Manifold selection metering system

Abstract

A system and method for providing primary reliability of a primary fuel manifold by providing metered fuel from a secondary fuel metering system when a primary fuel metering system fails is provided. The system utilizes a switching electro-hydraulic servo valve (EHSV), an emission selector valve (DSV) coupled to the EHSV, and a pair of throttle valves located between a secondary fuel metering system and primary and secondary fuel manifolds. The DSV has a multi-shoulder piston that switches a control pressure and a shut-off pressure between a pair of throttle valves to switch a supply of metered fuel of a secondary fuel metering system from a secondary fuel manifold to a primary fuel manifold. The output pressurization valve of the failed main fuel metering system is also closed to isolate the failed main fuel metering system from the main fuel manifold.

Description

Technical Field

[0001] The present invention generally relates to multi-stage gas turbine fuel systems, and more specifically, to a manifold switching and selection system for multi-stage gas turbine fuel systems, which provides redundant fuel supply to ensure continued operation of the main combustion chamber in the event of a main fuel control failure. Background Technology

[0002] Typical multi-stage gas turbine fuel systems (such as those described in U.S. Patent No. 7,096,658, entitled "Centrifugal Pump Fuel System and Method for Gas Turbines" by Wernberg et al., assigned to the assignee of this application (hereinafter referred to as the "'658 Patent"), the teachings and disclosure of which are incorporated herein by reference in their entirety) utilize a single fuel metering unit (FMU) to meter fuel flow downstream of the main combustion chamber stage, for example, to power an aircraft as needed. The FMU typically includes a single main reliable fuel metering valve (FMV). This FMV may include a dual-channel linear variable differential transformer (LVDT) to provide feedback on the position of the fuel metering valve. A full authority digital electronic controller (FADEC) uses the position of the FMV to regulate the metered fuel flow. The FADEC positions the FMV by supplying an electrical signal to an electro-hydraulic servo valve (EHSV), which provides hydraulic power to adjust the FMV to the desired position.

[0003] To increase fuel control redundancy in applications such as those described in patent '658, and taking into account the increased criticality of the main combustion chamber stage in this and other applications, the main fuel metering system 101 utilizes redundant EHSVs 103, 105 to control the FMU's FMV 107, such as... Figure 1 As shown. To provide this redundancy, a switching system including switching valve 109 is included to allow FADEC to select which of the two redundant EHSVs 103, 105 to use to control FMV 107. In the event of a failure in control of EHSV 103, FADEC can send a signal to the switching system to switch control to the second EHSV 105 via switching valve 107, thereby maintaining control of FMV 107.

[0004] As described in patent '658, this multi-stage system also includes additional combustion chamber stages, each including a similar fuel control system 111. In an exemplary embodiment described in patent '658, such additional combustion chamber stages may include afterburner regions, each afterburner region utilizing an afterburner or secondary fuel control system 111 to provide metered flow rates to the respective secondary regions. Although Figure 1 Only a single additional secondary fuel control system 111 is shown, but additional secondary combustion chamber stages can utilize additional fuel control systems.

[0005] The secondary fuel metering system 111 includes a single FMV 113 and a dual-channel LVDT to provide feedback on the FMV position. FADEC uses the position of the FMV 113 to regulate the metered fuel flow to the respective secondary zones. Similar to the primary combustion chamber stage fuel control 101, FADEC positions each FMV 113 by supplying an electrical signal to an EHSV 115, which provides hydraulic actuation force to adjust the FMV 113 to the desired position. Unlike the primary combustion chamber stage, which has evolved to include redundant EHSV control, these additional combustion chamber stages are generally equally important, and therefore, it is not worthwhile to increase the cost and weight of such redundant control components.

[0006] Figure 1 The normal operating mode of an existing fuel metering system with redundant EHSV 103 and 105 is shown. Figure 2 The operation is shown in the event of a failure in the control EHSV 103. Figure 1 In the middle, using switching valve 109 (see also) Figure 5 The switching system is configured such that control pressure from main channel A EHSV 103 is supplied via solid lines 117, 119 to position main FMV 107. Control pressure from main channel B EHSV 105, shown by dashed line 121, is blocked at switching valve 109 and cannot flow into main FMV 107. Control of the additional combustion chamber-level metering system EHSV 115 is not associated with the main metering system, even if it is in a parallel fluid loop (or, in some embodiments, a separate fluid loop).

[0007] exist Figure 2 In this configuration, the switching system is positioned such that control pressure from main channel B EHSV 105 is supplied via solid lines 121, 119 to position main FMV 107. Control pressure from main channel A EHSV 103, now shown as dashed line 117, is blocked at switching valve 109 and cannot flow into main FMV 107. This switching of control EHSVs indicates a failure of main channel A EHSV 103. The control of secondary metering system EHSV 115 is not associated with the main metering system and therefore is unaffected by failures or switching of metering control in the main combustion chamber stage.

