Patent Publication Number: US-11649768-B2

Title: Pump system for a gas turbine engine

Description:
BACKGROUND 
     Technological Field 
     The present disclosure relates generally to an improved fuel pumping system for a gas turbine engine, and more particularly to a pump system having dual parallel pumps. 
     Description of Related Art 
     Gas turbine engines typically include a compressor compressing air and delivering it to a combustion chamber. The compressed air is mixed with fuel in the combustion chamber, combusted, and the products of combustion pass downstream over turbine rotors, driving the rotors to create power. 
     There are many distinct features involved in a gas turbine engine. As one example only, the compressor may be provided with variable vanes which are actuated to change an angle of incident dependent on system conditions. Actuators for changing the angle of incident of the vanes, and any other actuator or flow demand needed for engine operation, are provided with hydraulic fluid from a positive displacement pump. While conventional engines, components, and methods of designing aircraft engines have generally been considered satisfactory for their intended purpose there is still a need in the art for improved engine architecture that is more efficient and adaptable to extreme and typical conditions. The present disclosure provides a solution for this need. 
     SUMMARY OF THE INVENTION 
     A pump supply system that can employ fuel for a gas turbine engine is disclosed. The system includes a first positive displacement pump connected to a fuel flow demand line delivering fuel to an actuation or burner system based on a fuel flow demand, a second positive displacement pump connected to the fuel flow demand line in parallel to the first pump supplementing fuel to the actuation or burner system based on the fuel flow demand, a pressure regulating valve (PRV) fluidly connected with the first pump and the flow demand line for returning excess flow to a bypass flow fuel line and controlling modulated pressure to a bypass valve, which is in fluid communication with the second pump and the PRV for receiving modulated pressure from the PRV and regulating delivery of fuel from the second pump to a bypass flow fuel line. The system can include an aircraft burner or actuation system. The bypass valve can be hydraulically controlled. The first pump and the second pump can be different sizes. 
     The PRV can be actuated by a first Electro-Mechanical Interface Device (EMID) which receives electronic signals from an Electronic Engine Control (EEC) which measures pressure at the fuel flow line for delivering fuel to the actuation or burner system from the first pump and from the second pump versus the required pressure for the actuation or burner system as determined by the EEC. A pressure sensor can be connected to the fuel flow demand line, configured to measure demand flow pressure to the EEC. A second, independent EMID can be used for controlling the bypass valve. A second independent pressure sensor can be connected to a fuel line connecting the bypass valve and the second pump, configured to supply that pressure data to the EEC. 
     The system can include a first check valve and a second check valve for allowing flow from each of the pumps to the flow demand, wherein fuel flow from the first pump and the second pump to the actuation or burner system is controlled by a corresponding check valve. The PRV can receive bypass fuel flow from the first pump and provides bypass fuel flow directed to the first pump and the second pump inlet. The PRV provides bypass fuel flow directed to the inlet of the first pump and the second pump when the PRV is in at least a partially open position. The PRV is fluidically connected to pump inlet pressure and provides a pressure signal to the bypass valve, with a high pressure signal being provided when the PRV is in a closed position and the signal pressure reducing to pump inlet pressure as the PRV becomes more open. 
     The second check valve can be fully closed during a first mode. The first check valve can be fully open during a first mode. The second check valve can be fully open during a second mode. 
     The bypass valve can be closed during a second mode (to be described as high fuel demand conditions in the specification), allowing the second pump to supplement fuel delivery to the actuation or burner system along the fuel flow demand line. The first check valve can be closed when the first pump is offline. 
     The PRV can be connected to the flow demand line by an orifice line. The orifice line can include an orifice therein for supplying a high pressure flow from the flow demand to modulated pressure which is connected to a signal window within the PRV, which provides flow to the pump inlet, thus reducing the modulated pressure the more open then PRV becomes. 
     These and other features of the systems and methods of the subject disclosure will become more readily apparent to those skilled in the art from the following detailed description of the preferred embodiments taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that those skilled in the art to which the subject disclosure appertains will readily understand how to make and use the devices and methods of the subject disclosure without undue experimentation, embodiments thereof will be described in detail herein below with reference to certain figures, wherein: 
         FIG.  1    is a schematic view of an embodiment of fuel supply system according to the disclosure in a first condition; 
         FIG.  2    is a schematic view of the embodiment of fuel supply system of  FIG.  1   , showing two pumps providing fuel flow; 
         FIG.  3    is a schematic view of the embodiment of fuel supply system of  FIG.  1   , showing a situation when a first pump is not accessible; and 
         FIG.  4    is a schematic view of another embodiment of fuel supply system according to the disclosure in a first condition. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an exemplary embodiment of a fuel system in accordance with the disclosure is shown in  FIG.  1    and is designated generally by reference character  100 . Other embodiments of the system in accordance with the disclosure, or aspects thereof, are provided in  FIGS.  2 - 4   , as will be described. The system can be used with an improved engine architecture that is more efficient and adaptable between extreme and typical flight conditions and flow requirements. 
     Referring now to  FIG.  1   , a fluid supply system  100  for a gas turbine engine is shown. The system  100  includes a first pump  102  connected to a flow demand line  122  delivering fuel to an actuation or burner system  120  based on a fuel flow demand and a second pump  104  connected to the fuel flow demand line  122  in parallel to the first pump  102  for supplementing the first pump  102 . A pressure regulating valve  112  (PRV) is connected to the first pump  102 . The PRV  112  is responsible for ensuring that a proper amount of fuel is distributed from the first and second pump  102 / 104  to the actuation or burner system  120  and a bypass flow  131  that leads back to the inlet of the pumps  102 / 104 . The PRV  112  is also responsible for controlling modulated pressure  128  to the bypass valve  118 . The bypass valve  118  is responsible for modulating the pressure of the second pump  104 . The system  100  can be used on an aircraft as part of a combustion or actuation system. The first pump  102  and the second pump  104  can be different sizes i.e. having different flow rate capabilities, different pressure capability, physical sizes, etc. allowing the system to be optimized for typical conditions and not be sized for the extreme flow conditions. 
