
claims remain unchanged (pages 4)]
1. (Amended) A fuel delivery system for an associated jet aircraft turbine
engine during a control system failure comprising:
a pump for pressurizing fuel, the pump having a distinct first pump displacement setting for a first desired mass flow of fuel and a distinct second pump displacement setting for a second, desired mass flow of fuel, wherein the pump operates in only one of the first and second pump displacement settings;
a metering valve downstream of the pump for selectively regulating fuel delivery; and,
means for preventing engine over-thrust operatively associated with the pump for positioning the pump in the second pump displacement setting in response to a control system failure whereby pump flow to the associated engine is limited to provide over-thrust protection.
2. The fuel delivery system of claim 1 wherein the first pump
displacement setting is a high mass flow displacement setting.
3. The fuel delivery system of claim 1 wherein the second pump
displacement setting is a low mass flow displacement setting,
4. The fuel delivery system of claim 3 wherein the pump is activated to
the second pump displacement setting in response to a control system failure.
5. A fuel delivery system for an associated jet aircraft turbine engine
during a control system failure comprising:
a pump for pressurizing fuel, the pump having a distinct first pump displacement setting for a first desired high mass flow of fuel and a distinct second pump displacement setting for a second desired iow mass flow of fuel, wherein the pump operates in only one of the first and second pump displacement settings, wherein the pump is activated to the second pump displacement setting in response to a control system failure;
AMENDED SHEET (ARTICLE 19)

a metering vaive downstream of the pump for selectively regulating fuel delivery; and,
a controller for preventing engine over-thrust operatively associated with the pump for positioning the pump in the second pump displacement setting in response to a control system failure whereby pump flow to the associated engine is limited to provide over-thrust protection.
6. The fuel delivery system of claim 1 wherein the pump includes distinct
first and second stops defining operational parameters for pump stroke travel.
7. The fuel delivery system of claim 1 further comprising a controller for
positioning the pump in one of the first and second pump displacement settings.
8. (Amended) The fuel delivery system of claim 5 or 7 wherein the
controller is a solenoid valve responsive to an electronic control signal for actuating
the pump to only one of the first and second pump displacement settings.
9. The fuel delivery system of claim 1 further comprising a bypass
passage downstream of the pump for returning excess flow to a pump inlet.
10. The fuel delivery system of claim 1 further comprising a solenoid valve,
the solenoid valve being commanded,, by the electronic control for positioning the
pump to one of the first and second modes of operation.
11. The fuel delivery system of claim 1 wherein the second pump
displacement setting contributes less heat to the fuel system.
12. The fuel deliver/ system of claim 1 wherein the first pump
displacement setting permits fuel system heating for avoiding fuel system icing at
cold operating conditions.
13. The fuel delivery system of claim 1 wherein the pump is a variable
displacement pump.
AMENDED SHEET (ARTICLE 19)

14. (Amended) A method of delivering fuel for an associated jet aircraft
turbine engine comprising the stefrs of:
pressurizing fuel through a pump having first and second fixed displacement settings for a first predetermined, high mass flow of fuel and a second predetermined, low mass flows of fuel;
metering the fuel through a metering valve for supply to associated fuel nozzles; setting the pump to only one of the first and second displacement settings; and,
positioning the pump in the second pump displacement setting in response to a control system failure whereby pump flow to the associated engine is limited to provide over-thrust protection.
15. The method of claim 14 comprising the further step of controlling fuel
system temperature by operating the pump in its fixed high mass flow displacement
setting.
16. The method of claim 14 comprising the further step of bypassing fuel
exiting the metering vatve to recirculate a portion of fuel to the pump.
17. A fuel delivery system for preventing engine over-thrust for an
associated jet aircraft turbine engine comprising:
a variable displacement pump for pressurizing fuel operative in either a first predetermined, high mass flow, fuel displacement setting or a second predetermined, low mass flow, fuel displacement setting;
a metering valve downstream of the variable displacement pump for selectively regulating fuel delivery; and,
a controller for selectively positioning the pump in only one of the first and second fuel displacement settings, and positioning the pump to operate in the second fuei displacement setting in the event of failure of the controller thereby preventing engine over-thrust.
AMENDED SHEET (ARTICLE 19)

18. The fuel delivery system of claim 17 wherein the pump includes first
and second stops in first and second extremes of pump stroke travel.
19. The fuel delivery system of claim 18 wherein the first and second
extremes of pump stroke travel define the respective first and second displacement
setting.
Dated this 27 day of September 2006
AMENDED SHEET (ARTICLE 19)

Documents:

3569-CHENP-2006 AMENDED PAGES OF SPECIFICATION 26-06-2013.pdf

3569-CHENP-2006 AMENDED CLAIMS 26-06-2013.pdf

3569-CHENP-2006 CORRESPONDENCE OTHERS 06-08-2012.pdf

3569-chenp-2006 form-6 31-05-2011.pdf

3569-chenp-2006 other document 31-05-2011.pdf

3569-chenp-2006 power of attorney 31-05-2011.pdf

3569-chenp-2006 correpondence others 31-05-2011.pdf

3569-CHENP-2006 EXAMINATION REPORT REPLY RECEIVED 26-06-2013.pdf

3569-CHENP-2006 FORM-1 26-06-2013.pdf

3569-CHENP-2006 FORM-18.pdf

3569-CHENP-2006 FORM-3 26-06-2013.pdf

3569-CHENP-2006 OTHER PATENT DOCUMENT 26-06-2013.pdf

3569-chenp-2006-abstract.pdf

3569-chenp-2006-claims.pdf

3569-chenp-2006-correspondnece-others.pdf

3569-chenp-2006-description(complete).pdf

3569-chenp-2006-drawings.pdf

3569-chenp-2006-form 1.pdf

3569-chenp-2006-form 26.pdf

3569-chenp-2006-form 3.pdf

3569-chenp-2006-form 5.pdf

3569-chenp-2006-pct.pdf


Patent Number 256742
Indian Patent Application Number 3569/CHENP/2006
PG Journal Number 30/2013
Publication Date 26-Jul-2013
Grant Date 23-Jul-2013
Date of Filing 27-Sep-2006
Name of Patentee EATON INDUSTRIAL CORPORATION
Applicant Address 1111 SUPERIOR AVENUE, CLEVELAND OH 44114
Inventors:
# Inventor's Name Inventor's Address
1 CLEMENTS MARTIN A 6581 DEVONSHIRE DRIVE NORTH ROYALTON OH 44133
PCT International Classification Number F02C 9/28
PCT International Application Number PCT/US05/10364
PCT International Filing date 2005-03-29
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 60/557,429 2004-03-29 U.S.A.