[0008] As discussed above, in the event of a failure in controlling EHSV 103, redundant EHSVs 103 and 105 are provided to maintain the operation and control of the critical main combustor stage FMV 107, resulting in the use of three EHSVs 103, 105, and 115 to control two combustor stages. Unfortunately, this redundancy in the main combustor stage comes at the cost of increased weight and cost. For the aircraft-based implementation, this added weight incurs additional costs beyond component costs due to increased fuel consumption.

[0009] To address these issues, co-pending application serial number 18 / 340,508 (“508 application”), filed June 23, 2023, entitled “Redundant Electro-hydraulic Servo Valve (EHSV) Control in a Fuel Metering System” and assigned to the assignee of this application (which claims the benefit of U.S. Provisional Patent Application No. 63 / 355,841, filed June 27, 2022, the teachings and disclosures of both applications are incorporated herein by reference in their entirety) provides a fuel control system for a multi-stage combustion chamber that provides a redundant FMV EHSV to ensure the primary reliability of the main combustion chamber metering system without adding undesirable cost, weight, size, and complexity to the engine. Embodiments of the invention described herein provide a system that eliminates dedicated redundant EHSVs and minimizes the hardware associated with connectors, harnesses, and FADEC.

[0010] While offering significant advantages over existing systems when a failure occurs in the control EHSV, in other cases where the failure more broadly affects the main combustion chamber metering system, a more extensive solution may be needed to maintain primary reliability, rather than simply switching control to a redundant FMV EHSV.

[0011] In this context, a manifold selection system can be expected for this redundant fuel metering system, performing selection and isolation of fuel supply between the primary and secondary fuel manifolds to overcome this broader failure. Indeed, in the event of a failure causing a loss of metered flow in the primary engine manifold, what is needed is to supply the secondary metered flow source to the primary engine manifold while simultaneously cutting off the fuel flow supply path previously supplied from that source to the secondary manifold. In this way, the source and control of the secondary manifold metering system can continue to be used to supply metered flow to the primary engine manifold. Fuel control systems such as those described in '658 patent and '508 application require solutions that address this regardless of other redundant control structures involved in the EHSV.

[0012] This switching of metered fuel supply can be accomplished by adding a switching valve 300 controlled by the EHSV 302 to maintain the primary reliability of the main engine manifold, such as... Figure 3 and Figure 4 As shown. Specifically, during normal operation, the switching valve 300, as... Figure 3 The system is positioned such that a metered fuel supply from the main fuel metering system 101 is supplied to the main engine manifold, and a metered fuel supply from the secondary fuel metering system 111 is supplied to the secondary engine manifold.

[0013] In the event of a malfunction in the main fuel metering system 101, the EHSV 302 is commanded to position the switching valve 300, such as... Figure 4 As shown. In this switching position, the metered fuel supply to the main engine manifold is switched from the malfunctioning main fuel metering system 101 to the secondary fuel metering system 111. In this switching position, the metered fuel supply to the secondary manifold is disabled to ensure the primary reliability of the main engine manifold and the control of metered fuel flow.

[0014] Unfortunately, using such Figure 3 and Figure 4 The switching valve 300 shown, controlled by the switching EHSV 302, supplies a secondary metered flow source to the main engine manifold while simultaneously cutting off the fuel flow supply path to the secondary manifold. This requires that the switching valve 300 be sized to handle both the main manifold fuel flow and the secondary manifold fuel flow with relatively low pressure loss during normal operation. Figure 3 In some fuel control systems, the size of such a switching valve to meet these requirements is not permissible. Furthermore, this switching valve 300 needs to ensure complete isolation between the main manifold and the secondary manifold to prevent any metering flow errors or shut-off leakage to the secondary manifold. This additional requirement also increases the weight and size of the switching valve 300.

[0015] In view of the above, embodiments of the present invention provide an improved manifold selection system that does not suffer from the aforementioned problems and other issues present when using switching valves. These and other advantages of the invention, as well as additional inventive features, will become apparent from the description of embodiments of the invention provided herein. Summary of the Invention

[0016] In view of the above, embodiments of the present invention provide systems and methods for ensuring the primary reliability of a main fuel manifold in the event of a failure of the main fuel metering system. In some embodiments, this is accomplished by supplying metered fuel from a secondary fuel metering system. In other embodiments, the manifold selection system and method are capable of switching the output of the fuel metering system to one of a plurality of fuel manifolds.