     Referring further to  FIG.  1   , the PRV  112  is controlled by a first EMID  110 , from which it receives pressure command signals based on flow demand  120 . The EMID  110  receives signals from the Electronic Engine Control  108 , which is responsible for controlling a plurality of systems. The EEC  108  receives pressure readings from the pressure sensor  136  which measures pressure of the fuel flow demand line  122  and compares it against required pressures. The PRV  112  bypasses flow in order to regulate the pressure of the demand flow. The desired pressure can be changed by adjusting the pressure in the spring cavity of the PRV. The pressure sensor provides pressure signal data to the EEC  108  and depending on the pressure requested by the EEC  108 , an electronic signal is sent to the EMID  110  so that the EMID  110  will increase or decrease the pressure signal to the spring cavity of the PRV  112 , moving the PRV  112  to a more closed or opened position, respectively, thus increasing or decreasing the pressure of the demand flow as requested. It is also considered that a second, independent EMID  409  can be used for controlling the bypass valve  418  (as shown in  FIG.  4   ). In this configuration second independent pressure sensor  437  is also connected to the fuel line connecting the bypass valve  418  and the second pump  404  to supply pressure data to the EEC  408 . 
     Referring again to  FIGS.  1 - 3   , the system  100  includes a first check valve  114  and a second check valve  116 , wherein fuel flow from the first pump  102  and the second pump  104  to the actuation or burner system  120  is controlled by a corresponding check valve  114 / 116 . The PRV  112  can receive fuel flow from the first pump  102  and provide bypass fuel flow  131  directed to the inlet of the first and the second pump  102 / 104 . The first mode is where flow demand is low, for instance when actuators are not moving so flow to the actuators is only enough to satisfy internal leakages in the actuation systems. In this mode, the first check valve  114  is open and the second check valve  116  is closed sending flow from the second pump  104  to the bypass valve  118 . Flow from the bypass valve  118  is fed along line  134  to the bypass line  131  to be fed back to the first and second pump  102 / 104  inlet. The bypass valve  118  is also forced open by flow from the PRV  112  along line  128 . 
     Referring now to  FIG.  2   , a second mode of the system is shown. The second mode includes high fuel demand when actuator(s) are commanded to move, requiring flow from the pump to move them. During high flow demand the second check valve  116  can be partially or fully open. Fuel from the second pump  104  supplements fuel flow from the first pump  102  along fuel demand line  122 . As the fuel demand is high, the PRV  112  closes and limits or stops flow from going to the pump inlet along line  131 . The PRV also closes a signal window  124  partially or completely, which causes the pressure signal to the bypass valve  118  to increase because of the high pressure fed to the modulated pressure line  128  by the orifice  132 . Orifice  132  can be used for supplying a high pressure flow from the flow demand  120  to the modulated pressure line  128  which is connected to signal window  124  in the PRV, which provides flow to the pump inlet, thus increasing the modulated pressure as the PRV closes. The increased signal pressure  128  forces the bypass valve  118  to close partially or completely, which restricts or stops flow from the second pump  104  to the bypass line  134 . There is also an intermediate condition where the second check valve  116  is at least partially open and bypass valve  118  is partially open. As the signal pressure to the bypass valve  118  increases, the bypass valve  118  will close more until it is fully closed. 
     Referring now to  FIG.  3   , when the first pump  102  is offline, such as due to a failure, the first check valve  114  closes. To maintain the required fuel pressure, the PRV  112  closes and does not allow fuel flow to the pump inlet along line  131 . The lack of flow through the signal window  124  in the PRV  112  increases the modulated pressure  128 , which forces the bypass valve  118  to close and not allow flow from the second pump  104  to the bypass line  134  ensuring that flow is supported by the second pump  104 . 
     Referring now to  FIG.  4   , the PRV  412  is controlled by a first EMID  410 , from which it receives pressure command signals based on flow demand  420 . A second, independent EMID  409  is be used for controlling the bypass valve  418 . A second independent pressure sensor  437  is connected to the fuel line connecting the bypass valve  418  and the second pump  404  to supply pressure data to the EEC  408 . 
     In  FIG.  4   , the system is also shown in a first or low demand mode. The first check valve  414  is open and the second check valve  416  is closed sending flow from the second pump  404  to the bypass valve  418 . Flow from the bypass valve  418  is fed along line  434  to the bypass line  431  to be fed back to the first and second pump  402 / 404  inlet. 
     In a traditional pumping system with one pump, the entire flow generated by the pump is at the set pressure and becomes overdesigned for situations where flow is low. In this instance, when the flow demand is low, one of the pumps is operating at a low pressure differential, thus reducing the power needed for pumping and reducing the amount of heat added to the fuel. However, when flow demand increases, both pumps can provide flow in parallel. Also, if one of the pumps fails, the other pump can provide sufficient flow to safely land the aircraft. This feature can, for example, improve safety and reliability. 
     The methods and systems of the present disclosure, as described above and shown in the drawings, are used with an improved engine architecture that is more efficient and adaptable between extreme and typical flight conditions and flow requirements. While the systems and methods of the subject disclosure have been shown and described with reference to preferred embodiments, those skilled in the art will readily appreciate that changes and/or modifications may be made thereto without departing from the scope of the subject disclosure.