[0017] In some embodiments of the invention, the system utilizes a switching electro-hydraulic servo valve (EHSV), an exhaust selection valve (DSV) coupled to the EHSV, and a pair of throttle valves located between the secondary fuel metering system and the main fuel manifold. In this embodiment, the DSV has a multi-land piston that switches control and cut-off pressures between the pair of throttle valves to switch the fuel supply metered by the secondary fuel metering system from the secondary fuel manifold to the main fuel manifold. The output pressure valve of a malfunctioning main fuel metering system is also closed to isolate the malfunctioning main fuel metering system from the main fuel manifold.

[0018] In one embodiment of the invention, in the event of a failure causing a loss of metered flow in the main engine manifold, a manifold selection system operates to supply a secondary metered flow source to the main engine manifold. In another embodiment of the invention, a method is provided to disconnect the fuel flow supply path to the secondary manifold and switch the control of the secondary manifold metering system to supply metered flow to the main engine manifold.

[0019] In the normal operating mode of this embodiment of the invention, the fuel flow rate metered in the main engine manifold is supplied by the main metering system. The overspeed and shut-off valve (OSSV) and the emission selector valve (DSV) remain in their normal operating positions, isolating the main manifold and the secondary metering system from each other through a closed standby mode throttle valve.

[0020] In this embodiment, the secondary FMV EHSV controls the position of the secondary metering valve based on commands from the FADEC. The head regulator senses the differential pressure at the main FMV metering port and acts as a variable restriction device in series with the orifice to change the throttle valve control pressure (P5). The secondary throttle valve acts as a variable restriction device in series with the FMV to maintain a nearly constant differential pressure at the FMV port. With a nearly constant differential pressure at the FMV port, the flow rate becomes a function of the FMV position.

[0021] When the FMU is operating in standby mode, especially in the event of a failure in the main pump or main metering system, the DSV to EHSV is switched to standby mode. High-pressure flow from the DSV to the EHSV first slew the OSSV, delivering high-pressure fuel to the downstream side of the main pressurization and shut-off valve, causing it to close rapidly. The high-pressure flow from the OSSV then slew the DSV back to the standby position. With the DSV in standby position, the head regulator control pressure (P5) switches from the secondary throttle valve to the standby mode throttle valve, and supplies high pressure to close the secondary throttle valve. With the standby throttle valve activated, secondary metering flow is allowed to pass through this valve as combustion flow into the main combustion chamber.

[0022] In other embodiments, the OSSV and DSV are combined into a single valve. In a further embodiment, the system utilizes a pressurization valve instead of a throttle valve to bypass the secondary metering system to the main engine manifold. Additional or different secondary (i.e., tertiary, etc.) fuel metering stages can be used to provide primary reliability for the main engine combustion chamber, and / or any metering stage with a higher reliability priority.

[0023] In embodiments of the invention, a manifold selection metering system for supplying metered fuel from a fuel metering system to one of a first fuel manifold or a second fuel manifold includes a switching electro-hydraulic servo valve (EHSV), an exhaust selection valve (DSV) operably coupled to the EHSV, a first throttle valve located between the fuel metering system and the first manifold, and a second throttle valve located between the fuel metering system and the second manifold. The DSV has multiple shoulder pistons configured to switch the throttle valve control pressure from the second throttle valve to the first throttle valve and to switch the throttle valve cut-off pressure from the first throttle valve to the second throttle valve.

[0024] In an embodiment, when the switching EHSV is commanded to enter a first state, metered fuel from the fuel metering system is supplied to the second fuel manifold. The first state positions the multiple shoulder pistons of the DSV to a rest position, such that the throttle valve control pressure is connected to the second throttle valve and the throttle valve cut-off pressure is connected to the first throttle valve. Preferably, in this state, the metered fuel from the fuel metering system is isolated from the first fuel manifold.

[0025] In an embodiment, when the switching EHSV is commanded to enter the second state, metered fuel from the fuel metering system is supplied to the first fuel manifold to return the multiple shoulder pistons of the DSV to the commanded position, such that the throttle control pressure is connected to the first throttle valve and the throttle cut-off pressure is connected to the second throttle valve. Preferably, in this state, the metered fuel from the fuel metering system is isolated from the second fuel manifold.

[0026] In one embodiment, the system further includes an overspeed shut-off valve (OSSV) fluidly coupled to the EHSV. Preferably, the OSPV includes a piston configured to, when commanded by the EHSV, connect a switching pressure to the DSV to drive the multiple shoulder pistons from a rest position to a commanded position, thereby switching the throttle control pressure from the second throttle valve to the first throttle valve, and switching the throttle shut-off pressure from the first throttle valve to the second throttle valve.

[0027] In one embodiment, the system further includes a pressure valve configured to supply metered fuel from a second fuel metering system to the first fuel manifold when the switching EHSV is commanded into the first state. Preferably, when the switching EHSV is in the first state, the metered fuel from the second fuel metering system is isolated from the first fuel manifold, thereby placing the multiple shoulder pistons of the DSV in the commanded position, such that the throttle valve shut-off pressure is connected to the pressure valve. More preferably, this embodiment includes an overspeed shut-off valve (OSSV) fluidly coupled to the EHSV, wherein the OSPV includes a piston configured to, when commanded by the EHSV, connect the switching pressure to the DSV and to the pressure valve, thereby driving the multiple shoulder pistons from a rest position to the commanded position. In one embodiment, a limiting device is provided between the OSPV and the DSV such that the switching pressure first closes the pressure valve before returning the multiple shoulder pistons from the rest position to the commanded position.

[0028] In another embodiment, a manifold selective metering system is provided for switching metered fuel supplied from a secondary fuel metering system from the secondary fuel manifold to the primary fuel manifold in the event of a failure of the primary fuel metering system supplying the primary fuel manifold. The manifold selective metering system includes a switching electro-hydraulic servo valve (EHSV), an overspeed shut-off valve (OSSV) fluidly coupled to the EHSV, an exhaust selective valve (DSV) operably coupled to the OSPV, a pressurization valve configured to supply metered fuel from the primary fuel metering system to the primary fuel manifold, a first throttle valve located between the secondary fuel metering system and the primary fuel manifold, and a second throttle valve located between the secondary fuel metering system and the secondary fuel manifold. The OSPV includes a piston configured to, when commanded by the EHSV, connect a switching pressure to the pressurization valve, thereby isolating the primary fuel metering system from the primary fuel manifold. The piston is also configured to, when commanded by the EHSV, connect the switching pressure to the DSV to drive the multiple shoulder pistons of the DSV from a rest position to a command position, thereby switching the throttle valve control pressure from the second throttle valve to the first throttle valve and switching the throttle valve shut-off pressure from the first throttle valve to the second throttle valve.

[0029] In one embodiment, the system further includes a limiting device between the OSSV and the DSV, such that the switching pressure first closes the pressurization valve before the multiple shoulder pistons are returned from the rest position to the command position.

[0030] In an embodiment, when the switching EHSV is commanded to enter the first state, metered fuel from the secondary fuel metering system is supplied to the secondary fuel manifold, thereby placing the multiple shoulder pistons of the DSV in the rest position, such that the throttle valve control pressure is connected to the second throttle valve and the throttle valve cut-off pressure is connected to the first throttle valve. Preferably, when the switching EHSV is in the first state, the metered fuel from the secondary fuel metering system is isolated from the first fuel manifold.

[0031] In one embodiment, when the switching EHSV is commanded into the second state, metered fuel from the secondary fuel metering system is supplied to the main fuel manifold, thereby placing the multiple shoulder pistons of the DSV in the commanded position, such that the throttle control pressure is connected to the first throttle valve and the throttle shut-off pressure is connected to the second throttle valve. Preferably, when the switching EHSV is in the second state, the metered fuel from the secondary fuel metering system is isolated from the secondary fuel manifold. In another embodiment, the throttle control pressure is provided by the secondary head regulator of the secondary fuel metering system as the pressure differential at the metering port of the fuel metering valve (FMV) of the secondary fuel metering system.

[0032] In embodiments of the present invention, a method is provided to provide primary reliability of a main fuel manifold in the event of a failure of a main fuel metering system to which it supplies metered fuel. The method includes the steps of: isolating the main fuel metering system from the main fuel manifold, isolating a secondary fuel metering system from the secondary fuel manifold, and connecting the secondary fuel metering system to the main fuel manifold.

[0033] In an embodiment, the step of isolating the primary fuel metering system from the primary fuel manifold includes closing the pressurization valve that fluidly connects the primary fuel metering system to the primary fuel manifold. Preferably, the step of isolating the secondary fuel metering system from the secondary fuel manifold includes closing a first throttle valve that fluidly connects the secondary fuel metering system to the secondary fuel manifold. More preferably, the step of connecting the secondary fuel metering system to the primary fuel manifold includes switching the throttle valve cutoff pressure from a second throttle valve that fluidly connects the secondary fuel metering system to the primary fuel manifold to the first throttle valve; and switching the throttle valve control pressure from the first throttle valve to the second throttle valve.

[0034] In an embodiment, the method further includes the step of commanding a switching electro-hydraulic servo valve (EHSV) to rotate the piston of an overspeed shut-off valve (OSSV), the overspeed shut-off valve being fluidly coupled to the EHSV to connect switching pressure to the pressurization valve, thereby closing the pressurization valve to isolate the main fuel metering system from the main fuel manifold, connecting the switching pressure to an emission selector valve (DSV) to drive the multiple shoulder piston of the DSV from a rest position to a command position, thereby switching the throttle valve control pressure from the first throttle valve to the second throttle valve, and switching the throttle valve shut-off pressure from the second throttle valve to the first throttle valve.

[0035] Other aspects, objectives, and advantages of the present invention will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings. Attached Figure Description

[0036] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate several aspects of the invention and, together with the description, serve to explain the principles of the invention. In the drawings:

[0037] Figure 1 This is a simplified block diagram of a prior art fuel metering system for a multi-stage combustion chamber with redundant fuel metering control for the main stage combustion chamber. The diagram illustrates normal, trouble-free operation. Figure 2 This is a simplified block diagram of a prior art fuel metering system for a multi-stage combustion chamber, which has... Figure 1 The redundant fuel metering control of the main stage combustor is illustrated in the figure, showing the redundant fuel metering operation of the main stage combustor during a main FMV control failure. Figure 3 This is a simplified block diagram of a fuel metering and switching system for a multi-stage combustion chamber with redundant fuel metering and switching for the main stage combustion chamber. The diagram illustrates normal, trouble-free operation. Figure 4 This is a simplified block diagram of a fuel metering and switching system for a multi-stage combustion chamber, which has... Figure 3 The diagram illustrates the redundant fuel metering switching of the main stage combustion chamber during a main fuel metering system failure. Figure 5 This is a simplified block diagram and partial schematic diagram of an embodiment of a manifold selective fuel metering system for a multi-stage combustion chamber with redundant fuel metering control for the primary combustion chamber. The diagram illustrates normal, trouble-free operation. Figure 6 This is a simplified block diagram and partial schematic diagram of a manifold selective fuel metering system for a multi-stage combustion chamber, which has the following features: Figure 5 The diagram illustrates the redundant fuel metering control of the main stage combustor during a main fuel metering system failure. Figure 7 This is a simplified schematic diagram illustrating an embodiment of the manifold selection system of the present invention, showing the selection of a first manifold; Figure 8 It is shown in the figure. Figure 7 The figure shown is a simplified schematic diagram of an embodiment of the manifold selection system of the present invention, illustrating the selection of a second manifold; Figure 9 This is a simplified schematic diagram illustrating an embodiment of the manifold selective fuel metering system of the present invention, showing manifold selection during normal fuel metering control; and Figure 10 It is shown in the figure. Figure 9 The figure shown is a simplified schematic diagram of an embodiment of the manifold selective fuel metering system of the present invention, illustrating manifold selection during a failure of the main fuel metering system.

[0038] While the invention will be described in conjunction with certain preferred embodiments, it is not intended to limit it to these embodiments. Rather, the invention is intended to cover all alternatives, modifications, and equivalents included within the spirit and scope of the invention as defined by the appended claims. Detailed Implementation

[0039] Turning back to the attached figures, especially referring to... Figures 5 to 10 The illustration depicts an embodiment of the manifold selective fuel metering system of the present invention. As will be apparent from the foregoing and further discussed below, various embodiments of the manifold selective system and method of the present invention are particularly suitable for multi-stage combustion chambers, such as multi-stage turbine engines used in aircraft. However, as those skilled in the art will recognize from the following description, the application of the manifold selective system described herein in such an operating environment is provided by way of example rather than limitation. In fact, various inventive features of the present invention can find applicability outside the aerospace industry, for example, in industrial multi-stage turbines or multi-stage turbine power generation systems where priority reliability of certain stages or combustion chambers is required.

[0040] Reference Figure 5 The diagram illustrates the manifold selection system 500, which provides an additional degree of major reliability to the main engine manifold supplied by the main fuel metering system 101, as shown above. Figure 1 However, it should be noted that while the main fuel metering system 101 utilizes redundant EHSVs 103 and 105 for control of the main system fuel metering valve (FMV) 107 as described above, redundant main system fuel metering valve control can also be provided according to the description in the '508 application also discussed above. However, because the manifold selection system 500 provides a certain degree of redundancy to maintain the primary reliability of the main combustion zone, a backup EHSV is not required in some applications where this level of additional redundancy in the main combustion chamber is not necessary.

[0041] like Figure 5 As shown in the embodiment, under normal operating conditions, fuel is supplied to the main engine under the normal control of the main fuel metering system 101, regardless of whether the main channel A EHSV 103 or the main channel BEESHV 105 controls the main system fuel metering valve 107. Under the full control of the secondary fuel metering system 111, fuel is also supplied to the secondary combustion zone of the engine. In this mode, the emission selection valve (DSV) 506 is positioned to keep the standby mode throttle valve 508 in the closed position, thereby isolating the main fuel metering system 101 from the secondary fuel metering system 111.

[0042] In the event of a failure of the main fuel pump or other components, causing a failure of the main fuel metering system 101, the manifold selection system 500 operates to supply metered fuel from the secondary fuel metering system 111 to the main engine manifold to maintain the primary reliability required in the main combustion zone.

[0043] like Figure 6 As shown, FADEC (not shown) commands the emission selector valve to switch EHSV 502 into standby mode. High pressure then flows from the DSV to switch EHSV 502, first reversing OSSV 504 to deliver high-pressure fuel to the rear of the main pressurization valve 510, causing it to close rapidly to isolate components of the main fuel metering system 101 from the main engine manifold. The high-pressure flow from OSSV 504 is also connected to DSV 506 to reversing it. Figure 6 The alternative location is shown.

[0044] When the DSV 506 is in the standby position, the head regulator control pressure (P5) switches from the secondary throttle valve 512 to the standby mode throttle valve 508 to control it. Furthermore, with the DSV 506 in the standby position, high pressure is supplied to the secondary fuel metering system throttle valve 512 to close it and isolate the secondary fuel metering system 111 from the secondary engine manifold.

[0045] When the standby mode throttle valve 508 is activated, secondary metering flow from the secondary fuel metering system 111 is allowed to pass through this valve 508 as combustion flow into the main combustion chamber. In other words, the multiple shoulder pistons of the DSV 506 cause control pressure P5 to reverse from the secondary fuel metering system throttle valve 512 to the standby mode throttle valve 508 to control its metering, and conversely apply high pressure from the standby mode throttle valve 508 to the secondary fuel metering system throttle valve 512 to close it and isolate the secondary fuel metering system 111 from the secondary engine manifold. This operation then provides reliable fuel metering to the main engine combustion chamber under the control of the secondary fuel metering system 111.

[0046] Reference Figure 7 This allows for a better understanding of this manifold selective operation. Figure 7 The figure illustrates an embodiment of the manifold selection system 500' in its normal operating mode, wherein a metered fuel supply is provided to a first manifold (the secondary engine manifold in the aforementioned operating environment).

[0047] As shown in the figure, the control of the secondary metering valve 113 is accomplished via the secondary EHSV 115. The head regulator 514 senses the pressure differential at the metering port of FMV 113 and acts as a variable limiting device connected in series with the orifice to change the throttle valve control pressure P5 via DSV 506' to the throttle valve 512. The secondary throttle valve 512 acts as a variable limiting device connected in series with FMV 113 to maintain a nearly constant pressure differential at the FMV 113 port. With the pressure differential at the FMV 113 port nearly constant, the flow rate becomes a function of the FMV 113 position.

[0048] Fuel supply to the second manifold (the main engine manifold in the aforementioned operating environment) is prevented by the closed standby mode throttle valve 508. This standby mode throttle valve 508 is maintained in the closed position by applying high pressure to its control chamber via DSV 506'. The position of DSV 506' is controlled by OSSV 504', which is positioned by the conversion EHSV 502 under the control of FADEC.

[0049] If fuel needs to be supplied to the second manifold (the main engine manifold in the aforementioned operating environment), the command to switch EHSV 502 to switch OSSV 504' to supply high pressure to the control room of DSV 506' is executed, thereby switching its control shoulder to... Figure 8 The position is shown. In this position, DSV 506' now connects control pressure P5 to standby mode throttle valve 508 to provide a controlled, metered flow to the second manifold. In this position, DSV 506' also switches high pressure to the control chamber of throttle valve 512 to force it to close, thereby isolating the first manifold from any further metered fuel flow.

[0050] As is now apparent, based on the selection control signal of the EHSV 502 converter, the flow rate being metered can be switched between different manifolds through the operation of the manifold selection system 500'. This manifold selection system 500' allows for selective control of the flow rate metered to different manifolds as needed.

[0051] Figure 9 Additional details of a manifold selection system 500 are illustrated in the figure. This system is implemented in a system utilizing a primary metering system having a pressure shut-off valve 510 supplying flow to the primary manifold and a secondary throttle valve 512 supplying flow to the secondary manifold. When metered flow needs to be supplied to the primary manifold from a metering system that previously supplied flow to the secondary manifold, the switching EHSV 502 commands the OSSV 504 to switch the high pressure to the pressure shut-off valve 510 and the DSV 506, as previously described.

[0052] Applying high pressure to the pressure shut-off valve 510 will close it, thereby isolating the flow supply of the main manifold from the main metering system. This application of high pressure will also cause DSV 506 to switch, supplying high pressure to the secondary throttle valve 512 to close it, thereby isolating the secondary manifold from the secondary metering system. (As...) Figure 10 As shown, the rotation of DSV 506 also switches the control pressure P5 from the secondary head regulator to the standby mode throttle valve 508 to allow flow to be supplied to the main manifold.

[0053] As can now be seen from the above description, other embodiments of the invention can utilize a single selector valve that combines the operation of OSSV 504 and DSV 506. This single combined valve will simply supply high pressure to the pressure shut-off valve 510 and the secondary throttle valve 512, and switch the secondary head regulator control pressure P5 from the secondary throttle valve 512 to the standby mode throttle valve 508 as its piston rotates.

[0054] Furthermore, those skilled in the art will recognize that other embodiments of the manifold selection system 500 of the present invention may utilize a pressure valve instead of a throttle valve to divert secondary metered flow to the main manifold. In fact, other embodiments of the manifold selection system 500 may utilize an additional secondary metering system from which flow can be applied to different manifolds to maintain a priority system that prioritizes the supply to these different manifolds, or simply maintain different routes for the metered supply flow as needed.

[0055] All references cited in this article, including publications, patent applications and patents, are incorporated herein by reference to the extent that each reference is individually and specifically indicated to be incorporated herein by reference in its entirety and as presented herein.

[0056] In the context of describing the invention (especially in the context of the appended claims), the use of the terms "a" ("a" or "an") and "the," and similar indicative words, is to be construed as covering both the singular and plural, unless otherwise stated herein or obviously contradicted by the context. The terms "comprising" (or "including"), "having," and "comprising" are to be construed as open-ended terms (i.e., meaning "including, but not limited to"), unless otherwise noted. Statements of numerical ranges herein are intended only as shorthand for each individual numerical value falling within the stated range, unless otherwise stated herein, and each individual numerical value is incorporated into this specification as if it were stated separately herein. All methods described herein can be performed in any suitable order, unless otherwise stated herein or obviously contradicted by the context. The use of any and all examples or exemplary language (e.g., "such as") provided herein is merely intended to better illustrate the invention and is not intended to limit the scope of the invention, unless otherwise required. No language in the specification should be construed as indicating any unclaimed element as necessary for the practice of the invention.

[0057] Preferred embodiments of the invention have been described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments will become apparent to those skilled in the art upon reading the foregoing description. The inventors expect those skilled in the art to suitly employ such variations, and the inventors intend to practice the invention in ways other than those specifically described herein. Therefore, as permitted by applicable law, the invention includes all variations and equivalent alternatives to the subject matter listed in the appended claims. Moreover, the invention includes any combination of the foregoing elements in all possible variations, unless otherwise stated herein or clearly contradicted by the context.

Claims

1. A manifold selective metering system for supplying metered fuel from a fuel metering system to one of a first fuel manifold or a second fuel manifold, the manifold selective metering system comprising: Electro-hydraulic servo valve (EHSV); An exhaust selection valve (DSV) operably connected to the EHSV; A first throttle valve located between the fuel metering system and the first manifold; A second throttle valve located between the fuel metering system and the second manifold; and The DSV has multiple shoulder pistons configured to switch the throttle valve control pressure from the second throttle valve to the first throttle valve, and to switch the throttle valve cut-off pressure from the first throttle valve to the second throttle valve.

2. The manifold selection metering system according to claim 1, wherein, When the EHSV is commanded to enter the first state, metered fuel from the fuel metering system is supplied to the second fuel manifold, thereby placing the multiple shoulder pistons of the DSV in a stationary position, such that the throttle control pressure is connected to the second throttle valve and the throttle cut-off pressure is connected to the first throttle valve.

3. The manifold selection metering system according to claim 2, wherein, When the EHSV conversion is in the first state, the fuel metered from the fuel metering system is isolated from the first fuel manifold.

4. The manifold selection metering system according to claim 1, wherein, When the EHSV is commanded to enter the second state, metered fuel from the fuel metering system is supplied to the first fuel manifold, thereby placing the multiple shoulder pistons of the DSV in the commanded position, such that the throttle control pressure is connected to the first throttle valve and the throttle cut-off pressure is connected to the second throttle valve.

5. The manifold selection metering system according to claim 4, wherein, When the EHSV conversion is in the second state, the fuel metered from the fuel metering system is isolated from the second fuel manifold.

6. The manifold selective metering system according to claim 1, further comprising an overspeed shut-off valve (OSSV) fluidly connected to the EHSV, wherein, The OSSV includes a piston configured to, when commanded by the EHSV, connect a switching pressure to the DSV to drive the multiple shoulder pistons from a rest position to a command position, thereby switching the throttle control pressure from the second throttle valve to the first throttle valve, and switching the throttle shut-off pressure from the first throttle valve to the second throttle valve.

7. The manifold selective metering system of claim 2 further includes a pressurization valve configured to supply metered fuel from a second fuel metering system to the first fuel manifold when the switching EHSV is in the first state.

8. The manifold selection metering system according to claim 7, wherein, When the switching EHSV is commanded to enter the second state, the fuel metered from the second fuel metering system is isolated from the first fuel manifold, thereby placing the multiple shoulder pistons of the DSV in the commanded position, causing the throttle valve to cut off the pressure connected to the pressurization valve.

9. The manifold selective metering system of claim 8, further comprising an overspeed shut-off valve (OSSV) fluidly connected to the EHSV, wherein, The OSSV includes a piston configured to, when commanded by the EHSV, connect a switching pressure to the DSV and the pressurization valve, thereby driving the multiple shoulder pistons from a rest position to a commanded position.

10. The manifold selection metering system of claim 8, further comprising a limiting device between the OSSV and the DSV, such that the switching pressure first closes the pressurization valve before the plurality of shoulder pistons are returned from the rest position to the command position.

11. A manifold selective metering system for switching metered fuel supplied from a secondary fuel metering system from the secondary fuel manifold to the primary fuel manifold when a primary fuel metering system malfunctions, the manifold selective metering system comprising: Electro-hydraulic servo valve (EHSV); Fluid connection to the overspeed shut-off valve (OSSV) of the EHSV; An exhaust selection valve (DSV) operably connected to the OSSV; A pressure valve configured to supply metered fuel from the main fuel metering system to the main fuel manifold; A first throttle valve located between the secondary fuel metering system and the main fuel manifold; A second throttle valve located between the secondary fuel metering system and the secondary fuel manifold; and The OSSV includes a piston configured to, when commanded by the EHSV, connect a pressure switching connection to the pressurization valve, thereby isolating the main fuel metering system from the main fuel manifold. The piston is further configured to connect the switching pressure to the DSV when commanded by the EHSV, thereby driving the multiple shoulder pistons of the DSV from a rest position to a command position, thereby switching the throttle valve control pressure from the second throttle valve to the first throttle valve, and switching the throttle valve shut-off pressure from the first throttle valve to the second throttle valve.

12. The manifold selective metering system of claim 11, further comprising a limiting device between the OSSV and the DSV, such that the switching pressure first closes the pressurization valve before the multiple shoulder pistons are rotated from the rest position to the command position.

13. The manifold selection metering system according to claim 11, wherein, When the EHSV is commanded to enter the first state, metered fuel from the secondary fuel metering system is supplied to the secondary fuel manifold, thereby placing the multiple shoulder pistons of the DSV in the stationary position, such that the throttle control pressure is connected to the second throttle valve and the throttle cut-off pressure is connected to the first throttle valve.

14. The manifold selection metering system according to claim 13, wherein, When the EHSV conversion is in the first state, the fuel metered from the secondary fuel metering system is isolated from the first fuel manifold.

15. The manifold selection metering system according to claim 11, wherein, When the switching EHSV is commanded to enter the second state, metered fuel from the secondary fuel metering system is supplied to the main fuel manifold, thereby placing the multiple shoulder pistons of the DSV in the commanded position, such that the throttle control pressure is connected to the first throttle valve and the throttle cut-off pressure is connected to the second throttle valve.

16. The manifold selection metering system according to claim 15, wherein, When the EHSV conversion is in the second state, the fuel metered from the secondary fuel metering system is isolated from the secondary fuel manifold.

17. The manifold selection metering system according to claim 11, wherein, The throttle valve control pressure is provided by the secondary head regulator of the secondary fuel metering system as the pressure difference at the metering port of the fuel metering valve (FMV) of the secondary fuel metering system.

18. A method for providing primary reliability of a main fuel manifold in the event of a failure in a main fuel metering system to which it supplies metered fuel, the method comprising the steps of: Isolate the main fuel metering system from the main fuel manifold; Isolate the secondary fuel metering system from the secondary fuel manifold; Connect the secondary fuel metering system to the main fuel manifold.

19. The method according to claim 18, in, The step of isolating the main fuel metering system from the main fuel manifold includes closing the pressurization valve that fluidly connects the main fuel metering system to the main fuel manifold. The step of isolating the secondary fuel metering system from the secondary fuel manifold includes closing a first throttle valve that fluidly connects the secondary fuel metering system to the secondary fuel manifold, and The step of connecting the secondary fuel metering system to the main fuel manifold includes the following steps: Switching the throttle valve shut-off pressure from the second throttle valve, which fluidly connects the secondary fuel metering system to the main fuel manifold, to the first throttle valve; and Switch the throttle valve control pressure from the first throttle valve to the second throttle valve.

20. The method of claim 19, further comprising the step of commanding a switching electro-hydraulic servo valve (EHSV) to rotate the piston of an overspeed shut-off valve (OSSV), the overspeed shut-off valve being fluidly coupled to the EHSV to connect a switching pressure to the pressurization valve, thereby closing the pressurization valve to isolate the main fuel metering system from the main fuel manifold, and connecting the switching pressure to an emission selector valve (DSV) to drive the multiple shoulder piston of the DSV from a rest position to a command position, thereby switching the throttle valve control pressure from the first throttle valve to the second throttle valve, and switching the throttle valve shut-off pressure from the second throttle valve to the first throttle valve.

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